Patients in this subset of tricuspid atresia are usually cyanotic from birth because of limited Q ˙ p from right ventricular outflow obstruction. Dick and colleagues reported that in 50% of patients, congenital heart disease is recognized on the first day of life. Cyanosis is severe, progressive, and often accompanied by hypoxic spells characterized by increased cyanosis, dyspnea, and occasionally syncope. These spells may occur in the first 6 months and are a grave prognostic sign. In patients with increasing obstruction to pulmonary blood flow from progressive infundibular stenosis or VSD closure, cyanosis becomes rapidly more severe, and those who were previously acyanotic may become cyanotic in a matter of a few months. Clubbing of the fingers is common in children who survive beyond the first 2 years, but it may occasionally develop as early as 3 or 4 months. Squatting is uncommon, but dyspnea is often apparent with crying or feeding.

Most patients have loud, harsh, ejection systolic murmurs that are loudest over the lower left sternal border; these may be associated with an apical mid-diastolic rumble from large mitral valve flow. In cases of progressive obstruction to pulmonary flow, murmurs decrease or disappear. A continuous ductus arteriosus murmur may also be heard in patients with pulmonary atresia and occasionally in infants with pulmonary stenosis.

A minority of patients have no obstruction to pulmonary blood flow and a nonrestrictive VSD. These patients may present in infancy with signs and symptoms of excessive pulmonary blood flow, or they may have more or less normal Q ˙ p and only mild cyanosis. In the latter, physical findings, chest radiograph, and electrocardiogram (ECG) are similar to those of other patients with normal origin of the great arteries.

Patients in this subset of tricuspid atresia often present in early life with symptoms and signs of excessive pulmonary blood flow (see “ Clinical Findings ” under Clinical Features and Diagnostic Criteria in Section I of Chapter 33 ). Usually, an apical mid-diastolic rumble is heard, and there is fixed splitting of the second heart sound at the base. However, moderate subvalvar pulmonary stenosis occasionally results in either mildly increased or normal pulmonary blood flow. Such patients usually present after the neonatal period and sometimes after infancy, with mild cyanosis and few if any symptoms. Physical findings are similar to those in patients with tricuspid atresia and concordant ventriculoarterial connection. On the other hand, in the presence of subaortic stenosis and/or aortic arch obstruction, the neonate may have a duct-dependent systemic circulation and pulmonary overcirculation. These neonates may be very sick and present with severe congestive heart failure and systemic hypoperfusion. Their first stage palliation may require the Norwood operation (see Chapter 51 ).

The main (dominant) chamber making up the ventricular mass in double inlet ventricle with two ventricles may have a left ventricular internal architecture, a right ventricular internal architecture, or an indeterminate architecture. Main chamber volume is largest when there is no pulmonary stenosis but considerably smaller when pulmonary stenosis is present. This is related to the fact that main chamber volume is positively correlated with pulmonary-to-systemic flow ratio ( Q ˙ p/ Q ˙ s ). The nondominant, incomplete (rudimentary) hypoplastic chamber, when present, is always opposite architecture to the dominant chamber. Ventricular topology in double inlet ventricles may be either right-handed (D-loop), left-handed (L-loop), or indeterminate ( Tables 52.1 and 52.2 ). (See “ Symbolic Convention of Van Praagh ” under Terminology and Classification of Heart Disease in Chapter 27 ).

The nondominant chamber is called incomplete (or rudimentary ) because it lacks one or more of its component parts, usually the inlet portion but occasionally also the outlet, leaving only the apical trabeculated part. The incomplete chamber is always smaller than the dominant chamber and is connected to the dominant chamber by a VSD. The VSD is sometimes called a bulboventricular foramen, but this term applies only when the incomplete chamber is of right ventricular morphology. Rarely, such as when there is double inlet to one chamber and double outlet from the other, both chambers are incomplete. The ventricular septum is malaligned and incomplete in nearly all hearts with double inlet ventricle or is completely absent.

Some consider a solitary ventricle with double inlet to be an indeterminate ventricle, and some consider it to be an RV. ^,

Any type of atrial situs can be present. However, with DILV, there is usually atrial situs solitus, and with double inlet right and indeterminate ventricles, about half have situs solitus and half have a heterotaxy pattern, right atrial isomerism predominating (see Chapter 53 ). Situs inversus (mirror image) is unusual (see Tables 52.1 and 52.2 ).

There are usually two perforate AV valves positioned entirely in the dominant ventricle. Their morphologic characteristics are frequently indeterminate, neither tricuspid nor mitral, and it is therefore best to call them left-sided (draining the left-sided atrium) and right-sided (draining the right-sided atrium) ( Fig. 52.11 ). Alternatively, there may be a common AV valve ( Fig. 52.12 ), although this is rare in DILV. When the AV valve is a common one, valvar abnormalities are common, including important regurgitation.

Interior view of a specimen of double inlet right ventricle with anterior portion removed. There are separate right-sided and left-sided atrioventricular valves entering a thick-walled large ventricular chamber with right ventricular morphology. Ventriculoarterial connection is double outlet with aorta rightward and anterior above a prominent conus that is producing subaortic obstruction (arrow) . Ao, Aorta; LAV, left-sided atrioventricular valve; PT, pulmonary trunk; RAV, right-sided atrioventricular valve; RV, right ventricle.

Interior view of specimen of double inlet right ventricle, opened to expose structures as they would appear in a four-chamber imaged view. There is a common atrioventricular valve (CAV) entering the large right ventricular chamber and a large ostium primum atrial septal defect (complete atrioventricular septal defect). AS, Atrial septum; LA, left atrium; RA, right atrium.

In about 20% of cases, one of the perforate valves or the common valve overrides the remnant of ventricular septum, or the tension apparatus of one or both valves straddle the septum. Rarely, a common patent AV valve overrides or straddles the septum.

Atresia of an AV valve usually involves total absence of the AV connection, but occasionally there is an imperforate membrane with a miniature tension apparatus beneath it. ^{, ,} Typically (as in classic tricuspid atresia; see “ Morphology ” in Section II) the small, incomplete ventricular chamber is on the same side as the atretic valve, but it may be on the opposite side.

VA connections can be of any type, except in the case of a solitary ventricle, where there can only be a single or double outlet. In DILV, the most frequent connection is discordant, with aorta and subaortic incomplete RV (outlet chamber) to the left, but sometimes to the right, of the pulmonary trunk; concordant, double outlet, and single outlet connections occur ( Table 52.3 ).

Morphology of the AV node and conduction system is abnormal. Position of the AV node is determined primarily by whether the ventricular septal remnant reaches the crux (see “ Atrioventricular Node ” under Conduction System in Chapter 1 ). From the surgeon’s standpoint, it is important to know that the AV node can be anywhere around the perimeter of the right-sided AV valve.

Terminology of the coronary artery branches is arguable. Left and right coronary arteries usually arise from the two aortic sinuses facing the pulmonary trunk. There are usually prominent descending branches (encircling coronary arteries) that indicate points of attachment of septum to free ventricular wall, and therefore the boundaries of the incomplete ventricle. ^,

In DILV, the most common double inlet connection, the dominant ventricle is of left ventricular morphology. ^{, ,} Apical trabeculations beyond insertions of the papillary muscles display a delicate crisscross pattern. The septal surface is typically smooth in its superior half, and the crescentic margin bounding the VSD is smooth ( Fig. 52.13 ). VSD morphology, however, can be variable. Of 46 patients with DILV carefully evaluated by Bevilacqua and colleagues, 24 had VSDs separated from the semilunar valves and completely surrounded by muscle (muscular defects), 19 had VSDs adjacent to the anterior semilunar valve (subaortic defect) in association with malalignment or hypoplasia of the infundibular septum, and 3 had multiple muscular defects.

Interior view of specimen of double inlet left ventricle. Right-sided atrioventricular valve (RAV) is larger than the left-sided one (not completely visualized). The large ventricle has left ventricular morphology, with fine trabeculations near the apex and a smooth surface to the superior half of the ventricular septum (VS). There is a smooth crescentic lower margin bounding the ventricular septal defect. The incomplete right ventricle (RV) lies superiorly and leftward (L-loop). LAV, Left-sided atrioventricular valve; LV, left ventricle.

The small incomplete (rudimentary) ventricle is of right ventricular morphology, with coarse apical trabeculations and frequently a recognizable trabecula septomarginalis bounding the VSD anteriorly. A smooth-walled infundibulum is present when one or both great arteries arise from this chamber ( Fig. 52.14 ). Otherwise, and rarely, the chamber exists as a blind pouch. It is always positioned on the anterosuperior shoulder of the dominant LV ( Fig. 52.15 ), usually to the left but sometimes to the right. The septum thus lies obliquely and never extends to the crux.

Specimen of double inlet left ventricle with L-loop. Incomplete right ventricle (RV) has been opened, showing coarse trabeculae present in its inferior part and a restrictive ventricular septal defect (VSD). The aorta (Ao) arises from this chamber. LAA, Left atrial appendage; LV, left ventricle.

Frontal view of heart with double inlet left ventricle and L-loop. Specimen is the same as in Figure 52.14 . Incomplete right ventricle (RV) lies superiorly and to the left (on the shoulder) of the dominant left ventricle (LV). There is severe coarctation with hypoplasia of the transverse arch. Ao, Aorta; LAA, left atrial appendage; PT, pulmonary trunk; RAA, right atrial appendage.

The typical morphology of DILV, with ventricular L-looping, left-sided incomplete right ventricle, and VA discordant connections, occurs in about half of all cases, with a wide variety of VA connections in the remainder (see Table 52.3 ). The relatively uniform internal cardiac architecture of the AV valves and myocardium in typical DILV may be more variable when double outlet RV occurs with it. Atrial situs is usually solitus, occasionally ambiguus, but rarely situs inversus.

Two variants of DILV warrant further description: (1) DILV with ventricular L-loop, left-sided incomplete RV, and VA discordant connection and (2) DILV with ventricular D-loop, right-sided incomplete RV, and VA concordant connection.

In DIRV, both atria connect to a morphologic RV. Apical trabeculations are coarse, and the trabecula septomarginalis is recognizable on the septal surface, with the VSD contained between its anterior and posterior limbs. The incomplete LV is always positioned posteriorly and inferiorly (“in the hip pocket”) in relation to the main chamber and usually lies to the left (D-loop; Fig. 52.16 ) or rarely to the right (L-loop). More often than not, it is very small and slit-like, communicating with the main chamber by a tiny VSD, with no connection to a great artery. ^, In other cases, the LV is of reasonable size and the obliquely placed septum is well formed; in contrast to that in DILV, it extends superiorly to the crux. In these cases, fine apical trabeculations are recognizable, and the superior septal surface beneath the VSD is smooth.

Interior view of specimen with double inlet right ventricle and ventricular D-loop. There are two atrioventricular valves. The larger chamber has typical right ventricular morphology, and the diminutive incomplete left ventricle (LV) lies posteriorly and to the left (in the hip pocket). The ventricular septum (VS) is small. AS, Atrial septum; LA, left atrium; LAV, left-sided atrioventricular valve; RA, right atrium; RAV, right-sided atrioventricular valve; RV, right ventricle.

The VA connection is usually double outlet or single outlet (pulmonary atresia) from the RV ( Fig. 52.17 ; see also Fig. 52.11 ). A concordant connection sometimes occurs, with the aorta arising from the incomplete LV Pulmonary stenosis can be present.

Specimen of double inlet right ventricle and double outlet right ventricle. Arguably, the main chamber can be considered of indeterminate type rather than right ventricular. Ao, Aorta; LAV, left-sided atrioventricular valve; PT, pulmonary trunk; RAV, right-sided atrioventricular valve; RV, right ventricle.

Two AV valves may enter the large RV, with the left one straddling, or frequently a common AV valve. Atrial situs inversus, and particularly right atrial isomerism, is more common in DIRV than in DILV. DIRV associated with right atrial isomerism seems to be particularly prevalent in the Chinese.

In the presence of a D-loop and a ventricular septum reaching the crux, the AV node has its usual posterior position in the atrial septum with its normal relation to the ostium of the coronary sinus. The perforating bundle of His passes through the AV anulus and on to ventricular myocardium, either on the ventricular septum or on a trabecula on the posterior ventricular wall. In rare L-loop, the conduction system is variable, but a conventionally located AV node may be present, as well as a more rudimentary node located more anteriorly and superiorly along the right-sided AV anulus. The nonbranching bundle then descends onto a free-running trabecula in the main chamber.

Double inlet indeterminate ventricle includes hearts in which both atria connect to a solitary ventricle. Prevalence of this subset depends on the care with which a search is made for the possibility that the malformation is actually DIRV, because a tiny isolated accessory ventricular chamber may be missed by cardiac imaging and may be found only on careful autopsy examination. Even when the ventricle is truly solitary, it may represent a morphologic RV without a rudimentary LV, because apical trabeculations are always coarse, and there may be a freestanding column posteriorly reminiscent of the trabecula septomarginalis (see Fig. 52.17 ).

There is a higher prevalence of heterotaxy in double inlet indeterminate ventricle than in the other types of double inlet ventricle. With it, as well as with atrial situs solitus and inversus, two perforate AV valves are usually present. The only VA connection possible is double or single (pulmonary atresia) outlet ventricle. Pulmonary stenosis is common. The great arteries are often more or less normally related.

The AV node is usually posterior when there is a rudimentary ridge in the ventricle and distinct papillary muscles to both AV valves. In this case, the AV node passes down a free-running trabecula. When a ridge is absent, the AV node is usually situated laterally (away from the atrial septum) and anteriorly, and the nonbranching bundle descends into the right parietal wall of the indeterminate ventricle.

Rarely an apparently common (solitary) ventricle has no ventricular septum or a diminutive apical ridge, but importantly, one side of the ventricular mass is morphologically RV and the other morphologically left. Lev and colleagues consider this to be a heart with a huge VSD rather than double inlet common ventricle.

Left-sided AV (mitral) valve atresia with patent aortic outlet has a widely varying morphology. ^, All variants are discussed here, with one exception: mitral atresia with patent aortic outlet (aortic stenosis) with intact ventricular septum, atrial situs solitus, levocardia, single inlet RV with D-loop, and hypoplasia of all left cardiac segments, together with VA concordant connection. This variant is considered one of the four classic morphologic variants of hypoplastic left heart physiology, along with mitral atresia–aortic atresia, mitral stenosis–aortic atresia, and mitral stenosis–aortic stenosis (see “ Left Ventricle and Mitral Valve ” under Morphogenesis and Morphology in Chapter 51 ).

The atretic valve may be imperforate, in which case there is a hypoplastic membrane, sometimes with a miniature chordal apparatus beneath it; or the AV connection may be absent, with the floor of the atrium being separated from the ventricle by fibrofatty tissue. ^, In a study of 23 patients with patent aortic outlet and atresia of the left AV valve, 15 had absence of the left AV connection, 5 had an imperforate left AV valve, and 3 had atrial isomerism. Those with imperforate left AV valve demonstrated concordant AV connections.

The patent right-sided AV valve may occasionally override the remnant of ventricular septum, but with more than 50% of the anulus committed to the larger right ventricular chamber. The tension apparatus may straddle the septum, which reaches the crux.

In this most common arrangement (“mitral” atresia), there is atrial situs solitus, ventricular D-loop, and a dominant RV connected to the right atrium by a patent right-sided (usually tricuspid) AV valve and a small and incomplete LV lying posteriorly and to the left ( Figs. 52.18 and 52.19 ). The LV may be a blind chamber connecting to the RV by a small VSD (in which case the VA connection is either double or single outlet RV), but more commonly it functions as an outlet chamber giving origin to the aorta (concordant VA connection) and rarely to the pulmonary artery. The LV is often smaller than suggested by the position of the left anterior descending coronary artery (see Fig. 52.19 ). Characteristically, when the aorta arises from the small LV, the VSD is restrictive and the aorta small in association with coarctation or aortic arch hypoplasia. Interatrial obstruction is also common.

Specimens of hearts with left-sided mitral atresia but no aortic atresia in hearts with ventricular D-loop. (A) Posterior view of the atria, with atrial walls and septum displaced anteriorly and superiorly, except for septum primum. Arrow indicates site of atretic mitral valve. (B) External frontal view of another heart. Enlarged right ventricle (RV) is demarcated by anterior descending coronary artery (arrow) , although large branches extend over RV. Left ventricle (LV) is underdeveloped. (C) View of opened LV in same specimen as in (B). Midmuscular ventricular septal defects (VSD) and normally connected aorta (Ao) are seen. (D) Heart specimen opened to expose structures as they would be seen in a four-chamber view. Conoventricular and midmuscular VSDs are present. Ascending aorta and aortic valve (AoV) are normally connected to hypoplastic LV cavity. RV is enlarged and hypertrophied. (E) Close-up view of same specimen as in (D). Dimple at site of atretic mitral valve is indicated by arrow. Thickened septum primum is evident. LA, Left atrium; LAA, left atrial appendage; PT, pulmonary trunk; RA, right atrium; RAA, right atrial appendage; Sept 1, septum primum; TV, right-sided tricuspid valve; VS, ventricular septum.

Relation of left anterior descending coronary artery (LAD) to ventricular septum in hearts with mitral atresia and patent aortic root. Note that in this heart, the clearly visible artery is the LAD, which does not closely relate to the left ventricular (LV) cavity. LA, Left atrial cavity; PT, pulmonary trunk; RV, right ventricle.

(From Gittenberger-de Groot and colleagues. )

Alternatively, and less commonly, the arrangement is atrial situs solitus and ventricular L-loop with single inlet and more or less right-sided LV, in which case the right atrium is connected to the dominant LV by a patent AV valve with either mitral or indeterminate morphology. There is an incomplete left-sided RV situated anteriorly and to the left, above which is the atretic left-sided AV valve, and the VSD may be restrictive. The septum does not reach the crux. The usual VA connection is discordant with the RV giving origin to the aorta, but DOLV also occurs.

Excluding cases of classic right-sided (tricuspid) valve atresia (see Section II ), right-sided AV valve atresia can occur with single inlet and more or less left-sided RV (ventricular L-loop). Right AV valve atresia has also been reported in association with an indeterminate solitary ventricle. The patent left-sided AV valve may occasionally override the septum and may have multiple leaflets.

When one AV valve is regurgitant and the other is more or less normal in size and function, the regurgitant valve is closed, either before or as part of the Fontan operation. When both valves are competent and of adequate size, there has been concern that leaving both open will permit flow through each to be only half normal, and that this may encourage thrombosis in and around the valve. There is no strong support for this concern, however, and it appears reasonable at present to leave both open.

If one AV valve is closed surgically, it is usually the right-sided AV valve. Technique of closure must be secure and not produce heart block. Both criteria are met by polyester patch closure of the area occupied by the valve, sewing the patch in place with a continuous whipstitch of 4-0 polypropylene suture in a way that avoids heart block ( Fig. 52.27 ). This can be achieved by sewing the patch as shown in the figure, or by sewing it precisely to the valve anulus itself. Because the underlying AV valve can open and close beneath the patch, and because thrombi might form between patch and valve, a stitch is placed through the midpoint of the free edge of each leaflet and then through the center of the patch and tied on the atrial side. This is most conveniently done after placing the posterior half of the patch suture line. Simpler techniques of suturing together the free edges of the leaflets or suturing the patch to the leaflets themselves inside the hinge line have been associated with more dehiscences than the technique described.

Right atrioventricular (AV) valve may be closed as part of Fontan-type repair in double inlet left ventricle. Several possible locations of AV node and proximal bundle of His are shown. Because the location in a given patient is not known precisely, suture line for patch closure of right-sided AV valve is 5 mm outside anulus all the way around.

In a 1984 report overall hospital mortality after septation operation was high, about 30% to 40%. ( Table 52.4 ). However, among patients with moderate enlargement of the left ventricular main chamber without concomitant AV valve replacement or an extracardiac conduit, hospital mortality has been about 5%, but confidence limits are wide ( Table 52.5 and Fig. 52.34 ). In a 1997 report, overall hospital mortality was less than 10%. In the series by Margossian and colleagues, 2 of 11 (18%; CL 6.3%–38%) patients died. One death occurred in a two-stage repair that included an arterial switch, and the other in a one-stage repair. This improvement may reflect general progress in the field but may also be influenced by patient selection.

Survival after septation operation for double inlet ventricle without atrioventricular valve replacement and without valved extracardiac conduit, in patients with main chamber enlargement greater than grade II (patients are described in Table 52.6 ). Open circles represent deaths and vertical bars 70% confidence limits (CLs). Solid line represents parametrically estimated survival, and dashed lines enclose 70% CLs. Values in the table are from parametrically determined survival. Numbers in parentheses indicate number of patients available for further follow-up at the interval shown. (A) Survival. (B) Hazard function. There is only a single slowly declining hazard phase, which reaches a low level 5 years after septation.

(Data, except for subsequently updated follow-up, from McKay and colleagues. )

Historically, the early mortality has been high, with intermediate survival reported to be about 60% when all deaths, including those in hospital, are accounted for (see Fig. 52.34 ). Of importance when considering septation as an alternative to the Fontan operation, the single slowly declining hazard function for death after ventricular septation is low after about 5 years. In a more recent study of a 23-patient experience, midterm follow-up (3–11 years) showed an overall survival of 78%. In the 11-patient series of Margossian and colleagues, there was one late death with median follow-up of 2.3 years, with survival documented up to 8 years.

Shimada and colleagues reported on 22 patients (mean age 5.3 years) who underwent ventricular septation between 1978 and 1994. The actuarial survival was 49% at 30 years, with most survivors requiring some reoperation (reoperation-free survival of 21%). Late functional status in 8 patients was NYHA class I or II in 7 of the 8. The favorable late survival among those patients surviving the early phase is also supported by a report from Kurosawa and colleagues, who noted a 73% actuarial survival at 15, 20, and 25 years in a group of 34 patients with DILV undergoing a septation operation between 1971 and 2000.

Hospital deaths have usually been in acute heart failure and late deaths sudden or after reoperation (usually for AV valve replacement).

Within the group that currently is considered for ventricular septation (DILV, ventricular L-loop, left-sided incomplete RV with VA discordant connection, atrial situs solitus), no risk factors have been identified. However, unusual forms of double inlet ventricle, a small ventricular main chamber, concomitant AV valve replacement, and placement of a valved extracardiac conduit have been risk factors. Aside from morphologic factors, increasing age and ventricular hypertrophy have been identified as risk factors.

Functional status is generally good after ventricular septation. This might be expected from the experimental study by Seki, Tsakiris, and McGoon, which showed no demonstrable detrimental hemodynamic effect of replacing the dog’s ventricular septum (and tricuspid valve) with a prosthesis. It is also supported by detailed hemodynamic study of two patients late after ventricular septation by Shimazaki and colleagues. In one patient 8 years postseptation, both right and left ventricular ejection fractions were normal, as was hemodynamic response to exercise. Kurosawa and colleagues found cardiac indices to be higher after septation than after a Fontan operation.

However, late after a ventricular septation or Fontan operation, cardiorespiratory function by objective measurements at rest and during exercise is depressed when compared with normal. Evidence is contradictory as to whether ventricular septation provides better cardiorespiratory function than the Fontan operation. In one study, objectively measured postoperative exercise tolerance, compared with that preoperatively, was more improved after the Fontan operation than after ventricular septation, but in a later study, superior cardiorespiratory function was found after ventricular septation. In a more recent study of DILV patients comparing Fontan operation or ventricular septation, the ventricular septation patients with native AV valves demonstrated superior cardiopulmonary response to exercise compared with either Fontan patients or ventricular septation patients with prosthetic AV valves.

Complete heart block occurred after most ventricular septation operations in one series from 1982. However, in a series from 2002, only 1 of 11 patients (9.1%; CL 1.5%–28%) developed it. The difference may be that a running suture technique was used in the series with a low occurrence of heart block, rather than interrupted pledgeted mattress sutures that penetrate deeper into the myocardium.

Because in this subset, the patient most commonly presents with reduced pulmonary blood flow or with duct-dependent pulmonary circulation resulting from obstruction at or below the pulmonary valve, neonatal surgical palliation is required. This is achieved by some form of systemic–pulmonary arterial shunt designed to increase pulmonary blood flow and decrease cyanosis.

Occasionally, there is little or no obstruction at or below the pulmonary valve, and the patient presents with excessive pulmonary blood flow; surgical palliation to reduce it is required. This is achieved with a pulmonary artery band . On occasion, neonates present with either well-balanced or moderately increased pulmonary blood flow in which case neonatal surgical palliation may be avoided. Such patients need careful monitoring, because Rp can change rapidly in the first few weeks of life. Some patients will require a systemic–pulmonary arterial shunt if blood flow to the lungs decreases over time. Other patients will remain with relatively well-balanced pulmonary and systemic blood flow and may not require surgery until the second-stage superior cavopulmonary connection.

When there is little or no resistance across the VSD and right ventricular outflow tract, however, markedly increased pulmonary blood flow gradually develops. This usually is not a problem in the first week of life when resistance in the pulmonary microvascular bed remains somewhat elevated, but such patients eventually require a pulmonary artery band to establish appropriate balance between the systemic and pulmonary circulation. Careful consideration should be given to timing of pulmonary artery banding in such patients. It may be beneficial to delay placing the band until pulmonary blood flow increases somewhat, in concert with the normal postnatal decrease in Rp (see “ Timing of Pulmonary Trunk Banding ” under Indications for Operation later in this section).

In the setting of HLHS and its variants, additional special considerations are at play during the first-stage palliation (see Chapter 51 ).

Before undertaking any surgical procedure, overall cardiopulmonary stability should be ensured. These neonates are typically stable and come to the operating room breathing spontaneously and on little pharmacologic support other than, in some cases, prostaglandin E ₁ (PGE ₁ ) infusion to maintain ductal patency. However, if they present in an uncompensated state, either with overcirculation of the pulmonary circuit or with undercirculation and profound cyanosis, it is prudent to resuscitate them aggressively before operation. This may include use of PGE ₁ , inotropic agents, diuretics, mechanical ventilation with appropriate manipulations, nutritional support, and treatment of sepsis. Following stabilization, a period of observation is usually beneficial to allow recovery of systemic end-organ damage before surgical intervention. However, circumstances may require urgent operation despite inadequate resuscitation. For example, a previously undiagnosed and stable infant may present at several weeks of life with a recently closed ductus, resulting in ongoing critical cyanosis.

After anesthesia induction, an indwelling arterial catheter is placed, preferably in the left radial artery. Reliable intravenous access is achieved, preferably via peripheral extremity vein; subclavian and internal jugular veins should be specifically avoided because they tend to develop deep venous thrombosis that can importantly complicate subsequent management at the time of superior cavopulmonary shunt (see Section V ). It is similarly important to avoid femoral vein cannulation, because most patients with univentricular AV connection require multiple cardiac catheterization evaluations, preferably via the femoral vein.

The preferred incision for performing a systemic–pulmonary arterial shunt is median sternotomy. This incision has multiple advantages over traditional lateral thoracotomy:

• •

  Both lungs can be completely ventilated throughout the procedure. This can be especially important in unstable infants.

• •

  The shunt can be placed more centrally on the right (or left) branch pulmonary artery, thereby reducing prevalence of right or left upper lobe pulmonary artery branch stenosis. In patients with situs solitus, a shunt to the RPA is preferred as its length is significantly longer as it passes behind the aorta and the SVC. Furthermore, the LPA is shorter and dives early into the left hilum. Stenosis of the RPA, should it occur, is easier to repair at the time of the cavopulmonary anastomosis, which is not the case for the LPA.

• •

  Maximal flexibility is achieved.

• •

  If the ductus arteriosus is to be ligated during the shunt procedure, it can be accomplished effectively.

• •

  If central pulmonary artery stenosis at the site of ductus insertion is present or suspected, pulmonary arterioplasty can be performed.

• •

  If the patient becomes unstable during the procedure and requires CPB, there is access for cannulation.

• •

  Occurrence of musculoskeletal deformities induced by a lateral incision, such as scoliosis, is eliminated.

The single disadvantage of median sternotomy is risk of hemorrhage from inadvertent cardiotomy on repeat sternotomy at subsequent procedures. This can be minimized by leaving intact the anterior aspect of the pericardial sack overlying the ventricular mass at the first procedure.

Median sternotomy is performed (see “ Incision ” in Section III of Chapter 2 ). The typically large thymus gland is mobilized or partially removed, and only the upper pericardial reflection over the great arteries is opened, leaving intact the portion overlying the ventricular mass. Sites on both systemic and pulmonary circuits are chosen for placing the shunt (see “ Systemic–Pulmonary Arterial Shunt ” under Special Situations and Controversies later in this section). Usually a modified Blalock-Taussig-Thomas shunt is performed ( Fig. 52.39 ) using an expanded PTFE vascular graft of specified internal diameter, placed between the brachiocephalic–right subclavian artery junction, and central portion of the RPA (see “ Systemic–Pulmonary Arterial Shunt ” under Special Situations and Controversies later in this section). Systemic and pulmonary arterial sites are prepared using sharp dissection. The patient is heparinized (3 mg · kg ⁻¹ intravenously). An appropriately sized partial occlusion vascular clamp is used to isolate the brachiocephalic–right subclavian arterial segment, which is incised over a length appropriate to create an orifice that matches the expanded PTFE graft.

Right modified Blalock-Taussig shunt through median sternotomy. Although either anastomosis can be performed first, here the graft–right pulmonary artery (RPA) anastomosis is performed first, followed by the graft–subclavian artery anastomosis. (See text for description of procedure in opposite order.) (A) After median sternotomy, thymus gland is subtotally resected and pericardium opened along its upper aspect. Aorta is retracted to left side, and superior vena cava to right side, exposing RPA. Brachiocephalic artery and its bifurcation into right subclavian and carotid arteries are dissected cephalad to brachiocephalic vein. (B) Side-biting vascular clamp is placed on RPA in such a way that clamp itself holds aorta to patient’s left. Care is taken that incision in superior aspect of RPA does not encroach on its bifurcation into upper and lower branches, but is kept as central as possible. An appropriately sized polytetrafluoroethylene (PTFE) tube graft is then connected to RPA incision, using a continuous suture technique and 7-0 nonabsorbable monofilament suture (see text for a more detailed discussion of factors involved in determining choice of shunt size). Posterior aspect of anastomosis is performed first, followed by anterior aspect. (C) After the graft to pulmonary artery anastomosis is completed, a side-biting vascular clamp is placed on exposed right subclavian artery or right subclavian–brachiocephalic artery junction. Sequestered segment of artery is incised over an appropriate length to match circumference of PTFE tube graft. Graft is tailored to an appropriate length and beveled to avoid kinking or distorting subclavian and right pulmonary arteries. Anastomosis is performed using a technique similar to that described for graft-to–pulmonary artery anastomosis in (B). (D) Shunt is shown with anastomoses completed and aorta and superior vena cava in their normal positions. Additionally, ductus arteriosus has been ligated with a 5-0 polypropylene suture following blunt circumferential dissection with a small right-angled clamp.

Focus on detail is necessary to create a functional and reliable shunt. Attention is given to the angle of takeoff of the brachiocephalic artery origin and brachiocephalic-subclavian arterial junction. The expanded PTFE graft is tailored with a bevel to maximize laminar flow at the arterial graft anastomosis. Anastomosis is then performed with running 7-0 nonabsorbable monofilament suture.

After the anastomosis is completed, the partial occlusion clamp on the arterial segment is removed and replaced with a small clamp occluding the graft. This allows the arterial segment to assume its natural position, thereby permitting the surgeon to judge exactly the length of the graft in preparation for its anastomosis to the RPA. Attention to detail is necessary because a graft tailored to an inappropriate length may kink or distort the involved arteries. Typically, no bevel is necessary at the graft-RPA connection, and end-to-side anastomosis is performed at a 90-degree angle. After trimming the graft to an appropriate length, a partial occlusion clamp is placed on the central portion of the RPA that lies to the right of the ascending aorta and left of the SVC; it should not involve the right upper pulmonary artery. An incision of appropriate length is made in the sequestered segment of RPA, and anastomosis proceeds using a technique similar to that of the previous anastomosis. Before completing it, heparinized saline may be infused into the graft and pulmonary artery segments to flush remnants of blood that may have accumulated. The clamp is then removed from the RPA. Before removing the clamp on the shunt, the ductus arteriosus (if present) is exposed, and a heavy silk ligature with a snare is placed around it. The clamp is then removed from the shunt, and the snare on the ductus is gently tightened to occlude it.

A period of hemodynamic adjustment then ensues. The surgeon should pay careful attention to change in systemic arterial oxygen saturation (Sa o ₂ ) as indicated by pulse oximetry and by change in hemodynamics as indicated by heart rate and systolic, diastolic, and mean blood pressures. New steady-state values for these variables are judged against baseline conditions, which may vary among infants. In general, Sa o ₂ between 75% and 85% is considered acceptable. Sa o ₂ below this range should raise concerns about a technical problem with the shunt, an inadequately sized shunt, or unsuspected distal pulmonary artery problems. Sa o ₂ above this range should raise concern that the shunt is too large. This latter concern is heightened if systemic arterial diastolic blood pressure is less than 25 to 30 mmHg.

Once stability has been achieved, the snare is removed from the ductus, and it is permanently ligated. PGE ₁ infusion is stopped. Mediastinal drainage and closing the median sternotomy are as usual (see “ Completing Operation ” in Section III of Chapter 2 ).

Pulmonary trunk banding is usually performed via median sternotomy, lateral thoracotomy, or anterior parasternal incision. Median sternotomy is preferred for the same reasons described in the preceding text for placing a systemic–pulmonary arterial shunt; patient preparation is also similar. If the surgeon prefers a lateral thoracotomy or anterior parasternal incision, it is performed on the left side. In other patients with univentricular AV connection with conotruncal abnormalities that result in position of the pulmonary trunk to the right of the aortic root, a right lateral incision is chosen.

Preferred median sternotomy is performed as described in Chapter 2 , and the thymus gland is mobilized or partially removed. The pericardium is opened only at its superior border over the great arteries, with care taken to leave it intact over the ventricular mass. The tissue plane between ascending aorta and pulmonary trunk is developed over a limited area halfway between the sinutubular junction of the pulmonary trunk and origin of the RPA ( Fig. 52.40 A).

Pulmonary trunk (PT) band placement in neonate or young infant. (A) Anatomy of PT and aorta is shown in tricuspid atresia and normally related great arteries, exposed through the preferred standard median sternotomy. It should be noted that tops of pulmonary valve commissures (dotted lines) are within millimeters of origin of right pulmonary artery. Circumferential dissection around PT is purposefully limited to minimize potential for distal band migration. Opening between PT and aorta is only large enough to just allow passage of band. (B) After circumferential dissection, PT is stabilized and manipulated with forceps while a right-angled clamp is placed around it. A segment of band material (3-mm-wide strip of reinforced silicone rubber sheeting is preferred) is positioned around PT as shown. Care is taken to place band just distal to sinutubular junction but also proximal to origin of right pulmonary artery. (C) Band is appropriately positioned circumferentially. Ends of band are overlapped anteriorly, and medium-sized metal clips are placed to secure them. Successively lower clips are placed to adjust band tightness. Once band is appropriately tightened (see text for details), two separate 5-0 monofilament nonabsorbable sutures are placed at left and right lateral aspects of PT, attaching band to PT adventitia. This is performed to further minimize potential for distal band migration.

Aggressive dissection in this area is discouraged because it increases the chances of migration of the band over time. Once circumferential access to the pulmonary trunk is achieved, the band is placed around it. Choice of band material may vary; however, material that prevents important fibrosis and calcification and has a low risk of erosion into the pulmonary trunk should be chosen. Width of band material should be broad (at least 2.5 mm) to minimize erosion. Preferred choice of band is a 3-mm-wide strip fashioned from a relatively thick (0.3 to 0.4 mm) silicone rubber sheet. This material incites minimal reaction in surrounding tissues.

After placing the band around the pulmonary trunk ( Fig. 52.40 B), its free ends are secured together to create a circumferential ring ( Fig. 52.40 C). Formulas can be used to estimate the appropriate circumferential length, but individual physiologic variability usually dictates adjustments be made. Free ends of the band are initially secured together at a point that allows only minimal circumferential narrowing of the pulmonary trunk. Following this initial placement, two sutures are placed at points 180 degrees opposite each other on the circumference of the band, attaching the band to the adventitia of the proximal portion of the pulmonary trunk (see Fig. 52.40 C). These sutures prevent pressure-driven distal band migration on the pulmonary trunk. Migration is common if the band is not secured.

Once the band is positioned, but before it has been adjusted to its final circumference, it is prudent to temporarily place a catheter into the distal pulmonary trunk to measure pressure distal to the band. Difference in systemic arterial and distal pulmonary artery pressure (P pa ) provides an accurate assessment of band gradient. The surgeon then gradually reduces band circumference, evaluating both band gradient and Sa o ₂ as end points. Both vary depending on physiologic circumstances; however, a typical band gradient in a neonate will be in the range of 40 to 70 mmHg, and Sa o ₂ should range between 75% and 85%. Band circumference is adjusted by placing metal clips in the vicinity where the two free ends of the band were initially secured together (see Fig. 52.40 C). These clips are placed sequentially, with each subsequent clip placed just below the most recently placed one, gradually approaching the physiologic end points just described. Appropriately adjusting pulmonary blood flow with a pulmonary artery band can be somewhat difficult. This is because pulmonary blood flow occurs only in systole, and the band is a two-dimensional resistor with little length. As a result, small changes in band circumference result in marked resistance changes and, therefore, marked Q ˙ p changes. Because flow across the band occurs only in systole, Q ˙ p varies with changes in systemic arterial pressure. It is therefore critical that the anesthesiologist create circumstances during band adjustment such that systemic blood pressure approximates that expected in the awake infant. This can usually be achieved by appropriate choice of anesthetic and volume management.

Once the band is appropriately adjusted, an indwelling right atrial catheter and atrial and ventricular pacing wires are placed as described earlier in this section for the systemic–pulmonary arterial shunt. Mediastinal drainage and median sternotomy closure are as described in “Completing Operation” in Section III of Chapter 2 .

After completing the procedure, it is not necessary to reverse the heparin with protamine; instead, the heparin is allowed to metabolize slowly. Beginning on the first postoperative night, aspirin is given rectally (1 mg · kg ⁻¹ · day ⁻¹ ) to prevent thrombus formation in the shunt.

Some degree of hemodynamic instability and modest metabolic acidosis are common in the first few postoperative hours. It is prudent to support the patient over the first postoperative day with mechanical ventilation and close observation. Occasionally, low-dose inotropic support is indicated.

As pulmonary resistance gradually decreases after placement of a pulmonary trunk band, it is occasionally necessary to reoperate to tighten the band further. Need for readjusting it can be minimized by appropriately timing the initial banding (see “ Timing of Pulmonary Trunk Banding ” under Indications for Operation later in this section).

Early mortality for patients with tricuspid atresia and other types of univentricular communications and reduced pulmonary blood flow is less than 10% and similar to that for shunts performed for palliation of tetralogy of Fallot (see “ Interim Results after Classic Shunting Operations ” in Section I of Chapter 34 ). Under most circumstances, pulmonary artery distortion by the shunt is uncommon. However, a multicenter study from the Congenital Heart Surgeons Society noted a higher ongoing mortality following systemic-to-pulmonary artery shunting compared to pulmonary artery banding or bidirectional cavopulmonary shunt as the primary procedure for patients with tricuspid atresia. Higher mortality was associated with the ductus arteriosus remaining open, the need for concomitant main pulmonary artery intervention, or if the arterial saturation was low (< 75% on room air) after the procedure. However, a single center study by Alsoufi and colleagues did not find an increased risk with initial systemic-to-pulmonary artery shunt compared to other initial palliation for tricuspid atresia. By multivariable analysis, the only risk factors identified were genetic/extracardiac anomalies.

In patients who cannot subsequently have a Fontan operation, palliation has been good, and 5-year survival without definitive operation is about 90%. Intermediate time-related survival, including mortality of subsequent interventions, is about 85% at 10 years when the shunt is initially performed after the first few months of life. ^, Risk of dying is highest in the first few months following the shunt procedure. Then, after 5 to 10 years, in the absence of further surgical interventions, many patients begin to deteriorate. Of course, this process is accelerated if one is dealing with pulmonary atresia where the shunt is the only source of pulmonary blood flow as compared to pulmonary stenosis when there is a dual source. This is related to cyanosis, which is due to relative narrowing of the Blalock-Taussig-Thomas shunt commensurate with patient growth, as well as to left ventricular cardiomyopathy secondary to chronic volume overload, which worsens with time (see “ Cardiomyopathy ” under Natural History in Section I).

In the current era, early mortality of less than 5% should be expected. Outcome following pulmonary artery banding, like systemic–pulmonary arterial shunting, is somewhat influenced by the intracardiac anatomy. For example, with tricuspid atresia or DILV and discordant ventriculoarterial connection, the tendency for subaortic stenosis to develop or progress is a frequent and unfavorable sequel to the banding procedure (see “ Physiology and Presentation ” under Discordant Ventriculoarterial Connection later in this section). ^{, ,} Subaortic stenosis not only increases risk of death before definitive repair but also after the Fontan operation; this is due to the resulting increase in main ventricular chamber muscle mass and corresponding decrease in ventricular compliance.

Presence of severe cyanosis (Sa o ₂ < 70%–75%) early in life or of duct dependency are indications for performing a systemic–pulmonary arterial shunt. Causes for cyanosis other than decreased pulmonary blood flow (e.g., reversible lung disease, anemia, obstructive pulmonary venous connection) must be ruled out.

When pulmonary blood flow is excessive producing severe congestive heart failure in early life, pulmonary artery banding is indicated. If pulmonary blood flow is excessive to produce important heart failure in the early weeks of life, banding is not indicated.

If a pulmonary artery band is placed too early following birth when the Rp is still high, the surgeon will be limited by the patient’s cyanosis when attempting to tighten the band to an appropriate level. As Rp gradually decreases following pulmonary artery banding, it is commonly necessary to reoperate to tighten the band further. Such need for readjusting the band can be minimized by appropriately timing the initial banding. The ideal time varies based on individual physiologic characteristics, but the procedure is usually best performed in the second, third, or fourth week of life. In the physiologic setting of low Rp and relatively high pulmonary blood flow the situation is optimal for placing the band with an appropriate tightness that ensures long-term balance between pulmonary and systemic blood flow.

Systemic–pulmonary arterial shunts can be placed at alternate sites on the systemic and pulmonary arterial systems other than those described previously in this chapter. These alternative sites may be chosen for practical reasons relating to individual anatomy or simply surgeon preference. Anatomic variations that may determine site of the shunt include situs inversus, atrial isomerism, right-sided aortic arch, and abnormal arch branching patterns. In patients with small confluent central pulmonary arteries, it may be wise to construct the proximal anastomosis on the main pulmonary artery, if one is present, to avoid distorting or occluding either left or right pulmonary arteries. Regardless of site, the systemic–pulmonary arterial connection is performed using a specific length and diameter of extended PTFE tube graft (see text that follows).

Diameter of the expanded PTFE graft is the most important determinant of resistance within a systemic–pulmonary arterial connection and therefore is the prime regulator of pulmonafry blood flow. Other factors, such as graft length and site of origin on the systemic circulation, also influence resistance but to a lesser degree Q ˙ p (Poiseuille resistance relationships). Once the appropriate diameter is chosen for the graft, these other factors can be used in individual patients to help further regulate pulmonary blood flow to create the ideal balance between the systemic and pulmonary circulation. A 3.5-kg infant is typically well served using a 3.5-mm-diameter graft connected to the brachiocephalic–right subclavian arterial junction. A larger infant, or one who has particularly small pulmonary arteries or manifests physiology indicative of elevated Rp, might best be served by a similar 3.5-mm tube graft connected directly to the brachiocephalic artery or even ascending aorta. With these adjustments, resistance in the artery giving rise to the tube graft is reduced, and therefore overall resistance across the connection is less, compared with a graft constructed with a more distal (smaller diameter) systemic connection. On the other hand, a smaller infant or one who manifests physiology indicative of very low Rp preoperatively may best be served by a 3.5-mm-diameter graft connected entirely to the right subclavian artery. In this case, the subclavian artery contributes additional resistance to that of the tube graft. A 3-mm-diameter tube graft may be considered in particularly small infants, such as those with a body weight 2.5 to 3 kg or less (see “Type” in text that follows).

“Technique of Operation” in this section describes the preferred modified Blalock-Taussig shunt using an expanded PTFE tube graft. Systemic–pulmonary arterial shunts using direct arterial tissue-to-tissue connection, such as the classic Blalock-Taussig-Thomas shunt, direct ascending aorta–to-RPA connection (Waterston shunt), descending aorta–to–left pulmonary artery connection (Potts shunt), and central ascending aortic–to–main pulmonary artery connection, are rarely if ever used in the setting of normally developed branch pulmonary arteries. These connections all have disadvantages of unreliable regulation of pulmonary blood flow or high prevalence of pulmonary artery distortion.

There is no foolproof formula for choosing optimal shunt diameter and connection to create perfectly balanced pulmonary and systemic circulation. Careful evaluation of patient size, pulmonary arterial anatomy, and physiologic behavior of the pulmonary vasculature preoperatively, and the surgeon’s own experience, all are considerations when choosing size, site, and type of shunt that will best serve an individual patient. A surgeon who typically uses precise and accurate surgical technique will achieve a 3.5-mm orifice at systemic and pulmonary artery anastomoses when a 3.5-mm tube graft is used; one who typically uses less precise and accurate technique will likely create anastomoses at both sites that are smaller than the 3.5-mm tube graft. In this case, a surgeon may come to realize over time that a larger-diameter graft provides the appropriate degree of pulmonary flow.

Although the use of aspirin following shunt placement is widely practiced, until recently there has been little documented evidence of its efficacy. The recent multicenter study by Li and colleagues shows that risk of thrombosis and death are both lower when aspirin is used. The study involved a wide range of morphologic lesions, and aspirin daily dosage varied, with 80% of patients receiving 20 to 40 mg · day ⁻¹ . The efficacy of aspirin did not vary with dosage.

Occasionally, infants with tricuspid atresia have either hypoplasia or a discrete stenosis in the proximal left pulmonary artery in the region of the ductus arteriosus. This lesion will almost certainly become rapidly progressive once PGE ₁ infusion is stopped. It is usually prudent to address it at the initial shunt procedure. Individual judgment is required regarding the method of relieving the stenosis. A patch can be placed across the segment of concern ( Fig. 52.41 ), or the segment can be excised and the distal left pulmonary artery reattached to the side of the pulmonary trunk. Either technique can be performed without using CPB, allowing the shunt to perfuse the right lung only during left pulmonary artery reconstruction. Occasionally with more complex central pulmonary artery stenosis, CPB support is necessary to achieve satisfactory reconstruction.

Repair of periductal left pulmonary artery (LPA) stenosis in neonate. (A) Exposure of pulmonary trunk and LPA is shown through a median sternotomy. Ductus arteriosus insertion at site of LPA stenosis is evident. Dashed line represents incision that will be made for patch repair of hypoplastic segment. (B) After blunt circumferential dissection of ductus arteriosus, 5-0 polypropylene suture ligatures are placed on aortic and pulmonary artery ends of ductus, and it is ligated and divided. Typically, a right modified Blalock-Taussig shunt has already been performed to ensure pulmonary blood flow to right lung while LPA reconstruction is performed. Two vascular clamps isolate LPA. Care is taken to avoid injury to left phrenic nerve. Central clamp is placed at junction of LPA with pulmonary trunk, providing enough tissue sequestered between the two clamps such that entire stenosis can be addressed. LPA is opened with a longitudinal incision across stenotic area and extending well beyond stenosis on each side. This may require incising onto pulmonary trunk. An appropriately fashioned patch of expanded polytetrafluoroethylene is then used to augment LPA. Diameter of patch at maximal area of stenosis should be determined such that luminal area at stenotic point is 40% to 50% larger than normal LPA diameter. Patch is sewn into place beginning distally and moving centrally with a running 7-0 monofilament nonabsorbable suture. (C) Completed repair is shown, with a widely patent LPA lumen and undistorted lobar pulmonary artery branches.

Neonates with tricuspid atresia and ventricular arterial discordance may be acutely ill in a manner similar to those with HLHS; therefore, preoperative stabilization should be similar to that for patients with HLHS (see “ Definition ” and “ Preoperative Management ” in Chapter 51 ). Even when the VSD is large at birth, it may spontaneously narrow, and subaortic obstruction then becomes apparent.

This technique is described for tricuspid atresia and discordant ventriculoarterial connection with aortic arch obstruction, but is applicable to any patient with univentricular AV connection, aortic arch obstruction, and excessive pulmonary blood flow ( Fig. 52.42 ). The patient is positioned in right lateral decubitus position, and a standard left posterolateral thoracotomy is made through the fourth intercostal space (see “ Alternative Primary Incisions ” under Incisions in Section III of Chapter 2 ). Description of the arch repair is similar to that for isolated coarctation in the neonate (see “ Technique of Operation ” in Section I of Chapter 40 for details).

Repair of hypoplastic aortic arch and pulmonary trunk band placement via left thoracotomy. (A) Standard left posterolateral thoracotomy is performed through fourth intercostal space, and ribs are retracted. Adventitia overlying distal aortic arch and left pulmonary artery is shown. Positions of phrenic and vagus nerves are indicated. Large ductus arteriosus is noted, along with severe hypoplasia of aortic isthmus and moderate hypoplasia of distal aortic arch. Great arteries are in transposed position, with aorta anterior and pulmonary trunk posterior. Left lung has been deflated and retracted in an inferior direction. (B) Adventitia overlying distal aortic arch is opened and retracted with sutures. Aortic arch obstruction is managed in standard fashion for neonatal aortic coarctation (see Section I of Chapter 40 for full discussion of technical and management issues related to aortic arch obstruction in the neonate). After appropriate dissection of aorta and ductus, vascular clamps are placed, and ductus arteriosus is ligated and divided, as is hypoplastic aortic isthmus. All remaining ductal tissue is removed from descending aorta, and a longitudinal incision is made on undersurface of aortic arch (dashed lines) . Descending aorta is connected end to side to undersurface of aortic arch between left subclavian and brachiocephalic arteries. (C) Repaired arch with ligated and divided hypoplastic aortic isthmus and ligated and divided ductus arteriosus. (D) Inferiorly retracted lung is now repositioned with more direct posterior retraction to better expose proximal intrapericardial great arteries. Incision in pericardial sack is made anterior and parallel to phrenic nerve to expose proximal pulmonary trunk in preparation for placing pulmonary trunk band. Pulmonary trunk is carefully dissected in limited fashion just above tops of pulmonary valve commissures and below origin of right pulmonary artery (see Fig. 52.40 ). Identification of right pulmonary artery origin may be difficult from the left thoracotomy perspective. Using a small right-angled clamp, circumferential dissection is achieved and a 3-mm-diameter band, taken from a sheet of reinforced silicone rubber, is placed around proximal pulmonary trunk. Band is then tightened and secured to prevent migration, as described in Fig. 52.40 .

Following arch reconstruction, a longitudinal incision in the pericardium is made 1 cm anterior to the left phrenic nerve. Depending on extent of the thymus gland, modest mobilization of its left lobe may be necessary. Once the pericardium is opened, the pulmonary trunk is identified in the transposed position, posterior and to the left of the ascending aorta. (In patients with DILV and L-transposition, the pulmonary trunk is posterior and to the right.) The plane between adjacent walls of ascending aorta and pulmonary trunk are carefully dissected, gaining circumferential access around the pulmonary trunk midway between its sinutubular junction and origin of the RPA. The RPA origin is particularly difficult to visualize through a left thoracotomy incision; however, it must be carefully located before positioning the band. Following this, details related to placing and adjusting the band are similar to those described previously (see “ Pulmonary Artery Banding ” under Technique of Operation earlier in this section) for placing a pulmonary artery band through a median sternotomy (see Fig. 52.40 ).

This technique is described for tricuspid atresia and discordant ventriculoarterial connection with subaortic and arch obstruction but is applicable to all forms of univentricular AV connection with subaortic and arch obstruction ^, ( Fig. 52.43 ). After anesthesia induction, placing indwelling peripheral arterial and venous catheters, and supine positioning, a median sternotomy is performed (see “ Preparation for Cardiopulmonary Bypass ” in Section III of Chapter 2 ). The thymus gland is subtotally removed and the pericardium opened anteriorly over the heart. The plane between pulmonary trunk and ascending aorta is carefully dissected and the entire aortic arch mobilized, including the first 1 to 2 cm of each arch vessel. The central pulmonary artery, ductus arteriosus, and descending aorta to the level of the first pair of intercostal arteries are also mobilized. The patient is then prepared for CPB. If the aortic arch is hypoplastic but not preocclusive (>2–3 mm in diameter), adequate perfusion on CPB can be achieved by cannulating the aortic system alone using a 6F or 8F aortic cannula. ^, If the ascending aorta is of adequate size, it can be cannulated directly (as shown in Fig. 52.43 ), or alternatively, if it is hypoplastic, the base of the brachiocephalic artery can be cannulated. The arterial cannula (or cannulae) is secured in place with standard purse-string sutures and snares. If the aortic arch is interrupted or is in continuity but with preocclusive narrowing at the isthmus and coarctation, dual arterial cannulation of the proximal pulmonary trunk and the aortic system is performed. (This variation is not shown in Fig. 52.43 , but see “ Technique of Operation ” in Chapter 40 for a detailed description of cannulation technique and CPB management when the arch is interrupted.) Temporary occlusion of branch pulmonary arteries is achieved either with snares or vascular clamps if perfusion is performed through the pulmonary trunk and ductus arteriosus to the descending thoracic aorta.

Construction of proximal pulmonary trunk to aortic anastomosis (Damus-Kaye-Stansel operation), using continuous cardiopulmonary bypass (CPB), for complex systemic outflow tract obstruction. (A) Surgical exposure is through median sternotomy, with subtotal resection of thymus gland. Pericardium is opened widely with a longitudinal incision. Great arteries are transposed with a hypoplastic ascending aorta and aortic arch, aortic coarctation, and large ductus arteriosus. Pulmonary trunk is dilated. Great arteries and their branches are dissected in a fashion similar to that performed for interrupted aortic arch (see “ Technique of Operation ” in Section II of Chapter 40 ). Systemic arterial and right atrial cannulation sites for CPB are positioned so that procedure can be performed using continuous CPB. In this illustration, the systemic arterial cannula is placed within the aorta at base of brachiocephalic artery (see text for other sites of cannulation). Dashed lines indicate areas of transection or incision required to create proximal pulmonary trunk–to-aortic anastomosis and repair hypoplastic aortic arch. Standard, moderately hypothermic CPB is established, as are cardiac arrest and cardioplegic myocardial protection. In cases with aortic continuity, as shown, ductus arteriosus is ligated at its pulmonary artery end as bypass is begun. Once target core temperature is achieved on CPB, aorta is clamped as shown and cardioplegia delivered to myocardium. As aortic clamp is placed, systemic perfusion flow is reduced to 30 mL · min ⁻¹ · kg ⁻¹ to reflect reduced distribution of flow, which is limited to upper body. Aortic clamp is adjusted to a more superior and oblique position such that perfusion to brachiocephalic and left carotid arteries is unobstructed, and left posterolateral aspect of upper ascending aorta is easily accessible to perform arch reconstruction (see “ Technique of Operation ” in Section II of Chapter 40 ). Operation proceeds by first addressing aortic arch, and then by creating proximal pulmonary trunk–to-aortic anastomosis. All ductal tissue is removed from descending aorta and isthmus, as shown by dashed lines. Left posterolateral aspect of upper ascending aorta is incised along dashed line shown, and descending aorta is connected to ascending aorta end to side, using 7-0 monofilament absorbable suture and a continuous suturing technique. After arch reconstruction is completed, attention is turned to proximal pulmonary trunk–to-aortic reconstruction. Dashed lines on distal pulmonary trunk and on right lateral aspect of proximal ascending aorta represent incisions required to create this anastomosis. (B) Pulmonary trunk is transected between sinutubular junction and origin of right pulmonary artery. Opening in distal pulmonary trunk is closed with either a patch or a primary transverse closure using continuous suture technique. Proximal ascending aorta is incised longitudinally on its right lateral aspect beginning just above sinutubular junction and extending to superiorly placed aortic clamp. Proximal end of right lateral aortic incision is extended posteriorly in a circumferential direction at a 90-degree angle from original longitudinal incision to create a posterior aortic flap (inset) . Base of this flap is then connected to adjacent posteromedial circumference of transected pulmonary trunk. The anterior-anterolateral component of the aorta-to–pulmonary trunk connection is completed using a patch of pulmonary artery allograft tissue or glutaraldehyde-treated autologous pericardium. To complete the procedure, an appropriately sized expanded polytetrafluoroethylene tube graft is used to create a systemic–pulmonary arterial shunt from brachiocephalic–subclavian artery junction to proximal right pulmonary artery (see “ Systemic–Pulmonary Arterial Shunt ” under Technique of Operation in Section II). Completed reconstruction is shown.

Venous cannulation is through a purse string in the right atrial appendage. After cannulation, CPB is instituted and preferably carried out using continuous antegrade cerebral perfusion (see Fig. 52.43 ). Alternatively, some surgeons prefer to use circulatory arrest (see “ Technique in Neonates, Infants, and Children ” in Section IV of Chapter 2 ). These CPB management techniques are also discussed in detail in the description of the Norwood procedure for HLHS (see “ Norwood Procedure Using Continuous Perfusion ” under Technique of Operation in Chapter 51 ). In particular, the techniques described in Chapter 51 for performing continuous antegrade cerebral perfusion are widely applicable to all forms of neonatal arch obstruction with associated hypoplastic arch and ascending aorta. Once the target perfusion temperature is reached, antegrade cerebral perfusion established, and cardiac arrest induced with cardioplegia, the obstructed aortic arch is addressed, as described in Fig. 52.43 .

If the aortic arch is in continuity but hypoplastic, the aortic isthmus is ligated with a 5-0 polypropylene suture, and ductus and coarctation tissue distal to it are removed (see Fig. 52.43 A). A small vascular clamp can be placed across the descending aorta at the level of the first set of intercostal vessels to stabilize the aorta and deliver it into the anterior mediastinum. A longitudinal incision is made in the posterior aspect of the upper ascending aorta and proximal aortic arch (see Fig. 52.43 A), and the descending aorta is anastomosed to this incision with a running 7-0 monofilament absorbable suture, thereby repairing the arch obstruction ( Fig. 52.43 B). In the case of true aortic arch interruption, the isthmus ligature is not necessary, and arch repair otherwise proceeds as described.

With the arch obstruction addressed, antegrade cerebral perfusion is terminated and full-body bypass is again established (see “ Norwood Procedure Using Continuous Perfusion ” under Technique of Operation in Chapter 51 ). Attention is turned to the proximal main pulmonary artery–to–aortic anastomosis. This can be accomplished in several ways, one of which is described in detail in Fig. 52.43 B. Although unusual in neonates with tricuspid atresia, if preoperative evaluation suggests that potential or real obstruction exists at the atrial septum, the right atrium is opened during continuous bypass, and the septum primum is removed to create an unobstructed atrial communication. During this maneuver, the single venous cannula in the right atrium must be temporarily clamped, and cardiotomy suction devices used within the two vena caval orifices to provide exposure for the atrial septal resection. The right atriotomy is then closed with a running 6-0 polypropylene monofilament suture. Venous drainage via the right atrial cannula is then reestablished and rewarming begun.

An appropriately sized expanded PTFE tube graft is then used to create a modified Blalock-Taussig shunt (see Fig. 52.43 B). Details of the shunt procedure are similar to those described earlier in this section for isolated neonatal systemic–pulmonary arterial shunt.

Principles of rewarming and separation from bypass are those described in “Completing Cardiopulmonary Bypass” in Section III of Chapter 2 . Following separation from CPB, management considerations with regard to pharmacology, physiology, and sternal wound (immediate or delayed sternal closure) are the same as described in the management of HLHS following the Norwood procedure (see “ Special Features of Postoperative Care ” in Chapter 51 ).

The Norwood anastomosis used in this setting is a slight modification of the procedure used in first-stage repair of patients with classic hypoplastic left heart physiology. It combines the DKS anastomosis with extensive augmentation (enlargement) of the hypoplastic aortic arch and upper descending thoracic aorta (see Chapter 51 ). ^, It is important to emphasize that the augmentation patch used is of a slightly different shape from that described for the typical patient with HLHS. This is necessary because with either tricuspid atresia and discordant ventriculoarterial connection, or with double inlet ventricle with L-loop and discordant ventriculoarterial connection, orientation of the great arteries is different from that in patients with normally related great arteries (i.e., found in aortic atresia and other classic forms of HLHS).

This technique is described for patients with tricuspid atresia and discordant ventriculoarterial connection with subaortic obstruction at the bulboventricular foramen (VSD) or incomplete RV but is applicable to all patients with univentricular AV connection in whom the aorta arises from an incomplete ventricle. Other lesions that result in a similar problem include DILV with discordant ventriculoarterial connection and mitral atresia with concordant ventriculoarterial connection (see Section III ).

Patient preparation, median sternotomy, and cardiac exposure are similar to that described in the preceding text. In the unusual case that there has been no previous surgery, upon opening the pericardium, it is immediately noticed that aorta and diminutive RV are anterior. More commonly, previous surgery (including previous median sternotomy) has been performed. Caution should be exercised upon repeat median sternotomy, because the anterior aorta may be in close proximity to the posterior sternal table. The patient is prepared for CPB by placing purse strings in the ascending aorta just below the brachiocephalic artery origin and in SVC and IVC. Aortic and bicaval cannulation is then performed in standard fashion, the patient is placed on CPB, and moderate hypothermia is achieved. The aorta is clamped, and cardioplegia is administered through the aortic root (see “ Single-Dose Cold Cardioplegia in Neonates and Infants ” in Chapter 3 ).

The VSD is best approached through an incision in the incomplete ventricle (outlet chamber) just below the aortic valve ( Fig. 52.44 A). This incision is later closed by an enlarging patch. Alternatively, the VSD may be approached through the aorta; however, this exposure may be limited because the aortic valve and aorta are typically hypoplastic. ^, Some have considered the risk of surgically induced heart block to be high in this procedure, but risk is substantially reduced using currently available knowledge about the location of the conduction tissue. When the VSD is observed through an incision in the outlet chamber (morphologic RV), the relationship of the conduction system to the VSD is the same as with any conoventricular VSD, with the conduction tissue at the posterior inferior rim of the defect. This is true whether the underlying morphology is tricuspid atresia and discordant ventriculoarterial connection or double inlet single LV and discordant AV and ventriculoarterial connections. Confusion regarding this issue has arisen because the conduction system appears to be positioned on the “anterior” rim of the VSD when viewed from the perspective of the main ventricular chamber of either tricuspid atresia and discordant ventriculoarterial connection or DILV and discordant AV and ventriculoarterial connections. This confusion is the result of difficulty in conceptualizing the spatial arrangement of the two ventricular chambers and ventricular septum with this exposure, which involves an atrial incision, substantial rotation of the heart, and visualization of the VSD through an AV (typically mitral) valve.

Direct relief of subaortic obstruction in univentricular hearts with transposed great arteries. (A) Median sternotomy exposure and standard cardiopulmonary bypass technique using moderate hypothermia and cardioplegic myocardial protection are utilized. Longitudinal incision in subaortic area of incomplete right ventricular (RV) chamber is used to expose subaortic obstruction. (B) Internal anatomy of incomplete and hypoplastic RV chamber is shown. Dashed lines show incisions used to resect muscle that result in enlarging the ventricular septal defect (VSD). Wedge of full-thickness septal muscle between these two incisions is removed, taking care to avoid injury to adjacent aortic valve and underlying atrioventricular valve. Position of wedge resection is also designed to avoid conduction tissue positioned along posteroinferior rim of VSD, represented by open circles. (C) Incision in free wall of incomplete RV is closed with a patch designed to augment subaortic chamber. Patch material can be polyester, glutaraldehyde-treated autologous pericardium, or polytetrafluoroethylene. Care is taken to avoid injury or obstruction to major coronary branches running along free wall of incomplete RV during incision closure.

The preferred approach is a vertical incision made in the outlet chamber free wall directly in line with the course of the ascending aorta (see Fig. 52.44 A). This incision should be made only after all major coronary artery branches are identified, because the incision should not cut across any of these. Once the outlet chamber has been entered, the VSD is identified and a full-thickness wedge of septum is removed from the anterior and anterior apical aspects of the rim of the defect ( Fig. 52.44 B).

Obstructing muscle bundles within the outlet chamber are excised. The outlet chamber is enlarged by closing the ventriculotomy with an enlarging patch, typically of polyester or glutaraldehyde-treated pericardium, using running monofilament suture ( Fig. 52.44 C). The process of separation from bypass and chest closure is standard.

In early-era reports, both early and intermediate-term survival have been unfavorable in patients with single-ventricle physiology following initial coarctation repair, with or without pulmonary trunk banding, likely related to associated instability that accompanies single-ventricle physiology (see also “ Results of Repair of Coarctation in Patients with Other Major Coexisting Intracardiac Anomalies ” in Section I of Chapter 40 ). More recent reports show better early and midterm outcomes. Odim and colleagues reported no early mortality (0%; CL 0%–12%) and an 87% survival at mean follow-up of 68 months in a small group of patients undergoing aortic arch reconstruction and pulmonary trunk banding.

This procedure has historically carried a substantial early mortality (>25%). Although limited data are available for evaluating it, certain insights can be gained by comparing the DKS and shunt procedure with the Norwood procedure, because there are important parallels between them (see “ First-Stage Reconstruction [Norwood Procedure] ” under Results in Chapter 51 ). Regurgitation of the original aortic or pulmonary valve, either immediate or delayed (perhaps due to distortion of the great arteries), and hemodynamic instability relating to a pulmonary circulation arising from a systemic–pulmonary arterial shunt all can be problems if the DKS procedure is used in this setting. Despite high early mortality, intermediate-term results in hospital survivors appear to be good. ^{, ,}

Early mortality ranges from 0% to 35%. ^, Reports with better outcomes tend to be from more recent series. It should be expected that outcomes from the modified Norwood procedure will be somewhat better in this morphologic population compared with patients with aortic atresia and other forms of hypoplastic left heart physiology because of fewer morphologic risk factors.

Knowledge of results of this operation is incomplete because of the great heterogeneity of patients receiving it, relatively small experience with it, and lack of complete and long-term follow-up. ^, . Current hospital mortality is generally <10%.

When this subset of tricuspid atresia exists with important aortic arch obstruction but without evidence of clear subaortic obstruction, surgical management in the neonatal period is controversial. Some surgeons prefer to act on the established observation that presence of aortic arch hypoplasia increases the likelihood of subaortic obstruction, and in all such cases they perform a proximal pulmonary trunk–to-aortic connection (DKS anastomosis ^{, ,} ) with arch reconstruction, or a modified Norwood. ^, This approach has the advantage of removing uncertainty related to adequacy of left ventricular systemic outflow. Its disadvantages are magnitude and risk of the procedure, which usually involves a prolonged period of CPB, myocardial ischemia, and in many hands, cerebral ischemia. This risk is warranted if subaortic obstruction exists; it may not be warranted if in fact the equivocal subaortic region is adequate.

Thus, some surgeons prefer to make an individual evaluation of the subaortic region. If its morphologic characteristics suggest the LV-to-aortic outflow tract will be adequate, an isolated arch repair and pulmonary trunk band is performed. ^, The advantage of this approach is that CPB and organ ischemia are avoided, and complexity of the procedure minimized. Acute morbidity and mortality with this operation are clearly lower than with the former approach. The disadvantage, however, is that the subaortic region remains a concern. Therefore, careful and frequent evaluation of the subaortic region, beginning in the immediate postoperative period, must be undertaken.

Mild subaortic obstruction for a short period may not negatively affect function of the single ventricle. Recent evidence suggests that patients with subaortic gradients up to 40 mmHg for up to about a 6-month duration, who initially underwent pulmonary artery banding and only later DKS procedures, did not have negative effects on ventricular function or reduced candidacy for later Fontan.

Assessment of the subaortic area must be ongoing over the course of the patient’s life. If LV-to-aortic outflow obstruction develops, the patient must undergo one of several subsequent procedures to relieve it. If subaortic obstruction occurs in the first several months following aortic arch repair and pulmonary trunk banding, the most appropriate procedure is a proximal aortic–to–pulmonary trunk connection (DKS anastomosis) and systemic–pulmonary artery shunt. Before this procedure is done, the banded pulmonary trunk must be assessed carefully to confirm that no damage to the pulmonary valve has occurred from the band. Distortion or damage to the pulmonary valve resulting from the banding procedure may increase the chances of important neoaortic regurgitation following the proximal pulmonary trunk–to–aortic connection. When careful attention is given to technical details, competence of the native pulmonary valve can usually be preserved. ^, If the pulmonary valve is regurgitant, the only remaining surgical alternative is to incise and excise the obstructing subaortic muscle at the level of the VSD and hypoplastic right ventricular chamber. Such a procedure, however, carries an important risk of morbidity in the small infant or neonate with respect to ventricular function and conduction integrity.

If subaortic obstruction develops later in infancy following neonatal arch reconstruction and pulmonary trunk banding, proximal aortic to pulmonary trunk connection (DKS anastomosis) can be performed at the time of superior cavopulmonary connection, obviating need for a systemic–pulmonary artery shunt. Again, careful evaluation of the adequacy of the pulmonary valve must be undertaken, and the alternative of a subaortic muscle resection must be given consideration.

If subaortic obstruction develops in a patient who previously received arch reconstruction and pulmonary artery banding as a neonate, and who has subsequently undergone either a superior cavopulmonary shunt or a Fontan procedure, risk/benefit analysis of each of the two procedures that can be used to relieve the obstruction is substantially altered. Forward flow across the pulmonary valve is eliminated or markedly reduced at the time of the superior cavopulmonary shunt and must be eliminated at the time of the Fontan. If subaortic obstruction develops subsequently, long-standing lack of flow across the pulmonary valve, with stasis of the valve cusps, increases concern about its long-term function in the systemic circulation. Muscle resection to enlarge the VSD and subaortic region, although never without morbidity, becomes a more attractive option under these circumstances. In the larger patient, accurate resection at the level of the VSD may relieve obstruction with less risk of injuring the conduction system or major coronary branches in the septum.

Park and colleagues analyzed progression of subaortic stenosis in 30 patients with tricuspid atresia and discordant ventriculoarterial connection ( n = 10) or double inlet LV ( n = 20) and prior single-ventricle palliation. Overall freedom from left ventricular outflow obstruction at 5 years was 34.5%. Twenty patients (67%) required reoperation for left ventricular outflow tract obstruction during a median of 66 months. The most common reoperative procedures were DKS procedure in 12 and a Norwood-type palliation in 4. Risk factors for development of left ventricular outflow obstruction were initial aortic arch obstruction (HR 20.6, P =.003) and smaller systemic outflow tract area index at end-systole (HR 1.5 at 10 mm ² /m ² decrease, P =.033).

Early mortality after palliative procedures discussed in the text that follows should be low. Procedures should not interfere with, and indeed should facilitate, later Fontan operation, and they should provide good long-term palliation for patients in whom the completed Fontan operation is not possible.