VSDs are highly variable in size, and their division into size groups is arbitrary but useful. The echocardiographic criteria for VSD size are discussed in “Two-Dimensional Echocardiography” under Clinical Features and Diagnostic Criteria.

Large VSDs are approximately the size of the aortic orifice or larger. They offer little resistance to flow, and thus their VSD resistance index ¹ is less than 20 units · m ² in situations in which the calculation of the index is valid. ^, Right ventricular (RV) systolic pressure approximates left ventricular (LV) pressure, and the pulmonary to systemic blood flow ratio ( Q ˙ p/ Q ˙ s ) is increased to a degree dependent on the level of pulmonary vascular resistance (Rp).

Moderate-sized VSDs, although still restrictive, are of sufficient size to raise RV systolic pressure to approximately half LV pressure and Q ˙ p/ Q ˙ s to 2.0 or greater.

Small VSDs are of insufficient size to raise RV systolic pressure, and Q ˙ p/ Q ˙ s is not increased above 1.75. Small VSDs have a VSD resistance index greater than 20 units · m ² . Multiple small defects behave in aggregate as a large defect.

VSDs can occur in all portions of the ventricular septum ( Fig. 33.1 ). VSDs with entirely muscular borders (muscular VSDs) may occupy several areas of the ventricular septum. Other VSDs have one or several nonmuscular borders consisting of spaces or structures against which they are juxtaposed ( Table 33.2 ). These nonmuscular borders may be a semilunar valve, an AV valve, or the crux cordis (intersection of the posterior aspect of the interventricular septum and AV junction). Some VSDs in the periphery of the ventricular septum are bordered by the ventricular free wall, but such VSDs are conventionally considered to be muscular. VSDs in the category of subarterial may be (1) juxtaaortic , (2) juxtapulmonary , (3) juxtaarterial (bordered by both pulmonary and aortic valves), or (4) juxtatruncal (bordered by the valve of a common arterial trunk). Subarterial VSDs are typically associated with some degree of overriding of the related arterial trunk, and the margin of the VSD is actually a space over which is a semilunar valve(s).

Schematic representation of position of ventricular septal defect (VSD) as seen from right ventricular (RV) side of septum. Front of right ventricle, right atrium, and tricuspid valve have been removed. Shown are (1) doubly committed subarterial (juxtaarterial) VSD; (2) a perimembranous (conoventricular) VSD, which is juxtaaortic and juxtatricuspid; (3) an inlet septal VSD, which is juxtatricuspid and juxtamitral and, in this instance, juxtacrucial, a defect generally associated with atrial and ventricular septal malalignment and overriding tricuspid valve; and (4, 5, 6) trabecular VSDs. In positions 5 and 6, VSDs tend to be small and multiple, and when most of this trabeculated area and midmuscular septum are peppered with holes, the term Swiss cheese defect is used. Position 5 would be classified muscular, outlet type ; position 6 is muscular, apical . A, Aorta; c, conal (outlet, infundibular) septum; IVC, inferior vena cava; M, membranous septum with ventricular and atrioventricular portions; NC, noncoronary aortic cusp; P, pulmonary trunk and valve; R, right coronary artery cut off at its origin; SVC, superior vena cava; TS, trabecula septomarginalis (septal band); V, muscular portion of atrioventricular septum.

Many VSDs are associated with malalignment of portions of the ventricular septum or atrial septum relative to the interventricular septum, in which case an AV valve usually overrides the VSD. Malalignment VSD terminology results from two-dimensional (2D) echocardiographic examination of the heart regarding alignment of the trabecular and the outlet (conal) septum. In some cardiac anomalies, the aorta seems displaced relative to the VSD. The malalignment is referred to as anterior when the outlet septum appears anterior to the trabecular septum, with the VSD interposed. Tetralogy of Fallot–type defects are considered anterior malalignment types, with the aorta “overriding” the VSD (see Fig. 33.2 ). Malalignment is posterior when the outlet septum appears posterior to the trabecular septum in anomalies such as interrupted aortic arch and severe coarctation of the aorta. There may also be a rotational malalignment in anomalies characterized under the broad category of Taussig-Bing heart, a variation of double outlet right ventricle (DORV) with subpulmonary VSD or in transposition of the great arteries with VSD.

Two-dimensional echocardiograms with Doppler directional flow velocity in perimembranous ventricular septal defect (VSD) . (A) Four-chamber view demonstrating VSD as gap in ventricular septum between right ventricle and left ventricle. (B) Magnified view of VSD. (C) Turbulent blood flow through VSD is directed from left ventricle to right ventricle.

Anatomic location of the VSD determines its relation to the conduction system.

In DORV, VSDs may also be characterized according to their commitment to the great arteries (Lev and colleagues ): subaortic, subpulmonary, doubly committed, and noncommitted. This type of characterization—which is relational, not morphologic—preferably is restricted to hearts with double outlet ventricles, because its use in other situations has resulted in considerable confusion.

All these features of the location of VSDs should be included in descriptions of these defects.

Approximately 80% of patients operated on for primary VSD have a perimembranous VSD. ^{, ,} These defects could be called junctional VSDs because they are in the junctional area between the trabecular (sinus) and outlet (conal) portions of the ventricular septum ( Fig. 33.3 ) and usually appear to be between the posterior and anterior divisions of the trabecula septomarginalis (septal band). Thus, these VSDs are between the outlet (conus) and inlet (ventricular) portions of the right ventricle, but characteristically they are in the outlet portion of the left ventricle.

Perimembranous ventricular septal defect (VSD) viewed from right ventricle. VSD borders anteroseptal commissure of tricuspid valve (juxtatricuspid) and has anterior extension to VSD and midportion of muscular septum. InfS, Infundibular (outlet) septum; PV, pulmonary valve; TV, tricuspid valve.

Perimembranous VSDs are often associated with anomalies of the outlet septum and other adjacent structures, although when small they may be truly isolated anomalies. Most perimembranous VSDs are juxtatricuspid (abutting the tricuspid valve), juxtamitral, and juxtaaortic . These perimembranous VSDs are also conoventricular (conotruncal) ( Fig. 33.4 ). Such defects abut the commissural area between the noncoronary and right coronary cusps of the aortic valve. Others are only juxtatricuspid ( Fig. 33.5 ), and in hearts with these as well as in hearts with perimembranous VSDs, the bundle of His passes along the posteroinferior border of the defect. Some perimembranous VSDs abut none of these valvar structures and are separated from the tricuspid anulus posteriorly by a band of muscle that is part of the posterior division of the trabecula septomarginalis joining with the ventriculoinfundibular fold. The bundle of His is not in this muscular band but is in its usual position more posteriorly. Technically, although this type of defect is located in a perimembranous position, it is better classified as muscular inlet–type VSD because all borders are muscle.

Large perimembranous ventricular septal defect, viewed from right ventricle (RV) (A) and left ventricle (B). In (A), septal tricuspid leaflet was folded back into right atrium after its chordae were cut. Arrows indicate areas of tricuspid-mitral continuity, and defect borders tricuspid valve; it is juxtatricuspid, juxtamitral, and juxtaaortic. This defect, viewed from RV, lies far to the right in aortic margin of ventricular septum and thus is beneath the commissure between noncoronary and right coronary cusps. Defect is perimembranous, and no muscle is between it and anterior septal tricuspid commissure. Conal septum is hypoplastic but not malaligned. AO, Aorta; LV, left ventricle; MV, mitral valve; NC, noncoronary cusp; PV, pulmonary valve; RC, right coronary cusp; TV, tricuspid valve.

(From Soto B, Ceballos R, Kirklin JW. Ventricular septal defects: a surgical viewpoint. J Am Coll Cardiol . 1989;14:1291.)

Perimembranous ventricular septal defect (VSD) of moderate size. (A) VSD in region of anteroseptal commissure of tricuspid valve, viewed from right ventricle. VSD extends inferiorly beneath septal leaflet of tricuspid valve and abuts commissural area between anterior and septal tricuspid leaflets (juxtatricuspid) and remnant of membranous septum. Numerous tricuspid chordae and papillary muscles (arrows) are present. (B) Same defect viewed from left ventricle. VSD lies below noncoronary cusp of aortic valve and is not juxtaaortic. Arrow indicates cleft in anterior mitral leaflet. ALMV, Anterior leaflet of mitral valve; AV, aortic valve; LV, left ventricle; PV, pulmonary valve; RA, right atrium; SLTV, septal leaflet of tricuspid valve.

VSDs have also been described in the past as typically high, infracristal, membranous, or perimembranous, without the original specific description. ^{, , ,}

As already indicated, the AV node and penetrating portion of the bundle of His are in their normal position in hearts with perimembranous VSDs. As the bundle penetrates the fibrous right trigone of the central fibrous body at the base of the noncoronary cusp of the aortic valve, it lies along the posteroinferior border of perimembranous and inlet-type VSDs. As the bundle continues along the inferior border of the VSD (at times slightly to the left or right of the free edge), the left bundle branch fascicles emerge from the branching portion. Only the right bundle branch remains when the bundle reaches the level of the muscle of Lancisi.

Abnormalities of the ventricular portion of the membranous septum are often associated with perimembranous VSDs. The membranous septum may be absent or nearly so, and then the right trigone (beneath the nadir of the noncoronary aortic valve cusp) and base of the septal and anterior leaflets of the tricuspid valve are exposed and form the posteroinferior rim of the VSD (see Fig. 33.4 ). The bundle of His, as it penetrates the fibrous right trigone at the base of the noncoronary cusp, is intimately related to the posteroinferior angle of such a defect. This is associated with a deficiency in the posterior limb of the trabecula septomarginalis. Rarely the ventricular portion of the membranous septum may be well developed, thickened, and perforated by one or many holes, forming an aneurysm of the membranous septum that bulges toward the right in systole. This so-called aneurysm is simulated on angiography by the much more common tethered anterior leaflet and the involved and usually fused chordae. Accessory fibrous tissue that is not part of the tricuspid valve mechanism may lie along the posterior or superior margin of the defect. This phenomenon is most marked in the flap valve VSD .

Not surprisingly, in hearts with perimembranous VSDs, still other adjacent structures may be abnormal. The medial papillary muscle characteristically joins the anteroinferior angle of the defect and receives chordae from adjacent portions of the tricuspid anterior and septal leaflets. These chordae may be increased in number and abnormally positioned around the edges of a perimembranous VSD, attached to the posterior edge, superior edge ( Fig. 33.6 ), or most often anterior edge. A thick leash of chordae joining the center of the anterior edge of a large defect may produce an appearance on angiography or even at operation of a double defect. Chordae from the anterior leaflet may attach to all three margins, and the anterior leaflet then limits the shunt from left to right through the defect, as well as hinder its repair.

Perimembranous ventricular septal defect (VSD) associated with anomalous leaflet tissue. (A) VSD viewed from right ventricle. Note chordal attachment (arrow) of anterior tricuspid leaflet to anterosuperior margin of defect. Normal position of infundibular (outlet) septum between two limbs of trabecula septomarginalis (septal band) is well seen. (B) Same defect viewed from right atrium. VSD is partly obscured by tricuspid leaflet tissue, but its extent is indicated by dashed line. (C) Same defect viewed from left ventricle. VSD is immediately beneath aortic valve (juxtaaortic), and its extent is indicated by dashed line. Abnormal tricuspid valve attachments are obvious and on an angiocardiogram are indistinguishable from an aneurysm of the membranous ventricular septum. ALMV, Anterior leaflet of mitral valve; AV, aortic valve; InfS, infundibular (outlet) septum; PV, pulmonary valve, RA, right atrium; RV, right ventricle; TS, trabecula septomarginalis (septal band); TV, tricuspid valve.

Close association of some perimembranous VSDs with the commissure between anterior and septal tricuspid leaflets sometimes results in adherence of leaflet tissue to edges of the defect and shunting directly from left ventricle into right atrium ^, ( Fig. 33.7 ). This so-called Gerbode defect or LV–right atrial defect, is rare constituting fewer than 5% of perimembranous VSDs in this region, and rarely involves the AV septum. An additional reason that a Gerbode defect can occur is due to the offsetting between the tricuspid and mitral valves, allowing a communication between the left ventricle and right atrium. Adherence of tricuspid leaflet and chordal tissue is also an important mechanism of spontaneous closure of these VSDs.

Type of perimembranous ventricular septal defect (VSD) that ejects directly into right atrium, a so-called left ventricular–right atrial defect. (A) VSD viewed from right atrium. Posterior part of tricuspid anulus is marked by dashed line. Tricuspid septal leaflet is anomalously adherent to underlying ventricular septum and edges of VSD, which is juxtatricuspid. Intact atrioventricular septum lies on atrial side of tricuspid anulus (beneath letters VSD ). Bundle of His is along posterior angle of defect. (B) Same defect viewed from left ventricle. VSD is juxtaaortic and beneath commissure between right and noncoronary aortic cusps. ALMV, Anterior leaflet of mitral valve; ALTV, anterior leaflet of tricuspid valve; LV, left ventricle; NC, noncoronary aortic cusp; RA, right atrium; RV, right ventricle; SLTV, septal leaflet of tricuspid valve.

Some 5% to 10% of patients treated operatively have a single VSD, usually of moderate or large size, within the outlet portion of the right ventricle. VSDs in this location are also in the outlet portion of the left ventricle and, in contrast to perimembranous VSDs, are located beneath the right aortic cusp. In the past, these have also been termed conal, infundibular, supracristal, subpulmonary , and intracristal defects. The complex morphology of the ventricular septum in the outlet portion of the right ventricle and many controversies concerning the term “outlet septum” support use of a simple descriptive terminology for this group of VSDs.

VSDs in this general location are bordered in part by a space over which lie the pulmonary and aortic valves ( Fig. 33.8 ). As such, these VSDs are subarterial. VSDs of this type are more common in Asians than in White or Black races. Subarterial VSDs may be circular, diamond shaped, or oval with the long axis lying transversely ( Fig. 33.9 ). When viewed from the LV aspect, these defects are in the outflow portion of the ventricular septum (see Fig. 33.8 B), beneath the right coronary cusp (or commissure between it and the left cusp). The aortic and pulmonary valve cusps are separated by only a thin rim of fibrous tissue, resulting in decreased support for the aortic valve. The right aortic cusp and (less often) noncoronary cusp may prolapse into the upper margin of the defect, with or without aortic regurgitation (see Section II later in this chapter).

Doubly committed subarterial ventricular septal defect (VSD) in outlet portion of ventricular septum. (A) VSD viewed from right ventricle. Its inferior margin is formed of thick septal tissue and its superior margin by confluent right pulmonary and right aortic cusps, which are separated by a thin ridge of fibrous tissue. (B) Same defect viewed from left ventricle. VSD is beneath right coronary cusp of aortic valve and more anterior than a conoventricular VSD. ALMV, Anterior leaflet of mitral valve; InfS, infundibular (outlet) septum; L, left pulmonary cusp; NC, noncoronary aortic cusp; R, right pulmonary cusp; TSM, trabecula septomarginalis (septal band).

Doubly committed subarterial ventricular septal defect (VSD) viewed from right ventricle. VSD lies immediately beneath pulmonary valve (and, although it is unseen, aortic valve). Inferior to defect are infundibular septum and trabecula septomarginalis (septal band). Tricuspid valve, papillary muscle of conus, and bundle of His are far from defect. InfS, Infundibular septum; PMC, papillary muscle of Lancisi; PV, pulmonary valve; TSM, trabecula septomarginalis (septal band); TV, tricuspid valve.

The posteroinferior margin of RV outlet VSDs is usually well separated from the tricuspid valve anulus by a band of muscle and is consequently well above the bundle of His. Occasionally, however, a particularly large confluent VSD may be both subarterial and perimembranous ( Fig. 33.10 ). The conduction system is related to such a VSD as it is to other perimembranous defects. This particular type of VSD is sometimes associated with severe overriding of the aorta over the right ventricle, and the cardiac anomaly is then termed double outlet right ventricle (DORV) with doubly committed VSD . The same type of VSD may also be seen in double outlet left ventricle (DOLV), in which the pulmonary artery severely overrides the VSD and the left ventricle.

Large confluent ventricular septal defect (VSD) that is both subarterial and perimembranous, extending downward to reach tricuspid anulus. This type of VSD is also seen in double outlet right ventricle with doubly committed VSD and in double outlet left ventricle. (A) VSD viewed from right ventricle. At superior margin of VSD, pulmonary and aortic cusps are in fibrous continuity. Arrow points toward aortic valve. (B) Same defect viewed from left ventricle. Note additional small trabecular muscular defect. Ao, Aorta; IS, infundibular septum; PA, pulmonary artery; PV, pulmonary and aortic cusps.

Morphology of these subarterial VSDs has been well elucidated by 2D echocardiography and color Doppler examinations. ^, Despite the potential confusion of using Lev’s relational terminology in a morphologic sense, in the echocardiographic literature, subarterial defects are usually referred to as doubly committed VSDs . Thus, it is useful to combine morphologic and echocardiographic descriptions to characterize these VSDs occurring in the RV outlet as doubly committed subarterial VSDs . Echocardiography has demonstrated that aortic and pulmonary valves are frequently at the same level in the presence of subarterial (or doubly committed) VSDs, rather than the pulmonary valve being elevated above (cephalad to) or offset relative to the aortic valve, seemingly by the RV infundibulum. This description often provides a diagnostic tool useful in both echocardiography and angiography, along with the finding that the outlet septum appears to be absent and the subpulmonary infundibulum deficient. Echocardiography has also demonstrated the frequently associated prolapse of an aortic cusp and aortic regurgitation present in up to half of patients with this type of VSD. Aortic cusp prolapse may nearly close the VSD during diastole. At times the fibrous raphe between the arterial valves is displaced relative to the ventricular septum, resulting in overriding of one arterial valve and narrowing of the other.

Some VSDs in the RV outlet are only juxtaaortic and abut the nadir of the right coronary cusp. The cusp typically prolapses through this type of VSD, and aortic regurgitation frequently develops. Rarely, VSDs in the RV outlet are only juxtapulmonary and lie far to the left.

Some defects in the outlet portion of the septum have muscular borders and lie in the substance of the infundibular septum (muscular VSD, outlet type), with a muscle bridge of infundibular septum superior to the defect. The superior muscular bridge may be malaligned and displaced leftward into the aortic outflow tract (posterior malalignment type of VSD), producing muscular subaortic stenosis that lies above the VSD. This anomaly occasionally occurs in association with interrupted aortic arch and with coarctation, although perimembranous VSDs are more common in both settings.

Five percent or less of surgical patients have inlet septal VSD (or AV septal type or AV canal type of VSD). This defect usually spans the entire RV inlet septum beneath the tricuspid septal leaflet and LV outlet septum . Its posterior margin is formed by the exposed AV valve anulus (juxtatricuspid), and its anterior margin is muscular and crescentic ( Fig. 33.11 ). Superiorly, inlet septal defects usually extend to the membranous septum. The AV septum is intact, in contrast to the situation in hearts with AV canal septal defects (see “ Morphology ” in Chapter 32 ). The anterior (septal) mitral leaflet occasionally may be cleft, either partially or completely, with associated mitral regurgitation. Rarely, VSDs in the inlet portion of the septum extend completely to the crux cordis and thus are also juxtacrucial in position. The tricuspid valve is overriding and usually straddling.

Inlet septal ventricular septal defect (VSD) beneath septal leaflet of tricuspid valve. Posterior margin of defect is formed by tricuspid anulus. VSD is juxtatricuspid. (A) VSD viewed from right ventricle. Note crescentic anterior margin of defect. (A previously placed polyester patch has been removed). (B) Same defect viewed from left ventricle. Superiorly, defect reaches almost to aortic valve; posteriorly, it extends to mitral valve. AV, Aortic valve; MV, mitral valve; PV, pulmonary valve; RA, right atrium; SLTV, septal leaflet of tricuspid valve; TV, tricuspid valve.

In inlet septal VSDs, the AV node lies more laterally and anteriorly along the tricuspid anulus than normal and at the point at which the tricuspid anulus meets the underlying ventricular septum, because of straddling of the tricuspid valve. The bundle of His lies along the posteroinferior rim of the inlet septal VSD, slightly on the LV side, as in juxtatricuspid VSDs.

A muscular VSD can occur in the inlet portion of the ventricular septum beneath the tricuspid septal leaflet ( Fig. 33.12 ). The posterior margin of such a defect is separated from the tricuspid ring by muscle. A muscular VSD must be distinguished from the inlet septal type of VSD because the conducting tissue runs superior and anterior to a muscular defect.

Single, moderate-sized, muscular inlet septal ventricular septal defect (VSD) lying beneath tricuspid septal leaflet. (A) VSD viewed from right ventricle. Note septal muscle between VSD and tricuspid valve. Bundle of His lies superior to VSD. This defect can easily be closed from a right atrial approach. (B) Same defect viewed from left ventricle. VSD is in posterior part of nontrabeculated portion of left side of ventricular septum. ALMV, Anterior leaflet of mitral valve; AV, aortic valve; LV, left ventricle; PV, pulmonary valve; TV, tricuspid valve.

VSDs in other locations are generally muscular VSDs. Such defects are frequently multiple and may be associated with perimembranous or subarterial VSDs. Single or multiple muscular defects in the trabecular septum are more common in infants requiring operative treatment than in older children.

Muscular defects can occur anywhere in the ventricular septum (see Fig. 33.1 ). Those in the middle portion of the trabecular septum are the most common ( Fig. 33.13 ) and may be overlaid by the trabecula septomarginalis; thus, even when single on the LV side, these defects have at least two openings on the RV side. Anterior muscular defects are usually multiple and most often in the apical and outlet portions of the septum. They may extend all along the anterior part of the septum from apex to outlet septum. Typically there are more openings on the RV than LV side.

Muscular trabecular septal ventricular septal defect (VSD) . (A) VSD viewed from right ventricle (RV). VSD is actually a single one, but is covered by trabecula septomarginalis (septal band) and therefore has two openings into right ventricle (see probes). (B) Same defect viewed from left ventricle. VSD, appearing more slit-like than it actually is, lies at junction of smooth and trabeculated portions of septum. This defect can be closed from RV, provided lower end of septal band is detached. ALMV, Anterior leaflet of mitral valve; AV, aortic valve; InfS, infundibular septum, or crista supraventricularis; PMC, papillary muscle of Lancisi; PV, pulmonary valve; TS, trabecula septomarginalis (septal band); TV, tricuspid valve.

A particularly important group of patients are those with Swiss cheese defects ( Fig. 33.14 ), many defects of variable size, not only along the anterior portion of the septum but throughout the midportion as well. These defects often pass obliquely through the septum to appear on both sides of the trabecula septomarginalis or in the anterior part of the septum. They may be associated with large or small perimembranous or subarterial defects. Major associated cardiac anomalies are common, especially severe coarctation of the aorta.

“Swiss cheese” type of multiple ventricular septal defect (VSD) associated with a large perimembranous VSD. (A) VSDs viewed from right ventricle. Perimembranous defect shows anomalous chordal attachment from tricuspid valve to posterosuperior margin of defect (arrow) . Probes demonstrate five separate openings of small defects, one above and four below trabecula septomarginalis (septal band). (B) Same defects viewed from left ventricle. Perimembranous defect is seen. Probes demonstrate three separate openings of Swiss cheese defects, but many more lie in grossly trabeculated lower portion of septum. ALMV, Anterior leaflet of mitral valve; AV, aortic valve; InfS, infundibular septum; PV, pulmonary valve; TV, tricuspid valve.

The bundle of His is not closely related to the borders of any muscular VSD.

Some unusually large, single confluent VSDs involve more than one area of the septum. Rarely a confluent VSD may involve most of the septum ( Fig. 33.15 ), but hearts with such defects should not be classified as having a single ventricle.

Large confluent ventricular septal defect (VSD) is perimembranous and occupies upper half of muscular septum beneath infundibular septum (anterior extension). It is associated with Swiss cheese VSDs. (A) VSD viewed from right ventricle. Surgeon’s initial impression would be that patient had a single ventricle. (B) Same defect viewed from left ventricle. Malformation is clearly not a single ventricle. ALMV, Anterior leaflet of mitral valve; AV, aortic valve; PV, pulmonary valve; TV, tricuspid valve.

In rare instances, tricuspid valve chordae may straddle the ventricular septum in association with a large inlet septal defect resembling an inlet septal–type VSD but extending to the crux cordis ( Fig. 33.16 ). The tricuspid valve usually overrides both ventricles. When overriding is severe, the tricuspid anulus is usually very large, and many chordae from it are attached to the LV side of the septum (a combination of straddling and overriding). The atrial septum is malaligned relative to the ventricular septum. The right ventricle is often hypoplastic. The tricuspid valve may be regurgitant. This situation is covered in detail in Section III.

Inlet septal type of ventricular septal defect (VSD) with posterior extension and straddling tricuspid valve. (A) VSD viewed from right atrium. Crest of ventricular septum forming lower boundary of defect (black arrow) crosses almost beneath center of large tricuspid orifice, indicating severe malalignment of atrial and ventricular septa. (B) Same defect viewed from left ventricle. Chordal attachments of tricuspid valve cross VSD to attach to septal surface of left ventricle. This heart also exhibits transposition of the great arteries, with pulmonary trunk above left ventricle. LV, Left ventricle; MV, mitral valve; PV, pulmonary valve; RA, right atrium; RV, right ventricle; TV, tricuspid valve orifice.

Nearly half of patients undergoing surgical treatment for a primary VSD have an associated cardiac anomaly. ^, A moderate-sized or large patent ductus arteriosus (PDA) is present in about 6% of patients of all ages, but in about 25% of infants with heart failure. VSD occurs in combination with moderate or severe coarctation of the aorta in about 5% of patients. This combination is also much more common among infants with large VSD coming to operation younger than age 3 months.

Congenital aortic stenosis occurs in about 2% of patients requiring operation for VSD. Subvalvar stenosis is more common than valvar and may also occur in association with infundibular pulmonary stenosis. Subvalvar stenosis can be due to (1) a discrete fibromuscular bar lying inferior (caudad or upstream) to the VSD; (2) a discrete fibromuscular bar located distal (downstream) to the VSD, often consisting of displacement of infundibular septal muscle into the LV outflow tract (posterior malalignment), and often associated with aortic coarctation and interrupted arch ^{, ,} (see Chapter 40 ); (3) PAB ; and (4) excrescences of AV valvar tissue.

Congenital mitral valve disease occurs in about 2% of patients. One of the pulmonary arteries may be absent or severely stenotic. Severe peripheral pulmonary artery stenoses occur rarely.

Although atrial septal defects in general are not considered major associated anomalies, they may coexist with a large VSD in small infants and may be important lesions.

Severe positional cardiac anomalies (e.g., isolated dextrocardia, situs inversus totalis) are uncommon in patients with VSD.

The classic description of the pathology of hypertensive pulmonary vascular disease is that of Heath and Edwards ( Box 33.1 ).

Rp in patients with large VSD (and those with large PDA) is positively correlated with histologic severity of the hypertensive pulmonary vascular disease, classified by Heath and colleagues ( Fig. 33.17 ). A close positive correlation also exists between lowest Rp at rest or with isoproterenol infusion and Heath-Edwards grade of vascular disease. Heath-Edwards grades above 3 were not found in patients with Rp index less than 7 units · m ² , whereas those with Rp greater than 8.5 units · m ² showed changes characteristic of grade 4 or greater. Similarly, Fried and colleagues found a rather close negative correlation ( P =.001) between magnitude of left-to-right shunt and Heath-Edwards grade in infants and children coming to VSD repair. Variability in these matters is not unexpected because Heath-Edwards classification is based on the most severe lesion seen, regardless of its frequency. As noted by Wagenvoort and colleagues ^, and Yamaki and Tezuka, grading should include assessment of the number of vessels affected. In addition, calculation of Rp is open to errors.

Probability of hypertensive pulmonary vascular disease (HPDV) greater than grade 2 in patients with ventricular septal defect, given total pulmonary resistance index (units · m ² ). Dotted lines enclose 70% confidence limits ( P =.07).

(From Heath D, Helmholz HF Jr, Burchell HB, DuShane JW, Edwards JE. Graded pulmonary vascular changes and hemodynamic findings in cases of atrial and ventricular septal defect and patent ductus arteriosus. Circulation . 1958;18:1155.)

Hislop and colleagues provide a different view of hypertensive pulmonary vascular disease in infants with large VSD. Other investigators had noted earlier that intimal proliferation (and thus Heath-Edwards changes of grade 2 or greater) rarely develops in patients with large VSD until 1 or 2 years of age, ^, despite infants occasionally having severely elevated Rp. Hislop and colleagues found that infants dying at 3 to 6 months of age with large VSD and high (>8 units · m ² ) Rp with intermittent right-to-left shunting have marked medial hypertrophy affecting both large and small pulmonary arteries, including those less than 200 μm in diameter. The usual number of intraacinar vessels was present. By contrast, these investigators found that infants 3 to 10 months of age with large VSDs dying with a history of large Q ˙ p and heart failure and normal or slightly elevated Rp have medial hypertrophy affecting mainly arteries larger than 200 μm. The intraacinar vessels were fewer than usual, so-called lessened arterial density. These histologic features have been shown by Rabinovitch and colleagues to correlate with pulmonary hemodynamic findings after repair of VSDs. Fried and colleagues have emphasized that Heath-Edwards grade and arterial density are the best correlates of fall in pulmonary artery pressure after repair.

Histologic reversibility of pulmonary vascular disease after closure of VSD has not been documented. Favorable results in infants may be from an increase in arterial density as growth proceeds. Presumably, pulmonary vascular disease of Heath-Edwards grade 3 or greater severity is not reversible.

A significant number of congenital heart defects are diagnosed in utero with fetal echocardiography performed during the second trimester. Although complex lesions, such as hypoplastic left heart syndrome, are more easily detected, a significant number of isolated septal defects are also diagnosed in utero. Detection of perimembranous VSDs were noted to have superior sensitivity to muscular VSDs in a multicenter prospective cohort study conducted in 2017 by Chu and colleagues. Although these patients will not require neonatal intervention, prenatal diagnosis is helpful for parental counseling and establishment of postnatal care.

In infants, signs and symptoms of heart failure include tachypnea and liver enlargement, often associated with poor feeding and growth failure, and physical findings of a precordial pansystolic or more abbreviated systolic murmur and a hyperactive heart. These findings suggest the diagnosis of a large VSD. An apical diastolic murmur suggests large flow across the mitral valve during diastole, the result of a large Q ˙ p . Cardiomegaly and evidence of large Q ˙ p are seen on the chest radiograph. The electrocardiogram (ECG) usually shows biventricular hypertrophy. In older patients with large VSD, the history is often nonspecific, but examination also shows evidence of left ventricle and right ventricle enlargement and a systolic murmur usually best heard in the third and fourth left interspaces. In patients with doubly committed subarterial VSDs, the systolic murmur is maximal in the second and third interspaces, and in defects shunting mainly into the right atrium, in the fourth and fifth interspaces.

A high Rp from severe pulmonary vascular disease changes the hemodynamic state and clinical findings in patients with large VSDs. A large left-to-right shunt is no longer present because output resistances of the two pathways for LV emptying are similar, and the shunt is bidirectional and of about equal magnitude in both directions. The heart is not enlarged or hyperactive. A systolic murmur (produced by the large flow across the VSD) is soft or absent, and no apical diastolic murmur is heard. The pulmonary component of the second sound at the base is loud and sometimes palpable. Chest radiography may show cardiomegaly, an enlarged left atrium, a prominent pulmonary artery silhouette and increased pulmonary vascular markings. ECG shows severe RV hypertrophy rather than combined ventricular hypertrophy, and evidence of LV volume overload. When pulmonary vascular disease is even more advanced, cyanosis develops (Eisenmenger complex) because the shunt across the VSD becomes right to left as RV output resistance through the pulmonary vascular bed becomes higher than that through the VSD and aorta.

Patients with small VSDs have small shunts and often no abnormal signs or symptoms other than a pansystolic murmur. Chest radiography and ECG both may be normal. When the defect is moderate in size, the left ventricle is mildly or moderately enlarged (shown by physical examination, chest radiography, and ECG), and the volume of the right ventricle is increased.

When there is associated pulmonary or aortic stenosis, diagnostic features are changed. Thus, with important pulmonary stenosis, Q ˙ p is reduced, and the shunt may even be right to left. RV hypertrophy is increased. With important aortic stenosis, the load on the left ventricle is increased, and if the obstruction is cephalad to the VSD, left-to-right shunt is also greater, resulting in more than the expected degree of LV hypertrophy on ECG. Coarctation of the aorta may also produce these features in older children.

Two-dimensional echocardiography imaging of the VSD with color Doppler flow evaluation of shunt flow by proximal isovelocity surface area (PISA) has changed traditional views about preoperative studies. Thus, cardiac catheterization and cineangiography are not necessary before closure of primary VSDs when (1) the clinical syndrome in neonates and infants indicates a large Q ˙ p/ Q ˙ s ; (2) noninvasive imaging clearly defines the morphology, including that of the PA, aortic arch and ductus arteriosus; and (3) the surgeon is experienced in surgical identification and repair of congenital heart disease.

For identifying a large single perimembranous VSD, combined 2D echocardiography and Doppler flow interrogation is highly reliable in combination with clinical criteria ^, ( Fig. 33.2 ). Echocardiography adds to anatomic clarification, particularly in the case of doubly committed subarterial VSDs. Particularly for small VSDs and multiple muscular defects, 2D Doppler color flow echocardiographic imaging increases the sensitivity of echocardiography ( Fig. 33.2 A and B). However, and particularly in the presence of a single large VSD, multiple muscular defects can go undetected even with refined techniques of echocardiography. Because perimembranous VSDs are infrequently (<3% ) accompanied by additional muscular VSDs, this does not contraindicate proceeding to repair in infants without cardiac catheterization. Malalignment VSD is diagnosed by 2D echocardiography by the appearance of the alignment of the RV trabecular septum with the outlet septum. Malalignment may be anterior as in tetralogy of Fallot ( Fig. 33.2 C), posterior as in interrupted aortic arch, or rotational as in Taussig-Bing heart.

Size of a VSD is generally categorized echocardiographically as small, moderate, or large for purposes of decisions regarding surgery (see “ Morphology ” and “Indications for Operation” later in this chapter). A large defect has a diameter of 75% or greater of the aortic anulus and low-velocity flow by Doppler, measuring no more than 1 m · s ⁻¹ . A moderate defect has a diameter of 33% to 75% of the aortic anulus and flow velocity of 1 to 4 m · s ⁻¹ , indicating moderate flow restriction. (By the modified Bernoulli equation, gradient across the defect is calculated by multiplying velocity squared times 4). A small defect has a diameter less than 33% of the aortic anulus and a flow velocity of 4 m · s ⁻¹ or greater. When considering Rp, it is important to note that as resistance (or obstructions in the RV outflow tract) increases, flow velocity across the VSD decreases.

There now exist multiple methods to obtain more detailed information useful in preoperative planning for repair of VSDs. Three dimensional echocardiography has been used to define complex VSDs, particularly muscular ones especially in the presence of the Swiss cheese defects . Together with the increasing use of novel techniques such as 3D printing and virtual reality, the most challenging of VSDs are more easily identified and repaired ( Fig. 33.18 ). Computed tomography has advanced so that images can be compiled into reconstructions allowing for detailed imaging. Magnetic resonance imaging (MRI) has shown promise to provide accurate information about the morphology of all types of VSDs. All the above reconstructions may refine our ability to image and portray VSDs spacially.

Large anterior muscular ventricular septal defect (VSD) as seen by means of transthoracic echocardiography in (A) parasternal short-axis view and (B) subcostal left anterior oblique view, and by means of angiography: (C) anteroposterior-cranial and lateral projections of a retrograde injection into the left ventricle (LV) demonstrating a conoventricular and small muscular VSD, and (D) anteroposterior–right anterior oblique and left anterior oblique projections of a retrograde injection in the LV demonstrating the large anterior and small midmuscular VSDs.

When surgical intervention is under consideration in older children, cardiac catheterization and angiography are generally indicated to assess Rp and precisely identify location, size, and number of VSDs and any associated anomalies. Furthermore, preoperative sizing of VSDs is often important in arriving at management decisions. Sizing can be especially difficult when the VSD is associated with another lesion such as coarctation or pulmonary stenosis. The most reliable way to size the defect is to measure its diameter either by 2D color flow Doppler echocardiography or cineangiography. With cineangiography, the VSD must be accurately profiled and the measurement either corrected to allow for magnification or compared with aortic root diameter. In applying this method to perimembranous VSDs, the defect is smaller in a cranially tilted left anterior oblique (LAO) projection than in the conventional LAO position.

Cardiac catheterization should include both right-sided and left-sided heart studies, the latter mainly to obtain LV angiograms. Basic data obtained at cardiac catheterization should include oxygen consumption ( 1 2 ); systolic, diastolic, and mean pulmonary arterial, pulmonary artery wedge, and systemic arterial pressures; oxygen content and saturation in right atrial, pulmonary arterial, aortic, or peripheral arterial blood and, when possible, left atrial blood. Pulmonary ( Q ˙ p ) and systemic ( Q ˙ s ) blood flows and Q ˙ p/ Q ˙ s are calculated ² with Rp ( Table 33.3 ). When left atrial (or pulmonary arterial wedge) pressure is not available, only total pulmonary resistance (TPR) ³ can be calculated. Rp in absolute units × body surface area is of more value in predicting operability than is the ratio of resistances in pulmonary and systemic circuits. When Rp is elevated, further information concerning operability should be obtained by assessing response to exercise and to isoproterenol (see “ Indications for Operation ” later in this chapter).

Angiographic assessment of VSD is best performed using biplane techniques in appropriate projections. ^, Although cardiologists and radiologists carry primary responsibility for these studies, appreciation of their findings and limitations is essential to the surgeon, who must also understand when the study is incomplete.

Fig. 33.19 summarizes the surgically important features of angiograms of VSD by diagram. Fig. 33.20 presents representative angiograms of the various types of VSDs.

Line drawings of angiographic projections for assessment of ventricular septal defect (VSD) . (A) Interrelationships of left ventricle (LV) and aortic root (thick line) with right ventricle (RV) and pulmonary trunk (thin line) in 40-degree right anterior oblique (RAO) , 50-degree left anterior oblique (LAO) , and 40-degree cranially tilted (CR. LAO) projections. RAO view profiles infundibular (conal) and high anterior portions of RV outlet septum below and in front of right coronary sinus and profiles atrioventricular (AV) septum beneath noncoronary sinus of aortic root. Both LAO views profile apical trabecular portion of septum. LAO view also partly profiles RV outlet septum but superimposes it on LV outflow tract and aortic root. CR. LAO projection views RV outlet septum en face and superimposes it on LV. Because orientation shows a horizontally lying heart, LAO view depicts full length (cranial to caudal) of apical and anterior trabecular portion of ventricular septum and AV valve obscured (interrupted lines) , whereas CR. LAO view depicts full length of sinus portion of trabecular septum from base to apex. (B) Both cranially tilted (CR. LAO) and conventional LAO views are required for a complete assessment of sinus septum. Basal (inlet) (O, x) VSDs are separated from more apical (o) VSDs by CR. LAO projection, whereas high (x) VSDs are separated from low (O) VSDs by LAO view. (C) Anatomic and hemodynamic features of VSDs shown by LV angiograms. LAO diagrams show a compromise between conventional and cranially tilted options. LV and aorta are shown by thick lines, RV and pulmonary trunk by thin lines, and AV valves and nonprofiled VSDs by interrupted lines. (C1) Perimembranous VSD. LAO view profiles VSD just beneath parietal band (ventriculoinfundibular fold) at upper margin of inlet septum. Flow enters base of RV above tricuspid valve, filling base before reaching infundibulum. Tricuspid valve is well seen in diastole, and lower margin of defect can be accurately related to tricuspid anulus in LAO. RAO view does not profile defect unless it extends into outlet septum. Note intact AV septum beneath noncoronary sinus of aortic root. Shunt enters RV infundibulum, crossing but not interrupting intact superior margin of LV, indicating intact conal and high anterior septal regions. (C2) Doubly committed subarterial VSD (labeled conal septal VSD ). LAO view shows an intact septum from aortic valve to apex. RV sinus usually fills only faintly by diastolic mixing from infundibular region, and tricuspid valve may not be seen. Defect is superimposed on aortic root. RAO view profiles defect beneath contiguous parts of aortic and pulmonary valves. Systolic streaming through RV infundibulum to pulmonary trunk is well shown, with some mixing to more anterior part of RV in diastole, but high anterior septal region is intact. (C3) Inlet septal VSD (labeled basal muscular VSD ). VSD is adjacent to tricuspid valve (AV septal type) or separated from it by a rim of muscle (muscular VSD). These two types of VSDs are not readily distinguished radiologically. In LAO view, defect is profiled between AV valves, replacing full height of basal septum (conventional LAO view), perhaps extending into adjacent middle portion of ventricular septum but not into apical region (cranially tilted LAO view). Contrast medium streams directly into base of RV sinus in systole, providing a good depiction of tricuspid orifice in diastole. Separate AV valves are present, in contrast to the finding in a complete AV septal defect (see Chapter 34 ). In RAO view, VSD is not profiled. Intact AV septum distinguishes this defect from a true AV septal defect. Note intact conal and high anterior septal regions. (C4) Muscular, trabecular VSD (labeled mid-muscular VSD ). LAO views show an intact inlet septum and no extension into apical region, although a small additional defect is seen in diastole, closing in systole. Some of the contrast medium streams directly into RV outflow during systole. Height of defect from floor of ventricle (bottom of AV valve) is appreciated in LAO view, and separation from basal and apical regions in cranially tilted LAO view. RAO features are as in parts (C1) and (C3). (C5) Multiple muscular anterior and apical VSDs. Muscular VSDs in these regions frequently coexist and, if numerous, form a continuous series throughout trabeculated septum from high in RV infundibulum to apical sinus septum. For clarity, only highest and lowest are shown here. In LAO view, intact basal and middle septal regions are profiled. Apical defects are profiled, but high anterior defects are superimposed on LV outflow region. Contrast medium tends to stream to RV outflow tract without filling basal parts. In RAO view, high anterior defects are profiled, interrupting superior margin of LV anterior to intact outlet septum. More defects are open in diastole than in systole. CR. LAO, Cranial left anterior oblique; L, left coronary; LAO, left anterior oblique; LV, left ventricle; N, noncoronary; R, right coronary; RAO, right anterior oblique; RV, right ventricle.

(From Brandt. )

Angiograms of patients with ventricular septal defect (VSD). (A) Left ventricular (LV) angiograms of a perimembranous VSD. (A1) 40-degree cranially tilted 60-degree left anterior oblique (LAO) projection, systolic frame, early in perimembranous angiographic sequence. VSD (arrow) lies in basal part of ventricular septum adjacent to aortic root. No additional defects are seen in middle and apical portions of septum (catheter to LV through atrial septum and mitral valve). (A2) 30-degree right anterior oblique (RAO) projection, systolic frame, slightly later than (A1) in sequence. Patient was positioned to achieve cranial tilting of simultaneously exposed LAO view shown in (A1). Note intact atrioventricular septum beneath noncoronary aortic sinus and intact outlet septum (C). Contrast medium from shunt through nonprofiled VSD fills right ventricular (RV) outflow tract, crossing (arrow) but not interrupting high anterior margin of LV. (A3) 50-degree LAO projection, systolic frame early in sequence (second injection). Perimembranous VSD is profiled as in (A1) beneath aortic root. Large arrow indicates flow into base of RV above tricuspid valve (identified in diastole but not illustrated). Downward extent of VSD (small arrow) is accurately shown, and there are no additional defects lower in septum. Perimembranous defects are frequently small, of dimensions profiled in cranially tilted LAO projection in (A1), compared with LAO. (B) LV angiograms of doubly committed subarterial VSD. (B1) 60-degree LAO projection, systolic frame early in sequence. Pulmonary arteries are filled by shunt through RV outlet defect superimposed on LV outflow tract. Only slight contrast medium is seen in RV sinus, and whole of sinus septum is shown to be intact. (B2) 30-degree RAO projection, diastolic or very early systolic frame early in sequence. Doubly committed subarterial VSD is profiled immediately beneath contiguous parts of aortic and pulmonary valves, still closed. Arrows show streaming from VSD toward pulmonary valve, with some filling of remainder of RV infundibulum, but high anterior LV margin is intact. (C) LV angiocardiograms of muscular VSDs. (C1) Muscular anterior VSD. 30-degree RAO projection, diastolic or very early systolic frame early in sequence. Shunt through large, high-anterior muscular VSD fills anterior part of RV infundibulum. Arrows show the main stream toward pulmonary valve, which is still closed. There is a little mixing in RV sinus, but outlet septum is intact. (C2) Multiple muscular VSDs (Swiss cheese septum); 40-degree cranially tilted 60-degree LAO projection, systolic cine frame. Large muscular trabecular VSD (large arrow) , accompanied by numerous small muscular apical defects (small arrows) , is profiled, but basal part of ventricular septum beneath aortic root is intact. In diastole (not shown), more numerous apical defects were apparent. (C3) 30-degree RAO projection, diastolic frame in same patient as in (C2). Numerous muscular anterior VSDs (arrows) interrupt LV margin. Note intact outlet septal margin of LV near aortic valve. Earlier in sequence, intact atrioventricular septum was identified, but base of filled RV overlaps base of LV in this frame. Note that position of large muscular VSD is incompletely evaluated (trabecular); an LAO view would be necessary. Note surgically banded pulmonary trunk. A, Aortic valve; Ao, Aorta; C, septum; D, subarterial ventricular septal defect; P, pulmonary valve; PT, pulmonary trunk; R, right ventricle; V, atrioventricular septum.

Some VSDs tend to close spontaneously. This is relevant to decisions about operation and explains, for the most part, the infrequency with which large VSDs are encountered in adults. An inverse relation exists between the probability of eventual spontaneous closure and age at which the patient is observed ^{, , ,} ( Fig. 33.21 ). About 80% of patients with VSDs seen at age 1 month experience eventual spontaneous closure, as do about 60% of those seen at age 3 months, about 50% of those seen at age 6 months, and about 25% of those seen at age 12 months. This decreasing tendency for spontaneous closure of a VSD as the patient grows older has also been confirmed by Beerman and colleagues, and spontaneous closure has been documented to occur in only one patient between age 21 and 31 years. Onat and colleagues studied 106 children with VSD and concluded that these patients should be followed closely through adolescence because the defects may decrease in diameter, shunt flow may diminish, and spontaneous closure may be expected in 23% of patients.

Probability of eventual spontaneous closure of a large ventricular septal defect (VSD) according to age at which patient is observed. Dotted lines enclose 70% confidence limits. Specific ratios, with 70% confidence limits, reported by Hoffman and Rudolph and Keith and colleagues are shown centered on mean or assumed ages of patients in their reports. P for age <.0001. See original sources for equations and statistics.

(From Blackstone EH, Kirklin JW, Bradley EL, DuShane JW, Appelbaum A. Optimal age and results in repair of large ventricular septal defects. J Thorac Cardiovasc Surg . 1976;72:661.)

The mechanism of narrowing or closure of perimembranous VSDs is usually adherence of tricuspid leaflet or chordal tissue to the edges of the VSD. ^, Closure has erroneously been related to echocardiographic diagnosis of aneurysm of the membranous septum. Aneurysm of the membranous septum is usually considered benign and functionally reduces the size of the VSD. It has the potential consequence of promoting tricuspid regurgitation and RV outflow tract obstruction and is a nidus for infective endocarditis.

Perimembranous VSDs, as well as VSDs that are juxtaaortic and inlet VSDs of the AV septal type, are less likely to close than juxtatricuspid or subarterial muscular VSDs. The rare perimembranous VSD with LV-to–right atrial shunt (Gerbode defect) in infancy is also associated with less chance of spontaneous closure.

Inferences about the tendency toward spontaneous closure seem to be in disagreement with the results of some studies. Hoffman and Rudolph’s data (one of the sources for Fig. 33.21 ) indicate that 80% of infants aged 6 weeks with large VSDs will experience spontaneous closure or reduction in size of the VSD. Rowe found that none of 11 infants (mean age 46 days) with a VSD 80% or greater in diameter than that of the aorta showed subsequent reduction in size during the period of observation. These apparent discrepancies may be explained by lack of information about location or size of VSDs.

A large VSD is less likely to close spontaneously and exposes the patient to risk of developing increased Rp from hypertensive pulmonary vascular disease ( Table 33.3 ), which tends to worsen with age. ^, Thus, the proportion of patients with large VSDs who have severely elevated Rp is directly related to age ( Fig. 33.22 ). The statement that some infants younger than 2 years of age with large VSDs have severely elevated Rp is doubted by some, but its occurrence is well documented.

Estimated (not calculated) probability of developing severe pulmonary vascular disease (pulmonary vascular resistance 8 units · m ² or greater) in patients with large ventricular septal defects, according to age.

(From Keith and colleagues. )

Some infants and children with severely elevated Rp have not undergone the usual fall in Rp a few weeks to a few months after birth. Others have undergone this decrease, but later in the first 2 years of life, they have developed a rapid increase in Rp.

Some infants with large VSDs and most of those with moderate-sized VSDs have normal or mildly elevated Rp and retain this through the first decade of life. Then, if their VSD is still large, more severe pulmonary vascular changes may or may not develop as they age. In infants with small VSDs, pulmonary vascular disease does not develop.

Infective endocarditis is rare in patients with VSD, occurring at a rate of about 0.15% to 0.3% per year. ^, Its prevalence is greater in males and individuals older than 20 years of age. Infective endocarditis is more common in small and moderate VSDs than in large VSDs. Often a pulmonary process is the presenting feature, presumably developing from emboli secondary to right-sided bacterial vegetations or bacteria carried to the lungs by left-to-right–directed flow through the VSD. Prognosis with modern antibiotic treatment regimens is good. Currently, the American Heart Association does not recommend dental prophylaxis for infective endocarditis in patients with an unrepaired VSD.

Past experience and reports in the literature indicate that without surgical treatment, about 9% of infants with large VSDs die from them in the first year of life. Death may result from heart failure, which may develop very early but usually occurs at about age 2 to 3 months, presumably because at that time the left-to-right shunt increases as the medial hypertrophy present in the small pulmonary arteries at birth regresses. Death may also result from recurrent pulmonary infections, often viral in origin, secondary to pulmonary edema from high pulmonary venous pressure. Death is most likely to occur in those infants with large VSDs who have associated conditions of major anatomic or functional importance, such as PDA, coarctation of the aorta, or large atrial septal defect.

After the age of 1 year, few if any patients die of their VSD until the second decade of life. By then, many patients whose VSDs have remained large have pulmonary vascular disease and ultimately die with complications of Eisenmenger complex ( Fig. 33.23 ). These include hemoptysis, polycythemia, cerebral abscess or infarction, and right-sided heart failure.

Survival after diagnosis of patients with large ventricular septal defects who had proven elevation of pulmonary vascular resistance to a level that made them inoperable (10 units · m ² or greater), as demonstrated at cardiac catheterization at various ages. Note that fatalities begin to occur in the second decade of life, about half the patients were dead by age 35, and a few survived until 50 years of age.

(Modified from Clarkson PM, Frye RL, DuShane JW, Burchell HB, Wood EH, Weidman WH. Prognosis for patients with ventricular septal defect and severe pulmonary vascular obstructive disease. Circulation . 1968;38:129.)

Patients with small VSDs die very rarely as a result of bacterial endocarditis. However, in common with patients with larger VSDs, some of these patients may develop disturbed systolic function and increased compliance in both ventricles.

Patients with small VSDs rarely have symptoms related to the defect. Those with large VSDs may have symptoms of heart failure in the first few months of life, with poor peripheral pulses, inability to feed, sweating, and chronic pulmonary edema. Most infants with a large VSD have severe failure to thrive and are referred for surgical closure. During early life, rapid and labored respiration and recurrent pulmonary infections may occur secondary to high pulmonary venous pressure and chronic pulmonary edema. Lobes of the lung may become chronically hyperinflated because of pressure of the large and tense pulmonary arteries on the bronchi, preventing complete escape of air during expiration. All this causes many babies with large VSDs to be small and physically underdeveloped. Symptomatic patients who fail to respond well to medical management are at particular risk of dying in the first year of life. Some babies who survive through the first year of life with large VSDs have controlled heart failure and failure to thrive in the second year of life as well.

Children and young adults with large VSDs are usually symptomatic and tend to be small in both height and weight. As pulmonary vascular disease develops, symptoms may regress.

See Section II: Ventricular Septal Defect and Aortic Regurgitation .

A small proportion (5%–10%) of patients with large perimembranous VSDs and large left-to-right shunt in infancy develop infundibular pulmonary stenosis resulting in a double chambered right ventricle. ^, The mild and moderate infundibular pulmonary stenoses in patients operated on for primary VSD, as well as some of the more important pulmonary stenoses, probably develop in this way. Severe double chambered right ventricle may be associated with shunt reversal and cyanosis. Unlike tetralogy of Fallot in which there is a large unobstructed anterior malalignment VSD, patients with double-chambered right ventricle have a smaller perimembranous VSD, which may lead to severe RV hypertrophy and a noncompliant right ventricle.

After CPB has been established, the aorta is occluded, cold cardioplegic solution injected, and the right atrium opened obliquely. A suction device is placed across the naturally present or surgically created foramen ovale ( Fig. 33.24 ). Before repair is started, the defect is carefully examined to establish that all margins can be seen and reached. In rare circumstances in which this is not possible because of chordal arrangement, an incision is made to disconnect a portion of the tricuspid valve from the anulus, and the VSD is exposed through the resulting aperture. Particular attention is directed toward determining whether the VSD is juxtatricuspid, in which case it abuts the tricuspid valve in the region of the commissure between septal and anterior leaflets. If the VSD has a bar of muscle of varying width between it and the tricuspid valve, it is not juxtatricuspid. Relationship of the bundle of His to the posterior and inferior margins of the defect must be clearly understood (see “ Morphology ” earlier in this section) to accomplish a safe repair ( Fig. 33.24 A).

Repair of perimembranous ventricular septal defect (VSD) from right atrium, continuous suture technique. (A) Right atriotomy is parallel to atrioventricular groove from right atrial appendage toward inferior vena cava. Stay sutures are placed to expose tricuspid orifice. Superior edge of VSD is not visible because of overlying anterior leaflet of tricuspid valve. Atrioventricular node lies within triangle of Koch, with bundle of His penetrating to ventricular septum at posterior angle of VSD, where it is particularly vulnerable to injury. (B) Repair of VSD is started at junction of septal with anterior leaflets of tricuspid valve. A pledget-reinforced 4-0 polypropylene suture is placed as a mattress stitch through tricuspid anulus, with pledget on atrial side of tricuspid valve. Suture is passed through a knitted double-velour polyester patch trimmed to slightly larger than size of VSD. Alternative patch material could be pericardium or polytetrafluoroethylene. (C) Continuous stitches are placed along right side of superior rim of defect to approximate patch to ventricular septum. Simultaneous traction on suture and on patch exposes next area to be stitched and provides good visibility. Aortic valve is located to left side of septum in this area (ventriculoinfundibular fold) and must be protected from inclusion of cusp tissue in suture line. Opposite end of suture is then passed through septal leaflet of tricuspid valve as a continuous mattress stitch working inferiorly. Bundle of His crosses beneath this portion of suture line. Stitches must not penetrate tricuspid anulus or into atrial myocardium, to preserve integrity of conduction system. (D) At a point 5 to 7 mm below inferior margin of VSD, suture line is transitioned from septal leaflet onto ventricular septum. Stitching continues along inferior rim of VSD, with stitches placed 5 to 7 mm below rim until reaching muscle of Lancisi. An alternative technique uses interrupted pledgeted mattress sutures for very thin portions of the septal leaflet and posteroinferior edge of defect (conduction system) to facilitate secure suture placement while avoiding conduction system. Remainder of suture line employs a continuous suture technique. (E) Suture line may come to edge of VSD anterior to muscle of Lancisi and is continued until meeting previously completed superior suture line. Suture ends are joined to complete repair. Alternatively, repair may begin at point described here as end point. Initial suture line proceeds along superior edge of defect to junction of anterior and septal leaflet of tricuspid valve. Second part of suture line is carried along septum inferiorly, 5 to 7 mm below edge of defect, transitions to septal leaflet, then proceeds as a continuous mattress stitch along septal leaflet superiorly to join other end of suture to complete repair. Ao, Aorta; IVC, inferior vena cava; SVC, superior vena cava.

In older infants and children, the VSD is repaired with a polyester patch sewn in place with continuous polypropylene sutures ( Fig. 33.24 B-E), a technique confirmed to be entirely adequate in such patients. In neonates and small infants, the technique may not be adequate because of the delicate nature and friability of the structures. In these patients, the patch may be sewn into place using a combination of continuous and interrupted pledgeted mattress sutures or, alternatively, employing exclusively interrupted mattress sutures reinforced with small pledgets.

A ventricular approach may be used when the VSD cannot be well visualized from the right atrium. An RV approach is performed through a transverse incision. The patch is sewn into place with continuous or interrupted sutures ( Fig. 33.25 ). Techniques of repair and sequence for suturing shown in Fig. 33.25 are slightly different from those shown for the atrial approach. Suturing begins at the transition point between the septal leaflet of the tricuspid valve and the ventricular septum, 5 to 7 mm below the edge of the septal defect. This critical point is given attention by all experienced surgeons.

Repair of perimembranous ventricular septal defect (VSD) from right ventricle (RV) , interrupted suture technique. (A) Transverse ventriculotomy is made low in outflow tract. A right atriotomy has been made previously to examine atrial septum for defect, with a vent device placed across patent or surgically made foramen ovale, which will be closed later. (B) Retraction stitches are placed through myocardium superiorly and inferiorly to expose interior of RV. VSD is partialbscurecured by anterior leaflet of tricuspid valve, which must be retracted to expose septal leaflet. (C) Septal leaflet of tricuspid valve is retracted to expose junction of tricuspid anulus with ventricular septum. A pledget-reinforced mattress stitch of 4-0 polypropylene suture is placed to create a transition from septal leaflet to ventricular septum. One arm of suture is placed entirely on septal leaflet, and other arm is placed into ventricular septum at hinge point of septal leaflet on ventricular septum. Stitch is at least 5 to 7 mm below rim of VSD. Suture is passed through a knitted double-velour polyester patch fashioned to be somewhat larger than VSD. Alternative patch material could be pericardium or polytetrafluoroethylene. (D) Several pledget-reinforced mattress stitches are placed around perimeter of VSD. Stitches are placed entirely in septal leaflet tissue between transition stitch and junction of septal and anterior leaflets of tricuspid valve. Stitches are placed 5 to 7 mm below rim of defect between transition stitch and papillary muscle of Lancisi, which demarcates anterior extent of specialized conduction system. Rest of stitches may be placed in rim of septal defect. All stitches are placed through ventricular septum and septal leaflet of tricuspid valve before approximating patch to ventricular septum. (E) Patch is attached securely to ventricular septum by tying all sutures. Ao, Aorta; PT, pulmonary trunk; RA, right atrium.

Usual de-airing procedures are performed, and the remainder of the operation is completed as usual.

Transverse incision in the RV infundibulum is the classic approach for repair of doubly committed subarterial VSDs ( Fig. 33.26 ). However, many surgeons expose this type of subarterial VSD through a transverse incision in the main pulmonary artery and retraction of the pulmonary valve. These defects should always be closed with a patch to reduce the possibility of distorting the semilunar valves. The patch must be carefully shaped to avoid distortion of the aortic or pulmonic valve leaflets. A continuous stitch technique is employed. When pledgeted sutures are used, they are placed from just above the pulmonary valve leaflets, and pledgets come to lie in the pulmonary valve sinuses. Care is taken not to damage the left main coronary artery.

Repair of doubly committed subarterial ventricular septal defect (VSD) . (A) Transverse incision is made in outflow tract of right ventricle (RV) near ventriculopulmonary arterial junction. VSD could also be approached via pulmonary trunk (PT) . (B) VSD is subarterial, meaning that it is directly below valves of both great arteries. Superior border of VSD is pulmonary and aortic valves, and both valves are committed equally to defect. (C) Initial stitches of 4-0 or 5-0 polypropylene suture are placed through narrow fibrous rim separating pulmonary valve anteriorly from aortic valve posteriorly. Stitches are passed through a patch (knitted double-velour polyester, polytetrafluoroethylene, or pericardium) that is slightly larger than VSD. Each stitch in this area must be placed with aortic valve in view to avoid damaging its cusps. Cardioplegic solution may be infused into aortic root for better visualization of aortic valve while placing stitches in this area. (D) Remainder of defect is closed by placing stitches through rim of VSD and through patch. Bundle of His is located far posterior and is unrelated to posterior rim of VSD. Ao, Aorta; RA, right atrium.

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