The prevalences and precise nature of the various types of morphology of severely stenotic aortic valves and coexisting anomalies are incompletely understood for several reasons. First, it is difficult to obtain enough cases to constitute a reasonable sample of the spectrum of severe congenital valvar stenosis in neonates, infants, and children. Second, sources of data range from autopsy studies and surgical studies to echocardiographic and cineangiographic imaging in patients undergoing balloon valvotomy. Third, differing terminology contributes to incompleteness of morphologic data; ideally, not only should the morphologic nature of the cusps be defined but also that of the sinuses of Valsalva, commissures (upper points of attachment of cusps to the aortic wall), and interleaflet triangles (fibrous or muscular tissue interposed between the sinuses in the subcusp left ventricular outflow tract), as described by Angelini and colleagues for bicuspid valves.

In patients with stenosis severe enough to require operation in infancy or childhood, the valve is bicuspid in about 65% ( Table 50.1 ). The valve usually consists of thickened right and left cusps in association with anterior and posterior commissures and a slit-like orifice with its long axis in the sagittal plane ( Fig. 50.1 A). The left cusp is frequently the larger and may contain a transversely placed central thickened ridge, or buttress, representing a rudimentary commissure between normal right and left cusps. Less often, the two cusps are anterior and posterior, and the orifice is then oriented in a coronal plane. There is usually fusion peripherally of one commissure and occasionally of both. However, severe stenosis can occur without fusion, resulting only from thickened cusps with or without fibrous/myxomatous nodules and a bicuspid configuration. If free edges of both thickened cusps are taut, they are then equal in length to the diameter of the aortic root and cannot open ( Fig. 50.1 B). Most bicuspid valves will show three intercusp triangles on their ventricular side, indicating that three cusps were present in the developing valve. A bicuspid valve with only two definitive cusps is uncommon and usually is not stenotic early in life, rather presenting later in life with obstruction or regurgitation. A full discussion of the genetics, morphology, natural history, and therapeutic options for adult patients with a congenitally bicuspid aortic valve is found in Chapter 12 .

Specimens of congenital aortic stenosis with a bicuspid valve. (A) Bicuspid valve with mild cusp thickening, moderately redundant cusps, and fusion of one commissure. There is a diminutive buttress (commissure) in the anterior cusp (arrow). (B) Bicuspid valve from a neonate with severe aortic stenosis. Cusps are very thickened and obstructive, but there is no commissural fusion or buttress formation.

In about 30% of patients the valve is tricuspid, with three thickened cusps of approximately equal size and three recognizable commissures that are fused peripherally to varying degrees, creating a dome with a central stenotic orifice. This type of valve is more favorable for valvotomy because all three commissures can usually be opened.

Less often (5%), the valve may have a unicuspid configuration with only one commissure ( Fig. 50.2 ). This variety is more common in infants presenting with severe stenosis. Occasionally, however, the stenosis is not severe, and signs and symptoms develop in later life as the valve thickens and calcifies. A thickened unicuspid valve is inherently stenotic, whether the commissure is fused or not, unless the cusp is particularly redundant.

Specimen of a unicuspid aortic valve. Single fused commissure is suitable for valvotomy, but cusps cannot be divided elsewhere without producing regurgitation.

Rarely, the valve may be quadricuspid. Valve regurgitation is the most common functional abnormality, which usually does not progress. About half the reported cases have additional congenital heart defects.

The cusps are approximately equal in size in only a small percentage of congenitally bicuspid or stenotic tricuspid valves. Likewise, the raphae are variable in thickness and length. Number of sinuses may not be the same as number of cusps; most congenitally bicuspid and unicuspid (unicommissural) valves have three sinuses and three intercusp triangles. ^,

Diffuse cusp thickening, most marked at the free cusp edges, contributes importantly to valvar stenosis. Thickening is more extreme in symptomatic neonates and infants, and cusps may be irregular and myxomatous or dysplastic in appearance. In addition, particularly in infants, the aortic anulus may be hypoplastic, especially with unicuspid valves, and frequently in association with other components of hypoplastic left heart syndrome such as endocardial fibroelastosis (EFE) of a hypoplastic LV ( Fig. 50.3 ), coarctation of the aorta, patent ductus arteriosus, and mitral regurgitation or stenosis. ^,

Specimen from 10-day-old infant with severe aortic valvar stenosis. Opened left ventricle with thick walls and marked endocardial fibroelastosis is relatively hypoplastic compared with enlarged right ventricle. A small anterior mid-muscular ventricular septal defect is present. AOV, Aortic valve; LAA, left atrial appendage; LV, left ventricle; MV, mitral valve; RV, right ventricle; VSD, ventricular septal defect.

The LV is always concentrically hypertrophied in children with severe aortic stenosis, but in infants, hypertrophy may be extreme, with a tiny cavity and extensive fibrosis in the wall ( Fig. 50.4 ). Fibrosis is primarily in the subendocardial region. Extensive EFE may also be present, possibly the result of ischemia of subendocardial layers. In these hearts, the ventricle may be dilated ( Fig. 50.5 ).

Specimen of congenital aortic stenosis from 9-month-old infant. Aortic valve (AV) cusps are thickened, nodular, and myxomatous. Opened left ventricle (LV) is small and has extreme hypertrophy and moderate endocardial fibroelastosis that also involves the papillary muscles of the mitral valve (MV) .

Specimen of congenital aortic stenosis from 12-day-old infant. Opened left ventricle (LV) is hypertrophied and dilated. Smooth septal surface is due to endocardial fibroelastosis that measures 1.5 mm in thickness. There is associated congenital mitral valve (MV) disease, with thickened leaflets and chordae and obliteration of interchordal spaces (see “ Morphology ” in Chapter 49 ).

Congenital valvar aortic stenosis may be associated with a fibrous subvalvar or supravalvar stenosis, as well as with coarctation of the aorta and hypoplastic aortic arch.

The various coexisting components of hypoplastic left heart syndrome include left ventricular hypoplasia of varying degrees, extreme left ventricular hypertrophy with small cavity size, EFE, congenital mitral stenosis or regurgitation, severe coarctation, hypoplastic aortic arch, and subaortic stenosis caused by mitral valve abnormalities ( Table 50.2 ). Patent ductus arteriosus or ventricular septal defect (VSD) as well as pulmonary atresia may also be present. Occasionally there is associated dextrocardia.

Neonates and infants with severe valvar aortic stenosis usually present with pallor, perspiration, and inability to feed. Shortness of breath and cyanosis may be present. In children and young adults, even important stenosis may be without symptoms. However, effort dyspnea, effort angina, or effort syncope, singly or in combination, usually indicates a severe lesion. Dyspnea may be present with moderate stenosis.

In neonates and infants with severe valvar aortic stenosis, the most striking feature is small pulse volume with pallor, dyspnea, and at times cyanosis. Both the murmur and gradient across the valve may be unimpressive because of a low cardiac output. There also may be a hyperactive right ventricular (RV) impulse.

Clinical signs in children and young adults include an ejection systolic murmur (and thrill) at the base radiating to the carotid vessels, accompanied by a systolic ejection click. An aortic diastolic murmur is uncommon, particularly when compared with patients with discrete subvalvar stenosis. A severe lesion is characterized by palpable pulse of low volume and slow upstroke, single or reversed splitting of second heart sound, apical fourth and sometimes third heart sound, and thrusting left ventricular impulse.

Many investigators have concluded that physical signs are unreliable in assessing severity of valvar stenosis in children. ^, However, physical signs can be used to differentiate among mild, moderate, and severe lesions in most patients, and severe lesions can always be distinguished from mild ones.

The electrocardiogram (ECG) usually shows severe left ventricular hypertrophy but can be near normal. Right ventricular hypertrophy on the ECG may be associated with a left-to-right shunt at atrial level through a stretched patent foramen ovale and rarely a reversed shunt at ductus level.

The ascending aorta frequently is prominent in older children but is small in neonates and infants. Increased heart size is seldom seen except in neonates and infants in heart failure, in whom it may be marked. Radiologically demonstrable valvar calcification is rare in patients younger than age 25.

Two-dimensional echocardiography has become particularly important as a diagnostic tool. In neonates and infants, morphology and severity of narrowing of the valve and size, wall thickness, and contractility of the LV can be assessed. The congenitally stenotic aortic valve can be continuously reevaluated by Doppler ultrasound measurement of flow velocity across stenotic valves, which can be used to quantify transvalvar pressure gradient. Echocardiographic markers are useful for managing fetuses with important aortic stenosis. Serial measurements of fetal cardiac size and function may predict postnatal outcome.

Estimation of subendocardial oxygen requirements may be helpful in assessing severity of stenosis. ^,

A systolic gradient across the aortic valve can be demonstrated at cardiac catheterization, usually through a retrograde aortic approach if possible or otherwise a transseptal approach. Cardiac output can also be measured so that valve area can be calculated. Systolic gradient greater than 75 mmHg or valve area less than 0.5 cm ² · m ^–2 is indicative of severe stenosis. Measuring gradient and valve area at cardiac catheterization has become less important as echocardiographic measurements have become more accurate. A raised left ventricular end-diastolic pressure indicates left ventricular failure or a fibrotic and noncompliant ventricle.

Angiography demonstrates thickened leaflets that form a dome in systole, with a localized jet of contrast entering the aorta ( Fig. 50.6 ). Although this type of study is not reliable in assessing severity of stenosis, it can assess size of the aortic anulus and LV. An aortic root injection allows quantification of aortic regurgitation if present.

Angiographic signs of aortic stenosis. In valvar stenosis , there is systolic doming and a jet between thickened cusps. Poststenotic dilation of aorta is visible. In fibrous subvalvar stenosis , a jet may be seen and cusps may not open fully, but doming is absent. The membrane should be visible, and there is often mild aortic regurgitation. In supravalvar stenosis , narrowing commencing above aortic cusps is visible. Sinuses of Valsalva are prominent, and coronary arteries are often dilated.

By a combination of clinical and hemodynamic assessments (echocardiography, cardiac catheterization), patients with congenital valvar aortic stenosis can be categorized as having mild, moderate, or severe obstruction. Mild implies that pulse volume and contour are normal, as is the second heart sound. Patients with these findings have an LV-aortic systolic pressure difference less than 40 mmHg at rest, with a mean of 20 mmHg. Patients with moderate stenosis have an abnormally small pulse volume on palpation and abnormal contour, and narrow inspiratory splitting of the second heart sound may be present. Such patients generally have systolic gradients less than 75 mmHg, with a mean of 20 to 50 mmHg. Patients with severe stenosis have a systolic gradient in excess of 75 mmHg and an abnormal pulse volume and contour, as well as a single second heart sound or reverse splitting. These patients have a mean calculated aortic valve area index of less than 0.5 cm ² · m ^–2 .

When neonates and infants present with valvar stenosis, the lesion is typically severe, with rapidly progressive heart failure and death within a few days to a few weeks of birth. Thus, most neonates and young infants come to intervention (currently with percutaneous balloon valvotomy) critically ill. Many have other anomalies associated with the spectrum of the hypoplastic left heart syndrome. Ten Harkel and colleagues noted a 5-year survival rate of 73% among patients presenting in infancy.

When symptoms are delayed beyond age 1 year, heart failure is rare, and survival without treatment generally is prolonged. Also, associated anomalies are less common. The Second Natural History Study of Congenital Heart Defects includes data on many patients treated for valvar aortic stenosis and followed for 25 years. Patients were 2 years or older at entry into the study, and 40% managed medically subsequently required surgical management. For patients presenting with LV-aortic pressure gradient greater than 50 mmHg, 70% required surgical intervention. Almost 40% of patients required a second operation.

Survival is related to (1) sudden death in untreated children and (2) rate of progression of stenosis.

Progression of stenosis.

When congenital aortic valvar deformities are nonobstructive in infancy and childhood, less than 10% progress to mild obstruction within about 10 years. Leech, Mills, and colleagues obtained information on 26 patients aged 1 week to 29 years when first seen, and in whom diagnosis of nonobstructive aortic valve deformity was made based on an isolated aortic ejection sound. During a 5- to 16-year follow-up, two patients (7%; CL 2%–16%) developed signs of mild stenosis after 7 and 15 years. As more years pass, an undetermined time-related proportion of patients with deformed (usually congenitally bicuspid) aortic valves develop progressive thickening and calcification and ultimately important stenosis. Vollebergh and Becker suggest that minor inequality of size of tricuspid valves present from birth may lead to formation of senile or degenerative type of aortic valve stenosis presenting in the seventh or eighth decade of life.

When mild stenosis is present at first evaluation in childhood, progression is more rapid. Moderate or severe stenosis develops in about 20% of patients within 10 years and in 45% within about 20 years. Even after this long interval, therefore, 55% of the mild lesions remain mild.

When moderate stenosis is present initially, the lesion becomes severe within 10 years in about 60% of patients ( Fig. 50.7 ).

Cumulative incidence curves for 54 patients presenting with originally moderate congenital valvar aortic stenosis (AS). Vertical bars represent 70% confidence limits. Mean age at presentation was 12 years (1–25 years) and mean follow-up 8.5 years (1–24 years). The two deaths were both sudden, 4 and 9 years after presentation, in association with progression to severe stenosis. Percentages refer to distances between curves.

(From Hossack KF, Neutze JM, Lowe JB, Barratt-Boyes BG. Congenital valvar aortic stenosis: natural history and assessment for operation. Br Heart J . 1980;43:561.)

Percutaneous balloon valvotomy is often used for treating congenital valvar aortic stenosis, but a description of this technique is beyond the scope of this text. Its place in treating neonates is discussed later in this section.

Closed techniques and surface cooling for hypothermic circulatory arrest have largely been replaced by aortic valvotomy on CPB using cold cardioplegic myocardial management.

Anesthetic and supportive management must be precise. Drifting downward of body temperature to 32°C to 34°C is probably advantageous. As the pericardium is being opened, care is taken not to touch the heart because ventricular fibrillation is easily provoked. The purse-string suture is placed for the aortic cannula, the patient heparinized, and the cannula inserted and connected to the arterial tubing. Only then is a purse-string suture placed around the right atrial appendage; if the heart fibrillates, CPB can be established in less than a minute. A single venous cannula is inserted, and CPB begins with the perfusate at 34°C; the ductus arteriosus is ligated and cold cardioplegia administered. In the presence of aortic regurgitation to a degree that interferes with cardioplegia delivery, cardioplegia can be delivered via small olive tip catheters directly into the coronary ostia, or coronary sinus cardioplegia can be used.

A transverse aortotomy is made ( Fig 50.8 A). Two stay sutures are placed on the upstream side of the aortotomy for exposure. The aortic valve is inspected to determine which of the commissures to incise. Only partially formed commissures should be incised; commissurotomy should not be performed where there is only a rudimentary raphe ( Fig. 50.8 B).

Aortic valvotomy. (A) Operation is performed on cardiopulmonary bypass with aorta occluded. Electromechanical arrest of heart is achieved by infusion of cold cardioplegic solution. A transverse aortotomy is made above sinutubular junction to preserve integrity of aortic root. (B) Aortic valve is exposed by gentle retraction of aortotomy anteriorly. Valve is inspected to determine optimal location for incision of commissures. Only commissures with adequate cusp attachment to aortic wall are opened; rudimentary commissures (raphe) should not be incised. (C) Incision of commissure is deepened in stages, and cusps on each side are evaluated for lack of prolapse before further incision; incision is carried no further if prolapse is suspected. Usually, incision may be carried to aortic wall in well-supported commissures.

Aortic valvuloplasty is performed by dividing fused commissures with a knife to within 1 mm of the aortic wall; in neonates, the cusps are often gelatinous, but every effort still should be made to identify these commissures. It is important that even tension be placed on the two adjoining cusps so that incision is precise ( Fig. 50.8 C). Only commissures with adequate cusp/commissural attachment to the aortic wall are opened, because division of rudimentary commissures produces regurgitation. Incisions are deepened in stages, and cusps on each side are evaluated for competence and lack of prolapse before each further incision. If further incising of the commissure might cause cusp prolapse, the incision is carried no further. Occasionally, myxomatous nodules can be excised from the cusp’s free edge, or fibrous thickening can be shaved off the ventricular aspect of one or more cusps. The aortotomy is then closed with a continuous suture. If there is any degree of aortic regurgitation by saline filling of the aortic root, a 6-0 polypropylene suture (Frater stitch) can be placed through the midpoint of each cusp and brought out through the closed aortotomy. The suture is removed when left ventricular contraction begins.

The remainder of the procedure is completed as usual. A left atrial catheter should be positioned before discontinuing CPB. If the neonate is of suitable size for placing a transesophageal echocardiography (TEE) probe, the repair is evaluated before and after discontinuing CPB. Left ventricular and aortic pressures are measured and recorded before closing the chest.

After the establishment of CPB, the aorta is clamped and cold cardioplegic solution infused. A left atrial or left ventricular vent is used to facilitate visualization of the aortic valve. A transverse aortotomy is made and stay sutures applied to edges of the incision for exposure. Aortic valvuloplasty and a commissurotomy are performed as described earlier. In older patients the fused commissures can be thickened. In those cases, the fibrous tissue at the commissures is cored out, thinning the commissure. This is more effective in opening the commissure rather than doing only a simple commissurotomy.

The aortotomy is closed by continuous stitches, and the rest of the operation is completed as usual.

Pericardial cusp extension valvuloplasty procedures (as described by Duran) to compensate for deficiency of valvar tissue and increase the coaptation surface area have been applied primarily to regurgitant aortic valves (see Chapter 12 and Chapter 33 , Section II). More recently, encouraging midterm results with these techniques applied to congenital aortic stenosis (particularly with mixed lesions) support their inclusion as surgical options. Aortic cusp extension valvuloplasty may be considered as an adjunctive procedure to primary open valvotomy or in reoperative situations with recurrent aortic stenosis or regurgitation following previous valvotomy. Before proceeding with valve reconstruction, preoperative echocardiographic studies should ascertain the absence of left ventricular subaortic obstruction.

Following a median sternotomy, autologous pericardium is harvested, thoroughly cleaned of all fatty tissue and adhesions, treated with 0.625% glutaraldehyde solution for 3 to 5 minutes, and kept moist with normal saline. CPB, left ventricular venting, and myocardial management are performed as described under “Aortic Valvuloplasty in Older Infants, Children, and Adults.”

An oblique aortotomy is made and the aortic valve evaluated for presence of complete but fused commissures and a raphe in congenitally bicuspid aortic valves. Each cusp is examined for thickness and mobility, free-edge irregularities, and tissue deficiency.

The valve is prepared for cusp extension by first thinning the thickened cusp edges. Fused commissures are incised out to the aortic wall, and subcommissural fusion or scar tissue is released to maximize cusp mobility. Bicuspid valves with a rudimentary raphe are tricupidized by incising through the fused cusp at the raphe all the way to the aortic wall ( Fig. 50.9 ). The pericardial patches are each cut to a length determined by the diameter of the aorta, supplemented with an additional 15% to 20% to account for later pericardial shrinkage. Height of each patch is chosen to extend the line of coaptation of the repaired cusps about 5 mm higher than the highest cusp and to bring the extended cusps into a coaptation point in the center of the valve orifice. The pericardial extensions are sutured to each cusp with continuous 5-0 polypropylene, beginning in the center of the cusp and working toward the commissures. The extensions are attached to the aortic wall, creating neocommissures at the level of the sinutubular junction. Ilbawi and colleagues recommend leaving a little excess pericardial patch at the commissural level, secured with a pledgeted mattress suture through the aortic wall. With all the patch extensions in place, the newly constructed extensions are trimmed to provide a uniform cusp height and symmetric coaptation surface (see Fig. 50.9 ). Adequacy of the valve opening is examined, and initial valve competence is assessed by filling the aortic root with saline. Aortotomy closure and discontinuation of CPB are conducted as usual. Evaluation of valve function by TEE is performed before and following discontinuation of CPB. If aortic regurgitation is more than mild or if peak transvalvar gradient by TEE exceeds 30 mmHg, consideration should be given to reestablishing CPB and revising the valve repair or, if improvement is not feasible, proceeding with valve replacement.

Tricuspidization of bicuspid aortic valve. Raphe is split and cusps extended with glutaraldehyde-treated pericardium.

(From Pozzi M, Quarti A, Colaneri M, Oggianu A, Baldinelli A, Colonna PL. Valve repair in congenital aortic valve abnormalities. Interact Cardiovasc Thorac Surg . 2010;10:587-591.)

The neocuspidization technique as described by Ozaki is discussed in Chapter 33 , Section III.

When viewed at operation, the congenitally stenotic aortic valve may be too extensively deformed to be opened and remain reasonably competent. However, this situation is rare in primary operations in patients younger than age 10 and uncommon in those younger than 20. It is more common when multiple prior balloon valvotomies have been performed, and particularly when progressive or recurrent stenosis is accompanied by moderate or worse aortic regurgitation.

Aortic valve replacement in older children may be done in a standard fashion using a mechanical prosthesis (see “ Isolated Aortic Valve Replacement ” under Technique of Operation in Chapter 12 ). It may also be performed in the standard freehand manner using an aortic valve allograft (see “ Allograft Aortic Valve ” under Technique of Operation in Chapter 12 ) or a pulmonary valve autograft (see “ Autograft Pulmonary Valve ” under Technique of Operation in Chapter 12 ). Because the aortic root and LV-aortic junction may be quite small in young children who require aortic valve replacement, aortic root enlargement (see “ Root-Enlarging Technique ” under Technique of Operation in Chapter 12 ) or replacement (see “ Replacement of Aortic Valve and Ascending Aorta, En Bloc ” under Technique of Operation in Chapter 12 ) may be advantageous. An aortic allograft can be used as the replacement device, or a pulmonary autograft may be preferred. The autograft has the advantage of remaining unchanged and uncompromised by host reaction, and it also will grow.

Hospital mortality for surgical treatment of congenital valvar aortic stenosis in heterogeneous groups of patients younger than 20 to 25 years of age is not a meaningful value because of the important role of incremental risk factors for death and the selection processes by which treatments (or no treatments) are chosen.

Mortality varies widely among patient subsets, with few or no deaths after valvotomy in children and young adults. ^{, ,} Mortality is higher in neonates, but the potential safety of an open approach in neonates with severe congenital aortic stenosis has been demonstrated. ^, Still, the current preference in most centers is initial percutaneous balloon valvotomy. Multiple centers have achieved hospital mortalities of 15% or less in neonates. Again, however, mortality figures in heterogeneous groups of patients, even if all are neonates, are difficult to interpret, as demonstrated by Gaynor and colleagues and a Congenital Heart Surgeon’s Society (CHSS) analysis. In contrast to many situations in cardiac surgery, nearly all deaths after operation for congenital valvar aortic stenosis occur early postoperatively, most within 48 hours.

Success in salvaging such patients with emergency temporary extracorporeal membrane oxygenator (ECMO) or left ventricular assist device (LVAD) support has not been fully evaluated, but such support is advisable in the face of progressive circulatory failure (see “ Treatment of Low Cardiac Output ” in Chapter 4 ).

Hospital mortality after operations for congenital valvar aortic stenosis in patients older than age 1-year approaches zero.

Overall survival up to 40 years is good after the primary operation for congenital valvar aortic stenosis in older infants and children. ^, In very ill neonates and young infants, however, survival is compromised, primarily by high early risks.

A CHSS study of 320 neonates with critical aortic stenosis noted 1- and 5-year survival of 72% and 70%, respectively, among those receiving an initial procedure aimed at biventricular repair.

Almost all early deaths are in acute cardiac failure, and theoretically most should be preventable by (1) stabilization of critically ill neonates and others (with ECMO or LVAD support if needed) so that operation is not performed in NYHA class V patients as it was in the past and (2) proper myocardial management. In neonates and young infants, however, many deaths result from (1) failure to appreciate the importance of coexisting components of the spectrum of the hypoplastic left heart syndrome (see Chapter 51 ) and (2) nonoptimal selection, in particular a biventricular pathway rather than a single-ventricle pathway, at least in the present state of knowledge (see “ Indications for Operation ” later in this section).

Deaths occurring late after operation are in various modes, and inferences are made with difficulty. Thus “sudden death” has been reported as the mode of death in 12% of patients included in one long-term follow-up study, but the majority had severe residual or recurrent stenosis or severe aortic regurgitation. Among neonates for whom staging of repair is necessary for a univentricular pathway, few late deaths now occur between the cavopulmonary shunt stage and completed Fontan.

Most surviving patients, including those who have had reoperations, are in NYHA class I or II. Objective evidence of improvement in functional capacity is provided by Whitmer and colleagues, who demonstrated marked regression of exercise-induced ST depression 1 year after operation, as well as an increase in mean total work and peak exercise systolic blood pressure.

ECG evidence of left ventricular hypertrophy may persist after valvotomy or valve replacement either because of residual stenosis or regurgitation or a progressive secondary cardiomyopathy. Intraoperative damage to the LV or preexisting ischemic myocardial fibrosis exacerbated by delaying operation can contribute to or cause this condition. ^, Usually, however, left ventricular hypertrophy is reversible.

Preoperative inordinate left ventricular hypertrophy and wall thickness often found in children with congenital valvar aortic stenosis often regresses after successful valvotomy or valve replacement, which reduces left ventricular afterload and increases systolic function.

Pressure gradient usually is substantially reduced after aortic valvuloplasty and persists for 5 to 10 years. Thereafter, the gradient tends to rise steadily, occurring earlier and more frequently when valvotomy was necessary during the neonatal period or in infancy. In patients with a good initial result, the later rise in gradient is mainly the result of progressive cusp immobility and calcification. Recurrence and progression of LV-aortic pressure gradient is usually an indication for reintervention with either percutaneous balloon valvotomy or operation.

Following aortic cusp extension procedures with autologous pericardium, long-term durability of repair has been incompletely studied. Alsoufi and colleagues have emphasized the importance of satisfactory relief of aortic stenosis at the time of operation. Among 22 children who underwent this procedure, those with postoperative peak echocardiographic gradients of less than 30 mmHg had stabilization of their peak gradient over the next 2 to 3 years. However, progressive worsening of aortic stenosis was noted in those with early gradients exceeding 30 mmHg (moderate or greater aortic stenosis).

Important aortic valve regurgitation is uncommon after valvotomy when the operation has been performed as described. Moderate to severe regurgitation without residual stenosis is present at late follow-up in about 10% of patients, but some regurgitation is combined with moderate or severe residual or recurrent stenosis in an additional 15% to 20%. Postoperative regurgitation occurs more frequently when valvotomy is radical and particularly when an attempt is made to convert a bicuspid into a tricuspid valve.

The incidence of endocarditis is not lessened by valvotomy ^{, , ,} and may even be somewhat higher than in the natural history. ^,

Rarely, patients with severe valvar aortic stenosis who undergo surgical or balloon valvotomy as neonates or in infancy develop severe diastolic heart failure years later. Robinson and colleagues at Boston Children’s Hospital reported four such patients who presented 14 to 19 years after balloon valvotomy with heart failure and severe diastolic dysfunction. All had evidence of a confluent layer of left ventricular subendocardial hyperenhancement demonstrated by gadolinium-enhanced magnetic resonance imaging that was documented by histopathology in two patients to be EFE. One patient experienced clinical improvement following aortic valve replacement and extensive EFE resection. Robinson and colleagues hypothesize that EFE may result from early (possibly in utero) and irreversible myocardial damage induced by subendocardial ischemia secondary to persistent pressure overload with decreased ventricular flow, which may gradually progress irrespective of relief of left ventricular outflow obstruction.

As with time-related freedom from death, time-related depictions of freedom from reintervention and aortic valve replacement are of limited value when they are derived from a heterogeneous population.

In general, however, about 85% to 95% of children and young adults (excluding neonates and infants) are free of reintervention (usually valve replacement) for at least 10 years after the initial operation ( Fig. 50.10 ). Then, although constant in the intermediate term, the hazard function (rate of reintervention) begins to rise. By 20 years after initial operation, only 60% of patients will be free of reintervention, and by 40 years, only 10% will be free. The older the patient, the more likely it is that the reintervention will be valve replacement.

Cumulative incidence curves depicting time-related freedom from several unfavorable outcomes in 30 children and young adults (infants excluded) undergoing valvotomy for congenital valvar aortic stenosis. Vertical bars represent 70% confidence limits. Mean follow-up time was 13 years (1–17 years). Percentages refer to distance between curves. AVR, Aortic valve replacement.

(From Hossack KF, Neutze JM, Lowe JB, Barratt-Boyes BG. Congenital valvar aortic stenosis: natural history and assessment for operation. Br Heart J. 1980;43:561.)

Reintervention appears to be required at a shorter interval and in greater prevalence when the initial intervention has been performed in neonatal life or infancy and is more likely to consist of valvotomy than valve replacement. ^{, ,} Greater frequency of reintervention may be related to generally higher residual gradients in these cases. Reintervention appears to be required more frequently when initial valvotomy has been performed by some method other than an open operation using CPB. Reintervention rate increases 15 years after operation from about 0.7% per year to >2% per year ( P <.0001).

Procedures done at reoperation are generally more varied than at initial operation. A satisfactory repeat valvotomy is sometimes possible, especially when the initial operation was done in infancy. At times, an overlooked second level of obstruction is found that requires treatment such as patch graft supravalvar enlargement, a Konno procedure (see “ Technique of Operation ” in Section II), or an aortic root replacement (see “ Aortic Valve Replacement in Children ” under Technique of Operation earlier in this section). These reoperations carry a low risk but generally carry greater risk than primary operation.

Freedom from further reoperation following aortic valve cusp extension procedures has been variable, with freedom from subsequent aortic valve repair or replacement of 60% to 80% at 5 years and about 50% at 15 years. ^{, ,} Durability of repair appears greater if a tricuspid valve can be created. When the early valve function is considered optimal (mild or less AR and a postprocedure LVOT gradient of <35 mmHg), long-term durability is improved, with some reports of freedom from reoperation >75% at 10 years. ^, Thus, a good early result after valve repair including leaflet extension procedures offers an opportunity in most cases for a long interval before needing a Ross procedure or other valve replacement operations.

Neocuspidization (Ozaki procedure) has been expanded in the pediatric population for both aortic regurgitation and stenosis, with generally favorable outcomes as experience increases among many centers. An analysis of 57 patients with congenital aortic and truncal valve disease who underwent the Ozaki procedure included 24 with aortic regurgitation, 6 with aortic stenosis, and 27 with mixed stenosis and regurgitation. All but 1 patient were older than 1 year. The number of native valve cusps ranged from unicuspid to quadricuspid valves. Neoleaflet material included autologous in 20 and fixed bovine pericardium in 37. At discharge, 98% of patients had mild or less regurgitation, and peak aortic gradient was 17 ± 9.5 mmHg. Another analysis of the Ozaki procedure in older pediatric patients (median age 15 years) reported 3-year freedom from reoperation of 80%. A literature review identified 850 patients with hospital mortality of <2%. The cumulative incidence of aortic valve reoperation was 4%, most commonly related to endocarditis.

An analysis of the Australian experience with aortic valve reconstruction in older children and young adults included 3 leaflet neocuspidization in 70%, usually with autologous or tissue engineered bovine pericardium. The median age at operation was 15 years, and 40% had primary aortic regurgitation. Freedom from reoperation or moderate or greater aortic regurgitation was 94%, 85%, and 79% at 1, 2, and 3 years, respectively, with no difference between neo-tricuspidalization and single leaflet reconstruction. However, as longer follow-up becomes available, it is becoming clear that this technique has its limitations in pediatric age groups.

Bicuspidization procedures with leaflet augmentation have been a reasonable alternative to valve replacement for unicuspid valves, providing an effective bridge to valve replacement in younger patients. Matsushima and colleagues reported on 60 consecutive patients who underwent bicuspidization at ≤18 years of age between 2003 and 2018. Between 2003 and 2018, autologous pericardium, decellularized xenogeneic tissue, and expanded polytetrafluoroethylene (PTFE) were used in 45, 11, and 4 patients, respectively. Freedom from reoperation was 73% and 50% at 5 and 10 years, respectively.

The Ross Procedure for adult patients with aortic valve disease is discussed in Chapter 12 . Extensive experience has accumulated with the pulmonary autograft procedure in the pediatric population. Reported outcomes in neonates and small infants are generally less good than in older children. A literature review by Buratto and Konstantinov suggests that the hospital mortality for infants and neonates undergoing the Ross procedure exceeds 15%, with 10-year survival <80%. A single center analysis of a 27-year experience with the Ross procedure identified 58 infants at a median age of 63 (range 9–156) days, of which 18 (31%) were neonates. Hospital mortality was 19%. Risk factors identified by multivariable analysis included Shone complex (HR 17.6; P =.009), interrupted aortic arch with VSD (HR 16.0; P =.031), and younger age (HR 1.004; P =.005). The inflection point for increasing risk was about 45 days. Among 47 hospital survivors, 2 late deaths occurred at 2 and 13 years. The higher risk among neonates and infants is supported by the US Society of Thoracic Surgeons multicenter registry analysis of 2805 pediatric patients undergoing the Ross procedure between 2000 and 2018, which included 163 neonates (5.8%), 448 infants (16.0%), 1444 children (51.5%), and 750 teenagers (26.7%). Hospital mortality was 24% in neonates, 11% in infants, 1.5% in children, and 0.8% in teenagers ( P <.01).

The Ross procedure has been particularly successful when the predominant lesion is aortic stenosis. A single center analysis of 79 children and adolescents undergoing the Ross procedure reported 97% freedom from reoperation at 10 years. Similar excellent long-term outcomes and freedom from aortic root intervention have been reported by Al-Halees and colleagues in older pediatric patients. Among older children and adolescents, the supported Ross technique as recommended in adults (see Chapter 12 ) has been employed with success. Among 40 consecutive pediatric and young adult patients (median age 16 years; range 10–35 years) who underwent a supported Ross procedure from 2005 to 2018, Riggs and colleagues reported that 39 of 40 patients had mild or no aortic regurgitation and a median anulus z-score of 1.4, indicating minimal neoaortic root dilation. Freedom from aortic root dilation was 80% at 10 years.

The tendency for progressive aortic root dilation is particularly challenging when the primary lesion is aortic regurgitation, as in adults (see Chapter 12 ). An analysis of 125 patients between ages 1 and 18 years undergoing the Ross procedure as a total root replacement included 85 patients with aortic stenosis and 40 with aortic regurgitation or mixed. Severe aortic regurgitation or autograft reintervention occurred in 39% of the aortic regurgitation group and 9% of the aortic stenosis group at 15 years ( P =.02).

Other studies indicate that freedom from reoperation among infants is about 60% at 10 years compared to 90% in older children. The potential advantage of delaying the Ross procedure until later in childhood or adolescence, as a secondary procedure when possible, is supported by an analysis of outcomes comparing primary with secondary Ross procedures. A propensity score matching analysis of older children undergoing primary vs. secondary Ross reported freedom from autograft reoperation at 10 years of 82% in the primary Ross group compared with 97.0% in the secondary Ross group ( P =.03). The reasons for this observation remain unsettled, but may relate to a combination of external scar and fibrosis that limits root dilation and inflammatory changes in the reoperative setting, possibly including adventitial neovascularization in the neoaortic wall.

As expected, operations to replace the right ventricle-to-pulmonary artery (RV-PA) conduit are the most common surgical reintervention and are age-related. In a review of 124 pediatric patients undergoing a Ross procedure (median age 11 years), 25-year survival was 90%, freedom from autograft reoperation was 91%, and freedom from RV-PA conduit replacement was 67% . By multivariable analysis, only younger age was a risk factor for right ventricular outflow tract reoperation. Percutaneous pulmonary valve implantation is an option for some of these patients.

Percutaneous balloon aortic valvotomy for severe aortic stenosis in neonates was described by Rupprath and Neuhaus in 1985 and Lababidi and Weinhaus in 1986. ^, A large experience with this technique has accumulated since then, well summarized in the neonatal group by Zeevi and colleagues from Boston Children’s Hospital. They found no difference when the results were compared with those of surgical valvotomy in a previous era. Similar results have been reported by others. Balloon aortic valvotomy is also valuable as an emergency intervention for critical aortic stenosis in the unstable neonate and infant. New technology may improve results still further. ^,

In a Congenital Heart Surgeons multi-institutional study, 110 neonates for whom the strategy for management was biventricular repair were treated by either surgical ( n = 28) or percutaneous balloon ( n = 82) aortic valvotomy. Propensity score adjustment (see “ Clinical Studies with Nonrandomly Assigned Treatment ” in Chapter 7 ) was used to account for procedure selection bias and achieve comparability of patient characteristics. Time-related survival to age 5 years was similar after surgical and percutaneous balloon aortic valvotomy, as was risk of reintervention.

Moore and colleagues studied midterm results of balloon dilation of congenital aortic stenosis performed at Boston Children’s Hospital in 148 children, all more than 1 month old. Mortality was 0.7% and was successful in 87% of patients, with average peak gradient reduction of 56% ± 20%. At 8 years postoperatively, 95% were alive, but only 50% were free of another intervention (surgical or repeat balloon aortic valvotomy). Aortic valve regurgitation of grade 3 or higher occurred immediately after the procedure in 13% (CL 10%–16%) and was a major factor in determining another intervention.

In a recent experience, the results of neonatal balloon valvotomy are similar to surgical valvotomy in terms of mortality, relief of stenosis, duration of hospitalization, and reinterventions. However, postprocedure incidence of moderate or worse aortic insufficiency is considerably higher after balloon valvotomy (15% vs. <1%). The difference in aortic insufficiency relates to the “blind” nature of balloon valvotomy compared to the precision of open surgical valvotomy. The excellent outcomes with surgical valvotomy support surgery as the primary therapy in some centers. Another contemporary experience showed equivalent outcomes with balloon vs. surgical valvotomy among infants and neonates.

Repeat balloon aortic valvotomy is an effective palliative procedure for children with aortic valve restenosis. Repeat balloon valvotomy usually provides immediate gradient reduction comparable to the results reported with initial balloon valvotomy, with no increased risk of developing aortic regurgitation.

Hawkins and colleagues followed 60 patients for 1 to 110 months after balloon aortic valvotomy. Operation was required in 23 patients (38%), and aortic valve operation was required in 5% to 7% of patients per year after balloon aortic valvotomy. Aortic valve regurgitation was the predominant indication. Aortic valve repair was possible in 9 of 23 patients requiring operation after balloon aortic valvotomy. Aortic valve replacement was required in the remaining 14 patients.

Sandhu and colleagues showed that balloon aortic valvotomy can be effective in young adults with congenital aortic stenosis. Of 15 patients aged 16 to 24 years having balloon aortic valvotomy, three required aortic valve replacement for high residual gradient or severe aortic valve regurgitation. Immediate reduction of the pressure gradient by an average of 55% persisted for an average of 1.5 years. Equivalent results were found in 70 children.

Immediate, early, and probably midterm results appear to be essentially equivalent to operation in the neonate and child and perhaps in the young adult with congenital aortic stenosis. Balloon aortic valvotomy is not effective treatment for older adult patients, especially when aortic stenosis is the degenerative type. Application of percutaneous balloon aortic valvotomy seems to be determined by local preference at present.

When restenosis becomes severe or when symptoms develop with moderate restenosis, reoperation is indicated. Initially dysplastic valve cusps should not be a contraindication to reoperation, because in a number of patients the cusps have been more normal in appearance at reoperation than in early life. Although repeat valvotomy or valve replacement is usually required, subvalvar stenosis may have also developed and must not be overlooked. Important subvalvar stenosis is often associated with a small anulus, as well as some supravalvar narrowing. In this case a Konno operation, aortic root replacement operation, or Ross-Konno operation may be advisable.

Periodic enthusiasm for closed transventricular aortic valvotomy in critically ill neonates and young infants is motivated by high early mortality in this group. Closed transventricular dilations have been performed with Hegar dilators and balloon catheters designed for percutaneous use. ^, Considering the early mortality, need for reintervention, and amount of valvar regurgitation produced, however, no convincing evidence indicates that this method is as good as or superior to the techniques described under “Technique of Operation” earlier in this section.

A few groups have preferred to perform valvotomy under inflow stasis at normothermia or mild hypothermia. Operation under these circumstances is a semi-open one, and forceful stretching or tearing of the valve may result if exposure is not ideal. Currently, this technique is rarely utilized.

Ilbawi and colleagues reported use of extended aortic valvuloplasty, in which the commissurotomy incision is extended into the aortic wall around the cusp insertion, mobilizing the valve cusp attachment at the commissures and freeing the aortic insertion of the rudimentary commissure. They showed reduced aortic valve gradients compared with standard aortic valvotomy at 1.7 years after operation. The method has possible merit but has not had wide application. Kadri and colleagues, as well as Tolan and colleagues, have described similar operations in which the raphe or fused commissure of the larger cusp of a bicuspid aortic valve is incised, and a triangular piece of pericardium is folded and inserted between the free edges of the incised raphe. ^, Autologous or bovine pericardium is attached to the free edges of the incised raphe and vertically to the aortic wall. ^, This procedure produces a tricuspid valve and restores the deficient intercusp triangle, preventing cusp prolapse. Experience with this and other cusp reconstruction procedures (see “ Cusp Reconstruction ” under Technique of Operation earlier in this section) is limited, so caution should be used in applying these methods until more is known about their efficacy in palliating aortic valve stenosis.

Utilization of the Ozaki procedure in pediatric patients is discussed in the “Results” section earlier.

A gradually evolving experience has emerged with fetal application of percutaneous aortic balloon valvotomy. In a study of 58 fetuses undergoing balloon valvotomy at a median gestational age of 26.2 (20.3–32.2) weeks, technical success was achieved in 86%. Sixty-five percent of this group survived to delivery at a median gestational age of 38 weeks (range 29–40), but none of those without a successful valvotomy survived. Of the 74% of this surviving group who were candidates for a 2-ventricle circulation, >70% required an aortic valve procedure soon after birth. Overall survival among those with biventricular circulation was 79% at a median follow-up of 2 years. In another 10-year single center analysis, fetal aortic valvuloplasty (FAV) was considered in the presence of marked elevation of left ventricular pressure, reversal of flow in the transverse aortic arch, and a left ventricular length z-score > −1. Among 29 fetuses with severe aortic stenosis, the procedural mortality was 10%, pregnancy termination occurred in 10%, and 47% of postbirth survivors had biventricular circulation at 1 year. A meta-analysis of 389 fetuses concluded that FAV performed in experienced centers carries a low procedure-related mortality and high success rate in achieving a biventricular circulation.

Controversy remains about the choice of initial intervention although balloon valvotomy has been increasingly applied to symptomatic neonates with critical aortic stenosis. Some experienced centers continue to prefer surgical valvuloplasty on CPB under direct vision, with a lower incidence of postprocedure aortic insufficiency. Some centers are more likely to apply balloon valvotomy with a larger anulus and less complex valve pathology, whereas a small anulus with more complex valve pathology is more amenable to open valve repair.

Differing views exist about the timing of a Ross Procedure in early infancy. Some centers prefer to reserve the Ross for patients with two or more failed valve repairs, whereas others prefer earlier Ross as the “definitive” operation. However, most centers prefer to defer operation beyond infancy.

The aortic valve is usually tricuspid and either entirely normal or has some diffuse cusp thickening. The subaortic membrane can encroach upon the ventricular side of the aortic valve leaflets leading to varying degrees of aortic regurgitation. Trivial or mild aortic regurgitation is present in about two thirds of patients. The aortic valve, however, may be bicuspid, and congenital commissural fusion may produce varying degrees of valvar stenosis. The valve may have been damaged by endocarditis, a complication of subvalvar stenosis, ^, which can result in severe regurgitation. Rarely, the subaortic membrane may be infected. Bases of valve cusps are thick when a high-lying fibrous ridge is continuous with them.

Infrequently, supravalvar as well as valvar stenosis coexists with the subvalvar narrowing. This combination is at the mild end of the spectrum of hypoplastic left heart physiology.

The LV is usually concentrically hypertrophied. Subendocardial ischemia and probably fibrosis occur in subvalvar aortic stenosis as well as in congenital valvar stenosis. Rarely, there may be excessive hypertrophy of the septum (vs. thickening of the posterior left ventricular wall) and muscle fiber disorientation histologically. ^, This histology complicates the distinction in a few patients between discrete subvalvar aortic stenosis and HOCM.

Roberts and his group have noted coronary artery luminal narrowing due to structural wall changes of intramural coronary arteries in both humans and dogs with fibrous subvalvar aortic stenosis. ^, These changes have not been observed in valvar aortic stenosis.

Discrete subvalvar aortic stenosis occurs as an isolated anomaly in only about half to two thirds of patients coming to operation. ^{, ,} Coexisting anomalies include a VSD that is frequently large, ^{, ,} and the fibromuscular obstruction is then often located immediately below (upstream to) the VSD. When there is aortic arch interruption and patent ductus arteriosus or occasionally coarctation, localized muscular subvalvar stenosis may be associated with a subpulmonary VSD. ^, Valvar or infundibular pulmonary stenosis and occasionally tetralogy of Fallot, atrial septal defect, aortopulmonary window, sinus of Valsalva aneurysm, and aneurysm of the membranous ventricular septum may also coexist, occurring more frequently in pediatric surgical patients.

The complex relationship between VSD and discrete subvalvar aortic stenosis is further evidenced by stenosis developing after spontaneous closure or narrowing of the VSD. Typical discrete subvalvar aortic stenosis may also develop both before and after repair of a complete atrioventricular (AV) septal defect, repair of coarctation, LV-to-aorta internal rerouting in double outlet right ventricle or transposition with VSD, and other forms of congenital cardiac anomalies.

Localized subvalvar aortic stenosis may be caused by morphology and mechanisms other than those just described. In an autopsy series that included complex congenital heart disease, Freedom and colleagues found the typical fibrous or fibromuscular variety to be the least common in infancy. Mitral valve anomalies involving accessory tissue or leaflet malposition (including that found in AV septal defects) may be a cause of obstruction and may occur in the absence of functional abnormality of the mitral valve or other cardiac anomalies. Localized muscular obstructions related to abnormal infundibular development or malalignment are frequent and often associated with a VSD and aortic coarctation or interruption. A developmental complex described by Shone and associates consists of a parachute mitral valve and left ventricular outflow tract obstruction that usually includes localized fibromuscular subaortic stenosis. Discrete muscular subvalvar aortic stenosis may develop after pulmonary trunk banding for VSD.

Symptoms of congenital subvalvar aortic stenosis are similar to those of the valvar variety. About 25% of patients requiring operation are asymptomatic despite presence of important obstruction.

A systolic ejection murmur is heard, but a click is rare. There is an unimpressive aortic diastolic murmur in 65% of patients. It is secondary either to (1) cusp thickening with or without adherence of the fibrous ridge to the cusps or (2) effects of eddy currents produced by the subvalvar stenosis upon aortic valve closure.

When severe stenosis is present, the pulse is slow rising, the second heart sound is single or paradoxically split, a third and occasionally fourth heart sound are audible, and a mid-diastolic murmur may be heard at the apex, usually in association with a fibrotic obstruction that limits anterior mitral leaflet movement. It is important to recognize, particularly in children, that one or more of these signs may be minimal or absent despite severe obstruction.

Occasionally, aortic regurgitation may be caused by severe congenital cusp deformities or infective endocarditis. When endocarditis occurs on the aortic valve, signs of regurgitation produced by cusp destruction may be less than expected because a tight fibrous stenosis beneath the valve may limit aortic runoff. Moreover, vegetations on the fibrous shelf itself may increase subaortic obstruction.

The ascending aorta is not usually dilated in the chest radiograph, and valvar calcification is absent. The LV is usually enlarged.

The ECG usually shows severe left ventricular hypertrophy.

Two-dimensional echocardiography can be diagnostic, accurately demonstrating and outlining the obstructing shelf ^{, ,} ( Fig. 50.12 ). The technique is so sensitive that it can demonstrate a subvalvar discrete lesion before a gradient develops. Color flow Doppler imaging sufficiently defines the gradient across the obstruction to allow a definitive decision regarding operation. Sigrusson and colleagues suggested that the angle formed by the septum and aorta (aortoseptal angle) may have prognostic value in patients with discrete subaortic stenosis, because it is steeper in patients with subaortic stenosis than in normal persons. They suggested this anatomic feature may be causative in development of this condition. M-mode echocardiography is helpful in differentiating this lesion from HOCM. ^,

Two-dimensional echocardiogram in localized discrete subvalvar aortic stenosis. Fibromuscular ridge is observed narrowing left ventricular outflow tract below aortic valve.

Cardiac catheterization shows a systolic pressure gradient below the valve on withdrawal of the catheter across the left ventricular outflow tract. When the fibrous ridge is immediately beneath the valve, the gradient may be apparent at valve level. Postectopic pressure pulse response is normal, and the aortic pulse contour does not show an accessory wave; these features distinguish the lesion from HOCM.

Angiography supports the definitive diagnosis. ^{, , ,} The tilted left anterior oblique (LAO) view provides good visualization of the fibrous ridge because it overcomes the foreshortening of the left ventricular outflow tract region present in the conventional LAO projection ( Figs. 50.13 through 50.15 ). Level and thickness of obstruction can be accurately defined in this manner, and additional valvar stenosis and regurgitation also can be evaluated.

Left ventricular cineangiogram in cranially tilted left anterior oblique projection in patient with localized discrete fibrous subvalvar aortic stenosis, in diastole (A) and early systole (B). A thin ridge obstructing left ventricular outflow tract about 1 cm below aortic valve is well profiled and indicated by white arrows. In systole, aortic valve is domed (arrows) , indicating a valvar abnormality in addition to subaortic ridge. a, Anterior mitral leaflet; Ao, aorta; L, left; LV, left ventricle; N, noncoronary sinus; R, right coronary sinus.

Left ventricular cineangiogram in cranially tilted left anterior oblique projection in patient with fibromuscular subvalvar aortic stenosis. Cineangiogram frame in systole shows thick fibromuscular outflow obstruction commencing just beneath aortic valve. Aortic cusps fail to open completely but show no doming. Diverticulum just below obstructing shelf on septal aspect of outflow tract represents a surgically closed ventricular septal defect (arrow).

Left ventricular cineangiogram in lateral projection in patient with tunnel subvalvar aortic stenosis. Cineangiogram frame in late systole shows outflow tract narrowing 1 cm below aortic ring and extending down into base of left ventricle. Anterior mitral valve leaflet forms posterior margin of stenotic zone (arrows) and is prevented from moving back to its normal systolic position. Anterior (septal) margin of outflow tract shows irregular encroachment by obstructing fibromuscular tissue.

In discrete subvalvar aortic stenosis, features characteristic of HOCM are usually absent. Rarely, however, particularly in severe forms of fibrous subvalvar aortic stenosis, including the tunnel variety, there may be abnormal systolic anterior motion (SAM) of the mitral leaflet and an abnormal postectopic response. These signs indicate either a particularly prominent anterior muscular shelf or, in patients who also show an abnormal septal to posterior wall thickness ratio on echocardiography (with disorientation of the muscular pattern of hypertrophy histologically), associated HOCM.

Preparation for operation for congenital subvalvar aortic stenosis in children is accomplished as described for valvotomy in Section I. Fig. 50.16 shows anatomic relationships of the subaortic fibromuscular ridge.

Anatomic relations of left ventricular outflow tract in subvalvar aortic stenosis. In this view, heart is bisected; anterior aspect is on left and posterior aspect on right. Inset shows subaortic ridge and left bundle branch of specialized conduction system below the surface of the ventricular septum, with nadir of right coronary cusp marking leftward limit of conduction system. Deep incision of ventricular septum is possible to the left of the midpoint of right coronary cusp.

A transverse aortotomy is made ( Fig. 50.17 A). The aortic cusps are retracted and the subvalvar fibrous ridge exposed. There is great variability in the nature and extent of the subvalvar ridge. Some are easy to remove by simple enucleation. Others are more extensive, requiring a more radical excision. The following description of operation is for the extensive forms.

Repair of discrete fibromuscular subvalvar aortic stenosis. (A) Operation is performed on cardiopulmonary bypass with aorta occluded. Cold cardioplegic solution is infused to achieve total electromechanical arrest. A transverse aortotomy is made. (B) Subaortic ridge is exposed by retracting right coronary cusp. Broken lines indicate proposed incision points. (C) Scalpel is used to make two incisions through fibromuscular ridge, with one below the commissure between right and left aortic valve cusps and the other parallel to first incision and beneath the nadir of right coronary cusp. Septal myocardium is removed deeply between the two incisions. (D) Fibrous ridge is dissected from the septum to the right and over anterior leaflet of mitral valve using a Freer septum elevator. Deep incision of ventricular septum carries hazard of heart block. Similarly, deep incision over anterior leaflet of mitral valve risks its perforation.

Beginning beneath the nadir of the right coronary cusp, a vertical incision is made through the ridge and into the underlying muscle, with depth of incision proportional to estimated septal thickness ( Fig. 50.17 B). A second incision parallel to the first is made through the ridge below the commissure between right and left aortic valve cusps. Excision of the fibromuscular ridge begins by carrying a vertical incision circumferentially between the parallel incisions ( Fig. 50.17 C), removing fibrous tissue and myocardium deep into the ventricular septum until the mitral apparatus is encountered at the leftward extremity of the left ventricular outflow tract. In this process, care is taken not to penetrate the ventricular septum and produce a VSD. As the dissection is carried down over the anterior mitral leaflet, only the fibrous ridge is removed, shaving it off the leaflet or mitral-aortic anulus with the knife or a Freer septum elevator ( Fig. 50.17 D). Dissection is carried rightward as far as the mitral leaflet and mitral-aortic anulus extend.

Returning anteriorly, only the fibrous ridge is shaved off the muscular septum to the right of the nadir of the right coronary cusp using a knife or septum elevator (see Fig. 50.17 D). The ridge excision is carried rightward over the membranous septum. This technique preserves the integrity of the underlying bundle of His and cores out the entire subvalvar stenosis as a single mass. When the fibromuscular ridge is attached to the undersurface of the belly of one or more of the aortic cusps, it is carefully shaved away from the cusp tissue.

The procedure is not considered complete unless a generous amount of muscle has been removed leftward of the nadir of the right coronary cusp. If only the fibrous component has been enucleated, a deep trough of muscle is cut from the ventricular septum anteriorly. The trough is centered beneath the commissure between the right and left aortic valve cusps as in the operation for HOCM (see “ Technique of Operation ” in Chapter 19 ). This step is of value even when the fibrous ridge is immediately subvalvar, because the ventricular septum is always hypertrophied.

Yacoub and colleagues propose mobilization of the left and right fibrous trigones along with extensive resection of all components of the subvalvar fibrous ring. Their proposition is based on the concept that the aortic and mitral orifices interact, with the fibrous trigones acting as a hinge mechanism for movement of the subaortic curtain and anterior mitral leaflet during the cardiac cycle. The incision to resect the fibrous ring is extended laterally at the location of the left and right fibrous trigones to excise this fibrous tissue in continuity with the obstructing ring. Resection of the left fibrous trigone carries the risk of creating an opening to the outside of the heart or into the anterior mitral leaflet, and injury to the conduction system could occur during resection of the right fibrous trigone. The technique was used in 57 consecutive patients operated on over the course of 25 years without these complications occurring. Pressure gradient over the left ventricular outflow tract after the repair ranged from 0 to 30 mmHg (mean 8 mmHg), and no change in gradient was observed on follow-up assessment.

After determining that the ventricular septum has not been perforated and aortic valve cusps have not been damaged, the aortotomy is closed and the remainder of the procedure accomplished as described under “Technique of Operation” in Section I for valvotomy.

Aortic valve replacement may be required in some older children or adults when important aortic valve regurgitation coexists with severe subaortic stenosis. Modification of the Ross and Konno procedures is used in these patients (Ross-Konno procedure). CPB is established using two cannulae for venous drainage (with venae cavae tourniquets). The aorta is clamped and antegrade and retrograde cold cardioplegia administered through a cannula in the coronary sinus (see “ Technique of Retrograde Infusion ” in Chapter 3 ), directly into the coronary ostia, or both. The ascending aorta is divided and aortic valve excised. The coronary ostia are mobilized with a rim of sinus aorta, and the noncoronary sinus aorta is removed (see Chapter 12 ). The pulmonary trunk is removed from the right ventricular outflow tract in the usual manner for a Ross procedure (see “ Autograft Pulmonary Valve ” under Technique of Operation in Chapter 12 ). A slightly longer portion of the right ventricular outflow tract below the pulmonary valve may be removed ( Fig. 50.18 A). A short incision is made through the fibrous tissue of the aortic valve attachment at the nadir of the right coronary sinus into the ventricular septum, as in the Konno procedure ( Fig. 50.18 B). This incision is not as deep into the septum as in the Konno procedure, however, and should not extend beyond the medial papillary muscle (Lancisi) of the tricuspid valve to avoid injury to the first septal branch of the left anterior descending coronary artery. The fibromuscular subaortic ridge is excised and septal myocardium shaved from the left side to reduce thickness of the hypertrophied ventricular septum to widen the left ventricular outflow tract and completely relieve the obstruction ( Fig. 50.18 C). The pulmonary autograft is then sutured to the left ventricular outflow tract ( Fig. 50.18 D). The lengthened tongue of the attached right ventricular outflow tract is sutured to the depth of the incision in the ventricular septum. If no extra length of right ventricular outflow tract has been removed, the pulmonary autograft is simply inserted deeply into the left ventricular outflow tract. Al-Halees described the Mini-Ross-Konno procedure: a modified simplified technique allowing relief of LVOTO without the need to create a VSD.

Repair of complex subvalvar aortic stenosis requiring aortic valve replacement by pulmonary autograft (Ross-Konno procedure). (A) Operation is performed on cardiopulmonary bypass with aorta occluded and cold cardioplegia infusion for myocardial management. Aorta is divided and aortic valve excised. Coronary arteries are mobilized with a button of sinus aorta. Rest of sinus aorta is removed. Pulmonary trunk is divided at its bifurcation and removed from right ventricular outflow tract. An extension of the anterior wall of right ventricular outflow tract may be included to fill defect in ventricular septum created by the Konno incision. (B) An incision is made into ventricular septum (Konno) at the midpoint of right coronary sinus of Valsalva. This incision is not nearly as deep into ventricular septum as in the classic Konno operation and ordinarily would not pass the depth of the medial papillary muscle (Lancisi) of the tricuspid valve to avoid injury to first septal branch of left anterior descending coronary artery. (C) Subaortic obstructing ridge is cut away from ventricular septum on left side. Hypertrophied ventricular septum is shaved down on left side to achieve an unobstructed left ventricular outflow tract. (D) Pulmonary autograft is attached to ventricular septum with interrupted polypropylene stitches. Anterior extension of right ventricular outflow tract may be beneficial when incision of ventricular septum is extensive and deep.

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