Infants with critical pulmonary stenosis may present in the newborn period with severe cyanosis and heart failure. The clinical manifestations are relative to the severity of the stenosis and the patency of a foramen ovale or an atrial septal defect (ASD). In most children with pulmonary valve stenosis and intact ventricular septum, symptoms develop more slowly. Most patients are initially identified by a harsh systolic ejection murmur and a thrill over the pulmonic region on physical examination. An electrocardiogram usually reveals right-axis deviation, prominent P waves, and right ventricular (RV) hypertrophy. A chest radiograph may show prominent pulmonary artery shadows secondary to poststenotic dilation. The heart shadow is normal except in severe cases with congestive failure. Subsequent studies should include echocardiography to establish the severity of the lesion and identify associated abnormalities. Doppler evaluation allows estimation of the gradient across the valve and RV outflow tract. Finally, cardiac catheterization may be performed for additional diagnostic information, hemodynamic data, and for possible therapeutic intervention with balloon valvotomy.

Patients with pulmonary valve stenosis and intact ventricular septum require intervention for symptomatic lesions and for significant transvalvular pressure gradients. Historically, surgery was the mainstay of therapy for isolated pulmonary valvar stenosis. Currently, however, catheterization with balloon valvotomy has replaced surgery as the cornerstone of initial treatment. In cases of recurrent stenosis, repeat balloon valvotomy may be attempted before surgical therapy. The incidence of pulmonary insufficiency after balloon valvotomy is high (80%), but it is often clinically mild and well tolerated in most patients. Failed balloon valvotomy can be an indication for urgent surgical intervention. Surgical pulmonary valvotomy may be performed as an open technique using cardiopulmonary bypass or more rarely through a closed transventricular approach. Operative mortality is minimal except in cases of critical stenosis with associated RV hypoplasia and congestive heart failure. The results of treatment are directly related to the size of the RV chamber and the age of the patient at presentation.

Exposure for open pulmonary valvotomy is obtained through a median sternotomy. After heparinization, an aortic cannula is placed in the ascending aorta, and bicaval cannulation is performed. Snares are placed around the inferior and superior venae cavae. A catheter is placed in the ascending aorta for the antegrade delivery of cold blood cardioplegia. A patent ductus arteriosus must be ligated or snared at the initiation of cardiopulmonary bypass. An aortic cross-clamp is applied, and cardioplegia is delivered antegrade to achieve myocardial arrest. The snares are secured around the venous cannulae. The procedure may also be performed without a cross-clamp and cardioplegic arrest if there is no atrial or ventricular communication present.

A longitudinal pulmonary arteriotomy is performed above the level of the valve commissures. The stenotic valve is inspected, and the fused commissures are identified and carefully incised with a no. 11 scalpel blade. The incisions should extend to the annulus (Fig. 91.1A, and 91.1B). Any valvar adhesions to the pulmonary arterial wall are sharply incised. A partial valvectomy may be performed to remove thickened valve tissue or dense scarring on the leaflets. Dysplastic portions of the valve may require excision. The infundibulum is then inspected through the valve for any residual subvalvular stenosis. Sharp infundibular resection through the valve should be performed if necessary. Rarely, a ventriculotomy is required with an infundibular or transannular patch closure. If a small annulus is present, a Hegar dilator may be used to size the valve annulus. The need for a transannular patch can be determined based on this measurement. If there is supravalvular hypoplasia, a pericardial patch is used to close the incision in the pulmonary artery from the annulus to the base of the left pulmonary artery. The arteriotomy is otherwise closed with a running polypropylene (prolene) suture.

If there is evidence of an ASD or patent foramen ovale, a right atriotomy is performed and the atrial septum is inspected. Closure of a patent foramen ovale or ASD is performed using primary closure or pericardial patch closure with a running prolene suture technique. The tricuspid valve (TV) leaflets are retracted to expose the infundibular outflow tract. Infundibular resection may be performed through the TV to relieve any remaining stenosis. The TV is tested for competence before closure. The atriotomy is then closed
in a two-layer manner with a running prolene suture.

The patient is weaned from cardiopulmonary bypass. If the right ventricle is hypoplastic, a patent foramen ovale is left partially open. Measurements of pressure in the right ventricle and the main pulmonary artery will document any residual gradient and should be performed before decannulation. Intraoperative transesophageal echocardiography is used to assess any residual gradient or pulmonary valve insufficiency. There is often a small residual gradient across the valve postoperatively, which may regress with time.

If a restrictive patent foramen ovale is present or the atrial septum is intact, pulmonary valvotomy may be performed using a closed technique that avoids the use of cardiopulmonary bypass. A wet pump should be available on standby for possible use if necessary. A median sternotomy is used, and a purse string of 4-0 prolene suture is placed on the anterior aspect of the right ventricle just below the infundibulum. A 14-gauge angiocatheter with a pressure transducer is first introduced through the right ventricle into the pulmonary artery. Hegar dilators of progressively larger sizes (up to 7 or 8 mm) are then introduced across the valve. If the membrane does not dilate easily, a long vascular clamp can be passed through the purse string and right ventricle to disrupt the valve membrane. We now prefer the use of a balloon dilation catheter with a balloon, 1 mm larger in diameter than the annulus of the pulmonary artery. The balloon can be positioned by measurement and by palpation. A needle pressure transducer is then used to assess the remaining gradient across the valve. After adequate dilation is achieved, the purse string is tied and an additional reinforcing suture is placed in the ventricular epicardium.

Most patients with pulmonary stenosis are operated on electively with routine preoperative and postoperative care. Neonates with critical stenosis should be stabilized in the intensive care unit and operated on as soon as possible. Acidosis, electrolyte abnormalities, and congestive heart failure are corrected preoperatively.

These patients may also have stenosis in the infundibular region secondary to RV myocardial hypertrophy. Inotropes must be used with caution in the preoperative and postoperative periods because increased contractility may cause increased dynamic obstruction across the pulmonary outflow tract and further compromise pulmonary blood flow.

Diagnosis of this lesion is usually made in neonates and is prompted by the presence of hypoxia in varying degrees in the newborn period. Physical examination findings are often remarkable for prominent cervical venous pulsations and hepatic enlargement. A significant murmur is indicative of tricuspid regurgitation or may be related to the patent ductus arteriosus. An electrocardiogram shows progressive evidence of right atrial enlargement with peaked right atrial P waves. A chest radiograph is unremarkable at birth but may later reveal an increased cardiac shadow secondary to right atrial and left ventricular enlargement. The diagnosis of pulmonary atresia with intact ventricular septum is usually made by two-dimensional echocardiography. Ventricular cavity sizes, valve dimensions and function, and the nature of the pulmonary artery obstruction can be determined by echocardiography. Cardiac catheterization is used for a definitive diagnosis and further evaluation. Information determined during right and left heart catheterization should include the size and competency of the TV, the functional status of the ventricles, the degree of RV hypoplasia, the degree of infundibular hypoplasia, the presence or absence of coronary sinusoids and their communications with the anatomy of the coronary arteries, and the size of the pulmonary arteries. In addition to an injection of contrast medium into the right ventricle, selective coronary angiograms are required to assess the native coronary anatomy, particularly in the severely hypoplastic RV group. Newborns with hypoxemia and poor perfusion in spite of medical management should be assessed for the presence of a restrictive ASD, which can be enlarged by balloon septostomy at the time of catheterization. If the ductus arteriosus is closed or restrictive, prostaglandin E1 (PGE1) is infused to open the ductus. In the current era, a role is developing for stenting of the ductus arteriosus at the time of catheterization as an initial palliative intervention.

Our initial management of patients with PA/IVS is based largely on an anatomic classification, which specifically defines the degree of RV hypoplasia and the TV annular size measured as a Z-score. This classification not only allows initial management strategies but also has predictive value for the possible use of the right ventricle in subsequent definitive biventricular repair. The Z-score is determined by comparing the diameter of the TV (as measured by echocardiography) to the “expected” size and calculating the difference in standard deviations. This allows for a quantitative assessment of the degree of hypoplasia of the TV, which in most patients varies directly with the degree of hypoplasia of the RV. We and others have found both the degree of RV hypoplasia and the TV Z-score correlate with short- and long-term outcomes of surgical management of PA/IVS.

In this classification, neonates with PA/IVS are initially separated into three groups of mild, moderate, and severe RV hypoplasia. In patients with mild RV hypoplasia, the TV and RV cavity are approximately two-thirds or greater of calculated normal size and the RV outflow tract is well developed. This usually correlates with a Z-score for the TV of 0 to -2. In patients with moderate RV hypoplasia, the TV and the RV cavity are approximately one-half of calculated normal size (with a range of one-third to two-thirds normal), and the outflow tract is developed enough to allow an effective pulmonary valvotomy. This usually correlates with a Z-score for the TV of -2 to -4. In patients with severe RV hypoplasia, the TV and RV cavity are one-third or less of calculated normal size and the outflow tract is severely hypoplastic or obliterated and is often not amenable to an effective pulmonary valvotomy. This usually correlates with a Z-score for the TV of -4 to -6. Our approach is not based on a single anatomic finding but instead assesses the overall RV morphology and the degree of both TV and RV hypoplasia.

The TV is often anatomically and functionally abnormal in patients with PA/IVS. Therefore, a TV Z-score or valve diameter alone may not adequately predict the likelihood of achieving a biventricular repair. Similarly, some patients with only moderate RV hypoplasia may have a severe tricuspid malformation and ultimately undergo a single-ventricle approach with a Glenn or Fontan procedure. In addition, the compliance of the abnormal right ventricles with significant ventricular hypertrophy and small cavity size may limit the possibility of a complete two-ventricle repair even in those with only moderate hypoplasia.

A fourth subgroup of patients may present with marked cardiomegaly caused by right atrial enlargement, severe tricuspid regurgitation, and an Ebstein’s anomaly of the TV. Dilation and dysfunction of the right atrium (RA), RV, and ventricular septal wall in these patients often compromise left ventricular function and lead to biventricular failure. These patients may have significant compromise of the left ventricle by the dilated right ventricle, and the inefficient flow of blood in and out of the right ventricle compromises overall systemic blood flow. The creation of an aortopulmonary shunt may stabilize pulmonary blood flow in these patients, but the effect of the dilated right ventricle on systemic cardiac output may remain. Patch closure of the TV is usually not suitable for these patients, because there will be no outflow of the coronary sinus return, and often sinusoidal connections and Thebesian vessels into the right ventricle cannot then be decompressed. Surgical intervention in these patients is associated with >50% mortality. In these patients, the best approach may be early cardiac transplantation.

During the initial evaluation of patients with PA/IVS, particular attention must be paid to the anatomy of the coronary circulation. Abnormalities of the coronary circulation are often found in the severely hypoplastic group and may dictate which surgical management option is indicated. During fetal development, RV hypertension may cause intramyocardial sinusoids to develop. These sinusoids often communicate by fistulas with the coronary artery circulation. The morphology of these sinusoids and their specific communications are extremely variable. Proximal coronary artery stenosis or obstruction may develop in a native coronary artery supplied by these intramyocardial sinusoids. If the distal coronary artery flow is dependent on these sinusoids for adequate myocardial perfusion, they are termed RV-dependent coronary circulations (RVDCCs). Decompression of the right ventricle in these patients is contraindicated as it may lead to acute myocardial ischemia and death. A limited experience has shown that a shunt from the aorta to the right ventricle may be beneficial in these patients to augment myocardial perfusion and coronary blood flow.

Most infants with PA/IVS will require surgical management early in life to survive.
Treatment with intravenous PGE₁ will maintain pulmonary flow through the patent ductus arteriosus and allows time for evaluation and interventional decision making. Recently, some neonates have been successfully palliated with stenting of the ductus arteriosus at the time of catheterization. This has allowed delay of surgical intervention in those neonates who would otherwise be treated with a central shunt as an initial palliation. The efficacy of this catheter-based therapy appears promising for some neonates with PA/IVS, but the indications remain to be defined. Once the anatomy and morphology of these lesions have been identified at cardiac catheterization, classification is determined, and an appropriate operative strategy is planned. Delay in surgical treatment is often hazardous and may reduce survival. The primary goals of initial therapy should be to minimize early mortality and maximize the potential for a biventricular repair later in life. The choice of surgical approach is based on the anatomic classification previously described (Table 91.1).