Background
Pulmonary atresia with intact ventricular septum (PAIVS) is a rare congenital cardiac lesion characterized by heterogeneous right ventricular development, an imperforate pulmonary valve, and possible extensive ventriculocoronary connections. Prognosis and management depend on the degree of right ventricular hypoplasia (including tricuspid valve hypoplasia) and the dependency of the myocardial blood supply on abnormal communications between the right ventricle and coronary arteries. These two factors are the most important prognostic determinants.
Pathophysiology
The pulmonary atresia with intact ventricular septum (PAIVS) spectrum ranges from a normal-sized or slightly hypoplastic tripartite right ventricle with a well-formed infundibulum and imperforate pulmonary valve with commissural fusion to a diminutive unipartite right ventricle, narrowed or atretic infundibulum, primitive pulmonary valve, and ventriculocoronary artery connections (with or without stenoses). In PAIVS, the tricuspid valve is rarely normal and demonstrates a continuum of abnormalities, ranging from severe stenosis (often related to annular hypoplasia) to severe regurgitation. In addition, PAIVS has an obligatory right-to-left atrial-level shunt (through a patent foramen ovale or secundum atrial septal defect). Pulmonary blood flow usually depends on a patent ductus arteriosus. Aortopulmonary collaterals that originate from the descending thoracic aorta are rare.
Etiology
As with many forms of congestive heart disease (CHD), the genetic cause of pulmonary atresia with intact ventricular septum (PAIVS) is unknown. Kutsche and Van Mierop suggest that PAIVS probably occurs relatively late in cardiac morphogenesis after cardiac septation compared with pulmonary atresia with ventricular septal defect. [1] This may reflect a prenatal inflammatory or infectious condition; however, no histopathological evidence currently supports this view.
In rare familial cases, some researchers advocate a single gene theory.
Epidemiology
United States statistics
Despite overall low prevalence, pulmonary atresia with intact ventricular septum (PAIVS) is one form of cyanotic congenital heart disease (CCHD) that usually presents during the immediate neonatal period as the ductus arteriosus closes (along with transposition of the great arteries, tricuspid atresia, and pulmonary atresia with ventricular septal defect). PAIVS has no known genetic etiology, although rare familial cases have been described. PAIVS occurs in 7.1-8.1 per 100,000 live births and in 0.7-3.1% of patients with congenital heart disease (CHD).
International statistics
PAIVS occurs in 4.5 per 100,000 live births in the United Kingdom and Ireland.
Age-related demographics
PAIVS is a cyanotic congenital heart lesion that presents in the immediate newborn period coincident with closure of the patent ductus arteriosus.
Prognosis
Although outcomes have improved, surgical procedures (biventricular or univentricular strategies) are still associated with high mortality and morbidity. [2] Prognosis depends on the specific anatomy and type of intervention (univentricular, 1.5-ventricle, or biventricular correction). Overall survival is approximately 64-76% at age 5 years; however, single institutions report improved intermediate-term outcomes in relatively small series.
Karamlou et al [3] reported long-term functional health status and exercise capacity in 122 patients with pulmonary atresia with intact ventricular septum (PAIVS) following univentricular, 1.5-ventricle, or biventricular repair (mean 14 y). Participants had lower functional health status scores in domains of physical functioning compared with age- and sex-matched normal controls. Exercise capacity was higher in 1.5-ventricle repair patients, whereas functional health status measures were higher in biventricular repair patients. Peak oxygen consumption was low across all groups and correlated with larger initial tricuspid valve z-score.
Morbidity/mortality
Early survival depends on maintaining ductal patency until a palliative procedure can be performed to establish a reliable source of pulmonary blood flow. In those cases with an adequate-size right ventricle, transcatheter perforation of the pulmonary valve and maintaining patency of the ductus arteriosus can result in a biventricular circulation without the need for surgical intervention. In those cases requiring an additional source of pulmonary blood flow for an extended time period, placement of a systemic-to-pulmonary artery shunt or arterial ductal stenting may be appropriate in selected cases. [4, 5]
In both the short- and long-term, patients are at risk for sudden death, angina, arrhythmias, and congestive heart failure (CHF), in addition to complications of prolonged cyanosis and hypoxemia. The overall probability of survival for patients with PAIVS is approximately 65-82% at age 1 year and 64-76% at age 5 years, which is directly dependent on the degree of right heart hypoplasia. Note the following:
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Sudden death, angina, and arrhythmias: PAIVS is associated with ventriculocoronary connections in approximately 45% of patients and correlates directly with the severity of right heart hypoplasia. Because coronary artery stenoses are present in nearly 9% of patients, the coronary circulation is considered dependent on right ventricular systolic events. These patients are at particularly high risk for myocardial ischemia, angina, ventricular arrhythmias, and sudden death compared with patients who have other forms of congenital heart disease (CHD).
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CHF: Depending on the particular anatomic substrate, these patients may have an early predilection for heart failure due to both tricuspid regurgitation and increased pulmonary blood flow via a large systemic-to-pulmonary artery shunt. Postoperatively, the risk of heart failure may continue, depending on the ratio of pulmonary-to-systemic blood flow and on the degree of tricuspid and pulmonary regurgitation (following possible right ventricular outflow-tract reconstruction or pulmonary valvotomy). Most late reoperations following biventricular repair are pulmonary valve replacements.
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Cyanosis: Long-term complications of cyanosis and hypoxemia include polycythemia and a hyperviscosity syndrome. These patients may develop headache, decreased exercise tolerance, and stroke. In addition, thrombocytopenia is a common finding that leads to bleeding complications in patients with CCHD.
Complications
As noted above, complications of PAIVS include the following:
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CHF
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Sudden death
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Arrhythmia
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Cyanosis
Patient Education
Provide cardiopulmonary resuscitation (CPR) instruction to family members.
Educate family members about congenital heart disease (CHD).
Consider fetal echocardiography and genetics counseling for future pregnancies. [6]
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The heart catheterization.
