Pulmonary atresia with intact ventricular septum (PA-IVS) is a rare congenital heart disease, comprising less than 1% of all congenital heart defects globally. It is defined by complete blockage of the right ventricular outflow tract without a ventricular septal defect, commonly accompanied by underdevelopment of the right ventricle and tricuspid valve. This condition exhibits substantial variability in clinical presentation and outcomes, primarily driven by the degree of right ventricular and tricuspid valve hypoplasia, as well as the presence of right ventricle-dependent coronary circulation.
The pathophysiology of PA-IVS involves complete blockage of the pulmonary valve, resulting in obstruction of the right ventricular outflow tract. This commonly leads to an underdeveloped right ventricle, and the elevated intraventricular pressures can promote the formation of abnormal coronary artery connections, known as right ventricle-dependent coronary circulation. These alternative coronary pathways provide a means for decompressing the hypertensive right ventricle, but they are associated with unfavorable outcomes due to progressive stenosis, which can contribute to myocardial ischemia and reduced myocardial perfusion.
Pulmonary atresia with intact septum. From: Centers for Disease Control and Prevention. (2024, October 21). About Pulmonary Atresia. https://www.cdc.gov/heart-defects/about/pulmonary-atresia.html
Newborns affected by PA-IVS typically exhibit cyanosis shortly after birth, especially following the closure of the patent ductus arteriosus, which is crucial for sustaining pulmonary circulation in these patients. Physical examination often reveals a single heart sound, a pansystolic murmur if tricuspid regurgitation is present and potentially a murmur associated with a patent ductus arteriosus. The primary diagnostic assessment is performed via echocardiography, which can identify the abnormality in up to 86% of cases prenatally. However, a comprehensive evaluation of the coronary circulation necessitates cardiac catheterization, given the frequent presence of right ventricle-dependent coronary circulation in these individuals.
The management of PA-IVS is highly individualized, relying heavily on the characteristics of the right ventricle, tricuspid valve and coronary anatomy. Initial treatment commonly commences with the administration of prostaglandins to maintain ductus arteriosus patency, which is crucial for survival prior to definitive surgical or catheter-based intervention. Possible interventional approaches span a range, including systemic-to-pulmonary shunts, right ventricular decompression, biventricular repair, single-ventricle palliation and even heart transplantation in severe cases.
Recent advancements in fetal cardiac interventions have emerged as a promising therapeutic option, enabling in utero valvuloplasty procedures to support right ventricular development and enhance the potential for achieving biventricular circulation. However, these interventions are complex, necessitating substantial expertise and their outcomes remain under active investigation and evaluation.
The long-term prognosis for individuals with PA-IVS is influenced by multiple factors, including the type of surgical intervention and the presence of coronary abnormalities. Over time, survival rates for individuals with PA-IVS have improved significantly, largely due to advancements in neonatal care, surgical techniques, and postoperative management. Nevertheless, mortality remains high during the neonatal and interstage periods, particularly for patients with complex coronary anatomy or those necessitating multiple interventions. Furthermore, PA-IVS patients who reach adulthood frequently face ongoing risks associated with myocardial ischemia stemming from right ventricular dependent coronary circulation, potentially requiring additional interventions.
Genetic research has provided valuable insights into the underlying causes of PA-IVS. While the specific genetic mechanisms remain elusive, studies suggest a strong hereditary component for right ventricular outflow tract obstruction and related congenital heart defects. Continued investigations into the molecular processes governing cardiac development could uncover novel therapeutic avenues and help optimize management approaches for individuals with PA-IVS.
Comprehensive interprofessional teams are crucial to enhancing outcomes for patients with PA-IVS. Advancements in prenatal diagnosis, the prospect of fetal interventions, and the ongoing development of tailored management approaches hold promise for further reducing mortality and improving quality of life for this patient population.
PA-IVS is one of the most complex congenital heart conditions. Its intricate anatomy, variable clinical presentation, and significant long-term issues make it exceptionally challenging to manage. Nonetheless, medical advancements in surgery, catheter-based treatments and fetal cardiac procedures have improved survival rates for these patients. Still, substantial challenges persist, especially in addressing right ventricular-dependent coronary circulation and other right ventricular complications. A comprehensive, personalized approach incorporating early diagnosis, customized interventions, and ongoing collaboration among healthcare professionals is crucial to optimizing outcomes and quality of life for individuals with PA-IVS.
