Pulmonary Atresia with Intact Ventricular Septum Corey Bregman, M.D. Children’s Memorial Hospital Chicago, IL

Overview Accounts for fewer than 1% of all congenital heart defects However is one of the more common etiologies of cyanotic congenital heart disease Cause is unknown No predilection by sex, and many sources believe no genetic basis

Overview Defined by an imperforate pulmonary valve combined with an intact ventricular septum Both an interatrial defect and a systemic to pulmonary shunt are required for survival Though conceptually simple, there is vast morphologic variation of the right heart and coronary arteries Treatment is tailored to this variation

Anatomy of the Defect

Spectrum Well formed infundibulum, and the imperforate pulmonary valve will have three cusps with commissure fusion Diminutive right ventricle, a severely narrowed or atretic infundibulum, and a primitive valve

Spectrum and Timing Variation in timing of insult relates to the morphologic variations Insult probably occurs later than that of pulmonary atresia with VSD Note that the pulmonary trunk is almost always present

Path of Blood Flow Typically systemic blood travels through a true secundum ASD or a PFO Rarely there are reports of a coronary sinus to left atrium fenestration Systemic to pulmonary arterial circulation through left sided PDA Rarely there are reports of descending aorta branches to the PA and of bilateral PDA

Associated Anomalies Hypoplastic but hypertrophied right ventricle Right atrial dilatation Tricuspid valve is rarely normal Coronary artery anomalies Often see aortic valve stenosis

Tricuspid Valve Can see extreme stenosis to profound regurgitation Severe in 25% of cases and florid regurgitation may result in fetal demise Profound displacement, dysplastic leaflets, shortened chordae Patients with the largest right ventricle usually have severe tricuspid regurgitation Patients with most underdeveloped right ventricle usually have severe tricuspid stenosis

Some patients have features of or concomitant Ebstein’s anomaly Dilated tricuspid annulus Downward displacement of the septal and posterior leaflets

Coronary Artery Anomalies Only seen when right ventricular is thick walled high pressure chamber Anomalies specific to this condition include: Coronary artery stenosis Coronary artery interruption “Coronary-cameral fistula” which represents direct communication between the right ventricle and a coronary artery through endothelium lined sinusoid

Coronary-Cameral Fistula Sinusoidal channels provide blood to myocardium prior to development of the coronary arteries during cardiac development Thought to persist with elevated right ventricle pressure and may communicate with one or both coronary arteries

Coronary Anomalies Right ventricular pressure transferred to the coronary arteries Myointimal hyperplasia Distortion of architecture and endothelium Resultant stenosis and interruption These lesions are often close to the fistulas

Coronary Anomalies Diminutive right ventricle Communication to LAD coronary artery Arrow points to interruption with no filling of aortic root This artery is right ventricle dependent

Myointimal Hyperplasia

Presentation and Management Infants deteriorate within hours after birth becoming cyanotic and hypoxemic Have a single S2, tricuspid and PDA murmers Prostaglandin E to maintain ductus Metabolic acidosis is ominous and usually indicates hypoxic cell damage Long term management more complex Will typically evaluate with both echocardiography and angiography

Radiography Heart size ranges from only mildly enlarged to filling the entire chest cavity If pulmonary parenchyma is visible may see reduced vascular markings

Further Imaging Role for both Echocardiography and Angiography Echo is weak in identifying the ventriculocoronary connections Angio is warranted to evaluate for these and the status of the coronaries

Echocardiography Imperforate Pulmonary Valve

Angiography Thickened tricuspid vlve and regurgitation has caused severe right atrial enlargement Ventriculocoronary communication with multiple stenoses

Surgical Considerations Is the patient a candidate for biventricular or univentricular repair? Are there ventriculocoronary connections? How much of the coronary circulation is right ventricle dependent? Is there an infundibulum? Is there a main pulmonary trunk in continuity with the imperforate valve? Is the left ventricular function preserved?

Right Ventricular Outflow Reconstruction Will give biventricular circulation Small hypertrophic right ventricle may enlarge and adapt after reconstruction Methods include Pulmonary valvotomy Outflow tract patch Catheter perforation of pulmonary valve

Univentricular Repair Algorithm Majority or entirety of coronary circulation is right ventricle dependent Severe tricuspid regurgitation or Ebstein’s anomaly

Summary Conceptually simple – but varied morphologic presentation Pay attention to the status of the right ventricle, tricuspid valve, and coronary arteries Management is specifically tailored to morphology Patients will require frequent follow-up

Sources Allen, Hugh D. Moss & Adams’ Heart Disease in Infants, Children & Adolescents: Including the Fetus and Young Adults, 6th Edition. Lippincott Williams & Wilkins. (2001). Mavroudis, C.; Backer, C. Pediatric Cardiac Surgery, 3rd Edition. Mosby. (2003). Park, Myung K. Pediatric Cardiology for Practitioners, 4th Edition. Mosby. (2002).