Subaortic Membrane and Patent Ductus Arteriosus in Rare Association-Case Series

BACKGROUND: The combination of subaortic membrane (SAM) and patent ductus arteriosus is very rare. Subaortic stenosis is the second most common form of left ventricular outflow tract (LVOT) obstruction after valvular aortic stenosis. We are reporting the largest case series of SAM and PDA. METHODS: We included all patients that were diagnosed with the combination of SAM and PDA at our cardiac center. We have reviewed patients echocardiographic studies, cardiac catheterizations, surgical notes and all the outpatients notes. RESULTS: We have a total of 7 patients. The age at presentation was in the early childhood with 3 patients diagnosed in infancy. Four patients had severe and moderate LVOT obstruction with SAM being very close to the aortic valve and all required surgical intervention. The last three patients had mild LVOT obstruction 2 of them with the SAM being > 4mm away from the aortic valve. Six out of the seven patients had intervention while the last one is under clinical follow up currently. PDA closure did not change the outcome. There were no other postoperative complication like developing new AI or developing complete heart block. There was no relation between gender, height, weight or age at diagnosis to the SAM clinical course. CONCLUSION: SAM and PDA association is very rare. The underlying pathophysiology is not well understood. When the SAM is closer to aortic valve (≤ 4mm), it carries higher risk of progressive LVOT obstruction. The interventions for SAM and PDA were safe procedures.