<prompt> The most common cardiac congenital malformations seen clinically isPersistent truncus aeriosusMembranous VSDCommon ventricleForamen secundum defect  <response>: The most common of all cardiac congenital malformations seen clinically are membranous VSDs. The membranous interventricular septum forms by the proliferation and fusion of tissue from three different sources: Right bulbar ridge Left bulbar ridges Atrioventricular AV cushions. Because of this complex formation, the probability of defects is very high. 