abnormal conotruncal ridge morphology conotruncal ridge hyperplasia conotruncal cushion hyperplasia outflow tract cushion hyperplasia 2010-10-05T02:26:55Z aortico-pulmonary spiral ridge hyperplasia csmith bulbar ridge hyperplasia MP:0010588 endocardial ridge hyperplasia MPheno.ontology overdevelopment or increased size of the pair of spiral mesenchymal swellings in the primordial ventricular outflow tract, that eventually fuse to form the conotruncal septum, dividing the subvalvular outflow tract and contributing to the membranous interventricular septum