subendocardial ischemia develops in hearts that are fibrillated during cardiopulmonary bypass when : ( 1 ) the normal ventricle is fibrillated with a sustained electrical stimulus , ( 2 ) the hypertrophied ventricle is allowed to fibrillate spontaneously , ( 3 ) the fibrillating heart becomes distended , or ( 4 ) the perfusion pressure is reduced to approximately 50 mm hg .
C0018827
ventricle
C0018787
heart