 effect aortic regurgit left ventricular perform direct determin aortic blood flow valv replac volum regurgit blood flow effect perform left ventricl assess oper 14 patient vari degre aortic regurgit instantan forward regurgit flow ascend aorta measur sine-wave electromagnet flowmet simultan left ventricular aortic pressur patient aortic regurgit associ stenosi 63 75 percent total forward stroke volum regurgit succeed diastol calcul regurgit orific area rang 0 13 0 44 cm replac aortic valv starr-edward prosthesi absenc regurgit flow prove patient record aortic blood flow close resembl patient normal aortic valv net forward blood flow increas averag 60 percent total left ventricular stroke volum fell 42 percent aortic pressur rose 29 percent pressur work left ventricl elev preoper patient averag 89 g-m stroke fell averag 34 g-m stroke valv replac kinet ventricular work high patient compris 10 percent total work replac 4 8 percent afterward observ patient aortic stenosi associ aortic regurgit rang sever 24 72 percent total forward stroke volum patient valv replac residu regurgit afterward net forward flow rose averag 49 percent kinet left ventricular work extrem high patient averag 26 percent total work preoper 13 percent valv replac group pressur work variabl oper studi describ provid definit concern effect aortic valv diseas left ventricular perform man document favor chang flow pressur left ventricular work follow aortic valv replac 