SIMPLIFIED METHOD FOR CALCULATING AORTIC-VALVE RESISTANCE - CORRELATION WITH VALVE AREA AND STANDARD FORMULA

Aortic valve resistance (AVR) is a useful index to assess the severity of aortic stenosis. This study compared the standard method to calcul ate AVR with a simplified method based on the conventional approach fo r measuring vascular resistance: AVR = (peak-to-peak transaortic press ure gradient/(cardiac output2.5))*80, where 80 is a conversion factor and 2.5 assumes that the systolic ejection period comprises 40% of th e R-R cycle. We compared the standard AVR, the simplified AVR, and the Gorlin-derived value area in 118 patients with pure or dominant aorti c stenosis. There was a strong linear correlation between the standard and simplified AVR (r = 0.96, p < .0001). There was a curvilinear rel ation between the aortic valve area and AVR (r = 0.92, p < .001). In 4 8 patients with aortic valve area greater-than-or-equal-to-0.7 cm2, th e AVR was <300 dynes-sec-cm-5 in 45 patients (94%) by the standard met hod and in 42 patients (88%) by the simplified method (p = NS). In con clusion, our method for measuring AVR is accurate and simpler than the standard method. (C) 1993 Wiley-Liss, Inc.