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 calculate AVR with a simplified method based on the conventional approach for measuring vascular resistance: AVR = (peak-to-peak transaortic pressure gradient/(cardiac output*2.5))*80, where 80 is a conversion factor and 2.5 assumes that the systolic ejection period comprises 40% of the R-R cycle. We compared the standard AVR, the simplified AVR, and the Gorlin-derived value area in 118 patients with pure or dominant aortic stenosis. There was a strong linear correlation between the standard and simplified AVR (r = 0.96, p < .0001). There was a curvilinear relation between the aortic valve area and AVR (r = 0.92, p < .001). In 48 patients with aortic valve area > or = 0.7 cm2, the AVR was < 300 dynes-sec-cm-5 in 45 patients (94%) by the standard method and in 42 patients (88%) by the simplified method (p = NS). In conclusion, our method for measuring AVR is accurate and simpler than the standard method.