[Evaluation of the seriousness of aortic valve stenosis: calculation of the valvular area or peak? Reliability of Hakki's formula]

Abstract

The severity of aortic valve stenosis should be assessed by means of the calculation of the valvular area; on the other hand, the routine use of the Gorlin's formula for the aortic area is laborious and time consuming. Recently Hakki proposed a simplified formula (area = cardiac output/square root gradient) for the calculation of valvular areas. This method does not require the assessment of the systolic ejection time or the transvalvular flow; furthermore, the peak systolic gradient instead of the mean gradient may be entered into the formula. We have evaluated the reliability of this formula on 83 patients with aortic valve stenosis either pure or with absent to mild aortic incompetence (angiographically first degree maximum). Twenty-eight patients had isolated aortic stenosis, 55 had associated mitral stenosis and/or mitral or tricuspid regurgitation. Our results show a good correlation between the values of valvular areas obtained by Hakki's formula and those obtained by Gorlin's formula (r = 0.90 in the first group and r = 0.91 in the second group of patients). On the contrary we observed a poor relationship between the peak systolic gradient and the valvular area, with a considerable scatter of the data, especially for low values of peak systolic gradient. We therefore conclude that the assessment of the aortic valve stenosis must be based on the estimation of the valvular area; in our hands the Hakki's formula has proven to be easy and sufficiently reliable for routine diagnostic studies.