The apex impulse in mitral stenosis: graphic explanation of the palpable movements at the cardiac apex

Simultaneously recorded phonocardiograms and apexcardiograms of 39 patients with mitral stenosis (MS) were retrospectively analyzed. A notch on the upstroke of the apexcardiogram coincidental with the first heart sound (S1) occurred in 18 (47%) of the patients. The notch ratio or vertical distance from the onset of the apical impulse to the notch ratio or vertical distance from the onset of the apical impulse to the notch as a percentage of the total upstroke was measured and compared with the mean mitral diastolic gradient obtained at cardiac catheterization. Statistical analysis showed a significant relation (r = 0.61; p less than 0.01) between notch ratio and the mean mitral diastolic gradient. This study reaffirms that the complex palpable movements at the cardiac apex, consisting of a "tap" representing S1 occurring perceptibly after the onset of the apex impulse itself, are a useful diagnostic sign of MS. Furthermore, a graphic measurement of the extent of delay of S1 with respect to the onset of the apical thrust can provide a rough measure of the severity of the valvular obstruction.