What are the hemodynamic and angiographic determinants of S3 and S4 gallop sounds in patients with primary myocardial disease?
S4 gallop is driven by ventricular hypertrophy and reduced compliance, while S3 gallop is driven by ventricular dilatation, reduced cardiac output, and elevated filling pressures.
Clinical, hemodynamic and angiographic correlates in 23 patients with primary myocardial disease and either atrial (S4) or ventricular (S3) gallop sounds differentiated the two groups. Those with S4 gallop had normal mean left atrial pressures, low amplitude "v" waves, small drop from "v" to "y", usually reduced v/y slope, prominent "a" kick, abnormal echocardiogram of mitral valve, nearly normal cardiac output and marked left ventricular hypertrophy. In contrast the S3 group had elevated mean left atrial pressures, tall "v" waves and large drop from "v" to "y", with increased v/y slope, no prominent "a" kick, rapid filling on the echocardiogram, reduced cardiac output and left ventricular cavitary dilatation. Atrial gallop sound can thus be explained by ventricular hypertrophy, causing reduced compliance and increased resistance to filling, with augmented atrial boost and gallop, whereas considerable ventricular dilatation, with reduced cardiac output, elevated filling pressure and augmented early filling may produce ventricular gallop.
Shah et al. (Thu,) studied this question.