In vivo estimation of left ventricular wall volume in volume-overloaded canine hearts

Abstract

Several geometric algorithms have been applied to estimate left ventricular wall volume (Vwall) from two-dimensional echocardiograms but have not been validated in eccentrically hypertrophied hearts. These algorithms can be fitted to the general formula: Vwall = k.Ao.Lo = k.Ai.Li, where Ao and Ai are the outer (epicardial) and inner (endocardial) short-axis areas, Lo and Li are the corresponding long-axis lengths, and k is a constant. The simplifying assumption that Lo and Li are equal yields Vwall = k.Awall.Lo, where Awall = Ao - Ai. In 20 unsedated dogs (10–30 kg), including 10 with aortic regurgitation of 1–18 wk duration, the relationship between actual Vwall (determined postmortem) and Awall.Lo was not significantly different from the line of identity (Vwall = 1.01 Awall.Lo + 0.5 ml, r = 0.98, SEE = 3.5 ml), indicating k was not significantly different from 1. There was no significant difference between predicted and actual Vwall over a range of 31–105 ml, and interobserver variability was 4.1%. The simple area-length product, Awall.Lo, accurately predicts Vwall of both normal and volume-overloaded hypertrophied canine left ventricles and is thus suitable for serial observations of hypertrophic adaptation to volume overload.