A new framework for echocardiographic assessment of left ventricular mechanics: Sensitivity to heart failure

A recent report describes an approach to ventricular mechanics that employs mean end-systolic fiber stress and an exact mathematical strain index base d on wall thickness referenced to myocardial mass. We used echocardiography and mean arterial pressures to determine the strain index and wall stress in (1) normal hearts from patients and swine, (2) swine with pacing-induced congestive heart failure, and (3) patients with dilated cardiomyopathy. Pi gs were also studied under afterload variation with phenylephrine. Paired v alues of stress and strain index from control hearts (both swine and human) were tightly clustered. Values from animals and patients with congestive h eart failure deviated from this cluster. Excellent separation (sensitivity 83%, specificity 94%) was displayed between control and paced pigs, despite confounding effects of varying afterload. We conclude that these variables display little change over a large range of normal cardiac mass, but devia te from this range during heart failure.