Stroke normalized pressure: a useful parameter for the analysis of left ventricular outflow obstruction

A new method of presenting the in vivo left ventricular pressure-flow data is developed in the present study. This separates left ventricle ejection into unrestricted, progressively restricted and severely restricted cases. This method uses ejection volume and time to define a normalizing 'stroke' pressure, which is successful in collapsing the large variability of in vivo data to a few curves with characteristic shapes, depending on the degree of obstruction. Hypertrophic cardiomyopathy is shown to fall into both unrestricted and progressively restricted categories. Normal hearts form the unrestricted case, while a severe aortic valvular stenosis is characteristic of the severely restricted case.