Changes in left ventricular dimensions and performance resulting from acute and chronic volume overload in the conscious dog.

A previously described animal model with an aorta to left atrium shunt has been modified to assess changes in left ventricular dimensions and performance resulting from volume overload of the left ventricle and to determine if any of these changes can predict outcome. In eight surviving dogs, end-diastolic and end-systolic diameters and estimated stroke volume increased rapidly in a curvilinear fashion over approximately 60 days with no significant changes thereafter. Mean normalized circumferential fibre shortening velocity was slightly less than and fractional shortening was similar to the controls; the changes in both indices were parallel to those in the controls. In five dogs that died 5-18 days postoperatively in congestive heart failure, none of the measurements obtained could be used to predict the outcome; the changes in the left ventricular diameters were similar to those in the survivors and systolic function was either normal or enhanced.