Left ventricular dimensions during hemorrhagic shock measured by biplane cinefluorography

The effects of hemorrhagic shock on left ventricular dimensions and volume were studied in 15 splenectomized dogs. A 42 ± 1% decrease in total blood volume caused arterial blood pressure to fall 60% (from 120 ± 5 to 48 ± 3 mmHg); the first derivative of left ventricular pressure at a developed pressure of 40 mmHg fell 54% (from 1,930 ± 94 to 905 ± 93 mmHg/s, P < 0.05). Cardiac output fell 76% due to a 73% decrease in stroke volume; heart rate was unchanged at the end of hemorrhage but increased 50% during 3 h of sustained shock (from 110 ± 6 to 166 ± 8 beats/min, P < 0.05). During hemorrhage the septal-lateral and the anterior-posterior end-diastolic dimensions fell to a greater extent (7.8 mm, -21% and 7.0 mm, -18%, respectively) than the apex-base dimension (2.3 mm, -3.3%, P < 0.05). As a result of these dimensional changes, left ventricular end-diastolic volume fell 39% (from 48 ± 2 to 28 ± 1 cm³, P < 0.01). End-systolic dimensions fell in the same proportion during hemorrhage, resulting in a 30% decrease in end-systolic volume (from 30 ± 2 to 21 ± 1 cm³, P < 0.05). After 120 min of sustained shock, all end-diastolic dimensions remained unchanged, but end- systolic dimensions and volume increased significantly from values measured at end hemorrhage (P < 0.05), causing ejection fraction and stroke volume to fall to a greater extent. This study confirms a pronounced reduction in the minor axes of the left ventricle during hemorrhagic shock with subsequent reduction in ventricular function.