Sucking action of the left ventricle: demonstration of a physiologic principle by a gunshot wound penetrating only the right side of the heart.

This report describes a man who died after a gunshot wound that entered the right atrium and exited from the right ventricle without entering the cardiac septa or the left side of the heart. At necropsy, the left atrial appendage was found to be inverted and invaginated into the mitral orifice. The invagination of the left atrial appendage is viewed as anatomic evidence that a negative left ventricular pressure was created as the left ventricular volume rapidly decreased as a result of right-sided cardiac exsanguination. Previously reported experiments in animals demonstrating the sucking (negative pressure) action of the left ventricle during ventricular diastole are summarized. The prerequisite for creation of a negative pressure in the ventricles during diastole is an extreme diminution in left ventricular volume, in this case as a result of right-sided cardiac bleeding. Only a vacuum effect of the left ventricle during diastole can explain the inversion and invagination of the left atrial appendage in this patient.