Genesis of the Force Ballistocardiogram of the Dog

¹ From the Department of Medicine, Medical College of Alabama and the Medical Service of the Veterans Administration Hospital, Birmingham, Alabama

Force ballistocardiograms from the dog were obtained before, during and after pulmonary and aortic artery ligation. Ballistocardiographic waves persisted during the experimental conditions. By inflating with air balloons placed in the left and right ventricles, blood flow was interrupted and, in addition, the ventricles were stretched so that the force of ventricular contraction was increased. Again ballistocardiograms were obtained with forces occurring throughout the entire systolic period. The amplitude of the complexes obtained was roughly proportional to the degree of stretch or the amount of air put into the balloons within the ventricular cavities. The ballistocardiograph waves during cessation of blood flow were found to correspond to those noted during the control period. It is concluded that myocardial forces per se can be of significant magnitude and under certain circumstances can produce movements even greater than those noted during the normal hemodynamic state. It is further postulated that the ballistocardiogram represents a complex wave form made up of both right and left ventricular forces, in addition to blood flow in both the pulmonary and aortic arteries and that no single segment contains a monogenetic force.