Some physical aspects in cardiovascular dynamics

William Harvey (1628) emphasized that comparative physiologic studies enabled him to understand the essence of blood circulation. This allometric hemodynamic hypothesis was tested: with growing mass the function changes. Cardiovascular dynamics in the whale, elephant, and hummingbird were compared. A custom made portable quantitative ballistocardiograph was constructed: the natural frequency was 1000 cps and it registered force when the examinee was in the sitting position. A special transistor amplifier with a long time constant reduces distortion of form, phase, and time of the registered curves, secured from the VHF-chair of 1000 Hz. No damping or isolation from building vibrations was necessary. Calibration is in absolute values (Newtons). The weight of the system is 5.5 kg. Characteristic quantities are systolic force (F) and minute cardiac force (MF = F x HR). Examined groups were healthy obese children, normal children, adult anorectics, and healthy normals. The minute cardiac force in obese boys was smaller, but not in girls. The systolic force per kg of body weight F kg(-1) in obese boys was smaller. F in anoretic women is lower, but not in men. MF did not differ in men and women; F kg(-1) is higher in anoretic men and women. The same is true for MF kg(-1). Additionally echocardiographic examinations were made in normal (12-14 years) and obese (12-15 years) boys: echo/Doppler data also showed differences indicating that compliance is lower in obese boys and the maximal flow velocity in the aorta in obese boys is lower. A close relationship exists between the body mass and various cardiovascular dynamics indices.