[Characteristics of the aortic rheogram (an experimental study)]

The authors aim to describe aortic rheogram and examine its changes under the influence of some agents, to compare with the phases of the heart activity and to explain the origin of the curve. They use experimental animals (cats), to whom aortic rheogram is recorded by means of a probe-electrode, as well as atreiral blood pressure, phonocardiogram and electrocardiogram. The changes in the aortic rheogram are recorded after elevation or diminition of arterial blood pressure (medicamentous and mechanical), replacement of a part of the abdominal aorta with nonelastic prothesis and application of a model heart-aorta-vascular bed, in which the "systolic volume" is changeable as well as the "peripheral vascular resistance". The authors come to the conclusion that the aortic rheogram, recorded by a probe-electrode, is a reflection of the fluctuations in the volume velocity of the blood flow. Furthermore the general amplitude of the curve is in direct dependence of the systolic volume of the left ventricle. The peripheral vascular resistance and elasticity of the aortic wall do not affect substantially the form and amplitude of the rheogram. The value of the mean arterial blood pressure itself does not influence the form and the value of the curves.