Changes in aortic blood pressure and cardiac output curves as induced by stenosis of the descending thoracic aorta.
In 9 anaesthetized open chest rabbits cardiac output and aortic blood pressure were recorded. Cardiac output was obtained by means of an electromagnetic blood flow transducer placed around the ascending aorta. When a 10 sec stenosis of the descending thoracic aorta was produced, an increase of mean, systolic, diastolic and pulse pressure was observed above the stenosis, with a remarkable delay of the peak systolic pressure with respect to the peak velocity of ventricular ejection. Moreover, it is note worthy that during the stenosis the deceleration phase of the ventricular ejection showed a slackening which was responsible for a longer ejection time. Owing to such a longer ejection time, in 4 experiments stroke volume and cardiac output increased above the control in spite of a high aortic impedance. It is probably that the changes observed in the contour of the ventricular ejection curve, depend on modifications of the gradient between left ventricle and aortic blood pressure as well as on the combined effects of the Starling's law and of the afterload.
D000818:Animals; D001013:Aorta, Thoracic; D001024:Aortic Valve Stenosis / Q000503:physiopathology*; D001794:Blood Pressure; D002302:Cardiac Output; D011817:Rabbits; D014655:Vascular Resistance