Die extravasale Komponente des Coronarwiderstandes mit steigendem linksventrikulären Druck.

In experiments on anaesthetized dogs the arterial blood pressure and the left ventricular pressure were enhanced by intraarterial blood transfusion. The circumflex branch of the left coronary artery was perfused by constant blood pressure at 65, 100 or 200 mm Hg. After elimination of the sinus node the heart rate was kept constant at 150 beats per minute by electrical stimulation of the right auricle. The metabolically regulated component of coronary resistance of the circumflex branch was kept constant by a maximal pharmacological dilatation. On this condition the coronary blood flow decreases with increasing left intraventricular systolic pressure. The coronary resistance increases. The increasing coronary resistance with increasing intraventricular blood pressure is caused by an enhancement of the extravascular component because the perfusion pressure and hematocrit were constant, and the coronary vessel maximal dilated. The rise of coronary resistance with increasing intraventricular blood pressure depends on the height of perfusion pressure. Low perfusion pressure is combined with a marked increase, while the increase is small in the experiments with high perfusion pressure. The pathophysiological significance of the results has been discussed. [ABSTRACT FROM AUTHOR]