The dynamics of the coronary venous pressure in the dog.

Abstract

The dynamics of the pressure in the great cardiac vein and coronary sinus was studied in 30 anaesthetized, artificially ventilated dogs. The pressure in the coronary venous system was found to be pulsatile and two positive pressure waves were distinguished. The a-wave, coinciding with the right atrial systole, appeared in the distal parts of the coronary sinus only, whereas the v-wave, concurring with the ventricular systole, was observed at all levels of the coronary venous system investigated, being most distinct in its proximal portions. The a-wave was accentuated during rapid atrial infusion which raised the right atrial pressure level. On the other hand, the v-wave was very markedly exaggerated following sympathetic stimulation and, particularly administration of norepinephrine (1 and 5 γ/kg i.v.), this concurring with the increase of ventricular contractile force. The amplitude of pressure pulsations rose, on the average, from 6.2–10.6 mm Hg following sympathetic stimulation, and from 7.7 to as much as 31 mm Hg with a 5 γ/kg dose of norepinephrine. The amplitude of pressure pulsations within the coronary sinus was also increased by papaverine (2.5 mg/kg i.v.) which elicited a marked augmentation of coronary blood flow without causing any significant rise of ventricular contractile force. The amplitude of pressure pulsations rose, on the average, from 8,8–13,7 mm Hg. Increasing the heart rate, over a range of 70 to 300 beats per minute, brought about a reduction of pulsations paralleling the reduction of ventricular contractile force despite the concomitant augmentation of coronary blood flow. It is concluded that the pulsations of the coronary venous pressure are due to mechanical effects of ventricular contractions mainly, which acting as a muscle-pump promote the emptying of the coronary veins. The actual amplitude of pressure pulsations is determined by the force of ventricular contractions, and by the state of filling of the coronary veins correlated with the level of coronary blood flow.