A continuous and quantitative analysis of the uneven distribution of coronary blood flow was accomplished in anesthetized open-chest dogs using the distribution function of the hydrogen (H2) clearance time constant. The distribution function was derived by analysing the H2 washout curves in the coronary sinus which were obtained by the H2 clearance method, using platinum electrodes placed in th...

The hypothesis that neurally mediated coronary vasodilation occurs as part of the carotid baroreceptor reflex was investigated. The left main coronary artery was cannulated and perfused at constant pressure (100 mm Hg) in closed-chest, chloralose-anesthetized dogs. The heart was paced at a constant rate between 60 and 70 beats/min after atrioventricular heart block. Propranolol (1 mg/kg) was gi...

A test for the existence of a diffusional shunt in the myocardium was performed in closed-chest, chloralose-anesthetized dogs. Coronary blood flow was varied from 0.21 to 1.17 ml/min per g with a roller pump via a stainless steel coronary perfusion cannula. Following intracoronary artery bolus indicator injection, the coronary sinus venous appearance times of hydrogen, plasma protein labeled wi...

We determined the effect of heart rate on the disposition of neurally released norepinephrine from the cardiac tissues in open-chest, anesthetized dogs with complete atrioventricular block. After injecting desipramine to block the neuronal uptake of norepinephrine, we stimulated the cardiac sympathetic nerves supramaximally for about 3 minutes at a mean frequency of 2.7 Hz. In one series of exp...

Cardiac magnetic resonance imaging (CMR) demonstrated a sinus of Valsalva aneurysm (SVA) with severe dilatation of the right coronary sinus in association with a congenital bicuspid aortic valve (BAV) and sub-aortic membrane. The SVA had not been apparent on echocardiography as the dilatation was outside standard echo image planes. On both CMR and echo, blood flow was eccentrically directed int...

The derivation of coronary sinus flow during increased pulmonary and right ventricular pressures was resubmitted to experimental study. The primary reduction and subsequent augmentation in coronary flow following pulmonary artery constriction and the persistence of a greater flow after release preclude the concept of a variable contribution via thebesian channels from the right ventricular cavi...

Effects of H1-receptor stimulation on coronary arterial diameter and coronary hemodynamics were examined in 11 patients with angiographically normal coronary arteries and without variant angina or resting angina. Selective H1-receptor stimulation was achieved by infusing histamine into the left coronary artery at a rate of 2.0 micrograms/min for 5 minutes after pretreatment with cimetidine (25 ...

To determine whether myoeardial uptake of Rb 80 can be used as a useful index of coronary plasma flow, the extraction of Rb S(i from arterial plasma during one passage through the myocardium of dogs was measured at varying rates of flow. At rates of flow which are encountered in man, changes in the rates of flow and uptake of isotope by the myocardium paralleled each other closely. Rb 86 uptake...

The relationship between the increase in catecholamine levels of the coronary sinus blood and the amplitude of various cardiac responses to adrenergic nerve stimulation was studied in anesthetized dogs. Plasma catecholamine levels in both coronary sinus and aortic blood were measured by a modification of the radiometric enzymatic assay for tissue catecholamines and were found to be 0.622 plus o...