Interpretation of the effects of propranolol on coronary reactive hyperaemia.

The effect of propranolol on the hyperaemic response after transient coronary arterial occlusion has been evaluated. The excess volume of blood delivered to the myocardium after an occlusion is diminished after propranolol in proportion to the reduced coronary blood flow. From the findings it is not necessary to postulate a change in the intrinsic mechanisms of reactive hyperaemia after propranolol has been given.

Effect of heart rate and stroke volume on gas mixing in dog lung.

In nine anesthetized and ventilated dogs heart block was induced at thoracotomy, a pacemaker was inserted, and an electromagnetic flow transducer was placed round the main pulmonary artery. The chest was then closed. Stroke volume (SV) was varied by changing central blood volume.

Does beta-blockade directly reduce myocardial oxygen consumption?

This paper describes a method for determining whether beta-blocking agents reduce myocardial oxygen consumption by a direct action on the myocardium in addition to that reduction produced by changes in cardiac mechanical function. Measurements of myocardial oxygen consumption were made in anaesthetized dogs . Changes in heart rate were produced by atropine and by ventricular pacing.

Vasodilator effects of sulfinpyrazone in dogs.

The hemodynamic effects of sulfinpyrazone were investigated in 12 anesthetized dogs. Bolus injections into a coronary artery (1--500 mg) and a femoral artery (10--300 mg) and intravenous infusions (10 and 20 mg/min up to 500 mg) were given. After intracoronary injection, coronary dilatation occurred for over 20 min without major changes in cardiac muscle function.

Coronary xeroradiography.

Xeroradiography is shown to be especially helpful in coronary arteriography. Comparatively low concentrations of contrast medium are sufficient to provide adequate diagnostic details in the image. Selection injection techniques yield exceptional resolution of small vessels.

Effect of respiration on venous return and stroke volume in cardiac tamponade.

Measurements have been made of pressure and blood velocity in venae cavae and aorta in a patient with severe cardiac tamponade in whom there was pulsus paradoxus. The characteristic pressure changes of pulsus paradoxus were associated with variations in peak blood velocity in the ascending aorta and stroke output. Maximum filling of the right side of the heart occurred during inspiration, and was associated in time with minimum left ventricular stroke volume.