C.V. Ramana Reddy

Electrophysiologic Properties of Coffee in Man

There is no information on the effects of coffee on the human conduction system. His bundle electrograms were obtained in 12 patients before and 20 minutes after the ingestion of coffee containing 150 mg caffeine. Antegrade and retrograde refractory periods were obtained with the extrastimulus method. The effective and functional refractory period of the atrioventricular node decreased after coffee ingestion. This improvement in conduction is probably mediated by a release of catecholamines.

Aneurysms of the pulmonary arteries.

A case of bilateral pulmonary artery aneurysms is presented. Serial car diac catheterizations over an 8-year period showed remarkably little he modynamic change. Thus there may be a long period of clinical and hemodynamic stability in this condition.

T-wave changes with intermittent left bundle branch block.

A 70-year-old woman was found to have an intermittent left bundle branch block. When her electrocardiogram showed normal conduction, T-wave inversions in leads V1-V3 appeared. These alterations suggested an anteroseptal infarction. However, the patient was asymptomatic, and the serum enzymes, technetium 99m pyrophosphate scan, and the thalium 201 scan were all negative. Thus the LBBB itself can produce T-wave in versions in the right precordial leads during the normal conduction phase which may simulate an acute myocardial infarction.

Hemodynamic Effects of Morphine in Cardiac Disease

The hemodynamic effects of intravenous morphine were documented by right heart catheterization in six patients with an acute uncomplicated transmural myocardial infarction one to three days after the onset of symptoms. Intracardiac pressures, brachial artery pressure, and cardiac output were determined before and 15 minutes after the termination of the morphine infusion. Five milligrams morphine was given intravenously over a 10-minute period. The brachial artery pressure fell from a mean of 78 to a mean of 73 mm Hg (NS). As a result or morphine administration, the average cardiac index decreased from 2.68 to 2.31 liters/min-m2 (P is less than 0.05), and the stroke index decreased from 27 to 22 ml/beat-m2 (P is less than 0.05). Only small changes were observed in the intracardiac pressures.

Electrophysiologic Properties of Hydralazine in Man

There is considerable interest in selecting the proper drug to preserve the ischemic myocardium, or twilight zone, in a patient with a recent myocardial infarction, Vasodilator therapy with an infusion of nitroprusside1 or phentolamine2,3 has been shown to improve left ventricular function by reducing both preload and afterload. Sublingual nitroglycerin4 as well as an infusion of nitroglycerin5 can also alleviate left ventricular failure in patients with an acute myocardial infarction. Similarly, chronic congestive heart failure patients, irrespective of the etiology, improve hemodynam‐ically after an infusion of phentolamine,6,7 nitroprusside8 or hydralazine.9 Oral nitrates,10 phentolamine,11 and hydralazine12 have also been demonstrated to produce improvement in chronic heart failure patients. Recently data has become available on the effects of phentolamine.13 nitroglycerin14 and nitroprusside15 on cardiac conduction in man. However there is no information on the electrophysiological properties of hydralazine in man. The present study involving 12 human subjects was undertaken lo determine what effect iniravenously administered hydralazine has on the human conduction system.

Effect of Potassium Infusion on the Human Conduction System

His bundle electrograms were recorded in 12 patients before and after the intravenous administration of 5 mEq of potassium. Antegrade and retrograde refractory periods were determined with the extrastimulus technique. The AH interval was 84 ± 7 msec before and 89 ± 7 msec after potassium (P < 0.05). The AH interval at an atrial pacing rate of 140/minute was 129 ± 13 msec be fore and 143 ± 16 msec after potassium (P < 0.02). The effective refractory pe riod of the atrium was 264 ± 9 msec before and 280 ± 9 msec after potassium ( P < 0.001). Thus small amounts of potassium delay conduction at the atrial and AV nodal level.

Subclavian Vein Thrombosis Following Cardiac Pacemaker Implantation

For the past 15 years, permanent and temporary transvenous cardiac pacing has become not only an accepted but an indispensable and manypronged tool. It has been used extensively for the Adams-Stokes syndrome, and in patients experiencing symptomatic bradyarrhythmias with or without a myocardial infarction. Recently, electrical pacemakers have been used to overdrive life-threatening arrhythmias refractory to pharmacologic approaches. 1 Complications of transvenous pacing include electrode displacement, component failure, myocardial perforation, infection, bleeding, and pacemaker-induced arrhythmias.~ 2 Rarely, thrombi around the pacemaker electrode have proved to be a major clinical problem. Prozam and associates noted the development of a right atrial thrombus around a pacemaker electrode with subsequent death due to pulmonary embolization Similarly, Kaulbach and Krukonis described thrombosis in the superior vena cava around a pacemaker electrode with death due to pulmonary emboli.4 A cerebral dural venous sinus thrombosis following the implantation of a transvenous pacemaker via the right jugular vein has also been described.5 5

Electrophysiologic properties of morphine in man.

The study group consisted of 13 patients with organic heart disease. Table 1 summarizes their clinical features. All patients were informed of the nature of the study and granted their informed consent. They were studied in the supine position in a postabsorptive, nonsedated state. Electrode catheters were percutaneously introduced and fluoroscopically positioned in (1) the lateral wall of the right atrium near its junction with the superior vena cava to record from and stimulate the region of the high right atrium; (2) the tricuspid valve to record bundle of His and low atrial activity; and (3) the right ventricular apex for ventricular pacing. The intracardiac electrograms were recorded at a frequency of 40-500 cycles/sec on a DR-12 Electronics for Medicine recorder at a paper speed of 100 mm/sec. Simultane-

Fibroplastic parietal endocarditis with eosinophilia.

A 44-year-old woman with marked eosinophilia, leukocytosis, congestive heart failure, and the murmur of mitral stenosis had a restrictive type of pulse contour at cardiac catheterization. A right atrial angiogram revealed a huge right atrium, a small right ventricle, and a dilated contractile outflow tract consistent with the diagnosis of Loefflers endocarditis. A marked conduction delay at the atrial level was demonstrated by His bundle electrogram studies.

Multiple Conduction Delays within the His Bundle

His Bundle recordings in a 75‐year‐old male with complete heart block exhibited split His Bundle potentials with three components thus demonstrating multiple conduction delays within the bundle of His.