Robert F. Gomprecht

Antiarrhythmic Prophylaxis with Phentolamine In Acute Myocardial Infarction

T HE reduction in mortality after amm acute myocardial infarction has been largely due to the prompt and effective treatment of ventricular tacimyarrhythmias in coronary care units.’ In recent years thme enmphasis has changed from the treatmemut to the prevention of such arrhmythmias,2 as a result of the observations that imi many patients the detection of such arrimythmmias and the initiation of emergency therapy may be commsiderably delayed. Even iii coronary care units, serious hemodynamic disturbances may occur in the period between the appearance and time eorection of a major arrhythmia. Emergency therapy may have undesirable effects on time patient, and correction of an established arrhythmia is often difficult and at times impossible.3-4 Further, ventricular fibrillation is not almvays preceded by premonitory arrimythrnias, or time warning may be too brief to permit prevemmtive therapy.7 In imis experimental work on dogs, Leimdorfer8-9 shomved that the intravenous administration of phentolamine prevented nicotine sulfateand epinephrine-induced arrhythmias and converted methacholineinduced atrial flutter, fibrillation, and atrioventricuhar nodal rhythm to normal sinus rhythm. He further demoimstrated that pimentolanuine administration prevented the appearance of pronounced

Unusual Electrocardiographic Manifestations of Hypocalcemia

From the Department of Medicine Misericordia-Fordham Hospital Affiliation, Bronx, N.Y. and New York Medical College, New York City. Changes in the human electrocardiogram with hypocalcemia have been described by many investigators. The most constant and outstanding change described is abnormal prolongation of the QT interval. 1-3 Abnormalities of the T waves have also been described, but these changes are variable in appearance.4-6 Marked abnormalities of the QRS complexes and the ST segments have never been described in the hypocalcemic state. The present report describes QRS and ST segment change simulating an acute myocardial infarction with

Ventricular aneurysm in primary myocardial disease.

From the Department of Medicine. Misericordia and Fordham Hospital Affiliation, Bronx, New York and New York Medical College, New York, New York. Aneurysm of the left ventricle is usually due to myocardial infarction. It has been recognized that this complication can occur in 24 to 35% of patients with coronary artery disease, 2. Rarely ventricular aneurysms can occur as a result of congenital defects, trauma, myocardial abscess or ulcerating bacterial endocarditis. However, it is not well recognized that ventricular aneurysms can also occur in patients with primary myocardial disease. Further, they are a frequent occurrence in this condition-.

The Effect of Pharmacologic Doses of Steroids on Atrioventricular Conduction in Man

His bundle electrograms were performed in ten patients with organic heart disease. Recordings were made at various rates using right atrial pacing. Two grams of methylprednisolone were infused intravenously over a 20-minute period. The PI-A, A-H, H-Q, and H-S intervals were obtained before and up to 1 hour after the infusion of the steroid. The maximum effect was seen at 1 hour. All patients showed a significant prolongation in the A-H interval with negligible effects on other intervals. At the atrial pacing rate of 120 beats/minute, the average A-H interval increased from control of 119 milliseconds to 159 milliseconds after steroids (P smaller than 0.01). Second-degree heart block occurred at lower pacing rates after steroids in six patients as compared with the control state. The postsuppressive sinoatrial node recovery time was increased in seven cases after steroid infusion. Pharmacologic doses of steroids can impair conduction through the atrioventricular node.

The Effect of Phentolamine On Conduction in the Bundle of His

A His bundle electrogram was obtained in a 65 year old male with syncopal episodes. A split bundle of His deflection was recorded. After the intravenous administration of phentolamine, a marked shortening of the H-H interval was observed. This signifies an improvement in conduction at the bundle of His level.

The Effects of Chronic Ventricular Pacing On the Human Conduction System

Six cardiac patients had His bundle electrograms obtained prior to ventricular pacing. Hours to days after constant pacing, repeat His bundle electrograms were obtained. The H-Q interval increased after pacing in 5 of the 6 patients. The average H-Q interval of 55.8 msec increased to the post pacing value of 67.5 msec (p smaller 0.02). Thus ventricular pacing can produce a conduction delay in the His Purkinje system.

The Effects of Reserpine On Atrioventricular Conduction in Man

Since sympathomimetic amines speed AV conduction,’ a reserpine induced depletion of cardiac norepinephrine would be expected to slow AV conduction. Cohen and his co-workers3 subsequently observed that the long term oral administration of reserpine resulted in an increase in the PR interval in 8 patients subjected to atrial pacing at rates of 80 to 150 beats/minute. However this investigation was performed before the introduction of His bundle electrograms, and the effects of intravenously administered reserpine were not evaluated. In the present study, reserpine was administered intravenously to fourteen patients. Electrocardiograms and bundle of His electrograms were recorded before and after the administration of the drug. The effects on both atrioventricular and intraventricular conduction were determined.

Cardiac Effects of Insulin, Glucose, and Potassium

Glucose-insulin-potassium (G.I.P.) infusions have been recommended as a useful adjunct to the management of severe congestive heart failure. Ten patients with cardiac disease underwent a diagnostic cardiac catheterization. Pressures and cardiac output were obtained prior to and immediately after the 10 minute infusion of a mixture containing 50 grams of glucose, 10 mEq of potassium and 20 units of insulin. (Table: see text). G.I.P. infusions can increase the cardiac index. This is due to a combined effect of volume expansion and catecholamine stimulation.

His Bundle Electrograms and Atrial Flutter With 4:1 Av Conduction

From the Department of Medicine, Misericordia-Fordham Hospital Affiliation, Bronx, N. Y. and New York Medical College, New York City. The diagnosis of atrial flutter is usually clearly established by the electrocardiogram. The characteristic atrial oscillations occur regularly, at an average rate of 300 per minute. The ventricular rate is usually 150 beats per minutes with a 2:1 AV conduction ratio.

First degree A-V block due to a triple block in the A-V conduction system.

The routine electrocardiagram can detect lengthening of the PR interval with a resultant diagnosis of first degree A-V block. However the exact site of the delay or block can not be localized by this technique. Further the PR interval represents the transmission time through the (1) atrium, (2) A-V node, (3) bundle of His and (4) bundle branches and Purkinje network. The recent introduction of the His bundle recordings have demonstrated that delays or block in conduction can actually occur in these 4 regions of the A-V conduction system.’ , It is theoretically possible to have blocks at multiple sites which can not be recognized on the surface electrocardiogram. This report will demonstrate that a triple block in the conduction system can occur in a patient with a prolonged PR interval and a normal QRS interval.