Stafford I. Cohen

Adverse reactions to quinidine in hospitalized patients: findings based on data from the Boston Collaborative Drug Surveillance Program.

This study systematically analyzed the incidence and variety of adverse reactions to quinidine sulfate in 652 consecutively monitored hospitalized patients. Fourteen percent of the patients sustained adverse reactions of sufficient severity to warrant discontinuation of the drug. These reactions include GI intolerance, cardiac arrhythmias, fever with and without associated hepatic dysfunction or leukopenia, cinchonism, and hemolytic anemia. Cardiac arrhythmias were infrequent and, when present, generally occurred within 3 days of institution of quinidine therapy. There were no quinidine-related fatalities in this study group.

Infra-His Bundle Origin of Bidirectional Tachycardia

A case of bidirectional tachycardia is presented in a patient with cardiomyopathy, pulmonary emboli, and digitalis toxicity. The arrhythmia has usually been considered ventricular in origin. A supraventricular origin has also been suggested. Simultaneous recordings of standard electrocardiographic leads and His bundle potentials demonstrated that the abnormal rhythm originated in the left ventricle and indeed was a bidirectional ventricular tachycardia. Enhanced phase 4 depolarization in the divisions of the left bundle branch is advanced as a theoretic underlying mechanism in some instances of this arrhythmia.

Pulsus paradoxus and Kussmaul's sign in massive pulmonary embolism

Angiographically proved pulmonary embolic disease was associated with abnormal venous or arterial pressure responses, or both, to inspiration in three patients. The abnormal responses were evident clinically as paradoxical inspiratory filling of the cervical veins (Kussmauls sign) or an exaggerated decrease in systemic blood pressure during inspiration (pulsus paradoxus). The hemodynamic abnormalities documented at the time of cardiac catheterization occurred in the setting of multiple acute pulmonary emboli, pulmonary hypertension and underlying cardiac disease. Pulmonary embolism should be considered in the differential diagnosis of pulsus paradoxus and Kussmauls sign.Abstract A case is presented which emphasizes the fact that two classical signs of pericardial tamponade, pulsus paradoxus and inspiratory distension of the neck veins, may both be prominent physical signs of massive pulmonary embolism. Possible mechanisms for these signs in this setting are suggested.

Catheter-induced arrhythmias

Abstract Catheter-induced arrhythmias, which occurred several hours to several days following successful placement of temporary transvenous right ventricular electrodes or flow-directed pulmonary artery catheters were observed in six out of 106 patients. The arrhythmias took the form of ventricular bigeminy, ventricular tachycardia and, in one instance, isorhythmic dissociation. These arrhythmias were resistant to high doses of antiarrhythmic medication. The diagnosis can be suspected by noticing an excessive catheter loop or an altered catheter position in the chest x-ray or by observing faulty sensing, erratic pacing, or an increased threshold for ventricular stimulation. Corroborative evidence can be obtained from the electrocardiogram, where the catheter-induced depolarizations usually take a left bundle branch block pattern and the coupling interval of the ectopic beats may vary widely. Some pacing catheter-induced beats resemble the paced beats in configuration. In other cases, the rhythm cannot be explained by established principles. The diagnosis of catheter-induced arrhythmia is confirmed when the arrhythmia ceases following removal or repositioning of the catheter.

Supraventricular Origin of Bidirectional Tachycardia Report of a Case

We have confirmed a supraventricular origin of bidirectional tachycardia with simultaneous standard electrocardiograms and a His bundle electrogram. The patient had sinus rhythm, variable trifascicular block and atrioventricular block below the His bundle. Ventricular excitation varied among three patterns which included right bundle branch block with right axis deviation (RBBB-RAD), right bundle branch block with left axis deviation (RBBB-LAD), and right axis deviation without right bundle branch block (RAD). Sinus beats with alternating patterns of RBBB-RAD and RBBB-LAD resulted in bidirectional tachycardia as did sinus beats with alternating patterns of RBBB-LAD and RAD. Our observations prove that bidirectional tachycardia may be initiated by a supraventricular pacemaker and that the distinguishing bidirectional quality of this arrhythmia need not always occur with constant right bundle branch block.

Concealed Retrograde Conduction in Complete Atrioventricular Block

Atrio-ventricular (A-V) conduction and retrograde concealed conduction were assessed in 13 patients with complete heart block distal to the His bundle. Antegrade conduction was defined by His bundle study. The presence or absence of retrograde concealed conduction of the atrio-ventricular node was determined during ventricular pacing. Four instances of retrograde concealed conduction of the A-V node were observed.

Competitive rhythms with synchronous standby (demand) pacemakers

Abstract Two cases are presented which illustrate some limitations of synchronous standby (demand) pacemakers in preventing competitive rhythms. The possibility of a pacemaker stimulus firing in the vulnerable period of a competitive beat is diminished but not precluded by the choice of a synchronous demand pacemaker.

Flow murmur associated with partial occlusion of the right pulmonary artery

An 18-year-old male student presented with a brief history of syncope followed by shortness of breath with exertion, and the development of murmur over the right chest. The symptoms and murmurs were related to a pulmonary embolus which partially occluded the right pulmonary artery and its major branches. The murmur gradually diminished and disappeared when right pulmonary perfusion had almost returned to normal as determined by lung scan. The association of pulmonic flow murmurs and pulmonary emboli is reviewed.

Disappearance of bundle branch block with slowing of normal heart rate

Abstract Four patients are presented with varied mechanisms of converting bundle branch block to normal ventricular conduction with slowing of normal heart rate. One patient had a relatively constant range of critical heart rates for left bundle branch block, incomplete left bundle branch block, and normal conduction during a three-year period of observation. This report emphasized that bradycardia-dependent normalization of bundle branch block is not uncommon.