John B. Schwedel

Transvenous pacing: A seven-year review☆

Abstract The short-term and long-term results of transvenous catheter pacing in 110 patients have been presented. A discussion of techniques and the indications for transvenous pacing have been outlined. Transvenous pacing of the heart via right ventricular endocardial stimulation is simple, rapid, and safe. The complications of infection, breakage of conductive leads, malposition, and cardiac perforation have all become relatively uncommon with greater experience, and affect a smaller and decreasing number of patients. The approach offers a continued promise, particularly as improved material becomes available.

Heart block: A method for rapid determination of causes of pacing failure in artificial pacemaking systems☆

Abstract The causes of pacing failure in transvenous and implanted pacemaker systems have been reviewed, and a method for the rapid determination of the cause of failure has been described. In all instances of pacing failure in patients with bipolar pacemaker circuits, except when both wires to the heart were broken, pacing was restored without thoracotomy or replacement of the transvenous pacemaker catheter. In instances of pulse generator failure, the batteries or pulse generator were replaced. In cases of malposition, the catheter was repositioned. In cases of wire breaks or short circuits, a unipolar circuit was established; and in cases of increased impedance or threshold for myocardial stimulation, the output of the pulse generator was increased. The exact delineation of the defect in a malfunctioning pacemaker system markedly facilitated the rapidity and ease of restoration of pacing and minimized trauma to the patient. In the early phases of transvenous pacemaker development there was a high incidence of pacemaker failure in our series. In the last 60 cases with transvenous pacemakers, the incidence of pacemaker malfunction has been less than 20 per cent. In the 45 patients with implanted pacemakers there has been a 33 per cent incidence of pacemaker malfunction.

Energy consumption for cardiac stimulation as a function of pulse duration

Summary Studies were performed of the threshold of cardiac stimulation as a function of impulse duration in dogs, acutely, and in humans acutely and chronically. Impulse durations from 0.1 to 5.0 msec. were utilized. o 1. Myocardial impedance does not vary as a function of impulse duration, within the measured range. 2. Voltage needed at threshold falls progressively from the shortest to the longest impulse durations. 3. Current utilized falls progressively from shortest to longest impulse durations. 4. Energy consumed at thresholds, acute and chronic, is highest at short impulse durations, falls progressively to a minimum at impulse durations of 0.2 to 1.0 msec., then rises at longer impulse durations. 5. Total charge consumed remains low until impulse durations of 0.2 and 0.5 msec. are reached. With lengthening of impulse, total charge consumed rises. An impulse duration of 0.5 to 0.75 msec. is more economical for production of ventricular systole.

Chronic constrictive pericarditis and rheumatic heart disease.

Abstract 1. 1. In a series of eighteen cases of chronic constrictive pericarditis, five had coexisting rheumatic valvular disease and are reported in detail. 2. 2. If constrictive pericarditis is suspected in patients with heart disease who have an atypical course, more cases will be discovered. 3. 3. Cardiac enlargement, normal intensity of heart sounds, and normal cardiac pulsations are not rare in patients with constrictive pericarditis. 4. 4. The presence of definite rheumatic heart disease does not exclude the existence of associated chronic constrictive pericarditis although there is no evidence that the two conditions are causally related. 5. 5. It is of significance that in three of the five cases in which constrictive pericarditis was associated with rheumatic heart disease, there was a history of another etiologic factor which may have played a role in the development of the disease.

Electrokymographic studies of abnormal left ventricular pulsations

Abstract A study of the incidence of paradoxical pulsations, both fluoroscopic and electrokymographic, has been made in thirty-one cases of anterior wall infarction, in twenty-eight cases of posterior wall infarction, and in eleven cases of combined anterior and posterior infarctions. The types of paradoxical pulsations noted have been listed. The presence of paradoxical pulsations without myocardial infarction has been noted, together with mention of the possible aid that the electrokymograph may give in the diagnosis of myocardial infarction in the presence of left bundle branch block.

Interlobar effusions in patients with heart disease

Abstract Although interlobar fluid accumulation has a varied etiology, it is most frequently encountered in patients with heart disease. In this condition it may be the end-result of an inflammatory process or, more commonly, it may be the transudative type found in decompensated individuals. Interlobar effusions arising by transudation differ in no way from those in the free pleural cavity except in location. Some are walled off in the interlobar region by an adhesive pleurisy of the general pleural space; others merely enter the fissure as an extension from a hydrothorax. In the course of heart failure pleural reactions are very frequent, not only in the interlobar region but also in the free pleural space. Upon resorption, only scars or thickened pleura remain. Whenever such residua are found, it is reasonable to assume that the patient had either preexisting fluid (interlobar or otherwise) or chronic pulmonary stasis. Interlobar effusions and their pleural thickenings are not roentgenological freaks, but constitute an integral part in the history of chronic cardiac disease.

Electrokymographic studies of the relation between the electrical and mechanical events of the cardiac cycle in Wolff-Parkinson-White syndrome

Abstract In a study of fifteen cases of Wolff-Parkinson-White syndrome by simultaneously recording the electrokymograms of the ascending aorta and pulmonary artery together with an electrocardiogram in the right anterior oblique position, we have found mechanical asynchronism in only five cases but have found evidence of delay in ejection from both ventricles, regardless of the side of the bundle of Kent, in most instances.

Electrokymographic studies of the relationship between electrical and mechanical asynchronism in the cardiac cycle.

Abstract In a study of eighty-three cases of bundle branch block, two cases of complete heart block with idioventricular rhythm, and twenty-one ventricular premature beats in fourteen patients, the mechanical ejection events of the greater and lesser circulation were recorded simultaneously by electrokymograms of the ascending aorta and pulmonary artery. We failed to find mechanical ejection asynchronism accompanying the electrical asynchronism in about 70 per cent of the cases. We did, however, find evidence of delayed ejection from both ventricles in the majority of cases. Several possible explanations for our findings are discussed.

Implanted cardiac pacemakers: Motion factors producing lead breaks*

Summary The abdominal course is a frequent site of implanted pacemaker lead breaks. These result from an unanticipated degree of motion and angulation resulting from normal body activity. Adequate visualization requires cineroentgenographic study of the pacemaker, and as a result, modifications of lead design and operative placement are suggested.

Electrokymographic studies in aneurysm of the left ventricle

Abstract These cases showing paradoxical pulsation of the left ventricular contour on fluoroscopy and electrokymography have been presented. In two of these a definite ventricular aneurysm was apparent on x-ray examination. The electrokymographic criterion for a localized area of ventricular damage is the demonstration of systolic expansion or diastolic collapse.