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Biomedical subjects

S S Barold

Publications and source records attributed to S S Barold.

18 recordsLinked to original sources

Familial cardiac myxoma: emphasis on unusual clinical manifestations.

This report describes familial cardiac myxoma involving parent and child. The familial occurrence of this condition, previously reported in four other families, underscores the necessity of screening all direct members of the family by echocardiography once the diagnosis of cardiac myxoma is made. Each patient presented with unusual clinical manifestations. The father, who had a right atrial myxoma associated with an atrial septal defect and mitral valve prolapse, presented with findings highly suggestive of paradoxical embolism. The daughter, who had an infected right ventricular myxoma, was initially treated for valvular subacute bacterial endocarditis before the diagnosis was made.

Adult

The significance of the MB isoenzyme in patients with acute cardiovascular disease with a normal or borderline total CPK activity.

CPK MB isoenzymes were qualitatively identified using an electrophoresis method in 166 patients with acute cardiovascular disease during a six month period. Forty-three had total CPK activity in the normal or borderline range (0--75 U/Liter at the time the MB isoenzyme was first identified. Fifteen of these patients were diagnosed as having had a new acute myocardinal infarction (Group I) and another 15 as having had an old myocardial infarction (Group II). Diagnosis was based on electrocardiographic changes or autopsy findings. The remaining 13 patients were classified as "ischemic heart disease" (Group III) in the absence of strict electrocardiographic criteria or autopsy evidence of myocardial infarction. Nine of the 15 patients in Group I subsequently had elevations of their total CPK activity above 75 U/L. In contrast the total CPK activity of only one patient from Group II and Group III subsequently exceeded 75 U/liter. All 43 patients had evidence of cardiovascular disease. Our findings suggest that the detection of MB isoenzyme in the presence of a normal total CPK activity is a significant laboratory finding and is indicative of cardiac myofiber injury.

Acute Disease

Unusual electrocardiographic pattern during transvenous pacing from the middle cardiac vein.

This report documents the unusual occurrence of a left bundle branch block pattern of ventricular depolarization during permanent pacing from the middle cardiac vein. All previous reports of ventricular pacing from the middle cardiac vein have described a right bundle branch block pattern of ventricular activation (dominant R-waves in the right precordial leads), except in one case where both right and left bundle branch block patterns occurred at separate times. A high posterior infarct allowed early activation of the right ventricle from the middle cardiac vein. Undue reliance on the electrocardiogram may detract from the diagnosis of electrode malposition.

Aged

Inapparent double puncture of the femoral artery and vein. An important complication of temporary cardiac pacing by the transfemoral approach.

An important complication of temporary cardiac pacing by the transfemoral approach. This report describes three cases of inapparent double puncture of the femoral artery and vein as a complication of the transfemoral approach for temporary cardiac pacing. This complication may lead to the passage of a pacing catheter to the right ventricle by way of the femoral artery and vein and may remain undiagnosed until the rigid outer sheath of the introducer set is withdrawn over the pacing catheter. Therefore, we recommend immediate withdrawal of the rigid outer sheath as soon as the catheter lies freely in the iliac vein or the inferior vena cava. If double puncture has occurred, arterial blood will leak around the pacing catheter. Control of arterial bleeding by local compression should not be attempted without removal of the pacing catheter.

Cardiac Pacing, Artificial

The noise sampling period: a new cause of apparent sensing malfunction of demand pacemakers.

Two patients with Omni-Stanicor pulse generators presented an apparent sensing problem characterized by intermittent reversion to fixed-rate pacing only during atrial fibrillation with a very rapid ventricular rate. Every fixed-rate cycle contained two unsensed beats. The first unsensed beat fell in the noise sampling period (the last 1/6 of the pacemaker refractory period) and, therefore, disabled the demand function of the pulse generator for a single timing cycle. The presence of two consecutively unsensed beats within one timing cycle (automatic or escape interval) during tachycardia suggests normal function of the noise sampling period of this particular pulse generator, rather than a true sensing problem. The diagnosis becomes evident if the sensing problem disappears when abbreviation of the refractory period occurs by reprogramming the pulse generator at a higher rate.

Aged

Unusual complication of bifascicular block during surgery under general anesthesia.

This report describes the occurrence of Mobitz type II AV block during surgery under general anesthesia in a patient with apparently uncomplicated right bundle branch and left anterior fascicular block (RBBB and LAH). Although prophylactic pacing is not usually recommended in uncomplicated RBBB and LAH, the events in this case suggest that this abnormality may not always be benign during surgery. Continuous monitoring is essential and emergency equipment for temporary pacing should be readily available near the operating and recovery rooms.

Aged

Periodic pacemaker spike attenuation with preservation of capture: an unusual electrocardiographic manifestation of partial pacing electrode fracture.

This report describes the electrocardiograms of a patient with an intermittent electrode fracture presenting with periodic attenuation of the pacemaker spike without loss of ventricular capture. There was infrequent prolongation of the spike-to-spike interval probably because the pulse generator interpreted random false signals as interference and reverted to its fixed-rate mode. These observations add to the spectrum of electrocardiographic abnormalities of electrode malfunction.

Aged

Reprogramming of implanted pacemaker following external defibrillation.

This report describes reprogramming of a pulse generator consequent to cardiac defibrillation. Analysis of the explanted pulse generator revealed normal function. We tested the electrical properties of several defibrillators and our studies suggest that erratic electrostatic discharges at the time of paddle application before defibrillation may create a signal sequence capable of reprogramming the particular pulse generator by activating either the reed switch or internal electronics.

Electric Countershock

Echocardiographic evaluation of intracardiac pacing catheters: M-mode and two-dimensional studies.

Thirty patients with right ventricular (RV) and 15 with coronary sinus (CS) pacing catheters were studied by M-mode echocardiography. RV catheters, detected in 23, appeared as linear echoes in the right ventricle during mitral valve recordings in 12, adjacent or superimposed on the tricuspid valve (TV) in 14, and immediately anterior to aortic root and pulmonary valve echoes in two with a redundant loop in RV outflow. In three with complete heart block, prominent systolic anterior movements of the TV occurred when atrial systole coincided with ventricular systole, probably due to catheter-induced TV "buckling" or exaggerated TV annular motion. Catheter echoes mimicked TV recordings in three, since its motion pattern was similar, although delayed and mimicked prolapsing right atrial myxomas in two because of multilayered complexes behind TV, while reverberations cluttering the left ventricle simulated structural echoes present in that cavity. CS catheters, detected in 14 as linear echoes in the area of atrial septum recorded behind the TV, showed typical small humps in late diastole/early systole. Cross-sectional echocardiography with a mechanical sector scanner demonstrated RV catheters at the RV apex in five of seven patients, while CS catheters were detected near the base of the atrial septum in three of five patients. Echocardiography has the potential to localize pacing catheters which are occasionally difficult radiologically or electrocardiographically. Failure to recognize catheter echo patterns may result in errors in echocardiographic interpretation.

Cardiac Pacing, Artificial

Intermittent tachycardia-dependent combined right bundle branch and left anterior conduction block.

A patient is described who had intermittent tachycardia-dependent combined right bundle branch and left anterior conduction block (left axis deviation) with simultaneous onset and disappearance during observations extending over 15 months. Although the site of conduction block could not be definitely determined the pathologic and electrophysiologic data suggest that there was a lesion in the distal part of the His bundle, presumably in fibers already arranged and predestined to supply the right bundle branch and left anterior areas. A single lesion at the so-called pseudobifurcation or two separate lesions with similar electrophysiologic consequences could also account for the observations.

Aged

Mechanisms of atrioventricular junctional tachycardia. Role of reentry and concealed accessory bypass tracts.

Electrophysiologic investigations with programmed stimulation of the human heart have clearly established the participation of the atrioventricular (A-V) junction in three different types of junctional reciprocating tachycardia: (1) paroxysmal supraventricular tachycardia in the Wolff-Parkinson-White syndrome: (2) the vast proportion of "paroxysmal atrial tachycardia" without evidence of preexcitation during sinus rhythm with antegrade conduction; and (3) the permanent or almost permanent (chronic relapsing) form of supraventricular tachycardia with its characteristic rate-dependent initiating mechanism. The obvious presence of the Wolff-Parkinson-White syndrome during sinus rhythm does not necessarily imply that the accessory pathway will be utilized during supraventricular tachycardia. Conversely, in the absence of preexcitation, the mechanism of A-V junctional reciprocating tachycardia has been traditionally attributed to pure intranodal dissociation, often without definite direct proof. Concealed accessory pathways (with unidirectional block) may be more frequent than realized and should be carefully searched for. Proof that supraventricular tachycardia utilizes an accessory pathway for retrograde conduction to the atrium often requires meticulous electrophysiologic studies- Conslucions based on the absence of various findings may be misleading. Emphasis must be placed on positive viagnostic features. One or more of the following observations may prove or disprove participation of a Kent bundle during supraventricular tachycardia: (1) induction of A-V block during tachycardia: (2) influence of electrically induced ventricular premature beats upon tachycardia; (3) patterns of retrograde atrial activation during tachycardia; or (4) influence of functional bundle branch block on the rate of the tachycardia. Analysis of events at the onset of rather than during the tachycardia is probably less important but may also provide suggestive clues about the mechanism of reentry. Observation of the following variables may be helpful: (1) behavior of antegrade conduction at the onset of tachycardia; (2) relation of atrial and ventricular activation at the onset of tachycardia; (3) presence of retrograde ventriculoatrial (V-A) conduction; (4) prolongation of the H-V interval at the onset of tachycardia; and (5) atrial stimulation at various sites. Precise understanding of the pathophysiology of supraventricular tachycardia is important because specific therapy (pharmacologic, pacemaker or surgical) may ultimately depend on accurate knowledge of the underlying mechanisms.

Anti-Arrhythmia Agents

Inhibition of bipolar demand pacemaker by diaphragmatic myopotentials.

This report describes inhibition of a normally functioning bipolar demand pulse generator by diaphragmatic myopotentials. Transient pacemaker suppression occurred repeatedly with deep respiration, straining, the Valsalva maneuver, coughing, sneezing and laughing. When the magnet was applied, none of these maneuvers inhibited the pacemaker. Extensive investigations ruled out an intermittent electrode problem such as a wire fracture or insulation break. Sensing of diaphragmatic myopotentials should be considered in the differential diagnosis of unexplained pacemaker pauses.

Action Potentials

Normal and abnormal function of the pacemaker magnetic reed switch.

Application of the special test magnet over a demand pacemaker actuates a magnetic reed switch which converts the pacemaker to fixed-rate pacing. The magnetic reed switch is a simple and generally very reliable component. This review discusses the normal and abnormal functions of the pacemaker magnetic reed switch. An understanding of the theoretical and practical aspects of this subject is important in the overall management of patients with implanted pacemakers.

Aged

Evaluation of the sensitivity of commercially available digoxin radioimmunoassay kits.

We have evaluated the technical minimum detection limits of 12 different commercially available kits and the practical minimum detection limits of 11 kits used for the determination of the serum digoxin level by radioimmunoassay. The poor technical ability of many of the kits to distinguish between digoxin levels of 0.1 ng/ml intervals between 0 and 0.5 ng/ml and, additionally, the detection of a digoxin level up to 0.3 ng/ml with some of the kits in glycoside-free sera impose a practical working minimum detection limit of 0.5 ng/ml for the majority of these kits. We, therefore, recommend caution with interpreting or evaluating serum digoxin levels below 0.5 ng/ml.

Digoxin

Demand pacemaker arrhythmias caused by intermittent incomplete electrode fracture. Diagnosis with testing magnet.

This report describes how the testing magnet was used to diagnose intermittent and incomplete electrode fracture in two patients with an implanted demand pacemaker. During fixed-rate pacing the interval between two consecutive pacemaker spikes intermittently doubled in length, suggesting that the pulse generator was continuing to fire on time into a transiently disrupted circuit. Attenuated pacemaker spikes occurring at the anticipated time of pacemaker discharge also provided a diagnostic clue. Ventricular electrograms from the defective electrodes registered small false signals.

Adult