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Biomedical subjects

J J Gallagher

Publications and source records attributed to J J Gallagher.

At least 109 records · Page 6Linked to original sources
PubMed1983

Role of specialized conducting fibers in the genesis of "AV nodal" re-entry tachycardia.

Recent reports have suggested that an accessory bypass tract connecting the His bundle to the atrium (His-atrial fiber) may form the retrograde limb of "AV nodal" re-entry tachycardia (AVNRT). We studied 12 patients with AVNRT in whom the presence of an accessory atrioventricular fiber (Kent fiber) was excluded. We investigated the possibility of a His-atrial (H-A) fiber by examining the nature of retrograde conduction and by assessing the necessity of the atrium as a part of the re-entry pathway. Retrograde conduction through the AV node had characteristics similar to retrograde conduction over a Kent bundle; that is, retrograde conduction times were short and did not vary. With echo beats (Ae) evoked during antegrade refractory period determination early premature beats resulted in prolongation of the AH interval with no change in HAe interval. During AVNRT the A'H':H'A' ratios ranged from 2.0-8.0 (mean 4.0 +/- 1.8) and with changes in tachycardia cycle length the H'A' interval remained constant. During retrograde refractory period determination, delay occurred below the AV node without change in the H-A interval. Estimations of retrograde conduction times by all 3 methods were not significantly different (p greater than 0.2). The pattern of retrograde conduction suggests anatomical or functional specialized fibers as the retrograde limb of the tachycardia. The necessity of the atria as a part of the re-entry circuit was assessed by the introduction of atrial premature beats (APBs) in the region of the atrial septum during AVNRT in 10 patients. APBs pre-excited the atria by 40-140 ms without changing the cycle length of the tachycardia, providing strong evidence against the participation of an extranodal His-atrial fiber in AVNRT. In conclusion, retrograde conduction during AVNRT appears to take place over a functional or anatomical specialized fiber within the AV node and not over an extranodal H-A fiber.

Adolescent↗
PubMed1983

Late fractionated potentials and continuous electrical activity caused by electrode motion.

Late fractionated potentials, recorded during cardiac mapping to find the source of a ventricular arrhythmia, have been ascribed particular localizing value. Re-entry is assumed when these highly amplified and filtered recordings span diastole during tachycardia. The purpose of this study was to see if such potentials can occur artifactually. A saline soaked 7 X 2 X 3 cm sponge was sewn to the epicardium of the right ventricle in five non-infarcted, open-chest dogs. Two bipolar button electrodes, one with 1 mm and one with 1 cm interelectrode spacing, were attached to the outer surface of the sponge and a bipolar wire hook electrode was placed just under the outer surface of the sponge. Thus all three electrodes were 3 cm from the nearest myocardium yet still subjected to cardiac motion. The electrodes were recorded at gains of 4,000-40,000 and filtered to pass 50-300 hertz. One to three rapid deflections were recorded during the QRS from all electrodes. In seven of the the 15 electrode recordings, two or three additional deflections, 1100-200 microV in amplitude, occurred after the QRS. These late potentials were fractionated and recurred reproducibly from cycle to cycle. In two cases, these late fractionated potentials could be made to span diastole by rapid pacing to simulate tachycardia. Clamping the sponge to sliminate motion between the sponge and electrode caused this late activity to disappear. Thus, in highly amplified and filtered recordings, electrode motion can cause artifacts resembling late fractionated potentials and continuous electrode activity.

Animals↗
PubMed1983

Bystander accessory pathway during AV node re-entrant tachycardia.

Between 1970 and July 1980, wide QRS tachycardia due to re-entry confined to the AV node with bystander involvement of an accessory atrioventricular pathway (AAV) was documented in three of 290 patients with the Wolff-Parkinson-White syndrome studied at Duke Medical Center. In each of the patients, at least one transition between wide and narrow QRS morphology was recorded without change in either the cycle length of tachycardia or the atrial activation sequence. Two of the three patients had a single left-sided AAV (lateral, postero-lateral) showing antegrade conduction only. The third patient had two right-sided AAVs (free wall, septal), each capable of bidirectional conduction. Initiation and termination of repetitive concealed conduction into the ventricular insert of an AAV appeared to be one mechanism determining bystander AAV participation. Documentation of the retrograde sequence of atrial activation during tachycardia, and examination of the effects of interpolated premature depolarizations from both the ventricle and mid-line atrium are the most helpful features in resolving the differential diagnosis of wide QRS tachycardia in patients with W-P-W syndrome.

Adolescent↗
PubMed1983

The induction of atrial flutter and fibrillation and the termination of atrial flutter by esophageal pacing.

In patients with Wolff-Parkinson-White syndrome (WPW), it is important to assess the ventricular response during atrial flutter or fibrillation since conduction across the accessory pathway during these atrial rhythms may cause hemodynamic impairment or life-threatening ventricular arrhythmias. We have recently reported the effective use of an esophageal electrode in pacing the atrium. In this study we prospectively assessed the ability to induce atrial flutter and fibrillation by esophageal pacing in 23 patients with WPW or other electrophysiological abnormalities. An esophageal bipolar electrode with 29 mm interelectrode distance was positioned in the esophagus to record the most rapid and largest esophageal electrogram (mean distance of 36.6 +/- 2.9 cm (SD) from the nares). Pacing was performed at cycle lengths of 40-340 ms (mean 166 +/- 72), pulse durations of 7.0-9.9 ms, and currents of 10-25 mA. Atrial flutter alone was induced in 6 patients, fibrillation alone in 11 patients, and both arrhythmias in 5 patients. In one patient neither flutter nor fibrillation was induced by esophageal pacing, and fibrillation was induced only with difficulty using intracavitary pacing. Of the 11 patients with flutter, the arrhythmia was terminated in 8 by esophageal pacing at cycle lengths of 160-220 ms (mean 176 +/- 18 ms). All patients tolerated the procedure well with only mild to moderate discomfort. Therefore, esophageal pacing appears to offer an effective, well tolerated method of initiating atrial fibrillation and flutter and terminating atrial flutter and offers a potentially useful noninvasive method of following patients serially.

Adolescent↗
PubMed1983

Antegrade slow bypass conduction after closed-chest ablation of the His bundle in permanent junctional reciprocating tachycardia.

A case of permanent junctional reciprocating tachycardia in a 36-year-old woman successfully treated with closed-chest interruption of the His bundle is reported. Tachycardia had lasted for 14 years and showed a retrograde P wave (P') and RP' longer than PR' interval. The tachycardia used an anomalous pathway with a long conduction time in the retrograde direction. The atrial end of the anomalous pathway was located near the coronary sinus orifice. His ablation was accomplished by delivering a direct-current shock from a cardioversion unit to the nodal-His zone by means of a conventional electrode catheter percutaneously introduced via the femoral vein. Two shocks were necessary to obtain the desired results. After the procedure, complete atrioventricular block below the His bundle was induced, while antegrade conduction was assured through the anomalous pathway that showed decremental properties. During 7 months of follow-up, stable sinus rhythm with a long PR interval has been observed; the patient has remained free from tachycardia. Furthermore, she is not pacemaker-dependent and requires no cardioactive medication. This case demonstrates the therapeutic value of closed-chest ablation of the His bundle in a patient with permanent junctional reciprocating tachycardia, as well as demonstrating for the first time that the underlying accessory pathway is capable, in some instances, of antegrade conduction.

Adult↗
PubMed1983

Effects of energy delivery via a His bundle catheter during closed chest ablation of the atrioventricular conduction system.

In this paper we summarize our experience and report the characteristics of energy delivery in 23 patients who have undergone closed chest ablation of the normal atrioventricular (AV) conduction system for the treatment of refractory supraventricular arrhythmias. The induction of AV block was achieved by the synchronous delivery of electrical energy with a damped sinusoidal waveform utilizing a standard direct current defibrillator and a standard tripolar His bundle catheter. The procedure was well tolerated, though one patient experienced ventricular fibrillation, which was uneventfully converted with external paddles. Complete AV block was achieved in 20 of 23 patients and all were rendered arrhythmia free, though two still required antiarrhythmic drugs. A stable escape rhythm was seen in all patients with a cycle length of 1,294 +/- 243 ms. Creatine phosphokinase-MB was positive at low levels in 19 of 23 patients and cleared within 24 h. 99mTc pyrophosphate scans were faintly positive in only 2 of 22 patients. Left ventricular wall motion and ejection fractions were unchanged in 19 of 19 patients, two-dimensional echocardiography with microcavitation technique was unchanged in 12 of 12 patients, and a slight increase in pulmonary artery wedge pressure was seen in only 1 of 11 patients. Current, voltage, and their product (power) waveforms were recorded in 12 patients (12 recordings at a defibrillator setting of 200 J and 5 recordings at a defibrillator setting of 300 J) and revealed a complex voltage-current relationship due to changes occurring at the catheter electrode-tissue interface. At 200 J the peak values were 42.2 +/- 3.3 A, 2.16 +/- 0.11 kV, and 87.9 +/- 4.7 kW, while at 300 J the peak values were 58.2 +/- 2.8 A, 2.40 +/- 0.10 kV, and 134.4 +/- 6.7 kW, respectively. No instance of catheter disruption was seen, though "pitting" of the distal electrode (through which current passed) occurred in all but one catheter.

Adult↗
PubMed1983

Cutaneous pigmentation secondary to amiodarone therapy.

Amiodarone (Cordarone) is an iodinated cardiac antiarrhythmic drug that causes a slate-gray discoloration of the sun-exposed skin and a yellow-brown stippling of the cornea. Histopathologically, biopsy specimens of aminodarone pigmentation sites disclose yellow-brown refractile granules in the reticular dermis. These granules were characterized by transmission electron microscopy as being concentrically arranged intralysosomal inclusions ("myelinlike" bodies) in dermal endothelial cells and perivascular smooth-muscle cells. Electron probe x-ray analysis of these same inclusions disclosed definite peaks for iodine, evidence for the presence of amiodarone or a metabolite of the drug at these sites. Amiodarone, then, concentrates in lysosomes and causes an accumulation of lipids similar to what has been seen with other cationic amphiphilic compounds, such as the glycosphingolipid stored in Fabry's disease. Amiodarone must be recognized as a cause of a drug-induced lipid storage disease with cutaneous and corneal manifestations.

Adult↗
PubMed1982

The electrophysiologic basis and management of symptomatic recurrent tachycardia in patients with Ebstein's anomaly of the tricuspid valve.

Twenty-two patients with Ebstein's anomaly were evaluated because of recurrent tachycardia. A total of 30 accessory pathways were present in 21 of the 22 patients. Twenty-six accessory pathways were of the atrioventricular (A-V) type while four were Mahaim fibers. Multiple accessory pathways were present in eight patients. Twenty-five of the 26 accessory A-V pathways were right-sided, either in the posterior septum (12 pathways) or the posterolateral free wall (13 pathways); one patient with corrected transposition of the great arteries had a left-sided accessory A-V pathway in a lateral free wall location. Patients with accessory A-V pathways had a long minimal ventriculoatrial (V-A) conduction time during reciprocating tachycardia (192 +/- 47 ms) and usually showed a persistent complete or incomplete right bundle branch block morphology. At surgery, preexcitation was invariably localized to the atrialized ventricle. The long V-A conduction time during reciprocating tachycardia appeared to consist of late activation of the local ventricle in the region of the accessory pathway with a further delay occurring before excitation of adjacent atrium presumably due to conduction over the accessory pathway. Accessory A-V pathways were successfully sectioned with no deaths in 13 of 15 patients. On the basis of these data, certain electrocardiographic findings encountered in the study of patients with recurrent tachycardia should point to the possibility of associated Ebstein's anomaly: morphology of the surface electrocardiogram suggesting preexcitation of the right posterior septum or right posterolateral free wall as well as the combination during reciprocating tachycardia of a long V-A interval and right bundle branch block.

Adolescent↗
PubMed1982

Catheter technique for closed-chest ablation of the atrioventricular conduction system.

This report describes a catheter technique for ablating the His bundle and its application in nine patients with recurrent supraventricular tachycardia that was unresponsive to medical management. A tripolar electrode catheter was positioned in the region of the His bundle, and the electrode recording a large unipolar His-bundle potential was identified. In the first patient, two shocks of 25 and 50 J, respectively, were delivered by a standard cardioversion unit to the catheter electrode, resulting in an intra-His-bundle conduction defect. Subsequent delivery of 300 J resulted in complete heart block. In the next eight patients, an initial shock of 200 J was used. The His bundle was ablated by this single shock in six of these patients and by an additional shock of 300 J in one. In the remaining patient, conduction in the atrioventricular node was modified, resulting in alternating first and second-degree atrioventricular block. A stable escape rhythm was preserved in all patients. The procedure was well tolerated, without complications, and all patients have remained free of arrhythmia, without medication, for follow-up periods of two to six months.

Adult↗
PubMed1982

Mechanisms of regular, wide QRS tachycardia in infants and children.

A regular wide QRS tachycardia was electrocardiographically documented in 32 patients aged 1 month to 18 years. The mechanisms of the tachycardia were evaluated using standard multicatheter electrophysiologic techniques. These mechanisms included (1) orthodromic reciprocating tachycardia with bundle branch aberration (seven patients), (2) antidromic reciprocating tachycardia using single (three patients), or multiple (three patients) atrioventricular connections (Kent bundles), (3) atrial flutter with ventricular preexcitation over accessory connections (eight patients), (4) reciprocating tachycardia using a nodoventricular connection (Mahaim fiber) (five patients), and (5) ventricular tachycardia (six patients). Regular side QRS tachycardias are not rare in pediatric patients. Their mechanisms can be quite complex, and electrocardiographic analysis with respect to QRS configuration, heart rate, or the presence or absence of ventriculoatrial dissociation is not sufficient for diagnostic purposes. Our results show that considerable understanding of the mechanism of regular, wide QRS tachycardias can be obtained by multicatheter electrophysiologic study. Understanding the mechanism is essential in order to make rational use of available therapeutic options.

Adolescent↗
PubMed1982

Techniques of intraoperative electrophysiologic mapping.

Cardiac mapping during sinus rhythm and during spontaneous or induced ventricular arrhythmias is a promising technique that offers a variety of potential strategies to improve our ability to locate abnormal areas in the heart that are the seat of arrhythmias. If surgical procedures are to become more limited in scope in an attempt to salvage myocardium, mapping will need to be used to a greater extent. However, it remains to be established which mapping technique will prove most sensitive and specific in detecting sites of arrhythmia, and whether the localizing method used allows a more directed surgical intervention to be successful.

Arrhythmias, Cardiac↗
PubMed1982

Electrophysiologic effects of disopyramide phosphate in patients with Wolff-Parkinson-White syndrome.

We evaluated the electrophysiologic effects of disopyramide phosphate in 12 patients with the Wolff-Parkinson-White syndrome. Electrophysiologic studies were performed during a control period and after administering i.v. disopyramide (four bolus doses of 9.5 mg/kg over 40 minutes superimposed on a continuous infusion at 1.0 mg/kg/hour). All patients were then restudied after 3 days on oral medication in doses of 800-1200 mg/day. In all patients we tried to induce reciprocating tachycardia and atrial fibrillation. The cycle length during reciprocating tachycardia was not changed by i.v. disopyramide, but increased after oral disopyramide, from 331 +/- 53 (+/- SD) to 370 +/- 68 msec (p less than 0.01). This increase occurred predominantly as a result of prolongation of retrograde conduction time in the accessory pathway. Despite prolonging cycle length during reciprocating tachycardia, disopyramide did not prevent its induction. The shortest and mean RR intervals during atrial fibrillation were used to assess antegrade refractoriness of the accessory pathway. Intravenous disopyramide prolonged the shortest RR from 169 +/- 18 to 226 +/- 24 msec (p less than 0.0001) and the mean RR from 255 +/- 58 to 329 +/- 62 msec (p less than 0.005). Oral disopyramide prolonged the shortest RR interval from 169 +/- 18 to 248 +/- 36 msec (p less than 0.0001) and the mean RR from 255 +/- 58 to 360 +/- 93 msec (p less than 0.001). After oral disopyramide, the episodes of atrial fibrillation were shorter and self-terminating. No acute hemodynamic side effects were observed, but five patients developed gastrointestinal or anticholinergic side effects on oral disopyramide. Seven patients elected to have surgical interruption of their accessory pathways and five have been successfully treated with oral disopyramide for 14-33 months. Disopyramide appears to have beneficial electrophysiologic effects in patients with Wolff-Parkinson-White syndrome. Prolongation of refractoriness in the accessory pathway markedly slows the ventricular response during atrial fibrillation and therefore prevents the development of life-threatening arrhythmias.

Administration, Oral↗
PubMed1982

Anatomic effects of cryoablation of the atrioventricular conduction system.

Because of the value of cryoablation of the atrioventricular (AV) conduction system in treatment of refractory cardiac rhythm disorders, the anatomic effects of cryoablation on the cardiac conduction system must be defined. In this report we summarize studies done on four patients who had intractable recurrent supraventricular tachyarrhythmias or or refractory atrial flutter-fibrillation. They were treated by cryoablation of the AV conduction system and died 8-360 days postoperatively. Serial sections of the AV conduction system were studied. Cryoablation produced lesions that completely destroyed most of the AV node in three cases, the penetrating portion of the His bundle in all four cases, and the branching portion of the His bundle in two cases. The right bundle branch was not involved markedly in any case. The lesions were discrete and sharply delimited; the patient who died 8 days postoperatively had hemorrhage, necrosis and slight inflammatory infiltrate; patients who survived for 49-360 days showed collagen deposition. The AV nodal artery and its branches showed slight to marked intimal thickening in three cases. Small, partly organized thrombi were present just behind the tricuspid valve in two patients. We conclude that cryoablation of the AV conduction system produced discrete cardiac lesions that did not markedly damage the tricuspid valve or aorta.

Adolescent↗