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Biomedical subjects

E L Pritchett

Publications and source records attributed to E L Pritchett.

At least 109 records · Page 6Linked to original sources
PubMed1979

Atypical patterns of retrograde conduction over accessory atrioventricular pathways in the Wolff-Parkinson-White syndrome.

Patterns of ventriculoatrial conduction have been used to distinguish retrograde conduction over an accessory atrioventricular pathway from that over the normal atrioventricular conduction system. Ventriculoatrial conduction at a constant interval during incremental ventricular pacing and during progressive prematurity of ventricular extrastimuli has been considered characteristic of conduction over an accessory pathway. We describe three patients with the Wolff-Parkinson-White syndrome who had progressive or sudden increments in ventriculoatrial conduction over an accessory pathway during fixed-rate ventricular pacing or during introduction of ventricular extrastimuli. Such properties have been considered characteristic of conduction over the normal atrioventricular conduction system. We conclude that retrograde conduction over accessory pathways may resemble conduction over the normal atrioventricular conduction system.

Adult↗
PubMed1979

Ventriculoatrial intervals: diagnostic use in paroxysmal supraventricular tachycardia.

Reciprocating tachycardias due to reentry either within the atrioventricular (AV) node or using an accessory AV pathway are a common cause of paroxysmal supraventricular tachycardia in humans. Unfortunately, although of potential therapeutic value, differentiation of these forms of reciprocating tachycardia may be difficult and require detailed electrophysiologic study. To develop diagnostic criteria that permit exclusion of participation of an accessory AV pathway in reciprocating tachycardia without extensive laboratory testing, results of electrophysiologic studies were examined in 50 patients with Wolff-Parkinson-White syndrome, 15 patients with accessory AV pathways that conducted only in the ventriculoatrial direction, and 15 patients with reentry within the AV node. The interval between onset of ventricular activation and both earliest recorded atrial activity (V-Amin) and high lateral right atrial electrogram (V-HRA) was measured during tachycardia. A V-Amin of 61 ms or less or V-HRA of 95 ms or less did not occur in patients with accessory AV pathways, but occurred frequently (12 of 15 and seven or eight, respectively) in patients with reentry within the AV node. Therefore, in patients with paroxysmal reciprocating tachycardias, V-A interval measurements provide a screening test capable of excluding participation of an accessory AV pathway.

Adolescent↗
PubMed1978

Effect of catheter position on the initiation of atrial echoes with atrial pacing and premature stimulation in patients with accessory pathways.

Eleven patients with an accessory pathway and reciprocating tachycardia were studied using both fixed rate atrial pacing and the atrial extrastimulus technique. Six of the patients had an accessory pathway that conducted in both the anterograde and retrograde direction; but the effective refractory period of their accessory pathway in the anterograde direction was relatively long and was greater than the longest coupling intervals that initiated atrial echoes. Five patients had an accessory pathway that conducted only in the retrograde direction. The extrastimulus technique could be used with stimulation sites near to and remote from the accessory pathway in 10 of the 11 patients. Atrial echoes were initiated by a single atrial extrastimulus at both sites in 7 of the 10 patients, and in each patient the upper limit of the echo zone was longer with stimulation at the site near the accessory pathway. In the other three patients atrial echoes were initiated only during stimulation at the site near the accessory pathway because either atrial refractoriness or atrioventricular nodal refractoriness was encountered before the echo zone was entered during stimulation at the site remote from the accessory pathway. Differences in the longest cycle length that initiated an atrial echo during fixed rate atrial pacing were similarly demonstrated in three patients. In these three patients, pacing at the site near the accessory pathway initiated echoes at a longer cycle length than pacing at the site remote from the accessory pathway. In three other patients the electrophysiologic characteristics of atrioventricular conduction prevented a demonstration of these differences. Catheter position is an important variable in the initiation of atrial echoes in patients with accessory pathways.

Arrhythmias, Cardiac↗
PubMed1978

Cryoablation of drug-resistant ventricular tachycardia in a patient with a variant of scleroderma.

A 37-year-old man with a benign variant of scleroderma (CRST syndrome: calcinosis circumscripta, Raynaud's phenomenon, sclerodactyly, and telangiectasia) presented with recurrent ventricular tachycardia. Preoperative electrophysiologic study suggested that the mechanism of tachycardia was an ectopic pacemaker focus in the right ventricle. Right ventricular dilatation, tricuspid insufficiency, normal pulmonary pressures, and normal coronary arteries were also demonstrated. At surgery, epicardial mapping localized the site of origin of ventricular tachycardia to the anterior right ventricle near the crista supraventricular. Intramural recordings of the site of tachycardia demonstrated autonomous activity unreflected on the peripheral ECG during brief periods of sinus rhythm. Local epicardial cooling of this area with a cryoprobe promptly terminated ventricular tachycardia with resumption of tachycardia on warming. The focus was ablated by freezing the area at -60 degrees C. The patient remained free of dysrhythmia on no anti-arrhythmic agents for eight months at which time he had a single recurrence of ventricular tachycardia from a different site in the right ventricle. This technique offers a method for ablating sites of dysrhythmia arising in diffusely diseased myocardium.

Adult↗
PubMed1978

Determinants of antegrade echo zone in the Wolff-Parkinson-White syndrome.

Forty-five patients with the Wolff-Parkinson-White syndrome and reciprocating tachycardia which utilized the atrioventricular (A-V) node for antegrade conduction and an accessory pathway for ventriculo-atrial (retrograde) conduction were studied. The extrastimulus technique in the right atrium and coronary sinus at multiple pacing cycle lengths was used. Three types of "echo zones" were defined by the relationship of the antegrade effective refractory period (ERP) of the accessory pathway, the longest coupling interval accompanied by an atrial echo, the ERP of the A-V node, and the functional refractory period of the atrium. Eighteen of 45 patients (40%) had more than one type of echo zone demonstrated by changing either pacing site or pacing cycle length or both. Pacing site and intraventricular conduction delay were found to have important effects on the longest coupling interval accompanied by an atrial echo in those echo zones in which the longest coupling interval accompanied by an atrial echo was less than the antegrade ERP of the accessory pathway. The echo zone is a useful concept to explain the physiology of the common reciprocating tachycardia in patients with the Wolff-Parkinson-White syndrome. However, the echo zone is profoundly affected by pacing site and pacing cycle length. When these variables are changed, many patients can be shown to have more than one type of echo zone. Studies of the echo zone have limited value as therapeutic guides.

Cardiac Pacing, Artificial↗
PubMed1978

Epicardial mapping in the Wolff-Parkinson-White syndrome.

Epicardial mapping provides a method for defining antegrade and retrograde sites of pre-excitation. It is best undertaken only after a careful, detailed preoperative electrophysiological study has been performed. The potential pitfalls of the technique are many and technical expertise must be constantly available to maintain a functioning system. For these reasons, it is not likely to lend itself to widespread application. The same techniques can be applied to localization of the site of origin of atrial or ventricular dysrhythmias, localization of myocardial ischemia and infarction, as well as to differentiate between epicardial delays due to conduction delay and those caused by intramural myocardial delay.

Arrhythmias, Cardiac↗
PubMed1978

Temporary, catheter-induced block in accessory pathways.

Catheter-induced conduction delay or block in the accessory atrioventricular pathway of four patients with the preexcitation syndrome was observed. Block in the accessory pathway occurred during routine catheter placement and lasted from 90 seconds--14 hours. All of the pathways were in locations readily accessible to catheter trauma, located in the right anterior septal/paraseptal area in three patients, and in the posterior septum near the orifice of the coronary sinus in the fourth. The location of the acessory pathway was confirmed at surgery by endocardial mapping in three of the four patients. The fourth patient did not undergo survey. These findings suggest the need for caution in performing and interpreting electrode catheter studies which are undertaken to document the presence of accessory pathways.

Adult↗
PubMed1978

Reentry within the atrioventricular node in man: a reassessment.

6 patients with reentrant supraventricular tachycardia were studied using the atrial extra-stimulus (S1-S2) technique. 3 patients had smooth curves of H1-H2 intervals plotted against A1-A2 intervals, and echoes occurred only in the relative refractory period of the AV node. These patients met traditional criteria for reentry within the AV node, but all 3 were found to have accessory pathways which functioned only in the retrograde direction. 3 other patients had discontinuous curves of H1-H2 intervals plotted against A1-A2 intervals, and the echo zone was confined to coupling intervals producing the longer of the two observed AV node responses. Accessory pathways could not be demonstrated in these latter 3 patients. In patients with accessory pathways the effect of changing atrial pacing site on the echo zone was studied. Pacing at a site remote from the accessory pathway shifted the echo zone to shorter coupling intervals. Some patients previously thought to have reentry within the AV node may have had accessory pathways which conducted only in the retrograde direction. The prevalence of this syndrome is unknown but is important because ablation of the accessory pathway is curative.

Atrioventricular Node↗
PubMed1978

Surgical treatment of tachyarrhythmias in patients with both an Ebstein anomaly and a Kent bundle.

The report relates experience with six patients with Kent bundles, five of whom had the Wolff-Parkinson-White syndrome, operated upon for tachyarrhythmias caused by the presence of the pathway. It was successfully divided in four patients, its antegrade conduction capacity interrupted in one, and a failure occurred in the sixth patient. In the three patients who had a Kent bundle with a short effective refractory period for antegrade conduction, the life-endangering potential of the Kent pathway was corrected. To emphasize the complexities of the tachyarrhythmias in Ebstein's anomaly, two patients have mild but controllable postoperative supraventricular tachyarrhythmias (SVT) due to a Mahaim pathway. The surgical problems encountered in these patients are reviewed.

Adolescent↗
PubMed1978

The surgical anatomy of Kent bundles based on electrophysiological mapping and surgical exploration.

The development of the procedure for interruption of a Kent bundle for the correction of the tachyarrhythmias associated with the Wolff-Parkinson-White syndrome has been hampered by the lack of anatomic descriptions of the pathways. Only 21 descriptions are given in enough detail for guidance to the surgeon. Our experience with our first 100 patients operated upon for serious dysrhythmias associated with Kent bundles has supplemented this information. In our first 40 patients the Kent was divided in 22 of 39, one having elective and four having forced interruption of the His bundle, with success in 28. In the next 60 the Kent was divided in 52 of 59 attempts, one had elective and three had forced His bundle interruption, and the success rate was 56 of 60 patients. This increased success occurred because we learned the following: (1) The anomalous pathways are best approached through the atrium and can be for out in the fat, even subepicardial in the coronary sulcus or adjacent to the anulus. (2) Interruption should be started with an incision made just above the anulus fibrosus. (3) Posterior septal pathways can be adjacent to the His bundle or in the septum from this point posteriorly to the crux. (4) Anterior septal pathways can be divided and the His bundle protected. The details for the approach to the right and left free wall, posterior septal, and anterior septal pathways will be given. The approach to all pathways is now safe enough to allow the surgeon to offer this operation to patients with life-threatening tachyarrhythmias as well as the ones with rhythm disturbances that are either burdensome or impossible to treat medically.

Arrhythmias, Cardiac↗
PubMed1977

Atrial fibrillation in the preexcitation syndrome.

One hundred patients with proved accessory pathways of the Kent bundle type were studied with multiple intracardiac catheters. During the procedure 16 had atrial fibrillation. Two patterns of induction of atrial fibrillation were noted. In most patients an earlier than expected atrial deflection appeared in one of the atrial recordings and was followed by atrial flutter (cycle length less than 220 msec) or atrial fibrillation either immediately or after a brief period of acceleration of atrial rate. In a few patients, intraatrial conduction delay, manifested as 2:1 block or Wenckebach block from the right to the left atrium or vice versa, occurred before the onset of atrial fibrillation. The incidence of atrial fibrillation was not statistically related to any associated cardiac abnormalities. A significantly large incidence of ventricular fibrillation was recorded in patients who had documented atrial fibrillation either before admission or during the catheter study.

Adult↗
PubMed1977

Ventricular apical vents and postoperative focal contraction abnormalities in patients undergoing coronary artery bypass surgery.

Ventriculograms made 9-15 months after surgery in 48 patients with normal preoperative apical contraction were reviewed to determine the influence of apical venting on apical wall motion in patients undergoing coronary bypass surgery. After interpretation of postoperative apical wall motion, the patients were subdivided into two groups. One group consisted of 34 patients who were vented by inserting a catheter through the apex of the left ventricle and the second group included 14 patients in whom no transventricular vent was made. The two groups were similar clinically and hemodynamically before surgery, and the surgical procedures were similar with the exception of vent site. Following surgery, incidences of graft patency and antegrade flow to the apex were also similar. Nineteen (56%) patients in the apically vented group had apical dyskinesia or akinesia observed on the postoperative ventriculogram while none of the patients who were not apically vented had these findings. None of the patients with apical dyskinesia or akinesia had congestive heart failure following surgery. The postoperative ventriculograms of 12 patients with mitral stenosis who underwent valvulotomy by inserting a Tubbs dilator through the apex were also analyzed. Only one patient (8.5%) had apical dyskinesia or akinesia. Since the patients with mitral stenosis probably did not have significant coronary artery disease, it is possible that the combination of the apical vent and ischemic heart disease was responsible for the focal contraction abnormalities observed.

Cardiac Catheterization↗
PubMed1977

Cryosurgical ablation of accessory atrioventricular connections: a method for correction of the pre-excitation syndrome.

Cryothermia, a new technique for definitive treatment of the pre-excitation syndrome, is described in two patients. The first patient presented with a normal P-R interval with a delta wave and reciprocating tachycardia. Preoperative electrophysiologic study suggested a free-wall atrioventricular connection on the left posterior atrioventricular (A-V) groove. At surgery, epicardial mapping confirmed the site of pre-excitation on the posterior left ventricular (LV) wall. An electrogram arising from the accessory pathway (AP) was recorded at the site of earliest ventricular activation. Interatrial delay combined with an apparently long accessory pathway to the ventricle caused the P-R interval to appear normal. Local pressure abolished pre-excitation. The site of early ventricular activation was cooled to -60 degrees C with a specially designed cryoprobe. All evidence of pre-excitation and arrhythmias disappeared. The second patient presented with a refractory reciprocating tachycardia and was found to have an AP in the septum capable of only retrograde conduction. Retrograde conduction was abolished by applying a temperature of 0 degrees C to the anulus at this site during tachycardia. Conduction over the AP and reciprocating tachycardia returned with rewarming. Ablation of the AP was obtained by applying a temperature of -60 degrees C for 90 seconds on two occasions to the same area. The His bundle was not injured.

Adult↗