Multiple accessory pathways in the Wolff-Parkinson-White syndrome as a risk factor for ventricular fibrillation.
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Adult↗
Biomedical subjects
R Yee
Publications and source records attributed to R Yee.
Sinus node-atrioventricular node isolation: long-term results with the "corridor" operation for atrial fibrillation.
The "corridor" operation is designed to restore sinus rhythm to patients with atrial fibrillation by electrically isolating the sinus node, a band of atrial tissue and the atrioventricular (AV) node from the remaining atrial tissue. Nine patients with drug-refractory atrial fibrillation underwent this operation; four patients had chronic atrial fibrillation and five had paroxysmal atrial fibrillation; the mean duration of symptoms was 12 +/- 8 years. Patient ages ranged from 25 to 68 years (mean 48 +/- 12). At preoperative electrophysiologic study, no patient had evidence of an accessory AV pathway or AV node reentry. Sinus node recovery time could not be determined in five patients because of recurrent atrial fibrillation during or before programmed stimulation. At operation the corridor of atrial tissue connecting the sinus and AV nodes was successfully isolated from the remaining left and right atrial tissue in all patients. One patient required early reoperation for recurrent atrial fibrillation before hospital discharge. At the predischarge electrophysiologic study, the corridor remained isolated in all patients except for one patient who had intermittent conduction between the corridor and excluded right atrium. One patient had nonsustained atrial fibrillation and one had atrial tachycardia evident in the corridor. Atypical AV node reentry of uncertain significance was induced in one other patient. Over a total follow-up of 191 patient months (mean 21 +/- 20), seven patients remained free of atrial fibrillation. Two patients had recurrent atrial fibrillation, which in one patient was effectively controlled by a single antiarrhythmic agent. A permanent pacemaker was implanted in four patients for sinus node dysfunction.(ABSTRACT TRUNCATED AT 250 WORDS)
Arrhythmia, Sinus↗
Characteristics of accessory pathways exhibiting decremental conduction.
The prevalence, electrophysiologic characteristics and functional significance of decremental conduction over an accessory pathway were examined in this retrospective study of 653 patients who had an accessory pathway demonstrated at electrophysiologic study. Decremental conduction was identified in 50 patients (7.6%). In 15 patients with anterograde decremental conduction, the accessory pathway was right parietal or septal in 14 patients and left parietal in 1 patient. In the 40 patients with retrograde decrement, the accessory pathway was left parietal in 19, posteroseptal in 13, right parietal in 2 and right anteroseptal in 6 patients. Anterograde conduction over the accessory pathway was absent in 11 of the 40 patients with retrograde decrement. Retrograde conduction over the accessory pathway was absent in 9 patients with anterograde decrement. There was no significant difference in the accessory pathway effective refractory period, or shortest cycle length with 1:1 conduction over the accessory pathway in anterograde and retrograde directions. The shortest RR interval in atrial fibrillation between 2 preexcited QRS complexes was longer in patients with anterograde decremental conduction than in a control group of patients with anterograde-conducting accessory pathways without decremental properties. These data demonstrate that decremental conduction over accessory pathways is uncommon. Anterograde decremental conduction usually occurs in right-sided or septal pathways that often do not conduct in the retrograde direction.
Adolescent↗
Significance of minimal preexcitation in Wolff-Parkinson-White syndrome.
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Adult↗
Closed heart cryoablation of the His bundle using an anterior septal approach.
His bundle cryosurgical ablation using a closed heart anterior septal approach was used in 6 patients. There were 3 men and 3 women, aged 24 to 73 years. Three patients had atrial fibrillation and 2 patients had atrial flutter (2 with combined episodes of atrial tachycardia). One patient had atrial tachycardia. Five patients had no structural heart disease and 1 patient had left ventricular dilatation (ejection fraction, 0.35). All patients undergoing His bundle cryosurgical ablation had permanent heart block without intraoperative complications (mean follow-up, 25 months). Closed heart anteroseptal cryoablation of the His bundle is effective and is an alternative to attempted catheter ablation.
Adult↗
Effects of lidocaine and verapamil on defibrillation in humans.
Patients with automatic defibrillators frequently require chronic antiarrhythmic drug therapy or receive acute therapy with the onset of symptoms. The effects on energy requirements for defibrillation of lidocaine hydrochloride and verapamil hydrochloride, two commonly used antiarrhythmic agents, were examined in 20 successive patients undergoing corrective arrhythmia surgery. The minimum energy requirement for ventricular defibrillation before and 5 minutes after the administration of 150 mg of lidocaine intravenously (n = 8), or 10 minutes after 10 mg of verapamil intravenously (n = 12), were determined. Each patient was assigned to receive either verapamil or lidocaine. Three mesh coil defibrillating electrodes (Medtronic 6891, 6892) were sutured to the epicardium of the right and left ventricles. Ventricular fibrillation was induced using alternating current. After a minimum of 10 seconds of fibrillation, the minimum energy for defibrillation was established using sequential pulse defibrillation. The preselected drug was then infused and the ventricular defibrillation energy was again determined after 5 or 10 minutes circulation time. Lidocaine did not alter the minimum energy for defibrillation (3.0 +/- 1.4 J vs. 3.0 +/- 1.8 J, mean +/- SD), despite plasma levels of lidocaine that averaged 13.2 +/- 1.9 mumol/l. In contrast, verapamil significantly increased (3.9 +/- 2.2 J vs. 6.5 +/- 2.9 J) the minimum energy necessary for defibrillation. The difference in defibrillation energy was significantly correlated to the fall in systolic blood pressure induced by verapamil administration (r = 0.72). These data reinforce the necessity for determining efficacy of defibrillation when medication changes are instituted. Verapamil should be used with caution in patients with automatic defibrillators and marginal defibrillation threshold.
Adult↗
Predictive accuracy of electrophysiologic localization of accessory pathways.
Operative ablation of accessory pathways depends critically on preoperative localization when technical limitations preclude complete intraoperative mapping. To assess the accuracy of localization, 345 patients undergoing operative ablation were studied; 316 (91.6%) had a single accessory pathway and 29 (8.4%) had multiple accessory pathways. The electrophysiologic study was diagnostically complete and accurate in 294 patients (93%) with a single accessory pathway and 19 (61%) with multiple accessory pathways. A left lateral accessory pathway was most accurately localized with excellent sensitivity (99%) and positive predictive value (98.5%). Diagnostic errors occurred in 33 patients because of 1) incorrect localization (n = 16), 2) failure to detect a second pathway (n = 9), and 3) diagnosis of a second pathway not verified intraoperatively (n = 8). Multiple pathways were more prevalent in the group with errors (33.3% vs. 5.8%, p = 0.0001), as were unidirectional pathways (48.5% vs. 24.3%, p = 0.003). It is concluded that preoperative localization of accessory pathways is sufficiently accurate to allow intraoperative mapping to be brief and focused.
Adult↗
Reduction in defibrillator shocks with an implantable device combining antitachycardia pacing and shock therapy.
Implantable defibrillators reduce the risk of sudden death in patients with malignant ventricular arrhythmias, but significant restriction in quality of life can occur as a result of frequent device activation. To determine if a device that provides both antitachycardia pacing and shock therapy can safely reduce the frequency of shocks after implantation, 46 consecutive patients undergoing initial implantation of a defibrillator were studied. In all patients, the implanted device provided antitachycardia pacing and shock therapy. Detected tachycardia characteristics and the results of therapy were stored in the device's memory. There were 42 men and 4 women, aged 26 to 71 years (mean 58.7 +/- 13.5). Left ventricular ejection fraction ranged from 13% to 67% (mean 32.2 +/- 13.4%) and 31 patients had experienced one or more episodes of cardiac arrest. Induced arrhythmias included sustained monomorphic ventricular tachycardia in 38 patients, nonsustained polymorphic ventricular tachycardia in 2 and ventricular fibrillation in 4. Over a total follow-up period of 255 patient-months (range 1 to 13, mean 6.1), 25 patients experienced spontaneous arrhythmic events. In 22 patients, 909 episodes of tachycardia were treated by antitachycardia pacing, which was successful on 840 occasions (92.4%). Acceleration of ventricular tachycardia by pacing therapy was estimated to have occurred 39 times. Syncope occurred once during pacing-induced acceleration of ventricular tachycardia. Forty-four episodes of tachycardia in seven patients were treated directly by shocks because of short tachycardia cycle length; 88% of all detected tachycardias were treated without the need for shocks. Four patients died from cardiorespiratory failure and one patient died suddenly without any detected tachyarrhythmia.(ABSTRACT TRUNCATED AT 250 WORDS)
Anti-Arrhythmia Agents↗
Near miss sudden death in an infant with Wolff-Parkinson-White syndrome.
A 6 month old infant with known Wolff-Parkinson-White syndrome presented with an out of hospital cardiac arrest. An electrocardiogram in the emergency department demonstrated atrial fibrillation with rapid ventricular response. The child subsequently was resuscitated and underwent successful interruption of an accessory connection after failing medical therapy. This case underlines the need to reassess the indications for invasive electrophysiologic testing in young children.
Heart Arrest↗
Hypothesis testing as an approach to the analysis of complex tachycardias--an illustrative case of a preexcitation variant.
The correct elucidation of the electrophysiological substrate and mechanism(s) responsible for a complex arrhythmia requires a systematic approach to the analysis of the electrophysiological data. One approach calls for the formulation of a set of hypotheses that could explain the data obtained during the study. The hypotheses are then tested for compatibility with phenomena observed and the one that agrees with the majority of the findings would represent the most tenable explanation. We present the case of a young girl with a wide QRS complex tachycardia and a history of ventricular preexcitation that illustrates this approach. The complexities were resolved only after intraoperative analysis and surgical ablation of a right-sided accessory pathway with decremental properties, and provides further insight into our understanding of the nodoventricular Mahaim fiber.
Anti-Arrhythmia Agents↗
Defibrillation shocks increase myocardial pacing threshold: an intracellular microelectrode study.
Defibrillation is known to cause inability to pace the heart acutely, but the mechanism is unknown. This study used microelectrode techniques to directly evaluate the effect of defibrillation shocks on the pacing threshold and membrane potentials from superfused guinea pig papillary muscles. Failure of pacing stimuli to induce action potentials (pacing failure) followed shocks of 50-200 V/cm, with pacing failure duration correlated with shock intensity. Increasing pacing strength from one to three times diastolic threshold decreased the incidence and duration of pacing failure. Decreased extracellular calcium concentration and verapamil added to the superfusate increased the duration of pacing failure. Membrane potential depolarization occurred after shock, but pacing failure did not correlate with depolarization magnitude. We conclude that defibrillation shocks directly cause shock intensity-dependent increase of myocardial pacing threshold. The pacing threshold of the myocardium can be increased after defibrillation shock independent of hypoxia or shock-induced depolarization and may involve membrane changes in calcium handling.
Action Potentials↗
Catheter ablation of idiopathic exercise-induced right bundle branch block and left axis deviation ventricular tachycardia.
Catheter ablation of ventricular tachycardia was performed in a patient without evidence of structural heart disease. ECG showed ventricular tachycardia and a right bundle branch block QRS configuration with left axis deviation induced by exercise and atrial pacing. At electrophysiology, presystolic activation was found in the low septal region of the left ventricle. Radiofrequency energy delivered to this site failed to prevent tachycardia. Three direct current shocks (total energy 400 J) delivered in this region rendered the tachycardia noninducible. There were no complications. During the follow-up period of six months the patient has remained free from arrhythmia on no medication. This report expands the use of catheter ablation to patients with idiopathic ventricular tachycardia ('verapamil responsive' ventricular tachycardia) originating in the left ventricle.
Bundle-Branch Block↗
Atrioventricular nodal reentry and dual atrioventricular node physiology in patients undergoing accessory pathway ablation.
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Accessory Nerve↗
Right ventricular pressure during ventricular arrhythmias in humans: potential implications for implantable antitachycardia devices.
Implantable defibrillators use algorithms based on ventricular electrographic data to detect the onset and termination of arrhythmias, but these algorithms do not always differentiate hemodynamically stable from unstable arrhythmias. Although, ideally, left ventricular function should be used to assess the hemodynamic state, right ventricular pulse pressure can be assessed in humans on a long-term basis with a transvenous lead. The potential utility of right ventricular pulse pressure to assess hemodynamic stability was studied in 22 patients with induced ventricular arrhythmias. Right ventricular pressure was measured with use of a transvenous right ventricular endocardial pacing lead with a piezoelectric bender pressure sensor 3 cm from its tip. Single ventricular premature paced beats administered in up to a bigeminal frequency did not alter the mean right ventricular pulse pressure (control 33.7 +/- 26, bigeminy 35.7 +/- 26 mm Hg). Twenty-one episodes of induced ventricular tachycardia were studied in the electrophysiology laboratory. Five seconds after tachycardia induction, hemodynamically stable ventricular tachycardia had a longer cycle length (294 +/- 41 ms) and the right ventricular pulse pressure ratio was higher (0.55 +/- 0.26) than that in unstable ventricular tachycardia (cycle length 256 +/- 55 ms, p = 0.06; pulse pressure ratio 0.26 +/- 0.09, p less than 0.05). Twenty episodes of ventricular fibrillation were induced in eight patients. One second after induction, right ventricular pulse pressure decreased from 25 +/- 5 to 6 +/- 3 mm Hg (p less than 0.05). On the first beat after defibrillation, right ventricular pulse pressure increased to 24 +/- 14 mm Hg, a level not significantly different from that before the induction of ventricular fibrillation.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Value of a revised procainamide test in the Wolff-Parkinson-White syndrome.
A shortest preexcited RR interval less than 250 ms during atrial fibrillation identifies the patient with Wolff-Parkinson-White syndrome potentially at risk for ventricular fibrillation. Loss of preexcitation after infusion of up to 10 mg/kg of procainamide during sinus rhythm has been reported to correlate with a slow ventricular response during atrial fibrillation and has been proposed as a noninvasive test to establish risk of sudden death in these patients. Others have failed to establish this relation and have questioned the usefulness of the procainamide test. Such conflicting results were hypothesized to be a result of differing dosages and methodology. Consequently, this study tested the effect of incremental doses of procainamide (to a cumulative dose of 1 g) on the anterograde effective refractory period of the accessory pathway and related the reliability of the procainamide test to the dose at which preexcitation was lost. The effect of procainamide on the anterograde effective refractory period of the accessory pathway was dose dependent; patients who lost preexcitation had a steeper dose-response curve. Loss of preexcitation by a cumulative dose of 550 mg provided the best balance for sensitivity (60%) and specificity (89%) in identifying patients with preexcited shortest RR greater than 250 ms. Specificity fell steeply after this dosage and higher doses were not useful. The diagnostic accuracy of the procainamide test is critically related to dosage and method of infusion.
Adolescent↗
Intravenous adenosine triphosphate during wide QRS complex tachycardia: safety, therapeutic efficacy, and diagnostic utility.
PURPOSE: Inappropriate administration of intravenous verapamil to patients with wide QRS complex tachycardia due to ventricular tachycardia or atrial fibrillation with Wolff-Parkinson-White syndrome occurs frequently because of misdiagnosis, and may precipitate a cardiac arrest. We evaluated the safety and the diagnostic and therapeutic utility of adenosine triphosphate administered to a consecutive series of 34 patients during wide QRS complex tachycardia due to a variety of mechanisms. PATIENTS AND METHODS: Patients who had a hemodynamically and electrically stable, monomorphic, wide (greater than 120 msec) QRS complex tachycardia induced during an invasive cardiac electrophysiologic test were studied. Hemodynamic stability was defined by a systolic blood pressure greater than 80 mm Hg and no clinical evidence of cerebral or myocardial ischemia. Adenosine triphosphate, 20 mg, was administered as a rapid intravenous bolus via a peripheral vein during wide QRS complex tachycardia. Five surface electrocardiogram leads, at least three intracardiac electrograms, and blood pressure were monitored. RESULTS: Ventricular tachycardia was present in 14 patients (mean age 50.6 +/- 19 years, cycle length 326 +/- 67 msec) and adenosine triphosphate terminated the arrhythmia in one case. Ventricular tachycardia cycle length did not change. Among 10 patients with supraventricular tachycardia with mechanisms not involving the AV node (average ventricular cycle length 346 +/- 82 msec), one case of ectopic atrial tachycardia was terminated. The ventricular rate was transiently increased in patients with Wolff-Parkinson-White syndrome and atrial fibrillation (average R-R interval 351 +/- 84 msec in control and 317 +/- 82 msec after adenosine triphosphate, p less than 0.001). Reentrant tachycardias involving the AV node (cycle length 302 +/- 52 msec) terminated in seven of 10 patients. The drug was well tolerated, and no patient developed hemodynamic compromise necessitating cardioversion as a result of adenosine triphosphate. CONCLUSION: In the setting of electrophysiology testing, adenosine triphosphate is a safe agent, even when administered inappropriately during arrhythmias for which it is relatively ineffective, such as ventricular tachycardia, and Wolff-Parkinson-White syndrome with atrial fibrillation. It is an effective agent in terminating supraventricular tachycardia involving the AV node. Tachycardia termination following adenosine triphosphate, when used as a diagnostic test to indicate obligatory participation of the AV node, had a sensitivity of 70%, specificity of 92%, and a positive predictive accuracy of 85%. Thus, adenosine triphosphate also has diagnostic utility, but should be used after the appropriate arrhythmia diagnosis has been made based on the clinical history and analysis of the 12-lead electrocardiogram.
Adenosine Triphosphate↗
Skeletonization of the atrioventricular node for AV node reentrant tachycardia: experience with 32 patients.
We describe our experience with operative therapy for atrioventricular (AV) node tachycardia using an anatomically guided procedure. The operative rationale was to dissect the AV node from most of its atrial inputs (AV node "skeletonization") with the intent of altering the perinodal substrate and preventing reentry. The anteroseptal and posteroseptal regions were initially approached epicardially to facilitate identification of anatomical structures. Under normothermic cardiopulmonary bypass, the right atrial septum was mobilized and the intermediate AV node was exposed anterior to the tendon of Todaro. Atrioventricular node conduction was monitored electrocardiographically throughout the procedure. Ablation of concomitant accessory pathways was done prior to AV node skeletonization. Thirty-two patients aged 9 to 67 years (mean age, 30 years) underwent operation. Five patients had concomitant accessory pathways in addition to AV node reentry. At electrophysiological study before discharge, no patient had AV block although anterograde and retrograde Wenckebach cycle lengths were significantly prolonged. Six patients had retrograde AV block. Twenty-nine patients are free from arrhythmia and require no antiarrhythmic medication after a follow-up of 1 month to 45 months (mean follow-up, 17 months). Three patients had recurrence of tachycardia ten days, 2 months, and 7 months postoperatively. All patients subsequently had a successful reoperation.
Adolescent↗
Surgical epicardial ablation of left ventricular pathway using sling exposure.
We report our experience with 43 consecutive patients with left free wall pathways operated on since December 1988 using a modified direct epicardial approach through a medial sternotomy, without the adjunct of normothermic cardiopulmonary bypass. The left atrioventricular sulcus is exposed by dislocating the heart cephalad and to the right using a sling made of a large sponge passed around the ventricle through the transverse sinus. While the arterial pressure is monitored, the heart is positioned to obtain adequate exposure without compromising the ventricular function. The left atrioventricular junction is exposed using a direct approach. The epicardium is incised along the ventricular edge and a plane of dissection is identified and opened using blunt dissection over the ventricular wall. The entire left atrioventricular junction can be exposed. After dissection, electrophysiological testing is repeated to assess accessory pathway conduction. Epicardial cryoablation was used when accessory pathway conduction was not present (42 patients). Transmural cryoablation was used under normothermic cardiopulmonary bypass when accessory pathway conduction persisted after dissection (subendocardial pathway). In all, cardiopulmonary bypass was not used in 41 patients. There was one early relapse that required transmural cryoablation. There were no complications.
Adult↗