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AV Nodal Behavior After Ablation. Introduction; The objective of this report is to delineate the atrioventricular (AV) nodal electrophysiologic behavior in patients undergoing fast or slow pathway ablation for control of their AV nodal reentrant tachycardia (AVNRT).
Methods and Results: One hundred sixteen consecutive patients with symptomatic AVNRT were included. Twenty-two patients underwent fast pathway ablation with complete abolition of AVNRT in all and development of complete AV block in five patients. Of 17 patients with intact AV conduction postablation, 12 had demonstrated antegrade dual pathway physiology during baseline study, which was maintained in three and lost in nine patients postablation. Two patients with successful fast pathway ablation developed uncommon AVNRT necessitating a slow pathway ablation. Twenty-one patients demonstrated both common and uncommon forms of AV nodal reentry during baseline study. The earliest site of atrial activation was close to the His-bundle recording site (anterior interatrial septum) during common variety and the coronary sinus ostium (posterior interatrial septum) during the uncommon AV nodal reentry in all 21 patients. Ninety-six patients underwent successful slow pathway ablation. Among these, the antegrade dual pathway physiology demonstrable during baseline study (60 patients) was maintained in 25 and lost in 35 patients postablation.
Conclusion: These data suggest that: (1) dual pathway physiology may persist after successful ablation, which might be a reflection of multiple reentrant pathways in patients with AVNRT: and (2) the retrograde pathways during common and uncommon AVNRT have anatomically separate atrial breakthroughs. These findings have important electrophysiologic implications regarding the prevailing concept of the AV nodal physiology in patients with AVNRT.  相似文献   
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The Effect of Biphasic Waveform Tilt in Transvenous Atrial Defibrillation   总被引:3,自引:0,他引:3  
Atrial defibrillation can be accomplished using low energy shocks and transvenous catheters. The biphasic waveform tilt required to achieve optimal atrial defibrillation thresholds (ADFTs) is, however, not known. The effect of single capacitor biphasic waveform tilt modification on ADFT was assessed in 20 patients. Following AF induction the defibrillation pulses were delivered between the catheters positioned in the coronary sinus and the right atrium.
The single capacitor biphasic waveform shocks, delivered over the same pathways, consisted of 65% tilt (65/65 biphasic waveform) to produce an overall tilt of 88%, or 50% tilt (50/50 biphasic waveform) to produce an overall tilt of 75%. Although 65/65 biphasic waveform delivers more energy, the shorter duration 50/50 biphasic waveform reduced stored energy ADFT 21%, from 1.34 ± 0.82 J with 65/65 biphasic to 2.06 ± 0.81 J. These differences were not statistically significant. Nine patients had lower ADFT with 50/50 biphasic waveform while five patients had lower ADFT with 65/65 biphasic waveform. Equivalent reduction in ADFT was seen in the remaining six patients. The ADFT was 0.83 ± 0.65 J when both tilts were considered. In conclusion, biphasic waveform tilt modification may affect the ADFT in an individual patient. The optimal biphasic waveform for ADFT is not known.  相似文献   
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Shock Delivery Despite Abortive Shock Capability. Introduction: To describe the delivery of noncommitted implantable cardioverter defibrillator (ICD) shocks despite self-termination of ventricular arrhythmias. Abortive shock capability should eliminate the delivery of shocks for self-terminating ventricular arrhythmias. The delivery of noncommitted shocks despite abortive shock capability is, therefore, unexpected and previously unreported.
Methods and Results: Among 118 patients who received the Transvene nonthoracotomy lead system and the Jewel ICD (model 7219D), three patients (1.7%) experienced spurious, noncommitted shocks for self-terminating arrhythmias. Only one detection zone (i.e., ventricular fibrillation) had been programmed in the defibrillator in each patient. In all three patients, the ventricular arrhythmias self-terminated during the charging period. One patient received seven shocks during periods of asystole, and the other two patients received one shock each. Two different mechanisms for shock delivery in this setting were identified: one occurring in the absence of electrical activity at the end of the bradycardia escape interval (i.e., associated with bradyarrhytbmias), and the other when two sensed electrical events (i.e., escape beats) occurred during the so-called "synchronization" window of the defibrillator.
Conclusions: In rare patients with the Jewel defibrillator, shocks may be delivered for self-terminating arrhythmias despite abortive shock capability. Patients who are dependent upon pacing from their implanted defibrillator are at particular risk for shock in the aftermath of self-terminating ventricular arrhythmias. Defibrillator programming strategies aimed at eliminating or diminishing the incidence of this problem are discussed.  相似文献   
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Bundle Branch Reentrant Ventricular Tachycardia:   总被引:4,自引:0,他引:4  
Sustained Bundle Branch Reentrant Tachycardia. introduction: The clinical, electrophysiologic features and follow-up of 48 patients with inducible bundle branch reentrant (BBR) tachycardia are presented. Methods and Results: Forty-eight patients were identified in whom a diagnosis of BBR tachycardia was made during electrophysiologic evaluation. The clinical presentation was syncope or sudden death in 38 patients, and sustained palpitations during wide QRS complex tachycardia in 5 patients. Electrophysiologic studies were performed in 5 additional patients for various other reasons. Structural heart disease was present in 45 patients. Idiopathic dilated cardiomyopathy and coronary artery disease were the anatomical substrates in 19 (39%) and 24 (50%) patients, respectively, severe aortic regurgitation was present in 2 patients, and no organic heart disease was identified in 3. All 48 patients had evidence of His-Purkinje system disease. BBR tachycardia with left and right bundle branch block morphologies was induced in 46 and 5 patients, respectively, and interfascicular BBR tachycardia was initiated in 2 patients. Ventricular tachycardia of a myocardial origin was induced in 11 patients. Management of BBR tachycardia included transcatheter bundle branch ablation in 28 patients, and antiarrhythmic drug therapy in 16 patients. Four patients were treated with implantablc defibrillators. After a mean follow-up of 15.8 months in 42 patients, there were 13 deaths due to congestive heart failure, 4 sudden cardiac deaths, 3 nonsudden cardiac deaths, and 3 noncardiac related deaths. Conclusion: Sustained BBR, a form of monomorphic ventricular tachycardia, is a highly malignant arrhythmia usually seen in patients with structural heart disease. Three different types of BBR tachycardia are described. If distinguished from ventricular tachycardia of a myocardial origin, catheter ablation of the right bundle branch can be easily performed and effectively eliminates BBR. During follow-up, congestive heart failure is the most common cause of death in this population.  相似文献   
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Hepatitis B surface antigen (HBsAg) and antibody (anti-HBsAg) were determined on 442 asymptomatic heroin users and 246 controls. Of the drug-taking group, 124 used heroin intravenously and 318 nonintravenously (smoking, sniffing). Twenty-three (5.2%) heroin users were HBsAg positive and 118 (26.7%) anti-HBsAg positive, compared to three (1.2%) HBsAg positive and 28 (11.4%) anti-HBsAg positive controls, both statistically significant. HBsAg was positive in eight (6.5%) intravenous heroin users and statistically identical to 15 (4.7%) HBsAg positive nonintravenous users. Positive anti-HBsAg in 55 (44.4%) intravenous heroin users compared to 63 (19.8%) nonintravenous users, however, is statistically significicant.  相似文献   
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Optimum Electrodes for Atrial Defibrillation. Introduction : High atrial defibrillation energy requirements (ADER) in patients with chronic atrial fibrillation (AF) may limit the acceptance of transvenous atrial defibrillation. We evaluated an optimized defibrillation electrode configuration that could help to reduce the ADKR in patients with AF.
Methods and Results : We tested ten different configurations in nine dogs with AF (3.33 ± 2.92 days) induced by rapid atrial pacing. The configurations were: right atrial (RA) appendage as anode und coronary sinus (CS) as cathode; RA and innominate vein (I) as anode to CS (cathode); RA-CS (anode) to I (cathode); I-CS (anode) to RA (cathode); RA and left lateral subcutaneous patch (P) as anode to CS (cathode); RA-CS (anode) to P (cathode); P-CS (anode) to RA (cathode); superior vena cava (SVC) and CS (anode) to RA (cathode); RA-CS (anode) to SVC (cathode); and RA-SVC (anode) to CS (cathode). ADER was defined as the voltage needed to defibrillate the atria in 10% to 90% of 20 consecutive shocks. Three lead systems had ADER lower than the RA (anode) to CS (cathode) configuration, which required a mean of 143 ± 58 volts. These three were: RA-SVC (anode) to CS (cathode) 103 ± 29 V; I-CS (anode) to RA (cathode) 129 ± 39 V; and P-CS (anode) to RA (cathode) 130 ± 38 V. The remaining configurations had ADER higher than the RA (anode) to CS (cathode) configuration.
Conclusion : Adding an additional shocking electrode may reduce ADER when compared with the RA (anode) to CS (cathode) configuration. This concept could he incorporated into future implantable atrial defibrillators or used for refractory patients undergoing temporary transvenous cardioversion.  相似文献   
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Implantation of a nonthoracotomy system (Medtronic PCD or CPI Endotak) was attempted in 170 patients with ventricular tachycardia (VT) or ventricular fibrillation (VF) not requiring concomitant cardiac surgery. A nonthoracotomy system could be successfully implanted in 95 of the 115 patients with the PCD system and 49 of 55 patients receiving the Endotak lead system. In 26 patients with failed nontboracotomy system because of defibrillation threshold (DFT) > 25 joules (J), an epicardial system was implanted at the same setting. Patients receiving the two lead systems were comparable with regard to age, sex, and ejection fraction. However, since tbe PCD system offers tiered therapy multiprogrammable options, all attempts were made to implant tbis lead system in patients with VT that could be pace terminated. Mean DFT(15 ± 4.7 vs 17 ± 4.6 J;P = 0.03) and implant time (2.5 ± 0.6 vs 3.3 ± 0.7 hours; P = 0.02) were less with the Endotak lead system. There was no perioperative mortality. During a mean follow-up of 20 ± 4 months, there were eight instances of lead dislodgment in patients receiving the PCD system. Tbere were four nonsudden cardiac deaths and one sudden death in the Endotak group and three nonsudden deaths in the PCD group. Sudden cardiac death and total survival using the intention-to-treat analysis during this follow-up period were 99% and 95%, respectively. In conclusion, successful implantation, perioperative mortality, and survival rate are comparable with both lead systems; however, incorporating two defibrillating electrodes in one lead minimizes lead dislodgment and reduces implant time.  相似文献   
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