Catheter-induced mechanical trauma to accessory pathways during radiofrequency ablation: incidence, predictors and clinical implications

AbstractOBJECTIVESTo evaluate the incidence, predictors and clinical implications of nonintentionally catheter-induced mechanical trauma to accessory pathways during radiofrequency ablation procedures.BACKGROUNDData on the incidence and significance of catheter-induced trauma to accessory pathways are scarce.METHODSConsecutive patients (n = 381) undergoing radiofrequency ablation of accessory pathways at two different institutions were closely monitored for appearance of mechanical block of accessory pathways during catheter manipulation.RESULTSMechanical trauma to accessory pathways was observed in 37 (9.7%) patients. According to a multivariate analysis, the only independent variable associated with this phenomenon was the anatomical pathway location (p = 0.0001). The incidence of trauma of either right anteroseptal (38.5%) or right atriofascicular pathways (33.3%) was significantly greater than that of pathways (≤10%) at all remaining locations (p < 0.0001). The duration of conduction block observed ranged from ≤1 min to >30 min in 19% and 35% of patients, respectively. “Immediate” application of radiofrequency pulses at sites of mechanical block (<1 min after occurrence) was associated with a 78% long-term success rate at follow-up. This contrasted with a 25% long-term success rate in patients in whom pulses were delivered 30 min after occurrence of block (“delayed pulses”). Finally, in 24% of patients persistent trauma-induced conduction block led to discontinuation of the ablation procedure.CONCLUSIONSTrauma to accessory pathways is more common than previously recognized and frequently results in prolongation or discontinuation of the ablation procedure and in lower success rates. The only independent predictor of catheter-trauma to accessory pathways is the pathway location

Temporal Variability in Electrocardiographic Indices in Subjects With Brugada Patterns

Introduction: Patients with Brugada electrocardiographic (ECG) patterns have differing levels of arrhythmic risk. We hypothesized that temporal variations in certain ECG markers may provide additional value for risk stratification. The present study evaluated the relationship between temporal variability of ECG markers and arrhythmic outcomes in patients with a Brugada pattern ECG. Comparisons were made between low-risk asymptomatic subjects versus high-risk symptomatic patients with a history of syncope, ventricular tachycardia (VT) or ventricular fibrillation (VF). Methods: A total of 81 patients presenting with Brugada patterns were recruited. Serial ECGs and electronic health records from January 2004 to April 2019 were analyzed. Temporal variability of QRS interval, J point-Tpeak interval (JTp), Tpeak-Tend interval (Tp-e), and ST elevation (STe) in precordial leads V1-3, in addition to RR-interval from lead II, was assessed using standard deviation and difference between maximum and minimum values over the serial ECGs. Results: Patients presenting with type 1 Brugada ECG pattern initially had significantly higher variability in JTp from lead V2 (SD: 33.5 ± 13.8 vs. 25.2 ± 11.5 ms, P = 0.009; max-min: 98.6 ± 46.2 vs. 78.3 ± 47.6 ms, P = 0.047) and ST elevation in lead V1 (0.117 ± 0.122 vs. 0.053 ± 0.030 mV; P = 0.004). Significantly higher variability in Tp-e interval measured from lead V3 was observed in the VT/VF group compared to the syncope and asymptomatic groups (SD: 20.5 ± 8.5 vs. 16.6 ± 7.3 and 14.7 ± 9.8 ms; P = 0.044; max-min: 70.2 ± 28.9 vs. 56.3 ± 29.0 and 43.5 ± 28.5 ms; P = 0.011). Conclusion: Temporal variability in ECG indices may provide additional value for risk stratification in patients with Brugada pattern

Mode of onset of torsade de pointes in congenital long QT syndrome

Objectives.We sought to describe the mode of onset of spontaneous torsade de pointes in the congenital long QT syndrome.Background.Contemporary classifications of the long QT syndrome (LQTS) refer to the congenital LQTS as “adrenergic dependent” and to the acquired LQTS as “pause dependent.” Overlap between these two categories has been recognized, and a subgroup of patients with “idiopathic pause-dependent torsade” has been described. However, it is not known how commonly torsade is preceded by pauses in the congenital LQTS.Methods.We reviewed the electrocardiograms (ECGs) of all our patients with congenital LQTS evaluated for syncope or sudden death (30 patients). Documentation of the onset of torsade de pointes was available for 15 patients. All these patients had “definitive LQTS” by accepted clinical and ECG criteria.Results.Pause-dependent torsade de pointes was clearly documented in 14 of the 15 patients (95% confidence interval 68% to 100%). The cycle length of the pause leading to torsade was 1.3 ± 0.2 times longer than the basic cycle length, and most pauses leading to torsade were unequivocally longer than the preceding basic cycle length (80% of pauses were >80 ms longer than the preceding cycle length).Conclusions.The “long-short” sequence, which has been recognized as a hallmark of torsade de pointes in the acquired LQTS, plays a major role in the genesis of torsade in the congenital LQTS as well. Our findings have important therapeutic implications regarding the use of pacemakers for prevention of torsade in the congenital LQTS

Complete Atrioventricular Block-Induced Torsade de Pointes, Manifested by Epilepsy

Complete atrioventricular (AV) block is frequently regarded as a cause of informed syncopal attacks, even though the escape rhythm is maintained. Torsade de pointes (TdP) may be a significant complication of AV block associated with QT prolongation. Here, we report the case of a 42-year-old female who was referred to our hospital due to recurrent seizure-like attacks while taking anti-convulsant drugs at a psychiatric hospital. TdP with a long QT interval (corrected QT = 0.591 seconds) was observed on an electrocardiogram (ECG) taken in the emergency department. The patient's drug history revealed olanzapine as the suspicious agent. Even after the medication was stopped, however, the QT interval remained within an abnormal range and multiple episodes of TdP and related seizure-like symptoms were found via ECG monitoring. A permanent pacemaker was thus implanted, and the ventricular rate was set at over 80 beats/min. There was no recurrence of tachyarrhythmia or other symptoms

Ventricular fibrillation treated by cryotherapy to the right ventricular outflow tract: a case report.

BACKGROUND: Arrhythmias originating from the right ventricular outflow tract are generally considered benign but cases of cardiac arrest have been described, usually associated with polymorphic ventricular tachycardia or extrasystoles with short coupling intervals. CASE PRESENTATION: We report the case of a 54-year-old Caucasian woman with symptomatic right ventricular outflow tract arrhythmias without structural heart disease who suffered a ventricular fibrillation arrest without prior malignant clinical features. Cryoablation was performed and an implantable cardioverter defibrillator was implanted. She has since been free of arrhythmia for 7 years and has asked that the implantable cardioverter defibrillator not be replaced when the battery becomes depleted. CONCLUSIONS: Although usually benign, right ventricular outflow tract tachycardia can be life-threatening. Even the most malignant cases can be cured by ablation

Epinephrine-Induced Polymorphic Ventricular Tachycardia in a Patient With Congenital Long QT Syndrome

A 24-year-old woman presented to the department of plastic surgery for surgical excision of a nevus on her nose. Although her history failed to reveal any cardiac disease, her pre-operative electrocardiogram (ECG) showed an extremely prolonged QT interval of up to 528 msec. Repeated history-taking after admission revealed three syncopal episodes associated with both physical and emotional stress, and because the two-dimensional echocardiography and exercise ECG test were normal except for the prolonged QT interval, an epinephrine test was done to assess QT interval changes after an epinephrine infusion. Immediately after a bolus injection of epinephrine (0.1 µg/kg), marked prolongation of the QT interval developed, followed by polymorphic ventricular tachycardia which was immediately terminated with direct current shock, resulting in the diagnosis of a long QT syndrome (LQTS), probably type 1. Gene studies were recommended, but declined by the patient and her family. She was instructed to avoid competitive sports, and a β-blocker was prescribed after which she remained symptom-free