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Background: Following recent cases of nonphysiologic noise noted early after defibrillator implantation, the Canadian Heart Rhythm Society Device Committee decided to evaluate the implications of this problem., Objective: To determine the incidence and consequences of nonphysiologic noise early after defibrillator implantation., Methods: The Canadian Heart Rhythm Society Device Committee surveyed all Canadian defibrillator implanting centers regarding their implant volumes and number of cases where nonphysiologic noise had been noted early (< 24 hours) after implant over the preceding 2 years. For such cases, information regarding the manufacturer and occurrence of inappropriate shock or inhibition of pacing was reported., Results: Responses were obtained from 20 of 23 surveyed implanting centers, with a total implant volume of 4960 defibrillators per year. The occurrence of nonphysiologic noise early after implantation was noted in 25 cases over the preceding 2 years (0.25%). Noise was detected in devices of all 3 of the leading volume device manufacturers. There were 2 cases of inappropriate shocks and 2 cases of symptomatic pacing inhibition. In 4 cases, removal of the lead from the header and retesting with the analyzer confirmed normal lead function. In all cases, the noise resolved within 24 hours., Conclusion: Nonphysiologic noise early after defibrillator implantation was noted in 0.25% of procedures and was not limited to one specific manufacturer. This noise may result in an inappropriate shock or inhibition of pacing in a pacemaker-dependent patient. This transient phenomenon, possibly related to fluid and/or air in the header, appears to always resolve without surgical intervention., (Copyright © 2012 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

In canines, excessive activation of select mediastinal nerve inputs to the intrinsic cardiac nervous system induces atrial fibrillation (AF). Since ablation of neural elements is proposed as an adjunct to circumferential pulmonary vein ablation for AF, we investigated the short and long-term effects of mediastinal nerve ablation on AF inducibility. Under general anesthesia, in 11 dogs several mediastinal nerve sites were identified on the superior vena cava that, when stimulated electrically during the atrial refractory period, reproducibly initiated AF. Cryoablation of one nerve site was then performed and inducibility retested early (1-2 months post Cryo; n=7) or late (4 months post Cryo; n=4). Four additional dogs that underwent a sham procedure were retested 1 to 2 months post-surgery. Stimulation induced AF at 91% of nerve sites tested in control versus 21% nerve sites early and 54% late post-ablation (both P<0.05). Fewer stimuli were required to induce AF in controls versus the Early Cryo group; this capacity returned to normal values in the Late Cryo group. AF episodes were longer in control versus the Early or Late Cryo groups. Heart rate responses to vagal or stellate ganglion stimulation, as well as to local nicotine infusion into the right coronary artery, were similar in all groups. In conclusion, focal damage to intrinsic cardiac neuronal inputs causes short-term stunning of neuronal inducibility of AF without major loss of overall adrenergic or cholinergic efferent neuronal control. That recovery of AF inducibility occurs rapidly post-surgery indicates the plasticity of intrathoracic neuronal elements to focal injury., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Background/objective: The Canadian Heart Rhythm Society (CHRS) Device Advisory Committee was commissioned in 2006 to develop a mechanism for responding to advisories regarding cardiac rhythm device and lead performance., Methods: In the event of an advisory, the Chair classifies the advisory as urgent, semi-urgent, or routine based on the nature of the threat to the patient and the number of patients affected. The Chair uses an e-mail network with the committee members to disseminate advisory information and to assemble a consensus recommendation. Committee membership is broadly representative of the Canadian device community, including both academic and nonacademic centers, adult and pediatric specialists, and includes balanced regional representation. Recommendations are approved by the CHRS executive and made available to all implant and follow-up centers on the CHRS website., Results: With the Medtronic Fidelis lead advisory of October 15, 2007, the Chair classified the advisory as semi-urgent and initiated an e-mail discussion and preliminary survey of all Canadian implantable cardioverter-defibrillator (ICD) centers within 3 hours of advisory announcement. A CHRS membership statement was issued within 48 hours. Within 5 working days, sample letters to physicians and patients were posted for local adaptation and distribution. Complete data collection was obtained from all Canadian defibrillator centers. Analyses at 20, 25, 30, and 32 months suggest an accelerating course of failures (3.91% at 32 months, P <.0001), with a reduced likelihood of presentation with inappropriate shocks (from 56% to 21%, P = .0003)., Conclusion: A collaborative approach using an e-mail network provides a mechanism for a rapid national response to device advisories. The network allows collection of focused data on implanted device system performance and facilitates timely reporting of clinically relevant data to patients and clinicians.

We sought to determine the sites of origin of atrial tachyarrhythmias induced by activating mediastinal nerves, as well as the response of such arrhythmias to autonomic modulation. Under general anaesthesia, atrioventricular block was induced after thoracotomy in 19 canines. Brief trains of 5 electrical stimuli were delivered to right-sided mediastinal nerves during the atrial refractory period. Unipolar electrograms were recorded from 191 right and left atrial epicardial sites under several conditions, i.e. (i) with intact nervous systems and following (ii) acute decentralization of the intrathoracic nervous system or administration of (iii) atropine, (iv) timolol, (v) hexamethonium. Concomitant right atrial endocardial mapping was performed in 7 of these dogs. Mediastinal nerve stimulation consistently initiated bradycardia followed by atrial tachyarrhythmias. In the initial tachyarrhythmia beats, early epicardial breakthroughs were identified in the right atrial free wall (28/50 episodes) or Bachmann bundle region (22/50), which corresponded to endocardial sites of origin associated with the right atrial subsidiary pacemaker complex, i.e. the crista terminalis and dorsal locations including the right atrial aspect of the interatrial septum. Neuronally induced responses were eliminated by atropine, modified by timolol and unaffected by acute neuronal decentralization. After hexamethonium, responses to extra-pericardial but not intra-pericardial nerve stimulation were eliminated. It is concluded that concomitant activation of cholinergic and adrenergic efferent intrinsic cardiac neurons induced by right-sided efferent neuronal stimulation initiates atrial tachyarrhythmias that originate from foci anatomically related to the right atrial pacemaker complex and tissues underlying major atrial ganglionated plexuses.

Background and Objective: Recurrence of atrial flutter (AFl) on antiarrhythmic drugs is frequently observed. To determine the reasons for drug inefficacy, the electrophysiological parameters of AFl were studied in eight patients without drug, six patients on sotalol (Sot), eight patients on amiodarone (Amio) and four patients on propafenone (PPF) who presented to the electrophysiology laboratory for conversion of AFl by rapid atrial pacing., Methods: A quadripolar electrode catheter was positioned in the right atrium in the pathway of the AFl circuit. The duration and composition of the excitable gap (EG) were determined by premature stimuli during AFl., Results: The EG in AFl recurring on Sot (80 +/- 25 ms), Amio (78 +/- 13 ms) and PPF (83 +/- 26 ms) was not significantly different from that without drug (88 +/- 14 ms). Furthermore, a fully excitable portion of the EG was present whether with or without drug., Conclusions: AFl recurrence on Amio, PPF or Sot is associated with the continued presence of an EG and fully excitable portion. These findings explain the persistent viability of the AFl circuit despite drug therapy in these patients.

Objective: To assess the impact of adverse drug reactions on antiarrhythmic drug substitution in ambulatory patients., Setting: Tertiary care dysrhythmia clinic., Patients and Methods: A total of 671 medical records were reviewed. Sex of the study population was equally distributed, with an average age of 53 years. Follow-up averaged 26 months for patients seen more than once. Suspected adverse drug reactions and substitution of antiarrhythmic agent were used to ascertain events in patients' charts. Patients were exposed to 1253 treatment courses. The number of successive antiarrhythmic agents per patient averaged 1.8 and varied from one to seven., Results: One hundred and thirty-nine (20%) patients experienced a total of 194 adverse events (15.5% of drug courses), of which only eight (4%) were serious. Ninety-four per cent of the mostly benign adverse drug reactions were followed by a therapeutic modification: discontinuation or replacement in 87% and dosage reduction in 7%. The influence of successive drug changes was evident: the risk of a reaction was 7% in patients exposed to one agent compared with 100% in patients exposed to a seventh agent., Conclusions: First, therapeutic substitution in response to adverse drug reactions appears to be determined more by the combined expected benefit, the product of arrhythmia severity and drug efficacy, than by the severity alone of the adverse reaction; and second, the probability of an adverse drug reaction is proportional to the number of agents tried consecutively, possibly as a result of patient selection, drug selection and increased patient and doctor awareness.

Objective: To compare the diagnostic yield of transtelephonic monitoring (TTM) with Holter monitoring in patients presenting possibly arrhythmogenic symptoms., Design: A prospective comparison of Holter monitoring with TTM performed sequentially in all subjects., Setting: Tertiary arrhythmia clinic at Hôpital du Sacré-Coeur de Montréal, Montréal, Québec., Patients: One hundred consecutive patients (34 men and 66 women, mean +/- SD age 55 +/- 16 years) presenting over a two-year period for diagnosis of intermittent palpitations and/or syncope/dizziness., Interventions: Subjects first underwent 24 h Holter monitoring and then were provided with TTM for 25 +/- 13 days, with instructions to record during symptomatic episodes and subsequently to transmit the recording at their convenience., Main Results: Holter monitoring documented arrhythmia in 30 patients whereas TTM identified arrhythmia in 21. TTM was most useful in excluding arrhythmia during symptoms (34 patients) versus Holter (two patients). Neither method was useful in diagnosing syncope. Frequency of occurrence of palpitations did not predict which method would most likely yield a diagnosis but palpitations lasting longer than 2 mins were likely to be diagnosed by TTM., Conclusions: Holter and TTM are complementary studies whose combined use increases the diagnostic yield of arrhythmia. Further, TTM is of greatest use in excluding arrhythmia during intermittent symptoms.

Objective: To report a new case and review the literature of amiodarone-related epididymitis to improve knowledge of the clinical characteristics of this reaction., Design: Cohort study., Setting: Tertiary out-patient arrhythmia clinic., Patients: Males currently treated for arrhythmias with amiodarone for at least two months. Thirty-two patients were identified and all were contacted., Outcome Measures: Swelling and or/pain in the scrotum with confirmation of noninfectious epididymitis by a urologist., Data Sources: Bibliography (Medline and Embase) and databases (Manufacturer, Health Protection Branch, World Health Organisation)., Study Selection: Four articles with case reports. Databases searched for these key words: amiodarone and epididymitis., Results: A new case is reported. Twelve cases have been presented individually and six more described collectively. Times to onset range from four to 71 months, daily doses range from 200 to 800 mg. The reaction is self-limited, with or without amiodarone reduction, and does not require antimicrobial drugs, but a noninvasive urological examination may be warranted., Conclusion: Awareness by cardiologists will prevent unnecessary invasive urological investigations or antibiotic therapy.

A case of vasovagal syncope in an otherwise healthy 74-year-old woman is described. Attempts to prevent symptoms with ventricular and atrioventricular sequential temporary pacing (documented by continuous monitoring of heart rate and intra-arterial recording of blood pressure during spontaneous episodes) proved inadequate. However, the addition of a beta-blocker to permanent DDD pacing was clinically successful in markedly diminishing symptoms. The mechanisms of action of this treatment modality is discussed.

The use of an antitachycardia pacemaker for the treatment of recurrent, drug resistant nonsyncopal sustained ventricular tachycardia in a 28-year-old patient is described. The report emphasizes the role of electrocardiographic recording during manual activation of the tachycardia response in an outpatient setting. The follow-up covers 12 months with 26 spontaneous tachycardia episodes forcing the patient to go to an emergency room to monitor tachycardia termination. Mean ventricular tachycardia cycle length was 340 +/- 21 ms. Tachycardias were terminated either by the primary or secondary modality without acceleration or degeneration to ventricular fibrillation. Thus, it was possible to assess the efficacy and the safety of the termination programs. Unlike during intensive in-hospital testing, restoration of stable sinus rhythm was complicated by re-emergence of ventricular tachycardia. It is concluded that manual activation with medical supervision provides safe management of selected patients with ventricular tachycardia. However, in-hospital testing overestimated, in this case, the efficacy of tachycardia response modalities to terminate spontaneous tachycardia episodes. The customization of an antitachycardia pacemaker with an automatic implantable cardioverter/defibrillator may increase the quality of life as it would allow switching to automatic pace termination.