A case report of an unusual cause of increased impedance after generator exchange.

Background: Remote monitoring has emerged as a complement to in-person care for patient with cardiac implantable electronic devices (CIEDs). It provides the care team with information about device integrity, programming issues, or other medical data (i.e. arrhythmias) and since 2015 has been recognized as a part of standard management by the Heart and Rhythm Society for all patients with CIEDs. However, while it can provide invaluable information to providers, the volume of generated data can increase the risk of oversight. We present a novel case of apparent device malfunction that on closer scrutiny was obvious, but provides a lesson in the mechanisms by which data can be artifactual. Case summary: A 62-year-old male presented after his cardiac resynchronization therapy-defibrillator (CRT-D) alerted him that his device was at an elective replacement interval (ERI). He underwent an uncomplicated generator exchange; however, 2 weeks later, a remote alert showed that his device was at ERI and all impedances were above the upper limit. Device interrogation the following day demonstrated that the new device was functioning appropriately and his home monitor had in fact paired with his old generator. He obtained a new home monitor, and subsequent remote transmissions have demonstrated that his device is functioning appropriately. Discussion: This case demonstrates the importance of careful review of details from home-monitoring data. While concerning for device malfunction, there could be alternative causes when alerts are generated by remote monitoring. To our knowledge, this is the first report of this mechanism of alert via a home-monitoring device and should be considered when reviewing unusual remote download data.

Dofetilide-Associated QT Prolongation: Total Body Weight Versus Adjusted or Ideal Body Weight for Dosing.

Dofetilide is an antiarrhythmic drug with dosing based on the Cockcroft-Gault formula using total body weight (TBW). We investigated the impact of calculating dofetilide dose using adjusted body weight (ABW) or ideal body weight (IBW) on subsequent dose reduction or discontinuation. We conducted a retrospective review of 265 patients admitted to an academic medical center for initiation of dofetilide using TBW. Dosing was recalculated using ABW or IBW. Patients who would have received a reduced dose using ABW or IBW (reduced dose group) were compared with patients whose dose would not have changed (same dose group). Manual measurement of QT intervals was performed. We found that Forty-one of 265 patients (15%) would have received a lower initial dose of dofetilide based on ABW. Patients in this reduced dose group had 2.95 times greater odds of drug discontinuations or dose reductions due to QTc prolongation (95% confidence interval, 1.47-5.90; P < 0.01) compared with the same dose group. Seventy-seven of 265 patients (29%) would have received a lower initial dose of dofetilide based on IBW. Patients in this reduced dose group had 1.78 times greater odds of drug discontinuations or dose reductions due to QTc prolongation (95% confidence interval, 0.98-3.21; P = 0.056) compared with the same dose group. These data suggest that caution should be used when dosing dofetilide using TBW, as it may lead to a greater frequency of dose reduction or discontinuation compared with dosing using ABW or IBW.

Clinical and echocardiographic response of apical vs nonapical right ventricular lead position in CRT: A meta-analysis.

Background: Traditionally the right ventricular (RV) pacing lead is placed in the RV apex in cardiac resynchronization therapy (CRT). It is not clear whether nonapical placement of the RV lead is associated with a better response to CRT. We aimed to perform a meta-analysis of all randomized controlled trials (RCTs) that compared apical and nonapical RV lead placement in CRT. Methods: We searched PubMed, EMBASE, Cochrane, Scopus, and relevant references for studies and performed meta-analysis using random effects model. Our main outcome measures were all-cause mortality, composite of death and heart failure hospitalization, improvement in ejection fraction (EF), left ventricle end-diastolic volume (LVEDV), left ventricle end-systolic volume (LVESV), and adverse events. Results: Seven RCTs with a total population of 1641 patients (1199 apical and 492 nonapical) were included in our meta-analysis. There was no difference in all-cause mortality (5% vs 4.3%, odds ratio (OR) = 0.86; 95% confidence interval (CI) 0.45-1.64; P = .65; I2 = 11%) and a composite of death and heart failure hospitalization (14.2% vs 12.9%, OR = 0.92; 95% CI: 0.61-1.38; P = .68; I2 = 0) between apical and nonapical groups. No difference in improvement in EF (Weighted mean difference (WMD) = 0.37; 95% CI: -2.75-3.48; P = .82; I2 = 68%), change in LVEDV (WMD = 3.67; 95% CI: -4.86-12.20; P = .40; I2 = 89%) and LVESV (WMD = -1.20; 95% CI: -4.32-1.91; P = .45; I2 = 0) were noted between apical and nonapical groups. Proportion of patients achieving >15% improvement in EF was similar in both groups (OR = 0.85; 95% CI: 0.62-1.16; P = .31; I2 = 0). Conclusion: In patients with CRT, nonapical RV pacing is not associated with improved clinical and echocardiographic outcomes compared with RV apical pacing.

Pseudo cryomapping for ablation of atrioventricular nodal reentry tachycardia: A single center North American experience.

BACKGROUND: Most literature for cryoablation of atrioventricular nodal reentry tachycardia (AVNRT) is based on -30 degree celsius cryomapping with 4 & 6 mm distal electrode catheters. The cryomapping mode is not available on the 6 mm cryocatheter in the United States. We describe a technique for 'pseudo' mapping at -80° using a 6 mm cryocatheter and report on short and long term outcomes. METHODS: A retrospective analysis of all index cases (n = 253) of cryoablation of AVNRT at a single North American institution during the period of 2003-2010 was performed. The majority of cases utilized a 6 mm distal electrode tip catheter. Long term follow up (2.4 ± 1.8 years) was performed via review of the medical record and by questionnaire or telephone if necessary. RESULTS: Acute ablation success was achieved in 93% of cases, with transient conduction defects noted in 39% of cases, and long term conduction defects in 1.6% of cases (4 patients with PR prolongation, 2 of which were permanent). General anesthesia, male gender and presence of structural heart disease were more common in the acute failure cohort. The recurrence rate for AVNRT was 8%. These patients tended to be younger and had more transient A-V conduction defects during the index procedure than those without a recurrence. CONCLUSIONS: In conclusion, anatomic cryoablation of AVNRT utilizing a 6 mm electrode catheter with mapping performed at -80° Celsius is a safe procedure with good long term efficacy. Transient A-V block during the index procedure increases the risk of late recurrence.

The role of empiric superior vena cava isolation in atrial fibrillation: a systematic review and meta-analysis of randomized controlled trials.

BACKGROUND: It is not clear whether additional empiric superior vena cava isolation (SVCI) to pulmonary vein isolation (PVI) results in low recurrences of atrial fibrillation. We aimed to perform a systematic review and meta-analysis of all randomized controlled trials (RCTs) that evaluated role of empiric SVCI in atrial fibrillation ablation. METHODS: We searched PubMed, EMBASE, Cochrane, Scopus, and relevant references for RCTs (inception April 15, 2016 without language restrictions) and performed meta-analysis using random effects model. Recurrence rates of atrial fibrillations, procedural times, fluoroscopic times, and adverse events were the measured outcomes. RESULTS: Three RCTs with a total population of 526 were analyzed. There was no difference in the recurrence rate between PVI plus SVCI versus PVI alone when comparison was made across all types of AF (39 vs 60; odds ratio 0.68; 95 % CI 0.43-1.07; P = 0.73; I 2 = 0 %). When analysis was restricted only to paroxysmal AF, there was a trend towards low recurrence rate in combination group without statistical significance (19 vs 35, OR 0.54; 95 % CI 0.29-1.00; P = 0.05; I 2 = 0). Similarly, no difference was noted between two groups in procedural (weighted mean difference [WMD] 10.12; 95 % CI -9.84 to 30.08; P = 0.32; I 2 = 85 %) and fluoroscopic time (WMD 4.66; 95 % CI -0.92 to 10.25; P = 0.1; I 2 = 94). Adverse events were similar in both groups. CONCLUSION: Empiric SVCI does not provide additional benefit to PVI alone for atrial fibrillation ablation.

Brugada Syndrome Presenting as Polymorphic Ventricular Tachycardia-Ventricular Fibrillation Lasting 94 Seconds Recorded on an Ambulatory Monitor.

IMPORTANCE: Cardiac arrhythmias are common causes of syncope. Brugada syndrome is an uncommon but serious genetic arrhythmia disorder that can be unmasked by medicines causing sodium channel blockade. OBSERVATIONS: This report documents a case of Brugada syndrome and polymorphic ventricular tachycardia-ventricular fibrillation not initially recognized in a patient taking nortriptyline and experiencing syncope. It also illustrates one of the longest episodes of ventricular fibrillation recorded on an ambulatory monitor (94 seconds). Although the baseline electrocardiogram did not demonstrate a typical appearance for Brugada syndrome, provocative testing with flecainide in this patient with documented polymorphic ventricular tachycardia revealed a Brugada electrocardiogram pattern. CONCLUSIONS AND RELEVANCE: Vigilance should be maintained for arrhythmia substrates such as Brugada syndrome in patients with typical symptoms when they are prescribed membrane-active medicines. Long-term ambulatory rhythm monitors can provide useful information in these cases, especially when symptoms are infrequent.

Electrocardiographic patch devices and contemporary wireless cardiac monitoring.

Cardiac electrophysiologic derangements often coexist with disorders of the circulatory system. Capturing and diagnosing arrhythmias and conduction system disease may lead to a change in diagnosis, clinical management and patient outcomes. Standard 12-lead electrocardiogram (ECG), Holter monitors and event recorders have served as useful diagnostic tools over the last few decades. However, their shortcomings are only recently being addressed by emerging technologies. With advances in device miniaturization and wireless technologies, and changing consumer expectations, wearable "on-body" ECG patch devices have evolved to meet contemporary needs. These devices are unobtrusive and easy to use, leading to increased device wear time and diagnostic yield. While becoming the standard for detecting arrhythmias and conduction system disorders in the outpatient setting where continuous ECG monitoring in the short to medium term (days to weeks) is indicated, these cardiac devices and related digital mobile health technologies are reshaping the clinician-patient interface with important implications for future healthcare delivery.

Treatment of anxiety and depression in a patient with brugada syndrome.

Background. Brugada syndrome is rare and has been a clinically diagnosable entity since 1992. Its clinical manifestations are highly variable, and while some patients remain asymptomatic, others endure sudden cardiac death. Initial presenting symptoms may include palpitations, seizures, syncope, and nocturnal agonal respiration. The diagnosis of Brugada syndrome relies on both clinical findings and characteristic ECG patterns that occur spontaneously or are induced by usage of sodium-channel blocking agents. Aims of Case Report. Many psychiatrists may be unaware of the possibility of medical cocontributing etiologies to physical symptoms of anxiety and depression. We present a case of a patient who was treated psychiatrically for anxiety and panic attacks and who was subsequently diagnosed with Brugada syndrome and treated medically with an implantable cardioverter defibrillator (ICD), the only treatment option demonstrated to be effective. Her psychiatric symptoms predated her diagnosis of Brugada syndrome by at least fifteen years. Conclusion. The patient's eventual diagnosis of Brugada syndrome altered the course of her psychopharmacologic medication management and illustrates the utility of a psychosomatic approach to psychiatric symptom management.