[Show abstract][Hide abstract] ABSTRACT: Adenosine is an effective agent for termination of most re-entrant supraventricular arrhythmias involving the atrioventricular node and often also used as a diagnostic agent for wide QRS tachycardias. Adenosine terminates 90–99% of re-entrant supraventricular tachycardias but it may rarely accelerate tachycardias. Adenosine-induced tachycardia acceleration is a rare phenomenon, as only a handful of cases have been described in the literature. We present a case of a 36-year-old man with a narrow complex, short RP tachycardia at a rate of 165 bpm and an initial blood pressure of 110/78 mm Hg. A bolus of 12 mg of adenosine resulted in slowing of the tachycardia to 150 bpm for 2–3 s, followed by acceleration of the tachycardia to 185 bpm that lasted for approximately 20 s and returned to baseline at 165 bpm. The main mechanism of adenosine-induced acceleration may be the secondary sympathetic stimulation, which may be preceded by transient bradycardia and/or hypotension.
[Show abstract][Hide abstract] ABSTRACT: Takotsubo cardiomyopathy (TCM) is generally a reversible cardiomyopathy with a favorable prognosis. Because of a risk of sudden cardiac death (SCD), a wearable cardioverter-defibrillator (WCD) is occasionally prescribed, although its utility is unknown. We reviewed a national database of TCM patients who were prescribed a WCD. The database collected baseline demographics, left ventricular ejection fraction (EF), usage compliance, documented arrhythmias, and final survival status. One-hundred and two patients with mean age 63¡12 years, 11% men, had an initial EF of 27¡7% at the time of WCD prescription. The mean days of use was 44¡31 days, with an average daily hours used of 20¡4 hours. The average follow-up period was 440¡374 days and 95% of patients wore the WCD .90% of prescribed days. Two patients (2%) experienced shocks for ventricular arrhythmias (VAs) and survived; two patients (2%) experienced significant bradyarrhythmias; one patient received two inappropriate shocks due to signal artifact; no patients experienced a detection failure; two patients died during the prescription period: one with asystole, and one while not wearing the WCD; five patients died after discontinuing WCD usage, two of whom had an EF 35% at the time of WCD discontinuation. The WCD was used with a compliance of .90%. The device detected VAs reliably with a low risk of inappropriate shocks. TCM may be associated with a significant risk of death due to tachy-or bradyarrhythmias and the risk of SCD may persist even if the EF improves. KEYWORDS. LifeVest, sudden cardiac death, Takotsubo cardiomyopathy, wearable cardioverter defibrillator. ISSN 2156-3977 (print) ISSN 2156-3993 (online) ' 2014 Innovations in Cardiac Rhythm Management
The Journal of Innovations in Cardiac Rhythm Management. 08/2014; August(2014).
[Show abstract][Hide abstract] ABSTRACT: Upper limit of vulnerability (ULV) testing using T-wave scanning shocks at multiple coupling intervals correlates well with defibrillation threshold (DFT), but remains underutilized in clinical practice. We measured DFT and ULV at a single coupling interval (SCI), with the aim to identify adequate safety margin at a coupling interval that correlates best with DFT.
Consecutive patients undergoing implantable cardioverter defibrillator implantation underwent simultaneous SCI-ULV and DFT assessment. Following a drive train of 400 ms, a T-wave-coupled shock was delivered. To minimize shocks, patients were randomized to programmed shock at 20 ms before peak (Group I), at peak (Group II), or 20 ms after peak (Group III) of T wave. An initial T-wave test shock at 9 J was followed by ±2 J shocks, until SCI-ULV was ascertained. Device rescue shocks were programmed at test shock +2 J and +4 J shocks followed by external rescue shock.
There were 200 patients: 66 patients in Group I, 67 patients each in Groups II and III; mean age was 68.9 ± 12.4 years; 75% of patients men, 66% with ischemic heart disease and mean ejection fraction of 27.1 ± 7.1%. Overall, the mean number of ventricular fibrillation induction was 1.39 ± 0.8, mean SCI-ULV energy was 7.97 ± 3.39 J, and mean DFT was 8.68 ± 3.19 J. The correlation between SCI-ULV and DFT improved from Group I to Group III and was best in Group III (r(2) = 0.689). There were no major adverse events.
SCI-ULV measured 20 ms after the peak of the T wave correlates well with DFT for assessment of adequate safety margin.
Pacing and Clinical Electrophysiology 08/2013; · 1.75 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Sinus arrest rarely occurs during acute myocardial infarction involving the right coronary artery (RCA) and sinus node (SN) artery. We report a rare case of sinus arrest caused by SN artery occlusion following RCA stenting. A 56-year-old woman with a significant history of RCA stenosis with prior bare metal stenting, presented to the emergency department with anginal chest pain. Initial work up showed significant elevation of cardiac troponin T with T-wave inversion in the inferior leads on electrocardiogram (ECG). Coronary angiography revealed a 90% stenosis of midportion of the RCA, mild occlusion in the left anterior descending coronary and left circumflex coronary arteries. Stenting was performed on the RCA lesion. Immediately after undergoing those interventions, thrombosis developed and occluded SN artery. Electrocardiogram showed junctional escape rhythm without P waves at a heart rate of 30 beats per minute, suggesting sinus arrest. The clot in the SN artery was identified and thrombectomy was performed. Neither symptoms nor hypotension were identified during this arrhythmia. Six days later, normal sinus rhythm began to appear on EKG with improving heart rate, and patient still remained completely hemodynamically stable. Pre-discharge exercise stress test had shown 50% predicted heart rate without ST segment change. Sinus node dysfunction is commonly related to degenerative processes, and rarely caused by thrombosis in the SN artery. In our case, we emphasize the potential complication of sinus arrest after RCA stent implantation.
International Archives of Medicine 03/2012; 5(1):11. · 1.08 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Cardiovascular disease accounts for 41% of all-cause mortality in end-stage renal disease (ESRD), with sudden cardiac death (SCD) accounting for two-thirds of these patients. Although implantable cardioverter-defibrillators (ICDs) prevent SCD, little is known about their efficacy in ESRD because such patients have been excluded from major randomized controlled trials (RCTs). Some small, single-center retrospective analyses suggest that ESRD patients may not benefit as much as normal renal function patients whereas other studies suggest the opposite. Given the gaps in our understanding of SCD in ESRD and the clinical equipoise regarding ICD efficacy, an RCT is the next logical step.