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Ventricular tachycardia [keywords]
- Sudden cardiac arrest in takotsubo cardiomyopathy - a case study. [Journal Article]
- Postepy Kardiol Interwencyjnej 2014; 10(2):110-3.
We present a 59-year-old woman who was admitted to hospital after sudden cardiac arrest due to ventricular fibrillation. Finally takotsubo syndrome was diagnosed. In the acute phase of takotsubo syndrome life-threatening ventricular arrhythmias and significant hemodynamic disorders may occur due to strong adrenergic stimulation and myocardial ischemia. It has been proved that the occurrence of torsade de pointes tachycardia in the acute phase of takotsubo cardiomyopathy is associated with QT prolongation. There are no clear guidelines on pharmacological treatment and implantable cardioverter defibrillator implantation after a past takotsubo episode. Takotsubo cardiomyopathy has not been entirely explained as an etiological disease.
- Optimal Blood Pressure in Patients With Atrial Fibrillation (from the AFFIRM Trial). [JOURNAL ARTICLE]
- Am J Cardiol 2014 Jun 18.
Many medications used to treat atrial fibrillation (AF) also reduce blood pressure (BP). The relation between BP and mortality is unclear in patients with AF. We performed a post hoc analysis of 3,947 participants from the Atrial Fibrillation Follow-Up Investigation of Rhythm Management trial. Systolic blood pressure (SBP) and diastolic blood pressure (DBP) at baseline and follow-up were categorized by 10-mm Hg increments. The end points were all-cause mortality (ACM) and secondary outcome (combination of ACM, ventricular tachycardia and/or fibrillation, pulseless electrical activity, significant bradycardia, stroke, major bleeding, myocardial infarction, and pulmonary embolism). SBP and DBP followed a "U-shaped" curve with respect to primary and secondary outcomes after multivariate analysis. A nonlinear Cox proportional hazards model showed that the incidence of ACM was lowest at 140/78 mm Hg. Subgroup analyses revealed similar U-shaped curves. There was an increased ACM observed with BP <110/60 mm Hg (hazard ratio 2.4, p <0.01, respectively, for SBP and DBP). In conclusion, in patients with AF, U-shaped relation existed between BP and ACM. These data suggest that the optimal BP target in patients with AF may be greater than the general population and that pharmacologic therapy to treat AF may be associated with ACM or adverse events if BP is reduced to <110/60 mm Hg.
- Catheter ablation for premature ventricular contractions and ventricular tachycardia in patients with heart failure. [Journal Article]
- Curr Cardiol Rep 2014 Sep; 16(9):522.
Ventricular arrhythmias (VA) are a significant contributor to morbidity and mortality in patients with heart failure (HF). Implantable cardioverter defibrillators are effective in reducing mortality, but do not prevent arrhythmia recurrence. There is increasing recognition that frequent premature ventricular contractions or repetitive ventricular tachycardia may also lead to new onset ventricular dysfunction or deterioration of ventricular function in patients with pre-existing HF. Suppression of the arrhythmia may lead to recovery of ventricular function. Catheter ablation has emerged as a safe and effective treatment option for reducing arrhythmia recurrence and for suppression of PVCs but its efficacy is governed by the nature of the arrhythmias, the underlying HF substrate and the accessibility of the arrhythmia substrates to ablation.
- Influence of the mode of management of acute myocardial infarction on the inducibility of ventricular tachyarrhythmias with programmed ventricular stimulation after myocardial infarction. [Journal Article]
- Isr Med Assoc J 2014 Jun; 16(6):352-7.
Programmed ventricular stimulation (PVS) is a technique for screening patients at risk for ventricular tachycardia (VT) after myocardial infarction (MI), but the results might be difficult to interpret.To investigate the results of PVS after MI, according to date of completion.PVS results were interpreted according to the mode of MI management in 801 asymptomatic patients: 301 (group I) during the period 1982-1989, 315 (group II) during 1990-1999, and 185 (group III) during 2000-2010. The periods were chosen based on changes in MI management. Angiotensin-converting enzyme (ACE) inhibitors had been given since 1990; primary angioplasty was performed routinely since 2000. The PVS protocol was the same throughout the whole study period.Group III was older (61 +/- 11 years) than groups I (56 +/- 11) and II (58 +/- 11) (P < 0.002). Left ventricular ejection fraction (LVEF) was lower in group III (36.5 +/- 11%) than in groups I (44 +/- 15) and II (41 +/- 12) (P < 0.000). Monomorphic VT < 270 beats/min was induced as frequently in group III (28%) as in group II (22.5%) but more frequently than in group I (20%) (P < 0.03). Ventricular fibrillation and flutter (VF) was induced less frequently in group III (14%) than in groups I (28%) (P < 0.0004) and II (30%) (P < 0.0000). Low left ventricular ejection fraction (LVEF) and date of inclusion (before/after 2000) were predictors of VT or VF induction on multivariate analysis.Induction of non-specific arrhythmias (ventricular flutter and fibrillation) was less frequent than before 2000, despite the indication of PVS in patients with lower LVEF. This decrease could be due to the increased use of systematic primary angioplasty for MI since 2000.
- Ischemic ventricular tachycardia presenting as a narrow complex tachycardia. [Journal Article]
- Indian Pacing Electrophysiol J 2014 Jul; 14(4):203-10.
This report describes a patient presenting with a narrow complex tachycardia in the context of prior myocardial infarction and impaired ventricular function. Electrophysiological studies confirmed ventricular tachycardia and activation and entrainment mapping demonstrated a critical isthmus within an area of scar involving the His-Purkinje system accounting for the narrow QRS morphology. This very rare case shares some similarities with upper septal ventricular tachycardia seen in patients with structurally normal hearts, but to our knowledge has not been seen previously in patients with ischemic heart disease.
- Increased Phosphorylation of Ca(2+) Handling Proteins as a Proarrhythmic Mechanism in Myocarditis. [JOURNAL ARTICLE]
- Circ J 2014 Jul 24.
Background:Because fatal arrhythmia is an important cause of death in patients with myocarditis, we investigated the proarrhythmic mechanisms of experimental autoimmune myocarditis.Methods and Results:Myocarditis was induced by injection of 2 mg porcine cardiac myosin into the footpads of adult Lewis rats on days 1 and 8 (Myo, n=15) and the results compared with Control rats (Control, n=15). In an additional 15 rats, 6 mg/kg prednisolone was injected into the gluteus muscle before the injection of porcine cardiac myosin on days 1 and 8 (MyoS, n=15). Hearts with myocarditis had longer action potential duration (APD), slower conduction velocity (CV; P<0.01 vs. Control), higher CV heterogeneity, greater fibrosis, higher levels of immunoblotting of high-mobility group protein B1, interleukin 6 and tumor necrosis factor-α proteins. Steroid treatment partially reversed the translations for myocarditis, CV heterogeneity, reduced APD at 90% recovery to baseline, increased CV (P<0.01), and reversed fibrosis (P<0.05). Programmed stimulation triggered sustained ventricular tachycardia in Myo rats (n=4/5), but not in controls (n=0/5) or Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) inhibitor (KN93) treated Myo rats (n=0/5, P=0.01). CaMKII autophosphorylation at Thr287 (201%), and RyR2 phosphorylation at Ser2808 (protein kinase A/CaMKII site, 126%) and Ser2814 (CaMKII site, 21%) were increased in rats with myocarditis and reversed by steroid.Conclusions:The myocarditis group had an increased incidence of arrhythmia caused by increased phosphorylation of Ca(2+)handling proteins. These changes were partially reversed by an antiinflammatory treatment and CaMKII inhibition.
- Detection of T-Wave Beat-By-Beat Variations prior to Ventricular Arrhythmias Onset in ICD-Stored Intracardiac Electrograms: The Endocardial T-Wave Alternans Study (ETWAS). [JOURNAL ARTICLE]
- Pacing Clin Electrophysiol 2014 Jul 23.
The aim of the Endocardial T-Wave Alternans Study was to prospectively assess the presence of T-wave alternans (TWA) or beat-to-beat repolarization changes on implantable cardioverter-defibrillator (ICD)-stored electrograms (EGMs) immediately preceding the onset of spontaneous ventricular tachycardia (VT) or fibrillation (VF).Thirty-seven VT/VF episodes were compared to 116 baseline reference EGMs from the same 57 patients. A Bayesian model was used to estimate the T-wave waveform in each cardiac beat and a set of 10 parameters was selected to segment each detected T wave. Beat-by-beat differences in each T-wave parameter were computed using the absolute value of the difference between each beat and the following one. Fisher criterion was used for determining the most discriminant T-wave parameters, then top-M ranked parameters yielding a normalized cumulative Fisher score > 95% were selected, and analysis was applied on these selected parameters. Simulated TWA EGMs were used to validate the algorithm.In the simulation study, TWA was detectable even in the case of the smallest simulated alternans of 25 μV. In 13 of the 37 episodes (35%) occurring in nine of 16 patients, significant larger beat-to-beat variations before arrhythmia onset were detected compared to their respective references (median one positive episode per patient). Parameters including the T-wave apex amplitude seem the more discriminant parameters.Detection of beat-by-beat repolarization variations in ICD-stored EGMs is feasible in a significant subset of cases and may be used for predicting the onset of ventricular arrhythmias.
- The Asymptomatic Wolff-Parkinson-White Patient: Time to be More Proactive? [JOURNAL ARTICLE]
- Circulation 2014 Jul 22.
It is well known by now that sudden cardiac death (SCD) may occur even in the asymptomatic individual with Wolff-Parkinson-White (WPW) pattern(1). This is related to the occurrence of atrial fibrillation (AF) with a rapid ventricular response leading to ventricular fibrillation (VF). The essential and critical risk factor is the presence of an accessory pathway(s) (AP) with critically short antegrade refractoriness. The most common numeric in the literature reflecting this is shortest RR interval between pre-excited cycles <250 ms (SPRRI) in AF. The risk of SCD in the individual with asymptomatic WPW has been estimated to be low, in the range of 0.05-0.2% per year(1), a risk that can obviously be eliminated with successful, uncomplicated catheter ablation. These facts are not in dispute. The controversy that remains is related simply to the fact that population wide electrophysiological assessment and ablation cannot be carried out without risk of complications and even mortality that can mitigate the benefit and broad screening and electrophysiologically based management would be very costly(2). Current guidelines reflect this(3) by suggesting that electrophysiological assessment with a view to ablation is reasonable when a well-informed patient chooses the small risk of ablation over a small risk due to the natural history (2A recommendation) depending on their individual circumstances. Further, there is little advocacy in the guidelines for large-scale population screening. Do we now have evidence to support improved clinical outcomes for electrophysiological assessment with a view to ablation in all individuals with the WPW pattern in the general population?
- CMR-Based Identification of Critical Isthmus Sites of Ischemic and Nonischemic Ventricular Tachycardia. [JOURNAL ARTICLE]
- JACC Cardiovasc Imaging 2014 Jul 9.
This study evaluates whether contrast-enhanced (CE) cardiac magnetic resonance (CMR) can be used to identify critical isthmus sites for ventricular tachycardia (VT) in ischemic and nonischemic heart disease.Fibrosis interspersed with viable myocytes may cause re-entrant VT. CE-CMR has the ability to accurately delineate fibrosis.Patients who underwent VT ablation with CE-CMR integration were included. After the procedure, critical isthmus sites (defined as sites with a ≥11 of 12 pacemap, concealed entrainment, or VT termination during ablation) were projected on CMR-derived 3-dimensional (3D) scar reconstructions. The scar transmurality and signal intensity at all critical isthmus, central isthmus, and exit sites were compared to the average of the entire scar. The distance to >75% transmural scar and to the core-border zone (BZ) transition was calculated. The area within 5 mm of both >75% transmural scar and the core-BZ transition was calculated.In 44 patients (23 ischemic and 21 nonischemic, left ventricular ejection fraction 44 ± 12%), a total of 110 VTs were induced (cycle length 290 ± 67 ms). Critical isthmus sites were identified for 78 VTs (71%) based on ≥11 of 12 pacemaps (67 VTs), concealed entrainment (10 VTs), and/or termination (30 VTs). The critical isthmus sites, and in particular central isthmus sites, had high scar transmurality and signal intensity compared with the average of the entire scar. Of the pacemap, concealed entrainment, and termination sites, 74%, 100%, and 84% were within 5 mm of >75% transmural scar, and 67%, 100%, and 94% were within 5 mm of the core-BZ transition, respectively. The areas within 5 mm of both >75% transmural scar and the core-BZ transition (median 13% of LV) contained all concealed entrainment sites and 77% of termination sites.Both in ischemic and nonischemic VT, critical isthmus sites are typically located in close proximity to the CMR-derived core-BZ transition and to >75% transmural scar. These findings suggest that CMR-derived scar characteristics may guide to critical isthmus sites during VT ablation.