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Ventricular tachycardia [keywords]
- Investigation of apoptosis in a canine model of chronic heart failure induced by tachycardia. [Journal Article]
- Acta Physiol Hung 2013 Dec; 100(4):435-44.
Participation of apoptosis during the development of pacing-induced dilated cardiomyopathy is not fully understood. After 7 weeks rapid right ventricular pacing, gene expressions of Bax, Bcl-2 and Caspase-3 were measured by RTQ-PCR from interventricular septum biopsies that were taken weekly in 21 beagle dogs during the development of heart failure. We evaluated protein levels of these genes by Western blot and DNA fragmentation by TUNEL method from autopsy samples. Gene expression of Bax remained unchanged during the pacing period; Bcl-2 mRNA expression transiently decreased in moderate heart failure and their ratio (Bcl-2/Bax) was not significantly altered. Caspase-3 gene expression increased in heart failure. Compared to the control group, expression of Bax and Bcl-2 proteins and their ratio were increased in dogs only after 4 weeks of pacing. No band of activated Caspase was found in the normal nor in the paced myocardium. In the TUNEL assay there was no significant difference between numbers of apoptotic cells in any of the groups, although a few TUNEL-positive cells were detected in the paced groups. Our results are not in favour of apoptosis in the pathogenesis of heart failure in this model and may be it could be attributed to activation of other systems.
- SCN5A mutation in Chinese patients with arrhythmogenic right ventricular dysplasia. [JOURNAL ARTICLE]
- Herz 2013 Dec 8.
Arrhythmogenic right ventricular dysplasia (ARVD) is a genetically determined disorder, characterized by two components: cardiomyopathy and arrhythmia. To date, the ion channel-related pathogenesis underlying this phenomenon has been poorly understood. The aim of this study was to systematically evaluate the sodium channel variants in Chinese patients with ARVD.Patients meeting the diagnostic guidelines of ARVD revised in 2010 were enrolled. All exons and exon-intron boundaries of the SCN5A gene and desmosomal genes known to be associated with ARVD, including DSC2, DSG2, DSP, JUP, and PKP2, were sequenced by direct DNA sequencing. A total of 12 unrelated index patients were included in the study.Eight of the patients developed ventricular tachycardia (VT) and ventricular fibrillation (VF), one of them showed epsilon wave, one of them showed type-1 Brugada wave, seven of them exhibited syncope or dizziness, and none of the patients had a family history of SCD. A new missense heterozygote mutation, I137M, in SCN5A was found in proband 5 with recurrent palpitations and a high incidence of VT. I137M is in exon 4 of SCN5A, at the S1 segment in domain I of Nav1.5, which predicted a substitution of isoleucine for methionine at codon site 137 (p. Ile137Met, I137M). I137M was not detected in 400 healthy control chromosomes from individuals of the same ethnic background, which indicated that this mutation was a conservative site in the SCN5A gene, and the encoded protein Nav1.5 might have a functional defect resulting in arrhythmia.This was the first study to systematically investigate sodium channel variants in Chinese patients with ARVD; a new SCN5A mutation, I137M, was found. This finding may provide new evidence of the genetic pathogenesis of ARVD in Chinese patients, implying that the SCN5A gene should be screened in patients with ARVD and VT/VF.
- Subclinical abnormalities in sarcoplasmic reticulum Ca2+ release promote eccentric myocardial remodeling and pump failure death in response to pressure overload. [JOURNAL ARTICLE]
- J Am Coll Cardiol 2013 Nov 21.
We explored whether subclinical alterations of sarcoplasmic reticulum (SR) Ca(2+) release through cardiac ryanodine receptors (RyR2) aggravate cardiac remodeling in mice carrying a human RyR2(R4496C+/-) gain-of-function mutation in response to pressure overload.RyR2 dysfunction causes increased diastolic SR Ca(2+) release associated with arrhythmias and contractile dysfunction in inherited and acquired cardiac diseases, such as catecholaminergic polymorphic ventricular tachycardia (CPVT) and heart failure (HF).Functional and structural properties of wild-type (WT) and CPVT-associated RyR2(R4496C+/-) hearts were characterized under conditions of pressure overload induced by transverse aortic constriction (TAC).WT and RyR2(R4496C+/-) hearts had comparable structural and functional properties at baseline. After TAC, RyR2(R4496C+/-) hearts responded with eccentric hypertrophy, substantial fibrosis, ventricular dilatation and reduced fractional shortening, ultimately resulting in overt HF. RyR2(R4496C+/-)-TAC cardiomyocytes showed increased incidence of spontaneous SR Ca(2+) release events, reduced Ca(2+) transient peak amplitude and SR Ca(2+) content as well as reduced SR Ca(2+)-ATPase2a and increased Na(+)/Ca(2+)-exchange protein expression. HF phenotype in RyR2(R4496C+/-)-TAC mice was associated with increased mortality due to pump failure, but not tachyarrhythmic events. RyR2-stabilizer K201 markedly reduced Ca(2+) spark frequency in RyR2(R4496C+/-)-TAC cardiomyocytes. Mini-osmotic pump infusion of K201 prevented deleterious remodeling and improved survival in RyR2(R4496C+/-)-TAC mice.The combination of subclinical congenital alteration of SR Ca(2+) release and pressure overload promotes eccentric remodeling and HF death in RyR2(R4496C+/-) mice, and pharmacological RyR2 stabilization prevents this deleterious interaction. These findings imply potential clinical relevance for patients with acquired or inherited gain-of-function of RyR2-mediated SR Ca(2+) release.
- Effectiveness and Safety Beyond 10 Years of Percutaneous Transluminal Septal Ablation in Hypertrophic Obstructive Cardiomyopathy. [JOURNAL ARTICLE]
- Rev Esp Cardiol 2013 Dec 3.
Percutaneous transluminal septal ablation is an alternative treatment in patients with hypertrophic obstructive cardiomyopathy. However, due to the relatively new introduction of this technique, there is no information on its very long term results (>10 years).The present study included consecutive patients treated in 5 centers between 1998 and 2003. We analyzed clinical, hemodynamic, and echocardiographic data at baseline and follow-up.A total of 45 patients were included; there were 31 (69%) women, the mean age was 62.4 (14) years, and 39 patients (86.6%) showed functional class III or IV. Septal thickness was 21.8 (3.5) mm, the peak resting gradient on echocardiography was 77 (39) mmHg, and mitral regurgitation was at least moderate in 22 patients (48.8%). During hospitalization, permanent pacemaker implantation was required in 3 patients and ventricular perforation (by pacing lead) occurred in 1 patient, requiring surgery. After a follow-up of 12.3 years (11.0-13.5 years), 2 patients (4.4%) died from cardiac causes (heart failure and posttransplantation), 3 patients required an implantable cardioverter-defibrillator (1 for primary prevention and 2 due to sustained ventricular tachycardia after cardiac surgery), and 2 underwent cardiac surgery (due to endocarditis and mitral regurgitation). In the last clinical review, functional class was I-II in 39 patients (86.6%) (P<.0001), the peak resting gradient was 16 (23) mmHg (P<.0001), and mitral regurgitation was absent or mild in 34 patients (75.5%) (P<.03).The results of this study suggest that septal ablation is safe and effective in the very long term. The procedure was not associated with a significant incidence of sudden death or symptomatic ventricular arrhythmias. Full English text available from:www.revespcardiol.org/en.
- The Usefulness of T-wave Peak to T-wave End Interval in Identifying Malignant Arrhythmias in Patients with Chagas Disease. [Journal Article]
- Hellenic J Cardiol 2013 Nov-Dec; 54(6):429-34.
Abnormal ventricular repolarization has been proposed as a marker of arrhythmogenesis, and cardiovascular morbidity and mortality. However, little is known about the influence of the interval between the peak and the end of the T wave (Tp-Te) on the inducibility of sustained ventricular arrhythmias (VA) in patients with Chagas disease (CD).Using a case-control design, chagasics undergoing electrophysiological study (EPS) in the last three years were matched by age and sex. Cases represented those with positive EPS and controls those with no inducible VA. Tp-Te>100 ms was considered abnormal. Logistic regression analysis was performed to assess the association between Tp-Te and a positive EPS, after adjusting for confounders.A total of 105 patients (mean age 56 years, 52.4% male) were included: 41 (39%) had a positive EPS; 85.4% with inducible VA (n=35) had non-sustained ventricular tachycardia on the Holter monitoring, compared to 62.5% with negative EPS (n=40, p<0.001). While ventricular aneurysm (adjusted OR=5.3, 95% CI: 1.11-24.96, p=0.03) and coronary artery disease (adjusted OR=8.8, 95% CI: 1.45-53.15, p=0.01) were associated with an increased risk of malignant arrhythmias, a greater ejection fraction (adjusted OR=0.96, 95% CI: 0.93-0.99, p<0.01) was associated with a lower risk of VA. Prolonged Tp-Te trended to be associated with an increased risk of induced VA (p=0.07).Ventricular aneurysm, coronary artery disease, and ejection fraction are associated with inducible VA. Prolonged TP-Te may have a modest role in the identification of patients with CD who are at high risk for VA. Further studies are warranted to validate our results and to correlate them with clinical outcomes.
- Left ventricular strain distribution in healthy dogs and in dogs with tachycardia-induced dilated cardiomyopathy. [JOURNAL ARTICLE]
- Cardiovasc Ultrasound 2013 Dec 5; 11(1):43.
Recently, left ventricular (LV) strain distribution pattern has been assessed in several cardiac disease states. Tachycardia-induced cardiomyopathy (TIC) is an animal model of non-ischemic cardiomyopathy well characterized in terms of global LV dysfunction but with poor understanding of regional variability in LV function. We hypothesized that TIC induces specific changes in LV strain distribution pattern.Twenty five adult mongrel conscious dogs were trained to lie down calmly for echocardiography. In seven selected dogs, we implanted pacing system for TIC induction under general anesthesia. We measured LV geometry and function, strains, and torsion before and after the development of TIC in awake non-sedated state.In 25 healthy dogs, all three types of normal strain significantly increased from base to apex (p <0.05), while a definite and recognizable twist could be measured due to presence of shear strain. In 7 dogs with TIC, marked changes in LV mechanics occurred throughout the cardiac cycle, resulting in decrease of strain (p <0.001), twist (p <0.05), and negative peak twist rate (p <0.05). Interestingly, the relative decrease of strain due to TIC was more pronounced in the apex (p < 0.001), with the radial strain decreasing the most (p < 0.05).TIC is accompanied by decreased systolic LV strain and twist deformation, as well as loss of early diastolic recoil. In addition, the decrease of strain was more profound in the apex. This "reverse" distribution of LV strain may help us understand LV dysfunction in the presence of nonischemic etiology.
- Licorice-induced severe hypokalemia with recurrent torsade de pointes. [Journal Article]
- Ann Noninvasive Electrocardiol 2013 Nov; 18(6):593-6.
A 38-year-old obese woman presented with recurrent polymorphic ventricular tachycardia secondary to persistent hypokalemia necessitating more than 40 DC shocks. All endocrine investigations for hypokalemia were negative with impression of "mysterious hypokalemia." On repeated inquiry, a hidden history of licorice use was elicited causing persistent hypokalemia. The case highlights a life threatening complication of licorice use. In addition, it reiterates the importance of repeated history taking in a patient with undiagnosed hypokalemia and torsade de pointes which avoided a device therapy.
- Pectus Excavatum: Uncommon Electrical Abnormalities Caused By Extrinsic Right Ventricular Compression. [JOURNAL ARTICLE]
- J Cardiovasc Electrophysiol 2013 Dec 4.
We report a case of pectus excavatum associated with ventricular tachycardia provoked by exercise in a 19-year-old man. Although this chest deformity has been associated with supraventricular dysrhythmias, documented ventricular tachycardia has only been reported once. Our patient's ventricular dysrhythmia was treated by surgical correction of his pectus excavatum only, and at 3 years follow-up he has had no recurrence of his ventricular tachycardia. This article is protected by copyright. All rights reserved.
- Risk of sudden cardiac death. [JOURNAL ARTICLE]
- ARYA Atheroscler 2013 Sep; 9(5):274-279.
The aim of this study was to determine characteristics of patients with sudden cardiac arrest (SCA) and/or sudden cardiac death (SCD). We need an effective risk stratification method for SCD in patients without low left ventricular ejection fraction (LVEF).The study population of this cross-sectional study consisted of 241 patients with SCA or SCD who were admitted to an academic hospital, in Tehran, Iran, from 2011 through 2012. SCD was defined as unexpected death from cardiac causes, heralded by abrupt loss of consciousness within one hour of the onset of acute changes in cardiovascular status, or an unobserved death in which the patient was seen and known to be doing well within the previous 24 hours. Survivors of aborted SCD were also included in the study. Clinical and paraclinical characteristics as well as emergency department complications of patients were recorded.The mean age of population was 66.0 ± 16.5 (17 to 90 years). Among the patients, 166 (68.9 %) were male, 50 (20.7%) were smoker, 77 (32.0%) had hypertension, 47 (19.5%) had diabetes mellitus, 21 (8.7%) had hyperlipidemia, and 32 (13.3%) had renal insufficiency. According to New York Health Association (NYHA) functional class, 31 (12.9%) patients were asymptomatic, 42 (17.4) and 99 (41.1%) subjects were in NYHA I and II, respectively and only 69 (28.6%) patients were in NYHA III or IV. In this study, presenting arrhythmia was pulseless electrical activity or asystole which was observed in 130 (53.9%) subjects. Ventricular tachycardia (VT) or ventricular fibrillation (VF) was seen in 53 (22%) patients. Cardiopulmonary resuscitation in emergency room was successful only in 46 (19.1%) subjects.Low ejection fraction (EF) may be an independent predictor of sudden cardiac death in patients, but it is not enough. While implantable cardioverter defibrillators can save lives, we are lacking effective risk stratification and prevention methods for the majority of patients without low EF who will experience SCD.