Increased Local Sympathetic Nerve Activity During Pathogenesis of Ventricular Arrhythmias Originating from the Right Ventricular Outflow Tract
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BACKGROUND:The contribution of local sympathetic nerves to ventricular arrhythmia (VA) originating from the right ventricular outflow tract (RVOT) has not been elucidated. This study used a canine model to investigate the anatomical changes of the RVOT associated with VA, and the distribution of local sympathetic nerves. MATERIAL AND METHODS:The RVOT-VA canine model (6 dogs) was induced with a circular catheter and high-frequency stimulation (100 Hz) in the middle of the pulmonary artery trunk. Six dogs who were not given stimulation served as the control group. The serum levels of neurotransmitters, the extent of myocardial extension, and the sympathetic nerve density of the RVOT were also analyzed. RESULTS:Ventricular arrhythmias, including premature ventricular contractions, were induced in the experimental group after high-frequency stimulation. Dogs from the RVOT-VA group showed enhanced myocardial extension and sympathetic nerve density in the septal wall as compared with those of the free wall of the RVOT. In the RVOT-VA dogs, serum norepinephrine and neuropeptide Y and the sympathetic nerve density were significantly higher compared with the control group. CONCLUSIONS:Stimulation of the pulmonary artery could activate local sympathetic nerves and enhance myocardial extension, which may be the foundation of RVOT-VA. The RVOT voltage transitional zone positively correlated with myocardial extension, which may serve as an important target for the radiofrequency catheter ablation of RVOT-VA clinically.Keywords:
Ventricular outflow tract
Sympathetic nervous system
Arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) is a genetic cardiomyopathy that most commonly affects young adults. The most commonly observed reason of death in patients suffering from ARVC/D is sudden cardiac death (SCD). On the other hand, idiopathic right ventricular outflow tract tachycardia (RVOT VT) usually has a benign course. Both of the entities may have ventricular tachycardia (VT) with left bundle branch block (LBBB) pattern and inferior axis. We tried to propose new discriminating electrocardiographic indices for differentiation of foretold entities. This was a retrospective study. We reviewed records of patients admitted between 2003 and 2012 with the diagnosis of either ARVC/D or RVOT VT that presented with VT (LBBB morphology). A total of fifty nine patients (30 RVOT VT and 29 ARVC/D) were enrolled. In ARVC/D group, men were dominant while the reverse was true of RVOT VT. Palpitation was more common in the RVOT VT group (90% vs. 66.7%), but aborted SCD and sustained VT were more common in ARVC/D group. The new ECG criteria proposed by us mean QRS duration in V1–V3, QRS difference in right and left precordial leads, S wave upstroke duration, JT interval dispersion, QRS and JT interval of right to left precordial leads were all significantly longer in ARVC/D when compared to RVOT VT patients (p < 0.001). The proposed ECG criteria can be used for non-invasive diagnosis of ARVC/D and incorporation in the future updates of ARVC/D task force criteria.
Ventricular outflow tract
Sinus tachycardia
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Ventricular tachycardia (VT) occurs in the diseased heart as well as in the normal heart but it is not always easy to distinguish. Ventricular tachycardias in the morphologically normal ventricle include idiopahic (fascicular) left ventricular tachycardia and out-flow-tract tachycardia from the right ventricular outflow tract (RVOT) or left ventricular outflow tract (LVOT), whereas VT in diseased heart comprises stable and unstable VT in post-infarction ventricle, VT in dilated cardiomyopathy, VT in arrhythmogenic right ventricular cardiomyopathy, and bundle branch re-entry.
Ventricular outflow tract
Dilated Cardiomyopathy
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Ventricular outflow tract
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Ventricular outflow tract
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Ventricular outflow tract
Precordial examination
Sinus tachycardia
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Abstract Background Radiofrequency catheter ablation (RFCA) has been used for the ablation of premature ventricular contractions (PVCs) or ventricular tachycardia (VT). To date, the mapping and catheter ablation of the arrhythmias originating from the left ventricular outflow tract (LVOT) has not been specified. This study investigates the electrocardiogram (ECG) feature of PVCs or VT originating from the LVOT. Moreover, the treatment outcome of RFCA is analyzed. Methods Mapping and ablation were performed on the supravalvular or subvalvular aorta in 52 cases with PVCs/VT originating from the LVOT. The data were compared with those from 104 patients with PVCs/VT originating from the right ventricular outflow tract (RVOT). A differential procedure was prepared based on the comparison of the ECG features of PVCs/VT originating from the RVOT, LVOT, and their different parts. Results Among 52 cases with PVCs originating from the LVOT, 47 were successfully treated by RFCA, with a success rate of 90.38%. Several differences among the 12-lead ECG features were observed from the RVOT and LVOT in the left and right coronary sinus groups, as well as under the left coronary sinus group (left fibrous trigone): (1) If the precordial leads transition <V3 plus the precordial leads transitional index >0 are considered as the diagnostic parameters of PVCs/VT originating from the LVOT, then the sensitivity, specificity, as well as positive and negative predictive values are 94.12%, 93.00%, 87.27%, and 96.88%, respectively; (2) The analysis of different subgroups of the LVOT are as follows: (a) A mainly positive wave of r or m pattern was recorded in the lead I in 72.73% of patients in the right coronary sinus group, versus 12.90% of patients in the left coronary sinus group, and 0% in the under left coronary sinus group. (b) All patients in the right coronary sinus group presented waves of R II >R III and QS aVR >QS aVL , whereas most patients in the other two groups showed waves of R III >R II and QS aVL >QS aVR . (c) Most patients in the under left coronary sinus group in lead V1 had a mainly positive wave (R) (77.78%), whereas those in the right (81.82%) and left (62.50%) coronary sinus groups had mainly negative waves (rS). Conclusions RFCA is a safe and effective curative therapy for PVCs/VT originating from the LVOT. The 12-lead ECG features of the LVOT from different origins exhibit certain distinctions.
Angiology
Ventricular outflow tract
Radiofrequency catheter ablation
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A 36-year-old woman has suffered from paroxysmal palpitations,chest tightness and shortness of breath for more than 10years.ECG showed broad QRS,ventricular tachycardia and atrioventricular separation.The ECG pointed to an origin in the right ventricular outflow tract.Echocardiography showed that the left ventricular end-diastolic diameter was 53mm and the ejection fraction was 40%.B type natriuretic peptide was 7 920pg/ml.A single radiofrequency application at the site of ectopy was immediately effective.Holter monitoring was normal after ablation.Final diagnosis was right ventricular outflow tract-ventricular tachycardia,tachycardia-induced cardiomyopathy.
Ventricular outflow tract
Palpitations
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Arrhythmogenic right ventricular (RV) cardiomyopathy (ARVC) is associated with ventricular arrhythmias, even without RV structural disease. We aimed to characterize the RV substrate using electroanatomical mapping and to define outcomes following ventricular tachycardia (VT) ablation in patients with and without RV structural abnormalities.Twenty-nine patients with definite or suspected ARVC undergoing VT ablation were classified as 'electrical' and 'structural' cardiomyopathy based on the absence or presence of major structural criteria. Right ventricular (RV) endocardial and epicardial mapping with assessment of bipolar and unipolar voltages, distribution of late potentials (LPs), and inducible VT morphologies were performed. The endpoints for VT ablation were VT non-inducibility and LP abolition. Fourteen patients were categorized as electrical RV cardiomyopathy and 15 were categorized as structural RV cardiomyopathy. In patients with electrical cardiomyopathy, scar was limited to the epicardial surface (epicardium 13 cm2vs. endocardium 1 cm2, P < 0.05), primarily in the outflow tract, whereas patients with structural disease had greater involvement of the endocardium. During a mean follow-up of 22 ± 11 months, the VT recurrence rate was 27%, with LP abolition being a predictor of VT-free survival (HR 0.075 (0.008-0.661), P = 0.020). There was a trend towards higher recurrence rates in structural RV cardiomyopathy (40%) compared with the electrical cardiomyopathy (15%, P = 0.17).The development of RV structural disease in patients with ARVC is associated with extensive epicardial and endocardial scar. Conversely those patients without RV structural disease have identifiable epicardial scar limited to the RV outflow tract. Ventricular tachycardia (VT) ablation in both groups targeting LP abolition is effective in preventing VT recurrence.
Endocardium
Ventricular outflow tract
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Cardiomyopathy Secondary to RVOT VT. Introduction : Several reports describe development of cardiomyopathics secondary to supraventricular tachycardia. Few reports have described cardiomyopathies secondary to ventricular tachycardia. Methods and Results : We describe a patient who presented with dilated cardiomyopathy and repetitive nonsustained monomorphic ventricular tachycardia. Cardiac cathcterization showed hemodynamically insignificant coronary artery disease. Radiofrequency ablation of a right ventricular outflow tract ventricular tachycardia resulted in improvement of the left ventricular systolic function and resolution of heart failure symptoms. Conclusions : This report suggests that right ventricular outflow tract ventricular tachycardia may cause reversible tachycardia‐induced cardiomyopathy.
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Dilated Cardiomyopathy
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