Slow Monomorphic Ventricular Tachycardia Research Articles

PO-04-061 A RARE CASE OF FOCAL LEFT VENTRICULAR OUTFLOW TRACT VENTRICULAR TACHYCARDIA LATE AFTER TRANSCATHETER AORTIC VALVE REPLACEMENT

Transcatheter aortic valve replacement (TAVR) is commonly used to treat severe aortic stenosis (AS). To date there is only one reported case of post-TAVR, new onset, left ventricular outflow tract (LVOT) ventricular tachycardia (VT) which was ablated above the TAVR valve. We report a case of late presenting symptomatic LVOT VT, which was successfully ablated via a trans-septal approach, without fluoroscopy, using intracardiac echocardiography (ICE) and electroanatomic mapping (EAM), thereby, avoiding catheter manipulation in the aorta above the valve. N/A A 68-year-old man underwent TAVR for severe AS with Sapien 3 valve (Edwards Lifescience). Nine months later, the patient developed worsening dyspnea. Echocardiogram showed well seated TAVR valve, and exercise nuclear stress revealed no ischemia. During the stress test, he had slow monomorphic VT at rest, during exercise, and recovery (100-120 bpm). A 24-hour Holter monitor revealed a ventricular arrhythmia burden of 55% with rates between 85 and 112 bpm. The 12-lead ECG of VT had an initial positive deflection in lead I, QS in V1 and V2, and an initial R wave in V3 taller than the sinus QRS, suggesting a septal right ventricular outflow tract (RVOT) vs. LVOT origin. There was no improvement with beta-blocker therapy. An electrophysiology study was performed using ICE and CARTO (Biosense Webster, Diamond Bar, CA). Activation mapping in the septal RVOT revealed a 20ms presystolic electrogram (far field) and an 80% pace map, despite the unipolar signal with QS complex. Radiofrequency ablation performed at this site only mildly suppressed the arrhythmia. The decision was made to map from the LVOT via transseptal access using EAM and real-time markers from Cartosound real time images to accurately visualize the ablation catheter below the TAVR. Earliest activation was beneath the left coronary cusp directly across the RVOT lesions with a sharp 22ms pre-systolic electrogram, unipolar QS, and 90% pace map match. Ablation performed here successfully eliminated the VT even after isoproterenol infusion and programmed stimulation. The patient’s symptoms have resolved, and he remains arrhythmia free. LVOT VA’s may rarely occur post TAVR, although a direct cause cannot be ascertained. This is the first report of successfully ablating the arrhythmia in a TAVR patient using a transeptal, subvalvular approach without fluoroscopy, and avoiding any risks associated with the aortic approach.

Complex and Novel Arrhythmias Precede Stillbirth in Fetuses With De Novo Long QT Syndrome.

Long QT syndrome (LQTS) is a leading cause of sudden cardiac death in early life and has been implicated in ≈10% of sudden infant deaths and unexplained stillbirths. The purpose of our study was to use fetal magnetocardiography to characterize the electrophysiology and rhythm phenotypes of fetuses with de novo and inherited LQTS variants and identify risk factors for sudden death before birth. We reviewed the fetal magnetocardiography database from the University of Wisconsin Biomagnetism Laboratory for fetuses with confirmed LQTS. We assessed waveform intervals, heart rate, and rhythm, including the signature LQTS rhythms: functional 2° atrioventricular block, T-wave alternans, and torsade de pointes (TdP). Thirty-nine fetuses had pathogenic variants in LQTS genes: 27 carried the family variant, 11 had de novo variants, and 1 was indeterminate. De novo variants, especially de novo SCN5A variants, were strongly associated with a severe rhythm phenotype and perinatal death: 9 (82%) showed signature LQTS rhythms, 6 (55%) showed TdP, 5 (45%) were stillborn, and 1 (9%) died in infancy. Those that died exhibited novel fetal rhythms, including atrioventricular block with 3:1 conduction ratio, QRS alternans in 2:1 atrioventricular block, long-cycle length TdP, and slow monomorphic ventricular tachycardia. Premature ventricular contractions were also strongly associated with TdP and perinatal death. Fetuses with familial variants showed a lower incidence of signature LQTS rhythm (6/27=22%), including TdP (3/27=11%). All were live born. The malignancy of de novo LQTS variants was remarkably high and demonstrate that these mutations are a significant cause of stillbirth. Their ability to manifest rhythms not known to be associated with LQTS increases the difficulty of echocardiographic diagnosis and decreases the likelihood that a resultant fetal loss is attributed to LQTS. Registration: URL: http://www.clinicaltrials.gov. Unique identifier: NCT03047161.

P5698What predicts the inefficiency of stellate ganglion block in the treatment of electrical storm?

Abstract Introduction Electrical storm (ES) is an emergent condition which requires a sofisticated approach. Massive sympathetic surge almost always connected with ES precipitates recurrent ventricular arrhythmias. Performing stellate ganglion block (SGB) to alleviate the sympathetic activity on myocardium is becoming a standard of care in many centers. However, there is no clear data to predict in which patients the SGB will be ineffective. Purpose To identify predictors of SGB failure in patients with ES. Methods We analyzed our case series of SGB – the procedure was performed in 31 patients with ES in our center from March 2017 to December 2018. Results Mean left ventricular ejection fraction was 27% (±9%), 74% of patients had ischaemic cardiomyopathy. The most frequent type of arrhythmia was monomorphic ventricular tachycardia (VT), occurring in 71% of patients, followed by polymorphic VT in 13% of cases. After SGB, the burden of ventricular arrhythmias failed to decrease by at least 50% in 10% of cases - these patients were marked as non-responders. Slow monomorphic VT (under 160/min) was observed in all of these patients. On the other hand, fast monomorphic VT or polymorphic VT seemed to respond very well to SGB. We also observed, that patients with ES after acute coronary syndromes were good responders as well. The effect of SGB was not related to age, gender, EF LK or the etiology of cardiomyopathy. Conclusions According to our experience, the failure of SGB in the treatment of ES is not frequent. It typically occurs in patients with slow monomorphic VT. It is probable that such arrhythmias are sustained primarily due to the extensive myocardial substrate, and not because of the sympathetic surge. The situation is quite the opposite in patients with fast VT and acute ischemia.

Guidance of Intra-Operative Ventricular Tachycardia Ablation during LVAD Implantation with Pre-operative Cardiac MRI

Introduction Ventricular tachycardia (VT) is common in ischemic cardiomyopathy (ICM). Ablation maybe required to reduce ICD shocks and improve the quality of life. Preoperative VT mapping is an invasive electrophysiologic study prior to the surgery which heart failure patients may not tolerate. Substrate modification is usually done in an open epicardial approach during LVAD implantation. Non-invasive mapping techniques have not been described before. In this case pre-operative cardiac magnetic resonance (CMR) imaging was used to plan VT scar mapping and guide intra-operative cryoablation that was done while performing LVAD implantation. Case Report 69-year-old man with ICM (ejection fraction of 23%) and biventricular cardioverter-defibrillator (ICD). He has history of VT, four ablations, and on mexiletine and amiodarone. He had VT-related syncope terminated with anti-tachycardia pacing (ATP). ICD interrogation showed 15 appropriate shocks and >100 ATP therapies since the device implantation 6 months prior. In hospital he had slow monomorphic VT (slow cycle length 650 msec) with left bundle-branch morphology and superior axis positive in AVR. Milrinone was started for cardiogenic shock (cardiac index of 1.81 L/min/m2). He was not a transplant candidate so he was scheduled for destination therapy LVAD. Before the procedure he had sustained monomorphic VTs refractory to ATP requiring ICD shock. Cardiac MRI showed large chronic infarct with marked remodeling and transmural delayed enhancement in the inferoseptal, inferior, and inferolateral segments at the base a mid-ventricular portions of the left ventricle (LV) extending into the inferior aspect of the apical LV. Six myocardial segments equivalent was involved with transmural infarct. We decided to do an intra-operative VT ablation during LVAD implantation. Intraoperatively the LVAD ring was anchored to the apex with sutures. LV incision was made, and cryoablation of the inferoseptal towards inferolateral wall was performed using Cryo3 cryoICE catheter. Corresponding to the scar on MRI ablation lesions were created and the lesions were overlapping (from 3 to 9 o'clock position). The incision site was also cryoablated with a total of ten cryoablations. Conclusion This is the first case to use cardiac MRI for preoperative VT mapping and did correspond to the lesions seen intra-operatively. This is a novel non-invasive mapping tool for heart failure patients undergoing surgical cryoablation . At 1 month follow up the patient has had 68 episodes of non-sustained VT, and 8 episodes of VT, successfully treated with ATP.

Entrainment mapping of ventricular tachycardia

A 64-year-old male, with a history of a lateral myocardial infarction, presented with haemodynamically well-tolerated incessant therapy-resistant slow monomorphic ventricular tachycardia (mVT), despite implantable cardioverter defibrillator and antiarrhythmic drugs.

Cardiac rhythm disturbances in children on hemodialysis.

Cardiovascular complications are the leading causes of morbidity and mortality in adult dialysis patients. The aim of this study was to evaluate the cardiovascular system of children on hemodialysis (HD), with special focus on rhythm disturbances. Nine patients, aged 15.6+/-4.1 years, underwent electrocardiographic examination (ECG) including 12-lead ECG, Holter-ECG, QT dispersion, signal-averaged ECG, and exercise testing. Echocardiography and 24-h blood pressure measurement were also performed. Patients had been on HD for a median period of 7 months (range 1-29 months). Normal findings were obtained with 12-lead ECG, exercise testing, QT dispersion, and signal-averaged ECG. Holter-ECG showed short runs of slow monomorphic ventricular tachycardia in two patients. Echocardiography was normal except for ventricular hypertrophy in two patients. In conclusion, rhythm disturbances were rare, with slow monomorphic ventricular tachycardias being the only significant finding. The absence of late potentials and normal QT dispersion suggest that myocardial electrical excitability and recovery are preserved in children on HD.

Safety and efficacy of implantable defibrillator therapy with programmed shock energy at twice the augmented step-down defibrillation threshold: results of the prospective, randomized, multicenter low-energy endotak trial

Whether the safety and efficacy of implantable cardioverter defibrillator (ICD) therapy can be assured with lower output devices is an important question. The purpose of this study was to evaluate whether programming the device output at twice the augmented defibrillation threshold was as safe and effective as using the maximum energy. Patients indicated for ICD therapy, but without slow monomorphic ventricular tachycardia (MVT), who achieved an augmented defibrillation threshold (DFT plus) ≤15 joules (J) with a single endocardial lead system and a biphasic defibrillator were included in the study. Prior to ICD implantation, patients were randomized into 2 groups. The shock energies in test group patients were set as follows: first shock at twice DFT plus, the second to fifth shocks at maximum output (34 J). In control group patients, all shocks were programmed at 34 J. The study population consisted of 166 consecutive patients (mean age 57.4 ± 12.1 years, mean left ventricular ejection fraction 36.8 ± 13.8%). Mean DFT plus was 9.6 ± 3.2 J in test group patients and 10.1 ± 3.5 J in control group patients (p = 0.36). During a mean follow-up of 24.2 ± 9.6 months, 736 arrhythmia episodes were analyzed. The first shock efficacy was 98.3% in the test group patients versus 97.4% in the control group (p = 0.45). Total mortality was 6%, equally distributed in both study groups. The results of this study prove that the method of doubling the defibrillation energy at the DFT plus level provides an adequate safety margin in defibrillator therapy.

Preferential locations for critical reentry circuit sites causing ventricular tachycardia after inferior wall myocardial infarction.

For relatively slow monomorphic ventricular tachycardia (VT) after myocardial infarction, entrainment can be used to identify reentry circuit "isthmus sites" (exit sites and sites proximal to the exit) where radiofrequency (RF) catheter ablation has the greatest likelihood of interrupting reentry. Similarities in coronary and ventricular anatomy may cause such sites to form in preferential locations. The objective of this study is to determine if there are preferential locations for reentry circuit isthmus regions in chronic inferior wall infarctions causing VT. Catheter mapping and RF catheter ablation was performed in 21 patients with an old inferior wall myocardial infarction and VT. The inferior wall was divided into 9 anatomic regions: 3 apical, 3 mid, and 3 basal segments. Of 46 different VTs, an endocardial isthmus site was identified in one or more zones in 28 (61%), with 10 VTs having isthmus sites in two or more adjacent regions. Isthmus zones were found in a basal region of the left ventricle in 24 (86%) of 28 VTs, in a mid segment in 9 (32%) VTs, and in an apical segment in 1 (4%) (P = 0.002). Of 30 RF current applications that terminated VT, 21 (70%) were at basal isthmus sites. The high prevalence of endocardial isthmus zones near the base of the left ventricle suggests that the mitral annulus often plays a role in defining the margins of reentry circuits that cause relatively slow VTs after inferior wall myocardial infarction.

The automatic implantable defibrillator is the most realistic and cost-effective way of preventing sudden cardiac death.

Judgement about cost-effectiveness of medical treatments depends upon the criteria used to define effectiveness. The most rational single criterion is the Quality Adjusted Life Year gained (QALY). Comparisons of cost-effectiveness of treatments may be made by comparing the dollar costs per QALY. Both the dollar and the QALY comparisons are subject to all errors of biological variable measurement and bias introduced by experimental design seen in other biological experiments. The proper methodology for comparison is the prospective randomised controlled clinical trial. Such trials using the automatic implantable defibrillator (AICD) as prophylaxis against sudden cardiac death (SCD) have not yet been performed. The major underlying cause of SCD is coronary artery disease with previous myocardial infarction (MI) and provocative tests for ventricular arrhythmias are the most powerful predictors of SCD in infarction survivors. AICD implantation carriers a mortality of about 2%, and survival after successful implantation is about 89% at one, and 84% at two years. By comparison, infarction survivors with left ventricular ejection fraction < 0.4 and inducible slow monomorphic ventricular tachycardia have a survival rate of 70% at one, and 54% at two years. Antiarrhythmic drugs have not proven effective. There is an urgent need to confirm the advantage of the AICD by proper randomised controlled trial.