Ashkan Ehdaie

Macroreentrant Loop in Ventricular Tachycardia From the Left Posterior Fascicle: New Implications for Mapping and Ablation

Background—The underlying mechanisms of reentry during left posterior fascicular ventricular tachycardia (LPF-VT) remain unclear. The purpose of this study is to describe the components of LPF-VT reentry circuit and their electrophysiological properties. Methods and Results—Fourteen consecutive patients with LPF-VT underwent electrophysiology study and radiofrequency ablation. Via a multipolar electrode catheter placed from a retrograde aortic approach, a sharp inflection, high-frequency potential (P1) was detected in 9 patients (64%). The ranges of length and velocity of recorded P1 were 9 to 30 mm and 0.5 to 1.2 mm/ms, respectively. Macroreentry involving the ventricular myocardium was confirmed to be the mechanism in all patients by premature ventricular stimuli delivery or entrainment of LPF-VT with progressive fusion, or both. During LPF-VT, the earliest left posterior fascicle (LPF, P2) was considered to be the site of connection between P1 and P2, and the site of the earliest P2 along the left posterior ventricular septum correlated well with the His-ventricular interval during tachycardia. Radiofrequency ablation focused on the P1 potentials (9 patients with a recorded P1) or earliest P2 (5 patients without a recorded P1) was successful in all 14 patients. After 4.5±3.0 months of follow-up, no patients had recurrence of LPF-VT. Conclusions—The LPF-VT macroreentrant loop involves the ventricular myocardium, a part of the LPF, a slow conduction zone, and in certain cases, a specially conducting P1 fiber. The His-ventricular interval during LPF-VT correlates with multiple electrophysiological measures and is a useful marker for identification of the optimal ablation site.

Mechanisms of Posterior Fascicular Tachycardia: The Relationship Between High Frequency Potentials and the Ventricular Myocardium

### Case 1 A 17-year-old man presented with a history of palpitations and surface ECG demonstrating wide QRS tachycardia (QRS duration=140 ms) with a right bundle branch block pattern and left-axis deviation (Figure 1A). The 12-lead ECG was normal during sinus rhythm. Figure 1. A , Surface ECG of tachycardia showed wide QRS complex (QRS duration=140 ms) with a right bundle branch block pattern and left-axis deviation. B , During sinus rhythm (left), A–H and H–V intervals were 57 and 55 ms, respectively. P2 was recorded with an antegrade conduction sequence from proximal to distal multielectrode catheter (MEC). The ventricular potentials at the mid MEC were earlier than proximal and distal ventricular potentials. During tachycardia (right), the H–V interval was −30 ms. P1 and P2 were recorded with opposite conduction sequences with P1 activated antegradely, and P2 activated retrogradely. P1 transition to P2 activation occurred toward the distal MEC. C , Right and left anterior oblique fluoroscopic images of catheter positions. The 20 pole MEC was positioned at the left septal ventricle via a retrograde aortic approach. CS indicates coronary sinus electrogram; HIS, His bundle electrogram; His, His bundle; LAF, left anterior fascicle; LAO, left anterior oblique; LPF, left posterior fascicle; LV, left ventricular electrogram; RAO, right anterior oblique; RB, right bundle; and RV, right ventricular electrogram. See Editor’s Perspective by Asirvatham and Stevenson During electrophysiology study, mapping was performed using a 20 pole multielectrode catheter (MEC) via a retrograde aortic approach (Figure 1C). The baseline A–H and H–V intervals were 57 and 55 ms, respectively (Figure 1B, left). A wide QRS tachycardia identical to the clinical tachycardia was observed with cycle length of 320 ms, H–V interval of −30 ms (Figure 1B, right). This was consistent with a diagnosis of …

Ventricular tachycardia slower than the rate cut-off of a subcutaneous cardiac defibrillator sensed and successfully treated as a result of oversensing

The subcutaneous implantable cardioverter-defibrillator system (S-ICD) has been an important alternative to transvenous defibrillators for certain clinical situations, such as when there is a venous access problem or high risk of bacterial endocarditis. This device reliably detects ventricular tachyarrhythmias and effectively delivers shocks. However, oversensing is more common with the S-ICD compared with transvenous systems. We present a case of a patient in whom a change in the rhythm from sinus rhythm to slow ventricular tachycardia (VT) resulted in reduced R-wave sensing and T- and P-wave oversensing.

Postablation scar-related atrial tachycardia: turning the spotlight on P-wave analysis and window settings.

Left atrial flutter (AFL) and localized scar-related atrial tachycardia (AT) are the most common tachyarrhythmias that follow catheter or surgical ablation for atrial fibrillation. Three-dimensional activation mapping can be challenging due to large and often multiple areas of scar interspersed with areas of delayed conduction, resulting in complex reentrant circuits.1 In our experience, there are 3 components of mapping that are crucial to localizing the re-entry circuit and guiding catheter ablation: (1) analysis of the P wave on surface ECG, (2) right and left atrial (LA) intracardiac activation sequence from multielectrode catheters positioned at the right atrium (RA; 20 poles) and proximal coronary sinus (CS; 10 poles; Figure 1A), and (3) careful attention to the mapping window settings based on P-wave analysis and the cycle length of the tachycardia. Figure 1. A , Right anterior oblique (RAO) and left anterior oblique (LAO) fluoroscopic projections with duodecapolar catheter with 2-10-2 mm spacing placed in the right atrium (RA) at the tricuspid annular and a decapolar catheter with 2-5-2 mm spacing placed in the proximal coronary sinus (CS). B1 , Counter clockwise tricuspid annular atrial flutter (CCW-TA-AFL) with correlation of RA activation and P wave in leads V1, II, III, and aVF. B2 , Counter clockwise mitral annular atrial flutter (CCW-MA-AFL) with simultaneous atrial activation in the RA and CS and earliest RA activation at 9 to 10 pair electrodes indicating early RA activation at the high RA septum. The shallow upsloping portion in leads II, III, and aVF is much earlier than the P-wave onset in V1. B3 , CW-MA-AFL with early RA activation located at the low or mid septum, propagating to high and low RA with atrial activation in the proximal CS preceding the lateral atrial activation of RA. C , Activation mapping of the RA during CCW-TA-AFL. The atrial …

Improving sudden cardiac death risk stratification by evaluating electrocardiographic measures of global electrical heterogeneity and clinical outcomes among patients with implantable cardioverter-defibrillators: rationale and design for a retrospective, multicenter, cohort study

PurposeImplantable cardioverter-defibrillators (ICDs) improve survival of systolic heart failure (HF) patients who are at risk of sudden cardiac death (SCD). We recently showed that electrocardiographic (ECG) global electrical heterogeneity (GEH) is independently associated with SCD in the community-dwelling cohort and developed GEH SCD risk score. The Global Electrical Heterogeneity and Clinical Outcomes (GEHCO) study is a retrospective multicenter cohort designed with two goals: (1) validate an independent association of ECG GEH with sustained ventricular tachyarrhythmias and appropriate ICD therapies and (2) validate GEH ECG risk score for prediction of sustained ventricular tachyarrhythmias and appropriate ICD therapies in systolic HF patients with primary prevention ICD.MethodsAll records of primary prevention ICD recipients with available data for analysis are eligible for inclusion. Records of ICD implantation in patients with inherited channelopathies and cardiomyopathies are excluded. Raw digital 12-lead pre-implant ECGs will be used to measure GEH (spatial QRST angle, spatial ventricular gradient magnitude, azimuth, and elevation, and sum absolute QRST integral). The primary endpoint is defined as a sustained ventricular tachyarrhythmia event with appropriate ICD therapy. All-cause death without preceding sustained ventricular tachyarrhythmia with appropriate ICD therapy will serve as a primary competing outcome. The study will draw data from the academic medical centers.ResultsWe describe the study protocol of the first multicenter retrospective cohort of primary prevention ICD patients with recorded at baseline digital 12-lead ECG.ConclusionFindings from this study will inform future trials to identify patients who are most likely to benefit from primary prevention ICD.Trial registrationURL: http://www.clinicaltrials.gov. Unique identifier: NCT03210883.

Sex Differences in Cardiac Arrhythmias: Clinical and Research Implications

Sex differences have the potential to impact diagnostic and therapeutic interventions in a wide variety of medical conditions, and cardiac arrhythmias are no exception.1 Studies evaluating pathophysiology, disease course, and therapeutic options for cardiac arrhythmias have been performed predominantly in male patients. However, catheter and device-based therapies coupled with landmark clinical trials have contributed to an improved understanding of this important aspect. The objective of this review is to present the current state of knowledge on sex differences in cardiac arrhythmias with a focus on clinical management, while highlighting gaps in knowledge that would benefit from future investigation. ### Atrial Fibrillation and Atrial Flutter #### Disease Burden Atrial fibrillation (AF) and atrial flutter (AFL) are the most commonly encountered tachyarrhythmias in clinical practice, with significant implications for public health and healthcare costs. Stroke, hospitalization, and loss of productivity are the major consequences of AF.2 The incidence of AF (per 1000 person-years) is reported to be between 1.6 and 2.7 in women and between 3.8 and 4.7 in men.2 The age-adjusted incidence and prevalence of AF is lower in women compared with that in men, and accordingly, the lifetime risk of AF from the Framingham Heart Study at 40 years of age was higher in men (26.0% for men versus 23.0% for women).3 Another analysis from the Framingham Heart Study demonstrated no significant sex differences in the risk of developing AFL.4 The prevalence of AF continues to rise among both men and women. In a study investigating the global burden of disease from 1980 to 2010, there was not only an increase in overall burden, incidence, and prevalence of AF, but most importantly an increase in AF-associated mortality in both men and women (Figure 1).5 The age-adjusted mortality for women was consistently higher compared with that for men from 1990 to 2010 (Figure …

Sex Differences in Cardiac Arrhythmias

Cardiac arrhythmias comprise a heterogenous group of disorders ranging from benign premature heart beats to malignant sustained ventricular tachyarrhythmias. Catheter and device-based therapies coupled with landmark clinical trials have enhanced our understanding and treatment of these disorders. Studies evaluating pathophysiology, disease course, and therapeutic options for cardiac arrhythmias have been performed in predominantly male patients. Sex differences have the potential to impact diagnostic and therapeutic interventions in a wide variety of medical conditions and cardiac arrhythmias are no exception. This chapter will review sex differences in different cardiac arrhythmias with an emphasis on clinical evaluation, treatment, and outcomes.

Ryanodine Receptor Mutation in Arrhythmogenic Right Ventricular Cardiomyopathy/Dysplasia: Clinical Implications

This is case of a 40-year-old otherwise healthy and physically active gentleman noted the onset of palpitations while running upstairs the day of admission to the emergency room. On arrival to the emergency room, his heart rate was noted to be 250 beats-per-minute (bpm) and electrocardiogram (ECG) demonstrated ventricular tachycardia (VT). Synchronized electrical cardioversion was performed to sinus bradycardia. He was stabilized and admitted to the hospital. There was demonstration of right ventricular VT with an inferior axis, T-wave inversions in the right precordial leads with a right bundle branch block (RBBB) pattern, epsilon waves, and bidirectional premature ventricular contractions (PVC).

Letter by Ehdaie and Rubin Regarding Article, “Long-Term Arrhythmia-Free Survival in Patients With Severe Left Ventricular Dysfunction and No Inducible Ventricular Tachycardia After Myocardial Infarction”

We read with interest the article by Zaman and colleagues1 regarding use of the electrophysiological study (EPS) to risk stratify patients with an acute ST-segment–elevation myocardial infarction (MI) and reduced left ventricular ejection fraction (LVEF). The study found that a negative EPS at a median of 4 days after ST-segment–elevation MI, in 2 classes of patients who have reduced left ventricular ejection fraction (LVEF ≤30% and ≤35%), defines patients who have a primary end point of survival free of death and arrhythmia equally as good as an untested …