Journal: Circ Arrhythm Electrophysiol

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Abstract

Brugada Syndrome: New Insights From Cardiac Magnetic Resonance and Electroanatomical Imaging.

Pappone C, Santinelli V, Mecarocci V, Tondi L, ... Camporeale A, Lombardi M
Background
Brugada syndrome (BrS) is considered a purely electrical disease with variable electrical substrates. Variable rates of mechanical abnormalities have been also reported. Whether exists a link between electrical and mechanical abnormalities has never been previously explored. This investigational physiopathological study aimed to determine the relationship between the substrate size/location, as exposed by ajmaline provocation, and the severity of mechanical abnormalities, as assessed by cardiac magnetic resonance in patients with BrS.
Methods
Twenty-four consecutive high-risk patients with BrS (mean age, 38±11 years, 17 males), presenting with malignant syncope and documented polymorphic VT/VF, and candidate to implantable cardioverter defibrillator implantation, underwent cardiac magnetic resonance and electroanatomic maps. During each examination, ajmaline test (1 mg/kg over 5 minutes) was performed. Cardiac magnetic resonance findings were compared with 24 age, sex, and body surface area-matched controls. In patients with BrS, the correlation between the electrical substrate extent and right ventricular regional mechanical abnormalities before/after ajmaline challenge was analyzed.
Results
After ajmaline, patients with BrS showed a reduction of right ventricular (RV) ejection fraction (P<0.001), associated with decreased transversal displacement (U, P<0.001) and longitudinal strain (ε, P<0.001) localized at RV outflow tract. In patients with BrS significant preajmaline/postajmaline changes of transversal displacement (ΔU, P<0.001) and longitudinal strain (Δε, P<0.001) were found. In the control group, no mechanical changes were observed after ajmaline. The electrical substrate consistently increased after ajmaline from 1.7±2.8 cm2 to 14.2±7.3 cm2 (P<0.001), extending from the RV outflow tract to the neighboring segments of the RV anterior wall. Postajmaline RV ejection fraction inversely correlated with postajmaline substrate extent (r=-0.830, P<0.001). In patients with BrS and normal controls, cardiac magnetic resonance detected neither myocardial fibrosis nor RV outflow tract morphological abnormalities.
Conclusions
BrS is a dynamic RV electromechanical disease, where functional abnormalities correlate with the maximal extent of the substrate size. These findings open new lights on the physiopathology of the disease.
Registration
URL: https://clinicaltrial.gov; Unique identifier: NCT03524079.



Circ Arrhythm Electrophysiol: 24 Oct 2021:CIRCEP121010004; epub ahead of print
Pappone C, Santinelli V, Mecarocci V, Tondi L, ... Camporeale A, Lombardi M
Circ Arrhythm Electrophysiol: 24 Oct 2021:CIRCEP121010004; epub ahead of print | PMID: 34693720
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Abstract

Implementing Biological Pacemakers: Design Criteria for Successful.

Komosa ER, Wolfson DW, Bressan M, Cho HC, Ogle BM
Each heartbeat that pumps blood throughout the body is initiated by an electrical impulse generated in the sinoatrial node (SAN). However, a number of disease conditions can hamper the ability of the SAN\'s pacemaker cells to generate consistent action potentials and maintain an orderly conduction path, leading to arrhythmias. For symptomatic patients, current treatments rely on implantation of an electronic pacing device. However, complications inherent to the indwelling hardware give pause to categorical use of device therapy for a subset of populations, including pediatric patients or those with temporary pacing needs. Cellular-based biological pacemakers, derived in vitro or in situ, could function as a therapeutic alternative to current electronic pacemakers. Understanding how biological pacemakers measure up to the SAN would facilitate defining and demonstrating its advantages over current treatments. In this review, we discuss recent approaches to creating biological pacemakers and delineate design criteria to guide future progress based on insights from basic biology of the SAN. We emphasize the need for long-term efficacy in vivo via maintenance of relevant proteins, source-sink balance, a niche reflective of the native SAN microenvironment, and chronotropic competence. With a focus on such criteria, combined with delivery methods tailored for disease indications, clinical implementation will be attainable.



Circ Arrhythm Electrophysiol: 29 Sep 2021; 14:e009957
Komosa ER, Wolfson DW, Bressan M, Cho HC, Ogle BM
Circ Arrhythm Electrophysiol: 29 Sep 2021; 14:e009957 | PMID: 34592837
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Abstract

Importance of the Activation Sequence of the His or Right Bundle for Diagnosis of Complex Tachycardia Circuits.

Viswanathan MN, Julie He B, Sung R, Hoffmayer KS, ... Jackman WM, Scheinman MM
In this review, we emphasize the unique value of recording the activation sequence of the His bundle or right bundle branch (RB) for diagnoses of various supraventricular and fascicular tachycardias. A close analysis of the His to RB (H-RB) activation sequence can help differentiate various forms of supraventricular tachycardias, namely atrioventricular nodal reentry tachycardia from concealed nodofascicular tachycardia, a common clinical dilemma. Furthermore, bundle branch reentry tachycardia and fascicular tachycardias often are included in the differential diagnosis of supraventricular tachycardia with aberrancy, and the use of this technique can help the operator make the distinction between supraventricular tachycardias and these other forms of ventricular tachycardias using the His-Purkinje system. We show that this technique is enhanced by the use of multipolar catheters placed to span the proximal His to RB position to record the activation sequence between proximal His potential to the distal RB potential. This allows the operator to fully analyze the activation sequence in sinus rhythm as compared to that during tachycardia and may help target ablation of these arrhythmias. We argue that 3 patterns of H-RB activation are commonly identified-the anterograde H-RB pattern, the retrograde H-RB (right bundle to His bundle) pattern, and the chevron H-RB pattern (simultaneous proximal His and proximal RB activation)-and specific arrhythmias tend to be associated with specific H-RB activation sequences. We show that being able to record and categorize this H-RB relationship can be instrumental to the operator, along with standard pacing maneuvers, to make an arrhythmia diagnosis in complex tachycardia circuits. We highlight the importance of H-RB activation patterns in these complex tachycardias by means of case illustrations from our groups as well as from prior reports.



Circ Arrhythm Electrophysiol: 29 Sep 2021; 14:e009194
Viswanathan MN, Julie He B, Sung R, Hoffmayer KS, ... Jackman WM, Scheinman MM
Circ Arrhythm Electrophysiol: 29 Sep 2021; 14:e009194 | PMID: 34601885
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Abstract

Primer on Pulsed Electrical Field Ablation: Understanding the Benefits and Limitations.

Verma A, Asivatham SJ, Deneke T, Castellvi Q, Neal RE
Pulsed electrical field (PEF) energy is a promising technique for catheter ablation of cardiac arrhythmias. In this article, the key aspects that need to be considered for safe and effective PEF delivery are reviewed, and their impact on clinical feasibility is discussed. The most important benefit of PEF appears to be the ability to kill cells through mechanisms that do not alter stromal proteins, sparing sensitive structures to improve safety, without sacrificing cardiomyocyte ablation efficacy. Many parameters affect PEF treatment outcomes, including pulse intensity, waveform shape, and number of pulses, as well as electrode configuration and geometry. These physical and electrical characteristics must be titrated carefully to balance target tissue effects with collateral implications (muscle contraction, temperature rise, risk of electrical arcing events). It is important to note that any combination of parameters affecting PEF needs to be tested for clinical efficacy and safety. Applying PEF clinically requires knowledge of the fundamentals of this technology to exploit its opportunities and generate viable, durable health improvements for patients.



Circ Arrhythm Electrophysiol: 30 Aug 2021; 14:e010086
Verma A, Asivatham SJ, Deneke T, Castellvi Q, Neal RE
Circ Arrhythm Electrophysiol: 30 Aug 2021; 14:e010086 | PMID: 34538095
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Abstract

Sex Disparities in Sudden Cardiac Death.

Butters A, Arnott C, Sweeting J, Winkel BG, Semsarian C, Ingles J
The overall incidence of sudden cardiac death is considerably lower among women than men, reflecting significant and often under-recognized sex differences. Women are older at time of sudden cardiac death, less likely to have a prior cardiac diagnosis, and less likely to have coronary artery disease identified on postmortem examination. They are more likely to experience their death at home, during sleep, and less likely witnessed. Women are also more likely to present in pulseless electrical activity or systole rather than ventricular fibrillation or ventricular tachycardia. Conversely, women are less likely to receive bystander cardiopulmonary resuscitation or receive cardiac intervention post-arrest. Underpinning sex disparities in sudden cardiac death is a paucity of women recruited to clinical trials, coupled with an overall lack of prespecified sex-disaggregated evidence. Thus, predominantly male-derived data form the basis of clinical guidelines. This review outlines the critical sex differences concerning epidemiology, cause, risk factors, prevention, and outcomes. We propose 4 broad areas of importance to consider: physiological, personal, community, and professional factors.



Circ Arrhythm Electrophysiol: 30 Jul 2021; 14:e009834
Butters A, Arnott C, Sweeting J, Winkel BG, Semsarian C, Ingles J
Circ Arrhythm Electrophysiol: 30 Jul 2021; 14:e009834 | PMID: 34397259
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