美国心脏病学院（ACC）、美国心脏协会（AHA）、美国心律学会（HRS）专家工作组历时1年，于近期联合发布了新版成人室上性心动过速（SVT）指南，全文于2015年9月23日全文刊登在Circulation、Journal of the American College of Cardiology和Heart Rhythm Journal三大重要杂志上。

Acc/aha/hrs 发布新版成人室上性心动过速指南

Genotype-phenotype correlation in the long QT syndrome : Genotype-specific response to sympathetic stimulation

In the past years, cardiovascular mortality has decreased but despite these cardiovascular diseases are responsible for millions of deaths every year in the world and approximately 25% of which are sudden cardiac death (SCD). Implantable defibrillators (ICD) is proven therapy used in primary and secondary SCD prevention. Currently majority of devices use transvenous leads inserted predominantly into the right heart for both pacing and defibrillation. On the other hand, ICD may cause complica­tions, including inappropriate shocks, device-related infection and lead failure. Problems with transvenous leads prompted the development of a subcutaneous defibrillator (S-ICD) with an electrode system that is placed entirely subcutaneously, outside the thoracic cavity. The device may be useful when venous access is difficult, in young patients and in patients at particular risk of infection. S-ICD is not suitable for patients with indications for bradycardia pacing, cardiac resynchronisation therapy and in cases with tachyarrhythmia easily terminated by antitachycardia pacing.

/pdf/subcutaneous-implantable-cardioverter-defibrillator-in-3oogb90kvz.pdf

[Subcutaneous implantable cardioverter-defibrillator in prevention of sudden cardiac death in Poland - opinion paper endorsed by the Polish Cardiac Society Working Group on Heart Rhythm].

Background: Over the last several years the evolution of transvenous implantable cardioverter‑defibrillator (T‑ICD) system and the introduction of subcutaneous ICD (S‑ICD) have contributed to the development of the sudden cardiac death (SCD) prevention in clinical practice. Aims: To report our clinical experience with ICD therapy in children and young adults during the twenty‑ ‑two years of the follow‑up. Methods: We reviewed the database of ICD recipients choosing 80 consecutive patients (pts) implanted at the age of 6–21 in 1996–2018. We analyzed the rate of appropriate (AT) and inappropriate therapies (IT), mortality, complications and new treatment options. Results: A total of 21/80 patients (26.25%) received ≥1 AT for ventricular tachycardia/ventricular fibrillation (anti‑tachycardia pacing or shock) and 25/80 patients (31.25%) had one or multiple IT (P = 0.47). Nine patients (11%) had both AT and IT interventions. During follow‑up, 2 (2.5%) cardiac resynchronization therapy (CRT) systems, and 8 (10%) S‑ICDs were implanted, 3 heart transplantations were performed, and 1 severe tricuspid valve regurgitation occurred. A total of 6/80 patients (7.5%) died. All deaths occurred in the hypertrophic cardiomyopathy group. Conclusions: The mortality rate was 6/80 (7.5%) in the twenty‑two‑year follow‑up. The rate of AT vs. IT was almost equal and remained steady in the long observation period. Severe TR might be a serious clinical problem in some patients. Entirely S‑ICD for SCD prevention is a feasible and safe therapy in young recipients.

/pdf/children-and-young-adults-treated-with-transvenous-and-1w8nek26wj.pdf

Children and young adults treated with transvenous and subcutaneous implantable cardioverter-defibrillators: a 22-year single-center experience and new perspectives

Mutations in hERG (human ether-a-go-go-related gene) potassium channel are closely associated with long QT syndromes. By direct Sanger sequencing, we identified a novel KCNH2 mutation W410R in the patient with long QT syndrome 2 (LQT2). However, the electrophysiological functions of this mutation remain unknown. In comparison to hERGWT channels, hERGW410R channels have markedly decreased total and surface expressions. W410R mutation dramatically reduces hERG channel currents (IKr) and shifts its steady-state activation curve to depolarization. Moreover, hERGW410R channels make dominant-negative effects on hERGWT channels. Significantly, we find hERG channel blocker E-4031 could partially rescue the function of hERGW410R channels by increasing the membrane expression. By using in silico model, we reveal that hERGW410R channels obviously elongate the repolarization of human ventricular myocyte action potentials. Collectively, W410R mutation decreases the currents of hERG channel, because of diminished membrane expression of mutant channels, that subsequently leads to elongated repolarization of cardiomyocyte, which might induce the pathogenesis of LQT2. Furthermore, E-4031 could partially rescue the decreased activity of hERGW410R channels. Thus, our work identifies a novel loss-of-function mutation in KCNH2 gene, which might provide a rational basis for the management of LQT2.

A novel mutation in KCNH2 yields loss-of-function of hERG potassium channel in long QT syndrome 2

Background: Implantable cardioverter-defibrillator (ICD) therapy has been proven effective in the prevention of sudden cardiac death, but data on outcomes of ICD therapy in the young and otherwise healthy patients with long QT syndrome (LQTS) are limited. Aim: We sought to collect data on appropriate and inappropriate ICD discharges, risk factors, and ICD-related complications. Methods: All LQTS patients implanted with an ICD in 14 centres were investigated. Demographic, clinical, and ICD therapy data were collected. Results: The study included 67 patients (88% female). Median age at ICD implantation was 31 years (12–77 years). ICD indication was based on resuscitated cardiac arrest in 46 patients, syncope in 18 patients, and malignant family history in three patients. During a median follow-up of 48 months, 39 (58%) patients received one or more ICD therapies. Time to first appropriate discharge was up to 55 months. Inappropriate therapies were triggered by fast sinus rhythm, atrial fibrillation, and T-wave oversensing. No predictors of inappropriate shocks were identified. Risk factors for appropriate ICD therapy were: (1) recurrent syncope despite b-blocker treatment before ICD implantation, (2) pacemaker therapy before ICD implantation, (3) single-chamber ICD, and (4) noncompliance to b-blockers. In 38 (57%) patients, at least one complication occurred. Conclusions: ICD therapy is effective in nearly half the patient population; however, the rates of early and late complica­tions are high. Although the number of unnecessary ICD shocks and reimplantation procedures may be lowered by modern programming and increased longevity of newer ICD generators, other adverse events are less likely to be reduced.

/pdf/implantable-cardioverter-defibrillators-in-patients-with-225y18hejg.pdf

Ryszard Majcherek

Papers

Implantable cardioverter-defibrillators in patients with long QT syndrome: a multicentre study.