Arrhythmia & Electrophysiology Review最新文献

Conduction system pacing (CSP) is a technique of pacing that involves implantation of permanent pacing leads along different sites of the cardiac conduction system and includes His bundle pacing and left bundle branch pacing. There is an emerging role for CSP to achieve cardiac resynchronisation in patients with heart failure with reduced ejection fraction and inter-ventricular dyssynchrony. In this article, the authors review these strategies for resynchronisation and the available data on the use of CSP in overcoming dyssynchrony.

Idiopathic ventricular arrhythmias are ventricular tachycardias or premature ventricular contractions presumably not related to myocardial scar or disorders of ion channels. Of the ventricular arrhythmias (VAs) without underlying structural heart disease, those arising from the ventricular outflow tracts (OTs) are the most common. The right ventricular outflow tract (RVOT) is the most common site of origin for OT-VAs, but these arrhythmias can, less frequently, originate from the left ventricular outflow tract (LVOT). OT-VAs are focal and have characteristic ECG features based on their anatomical origin. Radiofrequency catheter ablation (RFCA) is an effective and safe treatment strategy for OT-VAs. Prediction of the OT-VA origin according to ECG features is an essential part of the preprocedural planning for RFCA procedures. Several ECG criteria have been proposed for differentiating OT site of origin. Unfortunately, the ECG features of RVOT-VAs and LVOT-VAs are similar and could possibly lead to misdiagnosis. The authors review the ECG criteria used in clinical practice to differentiate RVOT-VAs from LVOT-VAs.

Mitral valve prolapse (MVP) is the most common valvular heart disease, affecting 2-3% of the general population. Barlow's disease is a clinical syndrome characterised by MVP. Initially thought a benign condition, MVP is now recognised as a cause of sudden cardiac death and ventricular arrhythmias. The development of new imaging techniques has contributed recently to the identification of novel risk factors. Catheter ablation of ventricular arrhythmias in patients affected by MVP is traditionally considered challenging. In this review, the authors summarise the evidence on arrhythmogenesis in the context of MVP, along with risk stratification of sudden cardiac death and the available treatment options, including new catheter ablation techniques.

Arrhythmogenic right ventricular cardiomyopathy (ARVC), also called arrhythmogenic right ventricular dysplasia or arrhythmogenic cardiomyopathy, is a genetic disease characterised by progressive myocyte loss with replacement by fibrofatty tissue. This structural change leads to the prominent features of ARVC of ventricular arrhythmia and increased risk for sudden cardiac death (SCD). Emphasis should be placed on determining and stratifying the patient's risk of ventricular arrhythmia and SCD. ICDs should be used to treat the former and prevent the latter, but ICDs are not benign interventions. ICDs come with their own complications in this overall young population of patients. This article reviews the literature regarding the factors that contribute to the assessment of risk stratification in ARVC patients.

Post-infarct-related ventricular tachycardia (VT) occurs due to reentry over surviving fibres within ventricular scar tissue. The mapping and ablation of patients in VT remains a challenge when VT is poorly tolerated and in cases in which VT is non-sustained or not inducible. Conventional substrate mapping techniques are limited by the ambiguity of substrate characterisation methods and the variety of mapping tools, which may record signals differently based on their bipolar spacing and electrode size. Real world data suggest that outcomes from VT ablation remain poor in terms of freedom from recurrent therapy using conventional techniques. Functional substrate mapping techniques, such as single extrastimulus protocol mapping, identify regions of unmasked delayed potentials, which, by nature of their dynamic and functional components, may play a critical role in sustaining VT. These methods may improve substrate mapping of VT, potentially making ablation safer and more reproducible, and thereby improving the outcomes. Further large-scale studies are needed.

Rhythm and conduction disturbances and sudden cardiac death are important manifestations of cardiac involvement in autoimmune rheumatic diseases (ARD), which have a serious impact on morbidity and mortality. While the underlying arrhythmogenic mechanisms are multifactorial, myocardial fibrosis plays a pivotal role. It accounts for a substantial portion of cardiac mortality and may manifest as atrial and ventricular arrhythmias, conduction system abnormalities, biventricular cardiac failure or sudden death. In patients with ARD, myocardial fibrosis is considered to be the hallmark of cardiac involvement as a result of inflammatory process or to coronary artery occlusive disease. Myocardial fibrosis constitutes the pathological substrates for reentrant circuits. The presence of supraventricular extra systoles, tachyarrhythmias, ventricular activity and conduction disturbances are not uncommon in patients with ARDs, more often in systemic lupus erythematosus, systemic sclerosis, rheumatoid arthritis, inflammatory muscle disorders and anti-neutrophil cytoplasm antibody-associated vasculitis. In this review, the type, the relative prevalence and the underlying mechanisms of rhythm and conduction disturbances in the emerging field of cardiorheumatology are provided.

Cardiac resynchronisation therapy is an important intervention to reduce mortality and morbidity, but even in carefully selected patients approximately 30% fail to improve. This has led to alternative pacing approaches to improve patient outcomes. Left ventricular (LV) endocardial pacing allows pacing at site-specific locations that enable the operator to avoid myocardial scar and target areas of latest activation. Left bundle branch area pacing (LBBAP) provides a more physiological activation pattern and may allow effective cardiac resynchronisation. This article discusses LV endocardial pacing in detail, including the indications, techniques and outcomes. It discusses LBBAP, its potential benefits over His bundle pacing and procedural outcomes. Finally, it concludes with the future role of endocardial pacing and LBBAP in heart failure patients.