希氏束起搏进展

希氏束起搏是一种生理性的起搏模式。较传统右心室起搏相比,能够改善电-机械活动的同步性及血流动力学,有较好的临床获益。本文就希氏束起搏的研究进展做一综述。     

Repositioning and extraction of stylet-driven pacing leads with extendable helix used for left bundle branch area pacing

Conventional stylet-driven leads with extendable helix can be implanted successfully for left bundle branch area pacing (LBBAP) with a low acute complication rate. We report two cases in which lead repositioning after a first unsuccessful attempt to LBBAP was associated with fracture of the helix rotating mechanism and failure to fully extract the pacing lead.     

Functional aspects of His bundle physiology and pathophysiology: Clinical implications

In this review we present evidence from many experimental studies which challenge the concept of predestination of His bundle fibers. Using both intra- and extracellular His bundle pacing in the context of atrio-ventricular block and the development of bundle branch blocks these experimental studies provide the underlying mechanisms for the recent clinical findings showing the benefits of permanent His bundle pacing.     

Temporary pacing after His bundle ablation for drug-refractory atrial fibrillation: a risky enterprise?

AIM: In patients with and without a permanent pacemaker His bundle ablation was performed for symptomatic drug-refractory atrial fibrillation. This study was performed to examine the complications of temporary pacing in patients without an already implanted pacemaker. METHODS AND RESULTS: Between January 1996 and December 1998, 152 consecutive patients, both referred and our own (non-referred), underwent His bundle ablation for drug-refractory atrial fibrillation. Primary end-point complications were temporary lead dislodgement requiring immediate repositioning (1), severe arrhythmia (2), death (3) and persistent damage to an already implanted pacing system (4). Secondary end-points were malsensing and malpacing of the temporary lead, and blood vessel problems. Lead dislodgement of the temporary pacemaker occurred in three patients (2.9%), all of whom were in the referred group. Severe arrhythmia and death did not occur. Persistent damage of the already implanted pacing system was not observed. Secondary end-points occurred in 15.8%) of the patients and were successfully managed by a conservative approach. CONCLUSION: Permanent pacemaker implantation is recommended prior to His bundle ablation in order to avoid haemodynamic deterioration due to dislocation of the temporary pacemaker lead. RF current used for His bundle ablation caused no permanent damage to permanent pacing systems.     

Cardiac troponin release following left bundle branch pacing

Left bundle branch pacing (LBBP) has emerged as an alternative to His bundle pacing (HBP) to achieve physiologic ventricular stimulation. The extent of myocardial injury during permanent LBBP implantation is currently not known. The aim of the study was to prospectively assess the extent of myocardial injury during LBBP implantation. Cardiac troponin (cTn) levels were measured at baseline and 6–12 h following permanent LBBP. The number of attempts to achieve LBBP was documented. Troponin levels were measured in a control population undergoing other electrophysiology procedures including HBP, other devices involving right ventricular (RV) pacing, radiofrequency ablation for atrial fibrillation (AF) and supraventricular tachycardia (SVT). Significant elevation of troponin (SET) was defined as threefold increase above the upper reference limit (URL) for cTn. Between December 2019 and April 2020, 204 were prospectively enrolled: LBBP in 98 and Control group 106 (SVT, 55; AF, 20; HBP, 17; other devices, 14). SET (>3× URL) was seen in 49.4% of patients in the LBBP group compared to 58.4% in the control group (p = .23). Peak troponin levels were greater in the control group compared to the LBBP group (230.3 ± 320.1 vs. 87.4 ± 71.3 pg/ml; p = .0001). Compared to LBBP (49.4%), SET was observed less frequently following HBP (17.5%; p = .01), and other device implantation (29%; p = .15). Patients requiring >2 attempts (n = 33) had significantly higher incidence of SET compared to <2 attempts (n = 56; 66.7% vs. 39.3%; p = .01). LBBP implantation is associated with myocardial injury. Asymptomatic troponin release following LBBP is less than or comparable to other interventional electrophysiology procedures.     

希氏束起搏的研究现状和进展

生理性起搏是当前起搏治疗研究的一个热点。长期随访发现右室心尖起搏会导致心脏收缩功能的不同步,导致心功能损伤。希氏束起搏（His bundle pacing,HBP）更接近于生理性起搏,在对心脏功能的改善方面比传统的右室心尖起搏更有优势。本文就 HBP 的研究现状和进展做一综述。     

左束支区域起搏的现状和展望

希氏束和左束支区域的生理性起搏较右室心尖部起搏明显改善心脏的电机械同步性,改善心功能。希氏束起搏是最生理的起搏方式,而且可纠正大部分的完全性左束支传导阻滞,改善心脏再同步化,但也存在起搏阈值高、R波振幅低和潜在的希氏束远端病变风险。左束支呈扇形分布左室间隔内膜面下,起搏阈值和R波振幅同右室心尖部相似,而且左束支近端起搏可纠正病变于希氏束的左束支传导阻滞,可作为心脏再同步化治疗的备选方案。现就左束支的解剖、左束支区域起搏的电生理特点和左束支区域起搏的临床应用进行综述。     

Direct His Bundle and Parahisian Cardiac Pacing

The success rate of direct His bundle pacing (DHBP) and paraHisian pacing has improved remarkably in the last 3–5 years with the advent of dedicated fixation systems that have reduced procedural duration, dislodgement rate, and fluoroscopy time. The methodology of DBHP remains still more complex than paraHisian pacing and is associated with high‐pacing thresholds. Thus, DHBP entails greater battery current drain and reduced device longevity. A shift toward paraHisian pacing (which is fusion pacing of myocardium and His bundle) has occurred because its implementation is easier and the electrical parameters are superior to those of DBHP. Currently, an additional safety lead is inserted at the RV apex or outflow tract to prevent asystole, especially in patients with pure DHBP. It is often possible to avoid a safety lead with paraHisian pacing because ventricular pacing is virtually assured on a long‐term basis via myocardial capture. DBHP and paraHisian pacing can be achieved in a substantial proportion of patients with varying grades of narrow QRS AV block or after AV junctional ablation and in some patients with the ECG manifestation of bundle branch block caused by an intraHisian lesion. Preliminary observations suggest that DHBP may be useful in some patients requiring cardiac resynchronization if it produces a narrow QRS complex because the site of an intraHisian lesion responsible for left bundle branch block is above the site of DHBP.     

His–Purkinje system longitudinal dissociation: From bench to bedside. A case of output-dependent fascicular capture

Introduction : Histological studies reported that the His bundle (HB) is partitioned into narrow cords by collagen running in its long axis, providing the anatomical setting necessary for its longitudinal dissociation. Further confirmations came from the demonstration that direct HB pacing normalizes the QRS axis and duration in subjects with proximal HB lesions causing bundle branch block. However, there is no evidence of the possibility of selective HB partitions pacing destined to the composition of branches and fascicles. Methods and Results : We describe a case of intra-Hisian left bundle branch block in which permanent distal HB pacing corrects left ventricular delay and produces different QRS morphology at different voltage outputs, as an expression of different selective HB compartments recruitment. Conclusion : This case would strengthen the limited data in the literature about HB longitudinal dissociation.     

Right bundle branch pacing: Criteria,characteristics, and outcomes

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Painful left bundle branch block syndrome treated with his bundle pacing

This is a case report of a patient with painful LBBB Syndrome that responded favorably to His Bundle Pacing. This syndrome is largely under recognized despite 50 reports in the literature over the last 60?years. Both diagnosis and treatment are not well defined and represent a major challenge in patients with this entity. Right ventricular pacing has been attempted with inconsistent efficacy outcomes. We report for the first-time complete resolution of chest pain with His bundle pacing. HBP provides a promising alternative pacing option that might provide symptom resolution to patients with a painful LBBB syndrome.     

New‐onset intrinsic and paced QRS morphology of right bundle branch block pattern after atrioventricular nodal ablation: Longitudinal dissociation or anatomical bifurcation?

We performed left bundle pacing combined with atrioventricular nodal (AVN) ablation in a patient with persistent atrial fibrillation and refractory symptomatic heart failure. The major findings were new‐onset intrinsic and paced QRS morphology of right bundle branch block (RBBB) pattern after AVN ablation which was performed at a more atrial site compared with the pacing site and the paced RBBB pattern could not be corrected regardless of the pacing output. Longitudinal dissociation cannot explain this observation, while anatomical separation could. We also confirm this was proximal left bundle pacing rather than His bundle pacing.     

New criterion to determine left bundle branch capture on the basis of individualized His bundle or right ventricular septal pacing

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