Left bundle branch–optimized cardiac resynchronization therapy (LOT-CRT): Results from an international LBBAP collaborative study group

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A Randomized Comparison of Alternative Techniques to Achieve Coronary Sinus Cannulation During Biventricular Implantation Procedures

INTRODUCTION: Biventricular pacing system implantation is a time-consuming and challenging procedure. A critical step in biventricular pacemaker implantation is coronary sinus (CS) cannulation. CS cannulation can be achieved either using dedicated guiding catheters (guiding catheter alone positioning strategy, GCA) or with the aid of an electrophysiology catheter advanced inside the guiding catheter (electrophysiology catheter aided positioning strategy, EPA). AIM OF THE STUDY: To evaluate whether the EPA technique is useful for reducing CS cannulation time compared to a conventional GCA technique. METHODS: Thirty-four consecutive patients were randomly assigned to the GCA (18 patients) or EPA (16 patients) CS cannulation strategy. RESULTS: Time to successful catheterization of CS was 5.0 +/- 2.4 min in the EPA group versus 10.1 +/- 5.4 min in the GCA group p = 0.004. Fluoroscopy time was 4.6 +/- 2.3 min in the EPA group versus 9.2 +/- 4.9 min in the GCA group p = 0.004. Total contrast dye volume to search and engage the CS ostium was 0.0 ml in the EPA group versus 14.3 +/- 3.4 ml in the GCA group p < 0.001. CONCLUSIONS: Cannulation of CS with the adjunct of an electrophysiology catheter to dedicated delivery systems significantly reduces procedural time, fluoroscopy time and contrast dye volume compared to a conventional strategy.     

Dual‐Dye Optical Mapping after Myocardial Infarction: Does the Site of Ventricular Stimulation Alter the Properties of Electrical Propagation?

Introduction: Myocardial infarction (MI) disrupts electrical conduction in affected ventricular areas. We investigated the effect of MI on the regional voltage and calcium (Ca) signals and their propagation properties, with special attention to the effect of the site of ventricular pacing on these properties.
Methods: New Zealand White rabbits were divided into four study groups: sham-operated (C, n = 6), MI with no pacing (MI, n = 7), MI with right ventricular pacing (MI + RV, n = 6), and MI with BIV pacing (MI + BIV, n = 7). At 4 weeks, hearts were excised, perfused, and optically mapped. As previously shown, systolic and diastolic dilation of the LV were prevented by BIV pacing, as was the reduction in LV fractional shortening.
Results: Four weeks after MI, optical mapping revealed markedly reduced action potential amplitudes and conduction velocities (CV) in MI zones, and these increased gradually in the border zone and normal myocardial areas. Also, Ca transients were absent in the infarcted areas and increased gradually 3–5 mm from the border of the normal zone. Neither BIV nor RV pacing affected these findings in any of the MI, border, or normal zones.
Conclusions: MI has profound effects on the regional electrical and Ca signals and on their propagation properties in this rabbit model. The absence of differences in these parameters by study group suggests that altering the properties of myocardial electrical conduction and Ca signaling are unlikely mechanisms by which BIV pacing confers its benefits. Further studies into the regional, cellular, and molecular benefits of BIV pacing are therefore warranted.     

主动固定电极在右室流出道间隔部起搏中的应用研究

目的评价主动固定电极在右室流出道间隔部起搏应用中的可行性和稳定性。方法160例起搏适应证患者随机分为两组,每组80例,一组采用主动固定电极行右室流出道间隔部起搏(简称主动固定电极组),另一组应用被动固定电极行右室心尖起搏(简称被动固定电极组),观察电极置入时间和心电图QRS波宽度,电极置入后随访观察起搏阈值、感知、阻抗,电极脱位及相关并发症。结果主动固定电极组的置入时间和X线曝光时间均长于被动固定电极(26.34±6.54minvs20.86±4.32min,16.78±5.38minvs8.67±4.52min;P均<0.01)。主动固定电极组电极置入15min时较置入即刻的起搏阈值明显下降(0.76±0.21mVvs1.12±0.25mV,P<0.01)。主动固定电极组起搏的QRS波时限较被动固定电极组短(0.14±0.04msvs0.16±0.03ms,P<0.01)。术后随访1,3,6个月,两组的起搏阈值、感知、阻抗均无差异,未见电极脱位等并发症。结论主动固定电极在右室流出道间隔部起搏中的应用是可行和稳定的。     

Electrocardiographic patterns of superior right ventricular outflow tract tachycardias: distinguishing septal and free-wall sites of origin

INTRODUCTION: The superior right ventricular outflow tract (RVOT) septum and free wall are common locations of origin for outflow tract ventricular tachycardias (VT). We hypothesized that (1) unique ECG morphologies of pace maps from septal and free-wall sites in the superior RVOT could be identified using magnetic electroanatomic mapping for accurate anatomical localization; and (2) this ECG information could help facilitate pace mapping and accurate VT localization. METHODS AND RESULTS: In 14 patients with structurally normal hearts who were undergoing ablation for outflow tract VT, a detailed magnetic electroanatomic map of RVOT was constructed in sinus rhythm, then pace mapping was performed from anterior, mid, and posterior sites along the septum and free wall of the superior RVOT. Pace maps were analyzed for ECG morphologies in limb leads and transition patterns in precordial leads. Monophasic R waves in inferior leads for septal sites were taller (1.7 +/- 0.4 mV vs 1.1 +/- 0.3 mV; P < 0.01) and narrower (158 +/- 21 msec vs 168 +/- 15 msec; P < 0.01) compared with free-wall sites; lacked "notching" (28.6% vs 95.2%; P < 0.05); and showed early precordial transition (by lead V4; 78.6% vs 4.8%; P < 0.05). A positive R wave in lead I also distinguished posterior from anterior septal and free-wall sites. Based on QRS morphology in limb leads and precordial transition pattern (early vs late), in a retrospective analysis, a blinded reviewer was able to accurately localize the site of origin of clinical arrhythmia (the successful ablation site on the magnetic electroanatomic map) in 25 of 28 patients (90%) with superior RVOT VT. CONCLUSION: Pace maps in the superior RVOT region manifest site-dependent ECG morphologies that can help in differentiating free-wall from septal locations and posterior from anterior locations. Despite overlap in QRS amplitude and duration, in the majority of patients a combination of ECG features can serve as a useful template in predicting accurately the site of origin of clinical arrhythmias arising from this region.     

右室双部位起搏与双室同步起搏的急性血液动力学对比研究

比较右室双部位 (RV Bi)起搏和双室 (BiV)同步起搏对血液动力学的影响 ,并与右室心尖部 (RVA)、右室流出道 (RVOT)、左室基底部 (LVB)起搏相比较 ,明确双部位起搏是否优于单部位起搏。 15例患者中病窦综合征 8例、Ⅲ度房室阻滞 7例。分别行RVA、RVOT、LVB、RV Bi、BiV起搏 (VVI,6 0～ 90次 /分 ) ,测定心输出量 (CO)和心脏指数(CI)、肺毛细血管嵌顿压 (PCWP)和QRS波时限 (QRSd)。结果 :①与RVA起搏相比 ,RVOT、LVB、RV Bi、BiV起搏CI分别增加了 7.5 %、11.3%、15 .5 %和 17.2 % ,PCWP分别降低了 14.9%、10 .3%、2 1.7%和 2 0 .0 % (P均 <0 .0 1)。②RV Bi、BiV起搏较RVOT、LVB起搏的CO、CI增高而PCWP降低 (P均 <0 .0 5 )。③RV Bi与BiV起搏、RVOT与LVB起搏之间CO、CI和PCWP无显著差异。④RVOT、RV Bi、BiV起搏的QRSd(分别为 12 8± 11,111± 16 ,10 3± 13ms)较RVA起搏 (146± 18ms)时显著缩短 (P≤ 0 .0 0 1) ,而LVB起搏 (142± 15ms)与RVOT、RVA起搏时无显著差异。结论 :RV Bi起搏和BiV同步起搏的急性血液动力学效果无明显差异 ,但双部位起搏的效果明显优于单部位起搏 ;双部位起搏的QRSd也比单部位起搏明显缩短     

Subpectoral implantation of a cardioverter defibrillator under local anaesthesia

Objective—To evaluate patient acceptability of submuscular implantation of a cardioverter defibrillator (ICD) under local anaesthesia with conscious sedation.
Design—Retrospective review. Patient acceptability in the second half of the study was routinely assessed within 24 hours.
Setting—Regional cardiac centre.
Patients—45 consecutive patients with either aborted sudden death or haemodynamically unstable ventricular tachycardia were referred for ICD im- plantation.
Interventions—A subpectoral implantation technique was employed. Twelve procedures were performed under general anaesthesia. Thirty three patients were sedated with midazolam and diamorphine, and local anaesthesia was achieved with bupivicaine. Ventricular fibrillation for defibrillation threshold testing was induced by alternating current, T wave shock, or ultrarapid burst pacing. Patients were contacted after the procedure to assess acceptability.
Results—32 patients having implantation under local anaesthesia did not recall the surgical procedure. One patient described an awareness of "pushing" as the generator was positioned in the pocket. Seven patients said that the procedure was painless but recalled a test shock, four describing it as mildly uncomfortable. All 33 patients stated that they would be willing to have a second implant under local anaesthesia. Twelve patients who had the implant performed under general anaesthesia had no recollection of the procedure. Mean (SD) total procedure duration was significantly longer in those who had general anaesthesia (93 (16) v 67 (17) minutes; p = 0.0009).
Conclusions—Subpectoral implantation of ICDs may be performed safely with patient acceptability under local anaesthesia with conscious sedation.

Keywords: cardioverter defibrillator;  subpectoral implantation;  local anaesthesia;  pacing     

Inducibility of atrial fibrillation during atrioventricular pacing with varying intervals: role of atrial electrophysiology and the autonomic nervous system

INTRODUCTION: Patients receiving VVI pacemakers have a higher incidence of paroxysmal atrial fibrillation (AF) than those receiving DDD pacemakers. However, the mechanism behind the difference is not clear. The purpose of this study was to investigate whether atrial electrophysiology and the autonomic nervous system play a role in the occurrence of AF during AV pacing. METHODS AND RESULTS: The study population consisted of 28 patients who had (group I, n = 15) or did not have (group II, n = 13) AF induced by a single extrastimulus during pacing with different AV intervals. Atrial pressure, atrial size, atrial effective refractory periods, and atrial dispersion were evaluated during pacing with different AV intervals. Twenty-four-hour heart rate variability and baroreflex sensitivity also were examined. Atrial pressure, atrial size, effective refractory periods in the right posterolateral atrium and distal coronary sinus, and atrial dispersion increased as the AV interval shortened from 160 to 0 msec. During AV pacing, group I patients had greater minimal (52+/-17 vs 25+/-7 msec; P < 0.005) and maximal (76+/-16 vs 36+/-9 msec; P < 0.005) atrial dispersion than group II patients. The differences in atrial size and atrial dispersion among different AV intervals were greater in patients with AF than in those without AF. Baroreflex sensitivity (6.6+/-1.7 vs 3.9+/-1.0; P < 0.00005), but not heart rate variability, was higher in patients with AF than in those without AF. CONCLUSION: Abnormal atrial electrophysiology and higher vagal reflex activity can play important roles in the genesis of AF in patients receiving pacemakers.