Right ventricular pacing is an independent predictor for ventricular tachycardia/ventricular fibrillation occurrence and heart failure events in patients with an implantable cardioverter-defibrillator

Aims: There is increasing evidence that right ventricular (RV) pacingmay have detrimental effects by increasing morbidity and mortalityfor heart failure in implantable cardioverter–defibrillator(ICD) patients. In this study we prospectively tested the hypothesisthat cumulative RV pacing increases ventricular tachycardia/ventricularfibrillation (VT/VF) occurrence (primary endpoint) and hospitalizationand mortality for heart failure (secondary endpoint) in a predominantlysecondary prophylactic ICD patient population. Methods and results: Two hundred and fifty patients were divided into two groupsaccording to the median of cumulative RV pacing (2 vs. >2%)and prospectively followed-up for occurrence of primary andsecondary endpoints for 18 ± 4 months. Established predictorsfor VT/VF occurrence and heart failure events such as age, leftventricular ejection fraction (EF), QRS duration, history ofatrial fibrillation, and NT-proBNP were collected at enrolment.Multivariate Cox regression analysis revealed that cumulativeRV pacing > 2% and EF < 40% were independent predictorsfor VT/VF occurrence and heart failure events. Kaplan–Meieranalysis showed that patients with >2% cumulative RV pacingmore frequently suffered from VT/VF occurrence and heart failurehospitalization. Conclusion: Cumulative RV pacing > 2% and EF < 40% are independentpredictors for VT/VF occurrence and mortality and hospitalizationfor heart failure in predominantly secondary prophylactic ICDpatients. Our data show that algorithms capable of reducingcumulative RV pacing should be used more frequently in clinicalpractice.     

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。     

主动固定螺旋电极在右室流出道间隔部起搏中的应用体会

目的探索采用主动固定螺旋电极行右室间隔部起搏的临床可行性。方法随机选择54例需要安装双腔起搏器的患者行右室流出道间隔部起搏,将心室起搏螺旋电极先后定位于右室心尖部及右室流出道间隔部并测试起搏参数。结果右室流出道间隔部电极定位成功率为98.15%,该部位起搏参数满足起搏要求,同时起搏的QRS波时限较心尖部变窄(130.45±18.24msvs153.11±20.10ms,P<0.001)。结论采用主动固定螺旋电极行右室流出道间隔部起搏安全性高、可行性好。     

心脏临时起搏支持严重心率缓慢患者的血液净化

目的观察心脏临时起搏对严重心率缓慢患者血液净化的作用。方法7例因各种病因引起的急慢性肾功能衰竭患者伴严重心率缓慢时，经右颈内静脉、左锁骨下静脉途径穿刺置管行气囊电极床边紧急心脏临时起搏，支持血液净化。结果7例中5例行右颈内静脉置管，2例行左锁骨下静脉置管，起搏均成功，效果肯定，起搏时间2～16天，支持血液净化共32次，其中连续性静脉血液滤过（CVVH）2次，8例次行血液透析滤过（HDF），22例次行常规血透（HD），未发现心脏穿孔、气胸、血胸，1例发生导管感染。1例扩张型心肌病患者因低血压心力衰竭不能控制自动出院，其余6例均抢救成功。结论球囊电极床边心脏临时起搏，操作简便快捷，安全有效，可以提高严重心动过缓合并有肾功能不全的重危患者的抢救成功率。     

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     

Influence of heart rate on systolic time intervals: Effects of atrial pacing versus dynamic exercise

The effects of atrial pacing and dynamic exercise in the supine position on systolic time intervals (STI) were compared in 10 normals. In another group of 13 normals, the effect of exercise alone on STI was tested. A linear shortening of electromechanical systole (QS₂) and left ventricular ejection time (LVET) with increasing heart rate was demonstrated with right atrial pacing and dynamic exercise in the frequency range between 60 and 140 beats/min. However, the shortening of LVET was significantly less (p<0.01) with exercise compared to pacing. This is explained by an increase in left ventricular stroke volume with exercise. The pre-ejection period (PEP) was significantly (p<0.001) shortened with exercise, but there was no change with atrial pacing. Thus, changes in heart rate (HR) alone, without changes in the dynamic state of the heart, did not influence PEP. It is suggested that PEP at rest should not be corrected for heart rate. The supine exercise regression equations for correction of heart rate for LVET and PEP differ from both the resting and the upright exercise regression equations. With exercise a frequency correction of STI using regression equations should be abandoned. Instead, uncorrected STI at standard heart rates (e.g., 100, 110, and 130 beats/min) should be taken for comparison. Heart rate standardization should be employed using the formula