Long‐Term Nonoutflow Septal Versus Apical Right Ventricular Pacing: Relation to Left Ventricular Dyssynchrony

Background: Right ventricular (RV) apical pacing deteriorates left ventricular (LV) function. RV nonoutflow (low) septal pacing may better preserve ventricular performance, but this has not been systematically tested. Our aim was to assess (1) whether long‐term RV lower septal pacing is superior to RV apical pacing regarding LV volumes and ejection fraction (EF), and (2) if the changes in LV dyssynchrony imposed by pacing are related to the long‐term changes in LV volumes and EF. Methods: In thirty‐six patients with atrioventricular (AV) block, a dual‐chamber pacemaker was implanted. The ventricular electrode was placed either at the apex or at the lower septum, in a randomized sequence. Twenty‐four to 48 hours following implantation, we measured LV volumes, EF, and LV dyssynchrony (by tissue Doppler imaging), both with and without pacing. Patients were reassessed echocardiographically after 12 months. Results: Lower septal pacing induced a more synchronized pattern of LV contraction changes (P < 0.05). Following 12 months, differences were observed between groups regarding LV volumes and EF. EF increased within the septal group (from 52 ± 3.3% to 59 ± 3.0%, P < 0.05). A significant inverse relation was documented between changes in LV dyssynchrony and changes in EF (r =?0.64, P < 0.05). Conclusions: In patients with AV block, RV nonoutflow septal pacing represents an attractive alternative, since it preserves better and may even improve LV volumes and EF. Late changes in EF are associated with the changes in LV dyssynchrony imposed by pacing.     

Is Right Ventricular Outflow Tract Pacing an Alternative to Left Ventricular/Biventricular Pacing?

The right ventricular apex has been used as the traditional pacing site since the development of transvenous pacing in 1959. Some studies suggest that pacing the right ventricular apex may cause remodeling and is harmful. In the past decade, there have been a multitude of studies of the hemodynamic, electrophysiological, electrocardiographic, and clinical effects of ventricular pacing at other sites. Pacing of the left ventricle singly or with biventricular pacing has emerged as an effective and safe therapy for moderate to severe congestive heart failure in patients with prolonged QRS complexes. Studies of alternate right ventricular sites, like the right ventricular outflow tract, have given mixed results. Not all patients can be treated with left ventricular pacing, which is a time-consuming and difficult procedure. Right ventricular pacing is easier and less expensive than left ventricular pacing and further study of additional right ventricular sites seems warranted. (PACE 2004; 27[Pt. II]:871–877)     

A Comparison of Ventricular Function During High Right Ventricular Septal and Apical Pacing after His-Bundle Ablation for Refractory Atrial Fibrillation

This study compares LV performance during high right ventricular septal (RVS) and apical (RVA) pacing in patients with LV dysfunction who underwent His-bundle ablation for chronic AF. We inserted a passive fixation pacing electrode into the RVA and an active fixation electrode in the RVS. A dual chamber, rate responsive pulse generator stimulated the RVA through the ventricular port and the RVS via the atrial port. Patients were randomized to initial RVA (VVIR) or RVS (AAIR) pacing for 2 months. The pacing site was reversed during the next 2 months. At the 2 and 4 month follow-up visit, each patient underwent a transthoracic echocardiographical study and a rest/exercise first pass radionuclide ventriculogram. We studied nine men and three women (mean age of 68 +/- 7 years) with congestive heart failure functional Class (NYHA Classification): I (3 patients), II (7 patients), and III (2 patients). The QRS duration was shorter during RVS stimulation (158 +/- 10 vs 170 +/- 11 ms, P < 0.001). Chronic capture threshold and lead impedance did not significantly differ. LV fractional shortening improved during RVS pacing (0.31 +/- 0.05 vs 0.26 +/- 0.07, P < 0.01). RVS activation increased the resting first pass LV ejection fraction (0.51 +/- 0.14 vs 0.43 +/- 0.10, P < 0.01). No significant difference was observed during RVS and RVA pacing in the exercise time (5.6 +/- 3.2 vs 5.4 +/- 3.1, P = 0.6) or the exercise first pass LV ejection fraction (0.58 +/- 0.15 vs 0.55 +/- 0.16, P = 0.2). The relative changes in QRS duration and LV ejection fraction at both pacing sites showed a significant correlation (P < 0.01). We conclude that RVS pacing produces shorter QRS duration and better chronic LV function than RVA pacing in patients with mild to moderate LV dysfunction and chronic AF after His-bundle ablation.     

Serial Changes in Right Ventricular Apical Pacing Lead Impedance Predict Changes in Left Ventricular Ejection Fraction and Functional Class in Heart Failure Patients

Pacing impedance has been proposed to monitor the clinical status of patients with congestive heart failure (CHF). This study examined whether changes in right ventricular (RV) pacing impedance correlate with changes in left ventricular ejection fraction (LVEF) and New York Heart Association (NYHA) functional class during long-term follow-up in pacemaker recipients with CHF. The study included 67 patients, 70 ± 12 years of age, in NYHA class II or III, and with a mean LVEF = 29 ± 8% at implant. LVEF, NYHA class, and bipolar pacing impedance at the RV outflow tract (RVOT) and apex (RVA) were measured at implant and at 3, 6, 9, and 12 months of follow-up. At implant, impedance was similar in RVOT (548 ± 115 Ω) and RVA (571 ± 174 Ω). Between implant and 3 months, mean impedance decreased (P < 0.0001) at both the RVOT (472 ± 62 Ω) and RVA (488 ± 86 Ω), LVEF increased (43 ± 14%, P < 0.0001), and the NYHA class decreased from 2.4 ± 0.5 to 2.1 ± 0.6 (P = 0.0001). Changes in RVA impedance correlated with changes in LVEF (r = 0.45, P = 0.002). A 50 Ω decrease in RVA impedance corresponded to a 3% decrease in LVEF. RVA impedance decreased significantly as NYHA class increased from I to IV (P = 0.04). There was no correlation between impedance measured at the RVOT and LVEF or NYHA class. A decrease in bipolar pacing impedance at the RVA was associated with worsening LVEF and the NYHA class. The use of pacing impedance to monitor the clinical status in CHF is dependent on the RV pacing site.     

Effect of Right Ventricular Apical Pacing in Survivors of Myocardial Infarction

Background: Much information is available regarding the possible negative effects of long-term right ventricular (RV) apical pacing, which may cause worsening of heart failure. However, very limited data are available regarding the effects of RV pacing in patients with a previous myocardial infarction (MI).
Methods and Results: We screened 115 consecutive post-MI patients and matched a group of 29 pacemaker (PM) recipients with a group of 49 unpaced patients, for age, left ventricular (LV) ejection fraction, and site of MI. During a median follow-up of 54 months, echocardiograms showed a decrease in LV ejection fraction in the paced group, from 51 ± 10 to 39 ± 11 (P < 0.01), and a minimal change in the unpaced group, from 57 ± 8 to 56 ± 7 (P = 0.98). Similar change was observed in systolic and diastolic diameters and volumes.
Conclusions: The study showed that, in post-MI patients, RV apical pacing was associated with a worsening of LV function, suggesting that, among MI survivors, the need for a PM is a marker of worse outcome .     

Right Ventricular Septal Pacing: A Comparative Study of Outflow Tract and Mid Ventricular Sites

Background: Prolonged right ventricle (RV) apical pacing is associated with left ventricle (LV) dysfunction due to dysynchronous ventricular activation and contraction. Alternative RV pacing sites with a narrower QRS compared to RV pacing might reflect a more physiological and synchronous LV activation. The purpose of this study was to compare the QRS morphology, duration, and suitability of RV outflow tract (RVOT) septal and mid‐RV septal pacing. Methods: Seventeen consecutive patients with indication for dual‐chamber pacing were enrolled in the study. Two standard 58‐cm active fixation leads were passed to the RV and positioned in the RVOT septum and mid‐RV septum using a commercially available septal stylet (model 4140, St. Jude Medical, St. Paul, MN, USA). QRS duration, morphology, and pacing parameters were compared at the two sites. The RV lead with less‐satisfactory electrical parameters was withdrawn and deployed in the right atrium. Results: Successful positioning of the pacing leads at the RVOT septum and mid‐RV septum was achieved in 15 patients (88.2%). There were no significant differences in the mean stimulation threshold, R‐wave sensing, and lead impedance between the two sites. The QRS duration in the RVOT septum was 151 ± 14 ms and in the mid‐RV septum 145 ± 13 ms (P = 0.150). Conclusions: This prospective observational study shows that septal pacing can be reliably achieved both in the RVOT and mid‐RV with active fixation leads using a specifically shaped stylet. There are no preferences in regard to acute lead performance or paced QRS duration with either position. (PACE 2010; 33:1169–1173)     

Long‐Term Effects of Upgrading to Biventricular Pacing: Differences with Cardiac Resynchronization Therapy as Primary Indication

Background: Few studies have assessed the long‐term effects of cardiac resynchronization therapy (CRT) in patients with advanced heart failure (HF) and previously right ventricular apical pacing (RVAP). Aims: To assess the clinical and hemodynamic impact of upgrading to biventricular pacing in patients with severe HF and permanent RVAP in comparison with patients who had CRT implantation as initial therapy. Methods and Results: Thirty‐nine patients with RVAP, advanced HF (New York Heart Association [NYHA] III–IV), and severe depression of left ventricular ejection fraction (LVEF) were upgraded to biventricular pacing (group A). Mean duration of RVAP before upgrading was 41.8 ± 13.3 months. Clinical and echocardiographic results were compared to those obtained in a group of 43 patients with left bundle branch block and similar clinical characteristics undergoing “primary” CRT (group B). Mean follow‐up was 35 ± 10 months in patients of group A and 38 ± 12 months in group B. NYHA class significantly improved in groups A and B. LVEF increased from 0.23 ± 0.07 to 0.36 ± 0.09 (P < 0.001) and from 0.26 ± 0.02 to 0.34 ± 0.10 (P < 0.001), respectively. Hospitalizations were reduced by 81% and 77% (P < 0.001). Similar improvements in echocardiographic signs of ventricular desynchronization were also observed. Conclusion: Patients upgraded to CRT exhibit long‐term clinical and hemodynamic benefits that are similar to those observed in patients treated with CRT as initial strategy. (PACE 2010; 841–849)     

Search for the Optimal Right Ventricular Pacing Site: Design and Implementation of Three Randomized Multicenter Clinical Trials

Background: The optimal site to permanently pace the right ventricle (RV) has yet to be determined. To address this issue, three randomized prospective multicenter clinical trials are in progress comparing the long-term effects of RV apical versus septal pacing on left ventricular (LV) function. The three trials are Optimize RV Selective Site Pacing Clinical Trial (Optimize RV), Right Ventricular Apical and High Septal Pacing to Preserve Left Ventricular Function (Protect Pace), and Right Ventricular Apical versus Septal Pacing (RASP).
Methods: Patients that require frequent or continuous ventricular pacing are randomized to RV apical or septal pacing. Optimize RV excludes patients with LV ejection fraction <40% prior to implantation, whereas the other trials include patients regardless of baseline LV systolic function. The RV septal lead is positioned in the mid-septum in Optimize RV, the high septum in Protect Pace, and the mid-septal inflow tract in RASP. Lead position is confirmed by fluoroscopy in two planes and adjudicated by a blinded panel. The combined trials will follow approximately 800 patients for up to 3 years.
Results: The primary outcome in each trial is LV ejection fraction evaluated by radionuclide ventriculography or echocardiography. Secondary outcomes include echo-based measurements of ventricular/atrial remodeling, 6-minute hall walk distance, brain natriuretic peptide levels, and clinical events (atrial tachyarrhythmias, heart failure, stroke, or death).
Conclusion: These selective site ventricular pacing trials should provide evidence of the importance of RV pacing site in the long-term preservation of LV function in patients that require ventricular pacing and help to clarify the optimal RV pacing site.     

右心室不同部位起搏对心脏结构和左心功能的影响

[目的]对比研究右心室不同部位起搏对患者心脏结构和左心功能的影响.[方法]90例Ⅲ度或高度房室传导阻滞患者, 随机分为三组, A组行右室流入道（RVIS）间隔部起搏,B组行右室流出道（RVOT）间隔部起搏,C组行右心室心尖部（RVA）起搏. 观察三组手术中情况,监测术中血流动力学变化及手术曝光时间,比较三组术后随访的起搏器工作情况,心电图QRS波宽度,左心功能及血浆中B型钠尿肽（BNP）的差异.[结果]术中监测血流动力学,A组及B组明显优于C组.术后随访观察,A组及B组心电图QRS波宽度明显窄于C组,A组及B组具有更好的心脏功能.[结论]右心室间隔部起搏无论右室流出道起搏还是右室流入道间隔部起搏都是安全,有效的,比右室心尖部起搏更有利于双心室电激动的同步性,且长期对心脏结构及心功能影响也较少.     

The Long‐Term Outcome of Transcutaneous Electrical Nerve Stimulation in the Treatment for Patients with Chronic Pain: A Randomized,Placebo‐Controlled Trial

Background: Transcutaneous electrical nerve stimulation (TENS) is an easy to use analgesic intervention. However, long‐term randomized placebo‐controlled studies with treatment periods of more than 3 months have not been executed to date. The aim of our study is to explore the long‐term (1 year) time course of the treatment effects of TENS compared to placebo (sham TENS). Method: We performed a randomized placebo‐controlled trial in patients with chronic pain (165), referred to a multidisciplinary pain center of a university hospital. Main outcome measures are the proportion of patients satisfied with treatment result and willing to continue treatment, pain intensity, pain disability, and perceived health status. Results: Survival analysis of time courses of proportions of satisfied patients revealed no significant differences (P = 0.79; log‐rank test) for TENS treatment compared to sham TENS. After 1 year, 30% (24/81) of the patients of the TENS group and 23% (19/82) of the sham TENS group were satisfied with treatment result. These patients experienced a mean overall improvement of 62.7% (n = 43). This effect was not significantly different between both groups. For satisfied patients, there were no differences in pain intensity or disability and perceived health status between the TENS and sham TENS group. Conclusions: Transcutaneous electrical nerve stimulation and sham TENS show similar effects in patients with chronic pain over a period of 1 year. We found support for a long sustained placebo effect.     

阴极经颅直流电刺激改善脑卒中患者上肢功能障碍的系统评价

目的系统评价阴极经颅直流电刺激(c-tDCS)对脑卒中患者上肢功能障碍的康复效果。方法计算机检索Cochrane Central Register of Controlled Trials、PubMed、EMbase、Web of Science、Ovid、中国生物医学文献、中国知网、万方数据和维普数据库中关于c-tDCS改善脑卒中患者上肢功能障碍的随机对照试验,同时检索已纳入文献的参考文献。检索时间从建库至2013 年7 月。2 名独立的研究人员依据Cochrane 协作网推荐的偏倚风险评估方法,对纳入文献的质量进行严格评估及资料提取,对符合标准的随机对照试验进行Meta 合并分析。统计分析采用RevMan 5.1 软件。结果共纳入10 篇。Meta 分析显示,c-tDCS作用于病灶侧初级运动区后,患者的Fugl-Meyer 运动功能量表上肢部分评分与假刺激组相比,差异无统计学意义[WMD=0.11, 95%CI: -5.77~5.99, Z=0.04, P=0.97],c-tDCS 作用于病灶侧初级运动区对患者Jebsen 手功能的作用效果与假刺激组相比,差异无统计学意义[WMD=-1.52, 95%CI: -4.94~1.90, Z=0.87, P=0.38 ]。纳入文献质量的Jadad 评分,低质量2 篇,高质量8 篇。结论目前,没有证据显示c-tDCS比假刺激更有效地改善脑卒中患者上肢运动功能障碍。