Right Ventricular Apical Pacing Research Articles

Functional characteristics of left ventricular synchronization via right ventricular outflow-tract pacing detected by two-dimensional strain echocardiography

BackgroundRecently, due to the detrimental effects on the ventricular function associated with right ventricular apical (RVA) pacing, right ventricular septal (RVS) pacing has become the preferred pacing method. However, the term RVS pacing refers to both right ventricular outflow-tract (RVOT) and mid-septal (RVMS) pacing, leading to a misinterpretation of the results of clinical studies. The purpose of this study, therefore, was to elucidate the functional differences of RVA, RVOT, and RVMS pacing in patients with atrioventricular block. MethodsWe compared the QRS duration, global longitudinal strain (GLS), and left ventricular (LV) synchronization parameters at the three pacing sites in 47 patients. The peak systolic strain (PSS) time delay between the earliest and latest segments among the 18 LV segments and standard deviation (SD) of the time to the PSS were also calculated for the 18 LV segments at each pacing site using two-dimensional (2D) strain echocardiography. ResultsRVMS pacing was associated with a significantly shorter QRS duration compared with RVA and RVOT pacing (154.4±21.4 vs 186.5±19.9 and 171.1±21.5ms, P<0.001). In contrast, RVOT pacing revealed a greater GLS (−14.69±4.92 vs −13.12±4.76 and −13.51±4.81%, P<0.001), shorter PSS time delay between the earliest and latest segments (236.0±87.9 vs 271.3±102.9 and 281.9±126.6%, P=0.007), and shorter SD of the time to the PSS (70.8±23.8 vs 82.7±30.8 and 81.5±33.7ms, P=0.002) compared with RVA and RVMS pacing. ConclusionsThese results suggest that the functional characteristics of RVOT pacing may be a more optimal pacing site than RVMS, regardless of the pacing QRS duration, in patients with atrioventricular conduction disorders.

Triple-site pacing for cardiac resynchronization in permanent atrial fibrillation – Acute phase results from a prospective observational study

Introduction and AimMulti-site pacing is emerging as a new method for improving response to cardiac resynchronization therapy (CRT), but has been little studied, especially in patients with atrial fibrillation. We aimed to assess the effects of triple-site (Tri-V) vs. biventricular (Bi-V) pacing on hemodynamics and QRS duration. MethodsThis was a prospective observational study of patients with permanent atrial fibrillation and ejection fraction <40% undergoing CRT implantation (n=40). One right ventricular (RV) lead was implanted in the apex and another in the right ventricular outflow tract (RVOT) septal wall. A left ventricular (LV) lead was implanted in a conventional venous epicardial position. Cardiac output (using the FloTrac™ Vigileo™ system), mean QRS and ejection fraction were calculated. ResultsMean cardiac output was 4.81±0.97 l/min with Tri-V, 4.68±0.94 l/min with RVOT septal and LV pacing, and 4.68±0.94 l/min with RV apical and LV pacing (p<0.001 for Tri-V vs. both BiV). Mean pre-implantation QRS was 170±25 ms, 123±18 ms with Tri-V, 141±25 ms with RVOT septal pacing and LV pacing and 145±19 with RV apical and LV pacing (p<0.001 for Tri-V vs. both BiV and pre-implantation). Mean ejection fraction was significantly higher with Tri-V (30±11%) vs. Bi-V pacing (28±12% with RVOT septal and LV pacing and 28±11 with RV apical and LV pacing) and pre-implantation (25±8%). ConclusionTri-V pacing produced higher cardiac output and shorter QRS duration than Bi-V pacing. This may have a significant impact on the future of CRT.

Triple-site pacing for cardiac resynchronization in permanent atrial fibrillation – Acute phase results from a prospective observational study

Introduction and AimMulti-site pacing is emerging as a new method for improving response to cardiac resynchronization therapy (CRT), but has been little studied, especially in patients with atrial fibrillation. We aimed to assess the effects of triple-site (Tri-V) vs. biventricular (Bi-V) pacing on hemodynamics and QRS duration. MethodsThis was a prospective observational study of patients with permanent atrial fibrillation and ejection fraction <40% undergoing CRT implantation (n=40). One right ventricular (RV) lead was implanted in the apex and another in the right ventricular outflow tract (RVOT) septal wall. A left ventricular (LV) lead was implanted in a conventional venous epicardial position. Cardiac output (using the FloTrac™ Vigileo™ system), mean QRS and ejection fraction were calculated. ResultsMean cardiac output was 4.81±0.97 l/min with Tri-V, 4.68±0.94 l/min with RVOT septal and LV pacing, and 4.68±0.94 l/min with RV apical and LV pacing (p<0.001 for Tri-V vs. both BiV). Mean pre-implantation QRS was 170±25 ms, 123±18 ms with Tri-V, 141±25 ms with RVOT septal pacing and LV pacing and 145±19 with RV apical and LV pacing (p<0.001 for Tri-V vs. both BiV and pre-implantation). Mean ejection fraction was significantly higher with Tri-V (30±11%) vs. Bi-V pacing (28±12% with RVOT septal and LV pacing and 28±11 with RV apical and LV pacing) and pre-implantation (25±8%). ConclusionTri-V pacing produced higher cardiac output and shorter QRS duration than Bi-V pacing. This may have a significant impact on the future of CRT.

Altered mitochondrial expression genes in patients receiving right ventricular apical pacing

Left ventricular mechanical dyssynchrony from right ventricular apical (RVA) pacing may lead to heart failure. Mitochondrial dysfunction has been observed in the failing heart; however, whether RVA pacing may alter the underlying mitochondrial dynamics at an early stage in patients with preserved ejection fraction is not well understood. RNA was isolated from peripheral whole blood samples of 13 patients. The differentially expressed mRNA profiles from 58 samples (13 experimental subjects; 35 control subjects) were performed using Affymetrix array. Finally, a five-gene signature was identified. DAVID was performed to explore the biological functions of target genes with altered gene expression between two groups. The gene signature (OPA1, CTSA, NDUFA1, STK10 and PRDX1) was able to identify patients post-implant with an area under receiver operating characteristic curve of 0.90 in this study. Our test showed that the gene signature had a sensitivity of 91% with a specificity of 86% in discrimination between post-implant group and healthy controls. In the cellular component category, four genes of the five-gene signature except STK10 were related to mitochondrion. The five-gene signature was associated with oxidative phosphorylation, mitochondrial ATP synthesis and apoptosis in biological process analysis. Pathway analysis indicated that a significant enrichment of candidate genes involved in the calcium signaling and glycosphingolipid biosynthesis pathways. The expression changes observed in this study reflect a profound effect of ventricular mechanical dyssynchrony caused by RVA pacing on the transcriptome at an early stage. RVA pacing alters cellular energy metabolism may have association with mitochondrial dynamics.

Assessment of left ventricular electromechanical activation during right ventricular apical and outflow tract pacing

Abstract Background Right ventricular (RV) apical pacing, induces asynchronous ventricular contraction and impairs cardiac function. Alternative sites of pacing particularly right ventricular outflow tract (RVOT) may have a more favorable hemodynamic profile, physiological left ventricular (LV) activation and normal ventricular contraction pattern. The Aim of the study was to find out the best alternative sites to RV apex for permanent pacemaker (PM) lead fixation in the RVOT, based on the width of the QRS in the surface ECG. Patients and methods The study included 69 patients with pacemaker-dependent complete heart block; 35 with active pacemaker lead fixation in the site which achieved narrowest max. QRS duration in the RVOT (group 1) and 34 with active pacemaker lead fixation in RV apex (group 2). Results High RVOT septum was the site which achieved the narrowest QRS duration on surface ECG (117.86 ± 8.43 ms) when compared with RV apex (140.29 ± 13.14) ( p p p Conclusion High RVOT septum is the ideal site for PM lead implantation. Compared with RV apical pacing, it is associated with improvement in functional and hemodynamic parameters over medium-term follow-up.

Comparison of effectiveness of right ventricular mid-septal pacing vs. apical pacing: a randomized-controlled trials.

The aim of the present study was to compare conventional right ventricular apical pacing (RVAP) with right ventricular mid-septal pacing (RVMSP) in terms of echocardiographic and clinical/biologic features. Ninety-six patients with high-degree atrioventricular block were randomly allocated to RVMSP (n = 50) and RVAP (n = 46). Threshold and impedance, echocardiographic left ventricular ejection fraction, ventricular dyssynchrony features, and distance during a 6-min walk test and Minnesota Living with Heart Failure Questionnaire were determined at 6 and 12 months after pacemaker implantation. Serum levels of N-terminal pro-brain natriuretic peptide were measured. At 6 months of follow-up, echocardiographic and clinical/biologic features showed no significant differences between two groups. The RVAP group had more intraventricular dyssynchrony and a trend towards a worse left ventricular ejection fraction compared with the RVMSP at 12 months of follow-up. However, no overt clinical benefits from RVMSP were found. Right ventricular mid-septal pacing was associated with decreased dyssynchrony and better left ventricular ejection fraction compared with the RVAP. Right ventricular mid-septal pacing could represent an alternative pacing site in selected patients to reduce the harmful effects of traditional RVAP.

Efficacy of biventricular pacing on preventing heart failure in patients with high degree atrioventricular block (BIVPACE-AVB Trial)

To investigate the long-term effect of biventricular (BIV) and right ventricular apical (RVA) pacing on cardiac function in patients with high-degree atrioventricular block (AVB) and left ventricular ejection fraction(LVEF)over 35%. A total of 118 consecutive patients with high-degree AVB in six hospitals from East China between May 2009 and December 2012 were enrolled in this randomized, double-blind and parallel controlled study. Patients were randomly assigned to BIV and RVA pacing with or without LV lead on after one-week cardiac resynchronization therapy (CRT). Cardiac function including New York Heart Association(NYHA), 6 minute walking distance (6MWD), Minnesota living with heart failure (MLHF) score, LVEF, left ventricular end-diastolic volumes/diameters (LVEDV/LVEDD) and other echocardiography parameters, as well as N-terminal pro-B-type natriuretic peptide (NT-proBNP)were assessed at 6 months and 12 months. A total of 114 patients were successfully implanted with CRT. Cardiac function was significantly improved after one-week BIV pacing (n=57) compared with pre-CRT: rate of patients with NYHA Ⅲ (25.44%(29/114) vs. 9.65%(11/114)), MLHF score (17.1±13.6 vs. 26.9±21.6), 6MWD ((315.4±121.8)m vs. (291.8±102.9)m) and NT-proBNP (157.0(70.0, 639.0) ng/L vs. 444.7(144.0, 1 546.0)ng/L, all P<0.05). In BIV group, 6MWD extended from (314.8±142.7)m to (332.7±117.5)m at 6 months (P<0.05), LVEF increased from (60.7±7.9)% at 1 week to (56.6±10.7)% at 6 months(P<0.05), both LVEDV and LVEDD decreased at 12 months compared with at 1 week ((116.2±39.5)ml vs. (131.4±49.6)ml and (50.2±5.6)mm vs. (52.5±6.8)mm, P<0.05). In RVA group (n=57), 6MWD increased at 6 months compared that at 1week ((342.4±109.9)m vs. (310.2±105.1)m, P<0.05), NT-proBNP was higher at 12 months than that at 1 week (349.5(191.8, 884.3)ng/L vs. 127.0(70.3, 336.7)ng/L, P<0.05). Compared with RVA group, BIV group had a bigger shrink in LVEDV decrease at 12 months was more significant in BIV group ((-16.68±24.30)ml vs. (9.09±29.30)ml, P<0.05). Cardiac pacing could acutely improve the cardiac function in patients with high-degree AVB and LVEF over 35%. Improvements on cardiac function and remodeling are more significant after 12-month BIV pacing than that of RVA pacing. Clinical Trail Registry: Chinese Clinical Trial Registry, ChiCTR-TRC-10000832.

Paced QRS fragmentation is associated with spontaneous ventricular fibrillation in patients with Brugada syndrome

Conduction abnormalities are involved in the pathogenesis of ventricular fibrillation (VF) in patients with Brugada syndrome (BrS). We investigated whether right ventricular apical pacing (RVAP) could enhance the conduction abnormality and predict the susceptibility to VF in patients with BrS. Twenty patients with BrS (n = 15) or early repolarization syndrome (ERS) (n = 5) having an implantable cardioverter-defibrillator and 11 patients with complete atrioventricular block having a pacemaker were studied. In BrS, 7 patients had a history of spontaneous VF [VF(+) group] and the remaining 8 did not [VF(-) group]. The number of spikes in fragmented QRS was counted during sinus rhythm and RVAP at rates of 80 and 110 beats/min, respectively. Patients with complete atrioventricular block had no spikes during RVAP. During sinus rhythm, no significant difference was observed in QRS spike numbers among VF(+), VF(-), and ERS groups. During RVAP at 110 beats/min, the sum of spike numbers in leads V1 and V2 increased and the duration of QRS fragmentation increased in the VF(+) group as compared with VF(-) and ERS groups [VF(+): 10.7 ± 3.7, 2.4 ± 3.2, and 2.4 ± 1.8 ms; P < .001; VF(-): 173 ± 32, 45 ± 44, and 49 ± 45 ms; P < .001]. According to the receiver operating characteristic analysis, the cutoff value of the sum of spike numbers in leads V1 and V2 to best discriminate between VF(+) and VF(-) groups was 4 in patients with BrS. RVAP manifested QRS fragmented spikes, which could be associated with spontaneous VF in patients with BrS.

Evaluation of Long Term Effect of RV Apical Pacing on Global LV Function by Echocardiography.

We very often face pacemaker implanted patients during follow-up with shortness of breath and effort intolerance inspite of normal clinical parameters. The aim of our study is to evaluate the cause of effort intolerance and probable cause of sub-clinical Congestive Cardiac Failure (CCF) in a case of long term Right Ventricular (RV) apical pacing on global Left Ventricular (LV) function non- invasively by echocardiography. We studied 54 patients (Male 42, Female 12) of complete heart block (CHB) with RV apical pacing (40 VVI and 14 DCP). Mean duration of pacing was 58+4 months. All patients underwent 24 hours Holter monitoring to determine the percentage of ventricular pacing beats. 2-D Echocardiography was done to assess the regional wall motion of abnormality and global LV ejection fraction by modified Simpson's rule. These methods were coupled with the Doppler derived Myocardial Performance Index (MPI), tissue Doppler imaging, and mechanical regional dyssynchrony with 3-D Echocardiography. Data were analysed from 54 RV- apical paced patients and compared with age and body surface area of 60 controlled subjects (Male 46, Female 14). Evaluation of LV function in 54 patients demonstrated regional wall motion abnormality and Doppler study revealed both LV systolic and diastolic dysfunction compare with control subjects (regional wall motion abnormality 80±6% vs 30±3% with p-value<0.0001) which is proportional to the percentage of ventricular pacing beats (mean paced beat 78%). Global LVEF 50±4% vs 60±2% (p-valve <0.0001) and MPI 0.46 ±0.12 v/s 0.36±0.09 (p-value <0.0001). RV-apical pacing induces iatrogenic electrical dyssynchrony which leads to remodeling of LV and produces mechanical dyssynchrony which is responsible for LV dysfunction. Alternate site of RV pacing and/or biventricular pacing should be done to maintain biventricular electrical synchrony which will preserve the LV function.

Changes in left ventricular global and regional longitudinal strain during right ventricular pacing

Background: LV strain and functions may be altered by Right ventricular apical pacing (RVAP). Right ventricular Septal pacing (RVSP) might be a better alternative. The detrimental effect of RV pacing may be mediated by regional LV impairment. Objectives: Our study aimed to demonstrate the short term impacts of right ventricular (RV) apical and septal pacing on Left ventricular (LV) regional and global longitudinal strain (GLS) in patients with preserved ejection fraction (EF). Methods: 62 patients indicated for permanent pacemaker implantation and preserved LV systolic function were included. Dual chamber pacemakers were implanted in all patients. Patients were divided into 2 groups according to RV lead position: group A (RVAP, n = 32) and group B (RVSP, n = 30). Patients were examined at baseline and after 6 months of implantation for LV systolic functions, global and regional strain by echocardiography and 2D speckle tracking echocardiography. Results: Paced-QRS duration was significantly shorter in group B compared to group A patients (P value 0.02). Regarding ventricular strain, there were no statistically significant difference between both groups at baseline measurements in comparisons of GLS, relative apical longitudinal strain (rALS) and regional longitudinal strain (RLS) (P value of >0.05). In contrast there was statistically significant difference between both groups appeared in results of GLS (P value of 0.01) at 6 months. In addition, regional longitudinal strain in septal, apical and rALS were affected after 6 months with P value of 0.02, 0.03 and 0.03 respectively. Conclusion: RVAP appears to worsen global longitudinal strain more than RVSP, and the resultant decrease in apical strain is most correlated region to decrease in GLS.

Changes in left ventricular global and regional longitudinal strain during right ventricular pacing

Background: LV strain and functions may be altered by Right ventricular apical pacing (RVAP). Right ventricular Septal pacing (RVSP) might be a better alternative. The detrimental effect of RV pacing may be mediated by regional LV impairment. Objectives: Our study aimed to demonstrate the short term impacts of right ventricular (RV) apical and septal pacing on Left ventricular (LV) regional and global longitudinal strain (GLS) in patients with preserved ejection fraction (EF). Methods: 62 patients indicated for permanent pacemaker implantation and preserved LV systolic function were included. Dual chamber pacemakers were implanted in all patients. Patients were divided into 2 groups according to RV lead position: group A (RVAP, n = 32) and group B (RVSP, n = 30). Patients were examined at baseline and after 6 months of implantation for LV systolic functions, global and regional strain by echocardiography and 2D speckle tracking echocardiography. Results: Paced-QRS duration was significantly shorter in group B compared to group A patients (P value 0.02). Regarding ventricular strain, there were no statistically significant difference between both groups at baseline measurements in comparisons of GLS, relative apical longitudinal strain (rALS) and regional longitudinal strain (RLS) (P value of >0.05). In contrast there was statistically significant difference between both groups appeared in results of GLS (P value of 0.01) at 6 months. In addition, regional longitudinal strain in septal, apical and rALS were affected after 6 months with P value of 0.02, 0.03 and 0.03 respectively. Conclusion: RVAP appears to worsen global longitudinal strain more than RVSP, and the resultant decrease in apical strain is most correlated region to decrease in GLS.

Changes in Left Ventricular Global and Regional Longitudinal Strain During Right Ventricular Pacing.

BackgroundOur study aimed to demonstrate the short-term impacts of right ventricular apical pacing (RVAP) and right ventricular septal pacing (RVSP) on left ventricular (LV) regional longitudinal strain (RLS) and global longitudinal strain (GLS) in patients with preserved ejection fraction (EF). LV strain and functions may be altered by RVAP. RVSP might be a better alternative. The detrimental effect of right ventricular (RV) pacing may be mediated by regional LV impairment.MethodsSixty-two patients indicated for permanent pacemaker implantation and preserved LV systolic function were included. Dual chamber pacemakers were implanted in all patients. Patients were divided into two groups according to RV lead position: group A (RVAP, n = 32) and group B (RVSP, n = 30). Patients were examined at baseline and after 6 months of implantation for LV systolic functions, global and regional strain by echocardiography and 2D speckle tracking echocardiography.ResultsPaced QRS duration was significantly shorter in group B compared to group A patients (P = 0.02). Regarding ventricular strain, there was no statistically significant difference between both groups at baseline measurements in comparisons of GLS, relative apical longitudinal strain (rALS) and RLS (P > 0.05). In contrast, there was statistically significant difference between both groups in results of GLS (P = 0.01) at 6 months. In addition, RLSs in septal, apical and rALS were affected after 6 months with P values of 0.02, 0.03 and 0.03, respectively.ConclusionRVAP appears to worsen GLS more than RVSP, and the resultant decrease in apical strain is most correlated region to decrease in GLS.

Abstract 12170: Paced-QRS fragmentation as a Novel Predictor for Ventricular Fibrillation in Patients With Brugada Syndrome

Introduction: In patients with Brugada syndrome, conduction abnormalities could serve as a substrate for ventricular fibrillation (VF) and fragmented QRS appears to be a predictor of VF. Hypothesis: Therefore, we hypothesized that right ventricular apical pacing (RVP) could enhance or unmask the QRS fragmentation in the right precordial leads and paced-QRS fragmentation might predict a risk of VF in patients with Brugada syndrome. Methods: Eighteen consecutive male patients who underwent ICD implantation were categorized into 10 patients with spontaneous VF (group VF(+)) and 8 patients without VF (group VF(-)). The number of spikes within the QRS complex in leads V1-V2 and the duration of QRS fragmentation in lead V1 were evaluated (with 0.05-150 Hz filters) during both sinus rhythm (SR) and during RVP using ICD at VVI 80 bpm or 110 bpm. Results: Sum of spikes in lead V1-V2 was not significantly different between groups VF(+) and VF(-) during SR; however, it was greater in VF(+) than VF(-) during RVP at VVI 80 bpm (7.0±2.8 vs 2.9±5.2, p = 0.04) and VVI 110 bpm (10.7±3.7 vs 2.4±3.2, p = 0.01). The duration of QRS fragmentation in lead V1 was longer in VF(+) than VF(-) at VVI 110 bpm (173±32 ms vs 45±44 ms, p = 0.006). In VF(+), sum of spikes (V1-V2) was higher and the duration of QRS fragmentation (V1) was longer at VVI 110 bpm compared to VVI 80 bpm (10.1±3.7 vs 7.0±2.8, p = 0.02 and 173±32 ms vs 111±39 ms, p = 0.02, respectively). According to ROC analysis, sum of spikes ≥ 3.5 most accurately predicted spontaneous VF with sensitivity of 100% and specificity of 87.5%. Conclusions: Right ventricular apical pacing enhanced or unmasked QRS fragmentation in the right precordial leads in patients with Brugada syndrome. Therefore, paced-QRS fragmentation could be a novel predictor for spontaneous VF in patients with Brugada Syndrome.

Deterioration of left ventricular systolic function in extended Pacing to Avoid Cardiac Enlargement (PACE) trial: the predictive value of early systolic dyssynchrony.

Biventricular (BiV) pacing was superior to right ventricular apical (RVA) pacing at extended follow-up in the Pacing to Avoid Cardiac Enlargement (PACE) trial. Early pacing-induced systolic dyssynchrony (DYS) might be related to mid-term result. However, it remains unknown whether early pacing-induced DYS can predict long-term reduction of left ventricular (LV) systolic function. Patients with standard pacing indications and normal LV ejection fraction (LVEF) were randomized either to BiV (n = 89) or RVA (n = 88) pacing. Seventy-four patients in the RVA group and 72 in the BiV pacing group completed follow-up longer than 2 years. Serial echocardiography was performed with DYS assessed by tissue Doppler imaging, and the early pacing-induced DYS was defined as >33 ms by using standard deviation of the time to peak systolic velocity (Dyssynchrony Index) in a 12-segment model of LV at 1 month. There were 46 (32%) patients having early pacing-induced DYS that was more prevalent in the RVA pacing group than that in the BiV pacing group (50.7 vs. 12.3%, χ(2) = 25.1, P < 0.001) despite the similar DYS between the two groups at baseline (30 ± 13 vs. 26 ± 11 ms, P = 0.051). At a median follow-up of 4.8 years, patients developing early DYS had lower LVEF (53.2 ± 9.4 vs. 60.9 ± 8.0%, P < 0.001) and larger LV end-systolic volume (40.3 ± 23.7 vs. 29.3 ± 13.4 mL, P < 0.001) than those without DYS. Significant EF reduction (defined as ≥5%) occurred in 71.7% (33 in 46) of patients with DYS, but only in 30% (30 in 100) in those without DYS (χ(2) = 22.4, P < 0.001). Further analysis showed that both DYS at 1 month [odds ratio (OR): 3.113, P = 0.013] and RVA pacing (OR: 7.873, P < 0.001) independently predicted the deterioration of LV systolic function with pacing period of 4.8 years. Early pacing-induced DYS is a significant predictor of reduction of LV systolic function for long-term pacing, which could be prevented by BiV pacing at relatively long-period follow-up. Centre for Clinical Trials number, CUHK_CCT00037 (URL: http://www.cct.cuhk.edu.hk/Registry/publictrialrecord.aspx?trialid=CUHK_CCT00037).

Comparison of left ventricular systolic function and mechanical dyssynchrony using equilibrium radionuclide angiography in patients with right ventricular outflow tract versus right ventricular apical pacing: A prospective single-center study

BackgroundChronic ventricular pacing is known to adversely affect left ventricular (LV) function. Studies comparing right ventricular outflow tract (RVOT) pacing with RV apical (RVA) pacing have shown heterogeneous outcomes. Our aim was to objectively assess LV function and mechanical dyssynchrony in patients with RVOT and RVA pacing using equilibrium radionuclide angiography (ERNA). MethodsFifty-one patients who underwent permanent pacemaker implantation and had normal LV function were prospectively included. Twenty-nine patients had pacemaker lead implanted in the RVOT and 22 at the RVA site. All patients underwent ERNA within 5 days post-pacemaker implantation and follow-up studies at 6 and 12 months. Standard deviation of LV mean phase angle (SD LV mPA) expressed in degrees, which was derived by Fourier first harmonic analysis of phase images, was used to quantify left intraventricular dyssynchrony. ResultsNo significant difference was observed between the two groups with respect to indication (P = .894), Type/mode (P = .985), and percentage of ventricular pacing (P = .352). Paced QRS duration was significantly longer in RVA group than RVOT group (P = .05). There was no statistically significant difference between the RVA and RVOT groups at baseline with respect to LVEF (P = .596) and SD LV mPA (P = .327). Within the RVA group, a significant decline in LVEF was observed over 12-month follow-up (from 57.3% ± 5.32% to 55.6% ± 6.25%; P = .012). In the RVOT group, the change in LVEF was not statistically significant (from 56.7% ± 4.08% to 54.3% ± 6.63%; P = .159). No significant change in SD LV mPA was observed over 12-month follow-up within the RVA group (from 10.5 ± 2.58° to 10.4 ± 3.54°; P = 1.000) as well as in the RVOT group (from 9.7 ± 3.28° to 9.4 ± 2.85°; P = .769). However, between the RVA and RVOT groups, no significant difference was observed at 12-month follow-up in terms of LVEF and dyssynchrony (LVEF P = .488; SD LV mPA P = .296). ConclusionNo significant difference was observed between RVOT and RVA groups with regard to LV function and synchrony over a 12-month follow-up. RVOT pacing offers may lead to better preservation of LV function on longer follow-up.

Left Ventricular Mechanical Property Changes During Acute AV Synchronous Right Ventricular Pacing in Children.

Prolonged RV pacing is recognized as a cause of LV dysfunction due to dyssynchronous activation. There are no specific longitudinal parameters known to help predict RV pacing-induced LV dysfunction. The aim of the study was to assess the acute effects of AV synchronous RV pacing on LV mechanics using echocardiographic speckle tracking. Nineteen children, aged 6-23 years, underwent echocardiographic evaluation prior to and following elective electrophysiology and ablation studies. The subjects were evaluated in sinus rhythm and later with AV synchronous RV pacing at a cycle length of 550 ms with a short AV delay of 80 ms. The echocardiographic clips were analyzed using speckle tracking methods to calculate LV circumferential and longitudinal strain, rotation and twist in all conditions. Acute RV apical pacing decreased LV longitudinal strain from 16.1 ± 3.7% in sinus rhythm to 14.4 ± 3.3% (p = 0.03) and LV base rotation from -8.4° ± 3.6° to -6.4° ± 4.0° (p = 0.04). The circumferential strain, apical rotation and LV twist were not affected. Separate analysis of subjects with no prior preexcitation showed that acute RV pacing caused significant twist reduction, from 15.9° ± 7.6° to 12.1° ± 7.0° (p = 0.02), and decreased longitudinal strain and base rotation. Patients with preexcitation had abnormalities that persisted acutely after ablation. Acute RV apical pacing causes reductions in LV base rotation, longitudinal strain and twist. The recognition of abnormal LV activation patterns may provide longitudinal clues to LV dysfunction in chronically paced patients and potential novel indices of effective CRT interventions to reverse these abnormalities.

Heart Failure Summit Review: cardiac re-synchronisation therapy in the failing heart.

Extrapolating cardiac resynchronization therapy (CRT) to pediatric patients with heart failure has at times been difficult given the heterogeneity of pediatric cardiomyopathies, varying congenital heart disease (CHD) substrates, and the fact that most pediatric heart failure patients have right bundle branch block (RBBB) as opposed to LBBB. Yet, despite these limitations a number of multi-center retrospective studies in North America and Europe have identified some data to suggest that certain sub-populations tend to respond positively to CRT. In order to address some of the heterogeneity it is helpful to subdivide pediatric and young adult patients with CHD into four potential groups: (1) CRT for chronic RV pacing, (2) dilated cardiomyopathies, (3) pulmonary right ventricles, and (4) systemic right ventricles. The chronic RV paced group, especially long-standing RV apical pacing, with ventricular dyssynchrony has consistently shown to be the group that best responds to a proactive resynchronization course. CRT therapy in pulmonary right ventricles such as post-op tetralogy of Fallot have shown some promise and may be considered especially if there is evidence of concomitant left ventricular dysfunction with an electrical dyssynchrony. Patients with systemic right ventricles such as post-atrial baffle surgery or congenitally corrected transposition reportedly do well with CRT in the presence of both inter-ventricular and intra-ventricular dyssynchrony. There is little doubt that moving forward to best way to identify which pediatric patients with heart failure will respond to CRT, will require a collaborative effort between the electrophysiologist and the echocardiographer to identify appropriate candidates with electrical and mechanical dyssynchrony.

Paced QRS duration and myocardial scar amount: predictors of long-term outcome of right ventricular apical pacing.

Long-term right ventricular apical pacing (RVAP) is reportedly associated with heart failure (HF) development. However, the predictors of pacing-induced HF (PHF) remained unclear. We retrospectively enrolled 234 patients without structural heart disease who underwent a permanent pacemaker implantation with RVAP between 1982 and 2004. RVAP-induced HF was defined as left ventricular ejection fraction decrease >5% with HF symptom without other HF development etiology. The QRS duration of a paced beat (pQRSd) and myocardial scar score were analyzed from each patient's 12-lead ECG. During a mean 15.6years (range 3.3-30.0years), 48 patients (20.5%) patients developed RVAP-induced HF. The PHF group patients had a longer pQRSd (192.4±13.5 vs. 175.7±14.7ms in non-PHF patients, p<0.001) and a higher myocardial scar score (5.2±1.9 vs. 2.7±1.9, respectively p<0.001). In multivariate Cox regression analysis, old age at implantation [Hazard ratio (HR) 1.62, 95% confidential interval (CI) 1.22-2.16, p=0.001], a longer pQRSd (HR 1.54, 95% CI 1.15-2.05, p=0.003), a higher myocardial scar score (HR 1.23, 95% CI 1.03-1.49, p=0.037), and a higher percentage of ventricular pacing (HR 1.31, 95% CI 1.01-1.49, p=0.010) were independent predictors of PHF. Based on the results of the receiver-operating characteristic (ROC) curve, the pQRSd cutoff was 185ms (AUC 0.79, sensitivity 66.7%, specificity 76.3%) and myocardial scar score cutoff value was 4 (AUC 0.81, sensitivity 81.3%, specificity 66.1%). The pQRSd was positively correlated with scar score (r=0.70, p<0.001). pQRSd ≥185ms and/or myocardial scar score ≥4 might be independent long-term prognostic markers of PHF.

Comparative study on ultrasonic assessments of left ventricular systolic synchronicity under different cardiac pacing modes

Objective To compare left ventricular (LV) synchronization of direct His-bundle pacing(DHBP) and right ventricular apical pacing (RVAP) with two-dimensional speckle tracking imaging (2D-STI) and tissue Doppler imaging (TDI), and discuss the diagnostic value of 2D-STI and TDI in evaluation of left ventricular systolic synchronicity. Methods Twenty-four patients implanted with DHBP and RVAP were observed. Conventional echocardiography examination were undergone both at the mode of DHBP or RVAP respectively. The time to peak radial strain of LV 18 segments were derived from the parasternal short-axis views by 2D-STI, then calculated the standard deviations (SD) and the maximal temporal difference of LV 18 segments (Trs-SD and Trs-Dif), and the interval of time to peak radial strain between the anteroseptal wall and the posterior wall(Tas-post). The time to peak systolic velocity of LV 12 segments were derived from the apical axis views by TDI. The SD and the maximal temporal difference of 12 segments (Ts-SD and Ts-Dif) were calculated as the LV dyssynchrony index. Results All the systolic synchrony parameters derived from 2D-STI and TDI were more significantly shortened in DHBP than in RVAP (all P<0.01). For DHBP, the detection rate of LV synchronization was higher by 2D-STI than by TDI. For RVAP the detection rate of LV dyssynchronization was also higher by 2D-STI than by TDI with RVAP lead (all P<0.05). Conclusions DHBP is more beneficial than RVAP in LV syschronization and LV function, RVAP may induce left ventricular systolic asynchrony. Both 2D-STI and TDI can assess the LV synchronization quantitatively, but 2D-STI may be more superior on the detection rate than TDI. Key words: Echocardiography; Cardiac pacing, artificial; Ventricular function, left

Routine use of biventricular pacing is not warranted for patients with heart block.

Ventricular pacing can be lifesaving for patients with complete atrioventricular block (AVB). Since the introduction of permanent transvenous cardiac pacing >40 years ago, the right ventricular (RV) apex has been the preferred site for ventricular stimulation. This location provides good fixation and low capture thresholds. However, RV apical pacing may induce cardiac dyssynchrony. Hence, it has been suggested that all patients with symptomatic AVB (regardless of current indication for biventricular pacing), with anticipated high RV pacing burden, should receive preventive biventricular pacing. In this article, we review the physiological effects of RV pacing, data from observational studies (Table I in the Data Supplement),1–6 and available randomized trials comparing biventricular versus RV pacing (Table).7–16 View this table: Table. Randomized Controlled Studies Comparing Right Ventricular and Biventricular Pacing Response by Fang et al on p 738 Since the initial report of the use of endocardial pacing to treat complete AVB by Furman and Schwedel in 195917, pacemakers have evolved dramatically into complex devices with the ability to sequentially pace the atrium and both ventricles. Between 1993 and 2009, 2.9 million patients received a permanent pacemaker in the United States.18 During this time, overall pacemaker use increased by 55.6%. However, although the use of dual chamber (DDD) pacemakers increased by at least 40%, the use of single-chamber ventricular (VVI) pacemakers decreased ≈50%,18 despite the evidence from large pacing trials19–21 indicating no major differences in outcomes between single and dual chamber pacing modes. In fact, by 2009, DDD pacemakers accounted for 82% of all implants (VVI for only 14%).18 These statistics speak loudly about the impact of technology on daily clinical practice. A similar quandary now exists with regards to biventricular pacing. We suggest that the global utilization of biventricular pacing for all …