Single-site Left Ventricular Pacing Research Articles

Left Ventricular Enlargement, Cardiac Resynchronization Therapy Efficacy, and Impact of MultiPoint Pacing.

Left ventricular (LV) epicardial pacing results in slowly propagating paced wavefronts. We postulated that this effect might limit cardiac resynchronization therapy efficacy in patients with LV enlargement using conventional biventricular pacing with single-site LV pacing, but be mitigated by LV stimulation from 2 widely spaced sites using MultiPoint pacing with wide anatomic separation (MPP-AS: ≥30 mm). We tested this hypothesis in the multicenter randomized MPP investigational device exemption trial. Following implant, quadripolar biventricular single-site pacing was activated in all patients (n=506). From 3 to 9 months postimplant, among patients with available baseline LV end-diastolic volume (LVEDV) measures, 188 received biventricular single-site pacing and 43 received MPP-AS. Patients were dichotomized by median baseline LVEDV indexed to height (LVEDVIMedian). Outcomes were measured by the clinical composite score (primary efficacy end point), quality of life, LV structural remodeling (↑EF >5% and ↓ESV 10%) and heart failure event/cardiovascular death. LVEDVIMedian was 1.1 mL/cm. Baseline characteristics differed in patients with LVEDVI>Median versus LVEDVI≤Median. Among patients with LVEDVI>Median, biventricular single-site pacing was less efficacious compared to patients with LVEDVI≤Median (clinical composite score, 65% versus 79%). In contrast, MPP-AS programming generated greater clinical composite score response (92% versus 65%, P=0.023) and improved quality of life (-31.0±29.7 versus -15.7±22.1, P=0.038) versus biventricular single-site pacing in patients with LVEDVI>Median. Reverse remodeling trended better with MPP-AS programming. In patients with LVEDVI>Median, heart failure event rate increased following the 3-month randomization point with biventricular single-site pacing (0.0150±0.1725 in LVEDVI>Median versus -0.0190±0.0808 in LVEDVI ≤Median, P=0.012), but no heart failure event occurred in patients with MPP-AS programming between 3 and 9 months in LVEDVI>Median. All measured outcomes did not differ in patients receiving MPP-AS and biventricular single-site pacing with LVEDVI≤Median. Conventional biventricular single-site pacing, even with a quadripolar lead, has reduced efficacy in patients with LV enlargement. However, the greatest response rate in patients with larger hearts was observed when programmed to MPP-AS pacing.

Bipolar active fixation left ventricular lead or quadripolar passive fixation lead? An Italian multicenter experience.

About one-third of patients receiving cardiac resynchronization therapy (CRT) are not responders, due to either patient selection or technical issues. Left ventricular quadripolar passive fixation leads (QPL) and bipolar active fixation (BAF) leads have been designed to ensure a targeted left ventricular stimulation area, minimizing lead dislodgments and phrenic nerve stimulation (PNS). The aim was to compare real-world safety and efficacy of BAF (Attain Stability, Medtronic Plc.) and QPL (Attain Performa, Medtronic Plc.). We performed a retrospective analysis examining procedural and follow-up data of 261 BAF and 124 QPL (programmed to single-site left ventricular pacing), included in the ClinicalService project from 16 Italian hospitals. At median follow-up of 12 months, no difference in left ventricular pacing threshold was recorded between BAF and QPL (1.3 ± 0.9 V @0.4 ms vs. 1.3 ± 1.0 V @0.4 ms; P = 0.749). Total left ventricular lead dislodgement rate was 1.43/100 patient-years in BAF vs. 2.9/100 patient-years in QPL (P = 0.583). However, no dislodgements occurred among BAF after hospital discharge. Events requiring repeated surgery or permanently turning CRT off occurred in 0.8% of BAF, as compared with 4.0% of QPL (P = 0.025). There was no difference between groups in the echo CRT responders' rate (70% of BAF and 66% of QPL; P = 0.589) or in the annual rate of heart failure hospitalization (P = 0.513). BAF resulted in noninferior clinical outcome and CRT responders' rate in comparison to QPL. Moreover, BAF ensured more precise and stable placement in cardiac veins, with comparable electrical performance and less than 1% patients with unsolved PNS.

Haemodynamic effects of cardiac resynchronization therapy using single-vein, three-pole, multipoint left ventricular pacing in patients with ischaemic cardiomyopathy and a left ventricular free wall scar: the MAESTRO study.

The clinical response to cardiac resynchronization therapy (CRT) is variable. Multipoint left ventricular (LV) pacing could achieve more effective haemodynamic response than single-point LV pacing. Deployment of an LV lead over myocardial scar is associated with a poor haemodynamic response to and clinical outcome of CRT. We sought to determine whether the acute haemodynamic response to CRT using three-pole LV multipoint pacing (CRT3P-MPP) is superior to that to conventional CRT using single-site LV pacing (CRTSP) in patients with ischaemic cardiomyopathy and an LV free wall scar. Sixteen patients with ischaemic cardiomyopathy [aged 72.6 ± 7.7 years (mean ± SD), 81.3% male, QRS: 146.0 ± 14.2 ms, LBBB in 14 (87.5%)] in whom the LV lead was intentionally deployed straddling an LV free wall scar (assessed using cardiac magnetic resonance), underwent assessment of LV + dP/dtmax during CRT3P-MPP and CRTSP. Interindividually, the ΔLV + dP/dtmax in relation to AAI pacing with CRT3P-MPP (6.2 ± 13.3%) was higher than with basal and mid CRTSP (both P < 0.001), but similar to apical CRTSP. Intraindividually, significant differences in the ΔLV + dP/dtmax to optimal and worst pacing configurations were observed in 10 (62.5%) patients. Of the 8 patients who responded to at least one configuration, CRT3P-MPP was optimal in 5 (62.5%) and apical CRTSP was optimal in 3 (37.5%) (P = 0.0047). In terms of acute haemodynamic response, CRT3P-MPP was comparable an apical CRTSP and superior to basal and distal CRTSP. In the absence of within-device haemodynamic optimization, CRT3P-MPP may offer a haemodynamic advantage over a fixed CRTSP configuration.

Acute hemodynamic effects of single- and dual-site left ventricular pacing employing a dual cathodal coronary sinus lead.

We studied the acute hemodynamic effect of left ventricular (LV) pacing from a dual cathodal coronary sinus (CS) lead in a both single- and dual-site electrode configuration. In 17 patients who underwent implantation of a cardiac resynchronization therapy-defibrillator system with dual cathodal CS leads, LV stimulation was performed from the distal and proximal electrode separately and from both electrodes simultaneously. The acute hemodynamic response was evaluated by invasive measurement of LVdP/dtmax. Timing of LV electrical activation time measured from onset QRS to LV sense during intrinsic rhythm at both electrodes were determined from simultaneous intracardiac recordings. The latter results were compared to those of an additional group of 26 patients in whom no hemodynamic effects were evaluated. Baseline LVdP/dtmax was 897 ± 222 mm Hg/s. Single-site LV pacing resulted in a rise of LVdP/dtmax to 1,053 ± 266 mm Hg/s (+17.4%) taking the best of the two sites and 1,020 ± 254 mm Hg (+13.7%) at the worst site (P = 0.0001). In the dual-site pacing configuration LVdP/dtmax was 1,026 ± 243 mm Hg/s (+14.1%). P value for single best versus dual site was 0.005, and for dual site versus worst single site was 0.18 (n.s.). Even with a relatively small distance of 20-21 mm between stimulation electrodes, there is a significant difference in acute hemodynamic effect from the single best and worst site. Dual-site LV pacing offers no hemodynamic benefit over the best single pacing site. The short electrode distance may have been a limitation and results may not be applicable to other forms of multisite pacing.

Biophysical modeling to simulate the response to multisite left ventricular stimulation using a quadripolar pacing lead.

Response to cardiac resynchronization therapy (CRT) is reduced in patients with posterolateral scar. Multipolar pacing leads offer the ability to select desirable pacing sites and/or stimulate from multiple pacing sites concurrently using a single lead position. Despite this potential, the clinical evaluation and identification of metrics for optimization of multisite CRT (MCRT) has not been performed. The efficacy of MCRT via a quadripolar lead with two left ventricular (LV) pacing sites in conjunction with right ventricular pacing was compared with single-site LV pacing using a coupled electromechanical biophysical model of the human heart with no, mild, or severe scar in the LV posterolateral wall. The maximum dP/dt(max) improvement from baseline was 21%, 23%, and 21% for standard CRT versus 22%, 24%, and 25% for MCRT for no, mild, and severe scar, respectively. In the presence of severe scar, there was an incremental benefit of multisite versus standard CRT (25% vs 21%, 19% relative improvement in response). Minimizing total activation time (analogous to QRS duration) or minimizing the activation time of short-axis slices of the heart did not correlate with CRT response. The peak electrical activation wave area in the LV corresponded with CRT response with an R(2) value between 0.42 and 0.75. Biophysical modeling predicts that in the presence of posterolateral scar MCRT offers an improved response over conventional CRT. Maximizing the activation wave area in the LV had the most consistent correlation with CRT response, independent of pacing protocol, scar size, or lead location.

Single Site Left Ventricular Pacing induced Dyssynchrony and Cardiomyopathy

Single site left ventricular (LV) pacing in the absence of intrinsic ventricular activity can be as detrimental to LV function as right ventricular apical pacing. This report describes a patient with complete heart block who developed significant dyssynchrony and cardiomyopathy secondary to single site lateral LV pacing. The process was reversed by placement of a second anterior LV lead.

Cardiac resynchronization therapy: back to ECG?

In recent years, considerable effort has been devoted to improving patient selection and the programming of cardiac resynchronization therapy (CRT). Mechanical dyssynchrony has been investigated through echocardiography and the reliability of ECG in selecting patients has been criticized and doubt has been cast on its role. Up to now, patient selection for CRT has relied upon the criteria of a prolonged QRS, evidence of the electrical impairment of the conduction system. Can we get more information from ECG morphology? Can it provide any marker for selecting candidates to CRT? Can we obtain useful information from the paced ECG morphology by analysis of fusion beats? Can we use ECG to optimize biventricular or single-site left ventricular pacing programming? The present review provides a critical analysis of the criteria for patient selection and the methods for optimal device setting, all based on 12-lead ECG morphology.

Left Ventricular Endocardial Pacing Improves Resynchronization Therapy in Canine Left Bundle-Branch Hearts

Background— We investigated the benefits of the more physiological activation achieved by left ventricular (LV) endocardial pacing (ENDO) as compared with conventional epicardial (EPI) LV pacing in cardiac resynchronization therapy. Methods and Results— In 8 anesthetized dogs with experimental left bundle-branch block, pacing leads were positioned in the right atrium, right ventricle, and at 8 paired (EPI and ENDO) LV sites. Systolic LV pump function was assessed as LVdP/dtmax and stroke work and diastolic function as LVdP/dtmin. Electrical activation and dispersion of repolarization were determined from 122 epicardial and endocardial electrodes and from analysis of the surface ECG. Overall, ENDO-biventricular (BiV) pacing more than doubled the degree of electrical resynchronization and increased the benefit on LVdP/dtmax and stroke work by 90% and 50%, respectively, as compared with EPI-BiV pacing. During single-site LV pacing, the range of AV intervals with a &gt;10% increase in LV resynchronization (79�31 versus 32�24 ms, P &lt;0.05) and LVdP/dtmax (92�29 versus 63�39 ms) was significantly longer for ENDO than for EPI pacing. EPI-BiV but not ENDO-BiV pacing created a significant (40�21 ms) transmural dispersion of repolarization. Conclusions— Data from this acute animal study indicate that the use of an endocardial LV pacing electrode may increase the efficacy of resynchronization therapy as compared with conventional epicardial resynchronization therapy.

Cardiac Resynchronization in a Child with Dilated Cardiomyopathy and Borderline QRS Duration: Speckle Tracking Guided Lead Placement

Cardiac resynchronization therapy (CRT) is proved to prevent heart transplantation in some patients with dilated cardiomyopathy and mechanical dyssynchrony. We report of the benefit of CRT accomplished by atrial synchronized single-site left ventricular pacing in an 8-year-old boy with idiopathic dilated cardiomyopathy, normal atrioventricular conduction, borderline QRS complex duration (120 ms), and marked mechanical left ventricular dyssynchrony proved by echocardiographic speckle tracking.

Abstract 2163: Single-site Left Ventricular Apex And Left Ventricular Septal Pacing For Long Term Maintenance Of Cardiac Contractility

Objective: Conventional right ventricular (RV) apex pacing is associated with asynchronous activation and reduced left ventricular (LV) pump function. Previous studies have shown acute hemodynamic benefits over RV apex pacing by LV septal or LV apex pacing. We investigated whether this improvement translates into a long-term benefit and how acute LV function during single site LV pacing compares to biventricular pacing. Methods: After AV-nodal ablation, mongrel dogs were randomized to receive 16 weeks of VDD pacing at the RV apex (n = 7), LV apex (n = 7), or LV mid-septum (n = 8; trans-ventricular septal approach). LV contractility (dP/dt max /P instantaneous ) was measured during normal ventricular conduction from atrial pacing (AP) and during ventricular pacing 1–3 hours and 16 weeks after implant. At 16 weeks, contractility was also measured after an acute switch from the implant site (IS) to the non-implanted apex (both for LV septal group) and to RV apex + LV lateral (BiV) pacing. Results: While acute and chronic RV apex pacing significantly reduced contractility (Figure a ; mean ± SD, *p&lt;0.05 contrasted to 1), LV pacing maintained contractility near AP levels. After 16 weeks of RV apex pacing, switching to LV apex pacing (but not BiV pacing) increased contractility (Figure b ). After 16 weeks of LV pacing, switching to RV apex pacing decreased contractility. Collectively, acute LV apex pacing enhanced contractility over acute BiV (p&lt;.001). Conclusions: Chronic LV apex and LV mid-septal pacing maintain contractility near normal levels, and at a higher level than RV apex pacing. Acutely, LV apex pacing improves contractility compared to BiV pacing.

Successful cardiac resynchronization with single-site left ventricular pacing in children

Background Dyssynchronous left ventricular (LV) contraction due to permanent right ventricular apex (RVA) pacing or delayed electrical activation as typically observed in left bundle brunch block (LBBB) has a negative impact on LV function. Objective was to evaluate the impact of epicardial single-site LV pacing in children on LV function and resynchronization. Patients Single-site epicardial LV free wall pacing was established in 6 children with congenital heart disease and echocardiographic signs of LV dyssynchrony. Reasons for dyssynchrony were either long-term RVA pacing ( n = 5; pacing duration: 7.7 ± 2.4 years) or LBBB with drug-resistant congestive heart failure ( n = 1). Results After 1 month of single-site LV pacing, LV ejection fraction increased (41 ± 6 versus 53 ± 8%) and LV enddiastolic volume decreased (70 ± 22 versus 63 ± 18 ml/m 2) as compared to pre-implant measurements. Interventricular mechanical delay decreased (67 ± 15 versus 16 ± 15 ms) and intraventricular synchrony was restored (septal-to-posterior wall motion delay: 312 ± 24 versus 95 ± 57 ms). Accordingly, circumferential 2D strain demonstrated a decrease of LV mechanical delay (201 ± 35 versus 99 ± 23 ms). Conclusion After 1 month of single-site LV pacing, conventional and 2D strain derived echocardiographic measurements indicated improved ventricular function and synchronization in children with previous RVA pacing or LBBB. Further studies are needed to evaluate whether single-site LV pacing may be sufficient for resynchronization therapy.

The method of ECG fusion band for the best setting in patients with heart failure treated with single-site left ventricular pacing

The method of ECG fusion band for the best setting in patients with heart failure treated with single-site left ventricular pacing

Effect of single-site Left Ventricular Pacing on mitral regurgitation and interventricular delay in patients with HF: may ECG morphology guide the optimal setting?

Effect of single-site Left Ventricular Pacing on mitral regurgitation and interventricular delay in patients with HF: may ECG morphology guide the optimal setting?

What factors influence hemodynamic improvement after right ventricular to biventricular pacing system upgrade?

It is still hard to predict hemodynamic effects after biventricular pacing system (BiVp) implantation despite established inclusion criteria for CRT and left ventricular pacing (LVp) techniques. The aim of the study was to find the predictors of acute hemodynamic improvement after right ventricular (RVp) to biventricular pacing system upgrade. Methods: The study group consisted of 69 patients with permanently implanted BiV pacing system with standard CRT criteria. Hemodynamic effect was determined using impedance cardiography (BioZ.com; Cardiodynamics). Cardiac Index (CI) and other indirect parameters were determined during 3 min periods of RV and BiV pacing in turn. Correlations were searched among clinical, echocardiographic, ECG and initial hemodynamic parameters and multivariate analysis was performed as well. Results: Cardiac contractility was higher during BiVp than RVp and LVp: CI (l/min/m2): RVp 2,29* LVp 2,20∧ BiVp 2,56*∧ [*∧ANOVA-LSD p>0,05]. Increase of CI after RV to BiV reprogramming correlated with CI during RVp (r=−0,50 p>0,001), Thoracic Fluid Index (TFI) (r=−0,32 p>0,01) and with difference of CI between RVp vs LVp (r=0,57 p>0,001) and LVp vs BiVp (r= 0,30 p>0,05). Values of CI during LVp, BiVp, echocardiographic parameters, NYHA class, RVp-, LVp-, BiVp- QRS durations and axis, and their changes did not correlated with differences of CI during RVp and BiVp. Multivariate analysis showed that only CI during RVp and RVp vs LVp CI difference determined acute hemodynamic effect of BiVp in comparison to RVp. Conclusions: Increase of CI after RVp to BiVp upgrade depends mainly on cardiac performance during right ventricular pacing and its improvement caused by change from RVp to single site LVp.