Article

Left ventricular septal and left ventricular apical pacing chronically maintain cardiac contractile coordination, pump function and efficiency.

Department of Physiology, Cardiovascular Research Institute Maastricht, Maastricht University, 6200 MD Maastricht, The Netherlands.
Circulation Arrhythmia and Electrophysiology (Impact Factor: 5.95). 10/2009; 2(5):571-9. DOI: 10.1161/CIRCEP.109.882910
Source: PubMed

ABSTRACT Conventional right ventricular (RV) apex pacing can lead to adverse clinical outcome associated with asynchronous activation and reduced left ventricular (LV) pump function. We investigated to what extent alternate RV (septum) and LV (septum, apex) pacing sites improve LV electric activation, mechanics, hemodynamic performance, and efficiency over 4 months of pacing.
After AV nodal ablation, mongrel dogs were randomized to receive 16 weeks of VDD pacing at the RV apex, RV septum, LV apex, or LV septum (transventricular septal approach). Electric activation maps (combined epicardial contact and endocardial noncontact) showed that RV apical and RV septal pacing induced significantly greater electric desynchronization than LV apical and LV septal pacing. RV apex and RV septal pacing also significantly increased mechanical dyssynchrony, discoordination (MRI tagging) and blood flow redistribution (microspheres) and reduced LV contractility, relaxation, and myocardial efficiency (stroke work/myocardial oxygen consumption). In contrast, LV apical and LV septal pacing did not significantly alter these parameters as compared with the values during intrinsic conduction. At 16 weeks, acute intrasubject comparison showed that single-site LV apical and LV septal pacing generally resulted in similar or better contractility, relaxation, and efficiency as compared with acute biventricular pacing.
Acute and chronic LV apical and LV septal pacing maintain regional cardiac mechanics, contractility, relaxation, and efficiency near native levels, whereas RV apical or RV septal pacing diminish these variables. Acute LV apical and LV septal pacing tend to maintain or improve contractility and efficiency compared with biventricular pacing.

0 Bookmarks
 · 
61 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The mechanoenergetic effects of atrioventricular delay optimization during biventricular pacing ("cardiac resynchronization therapy", CRT) are unknown. Eleven patients with heart failure and left bundle branch block (LBBB) underwent invasive measurements of left ventricular (LV) developed pressure, aortic flow velocity-time-integral (VTI) and myocardial oxygen consumption (MVO2) at 4 pacing states: biventricular pacing (with VV 0ms) at AVD 40ms (AV-40), AVD 120ms (AV-120, a common nominal AV delay), at their pre-identified individualised haemodynamic optimum (AV-Opt); and intrinsic conduction (LBBB). AV-120, relative to LBBB, increased LV developed pressure by a mean of 11(SEM 2)%, p=0.001, and aortic VTI by 11(SEM 3)%, p=0.002, but also increased MVO2 by 11(SEM 5)%, p=0.04. AV-Opt further increased LV developed pressure by a mean of 2(SEM 1)%, p=0.035 and aortic VTI by 4(SEM 1)%, p=0.017. MVO2 trended further up by 7(SEM 5)%, p=0.22. Mechanoenergetics at AV-40 were no different from LBBB. The 4 states lay on a straight line for Δexternal work (ΔLV developed pressure×Δaortic VTI) against ΔMVO2, with slope 1.80, significantly >1 (p=0.02). Biventricular pacing and atrioventricular delay optimization increased external cardiac work done but also myocardial oxygen consumption. Nevertheless, the increase in cardiac work was ~80% greater than the increase in oxygen consumption, signifying an improvement in cardiac mechanoenergetics. Finally, the incremental effect of optimization on external work was approximately one-third beyond that of nominal AV pacing, along the same favourable efficiency trajectory, suggesting that AV delay dominates the biventricular pacing effect - which may therefore not be mainly "resynchronization".
    International journal of cardiology 10/2013; · 6.18 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Cardiac resynchronization therapy (CRT) emerged 2 decades ago as a useful form of device therapy for heart failure associated with abnormal ventricular conduction, indicated by a wide QRS complex. In this Review, we present insights into how to achieve the greatest benefits with this pacemaker therapy. Outcomes from CRT can be improved by appropriate patient selection, careful positioning of right and left ventricular pacing electrodes, and optimal timing of electrode stimulation. Left bundle branch block (LBBB), which can be detected on an electrocardiogram, is the predominant substrate for CRT, and patients with this conduction abnormality yield the most benefit. However, other features, such as QRS morphology, mechanical dyssynchrony, myocardial scarring, and the aetiology of heart failure, might also determine the benefit of CRT. No single left ventricular pacing site suits all patients, but a late-activated site, during either the intrinsic LBBB rhythm or right ventricular pacing, should be selected. Positioning the lead inside a scarred region substantially impairs outcomes. Optimization of stimulation intervals improves cardiac pump function in the short term, but CRT procedures must become easier and more reliable, perhaps with the use of electrocardiographic measures, to improve long-term outcomes.
    Nature Reviews Cardiology 05/2014; · 10.40 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: To review and prioritize data on pediatric cardiac pacing published during the period of the last 18 months. New approaches to preservation of ventricular function in pediatric pacing are based on recent publications confirming major influence of the ventricular pacing site on left ventricular (LV) function and synchrony. Current studies on epicardial vs. transvenous pacing continue to show survival superiority of endocardial leads. Long-term outcome of epicardial pacing may, however, be positively influenced by technical refinements. Recent amendments of the guidelines for cardiac resynchronization therapy (CRT) in adult idiopathic and ischemic cardiomyopathy are likely to influence CRT indications in children. Novel data give interesting insights into implantable cardioverter-defibrillator (ICD) lead survival as well as the use of ICDs in young patients with hypertrophic cardiomyopathy. Pediatric cardiac pacing and ICD therapy is still a developing field likely to improve with technical refinements, proper lead placement and more specific therapy indications. The current review will give the reader information about recent developments and directions for the future.
    Current opinion in cardiology 11/2013; · 2.66 Impact Factor

Full-text (2 Sources)

View
23 Downloads
Available from
May 16, 2014