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Biventricular Pacing in Children After Surgery for Congenital Heart Disease

2016-06-20 18:53:21 | BioPortfolio

Summary

Surgery with cardiopulmonary bypass (CPB) for congenital heart disease (CHD) causes low cardiac index (CI). With the increasing success of surgery for CHD, mortality has decreased and emphasis has shifted to post-operative morbidity and recovery. Children with CHD undergoing surgery with CPB can experience well-characterized post-operative cardiac dysfunction. When severe, patients can develop clinically important low cardiac output syndrome (LCOS) and hemodynamic instability. Management of LCOS and hemodynamic compromise is primarily accomplished via intravenous durgs like milrinone, dopamine or dobutamine, which affect the strength of the heart's muscular contractions. These are used to maintain adequate blood pressure (BP) and CI. However, inotropic agents are potentially detrimental to myocardial function and may increase risk for post-operative arrhythmia and impair post-operative recovery by increasing oxygen demand and myocardial oxygen consumption (VO2). In combination with the increased VO2 associated with CPB-induced systemic inflammatory response patients can develop a critical mismatch between oxygen supply and demand, essentially the definition of LCOS. Therefore, therapies that improve CI and hemodynamic stability without increased VO2 are beneficial. This study will test whether BiVp, a specialized yet simple pacing technique, can improve post-operative CI and recovery in infants with electro-mechanical dyssynchrony (EMD) after CHD surgery. This study hypothesizes that Continuous BiVp increases the mean change in CI from baseline to 72 hours in infants with EMD following CHD surgery compared to standard care alone.

Description

In adults with heart failure with intrinsic or iatrogenic left bundle branch block (eg, RV pacing), and more recently in those with narrow QRS complex, pacing the heart with advanced pacing techniques from both the left and right ventricle (LV, RV) termed cardiac resynchronization therapy (CRT) improves resting systolic heart function and mechanoenergetics.1 In these patients, CRT has been shown to increase LV stroke volume, ejection fraction, and stroke work, resulting in an enhancement of LV myocardial efficiency, without an increase in oxidative metabolism and even a decrease in energy utilization.2-4 Furthermore, oxygen consumption seems to be distributed more homogeneously during CRT.2 Beyond increasing resting myocardial efficiency, CRT may increase metabolic reserve as judged by the increase in cardiac work in response to dobutamine.5 CRT has also been shown to restore homogeneous myocardial glucose metabolism, without a decrease in myocardial perfusion.6 These findings were mirrored by similar findings regarding the effects of CRT on myocardial perfusion. Resting myocardial blood perfusion was unaltered by CRT despite an increase in left ventricular function. However, the distribution pattern of resting myocardial blood perfusion became more homogeneous, while hyperemic myocardial blood perfusion and myocardial blood perfusion reserve were enhanced by CRT.7 In the long-term, CRT improves morbidity and mortality in adults with heart failure.8, 9

Children have myocardial dysfunction and possibly mechanical dyssynchrony following cardiopulmonary bypass and cardiac surgery. A significant number of children with congenital heart disease have either interventricular conduction delay or right bundle branch block (RBBB). For example, RBBB may occur in patients after ventricular septal defect repair. Others children may develop iatrogenic bundle branch block while requiring ventricular pacing for rate control, hemodynamic improvement or atrioventricular block. When postoperative pacing is indicated, the current method used is to sense or pace the right atrium, depending on the indication, and to pace the right ventricle (univentricular pacing). However, conventional RV univentricular pacing may increase myocardial stress and oxygen utilization through inhomogeneous contraction,10 while long-term right ventricular (univentricular) pacing has been shown in some patients to have detrimental effects on left ventricular remodeling, left ventricular function and clinical outcomes.11-13 Beyond the potential for pacing related myocardial stress and oxygen consumption, the post-operative care of children with congenital heart disease necessitates the use of potent inotropic agents at the expense of increased myocardial oxygen consumption, unwanted effects in the vulnerable post-bypass myocardium.14-16 Preliminary data in children with congenital heart disease undergoing surgical repair have shown acute benefits of CRT as manifested by increased systolic blood pressure and improved cardiac output associated with a reduced QRS duration. These beneficial effects were obtained in children with both single and dual ventricular physiology.17-20 Pham et al showed improvement in cardiac index with biventricular pacing in children after heart surgery, but not with conventional atrioventricular pacing, suggesting that in patients needing pacing in the postoperative period, biventricular pacing is better than conventional pacing, a conclusion previously reached in adults in the setting of cardiomyopathy.21-23 Despite these beneficial immediate hemodynamic effects, and despite preliminary data on the beneficial effects of CRT in children with congenital heart disease,24-26 it is not known whether a longer period of biventricular pacing in the post-operative period following surgery for congenital heart disease is beneficial and whether this intervention can lead to improved clinical outcomes such as reduction of the use of inotropes, time to extubation and length of admission to the critical care unit. To answer these questions, a prospective, randomized trial is needed. The current study would serve as a pilot study for a larger trial in the event of encouraging results.

Hypothesis

Biventricular pacing improves recovery after cardiac surgery with cardiopulmonary bypass in children with congenital heart disease.

Objectives

Study the effects of biventricular pacing on post-operative hemodynamics and clinical outcomes in children after surgery for congenital heart disease.

Design

Randomized, non-blinded, clinical intervention.

Study Design

Allocation: Randomized, Endpoint Classification: Safety/Efficacy Study, Intervention Model: Parallel Assignment, Masking: Single Blind (Investigator), Primary Purpose: Treatment

Conditions

Congenital Heart Disease (CHD)

Intervention

Biventricular pacing

Location

Hospital for Sick Children
Toronto
Ontario
Canada
M5G1X8

Status

Completed

Source

The Hospital for Sick Children

Results (where available)

View Results

Links

Published on BioPortfolio: 2016-06-20T18:53:21-0400

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PubMed Articles [18994 Associated PubMed Articles listed on BioPortfolio]

Atlas-Based Computational Analysis of Heart Shape and Function in Congenital Heart Disease.

Approximately 1% of all babies are born with some form of congenital heart defect. Many serious forms of CHD can now be surgically corrected after birth, which has led to improved survival into adulth...

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Initial in vitro testing of a paediatric continuous-flow total artificial heart.

Mechanical circulatory support has become standard therapy for adult patients with end-stage heart failure; however, in paediatric patients with congenital heart disease, the options for chronic mecha...

Long-term Reverse Remodeling by Cardiac Resynchronization Therapy with MultiPoint Pacing: A Feasibility Study of Noninvasive Hemodynamics Guided Device Programming.

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Medical and Biotech [MESH] Definitions

The restoration of the sequential order of contraction and relaxation of the HEART ATRIA and HEART VENTRICLES by atrio-biventricular pacing.

Regulation of the rate of contraction of the heart muscles by an artificial pacemaker.

Cardiac manifestation of systemic rheumatological conditions, such as RHEUMATIC FEVER. Rheumatic heart disease can involve any part the heart, most often the HEART VALVES and the ENDOCARDIUM.

Occlusion of the outflow tract in either the LEFT VENTRICLE or the RIGHT VENTRICLE of the heart. This may result from CONGENITAL HEART DEFECTS, predisposing heart diseases, complications of surgery, or HEART NEOPLASMS.

Moving oneself through space while confused or otherwise cognitively impaired. Patterns include akathisia, exhibiting neuroleptic-induced pacing and restlessness; exit seekers who are often newly admitted institution residents who try to open locked exit doors; self-stimulators who perform other activities such as turning doorknobs, in addition to continuous pacing; and modelers who shadow other pacers.

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