Clinical Trial: Exercise in Chronically Paced Children

Study Status: Completed
Recruit Status: Completed
Study Type: Observational

Official Title: A Single Center, Prospective, Pilot Study Examining the Evaluation of Exercise Capacity in Chronically RV Paced Children and Young Adults

Brief Summary: The purpose of this study is to evaluate the exercise capacity of patients with complete heart block who are chronically being paced from the right ventricle. Also, we hope to correlate the level of uncoordinated contraction with the patients exercise capacity. We will enroll patients with complete heart block as diagnosed by standard electrocardiographic means and now have a permanent pacemaker. All patients we approach for this study will receive an echocardiogram to assess their heart function. As part of the echocardiogram, they will also receive a Tissue Synchronization Imaging (TSI) evaluation to assess the level of uncoordinated contraction they have. The patients will then be subjected to a cardiac exercise stress test which will involve them running on a treadmill until they cannot continue while data is collected regarding their heart's response to exercise. All portions of the study are noninvasive, which means they work from probes and monitors outside the body.

Detailed Summary:

In third degree, or complete atrioventricular (AV) block, atrial electrical impulses fail to conduct to the ventricles. Congenital complete AV block (CCAVB) has an incidence of 1 in 15,000 to 1 in 25,000 live births and has a strong association with maternal antibodies. Patients with isolated CCAVB range from completely asymptomatic to experiencing syncope, exercise intolerance or congestive heart failure. A portion of the symptoms attributable to CCAVB are secondary to the inability to increase heart rate, and hence cardiac output, in response to varying physiologic demands. For symptomatic patients, the mainstay of therapy has been cardiac pacing. Dual chamber pacing, with atrial sensing and ventricular pacing, allows for restoration of physiologic heart rates and response to exercise or increased metabolic demands. Resumption of AV synchrony allows for more efficient ventricular filling. Overall, pacing in patients with CCAVB would be expected to result in improved cardiac function and exercise tolerance.

The traditional ventricular site for pacing in patients with CCAVB has been the right ventricular apex (RVA). This results in interventricular dyssynchrony as pacing first stimulates the right ventricle, rather than the typical midline ventricular activation pattern seen in patients with intact AV node conduction. Mounting evidence shows that long term RV pacing results in morphologic changes to the LV with resultant compromised performance. Further studies have shown that chronic RV pacing diminishes exercise capacity in patients with heart failure as well as asymptomatic adults. There have been studies, by our group in particular, that have documented ventricular changes in the paced pediatric patient. No published study has examined the possible deleterious effects of RV pacing on exercise capacity in children. We, therefore, propose to do a detailed evaluation of
Sponsor: Emory University

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Information By: Emory University

Dates:
Date Received: September 8, 2006
Date Started: January 2007
Date Completion:
Last Updated: May 30, 2012
Last Verified: May 2012