CRM and Fusion Beats: Effects of Progressive Fusion on Intra-left Ventricular Mechanical Function

Study Overview
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Brief Summary
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This study is looking at cardiac rhythm management (CRM) and fusion beats in patients who have a pacemaker or implantable cardioverter-defibrillator (ICD), to determine if there is a correlation between the time between the contraction of the upper chambers of the heart (atrium) and the lower chambers of the heart, (ventricle) and heart function. Some studies of people with pacemakers have been done to determine if shortening the time of contraction between the atrium and ventricle could benefit the function of the left ventricle. These studies have shown that there is no benefit in heart function.There have been other studies which have shown that chronic pacing of the right ventricle, especially with the lead placed at the tip of the right ventricle, can lead to a decrease in the function of the left ventricle and congestive heart failure. In some patients long term pacing of the right ventricle has also been associated with a reduction in the ability of the left ventricle to pump blood. This is know as a reduced left ventricular ejection fraction, which can be documented by an echocardiogram. This study proposes to evaluate the acute effects of progressive paced fusion beats on the left ventricle to answer the question whether there is an delay between the atrium and ventricle that is too long or too short.

Official Title
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CRM and Fusion Beats: Effects of Progressive Fusion on Intra-left Ventricular Mechanical Function

Conditions
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Cardiomyopathy

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Dual chamber pacemaker or ICD device Left Ventrical Ejection Fraction (LVEF) 40% or less Sinus Rhythm with intact atrioventricular conduction with a PR interval greater than 200 msec QRS less than 120 msec Pacing right ventricle lead in the right ventricular apex (RVA), system implanted within 6 weeks or chronically implanted system with histograms showing 20% or less right ventricle pacing Exclusion Criteria: LVEF greater than 40%, Any rhythm other than sinus rhythm Second degree or higher atrioventricular block Native Heart Rate less than 40 beats per minute or greater than 90 beats per minute Left ventricle or Chronic Sinus lead in non-RVA location Chronically implanted system with greater than 20% right ventricle pacing

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Observation<br>30 Patients with dualchamber pacemakers or implantable cardioverter-defibrillators (ICDs) | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Acute effect of mechanical dyssynchrony measured by septal to lateral wall delay using tissue doppler imaging between baseline non-fused atrioventricular conduction and varying degrees of paced and native atrioventricular conduction. |  |  | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Stroke volume as measured by time velocity integral across the aorta valve between baseline non-fused atrioventricular conduction, and varying degrees of paced and native atrioventricular conduction. |  |  |