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Pacing from the right ventricle (as is current practice in patients implanted with permanent pacemakers for bradycardia), has been associated with worse outcomes particularly in heart failure patients. Recent clinical trials suggest that chronic right ventricular pacing (VP) is associated with worsening heart failure, increased strokes and atrial fibrillation. Hemodynamically, right VP results in delayed activation and contraction of the LV which can give rise to functional mitral regurgitation, shortened diastolic filling time and thus reduced coronary filling, as well as abnormal arterial pulsatile flow. The mechanisms for the deleterious effects of right VP in heart failure patients have not been previously investigated. Our aim of this study is therefore to investigate the hemodynamic effects of right VP in stable heart failure patients in terms of exercise cardiac output (CO, an important measure of myocardial function and prognosis), as well as endothelial function which may be deranged as a result of abnormal arterial pulsatile flow.
Study Aims The aim of this study is to investigate the effect of right ventricular pacing on CO at rest and exercise, and on endothelial function and B-type natriuretic peptide, BNP, in patients with heart failure.
Methods: Thirty patients with dual chamber pacemakers for sinus node disease will be recruited: 15 controls with normal LV function and 15 with stable impaired LV function (ejection fraction <40%). The pacemaker will be programmed to pace to back-up pacing at 55bpm in the atrial only (AAI, no right VP) for one week (baseline); and than programmed to overdrive pacing at 70-80bpm, randomised to either to dual chamber, DDD (sequential atrial and ventricular pacing) with a short AV delay (to ensure maximal right VP) or AAI (no RV pacing), for 1 week. There will be a crossover after a 1 week washout at backup AAI pacing at 55 bpm. Resting and exercise CO will be measured at the end of each pacing mode intervention using the Inocor system (a validated non invasive method of CO measurement, using inhaled inert gas equilibriums). Endothelial function will be measured non-invasively at the same time points, as will plasma BNP, a measure of LV strain. Patients with unstable heart failure or angina will be excluded.
Study Endpoints: Rest and exercise CO; and endothelial function and BNP with and without RV pacing, in patients with preserved and impaired LV function.
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| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| RVP-min | Other | DDD pacing with long AV delay |
| |
| RVP-max | Other | DDD pacing with short AV delay |
|
| Measure | Description | Time Frame |
|---|---|---|
| Endothelial Function Assessed by Flow Mediated Vasodilatation | Flow mediated vasodilatation as measured by reactive hyperaemia peripheral arterial tonometry signal using EndoPAT software, Itamar. A post-occlusion to pre-occlusion ratio is calculated by the EndoPAT software, providing the EndoPAT index (EnFI) | 1 week |
| Measure | Description | Time Frame |
|---|---|---|
| B-type Natriuretic Pepetide | 1 week | |
| Cardiac Output | measured at peak exercise on a standard exercise bicycle, measured non-invasively using the inert gas rebreathing technique (Innocor, Innovision A/S, Odense, Denmark). |
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Inclusion Criteria:
Exclusion Criteria:
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| Name | Affiliation | Role |
|---|---|---|
| Allan Struthers, MD | University of Dundee | Study Director |
| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| Ninewells Hospital and medical School | Dundee | DD1 9SY | United Kingdom |
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Prior to randomization, as pre-study right ventricular pacing was variable among the subjects, pacing was programmed to produce minimal right ventricular pacing (using single-chamber atrial pacing or dual-chamber mode with long AV delay) for a minimal washout period of ≥1 week.
Subjects previously implanted with a dual-chamber pacemaker for SND were recruited from the Ninewells Hospital and Medical School pacemaker clinic. No subject was pacemaker dependent and the indication for pacing was intermittent sinus arrest or sinus bradycardia.
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| ID | Title | Description |
|---|---|---|
| FG000 | RVP-Max First, Then RVP-Min | maximum RV pacing programmed (short AV delay) for 1 week, then at least 1 week washout, then minimum RV pacing (long AV delay) |
| FG001 | RVP-Min First, Then RVP-Max | Minimum RV pacing programmed (long AV delay) for 1 week, then at least 1 week washout, then maximum RV pacing (short AV delay) |
| Title | Milestones | Reasons Not Completed | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Overall Study |
|
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| ID | Title | Description |
|---|---|---|
| BG000 | All Participants | All subjects had the right ventricular lead implanted at the right ventricular apex. No subject was pacemaker dependent and the indication for pacing was intermittent sinus arrest or sinus bradycardia. Subjects with ongoing angina or heart failure symptoms, known AV node disease, bundle branch block, age >80 years, atrial fibrillation, or inability to exercise, were excluded. |
| Units | Counts |
|---|---|
| Participants |
|
| Title | Description | Population Description | Parameter Type | Dispersion Type | Unit of Measure | Calculate Percentage | Denominator Units Selected | Denominators | Classes |
|---|---|---|---|---|---|---|---|---|---|
| Age, Continuous | Mean |
| Type | Title | Description | Population Description | Reporting Status | Anticipated Posting Date | Parameter Type | Dispersion Type | Unit of Measure | Calculate Percentage | Time Frame | Units Analyzed | Denominator Units Selected | Arm/Group Information | Denominators | Classes | Analyses | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Primary | Endothelial Function Assessed by Flow Mediated Vasodilatation | Flow mediated vasodilatation as measured by reactive hyperaemia peripheral arterial tonometry signal using EndoPAT software, Itamar. A post-occlusion to pre-occlusion ratio is calculated by the EndoPAT software, providing the EndoPAT index (EnFI) | Posted | Mean | Standard Deviation | EndoPAT index (EnFI) | 1 week |
|
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| ID | Title | Description | Deaths (Affected) | Deaths (At Risk) | Serious Events (Affected) | Serious Events (At Risk) | Other Events (Affected) | Other Events (At Risk) |
|---|---|---|---|---|---|---|---|---|
| EG000 | RVP-min | Minimal RV pacing , with long AV delay programmed in DDD mode | 0 |
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| Title | Organization | Phone | Extension | |
|---|---|---|---|---|
| DR Anna Maria Choy | University of Dundee | 01382 383482 | a.choy@dundee.ac.uk |
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| ID | Term |
|---|---|
| D001919 | Bradycardia |
| ID | Term |
|---|---|
| D001145 | Arrhythmias, Cardiac |
| D006331 | Heart Diseases |
| D002318 | Cardiovascular Diseases |
| D010335 | Pathologic Processes |
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| 1 week |
| years |
|
| Sex: Female, Male | Count of Participants | Participants |
|
| Race (NIH/OMB) | Count of Participants | Participants |
|
| Units | Counts |
|---|---|
| Participants |
|
|
| Secondary | B-type Natriuretic Pepetide | Posted | Mean | Standard Deviation | microgrammes /L | 1 week |
|
|
|
| Secondary | Cardiac Output | measured at peak exercise on a standard exercise bicycle, measured non-invasively using the inert gas rebreathing technique (Innocor, Innovision A/S, Odense, Denmark). | Posted | Mean | Standard Deviation | L/min | 1 week |
|
|
|
| 22 |
| 0 |
| 22 |
| 0 |
| 22 |
| EG001 | RVP-Max | Maximum RV pacing with short AV delay programmed in DDD mode | 0 | 22 | 0 | 22 | 0 | 22 |
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| D013568 |
| Pathological Conditions, Signs and Symptoms |