Clinical trial NCT00508196: Endothelial Function and Cardiac Output in RV Pacing
Official title: Endothelial Function and Cardiac Output in Right Ventricular Pacing
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: NA
Conditions: Bradycardia
Keywords: right ventricular pacing
endothelial function
cardiac output
Lead sponsor: University of Dundee
Sponsor class: OTHER
First posted: 2007-07-27
Enrollment: 22
Sex: ALL
Minimum age (years): 21
Maximum age (years): 85
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: no
Allocation: RANDOMIZED
Intervention model: CROSSOVER
Primary purpose: TREATMENT

Brief summary: 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.

Detailed description: 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.

Eligibility criteria: Inclusion Criteria:

* Dual chamber pacemaker
* Intact AV node function

Exclusion Criteria:

* Unstable angina, heart failure
* Inability to exercise

Primary outcomes:
measure: Endothelial Function Assessed by Flow Mediated Vasodilatation
timeFrame: 1 week
Secondary outcomes:
measure: B-type Natriuretic Pepetide
timeFrame: 1 week
measure: Cardiac Output
timeFrame: 1 week
Other outcomes:
Locations:
city: Dundee
country: United Kingdom
facility: Ninewells Hospital and medical School
Study officials:
affiliation: University of Dundee
name: Allan Struthers, MD
role: STUDY_DIRECTOR
References: