Electromechanical heart function
Abstract
Heart failure (HF) and coronary artery disease (CAD) are two common conditions related to cardiovascular disease. Cardiac resynchronization therapy (CRT) has been shown to be effective for improving the HF condition. However, approximately 30% of patients that receive CRT show no improvements with the therapy. The role of pacing site and myocardial viability in CRT response is not completely understood. This study hypothesized that site-specific bi-ventricular (BiV) pacing is important for both local and global improvements during normal perfusion and myocardial ischemia. To test this hypothesis, coronary blood flow to the anterior portion of the left ventricle (LV) was controlled in open-chest canines during right atrial, right ventricular (RV), and BiV pacing at either the lateral (LW) or anterior (AW) LV wall. Local EM function, along with global hemodynamic parameters, were measured during pacing at normal perfusion (100% flow), moderate ischemia (50% flow), and severe ischemia (25% flow). The results showed that severe ischemia caused local and global EM dysfunction, despite consistent timing of electrical events. RV and BiV pacing at any location were not effective in improving LV performance during severe ischemia. BiV-AW and RV pacing disrupted local and global function at all perfusion pressures. During normal perfusion and moderate ischemia, BiV-LW pacing improved local function in the experimental region and improved overall LV performance, despite no improvement in QRS duration. The results of these studies show that coronary perfusion and pacing site are important parameters for CRT response. Future studies related to this work in man may be useful for improving CRT response and patient outcomes.
Degree
Ph.D.
Advisors
Talavage, Purdue University.
Subject Area
Biomedical engineering
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