Date of Award

Fall 1999

Document Type

Thesis

Degree Name

Master of Science in Biomedical Engineering - (M.S.)

Department

Biomedical Engineering Committee

First Advisor

R. S. Sodhi

Second Advisor

David S. Kristol

Third Advisor

John Tavantzis

Abstract

Conventional IABP timing deflates 100% of the balloon volume before the onset of left ventricular ejection and has been well established in the literature as a safe and effective method. Yet, recent studies suggest that deflation of the IAB at or near the onset of systole improve myocardial efficiency (Kern, 1999, 1129). To test whether deflation of the JAB at a later deflation time reduces left ventricular workload and enhances coronary perfusion, four timing methods were evaluated in 20 patients: T1 (100% JAB volume deflated before onset of ejection), T2 (60% IAB volume deflated before and 40% volume during ejection), T3 (25% IAB volume deflated before and 75% volume during ejection) and T4 (100% deflation simultaneous with left ventricular ejection).

To identify an optimal timing point for the deflation of the JAB, data was analyzed. Data analysis consisted of three main parts: elimination of files containing noise artifact, normalization of data for ease of analysis, and correction for variations in mean aortic pressure and heart rate which take into account the dynamic state of the heart. Late LAB deflation at 50% of the volume deflated prior to left ventricular ejection produced significantly greater percentage changes in systolic pressure time index (SPTI), diastolic pressure time index (DPTI), the SPTI/DPTI ratio, systemic vascular resistance (SVR) as compared to conventional timing, T1. No significant change in heart rate or cardiac output was established.

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