Availability of an accurate bedside method to determine right ventricular ejection fraction and size using a flow-directed balloon-tipped catheter would represent a major advance in the hemodynamic monitoring of patients. The thermal technique provides a convenient and inexpensive method for monitoring heart function at the bedside. A catheter (tube) is placed in the right heart through a vein. From this catheter, central venous pressure and pulmonary artery pressure can be measured. By injecting a cold salt solution (saline) and measuring the temperature changes in the pulmonary artery, the amount of blood pumped by the heart per minute can be calculated (cardiac output). This thermodilution technique is easy and reproducible, and has become a standard in clinical care. To this system, the measurement of the right ventricular ejection fraction was added. (RVEF) Precise measurement of ejection fraction has very important prognostic, diagnostic, and therapeutic advantages. However, experimental and clinical studies show that the thermodilution technique consistently underestimates RVEF and grossly overestimated RV end- diastolic volume. In this grant, we will develop a new thermodilution system, which will enable rapid, accurate assessment of right ventricular function. In Phased AMT Inc. will design and fabricate the catheters needed for the cardiac output and RV ejection fraction measurements. AMT and Temple University will collaborate on the computer simulation to test the basic concepts. The system to measure RVEF will be tested and validated in vivo by Dr. Santamore at Temple University. In Phase II, AMT Inc. will develop and build a self-contained electronic system to measure temperatures and calculate cardiac output, RV ejection fraction, RV end-diastolic and end-systolic volumes. PROPOSED COMMERCIAL APPLICATION: Not Available.