סמינר מחקר בחוג להנדסה ביו רפואית

מר אורן רוטמן, תלמיד המחלקה לדוקטורט:

Effect of Elastic Tubes Distensibility and Stenoses on Pressure Drop in Pulsatile Flow - Toward Application in Arteries

העבודה נעשתה בהנחיית פרופ' שמואל עינב, המחלקה להנדסה ביו-רפואית, אוניברסיטת תל- אביב, ובהנחיית פרופ' אברהם שיצר, הפקולטה להנדסת מכונות, הטכניון.

Abstract:

Blood flow, pressure drop and arterial distensibility are important parameters that are indicative of the coronary arteries patency and atherosclerosis severity. While pressure drop is related to flow, and therefore serves as a functional assessment of a stenosis severity, the arterial distensibility is indicative of the arterial stiffness, and hence the arterial wall composition. In the present study we suggest that local pressure drops are affected by the arterial stiffness, and can therefore provide lesion specific bio-mechanical information on the artery, in addition to functional assessment of the flow.

The objectives of the study are (a) to develop a method for high accuracy pressure drop measurements using a catheter; (b) to investigate the correlation between the fluid pressure drop and the arterial distensibility for different cases of stenosis severity and flow; (c) to introduce a new parameter for combined functional and bio-mechanical assessment of arteries, which is solely based on pressure drop measurements; and, (d) to compare the new parameter to the Functional Flow Reserve (FFR) indicator.

The investigation methods include: (a) in-vitro wet experiments on silicone mock arteries, and (b) Numerical Fluid Structure Interaction (FSI) simulations. Highly accurate pressure drop measurements (±0.05 mmHg) are performed with fluid-filled double-lumen catheter using a validated signal restoration method that has been developed in our lab specifically for this study. The in-vitro experiments indicate that our accurate pressure drop measurement method facilitates the differentiation among several levels of arterial stiffnesses, with distensibility ranging from 1-10%. Local pressure drops are markedly affected by the arterial stiffness, and these changes in pressure drop can be detected even in small to intermediate size stenoses, where the FFR values remain 0.99. Our results indicate the potential of a high accuracy pressure drop-based parameter to be superior to FFR. Such a parameter will provide cardiovascular interventionalists with lesion specific bio-mechanical and functional data, for improved real time decision making in the cath-lab.