Turbulent stresses in the region of a Hancock porcine bioprosthetic aortic valve.

The purpose of this study was to measure stresses associated with turbulence (Reynolds stresses), in the region of a 29-mm-dia porcine bioprosthetic valve (Hancock, Model 242). Studies were performed in an in vitro pulse duplicating system with the valve mounted in the aortic position. The Reynolds stresses were calculated from velocities obtained with a two channel laser Doppler anemometer.

Identification of peripheral vascular disease with real-time ultrasonic imaging.

Real-time ultrasonic imaging can provide useful clinical information in subjects with peripheral vascular disease. This report outlines the technique of imaging the extracranial arterial system and arterial segments that supply the lower extremities. It describes our interpretation of the ultrasonic image as it relates to the pathology of fatty streaks, smooth and complex plaques, occlusions and thrombus formations.

Estimation of Reynolds shear stresses during pulsatile flow in the region of aortic valves.

Some investigators have attempted to estimate the Reynolds shear stress on the basis of a single component of velocity. The purpose of this investigation is to determine the validity of such estimates in a complex flow field, such as occurs in the cardiovascular system in the region of the aortic valve. Turbulent velocities were obtained in an in vitro pulse duplicating system with a two-channel laser Doppler anemometer.

Patterns of flow in the left coronary artery.

The purpose of this investigation is to describe our preliminary observations of the overall pattern of flow in a mold of the left coronary artery of a pig. Flow in the coronary mold was visualized by the injection of dye into the sinus of Valsalva. Studies were performed during steady flow at rates of 100, 200, 300, 400, and 500 mL/min.

Wall shear stress during pulsatile flow distal to a normal porcine aortic valve.

The shear stress at the wall has been of interest as one of the possible fluid dynamic factors that may be damaging in the region of prosthetic valves. The purpose of this study was to measure the axial wall shear stresses in the region of a 29 mm tissue annulus diameter porcine stent mounted prosthetic aortic valve (Hancock, Model 242). Studies were performed in an in vitro pulse duplicating system.