A laser Doppler catheter for monitoring both phasic and mean coronary vein flow

A new catheter-type laser Doppler velocimeter has been developed to monitor coronary vein flow. A thin graded-index multimode optical fiber (outer diameter of 125 microns) is set inside a 5-F catheter, and eight elastic silicon rubber spikes are arranged radially toward the vessel wall to fix the catheter tip in or near the axial region of the coronary vein. He-Ne laser light (wave length = 632.8nm) is introduced into the blood through the optical fiber, and reflected light is collected by the same fiber. The Doppler signal is detected by a spectrum analyzer. To avoid any effect by the spikes on flow, the fiber is extended from the catheter tip by 3 mm at the time of measurement. Straight and curved tubing was used to examine the accuracy of flow measurement. The flow velocities recorded by the catheter, which were measured by an electromagnetic flowmeter, exhibited excellent linearity (r = straight; 0.982, curved: 0.996). The blood flow velocity in the great cardiac vein was measured by this method in five dogs. The predominantly systolic waveform, which is a characteristic of the coronary vein flow, was observed in all of the dogs. The great cardiac vein velocity increased around the beginning of the ventricular ejection and decreased gradually after the peak formation at mid- or end-diastole. In addition to this main peak, small flow components were frequently observed during isovolumic contraction and the atrial contraction phase, although these flow components varied in individual dogs. Following left anterior descending artery occlusion, the great cardiac vein flow velocity decreased significantly.(ABSTRACT TRUNCATED AT 250 WORDS)