title: Comparison of perioperative and postoperative phasic blood flow in aortocoronary venous bypass grafts by means of pulsed Doppler echocardiography with implantable microprobes.
abstract: Although graft dimension and hemodynamic variables have been suggested as important determinants of the functional results of aortocoronary bypass grafting, there is no easy-to-use bedside method of monitoring phasic blood flow in coronary bypass grafts. We developed a miniaturized implantable silicone pulsed Doppler flow probe linked to a classic 8 MHz pulsed Doppler system. This apparatus has an adjustable range-gated time system that permits accurate measurement of diameter (D, in mm), cross-sectional blood flow velocity (Vm, in cm/sec), and coronary bypass graft flow (CBGF, in ml/min) as pi D2/4 X Vm X 60. Ten patients (55 +/- 7.2 years SD) with preoperative left ventricular ejection fractions over 45% received the implantable flow probes during the aortocoronary venous bypass procedure. Closure of the chest altered systolic and diastolic components of flow velocity and CBGF decreased from 131 +/- 65.8 to 94 +/- 55 ml/min (-28%; p less than .01). Comparison between early postoperative values (intensive care unit) and values 6 days later showed significant increases in diameter from 4.2 +/- 0.9 to 5.3 +/- 0.9 mm (p less than .01) and in CBGF from 130 +/- 112 to 204 +/- 86 ml/min (p less than .01). We conclude that the implantable pulsed Doppler microprobe is a sensitive bedside method for monitoring aortocoronary bypass graft diameter and blood flow in the postoperative period.
mesh_terms: D001783:Blood Flow Velocity; D001026:Coronary Artery Bypass; D004452:Echocardiography / Q000295:instrumentation; D004567:Electrodes, Implanted; D006801:Humans; D007432:Intraoperative Period; D008839:Microelectrodes; D008875:Middle Aged; D011184:Postoperative Period; D012501:Saphenous Vein / Q000503:physiopathology / Q000637:transplantation*