Physiological and pharmacological responses of arterial graft flow after coronary artery bypass grafting measured with an implantable ultrasonic Doppler miniprobe

Abstract

Background: The present study was designed to investigate physiological and pharmacological responses of the arterial graft flow measured by the directly implanted ultrasonic pulsed Doppler miniprobe after coronary artery bypass grafting (CABG).

Methods and results: Our original 5-MHz, 5-mm-diameter, Doppler mini-flow probe catheter, which has four silicone brims in front to facilitate its fixation onto the graft without direct suture, was attached onto internal thoracic artery (ITA) and gastroepiploic artery (GEA) grafts during CABG in 10 patients. Approximately 2 weeks postoperatively, when the patient's condition was quite stable without medication, changes of flow velocity in those grafts induced by catecholamine, exercise, taking meals, and coronary vasodilating drugs were measured. Dobutamine significantly increased both ITA and GEA graft flow velocity (p < 0.01), whereas dopamine had no distinct positive effect. Upon the patient taking meals, the GEA graft showed an 83% increase of the flow velocity (p < 0.05), whereas the ITA graft showed no significant change. Walking exercise for 6 minutes increased both grafts' flow velocity up to two times that of control values (p < 0.01). Oral intake of coronary vasodilating drugs showed no significant effect. After the investigation was completed, the probe was removed easily at bedside without difficulty.

Conclusions: Using this implantable Doppler miniprobe, postoperative function in the individual coronary bypass graft under various conditions was effectively investigated.