Noninvasive Graft Flow and Patency Assessment Following Minimally Invasive Direct Coronary Artery Bypass (MIDCAB) Grafting

(#1999-6000 ... May 21, 1999)

Hyung J. Chun, AB¹, John R. Doty, MD¹, Jorge D. Salazar, MD¹, Janis Richmond, RN², James D. Fonger, MD²

¹Division of Cardiac Surgery, Johns Hopkins Hospital, Baltimore, MD ²Department of Cardiac Surgery, Washington Adventist Hospital, Takoma Park, MD

ABSTRACT

Objective: Assessment of graft patency following minimally invasive direct coronary artery bypass (MIDCAB) surgery is essential in order to determine the efficacy of this technique. This study was conducted to evaluate the role of intraoperative and postoperative noninvasive flow and velocity measurements to follow and predict graft performance.

Methods: Between April 1996 and July 1997, 130 patients had 133 grafts placed using MIDCAB techniques. Intraoperative transit-time ultrasound was used to assess graft patency and flow prior to wound closure. Also, serial transcutaneous doppler examinations were performed to evaluate graft patency on the first postoperative day, at two weeks, and at three months. Peak values for systolic and diastolic waveforms were measured for both flow and velocity, and the diastolic-to-systolic ratio was calculated at each time interval. Recatheterization was performed selectively for inadequate ultrasound flow or doppler velocity, or for patient symptoms.

Results: Seven (5.3 %) grafts developed stenosis or occlusion. When compared to normal grafts, mean intraoperative flows, flow ratios, and velocity ratios were lower. Mean postoperative diastolic peak velocity (DPV) to systolic peak velocity (SPV) ratio remained stable over time for normal grafts; however, grafts with stenosis or occlusion demonstrated a diminished DPV/SPV ratio.

Conclusions: Intraoperative transit-time ultrasound and outpatient transcutaneous doppler examinations did not reach a predictive value for graft stenosis or occlusion following MIDCAB surgery in this series of patients. However, these data demonstrate trends that may help identify patients at an increased risk for unfavorable events, guiding the use of postoperative recatheterization in such patients.

AUTHOR/ARTICLE INFORMATION

Presented at the Second Annual Meeting of the International Society for Minimally Invasive Cardiac Surgery, Palais dés Congres, Paris, France , May 21-22, 1999.

Reprint requests to: James D. Fonger, MD, Washington Adventist Hospital, Suite 440, 7610 Carroll Ave, Takoma Park, MD 20912; Phone (703)902-8401; Fax: (703)902-8401; Email: jfonger@heartnet.org

Submitted on: Peer reviewed and accepted at the International Society for Minimally Invasive Cardiac Surgery's 2nd Annual Meeting and Scientific Sessions, Paris, France, May 21-22 1999.

Keywords: MIDCAB, Minimally Invasive Direct Coronary Artery Bypass, Noninvasive Graft Assessment