A Review of Transit-time Flow Measurement for Assessing Graft Patency

(#1999-11518 ... June 29, 1999)

Daniel J. VanHimbergen, BA, Steven C. Koenig, PhD, Saad F. Jaber, MD, Patricia B. Cerrito, PhD, Paul A. Spence, MD

Department of Surgery, Jewish Hospital Heart and Lung Institute, University of Louisville School of Medicine, Louisville, Kentucky 40202

ABSTRACT

Anastomotic quality is a critical issue in minimally invasive coronary artery bypass surgery, particularly "off-pump". It is important to detect a "poor" anastomosis during the procedure so future re-operation can be avoided. Methods such as intraoperative angiography, thermal angiography, probing of the anastomosis, and graft flow measurement have been used intraoperatively to help identify anastomotic errors. With the evolution of stabilizers, graft patency rates for off-pump cases have improved, but many believe they are still not as high as those of the conventional procedure. For off-pump surgery to be accepted and practiced universally, patency rates must be equivalent to those of "on-pump" cases. Transit-time flow measurement has become an increasingly popular non-invasive method for assessing anastomotic quality. However, it is difficult to establish whether an anastomosis is patent based on mean graft flow alone. Spectral analysis of graft flow waveforms reveal characteristic patterns that identify intermediate ranges of stenosis between fully patent and totally occluded. Together, these two components of graft flow have been used in the construction of a neural network to help identify "faulty" anastomoses. Transit-time flow measurement is a non-invasive tool that can be beneficial in identifying fully patent or nearly occluded grafts, and may also help in distinguishing intermediate stenoses.

AUTHOR/ARTICLE INFORMATION

Presented at the Minimally Invasive Total Myocardial Revascularization conference, Tampa, Florida, March 19-20, 1999.

Paul A. Spence, MD, Department of Surgery, Jewish Hospital Heart and Lung Institute, 500 South Floyd Street, University of Louisville, Louisville, Kentucky 40202, Phone: 502-852-4838, Fax: 502-852-1795

Submitted on: June 28, 1999; Accepted on: June 29, 1999

Keywords: Anastomotic Quality, Off-pump CABG, Transit-time flow, flow measurement, patency, MIDCAB