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Eur J Cardiothorac Surg 2006;30:873-876
© 2006 Elsevier Science NL

Vacuum-assisted apical suction devices induce passive electrical changes consistent with myocardial ischemia during off-pump coronary artery bypass graft surgery

^a Department of Anesthesiology, The Ohio State University, Columbus, OH 43210, USA
^b Department of Electrical & Computer Engineering, The Ohio State University, Columbus, OH 43210, USA
^c Division of Cardiothoracic Surgery, The Ohio State University, Columbus, OH 43210, USA
^d Center for Biostatistics, The Ohio State University, Columbus, OH 43210, USA
^e Department of Cardiothoracic Surgery, Montefiore Medical Center, Bronx, NY, USA

Received 10 April 2006; received in revised form 1 September 2006; accepted 4 September 2006.

^_* Corresponding author. Address: Department of Anesthesiology, The Ohio State University, 410 West 10th Avenue, Columbus, OH 43210, USA. Tel.: +1 614 293 5675 (O); fax: +1 614-293-8153. (Email: dzwonczyk.1{at}osu.edu).

Objective: Off-pump coronary artery bypass graft surgery is common therapy to completely revascularize diseased hearts. In order to graft posterior arteries in this procedure, the heart must be lifted from the chest cavity and manipulated to expose the surgical field using an apical suction device. This suction device may cause unwanted myocardial ischemia. Methods: In this observational study, we measured myocardial electrical impedance, a parameter that responds to myocardial ischemia, as well as ST-segment changes during off-pump coronary artery bypass graft surgery in 12 patients with two-vessel coronary artery disease undergoing revascularisation of the left anterior descending and the posterior descending coronary arteries. During the posterior descending artery revascularisation phase of the procedure the apical suction device was oriented over the electrodes used to measure myocardial electrical impedance, thus allowing us the opportunity to assess myocardial ischemia in this region of the heart. Results: In these 12 patients, myocardial electrical impedance progressively increased under the suction device during posterior coronary artery revascularisation, suggesting that myocardial ischemia developed in this region of the myocardium. ST-segment changes were negligible while the heart was vertically displaced (and the suction device attached), but increased immediately when the heart was returned to the neutral anatomical position. Conclusion: Our data suggest that the apical suction device may cause ischemia while the heart is vertically displaced and electrically disconnected from the body. Under these conditions, ST-segment changes may not detect myocardial ischemia. Myocardial electrical impedance has the potential to reliably detect intraoperative myocardial ischemia under these circumstances.

Key Words: Myocardial electrical impedance • Apical suction devices • Off-pump coronary artery bypass surgery • Myocardial ischemia