To the Editor:-As an anesthesiologist who cares for patients with severe heart disease, I am attentive to potential clinical intraoperative applications of myocardial ischemic preconditioning. With this technique, the myocardium is protected from ischemic injury by a brief, preceding period of ischemia. There have been experimental, as well as clinical, reports of the benefits of this ischemic preconditioning. Therefore, I read with great interest the recent case report by Latham et al. regarding the intraoperative use of this technique. However, because there was no evidence of myocardial ischemia during the preconditioning interval, there was no evidence that ischemic preconditioning was actually used! Although ischemic preconditioning before bypass grafting was attempted by occlusion of a branch of the circumflex coronary artery, the authors state that “there was no evidence of myocardial ischemia as determined by ST-segment and T-wave changes, and the patient was hemodynamically stable.” Myocardial ischemia may also be inferred from other types of monitoring (e.g., transesophageal echocardiography), but the authors present no data to this effect. Administration of adenosine may confer beneficial effects similar to that of ischemic preconditioning, but the authors' use of adenosine was limited to the interval during, rather than before, coronary bypass grafting. Ischemic preconditioning also was attempted later by occluding a diagonal branch of the left anterior descending coronary artery, but monitoring data during this latter maneuver are not reported. The patient described in the case report received appropriate clinical care. However, there is no evidence that his care included ischemic preconditioning.
Paul Lennon, MD
Department of Anesthesia; Brigham and Women's Hospital; 75 Francis Street; Boston, Massachusetts 02115
(Accepted for publication July 30, 1998.)