INTERNAL THORACIC ARTERY FLOW IN DIABETIC-PATIENTS

Patients with diabetes mellitus have an increased frequency of atheros clerotic coronary artery disease, plus abnormalities of vascular tone that could be contributed to autonomic, platelet, and endothelial dysf unction. The purpose of this prospective study was to compare the inte rnal thoracic artery (ITA) flow of diabetic and nondiabetic patients, to determine whether any pathophysiologic changes occur that have any bearing on vascular tone and the adequacy of flow of the ITA. In a con secutive group of patients undergoing coronary artery bypass graft (CA BG) surgery, 117 patients (group I) were nondiabetic (ND), 18 patients (group II) were noninsulin dependent (NIDDM), and 20 patients (group III) were insulin dependent (IDDM) diabetics. The ITA was mobilized, a nd following systemic heparinization it was divided and trimmed for th e subsequent anastomoses. The first ITA flow measurement was recorded (flow 1). This was followed by an intraluminal injection of 2 mi of di lute papaverine solution (30 mg in 20 mi N/saline), which was enclosed in the artery for fifteen minutes by applying a soft clamp to the dis tal end. At the end of this period, a second flow measurement was take n (flow 2). Percent increase in flow and flow reserve (flow 2/flow 1) were recorded for each patient. The median values for flow 1 were 48, 46, and 58 mL/minute for groups I, II, and III respectively. For flow 2 the values were 132, 118, and 126 for groups I, II, and III, respect ively, with a median percent increase in flow being 138% (47-380%), 17 9% (100-380%), and 115% (35-470%) for groups I, II, and III respective ly (P less than or equal to 0.0001). ITA flow reserve was similar amon g the three groups and was 2.4, 2.8, and 2.2 for groups I, II, and III respectively.