Internal Thoracic Artery Flow in Diabetic Patients

Abstract

Patients with diabetes mellitus have an increased frequency of atherosclerotic coronary artery disease, plus abnormalities of vascular tone that could be contributed to autonomic, platelet, and endothelial dysfunction. The purpose of this prospective study was to compare the internal 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 consecutive group of patients undergoing coronary artery bypass graft (CABG) 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, and following systemic heparinization it was divided and trimmed for the subsequent anastomoses. The first ITA flow measurement was recorded (flow 1). This was followed by an intraluminal injection of 2 mL of dilute papaverine solution (30 mg in 20 mL N/saline), which was enclosed in the artery for fifteen minutes by applying a soft clamp to the distal end. At the end of this period, a second flow measurement was taken (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, respectively, with a median percent increase in flow being 138% (47-380%), 179% (100-380%), and 115% (35-470%) for groups I, II, and III respectively (P < 0.0001). ITA flow reserve was similar among the three groups and was 2.4, 2.8, and 2.2 for groups I, II, and III respectively. The ITA exhibits the same degree of initial spasm, similar relaxation to intraluminal papaverine, and similar flow reserve. No physiologic abnormalities of ITA flow and reactivity are specific to diabetes. The ITA should be used with the same indications or contraindications as in nondiabetic patients.