平尾 健一¹, 水重 克文¹, 近藤 功¹, 高木 雄一郎¹, 辻 哲平¹, 千田 彰一², 松尾 裕英¹

Kenichi HIRAO¹, Katsufumi MIZUSHIGE¹, Isao KONDO¹, Yuichiro TAKAGI¹, Teppei TSUJI¹, Shoichi SENDA², Hirohide MATSUO¹

¹香川医科大学第2内科, ²香川医科大学総合診療部

¹Second Department of Internal Medicine, Kagawa Medical University, ²Department of Integrated Medicine, Kagawa Medical University

キーワード : Coronary flow reserve, Insulin resistance, Microvascular dysfunction, Obesity, Transthoracic Doppler echocardiography

Background. Coronary flow reserve (CFR) has been considered to be an important indicator of coronary microvascular function in the absence of coronary artery stenosis. Although the reduction of CFR has been described in patients with diabetes mellitus, there are few data from patients with insulin resistance. Recent technological advances in transthoracic Doppler echocardiography (TTDE) have made noninvasive measurement of coronary flow velocity in the distal portion of the left anterior descending artery (LAD) possible.
Objectives. We attempt to use TTDE to examine coronary microvascular function in patients with insulin resistance.
Methods. The study population consisted of 6 patients with normal glucose tolerance (NGT), 14 with insulin resistance and Body Mass Index values in excess of 26.4 (IR), and 14 with non-insulin-dependent diabetes mellitus (DM). Cases of IR were assorted into two subgroups: those with complications (IR-C) and those without complications (IR-nC). No patient showed evidence of myocardial infarction, angina pectoris, cardiomyopathy, or significant ST-T change during the treadmill exercise stress test or dobutamine stress echocardiography. Coronary flow velocity at the distal LAD was recorded using a digital TTDE system with a high frequency (7 MHz) transducer at rest and during hyperemia induced by intravenous infusion of adenosine (0. 14 mg/kg per minute) under the guidance of color Doppler flow mapping.
Results. Adequate spectral Doppler recordings of coronary flow were obtained in 29 (85%) of 34 subjects. CFR was defined as the ratio of peak diastolic coronary flow velocity at hyperemia to the baseline value. CFRs in IR-C were similar to those in DM (2.0±0.2 vs 2.2±0.4, n.s.) and lower than those in NGT (3.5±0.6)(p Conclusions. Insulin resistance was not an important risk factor in the reduction of CFR. Also, TTDE was a feasible method for noninvasive assessment of CFR in patients with IR and DM.