Masatoshi Nagayama, M.D., Yoshinori Fujita, M.D., Takayuki Kanai, M.D., Tomohiro Yamada, M.D., Kazuo Tozawa, M.D., Motomi Ushiyama, M.D., Akira Saito, M.D., Youichi Takeyama. M.D., Takeshi Hasegawa, M.D. and Takashi Katagiri, M.D.

Abstract
Changes in myocardial lactate metabolism during ramp exercise were investigated through great cardiac vein catheterization in 15 patients with effort angina (EA) and 7 patients with microvascular angina (MVA). The exercise test was performed using a supine bicycle ergometer. Blood samples were obtained from the great cardiac vein (GCV) and the radial artery each minute during exercise. Patients in the EA group showed a point at which the lactate extraction ratio (LER) and the ST level decreased rapidly during exercise. This point was clearly recognized in 12 of 13 patients, and may represent the ischemic threshold. Both the LER and ST level showed similar changes during exercise, and these values were significantly different between the ischemic threshold and peak exercise (p<0.01). Both the LER and ST level were strongly correlated with the duration of exercise until the threshold (r=0.703). In the MVA group, both the LER and ST level during exercise continuously decreased throughout exercise without an ischemic threshold in all of the subjects. Endomyocardial biopsy revealed sclerosis of small arteries in the myocardium in all of the patients. In both effort angina and microvascular angina, a close correlation was noted between the change in ST and that in the myocardial lactate extraction ratio.
(Jpn Circ J 1996; 60: 876-888)

Key Words: Lactate, Ramp exercise, Effort angina, Microvascular angina

Mailing address: Masatoshi Nagayama, M.D., Third Department of Internal Medicine, Showa University School of Medicine, 1-5-8 Hatanodai Shinagawa-ku, Tokyo 142, Japan