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Flow-mediated, endothelium-dependent dilatation of the brachial arteries is impaired in patients with coronary spastic angina
American Heart Journal Founded in1925
March 1997 Volume 133, Number 3
CLINICAL INVESTIGATIONS
Acute Ischemic Heart Disease
Flow-mediated, endothelium-dependent dilatation of the brachial arteries is impaired in patients with coronary spastic angina Takeshi Motoyama, MD, Hiroaki Kawano, MD, Kiyotaka Kugiyama, MD, Ken Okumura, MD, Masamichi Ohgushi, MD, Michihiro Yoshimura, MD, Osamu Hirashima, MD, and Hirofumi Yasue, MD
Kumamoto, Japan Coronary spasm is induced by acetylcholine, serotonin, ergonovine, or histamine, all of which cause vasodilation when the endothelium is intact, and is promptly relieved by nitroglycerin, which vasodilates through the direct action on smooth muscle. Endothelial dysfunction is therefore possibly involved in the pathogenesis of coronary artery spasm. The aim of this study was to determine whether endotheliurn-dependent vasodilation is impaired in the peripheral arteries of patients with coronary spastic angina. Flow-dependent vasodilaUon of the brachial arteries during reactive hyperemia after the transient arterial occlusion was examined by using the high-resolution ultrasound technique in 35 patients with coronary spastic angina and 35 controls. Flowdependent vasodilation of the brachial arteries was impaired in patients with coronary spastic angina compared with controls (5.9% ± 4.2% vs 9.6% ± 3.4%, p < 0.001) although the percent increase in blood flow during reactive hyperemia was not different between the two groups. The dilator response to nitroglycerin was preserved in patients with coronary spastic angina compared with controls (18.6% ± 5.1% vs 16.2% ± 3.9%, p < 0.04). The results indicate that endothelium-dependent vasodilation of the brachJal arteries is impaired in patients with coronary spastic angina. Thus endothelial vasomotor dysregulation may also be present in the systemic arteries as well as coronary arteries in patients with coronary spastic angina. (Am Heart J 1997;133:263-7.) From the Division of Cardiology, Kumamoto University School of Mediciae. Supported in part by grants-in-aid for Scientific Research on Priority Area (03268107), B03454257, and C3670460 from t h e Ministry of Education, Science, and Culture in Japan, and the Smoking Research Foundation, Tokyo, Japan. Received for publication May 14, 1996; accepted Aug. 8, 1996. Reprint requests: Hirofumi Yasue, MD, Division of Cardiology, Kumamoto University School of Medicine, Honjo 1-1-1, Kumamoto City, Japan 860. Copyright © 1997 by Mosby-Year Book, Inc. 0002-8703/97/$5.00 + 0 4/1/78084
Coronary spasm plays an important role in the pathogenesis of variant angina and ischemic heart disease in general, including other forms of angina pectoris, acute myocardial infarction, and sudden death. TM However, the precise mechanism by which coronary spasm occurs remains unknown. Coronary spasm is induced by acetylcholine, serotonin, ergonovine, or histamine, all of which cause vasodilation when the endothelium is intact, and is promptly relieved by nitroglycerin, which vasodilates through the direct action on smooth muscle. 5-7 The impairment of endothelium-dependent vasodilation is therefore possibly involved in the pathogenesis of coronary artery spasm, s, 9 Flow-dependent vasodilation is known to have an important role in the regulation of the arterial tone at rest and exercise. 1°-13 We have shown that spasm arteries show increased basal tone and do not dilate, but constrict at exercise, and that the increased arterial tone is an important contributor to the anginal attack in patients with coronary spastic angina. 14, 15 Flow-mediated, endothelium-dependent arterial relaxation may therefore conceivably be impaired in patients with coronary spastic angina. As a matter of fact, we demonstrated that a diffuse, nonlocalized disorder in vasom0tility , including endothelium-dependent vasodilation, is involved in the pathogenesis of coronary spastic angina. 15 Furthermore, we have recently found that a missense mutation in endothelial nitric oxide synthase is frequently associated with patients with coronary spastic angina. 16 Therefore 263
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Motoyama et al.
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20
400 p < 0.001 i
P = NS
¢
,= 300
i
.= 1C
200 100
0
CSA Controls
0
CSA Controls
Fig. 1. Percent increase in brachial arterial diameter during reactive hyperemia (left) and percent increase in brachial blood flow observed immediately after cuff deflation (peak reactive hyperemia) ( r i g h t ) in 35 patients with coronary spastic angina ( C S A ) and 35 controls.
Table L Characteristics of study patients CSA (n = 35)
Age (yr) Men/women No. of smokers (%) Total cholesterol (mg/dl) HDL cholesterol (mg/dl)
Controls (n = 35)
61.9 -+ 13.9 61.1 -+ 11.9 16/19 16/19 18 (51.4) 14 (40.0) 180.5 _+28.0 182.1_+26.8 52.9 +_14.1
51.5 _+12.6
Table ]L Baseline values of mean blood pressure, heart rate, brachial diameter, and brachial blood flow p Values
NS NS NS NS NS
Values are expressed as mean -+ SD. CSA, Coronary spastic angina; HDL, high-density lipoprotein; NS, not significant.
the d i s t u r b a n c e of v a s o m o t o r regulation m a y exist in the systemic arteries as well as coronary arteries in p a t i e n t s w i t h c o r o n a r y spastic angina. This s t u d y was designed to examine by u l t r a s o u n d technique w h e t h e r flow-dependent vasodilation during reactive h y p e r e m i a is i m p a i r e d in the brachial arteries in patients with coronary spastic a n g i n a as c o m p a r e d with controls.
METHODS Patients. The study included 35 patients with coronary spastic angina (mean age 61.9 years, range 33 to 77 years, 16 men) in whom episodes of spontaneous angina occurred at rest. All the patients with coronary spastic angina had angiographically normal coronary arteries and showed angiographically documented coronary spasm associated with ischemic ST-segment changes after the intracoronary injection of acetylcho]ine, as previously reported. 5 The study also included 35 control subjects (mean age 61.1 years, range 32 to 76 years, 16 men). These control subjects were selected to match the risk factors for atherosclerosis to those in patients with coronary spastic angina (Table I). The control subjects underwent diagnostic cardiac catheterization for evaluation of chest pain. They had anglo-
CSA (n = 35)
Controls (n = 35)
Mean blood pressure 87.5 -- 9.3 87.4 _+9.5 (ram Hg) Heart rate (beats/min) 60.1 _+9.4 63.7 _+9.0 Diameter (ram) 3.77 _+0.55 3.87 _+0.51 Blood flow (m]/min) 188.6 _+69.5 196.2 + 67.9
p Values
NS NS NS NS
Values are expressed as m e a n -+ SD. CSA, Coronary spastic angina; NS, not significant.
graphically normal coronary arteries and did not show coronary spasm after the intracoronary injection of acetylcholine. All 70 subjects were normotensive (blood pressure <160/90 mm Hg), did not have diabetes, and had plasma total cholesterol <240 mg/dl. These risk factors for atherosclerosis have been shown to be associated with impairment of endothelium-dependent vasodilation. 17 Cigarette smoking, which is a significant risk factor for coronary spastic angina in Japan, is also has been shown to be associated with impairment of endothelium-dependent vasodilation. 19 Therefore we studied all 70 subjects, including smokers, at first. We further studied 38 subjects, excluding smokers from the original 70 subjects. No patients had previous myocardial infarction, congestive heart failure, or other serious disease. Written informed consent was obtained from all patients before the study. The study was in agreement with the guidelines approved by the ethics committee at our institution. Study design. We obtained scans in each brachial artery with high-resolution ultrasound from all 70 study subjects. All medications except sublingal nitroglycerin were withdrawn at least 3 days before the study. No study patients had taken nitroglycerin within 6 hours before the study. The study was performed at 6 AMwhile the patients were fasting because coronary spasm often occurs in the early morning. 14 The vasodilator responses in the brachial arteries were measured by the ultrasound technique pre-
Volume 133, Number 3 American Heart Journal
viously validated by Celermajer et al. 17,19,20 The diameter of the brachial artery was measured from B-mode ultrasound images with a 7.5 MHz linear array transducer (model SSH-160A ultrasound system, Toshiba Corp., Tokyo). 21 The flow velocity of the brachia] artery was measured with a pulsed Doppler signal at a 70-degree angle to the vessel, with the range gate (1.5 mm) in the center of the artery. The brachial artery was longitudinally scanned in the antecubital fossa. Gain setting was optimized at the beginning of the study and was kept constant throughout the recording period. When a satisfactory transducer position was found, the surface of the skin was marked and the arm remained in the same position throughout the study. The subjects lay quietly for 10 minutes before the scan. After baseline measurements of the diameter and the flow velocity in the brachial artery, a blood pressure cuff placed around the forearm was inflated with a pressure of 250 to 300 mm Hg. After 4.5 minutes, the cuffwas released. Diameter and flow velocity were continuously measured during and after cuff deflation. Thereafter the subjects lay quietly for 15 minutes, by which time the diameter and the flow velocity had returned to the baseline levels. Then, sublingal nitroglycerin (300 lag) was administered, and 3 minutes later the last measurements were taken. Data analyses were done as follows. Images were recorded on a super-VHS videocassette recorder (model BR$601M, Victor Corp., Tokyo) and brachial arterial diameters were measured from the tape with ultrasonic calipers by two observers who were blinded as to whether the patient was a control or one who had coronary spastic angina. Measurements were taken from the anterior to the posterior interface between media and adventitia ("m" line) at end diastole, incident with the R wave on a continuously recorded electrocardiogram: 17,19,2o, 22 Diameter at four cardiac cycles was analyzed for each scan, and the measurements were averaged. The diameter measurements for the reactive hyperemia were taken 45 to 90 seconds after cuffdeflation. The response of the vessel to the reactive hyperemia and nitroglycerin was expressed as a percent increase of the baseline value of the diameter. Blood flow was calculated by multiplying the velocity-time integral of the Doppler flow signal by heart rate and the vessel crosssectional area. The increase in brachial blood flow was calculated as a maximum flow recorded in the first 15 seconds after cuffdeflation and was expressed as a percent increase of the baseline value of the flowS, 19,20 In our studies, the interobserver variability for repeated measurement of resting arterial diameter was 0.06 _+ 0.03 mm. The intraobserver variability for repeated measurement of resting arterial diameter was 0.01 _+ 0.09 mm. Furthermore, when this study was performed at the same time on two separate days in 20 controls, the between-occasion within-patient difference for measurement of the percent increase in the arterial diameter during reactive hyperemia was 1.4% _+ 1.2%. Statistics. Data are expressed as mean -+ SD. Comparisons between groups were performed by two-tailed unpaired t test for continuous variables or chi-square test for
-/~/]otoya/~a et aL
265
Diameter change to nitroglycerin
30
p < 0.04 r
•-
20
..
10
o
i
CSA Controls
Fig. 2. Percent increase in brachial arterial diameter after sublingal nitroglycerin administration in 35 patients with coronary spastic angina (CSA) and in 35 controls. categorical variables. Statistical significance was defined as p < 0.05. RESULTS
Baseline values of m e a n blood pressure, h e a r t rate, brachial arterial d i a m e t e r a n d brachial arterial blood flow did not significantly differ b e t w e e n patients with coronary spastic a n g i n a a n d controls (Table II). I n all 70 subjects, including smokers (35 patients with coronary spastic a n g i n a a n d 35 controls), the percent increase in the brachial arterial d i a m e t e r d u r i n g reactive h y p e r e m i a was significantly smaller in patients with c o r o n a r y spastic a n g i n a t h a n in controls (percent increase in the arterial diameter: 5.9% _+ 4.2% vs 9.6% _ 3.4%, p < 0.001) (Fig. 1). However, the percent increase in the brachial arterial blood flow d u r i n g reactive h y p e r e m i a did not significantly differ b e t w e e n patients with c o r o n a r y spastic a n g i n a a n d controls (percent increase in blood flow: 250.7% _+ 89.5% vs 272.6% _+ 78.0%. The percent increase in the d i a m e t e r after sublingal nitroglycerin a d m i n i s t r a t i o n was g r e a t e r in patients with coronary spastic a n g i n a t h a n in controls (percent increase in the arterial diameter: 18.6% _+ 5.1% vs 16.2% _+ 3.9%, p < 0.04) (Fig. 2). I n 38 n o n s m o k i n g subjects (17 p a t i e n t s with coro n a r y spastic a n g i n a and[ 21 controls), the percent increase in the brachial arterial d i a m e t e r d u r i n g reactive h y p e r e m i a was also significantly smaller in
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Motoyama et al.
patients with coronary spastic angina than in controls (percent increase in the arterial diameter: 6.8% _+ 4.7% vs 10.7% _+ 3.2%, p < 0.01). However, the percent increase in the brachial arterial blood flow during reactive hyperemia did not significantly differ between patients with coronary spastic angina and controls (percent increase in the blood flow: 273.7% + 95.6% vs 284.4% _+ 81.5%). The percent increase in the diameter after sublingal nitroglycerin administration was greater in patients with coronary spastic angina than in controls (percent increase in arterial diameter: 19.3% _+ 4.9% vs 16.7% _+ 3.4%, p < 0.05). DISCUSSION
This study showed that percent increase in the brachial arterial diameter in response to reactive hyperemia was smaller in patients with coronary spastic angina than in controls, although there was no significant difference in the percent increase in the brachial arterial blood flow during reactive hyperemia between the patients and the controls. Because the response to nitroglycerin, a direct relaxant of smooth muscle, is preserved, flow-mediated, endothelium-dependent dilatation of the brachial arteries is thought to be impaired in patients with coronary spastic angina compared with controls. Endothelium-dependent vasodilation, which has a crucial role in the regulation of vessel tone, is known to be induced in response to various stimuli. 1°'13, 23, 24 Of these stimuli, blood flow or shear stress is shown to play an important role in the endothelium-dependent regulation of vessel tone at rest, exercise, and cold exposure. 1°-13, 25 We and others have shown that exercise and cold exposure constrict, not dilate, coronary arteries of patients with coronary spastic angina, resulting in the anginal attack. 7, 14 Thus blood flow or shear stress-induced endothelium-dependent vasodilation may possibly be impaired in patients with coronary spastic angina. In this context, this study for the first time demonstrated that flowmediated, endothelium-dependent vasodilation is also impaired in brachial arteries in patients with coronary spastic angina. Therefore the abnormal response of the arteries to blood flow or shear stress may also be present in the systemic arteries in patients with coronary spastic angina. Cigarette smoking, which is a significant risk factor for coronary spastic angina in Japan, is also has been shown to be associated with impairment of endothelium-dependent vasodilation. 19 Therefore we further studied nonsmoking subjects. However, flowdependent dilatation of the brachial arteries was also impaired in patients with coronary spastic angina
American Heart Journal
compared with controls. Therefore genetic factors, in addition to environmental factors such as cigarette smoking, may be concerned with pathogenesis of impaired flow-dependent vasodilation in patients with coronary spastic angina. The precise mechanism for the impairment of endothelium-dependent vasodilation remains undetermined in this study. This study, together with our previous studies, showed that dilator response of the brachial arteries as well as coronary arteries to nitroglycerin was enhanced in patients with coronary spastic angina compared with controls. 14, 15 Increased blood flow has been shown to cause vasodilation by releasing endothelium-dependent relaxing factors, 1° one important component of which has now been identified as nitric oxide. 26 It has recently been shown that nitrovasodilators, including nitroglycerin, cause vasodilation by being converted to nitric oxide. 27 Previous studies showed that removal of the basal nitric oxide-mediated vasodilation in the vascular system leads to supersensitivity to the exogenous nitric oxide. 24, 28 Thus it is quite possible that the systemic arteries, including the brachial arteries and coronary arteries, are hyperresponsive to nitroglycerin because of the deficiency in the endogenous nitric oxide release in these arteries. 8, 9 In fact, we recently found that nitric oxide production and release is deficient in coronary arteries of patients with coronary spastic angina 9 and that a missense mutation in endothelial nitric oxide synthase is frequently associated with patients with coronary spastic angina. 16 These results also strengthen our hypothesis that deficiency in nitric oxide production and release may be generalized in systemic arteries as well as coronary arteries in patients with coronary spastic angina. The increased blood flow induces endothelial production of nitric oxide and other vasodilators such as prostacyclin 29 or hyperpolarizing factor, 3° and decreases of these vasodilators other than nitric oxide may also possibly be involved in the mechanisms of the impaired flow-mediated vasodilation. In conclusion, flow-mediated, endothelium-dependent dilatation of the brachial arteries is impaired in patients with coronary spastic angina, suggesting that the impaired endothelium-dependent regulation of the systemic arterial tone is also present in patients with coronary spastic angina. REFERENCES
1. Hillis LD, Braunwald E. Coronary-artery spasm. N Engl J Med 1978;299:695-702. 2. Conti CR. Coronary artery spasm and myocardial infarction. N Engl J Med 1983;309:238-9. 3. Yasue H, Omote S, Takizawa A, Nagao M. Coronary arterial spasm in
Volume 133, Number 3 American Heart Journal
ischemic heart disease and its pathogenesis. A review. Circ Res 1983;52(suppl I):147-52. 4. Maseri A, Davies G, Hackett D, Kaski JC. Coronary artery spasm and vasoconstriction. The case for a distinction. Circulation 1990;81:198391. 5. Yasue H, Horio Y, Nakamura N, Fujii H, Imote N, Sonoda R, et al. Induction of coronary spasm by acetylcholine in patients with variant angina: possible role of the Parasympathetic nervous system in the pathogenesis of coronary artery spasm. Circulation 1986;74:95563. 6. Okumura K, Yasue H, Matsuyama K, Matsuyama K, Morikami Y, Ogawa H, et al. Effect of ill receptor stimulation on coronary artery diameter in patients with variant angina: comparison with effect of acetylcholine. J Am Call Cardiol 1991;17:338-45. 7. Kaski JC, Crea F, Meran D, Rodriguez L, Araujo L, Chierchia S, Davies G, et al. Local coronary supersensitivity to diverse vasoconstrictive stimuli in patients with variant angina. Circulation 1986;74:125565. 8. Yasue H. Pathogenesis and clinical features of coronary spasm. J Jpn Sac Intern Med 1995;84:1407-15. 9. Kugiyama K, Yasue H, Okumura K, Ogawa H, Fujimoto K, Nakao K, Yoshimura M, et al. Nitric oxide activity is deficient in spasm arteries of patients With coronary spastic angina. Circulation 1996;94:266-72. 10. Rubanyi GM, Romero JC, Vanhoutte PM. Flow-induced release ofendothelium-derived relaxing factor. Am J Physiol 1986;250:Hl145-9. 11. Vallance P, Collier J. Moncada S. Effects of endothelium-derived nitric oxide on peripheral arteriolar tone in man. Lancet 1989;2:997-1000. 12. Nabel EG, Selwyn AP, Ganz P. Large coronary arteries in human are responsive to changing blood flow: an endothelium-dependent mechanism that fails in patients with atherosclerosis. J Am Call Cardiol 1990;16:349-56. 13. Gilligan DM, Panza JA, Kilcoyne CM, Waclawiw MA, Casino PR, Quyyumi AA. Contribution of endothelium-derived nitric oxide to exercise-induced vasodilation. Circulation 1994;90:2853-8. 14. Yasue H, Omote S, Takizawa A, Nagao M, Miwa K, Tanaka S. Circadian variation of exercise capacity in patients with Prinzmetal's variant angina: role of exercise-induced coronary arterial spasm. Circulation 1979;59:938-48. 15., Okumura K, Yasue H, Matsuyama K, Ogawa H, Kugiyama K, Ishizaka H, et al. Diffuse disorder of coronary artery vasomotility in patients with coronary spastic angina: hyperreactivity to the constrictor effects of acetylcholine and the dilator effects of nitroglycerin. J Am Call Cardial 1996;27:45-52. 16. Yasue H, Yoshimura M, Sugiyama S, Sumida H, Okumura K, Ogawa H, et al. Association of a point mutation of the endothelial cell nitric
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oxide synthase (eNOS) gene with coronary spasm [abstract]. Circulation 1995;92(suppl I):369. 17. Celermajer DS, Sorensen KE, Bull C, Robinson J, Deanfield JE. Endothelinm-dependent dilation in the systemic arteries of asymptomatic subjects relates to coronary risk factors and their interaction. J Am Call Cardiol 1994;24:1468-74. 18. Sugiishi M, Takatsu F. Cigarette smoking is a major risk factor for coronary spasm. Circulation 1993;87:76-9. 19~ Celermajer DS, Sorensen KE, Georgakopoulos D. Bull C, Thomas O, Robinson J, et al. Cigarette smoking is associated with dose-related and potentially reversible impairment of endothelium-dependent dilation in healthy young adults. Circulation 1993;88:2149-55. 20. Celermajer DS, Sorensen KE, Gaoch VM, Spiegelhalter DJ, Miller OI, Sullivan ID, et al. Non-invasive detection of endothelial dysfunction in children and adults at risk of atherosclerosis. Lancet 1992;340:1111-5. 21. Anderson TJ, Uehata A, Gerhard MD, Meredith IT, Knab S, Delagrange D, et al. Close relation of endothelial function in human corenary and peripheral circulations. J Am Call Cardiol 1995;26:1235-41. 22. Wendelhag I, Gustavsson T, Suurkula M, Berglund G, Wikstrand U. Ultrasound measurement of wall thickness in the carotid artery: fundamental principles and description of computerized analyzing system. Clin Physiol 1991;11:565-77. 23. Cocks TM, Angus JA. Endothe!ium-dependent relaxation of coronary arteries by noradrenaline and serotonin. Nature 1983;305:627-30. 24. Bassenge E. Coronary vasomotor responses: role of endothelinm and nitrovasodilators. Cardiovasc Drug Ther 1994;8:600-12. 25. Nabel EG, Ganz P, Gordon JB, Wayne Alexander R, Selwyn AP. Dilation of normal and constriction of atherosclerotic coronary arteries caused by the cold pressor test. Circulation 1988;77:43-52. 26. Palmer RMJ, Ferrige AG, Moncada S. Nitric oxide release accounts for the biological activity of endothelinm-derived relaxing factor. Nature 1987;327:524-6. 27. Feelisch M. The biochemical pathway of nitric oxide formation from nitrovasodilators: appropriate choice of exogenous NO donors and aspects of preparation and handling of aqueous NO solutions. J Cardiovasc Pharmacol 1991;17(suppl 3):$25-33. 28. Moncada S, Ress DD, Schulz R, Palmer RMJ. Development and mechanism of a specific supersensitivity to nitrovasodilaters after inhibition of vascular nitric oxide synthesis in viva. Proc Natl Acad Sci USA 1991;88:2166-70. 29. Moncada S, Vane JR. Pharmacology and endogenous roles of prostagiandin endoperoxides, thromboxane A2 and prostacyclin. Pharmacol Rev 1979;30:293-331. 30. Feletou M, Vanhoutte PM. Endothelinm-dependent hyperpotarization of canine coronary smooth muscle. Br J Pharmacol 1988;93:515-24.
March 1997 Volume 133, Number 3
CLINICAL INVESTIGATIONS
Acute Ischemic Heart Disease
Flow-mediated, endothelium-dependent dilatation of the brachial arteries is impaired in patients with coronary spastic angina Takeshi Motoyama, MD, Hiroaki Kawano, MD, Kiyotaka Kugiyama, MD, Ken Okumura, MD, Masamichi Ohgushi, MD, Michihiro Yoshimura, MD, Osamu Hirashima, MD, and Hirofumi Yasue, MD
Kumamoto, Japan Coronary spasm is induced by acetylcholine, serotonin, ergonovine, or histamine, all of which cause vasodilation when the endothelium is intact, and is promptly relieved by nitroglycerin, which vasodilates through the direct action on smooth muscle. Endothelial dysfunction is therefore possibly involved in the pathogenesis of coronary artery spasm. The aim of this study was to determine whether endotheliurn-dependent vasodilation is impaired in the peripheral arteries of patients with coronary spastic angina. Flow-dependent vasodilaUon of the brachial arteries during reactive hyperemia after the transient arterial occlusion was examined by using the high-resolution ultrasound technique in 35 patients with coronary spastic angina and 35 controls. Flowdependent vasodilation of the brachial arteries was impaired in patients with coronary spastic angina compared with controls (5.9% ± 4.2% vs 9.6% ± 3.4%, p < 0.001) although the percent increase in blood flow during reactive hyperemia was not different between the two groups. The dilator response to nitroglycerin was preserved in patients with coronary spastic angina compared with controls (18.6% ± 5.1% vs 16.2% ± 3.9%, p < 0.04). The results indicate that endothelium-dependent vasodilation of the brachJal arteries is impaired in patients with coronary spastic angina. Thus endothelial vasomotor dysregulation may also be present in the systemic arteries as well as coronary arteries in patients with coronary spastic angina. (Am Heart J 1997;133:263-7.) From the Division of Cardiology, Kumamoto University School of Mediciae. Supported in part by grants-in-aid for Scientific Research on Priority Area (03268107), B03454257, and C3670460 from t h e Ministry of Education, Science, and Culture in Japan, and the Smoking Research Foundation, Tokyo, Japan. Received for publication May 14, 1996; accepted Aug. 8, 1996. Reprint requests: Hirofumi Yasue, MD, Division of Cardiology, Kumamoto University School of Medicine, Honjo 1-1-1, Kumamoto City, Japan 860. Copyright © 1997 by Mosby-Year Book, Inc. 0002-8703/97/$5.00 + 0 4/1/78084
Coronary spasm plays an important role in the pathogenesis of variant angina and ischemic heart disease in general, including other forms of angina pectoris, acute myocardial infarction, and sudden death. TM However, the precise mechanism by which coronary spasm occurs remains unknown. Coronary spasm is induced by acetylcholine, serotonin, ergonovine, or histamine, all of which cause vasodilation when the endothelium is intact, and is promptly relieved by nitroglycerin, which vasodilates through the direct action on smooth muscle. 5-7 The impairment of endothelium-dependent vasodilation is therefore possibly involved in the pathogenesis of coronary artery spasm, s, 9 Flow-dependent vasodilation is known to have an important role in the regulation of the arterial tone at rest and exercise. 1°-13 We have shown that spasm arteries show increased basal tone and do not dilate, but constrict at exercise, and that the increased arterial tone is an important contributor to the anginal attack in patients with coronary spastic angina. 14, 15 Flow-mediated, endothelium-dependent arterial relaxation may therefore conceivably be impaired in patients with coronary spastic angina. As a matter of fact, we demonstrated that a diffuse, nonlocalized disorder in vasom0tility , including endothelium-dependent vasodilation, is involved in the pathogenesis of coronary spastic angina. 15 Furthermore, we have recently found that a missense mutation in endothelial nitric oxide synthase is frequently associated with patients with coronary spastic angina. 16 Therefore 263
March 1997
264
Motoyama et al.
American Heart Journal
20
400 p < 0.001 i
P = NS
¢
,= 300
i
.= 1C
200 100
0
CSA Controls
0
CSA Controls
Fig. 1. Percent increase in brachial arterial diameter during reactive hyperemia (left) and percent increase in brachial blood flow observed immediately after cuff deflation (peak reactive hyperemia) ( r i g h t ) in 35 patients with coronary spastic angina ( C S A ) and 35 controls.
Table L Characteristics of study patients CSA (n = 35)
Age (yr) Men/women No. of smokers (%) Total cholesterol (mg/dl) HDL cholesterol (mg/dl)
Controls (n = 35)
61.9 -+ 13.9 61.1 -+ 11.9 16/19 16/19 18 (51.4) 14 (40.0) 180.5 _+28.0 182.1_+26.8 52.9 +_14.1
51.5 _+12.6
Table ]L Baseline values of mean blood pressure, heart rate, brachial diameter, and brachial blood flow p Values
NS NS NS NS NS
Values are expressed as mean -+ SD. CSA, Coronary spastic angina; HDL, high-density lipoprotein; NS, not significant.
the d i s t u r b a n c e of v a s o m o t o r regulation m a y exist in the systemic arteries as well as coronary arteries in p a t i e n t s w i t h c o r o n a r y spastic angina. This s t u d y was designed to examine by u l t r a s o u n d technique w h e t h e r flow-dependent vasodilation during reactive h y p e r e m i a is i m p a i r e d in the brachial arteries in patients with coronary spastic a n g i n a as c o m p a r e d with controls.
METHODS Patients. The study included 35 patients with coronary spastic angina (mean age 61.9 years, range 33 to 77 years, 16 men) in whom episodes of spontaneous angina occurred at rest. All the patients with coronary spastic angina had angiographically normal coronary arteries and showed angiographically documented coronary spasm associated with ischemic ST-segment changes after the intracoronary injection of acetylcho]ine, as previously reported. 5 The study also included 35 control subjects (mean age 61.1 years, range 32 to 76 years, 16 men). These control subjects were selected to match the risk factors for atherosclerosis to those in patients with coronary spastic angina (Table I). The control subjects underwent diagnostic cardiac catheterization for evaluation of chest pain. They had anglo-
CSA (n = 35)
Controls (n = 35)
Mean blood pressure 87.5 -- 9.3 87.4 _+9.5 (ram Hg) Heart rate (beats/min) 60.1 _+9.4 63.7 _+9.0 Diameter (ram) 3.77 _+0.55 3.87 _+0.51 Blood flow (m]/min) 188.6 _+69.5 196.2 + 67.9
p Values
NS NS NS NS
Values are expressed as m e a n -+ SD. CSA, Coronary spastic angina; NS, not significant.
graphically normal coronary arteries and did not show coronary spasm after the intracoronary injection of acetylcholine. All 70 subjects were normotensive (blood pressure <160/90 mm Hg), did not have diabetes, and had plasma total cholesterol <240 mg/dl. These risk factors for atherosclerosis have been shown to be associated with impairment of endothelium-dependent vasodilation. 17 Cigarette smoking, which is a significant risk factor for coronary spastic angina in Japan, is also has been shown to be associated with impairment of endothelium-dependent vasodilation. 19 Therefore we studied all 70 subjects, including smokers, at first. We further studied 38 subjects, excluding smokers from the original 70 subjects. No patients had previous myocardial infarction, congestive heart failure, or other serious disease. Written informed consent was obtained from all patients before the study. The study was in agreement with the guidelines approved by the ethics committee at our institution. Study design. We obtained scans in each brachial artery with high-resolution ultrasound from all 70 study subjects. All medications except sublingal nitroglycerin were withdrawn at least 3 days before the study. No study patients had taken nitroglycerin within 6 hours before the study. The study was performed at 6 AMwhile the patients were fasting because coronary spasm often occurs in the early morning. 14 The vasodilator responses in the brachial arteries were measured by the ultrasound technique pre-
Volume 133, Number 3 American Heart Journal
viously validated by Celermajer et al. 17,19,20 The diameter of the brachial artery was measured from B-mode ultrasound images with a 7.5 MHz linear array transducer (model SSH-160A ultrasound system, Toshiba Corp., Tokyo). 21 The flow velocity of the brachia] artery was measured with a pulsed Doppler signal at a 70-degree angle to the vessel, with the range gate (1.5 mm) in the center of the artery. The brachial artery was longitudinally scanned in the antecubital fossa. Gain setting was optimized at the beginning of the study and was kept constant throughout the recording period. When a satisfactory transducer position was found, the surface of the skin was marked and the arm remained in the same position throughout the study. The subjects lay quietly for 10 minutes before the scan. After baseline measurements of the diameter and the flow velocity in the brachial artery, a blood pressure cuff placed around the forearm was inflated with a pressure of 250 to 300 mm Hg. After 4.5 minutes, the cuffwas released. Diameter and flow velocity were continuously measured during and after cuff deflation. Thereafter the subjects lay quietly for 15 minutes, by which time the diameter and the flow velocity had returned to the baseline levels. Then, sublingal nitroglycerin (300 lag) was administered, and 3 minutes later the last measurements were taken. Data analyses were done as follows. Images were recorded on a super-VHS videocassette recorder (model BR$601M, Victor Corp., Tokyo) and brachial arterial diameters were measured from the tape with ultrasonic calipers by two observers who were blinded as to whether the patient was a control or one who had coronary spastic angina. Measurements were taken from the anterior to the posterior interface between media and adventitia ("m" line) at end diastole, incident with the R wave on a continuously recorded electrocardiogram: 17,19,2o, 22 Diameter at four cardiac cycles was analyzed for each scan, and the measurements were averaged. The diameter measurements for the reactive hyperemia were taken 45 to 90 seconds after cuffdeflation. The response of the vessel to the reactive hyperemia and nitroglycerin was expressed as a percent increase of the baseline value of the diameter. Blood flow was calculated by multiplying the velocity-time integral of the Doppler flow signal by heart rate and the vessel crosssectional area. The increase in brachial blood flow was calculated as a maximum flow recorded in the first 15 seconds after cuffdeflation and was expressed as a percent increase of the baseline value of the flowS, 19,20 In our studies, the interobserver variability for repeated measurement of resting arterial diameter was 0.06 _+ 0.03 mm. The intraobserver variability for repeated measurement of resting arterial diameter was 0.01 _+ 0.09 mm. Furthermore, when this study was performed at the same time on two separate days in 20 controls, the between-occasion within-patient difference for measurement of the percent increase in the arterial diameter during reactive hyperemia was 1.4% _+ 1.2%. Statistics. Data are expressed as mean -+ SD. Comparisons between groups were performed by two-tailed unpaired t test for continuous variables or chi-square test for
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Diameter change to nitroglycerin
30
p < 0.04 r
•-
20
..
10
o
i
CSA Controls
Fig. 2. Percent increase in brachial arterial diameter after sublingal nitroglycerin administration in 35 patients with coronary spastic angina (CSA) and in 35 controls. categorical variables. Statistical significance was defined as p < 0.05. RESULTS
Baseline values of m e a n blood pressure, h e a r t rate, brachial arterial d i a m e t e r a n d brachial arterial blood flow did not significantly differ b e t w e e n patients with coronary spastic a n g i n a a n d controls (Table II). I n all 70 subjects, including smokers (35 patients with coronary spastic a n g i n a a n d 35 controls), the percent increase in the brachial arterial d i a m e t e r d u r i n g reactive h y p e r e m i a was significantly smaller in patients with c o r o n a r y spastic a n g i n a t h a n in controls (percent increase in the arterial diameter: 5.9% _+ 4.2% vs 9.6% _ 3.4%, p < 0.001) (Fig. 1). However, the percent increase in the brachial arterial blood flow d u r i n g reactive h y p e r e m i a did not significantly differ b e t w e e n patients with c o r o n a r y spastic a n g i n a a n d controls (percent increase in blood flow: 250.7% _+ 89.5% vs 272.6% _+ 78.0%. The percent increase in the d i a m e t e r after sublingal nitroglycerin a d m i n i s t r a t i o n was g r e a t e r in patients with coronary spastic a n g i n a t h a n in controls (percent increase in the arterial diameter: 18.6% _+ 5.1% vs 16.2% _+ 3.9%, p < 0.04) (Fig. 2). I n 38 n o n s m o k i n g subjects (17 p a t i e n t s with coro n a r y spastic a n g i n a and[ 21 controls), the percent increase in the brachial arterial d i a m e t e r d u r i n g reactive h y p e r e m i a was also significantly smaller in
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patients with coronary spastic angina than in controls (percent increase in the arterial diameter: 6.8% _+ 4.7% vs 10.7% _+ 3.2%, p < 0.01). However, the percent increase in the brachial arterial blood flow during reactive hyperemia did not significantly differ between patients with coronary spastic angina and controls (percent increase in the blood flow: 273.7% + 95.6% vs 284.4% _+ 81.5%). The percent increase in the diameter after sublingal nitroglycerin administration was greater in patients with coronary spastic angina than in controls (percent increase in arterial diameter: 19.3% _+ 4.9% vs 16.7% _+ 3.4%, p < 0.05). DISCUSSION
This study showed that percent increase in the brachial arterial diameter in response to reactive hyperemia was smaller in patients with coronary spastic angina than in controls, although there was no significant difference in the percent increase in the brachial arterial blood flow during reactive hyperemia between the patients and the controls. Because the response to nitroglycerin, a direct relaxant of smooth muscle, is preserved, flow-mediated, endothelium-dependent dilatation of the brachial arteries is thought to be impaired in patients with coronary spastic angina compared with controls. Endothelium-dependent vasodilation, which has a crucial role in the regulation of vessel tone, is known to be induced in response to various stimuli. 1°'13, 23, 24 Of these stimuli, blood flow or shear stress is shown to play an important role in the endothelium-dependent regulation of vessel tone at rest, exercise, and cold exposure. 1°-13, 25 We and others have shown that exercise and cold exposure constrict, not dilate, coronary arteries of patients with coronary spastic angina, resulting in the anginal attack. 7, 14 Thus blood flow or shear stress-induced endothelium-dependent vasodilation may possibly be impaired in patients with coronary spastic angina. In this context, this study for the first time demonstrated that flowmediated, endothelium-dependent vasodilation is also impaired in brachial arteries in patients with coronary spastic angina. Therefore the abnormal response of the arteries to blood flow or shear stress may also be present in the systemic arteries in patients with coronary spastic angina. Cigarette smoking, which is a significant risk factor for coronary spastic angina in Japan, is also has been shown to be associated with impairment of endothelium-dependent vasodilation. 19 Therefore we further studied nonsmoking subjects. However, flowdependent dilatation of the brachial arteries was also impaired in patients with coronary spastic angina
American Heart Journal
compared with controls. Therefore genetic factors, in addition to environmental factors such as cigarette smoking, may be concerned with pathogenesis of impaired flow-dependent vasodilation in patients with coronary spastic angina. The precise mechanism for the impairment of endothelium-dependent vasodilation remains undetermined in this study. This study, together with our previous studies, showed that dilator response of the brachial arteries as well as coronary arteries to nitroglycerin was enhanced in patients with coronary spastic angina compared with controls. 14, 15 Increased blood flow has been shown to cause vasodilation by releasing endothelium-dependent relaxing factors, 1° one important component of which has now been identified as nitric oxide. 26 It has recently been shown that nitrovasodilators, including nitroglycerin, cause vasodilation by being converted to nitric oxide. 27 Previous studies showed that removal of the basal nitric oxide-mediated vasodilation in the vascular system leads to supersensitivity to the exogenous nitric oxide. 24, 28 Thus it is quite possible that the systemic arteries, including the brachial arteries and coronary arteries, are hyperresponsive to nitroglycerin because of the deficiency in the endogenous nitric oxide release in these arteries. 8, 9 In fact, we recently found that nitric oxide production and release is deficient in coronary arteries of patients with coronary spastic angina 9 and that a missense mutation in endothelial nitric oxide synthase is frequently associated with patients with coronary spastic angina. 16 These results also strengthen our hypothesis that deficiency in nitric oxide production and release may be generalized in systemic arteries as well as coronary arteries in patients with coronary spastic angina. The increased blood flow induces endothelial production of nitric oxide and other vasodilators such as prostacyclin 29 or hyperpolarizing factor, 3° and decreases of these vasodilators other than nitric oxide may also possibly be involved in the mechanisms of the impaired flow-mediated vasodilation. In conclusion, flow-mediated, endothelium-dependent dilatation of the brachial arteries is impaired in patients with coronary spastic angina, suggesting that the impaired endothelium-dependent regulation of the systemic arterial tone is also present in patients with coronary spastic angina. REFERENCES
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ischemic heart disease and its pathogenesis. A review. Circ Res 1983;52(suppl I):147-52. 4. Maseri A, Davies G, Hackett D, Kaski JC. Coronary artery spasm and vasoconstriction. The case for a distinction. Circulation 1990;81:198391. 5. Yasue H, Horio Y, Nakamura N, Fujii H, Imote N, Sonoda R, et al. Induction of coronary spasm by acetylcholine in patients with variant angina: possible role of the Parasympathetic nervous system in the pathogenesis of coronary artery spasm. Circulation 1986;74:95563. 6. Okumura K, Yasue H, Matsuyama K, Matsuyama K, Morikami Y, Ogawa H, et al. Effect of ill receptor stimulation on coronary artery diameter in patients with variant angina: comparison with effect of acetylcholine. J Am Call Cardiol 1991;17:338-45. 7. Kaski JC, Crea F, Meran D, Rodriguez L, Araujo L, Chierchia S, Davies G, et al. Local coronary supersensitivity to diverse vasoconstrictive stimuli in patients with variant angina. Circulation 1986;74:125565. 8. Yasue H. Pathogenesis and clinical features of coronary spasm. J Jpn Sac Intern Med 1995;84:1407-15. 9. Kugiyama K, Yasue H, Okumura K, Ogawa H, Fujimoto K, Nakao K, Yoshimura M, et al. Nitric oxide activity is deficient in spasm arteries of patients With coronary spastic angina. Circulation 1996;94:266-72. 10. Rubanyi GM, Romero JC, Vanhoutte PM. Flow-induced release ofendothelium-derived relaxing factor. Am J Physiol 1986;250:Hl145-9. 11. Vallance P, Collier J. Moncada S. Effects of endothelium-derived nitric oxide on peripheral arteriolar tone in man. Lancet 1989;2:997-1000. 12. Nabel EG, Selwyn AP, Ganz P. Large coronary arteries in human are responsive to changing blood flow: an endothelium-dependent mechanism that fails in patients with atherosclerosis. J Am Call Cardiol 1990;16:349-56. 13. Gilligan DM, Panza JA, Kilcoyne CM, Waclawiw MA, Casino PR, Quyyumi AA. Contribution of endothelium-derived nitric oxide to exercise-induced vasodilation. Circulation 1994;90:2853-8. 14. Yasue H, Omote S, Takizawa A, Nagao M, Miwa K, Tanaka S. Circadian variation of exercise capacity in patients with Prinzmetal's variant angina: role of exercise-induced coronary arterial spasm. Circulation 1979;59:938-48. 15., Okumura K, Yasue H, Matsuyama K, Ogawa H, Kugiyama K, Ishizaka H, et al. Diffuse disorder of coronary artery vasomotility in patients with coronary spastic angina: hyperreactivity to the constrictor effects of acetylcholine and the dilator effects of nitroglycerin. J Am Call Cardial 1996;27:45-52. 16. Yasue H, Yoshimura M, Sugiyama S, Sumida H, Okumura K, Ogawa H, et al. Association of a point mutation of the endothelial cell nitric
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