Nitric oxide activity is deficient in spasm arteries of patients with coronary spastic angina

Effect of cilostazol on vasomotor reactivity in patients with vasospastic angina pectoris

We examined the effects of cilostazol on impaired coronary arterial responses in patients with vasospastic angina (VSA). Thirty patients who were diagnosed with VSA based on an acetylcholine provocation test and 10 subjects with normal coronary arteries were enrolled. The patients were divided into the following 3 groups: no antiplatelet agent treatment group, aspirin treatment, or cilostazol treatment groups. Coronary flow reserve (CFR), coronary flow volume at maximum hyperemia, and epicardial coronary artery diameter after administration of N(G)-monomethyl-L-arginine (L-NMMA) were examined using a Doppler flow wire before and 6 months after the start of this study. CFR, coronary flow volume at maximum hyperemia, and diameter changes by L-NMMA were significantly increased in the cilostazol treatment group compared with the other 2 groups. In conclusion, cilostazol increased CFR and flow-dependent coronary dilation; these changes were attributable to nitric oxide. Cilostazol may improve coronary vascular endothelial dysfunction and coronary hemodynamics in patients with VSA.

The Glu298Asp polymorphism in the endothelial nitric oxide synthase gene is strongly associated with coronary spasm

BACKGROUND

Coronary spasm seems to be associated with coronary nitric oxide deficiency.

OBJECTIVES

We investigated whether the Glu298Asp polymorphism in the endothelial nitric oxide synthase (eNOS) gene is a definite risk factor for coronary spasm and whether diffuse spasm involving normal-looking coronary artery correlates significantly with the Glu298Asp polymorphism, in contrast with focal spasm superimposed on an atherosclerotic plaque.

METHODS

A polymerase chain reaction followed by restriction fragment length polymorphism analysis was performed in 118 control participants and in 102 patients with variant angina and a similar degree of atherosclerotic burden. Patients with coronary spasm were divided into diffuse spasm and focal spasm subgroups according to morphological criteria.

RESULTS

There was a significantly higher incidence of the Glu298Asp polymorphism in the coronary spasm group than in the control group (21.5% compared with 8.5%, P=0.006). Multiple logistic regression analysis using risk factors and the Glu298Asp polymorphism showed that the most important predictive factor for coronary spasm was the Glu298Asp polymorphism (odds ratio 2.83, 95% confidence interval 1.25-6.41, P=0.009). The diffuse spasm subgroup had a significantly higher frequency of the Glu298Asp polymorphism than the control group (25.9% compared with 8.5%, P=0.002). However, the focal spasm subgroup did not differ from the control group in the frequency of Glu298Asp polymorphism.

CONCLUSION

The Glu298Asp polymorphism in the eNOS gene is a definite risk factor for coronary spasm, especially for diffuse coronary spasm. This result supports the notion that diffuse coronary spasm is significantly associated with endothelial dysfunction, in contrast to focal spasm.

Self-vasodilating ability at the spastic site of patients with vasospastic angina: estimation by acetylcholine delayed phase

Deficient nitric oxide (NO) release is thought to be the principal mechanism of coronary spasm, however, the precise mechanisms are unknown. Although acetylcholine (ACh) is used for provocation of coronary spasm, ACh is also used for the augmentation of blood flow and flow-mediated vasodilation is induced. We estimated the self-vasodilating ability (endothelial function) at the spastic site of coronary arteries in patients with vasospastic angina (VSA) during the provocation test of coronary spasm by ACh. This study included 93 patients with VSA and 77 patients with atypical chest pain (ACP). Intracoronary injection of ACh (20, 50, and 100 microg) was performed over 30 seconds and the coronary artery diameter of the spastic site was measured 3 to 4 minutes after ACh injection (delayed phase). The ability of dilation (AOD) was calculated as: ([diameter of delayed phase-baseline diameter]/[diameter after isosorbide dinitrate-baseline diameter]) x 100 (%). No significant difference was noted between the AOD in patients with ACP and VSA (28 +/- 36 vs 15 +/- 60%, respectively). The AOD values of 49% of patients with VSA were greater than the mean value of AOD of patients with ACP. At least almost half of the patients with VSA may have preserved self-vasodilating ability at the spastic site, and an abnormality other than endothelial dysfunction is involved in the mechanism of coronary spasm in these patients.

Significance of asymmetric dimethylarginine (ADMA) concentrations during coronary circulation in patients with vasospastic angina

The basal activity of nitric oxide (NO) is reduced in spastic arteries of patients with vasospastic angina (VSA). Elevated concentrations of ADMA are associated with reduced NO production and impaired endothelium-dependent vasodilatation. The aim of this study was to elucidate the role of ADMA and its relationship to NO end-products (NOx; nitrate + nitrite) during coronary circulation in patients with VSA. The plasma ADMA and NOx concentrations during coronary circulation were evaluated in 16 VSA and 16 control patients. Blood samples were obtained from the coronary sinus (V) and the ostium of the left coronary artery (A), and the (V-A) differences of ADMA and NOx were determined. The coronary sinus plasma ADMA concentration in patients with VSA was higher than that in the control. The coronary sinus - arterial (V-A) difference of NOx was negative in the VSA group and approximately zero in the control group (VSA group =-1.4 micromol/L, control group =-0.1 micromol/L, p=0.0005). Furthermore, in the VSA patients, there was a negative correlation between the (V-A) difference of NOx and the basal coronary artery tone at the site of spasm (r=-0.60, p=0.015). A significant negative correlation between the (V-A) differences of NOx and ADMA was observed in patients with VSA (r=-0.52, p<0.05), but not in those of the control. Higher ADMA concentrations might cause the reduced formation of NO that underlies the pathophysiology of coronary vasospasm.

Acetylcholine-induced coronary spasm with a history of Kawasaki disease: case report

A 21-year-old woman without any known coronary risk factors was found at coronary catheterization to have normal coronary angiograms, but demonstrated acethylcholine (ACh)-induced coronary spasm. She had a history of Kawasaki disease (KD) at 19 months of age and, although coronary angiography was not performed at that time, no coronary aneurysms were detected by echocardiography. To the best of our knowledge, this is the first case report of ACh-induced coronary spasm associated with normal coronary angiograms in a young person with a history of KD. The findings suggest that subclinical, persistent coronary endothelial dysfunction may exist in this patient; furthermore, the dysfunction appears diffuse and might be unrelated to coronary aneurysm formation. The long-term significance of coronary endothelial dysfunction in patients with KD, as suspected by coronary spasm, remains unknown but may be an important risk factor for future atherosclerosis.

Low density lipoprotein particles are small in patients with coronary vasospasm

Increased lipid oxidative stress has been recently implicated in the pathogenesis of coronary artery spasm. Small, dense LDL with high susceptibility to oxidation may be linked to the genesis of coronary vasospasm. The relative migratory distance of the predominant densitometric peak of LDL from that of VLDL to that of HDL in a 3% polyacrylamide gel electrophoresis was determined as a measure of LDL particle size in 49 patients with coronary spastic angina (CSA), in 56 patients with stable effort angina and a significant coronary artery stenosis (SEA) and also in 40 control subjects without coronary artery disease (Control). The incidence of detection of small, dense LDL (particle diameter <25.5 nm) or a relative migratory distance above 0.36 was significantly higher in CSA (57%) and also in SEA (39%) than in Control (20%). In SEA, a significantly higher serum level of triglyceride was noted in the subgroup with the small, dense LDL as compared with the subgroup without. In contrast, in CSA, the serum level of triglyceride was not significantly different between the subgroups with and without the small, dense LDL, although significantly lower serum levels of both HDL-cholesterol and alpha-tocopherol were noted in the former. In 16 patients of CSA, the detection of the small, dense LDL was significantly decreased after a >6-month angina-free period (69-->31%). We conclude that patients with coronary spastic angina had smaller LDL particles, associated not with hypertriglyceridemia but low serum levels of both HDL-cholesterol and vitamin E. Dyslipidemia with small, dense LDL may be related to the genesis of coronary vasospasm.

Plasminogen activator inhibitor contributes to the coronary wall thickening in patients with angiographically normal coronary

INTRODUCTION

Angiographically normal coronary arteries have concealed intimal thickening that importantly contribute to coronary arterial disease activity. Increased plasma levels of plasminogen activator inhibitor (PAI) are associated with myocardial infarction and atherosclerosis. However, it remains unclear whether the PAI contributes to vascular wall thickening detected by intravascular ultrasound (IVUS) in normal coronary angiogram. The aim of this study was to evaluate if the PAI activity contributes to the extent of atherosclerotic changes in angiographically normal coronary arteries using IVUS technique.

MATERIALS AND METHODS

We studied 33 consecutive patients with normal coronary angiograms. These patients were divided into a high level of plasma PAI activity group (H-PAI; n=12) and a normal range of PAI activity group (N-PAI; n=21), according to the plasma PAI activity levels.

RESULTS

The average of "percent intima+media area (%I+M area)" and "maximal intima+media (I+M) thickness" were significantly greater in the H-PAI group as compared with those in the N-PAI group (p<0.05). Minimal lumen diameter and lumen area were comparable between these groups. The plasma PAI activity level was the independent predictor of increase in maximal I+M thickness, in multiple regression analysis with the traditional risk factors as covariates.

CONCLUSIONS

Thickened intima+media of angiographically normal coronary arteries were associated with high plasma level of PAI activity, independently of other traditional risk factors. PAI may contribute to the pathogenesis of coronary intimal thickening that might increase coronary arterial tone.

Plaque Morphology at Coronary Sites With Focal Spasm in Variant Angina-Study Using Intravascular Ultrasound-

In the present study, the intravascular ultrasound (IVUS) morphologic appearance of coronary atherosclerotic plaque associated with focal spasm was prospectively studied in 45 patients with or without focal coronary spasm provoked by ergonovine or acetylcholine. The percent plaque area and plaque arc were determined from the IVUS images at the sites of spasm. Calcified lesion was defined as the presence of high-intensity echo with acoustic shadowing. Twenty-three patients had focal coronary spasm defined as angiographic narrowing >75% and IVUS demonstrated atherosclerotic plaque in these 23 sites. In the 22 patients without focal spasm, IVUS demonstrated 18 atherosclerotic lesions in 17 patients and the remaining 5 patients did not have significant lesions. There was no difference in the percent plaque area and plaque arc between plaque lesions with (47+/-10%, 298+/-71 degrees ) and without (39+/-15%, 249+/-83 degrees ) coronary spasm. Interestingly, calcified lesion was less frequently present at the sites with than at those without spasm (p<0.05). These results indicate that the presence of plaque without calcification is likely to be related to the occurrence of focal vasospasm, although the severity and distribution of the disease did not differ between each patient group.

Effect of alcohol consumption on endothelial function in men with coronary artery disease

An inverse relationship between moderate alcohol consumption and coronary artery disease (CAD) has been observed in several epidemiologic studies. Whether improvement of endothelial function is involved in this beneficial effect is unknown. We investigated endothelial function of the brachial artery in 108 men with CAD, 54 of whom consumed alcohol on at least 1 day per week. Brachial artery diameter responses to hyperemic flow (FMD) and to administration of nitroglycerin (NTG) spray were measured using high- resolution ultrasonography. Coronary risk factors and hyperuricemia were present more frequently among drinkers, who also had higher concentrations of triglyceride and apolipoproteins C2, C3, and E. FMD was greater in drinkers (P<0.0001), while NTG-induced dilation was not. Multiple regression analysis showed alcohol consumption to be one of the factors favorably influencing FMD. These findings suggest that alcohol consumption may improve endothelial function in men with CAD.

Nitric oxide and cardioprotection during ischemia-reperfusion

Coronary artery reperfusion is widely used to restore blood flow in acute myocardial infarction and limit its progression. However, reperfusion of ischemic myocardium results in reperfusion injury and persistent ventricular dysfunction even when achieved after brief periods of ischemia. Normally, small amounts of nitric oxide (NO) generated by endothelial NO synthase (eNOS) regulates vascular tone. Ischemia-reperfusion triggers the release of oxygen free radicals (OFRs) and a cascade involving endothelial dysfunction, decreased eNOS and NO, neutrophil activation, increased cytokines and more OFRs, increased inducible NO synthase (iNOS) and marked increase in NO, excess peroxynitrite formation, and myocardial injury. Low doses of NO appear to be beneficial and high doses harmful in ischemia-reperfusion. eNOS knock-out mice confirm that eNOS-derived NO is cardioprotective in ischemia-reperfusion. iNOS overexpression increases peroxynitrite but did not cause severe dysfunction. Increased angiotensin II (AngII) after ischemia-reperfusion inactivates NO, forms peroxynitrite and produces cardiotoxic effects. Beneficial effects of angiotensin-converting-enzyme inhibition and AngII type 1 (AT(1)) receptor blockade after ischemia-reperfusion are partly mediated through AngII type 2 (AT(2)) receptor stimulation, increased bradykinin and NO. Interventions that enhance NO availability by increasing eNOS might be beneficial after ischemia-reperfusion.

The disappearing coronary stenosis: reemphasizing the importance of excluding coronary vasospasm before coronary intervention

We describe a case of resting angina with multiple angiographic stenoses that were highly suitable for stenting. These classic lesions resolved after intracoronary nitroglycerin while positioning a stent. This case reemphasizes the need to exclude vasospasm prior to any interventional coronary procedure.

[Coronary Spasm after Administration of Propranolol during Dobutamine Stress Echocardiography]

Dobutamine stress echocardiography, a highly useful and safe challenge test for myocardial ischemia, is being used increasingly. We report the case of a 37-year-old man with rest angina, repolarization abnormalities in precordial leads and normal coronary arteries who was referred for dobutamine-atropine stress echocardiography, which was negative for ischemia. However, after testing, upon injection of propranolol, the patient suffered chest pain associated with ST elevation and severe regional systolic abnormalities. After intravenous nitroglycerin administration, chest pain and electrocardiographic abnormalities disappeared quickly, and systolic motion became normal. This complication was interpreted as a coronary spasm. We discuss the causes for the spasm and the role that might have been played by the drugs employed.

Clinical importance of endothelial function in arteriosclerosis and ischemic heart disease

The vascular endothelium is a dynamic endocrine organ that regulates vascular tone, local homeostasis, and the fibro-inflammatory-proliferative process. These responses are mediated by various substances released from the endothelium in response to physiologic stimuli, including prostacyclin, endothelin and, most importantly, nitric oxide (NO). NO mediates vasodilation and inhibits platelet aggregation, thrombus formation, expression of adhesion molecules and chemokines for leukocytes, and oxidative stress. It also attenuates growth and proliferation of vascular smooth muscle cells. Risk factors for atherosclerosis, such as hypercholesterolemia, hypertension, diabetes and cigarette smoking, impair endothelial function, which leads to atherosclerosis and results in ischemic manifestations such as acute coronary syndrome and stroke. Thus, therapeutic intervention aimed at increasing NO bioavailability by statins or angiotensin-converting enzyme inhibitors might improve patient prognosis. Vascular endothelial function is an important and clinically relevant therapeutic target for cardiovascular disease.

The effects of resistance exercise on skeletal muscle abnormalities in patients with advanced heart failure

Resistance exercise increases muscular strength and endurance, which prevents injuries associated with musculoskeletal disorders, favorably alters muscle fiber type distribution, and up-regulates the genetic expression of certain enzymes seen in dysfunctional skeletal muscles. Although the benefits of resistance exercise are well documented in the literature, this form of exercise is not routinely recommended for patients with heart failure for fear of symptom exacerbation, and because of poor understanding of how best to prescribe this type of exercise. Because muscle atrophy and deconditioning states are common findings in patients with heart failure, these patients stand to benefit substantially from resistance training because this type of physical activity results in functional adaptations in the neuromuscular system. This article addresses changes in skeletal muscle pathophysiology that occur in patients with heart failure and the potential role resistance training may play in reversing this sequela, and recommends a weight lifting exercise prescription for these patients.

The T allele of the missense Glu(298)Asp endothelial nitric oxide synthase gene polymorphism is associated with coronary heart disease in younger individuals with high atherosclerotic risk profile

AIMS

Nitric oxide (NO) plays a protective role during atherogenesis. In the endothelium, NO is synthesised by the constitutive NO synthase (ecNOS). We analysed the relation of the ecNOS Glu(298)Asp and 4a/b gene polymorphisms to coronary artery disease (CAD) and myocardial infarction (MI) in a population of 3250 German subjects (533 healthy controls and 2717 individuals who underwent coronary angiography).

RESULTS

Although in the total sample, the ecNOS T allele was not associated with the risk of CAD (P=0.054) and the extent of this disease (P=0.078), a restriction to younger individuals (age</=61, mean age) revealed an association of the ecNOS T allele with an increased risk of CAD (1.43, 1.05-1.96; P=0.025) and with the severity of this disease (P=0.037). Similar observations were made in various high-risk populations. These associations were even more pronounced when the high-risk subgroups were restricted to younger individuals. For example, an odds ratio of 7.66 for CAD (95% CI, 2.0-29; P=0.003) was detected in diabetic individuals who were younger than 61 years. Also with respect to MI, the most pronounced associations of the ecNOS T allele with the risk of this disease were detected in younger individuals with at least one other cardiovascular risk factor. For example, in diabetics younger than 61 years, the relative risk for ecNOS T allele carriers was 9.73 (95% CI, 1.8-53; P=0.008). In contrast, the allele frequencies of the ecNOS 4a/b gene variation were essentially the same in controls and in CAD and MI patients.

CONCLUSION

The present data extends earlier observations by the findings that predominantly younger T allele carriers of the ecNOS Glu(298)Asp gene polymorphism with various coronary high-risk profiles had an increased risk to suffer CAD and/or MI. In contrast, no evidence was found for an association of the ecNOS 4a/b gene polymorphism with coronary heart disease.

Tetrahydrobiopterin improves coronary endothelial function, but does not prevent coronary spasm in patients with vasospastic angina

Reduced bioavailability of tetrahydrobiopterin (BH4), an essential cofactor for nitric oxide (NO) synthase, and the resulting decrease in NO in the coronary circulation may be involved in the pathogenesis of coronary spasm. The present study investigated the effects of BH4 on the vascular response to acetylcholine (ACh) in 28 patients with vasospastic angina (VA) using quantitative angiography. After recording the vascular responses to ACh (3 and 30 microg/min), either BH4 (1 mg/min) or saline was infused into the coronary artery for 2 min before and during a subsequent infusion of ACh. With the 3 microg/min dose of ACh, BH4 attenuated the ACh-induced decrease in coronary diameter in both the nonspastic segments (-1.1 +/- 2.2% ACh vs 6.0 +/- 2.8% ACh+BH4) and spastic segments (-6.3 +/- 2.7% ACh vs 2.9 +/- 2.7% ACh+BH4), but did not influence the ACh-induced coronary spasm at 30 microg/min (-57.3 +/-2.4% ACh vs -55.3 +/- 2.4% ACh+BH4). In the control patients, saline did not influence either the spastic or nonspastic vasoconstrictor responses to ACh. Acute administration of BH4 improves coronary endothelial function, but does not prevent coronary spasm in patients with VA.

Vascular endothelial dysfunction resulting from L-arginine deficiency in a patient with lysinuric protein intolerance

Although L-arginine is the only substrate for nitric oxide (NO) production, no studies have yet been reported on the effect of an L-arginine deficiency on vascular function in humans. Lysinuric protein intolerance (LPI) is a rare autosomal recessive defect of dibasic amino acid transport caused by mutations in the SLC7A7 gene, resulting in an L-arginine deficiency. Vascular endothelial function was examined in an LPI patient who was shown to be a compound heterozygote for two mutations in the gene (5.3-kbp Alu-mediated deletion, IVS3+1G-->A). The lumen diameter of the brachial artery was measured in this patient and in healthy controls at rest, during reactive hyperemia (endothelium-dependent vasodilation [EDV]), and after sublingual nitroglycerin administration (endothelium-independent vasodilation [EIV]) using ultrasonography. Both EDV and NO(x) concentrations were markedly reduced in the patient compared with those for the controls. They became normal after an L-arginine infusion. EIV was not significantly different between the patient and controls. Positron emission tomography of the heart and a treadmill test revealed ischemic changes in the patient, which were improved by the L-arginine infusion. Thus, in the LPI patient, L-arginine deficiency caused vascular endothelial dysfunction via a decrease in NO production.

Enhanced platelet aggregation in the coronary circulation after coronary spasm

A recently developed platelet aggregometer using a laser light scattering method is capable of monitoring the increase in size of small-sized platelet aggregates (diameter 9-25 microm), which cannot be detected with the conventional methods. Whether coronary spasm can cause platelet aggregation in the coronary circulation is unknown. We investigated platelet aggregation, especially small-sized platelet aggregates, simultaneously in the coronary sinus and the aortic root in 18 patients with coronary spastic angina before and after a left coronary artery spasm induced by intracoronary injection of acetylcholine, and in 15 patients with stable exertional angina before and after acute myocardial ischemia induced by rapid right atrial pacing. Platelet aggregation in 12 patients with chest pain syndrome was also examined before and after coronary spasms provoked by acetylcholine. The number of small-sized platelet aggregates increased significantly in the coronary sinus [2.0+/-0.6 x 104 to 4.1+/-1.0 x 104 (V), P<.01] and in the aortic root [1.7+/-0.6 x 104 to 3.2+/-0.6 x 104 (V), P<.05], and the coronary sinus-arterial difference in the number of small-sized platelet aggregates [2.3+/-1.9 x 103 to 1.1+/-0.4 x 104 (V), P<.01] increased significantly after attacks in the coronary spastic angina group, but remained the same in the stable exertional angina group after attacks and in the chest pain syndrome group after the administration of acetylcholine. Therefore, we can conclude that acute myocardial ischemia induced by coronary spasm causes platelet aggregation in the coronary circulation.

Circadian variation of autonomic nervous activity in patients with multivessel coronary spasm

The present study investigated whether the circadian rhythm of sympathovagal activity is related to the severity of coronary spasm or multivessel coronary spasm. Heart rate variability was examined in 22 consecutive patients with vasospastic angina provoked by intracoronary injection of acetylcholine, who had either multivessel spasm (Group M, n=11 ) or single vessel spasm (Group S, n= 11), in 20 subjects without coronary artery disease (Group C) and 20 patients with effort angina who had organic coronary artery stenosis (Group E). The frequency domain indices were analyzed, including low frequency (LF: 0.04-0.15 Hz) and high frequency (HF: 0.15-0.4Hz), the latter being an index of efferent parasympathetic activity, and the ratio (L/H) as an index of sympathovagal balance. The circadian variation of the parameters was analyzed by its pattern and was quantified by the difference of the mean values between daytime and nighttime. Although the HF power increased during nighttime in Groups C and S, this increase was attenuated in Groups E and M. The circadian variation of the L/H ratio (ie, a drop during nighttime) was smaller in the S and M groups than in Groups C and E. Accordingly, in Group M, the circadian variation of both sympathetic and parasympathetic nervous activity was attenuated, but in Group S, the variation of sympathetic nervous activity, but not parasympathetic nervous activity, was decreased. These data suggest that relatively enhanced sympathetic nervous activity at night may be involved in the mechanism underlying multivessel coronary spasm.

Clinical significance of preheparin serum lipoprotein lipase mass in coronary vasospasm

The present study investigated the clinical significance of preheparin serum lipoprotein lipase (LPL) mass in coronary vasospasm by examining its relationship with the acetylcholine-induced coronary artery response in patients without angiographically demonstrable atherosclerotic coronary artery disease (CAD). The subjects were 39 men who had suspected CAD and who underwent coronary angiography. Coronary vasospasm was defined as a marked luminal narrowing or total occlusion provoked by the intracoronary administration of acetylcholine. Preheparin LPL mass was lower (p<0.05) in 25 subjects in whom vasospasm was induced by the acetylcholine provocation test than in the 14 subjects with a negative response. As regards preheparin LPL mass, the subjects with multiple vessel spasm had significantly low concentrations (p<0.05) compared with single vessel spasm, although serum lipid levels were not significantly different. Multiple regression analysis revealed only preheparin LPL mass had a significant absolute t-value (2.016) among the coronary risk factors. Low preheparin LPL mass is interpreted as reflecting an impaired acetylcholine-induced coronary relaxation in coronary vasospasm and preheparin LPL mass may be useful as a marker of early stage coronary atherosclerosis that is not detectable by angiography.

Impaired endothelium-dependent vasodilation in the brachial artery in variant angina pectoris and the effect of intravenous administration of vitamin C

Endothelial dysfunction in the coronary artery contributes to the pathogenesis of variant angina, and endothelial dysfunction in variant angina may be associated with increased oxidant stress in the systemic arteries. We investigated whether endothelial dysfunction exists in the peripheral artery in patients with variant angina, and also examined the effect of vitamin C, an antioxidant, on endothelium-dependent vasodilation. Using high-resolution ultrasound, both the flow-mediated vasodilation (FMD, endothelium-dependent vasodilation) and sublingual nitroglycerin-induced vasodilation (NTG-D, endothelium-independent vasodilation) in the brachial artery were measured in 28 patients with variant angina and 24 control subjects who had normal coronary arteries. FMD was significantly impaired in patients with variant angina compared with control subjects (1.8 +/- 2.2% vs 6.4 +/- 4.9%, p <0.001). FMD and NTG-D before and after intravenous administration of either vitamin C or placebo were measured in 17 patients with variant angina. FMD significantly improved after the administration of vitamin C (from 2.2 +/- 2.4% to 4.5 +/- 1.6%, p <0.01), but not after administration of the placebo (from 2.0 +/- 2.6% to 1.7 +/- 1.9%). The improved FMD due to vitamin C in patients with variant angina, however, was not significantly different from that in the control subjects. NTG-D was not significantly different between patients with variant angina and control subjects (14.0 +/- 7.8% vs 13.6 +/- 5.0%) and it was also not affected by vitamin C.

IN CONCLUSION

(1) FMD in the brachial artery is impaired in patients with variant angina, and (2) the acute administration of the antioxidant, vitamin C, was observed to reverse this endothelial dysfunction. These findings support the theory that the systemic inactivation of nitric oxide due to oxidative stress might exist in patients with variant angina.

Increased autoantibodies against oxidized low-density lipoprotein in coronary circulation in patients with coronary spastic angina

Oxidized low-density lipoproteins are important in the progression of atherosclerosis. Autoantibodies against malondialdehyde-modified low-density lipoproteins have been reported to be predictive of the progression of atherosclerosis. This study sought to examine whether plasma levels of autoantibodies against oxidized low-density lipoprotein increase in the coronary circulation in patients with coronary spastic angina. The authors examined plasma antioxidized low-density lipoprotein antibody levels (activity unit values (AcU)/mL) simultaneously in the coronary sinus and the aortic root in 20 patients with coronary spastic angina, 23 patients with stable exertional angina, and 15 control subjects by measuring plasma levels of immunoglobulin G (IgG) autoantibodies against malondialdehyde-modified low-density lipoproteins by enzyme-linked immunosorbent assay. The plasma antioxidized low-density lipoprotein antibody levels (AcU/mL) in the coronary sinus increased in coronary spastic angina (38 +/- 16) compared with stable exertional angina (23 +/- 7) and control subjects (20 +/- 6) (p < or = 0.0001). The levels (AcU/mL) in the aortic root also increased in coronary spastic angina (33 +/- 12) compared with stable exertional angina (23 +/- 7) and control subjects (20 +/- 6) (p < 0.005). Furthermore, the coronary sinus-arterial differences of the levels (AcU/mL) were also higher in coronary spastic angina (5 +/- 9) than in stable exertional angina (0 +/- 6) and healthy subjects (-1 +/- 5) (p < 0.05). The generation of malondialdehyde-modified low-density lipoproteins is reported to be associated with atherothrombosis. These findings suggest that elevated levels of autoantibodies against malondialdehyde-modified oxidized low-density lipoproteins in coronary circulation are associated with the development of atherothrombosis from the progression of atherosclerosis rather than with the extent of coronary atherosclerosis in patients with coronary spastic angina.

Estradiol supplementation suppresses hyperventilation-induced attacks in postmenopausal women with variant angina

OBJECTIVES

We sought to examine whether estradiol (E2) supplementation suppresses anginal attacks in women with variant angina.

BACKGROUND

Estrogen is known to improve endothelial function. Coronary spasm plays an important role in the pathogenesis of not only variant angina but also ischemic heart disease in general, and endothelial dysfunction seems to be involved in the pathogenesis of coronary spasm.

METHODS

Fifteen postmenopausal women with variant angina (mean age 54.2 years) were given a hyperventilation (HV) test, a provocation test for coronary spasm, in the early morning of day 1 (baseline), day 3 (after 2-day transdermal E2 supplementation, 4 mg) and day 5 (after 2-day placebo administration). We measured the flow-mediated (endothelium-dependent) dilation (FMD) of the brachial artery with the ultrasound technique before each HV test.

RESULTS

The anginal attacks with ST segment elevation were induced by HV in all patients on days 1 and 5. However, no attacks were induced on day 3. Supplementation with E2 augmented FMD (3.5 +/- 0.6*, 8.9 +/- 0.7 and 4.0 +/- 0.5* on days 1, 3 and 5, respectively; *p < 0.01 vs. day 3). The serum E2 levels on days 1, 3 and 5 were 22.7 +/- 2.8*, 96.2 +/- 9.2 and 30.7 +/- 7.1* pg/ml, respectively (*p < 0.01 vs. day 3).

CONCLUSIONS

The present results demonstrated for the first time, to our knowledge, that E2 supplementation suppresses the HV-induced attacks in women with variant angina, in part because of the improvement of endothelial function.

Detection of the "midband" lipoprotein in patients with coronary artery spasm

BACKGROUND

Dyslipidemia in patients with coronary vasospasm has been characterized by a low level of high-density lipoprotein (HDL) cholesterol without elevation of low-density lipoprotein (LDL) cholesterol, distinct from patients with organic coronary artery disease.

HYPOTHESIS

Disordered triglyceride-rich lipoprotein metabolism may be linked to the genesis of coronary artery spasm.

METHODS

The incidence of the "midband" lipoprotein observed between very low-density lipoprotein (VLDL) and LDL bands in the polyacrylamide disc gel electrophoretic analysis was determined in 48 patients with coronary spastic angina (CSA), in 50 patients with stable effort angina and a significant fixed coronary stenosis (SEA), and in 40 control subjects without coronary artery disease (Control).

RESULTS

The incidence was significantly (p<0.05) higher in CSA (71%) than in SEA (50%) and Control (25%). Smoking was significantly (p < 0.05) more prevalent in CSA (77%) than in SEA (50%) and Control (50%). In SEA, serum levels of triglyceride and apoproteins C-II, C-III, and E were all significantly higher, and the serum level of HDL cholesterol was significantly lower in the midband-positive than in the midband-negative subgroup. In CSA, no significant differences were found in these serum levels between the midband-positive and -negative subgroups, except for a significantly (p < 0.05) lower level of HDL cholesterol in the former. However, a significantly (p < 0.05) higher incidence of diabetes mellitus or impaired glucose tolerance was noted in the midband-positive (41%) than in the midband-negative subgroup (7%) in CSA. The incidence of the detected midband lipoprotein was significantly decreased in the blood samples obtained from 20 of CSA after a > 6-month angina-free period (70-->25%, p < 0.05).

CONCLUSIONS

The midband lipoprotein was frequently detected in patients with coronary vasospasm, suggesting that dyslipidemia with disordered triglyceride-rich lipoprotein metabolism may be linked to the genesis of coronary artery spasm.

Nitric oxide-mediated vasodilatation is decreased in forearm resistance vessels in patients with coronary spastic angina

It has been reported that coronary endothelial dysfunction is associated with the pathogenesis of coronary spasm, and that endothelial nitric oxide (NO) mediated vasodilatation was decreased in coronary epicardial arteries in patients with coronary spastic angina (CSA). However, there are few reports about the endothelial function in peripheral resistance vessels of patients with CSA, so the present study investigated the role of NO in forearm resistance vessels in such patients. The responses of forearm blood flow to acetylcholine (ACh; 8-24 microg/min) and sodium nitroprusside (SNP; 0.4-1.2 microg/ml) infusions was examined using plethysmography, and subsequently the responses to ACh after an infusion of N(G)-monomethyl-L-arginine (L-NMMA; 4 micromol/min, for 5 min) in 17 patients with CSA and 17 age- and sex- matched controls. The vasodilator responses to ACh and SNP were comparable between the 2 groups (p=NS). L-NMMA significantly suppressed the vasodilator responses to ACh in controls (p<0.05), but there was no significant difference in the responses to ACh before and after infusion of L-NMMA in patients with CSA (p=NS). These results indicate that endothelial NO-mediated vasodilatation is decreased in the forearm resistance vessels of patients with CSA.

Increase in plasma levels of oxidized low-density lipoproteins in patients with coronary spastic angina

Oxidized low-density lipoproteins (LDL) impair endothelium-dependent dilation and constrict arteries. This study examined possible relation of the circulating plasma levels of Ox-LDL to coronary spastic angina (CSA). The plasma levels of Ox-LDL were measured by ELISA in 37 consecutive patients with CSA and normal coronary angiograms and in 79 consecutive control patients. The Ox-LDL levels in patients with CSA were significantly higher than those in controls. In multivariate analysis, higher levels of Ox-LDL were a risk factor for CSA independently of other traditional risk factors. The Ox-LDL levels had a significant and positive correlation with constrictor response of coronary arteries to the intracoronary acetylcholine infusion. Thus, Ox-LDL may play a possible role in pathogenesis of coronary spasm.

Coronary spastic angina induced by anticholinesterase medication for myasthenia gravis--a case report

Myasthenia gravis (MG) is characterized by weakness of skeletal muscles because of a decrease in the number of available acetylcholine receptors at neuromuscular junctions. Anticholinesterase medication is widely used to treat MG, but muscarinic side effects sometimes appear and limit the drug usage. To their knowledge, the authors present the first case of coronary spastic angina quite possibly induced by anticholinesterase medication to treat MG. The appearance of coronary spastic angina in the present case is likely mediated through the increase of acethylcholine by anticholinesterase medication.

The preventive effect of magnesium on coronary spasm in patients with vasospastic angina

STUDY OBJECTIVES

Previous studies have reported that magnesium (Mg) deficiency is associated with coronary spasm. However, little is known about the preventive effect of Mg on coronary spasm. The present study investigated whether Mg prevents coronary spasm in patients with vasospastic angina (VSA).

DESIGN

Effectiveness trial.

SETTING

University medical center.

PATIENTS

Twenty-two patients with VSA.

INTERVENTION

Coronary spasm was induced with an intracoronary infusion of acetylcholine (Ach). After spontaneous relief of the coronary spasm, Mg sulfate (0.27 mmol/kg body weight) was infused IV over 20 min in 14 patients and isotonic glucose was infused in 8 patients as control subjects. Intracoronary infusion of Ach was then repeated, and the diameter of the coronary arteries was measured quantitatively.

MEASUREMENTS AND RESULTS

Mg infusion caused coronary artery dilatation at baseline in both the spastic (5. 9 +/- 2.3%) and nonspastic segments (5.5 +/- 1.5%). Mg infusion reduced the severity of chest pain and ST-segment deviations during coronary spasm. After the Mg infusion, the percent change in the diameter of the spastic segments improved from - 62.8 +/- 2.6% to - 43.7 +/- 4.7% during coronary spasm. Overall, 10 of 14 patients (71%) responded favorably to Mg infusion. Isotonic glucose infusion did not elicit changes in chest pain severity, ST-segment deviations, or the diameter of the coronary arteries during spasm.

CONCLUSIONS

Mg infusion produces nonsite-specific basal coronary dilatation and suppresses Ach-induced coronary spasm in patients with VSA.

Lack of compensatory enlargement at sites of coronary vasospasm: identification by ultrasound and successful treatment with stenting

The case of a young man with spontaneous vasospasm at two sites in his left anterior descending coronary artery is described. Intravascular ultrasound demonstrated mild eccentric atherosclerosis with smaller total artery cross-sectional area (defined as the external elastic membrane) compared with reference segments. Impaired compensatory enlargement (remodeling) in response to mild atherosclerosis may derive from one or more biologic mechanisms that are also responsible for vasospasm. This characteristic is easily identified by intravascular ultrasound. In this case, coronary stenting of the vasospastic sites led to excellent long-term control of symptoms more than 1 year after intervention.

Modulation of contractions to ergonovine and methylergonovine by nitric oxide and thromboxane A2 in the human coronary artery

This study explored the modulatory effects of nitric oxide and thromboxane A2 on contractions to ergonovine and methylergonovine in human coronary arteries. To elucidate the different role of nitric oxide synthase in the response to the ergot alkaloids, the serotonin (5-HT) receptors involved in nitric oxide synthase in the response to the ergot alkaloids, the 5-HT receptors involved in nitric oxide release and the contraction of the vascular smooth muscle were characterized with more selective 5-HT-receptor agonists and antagonists. Rings of human coronary arteries from explanted hearts were suspended in organ chambers for isometric tension recording. After testing for contractile (potassium chloride, 60 mM) and endothelial function (substance P, 10(-8) M), respectively, they were exposed to ergot alkaloids or other agonists in the absence or presence of U 46619 (10(-9) M), or nitro-L-arginine (10(-4) M), or both. Ergonovine and methylergonovine were comparable, weak vasoconstrictors in untreated preparations. Contractions to ergonovine were augmented by U 46619, but not by nitro-L-arginine. Contractions to methylergonovine were augmented only by combining U 46619 and nitro-L-arginine. Serotonin and methylergonovine, but not ergonovine, elicited endothelium-dependent, nitric oxide-mediated relaxations. Nonselective 5-HT(1B/1D)-receptor stimulation caused both contractions and relaxations; selective 5-HT1B stimulation caused relaxations only. In the human coronary artery, contractions to ergonovine are not dependent on NO release but are synergistically augmented by thromboxane. Methylergonovine causes similar effects on the vascular smooth muscle, but contractions are inhibited by the release of NO from the endothelium. The 5-HT receptor on the endothelium appears to be different from the receptor on the vascular smooth muscle, which mediates the contractile response to the ergot alkaloids.

S-nitrosoglutathione reduces nonocclusive thrombosis rate following balloon overstretch injury and intracoronary irradiation of porcine coronary arteries

PURPOSE

Intracoronary radiation (IR) suppresses neointima formation following balloon injury in animal models. High doses of radiation exacerbate thrombosis and delay re-endothelialization. The free radical nitric oxide (NO) has been reported to inhibit platelet aggregation, reduce neointimal hyperplasia, and stimulate re-endothelialization. This study examined the effects of a chemical NO donor on neointima formation, thrombosis, and healing of irradiated porcine coronary arteries.

METHODS AND MATERIALS

Vascular lesions were created in the coronary arteries of 59 domestic swine by overstretch balloon injury. Arteries were then left untreated or were treated with intracoronary gamma-radiation using Iridium-192 in each artery to deliver 5 or 15 Gy at 2 mm from the center of the source. The chemical NO donor S-nitrosoglutathione (GSNO) was infused i.v. at a rate of 250 microg/min for 10 min before injury, followed by a continuous infusion for 60 min. Animals were euthanized at 14 days and their arteries were analyzed for histomorphometric indices of proliferation and thrombosis.

RESULTS

A dose of 15 Gy reduced the ratio of intimal area to medial fracture length (IA/FL) versus control (0.06 +/- 0.05 0.54 +/- 0.10 [p < 0. 001]) but increased the nonocclusive thrombosis rate compared to controls (85% vs. 30%; p < 0.05). A low dose of 5 Gy did not affect neointima formation. Treatment with GSNO reduced thrombosis in all treated groups: control, 15%; 5 Gy, 18%; and 15 Gy, 35% (p < 0.05) without affecting neointima formation.

CONCLUSION

Systemic administration of GSNO during balloon injury and IR was tolerated well by the swine and resulted in reduction of the thrombosis rate, especially at high doses, without apparent effect on neointima formation.

Intravascular ultrasound findings of negative arterial remodeling at sites of focal coronary spasm in patients with vasospastic angina

BACKGROUND

There are few data about the intravascular ultrasound (IVUS) findings in patients with vasospastic angina, especially regarding patterns of vascular remodeling.

METHODS AND RESULTS

Coronary spasm was documented by angiography and electrocardiographic evidence of ischemia in 36 patients after administration of ergonovine (cumulative doses up to 350 microg). After relief of spasm with 1000 microg of intracoronary nitroglycerin, quantitative angiography and IVUS imaging were performed and analyzed by standard methods. The 36 focal spasm sites were compared with the proximal and distal reference segments. The angiographic baseline minimum lumen diameter measured 1.78 +/- 0.66 mm, which decreased to 0.66 +/- 0.38 mm with ergonovine provocation (P <.0001), increased to 2.66 +/- 0.64 mm after intracoronary nitroglycerin (P <.0001 compared with baseline and after ergonovine), and did not change after IVUS imaging (2.66 +/- 0.63, P =.9). By IVUS, atherosclerotic lesions were observed at all coronary spasm sites; the mean plaque burden measured 56% at the spasm site and 35% at the reference. Spasm site plaque composition was hypoechoic in 31 and hyperechoic, noncalcific in 5; there was no calcium. The mean eccentricity index (maximum divided by minimum plaque thickness) was 6.7. Positive remodeling (spasm site arterial area greater than proximal reference) was present in 5; intermediate remodeling (proximal reference greater than spasm site greater than distal reference arterial area) was present in 7; and negative remodeling (spasm site arterial area less than distal reference) was present in 24.

CONCLUSIONS

Sites of vasospasm in patients with variant angina showed characteristics of early atherosclerosis, except for an unusually high incidence of negative arterial remodeling.

Decrease of nitric oxide end-products during coronary circulation reflects elevated basal coronary artery tone in patients with vasospastic angina

The aim of this study was to investigate the role of nitric oxide (NO) in the coronary circulation and its relation to basal coronary artery tone in patients with vasospastic angina (VSA). We evaluated the level of nitric oxide end-products (NOx; nitrite + nitrate) in coronary circulation blood using an HPLC-Griess system for nine patients with VSA and nine control patients. All of the patients with VSA experienced focal spasm in the proximal to middle segments of the left anterior descending coronary artery (LAD) in response to intracoronary injection of ergonovine maleate. The luminal diameter of the coronary artery was measured in each patient by quantitative coronary arteriography. Blood samples for NOx measurement were obtained from the coronary sinus (NOxV) and the ostium of the left coronary artery (NOxA). The NOx difference, calculated from the coronary venous-arterial difference in NOx, was close to zero for the control patients whereas it was clearly negative for the patients with VSA. In addition, the NOx difference in the patients with VSA showed a negative correlation with basal coronary artery tone (r = -0.91, p < 0.01) and a positive correlation with the dose of ergonovine required for spasm provocation (r = 0.77, p < 0.05). These results indicate that increased basal coronary artery tone and higher susceptibility to ergonovine in patients with VSA would be a consequence of coronary endothelial dysfunction as is indicated by NOx.

Diffuse intimal thickening of coronary arteries in patients with coronary spastic angina

OBJECTIVES

The purpose of this study was to evaluate the extent of atherosclerotic changes in angiographically normal coronary arteries using intravascular ultrasound (IVUS) technique in patients with coronary spastic angina.

BACKGROUND

Nitric oxide activity was shown to be decreased in coronary arteries of patients with coronary spastic angina (CSA). Decrease in nitric oxide causes arterial intimal hyperplasia or thickening. However, it remains unclear whether intimal thickening is diffusely present in coronary arteries of patients with CSA.

METHODS

The IVUS study was performed in 26 patients with CSA and with normal coronary angiograms and in 31 control subjects in whom age and gender was matched with those in patients with CSA.

RESULTS

Compared with control subjects, patients with CSA had significantly larger percent intima + media area (%I + M area), intima + media area and maximal intima + media thickness in all of proximal, middle and distal segments (p<0.01, respectively). Lumen area was comparable between these groups. The presence of spasm was the most powerful independent predictor of increase in percent intima + media area, in multiple-regression analysis with the traditional risk factors as covariates.

CONCLUSIONS

Intimal thickening existed entirely in a coronary artery in patients with CSA and with normal angiograms, independently of other traditional risk factors. The diffuse intimal thickening in the spasm coronary arteries is intimately related with coronary spasm.

Endothelial nitric oxide synthase gene mutation and human leukocyte antigen analyzed in three cases of familial vasospastic angina pectoris

A 50-year-old woman with rest angina underwent cardiac catheterization; coronary angiography in the presence of acetylcholine revealed 99% coronary spasm of the proximal left anterior descending artery. The patient's 82-year-old mother was also admitted to hospital with rest angina. Her Holter electrocardiogram showed ST-segment elevation during the attack at rest and coronary angiography showed 99% spasm of the right coronary artery and 90% spasm of the left coronary artery. Both women complained of chest pain during the spasm, which was accompanied by ST-segment depression. The 62-year-old brother of the original patient was also found to have coronary spasm of the left coronary artery. Human leukocyte antigen was analyzed in the 2 women: A2, B51, CW1, DR8 and DQ1 were common factors. A Glu298Asp point mutation of the endothelial nitric oxide synthase gene was investigated in both parents, their 2 daughters and 2 sons, but was not detected in the 3 patients, and was detected only in the 90-year-old father who did not suffer from angina. Nor was the T-786-C mutation found in the 3 cases. Other causes of familial spasm need to be elucidated.

Improvement of endothelial function and insulin sensitivity with vitamin C in patients with coronary spastic angina: possible role of reactive oxygen species

OBJECTIVES

This study was designed to examine the effect of antioxidant supplementation on the endothelial function and insulin sensitivity in patients with coronary spastic angina (CSA).

BACKGROUND

Insulin resistance may play a key role in coronary heart disease, and there is a possible link between acetylcholine-induced coronary vasoconstriction and hyperinsulinemia in patients with CSA. Endothelial dysfunction is present in the systemic arteries in CSA patients, and reactive oxygen species may cause inactivation of nitric oxide in these patients.

METHODS

We measured flow-mediated dilation of the brachial artery using ultrasound technique in 22 patients with CSA and 20 control subjects. We also evaluated glucose tolerance using a 75-g oral glucose tolerance test and insulin sensitivity using steady-state plasma glucose (SSPG) methods in the same patients.

RESULTS

The incidence of impaired glucose tolerance was higher in the CSA group than in the control group. Vitamin C infusion augmented flow-mediated dilation and decreased SSPG levels in the CSA group (from 3.27 +/- 0.77% to 7.00 +/- 0.59% [p < 0.001 by analysis of variance (ANOVA)] and from 177.3 +/- 13.3 to 143.1 +/- 14.9 mg/dl [p = 0.047 by ANOVA], respectively) but not in the control group (from 6.47 +/- 0.66% to 6.80 +/- 0.60% and from 119.8 +/- 11.7 mg/dl to 118.1 +/- 11.3 mg/dl, respectively). The steady-state plasma insulin levels were not affected by vitamin C infusion in either group.

CONCLUSIONS

Vitamin C improves both endothelial function and insulin sensitivity in patients with CSA. Thus, reactive oxygen species and/or decreased nitric oxide bioactivity may play an important role in the genesis of both endothelial dysfunction and insulin resistance in patients with CSA.

[Malondialdehyde and nitric oxide behaviour in patients with myocardial infarction]

INTRODUCTION AND OBJECTIVES

The aim of this study was to determine the potential usefulness of malondialdehyde and nitric oxide as sensors of metabolic damage produced during acute coronary ischaemics events.

METHODS

Serum malondialdehyde and nitric oxide levels were determined as thiobarbituric acid derivative and nitrites respectively in 15 male patients who were admitted to the emergency ward of the Hospital General del Sur de Maracaibo, because of acute stage of myocardial infarction.

RESULTS

Our results show, upon follow-up and afterwards 30 days a highly significant increase in the malondialdehyde level during the acute phase of myocardial infarction (1.87 +/- 0.29 vs 45.47 +/- 8.67 mM; p < 2.01 10-5) that returns to normal levels 30 days after myocardial infarction when compared with healthy subjects of the same age (1.87 +/- 0.29 vs 4.58 +/- 1.43 mM). As for nitric oxide, levels also increased significantly during the acute phase of myocardial infarction (41.25 +/- 3.59 vs 164.63 +/- 12.7, p < 2.13 10-10 mM) and diminished significantly when compared with healthy adults of the same age 30 days after the acute event (41.25 +/- 3.59 vs 40.85 +/- 4.50 mM).

CONCLUSIONS

Our results show that serum levels of malondialdehyde and nitric oxide increased significantly during acute infarction, coming back to normal levels 30 days after infarction, which suggest that both substances are potential tools to predict cardiac function recovery.

A T-786-->C mutation in the 5'-flanking region of the endothelial nitric oxide synthase gene and coronary arterial vasomotility

In the endothelium, synthesis of nitric oxide (NO) from the amino acid L-arginine is catalyzed by the endothelial NO synthase (eNOS), and the continuously generated NO serves to maintain basal vascular tone. Recently, we discovered a T-786-->C mutation in the 5'-flanking region of the eNOS gene; this mutation reduced the promoter activity of the eNOS gene and was associated with coronary spasm. We examined the vasomotility of the epicardial coronary artery in subjects with and without T-736-->C mutation. We examined vasomotility in 32 consecutive subjects who were heterozygotes for the T-786-->C mutation and in 68 subjects without the T-786-->C mutation who had equivalent age, sex, and smoking status at the proximal and distal segments of the left descending coronary artery by performing quantitative coronary angiography. In subjects with the mutant allele (-786C allele), basal diameters of proximal and distal segments before intracoronary injection of acetylcholine (ACh) were less than diameters in subjects without the mutant allele (p <0.05), although there was no difference between subjects with and without the mutant allele in the diameters of coronary arteries after isosorbide dinitrate (ISDN) administration. When we compared the changes in diameters, both ACh-induced vasoconstriction and ISDN-induced vasodilatation in subjects with the mutant allele were significantly increased in the proximal (p <0.01, p <0.001, respectively) and distal segments (p <0.03, p <0.01, respectively). Taken together, these findings strongly suggest that the T-786-->C mutation increases the basal tone of the coronary artery, and enhances the response to the constrictor effects of ACh and the dilator effect of ISDN because of reducing the endothelial NO synthesis.

Plasma adrenomedullin levels in the coronary circulation in vasospastic angina pectoris

This study evaluated the role of adrenomedullin in patients with vasospastic angina pectoris. Adrenomedullin may be involved in regulating a basal tone of the coronary artery in these patients.

Negative NO3- difference in human coronary circulation with severe atherosclerotic stenosis

To examine whether or not the levels of NOx (nitrite; NO2- and nitrate; NO3-) in coronary circulating blood reflect endothelial dysfunction due to coronary atherosclerosis, NOx levels in plasma obtained from ostium of left coronary artery and coronary sinus of patients who complained of chest pain were evaluated in relation to their coronary angiographic findings. Prior to the study, a HPLC-Griess system for NOx measurement was critically evaluated. This system has a detection limit of 0.1 microM of NO2- and NO3- by 10 microl of loading and was able to distinguish a difference of 0.1-0.2 microM of these substances. Heparin (1 U/10 microl) did not affect the detective and discriminative abilities. NO3- difference, calculated from sino-arterial difference of NO3-, was almost zero (-0.2 +/- 0.2 microM) in patients with either normal coronary arteries or mild organic coronary stenosis (< or = 20% narrowing), while a significant negative value (-5.9 +/- 1.7 microM) was obtained from patients with significant stenosis (> or = 70% narrowing) in the left coronary arteries. These results demonstrate reliable ability on the HPLC-Griess system in evaluating NO2- and NO3- in biological samples, and that the negative NO3- difference through coronary circulation may reflect endothelial dysfunction in the patients with coronary atherosclerosis with severe organic stenosis.

Formation of platelet aggregates after attacks of coronary spastic angina pectoris

Using a novel laser-light scattering method, we examined platelet aggregability, especially small-sized platelet aggregates, at baseline and after spontaneous coronary spastic attacks in 14 patients with coronary spastic angina, and before and after anginal attacks during an exercise test in 11 patients with stable exertional angina. The number of small-sized platelet aggregates after coronary spastic anginal attacks increased significantly, but not in patients with stable exertional angina. These results imply that an increase in the number of small-sized platelet aggregates from coronary spasm may be a trigger for coronary thrombosis via medium- and large-sized platelet aggregates.

Comparison of the risk factors for coronary artery spasm with those for organic stenosis in a Japanese population: role of cigarette smoking

We compared the risk factors for coronary spasm with those for coronary atherosclerosis in 183 patients with coronary spasm, 132 patients with coronary organic stenosis, and 224 control subjects with chest pain syndrome. Our findings confirmed that, when compared with controls, age, gender, total cholesterol, LDL-cholesterol, hypertension, diabetes mellitus, and cigarette smoking are all significant risk factors for coronary organic stenosis. On the other hand, only cigarette smoking proved to be a significant risk factor for coronary spasm. Also, when compared between coronary spasm group and coronary organic stenosis group, the incidence of cigarette smoking in males was significantly higher in the coronary spasm group than in the coronary organic stenosis group. We conclude that cigarette smoking is a crucial risk factor for coronary spasm. On the other hand, serum lipid levels and the incidence of hypertension and diabetes mellitus were within the normal ranges in the coronary spasm patients and were thus poorly associated with coronary spasm. These results showed that the risk factors for coronary spasm differ significantly from those for atherosclerosis-based coronary stenosis in the Japanese. Among the risk factors for coronary atherosclerosis (organic stenosis) smoking alone was a significant preventable risk factor for coronary artery spasm.

Myocardial ischemia due to coronary artery spasm during dobutamine stress echocardiography

Dobutamine stress echocardiography (DSE) is a useful and safe provocation test for myocardial ischemia. Until now, the test has been focused only on the organic lesion in the coronary artery, and positive DSE has indicated the presence of significant fixed coronary artery stenosis. The aim of the present study is to examine whether myocardial ischemia due to coronary spasm is induced by dobutamine. We performed DSE on 51 patients with coronary spastic angina but without significant fixed coronary artery stenosis. All patients had anginal attacks at rest with ST elevation on the electrocardiogram (variant angina). Coronary spasm was induced by intracoronary injection of acetylcholine, and no fixed coronary artery stenosis was documented on angiograms in all patients. DSE was performed with intravenous dobutamine infusion with an incremental doses of 5, 10, 20, 30, and 40 microg/kg/min every 5 minutes. Of the 51 patients, 7 patients showed asynergy with ST elevation. All 7 patients (13.7%) had chest pain during asynergy, and both chest pain and electrocardiographic changes were preceded by asynergy. These findings indicate that dobutamine can provoke coronary spasm in some patients with coronary spastic angina. When DSE is performed to evaluate coronary artery disease, not only fixed coronary stenosis, but also coronary spasm should be considered as a genesis of asynergy.