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At least 199 records · Page 11Linked to original sources
PubMed1997

Both endothelium-dependent and endothelium-independent function is impaired in patients with angina pectoris and normal coronary angiograms.

BACKGROUND: The aim of this study was to investigate both endothelium-dependent and endothelium-independent vasodilatation in syndrome X patients. Recently selective impairment of endothelium-dependent function has been reported in a small number of syndrome X patients. However, other investigators have reported impaired endothelium-independent function. METHODS: We infused the endothelium-independent vasodilators papaverine and glyceryl trinitrate, and endothelium-dependent vasodilator acetylcholine in the left coronary artery of 35 patients with syndrome X and in 17 control subjects (atypical chest pain, negative exercise test, and normal coronary angiograms). Coronary blood flow was measured with an intracoronary Doppler catheter positioned in the proximal left anterior descending coronary artery, and the artery diameter was assessed using quantitative coronary angiography. RESULTS: The mean increase in coronary blood flow in response to a 12 mg dose of papaverine was significantly less in the syndrome X group (185 +/- 74% vs 411 +/- 59%, P < 0.001). The increase in coronary blood flow in response to acetylcholine, at doses of 1, 3, 10, and 30 micrograms.min-1, was also significantly lower in the syndrome X group (12 +/- 13 (P < 0.05), 41 +/- 33, 57 +/- 68, and 124 +/- 87% (P < 0.001)) as compared to the control group (76 +/- 49, 214 +/- 116, 355 +/- 115, and 361 +/- 74%). CONCLUSION: These findings demonstrate that both endothelium-dependent and endothelium-independent dilatation of the coronary microvasculature is impaired in syndrome X.

Acetylcholine↗
PubMed2003

[Autonomic nervous system function in cardiologic syndrome X].

Syndrome X is defined as typical angina pectoris, positive treadmill exercise test, negative intravenous ergonovine test and angiographically normal coronary arteries. The pathogenesis of his syndrome is still not known. Alteration of autonomic nervous control of cardiac function have been described in syndrome X. The population of SX patients is heterogeneous having subgroup with normal and low abnormal autonomic system activity which in 40% of patients had normal heart regulation of autonomic system and in 60% we can observed abnormal regulation. It may be a result of high tonic sympathetic driver or low parasympathetic activity.

Angina Pectoris↗
PubMed1994

[Assessment of coronary flow reserve in patients with angina pectoris].

Coronary flow reserve was assessed by using a computer-assisted method in 26 normal controls and 45 patients with significant coronary artery stenosis ( > or = 50% luminal narrowing) and 16 patients with syndrome X. After intracoronary administration of papaverine, the diameter, cross sectional area, blood velocity, flow volume and reserve capacity of both left anterior descending (LAD) and right coronary arteries (RCA) were lower in patients with significant coronary stenosis than in controls. Despite similar changes in the diameter and cross sectional area, the velocity, flow volume and reserve capacity of these two vessels were also lower in patients with syndrome X than in controls. We conclude that coronary flow reserve is reduced in patients with coronary artery stenosis or syndrome X due to different levels of coronary artery abnormalities.

Angina Pectoris↗
PubMed1994

[Global change in the regulation of regional coronary flow in patients with single vessel coronary disease evidenced by positron emission tomography].

AIM OF THE STUDY: Aim of this study is to investigate whether, in patients with coronary artery disease (CAD), regional myocardial blood flow (rMBF) regulation is affected with further mechanisms besides the effects of epicardial coronary stenosis. MATERIAL AND METHODS: RMBF and coronary reserve are measured in 13 normal subjects and in 36 patients with effort angina and isolated (> or = 50% diameter narrowing) left anterior descending (LAD, 27 patients) or left circumflex (LCX, 9 patients) coronary artery stenosis. Measurements are obtained both at baseline and following dipyridamole (0.56 mg/kg in 4 minutes) using positron emission tomography and N13-ammonia. RESULTS: At rest, patients with CAD show similar rMBF values in the stenotic and remote areas (0.71 +/- 0.19 vs 0.77 +/- 0.22 ml/min/gr, respectively, ns); both values are significantly (p < 0.01) reduced with respect to mean rMBF observed in the normal subjects (1.07 +/- 0.21 ml/min/gr). Following dipyridamole, patients with CAD show lower rMBF values in stenotic than in control regions (1.25 +/- 0.54 vs 1.73 +/- 0.80 ml/min/gr, p < 0.01); however, both these values are significantly reduced when compared with mean rMBF in the normal subjects (3.76 +/- 0.88 ml/min/gr, p < 0.01). To evaluate whether reduction in resting myocardial perfusion indicates maximal vasodilatation, patients with CAD are divided into 2 groups: Group 1 with homogeneous baseline perfusion (0.73 +/- 0.2 vs 0.75 +/- 0.24 ml/min/gr, in stenotic and remote areas, respectively, ns), and Group 2 with baseline perfusion defect in the stenotic related territory (0.62 +/- 0.14 vs 0.84 +/- 0.17 ml/min/gr, p < 0.01). Coronary reserve (dipyridamole flow/baseline flow) is similar in the 2 Groups (1.74 +/- 0.66 vs 1.93 +/- 0.45, ns). CONCLUSIONS: These data suggest that, in patients with CAD, other factors beyond hydraulic effects of epicardial coronary stenosis, could modulate rMBF regulation; in fact: 1) myocardium perfused by angiographically normal coronary artery shows reduced values of both resting rMBF and coronary reserve; 2) myocardium supplied by stenotic vessel maintains a residual vasodilating capability despite a reduced baseline perfusion.

Aged↗
PubMed1995

[The noninvasive identification of patients with angina and normal coronary arteries].

BACKGROUND: Although patients with syndrome X (angina and normal coronary arteries, in absence of coronary spasm, cardiomyopathy or valvulopathy) and those with stable angina as well as documented coronary artery disease share a similar clinical presentation (effort related symptoms, positive exercise stress testing and reversible perfusion defects), their prognosis is markedly different. Coronary atherosclerosis is usually progressive relative to morbidity and mortality. Conversely prognosis both in terms of persistence of pain and mortality appears to be benign in syndrome X. Most cardiologists favor proceeding with coronary angiography in all patients presenting with exercise induced ST depression and reversible perfusion defects. However, it should not be assumed that this strategy will remain the preferred one. The aim of this study was to assess whether non invasive testing could identify underlying coronary artery anatomy, thus prognosis in the above subset of patients. The approach was selected on a clearly stated objective of how isosorbide dinitrate and verapamil may influence coronary flow reserve, thus exercise stress testing in syndrome X. Nitrates have been shown to reduce coronary flow reserve during stress tachycardia. The opposite occurs with calcium blockers. METHODS: We studied 48 patients with effort angina referred to our laboratory for diagnostic evaluation. All patients underwent two separate sessions at one-day interval. Each session consisted of exercise stress testing before and after isosorbide dinitrate (s.l.; 5-10 mg) or verapamil (i.v.; 10 mg), given in a randomized crossover fashion. Angiography was performed within 3 months from testing. Efficacy of drugs in terms of exercise capacity was assessed by using the following criteria: 1) prevention of significant (> or = 0.1 mV) ST depression while reaching same workload levels attained during baseline testing; 2) improvement in the ischemic thresholds, that is an increase in: time to 0.1 mV ST depression > or = 120 sec., with heart rate (> or = 10 bpm) and rate pressure product (> or = 2 U x 1000) greater than those attained during baseline testing; 3) increase in time to peak exercise (> or = 120 sec). RESULTS: In syndrome X, both drugs resulted ineffective in one patient, one patient showed a favourable response to isosorbide dinitrate whereas the remaining 13/15 patients improved exercise capacity following verapamil, but not isosorbide dinitrate. The opposite occurred in coronary artery disease patients: both isosorbide dinitrate and verapamil were effective in 21/33 patients, and ineffective in 8/33 patients. The remaining 4 patients responded to isosorbide dinitrate but not to verapamil. CONCLUSIONS: 1) Verapamil, but not isosorbide dinitrate, improves exercise capacity in syndrome X; 2) this does not apply to patients with stable angina; 3) a favourable response to verapamil but not to isosorbide dinitrate is both a sensitive (86%) and specific (100%) method for identifying patients with angina and normal coronary arteries; 4) non invasive testing may select those effort angina patients who have to proceed directly to coronary angiography; 5) some patients with effort related angina may not require further investigation.

Adult↗
PubMed1998

Effects of spinal cord stimulation on coronary blood flow velocity.

BACKGROUND: Spinal cord stimulation (SCS) has been used in the treatment of severe angina pectoris since the 1980s. Several studies have shown both an antianginal and an anti-ischaemic effect. There are several theories about the mechanism behind the anti-ischaemic effect of SCS, including the possibility that it is dependent on an increase in coronary flow velocity. OBJECTIVE: To determine if there were effects of SCS on coronary flow velocity during cardiac stress. METHOD: Eight patients with severe anginal pain secondary to coronary artery disease who had been implanted with an SCS device were included in the study. In addition, four patients with syndrome X were examined. If possible, a Doppler guidewire was placed in the vessel corresponding to the ischaemic area revealed on a prior myocardial scintigram. A temporary pacemaker electrode was placed in the right atrium. Atrial pacing started at 80 beats/min and increased by 10 beats/min every 2 min until the patient experienced moderate angina; the pacing frequency was then maintained at the same level. After 2 min of pacing at this frequency, SCS treatment commenced; after a further 5 min, pacing was stopped. Throughout the procedure, coronary flow velocity, assessed as average peak velocity (APV), was monitored continually. RESULTS: APV increased during pacing in all the patients with coronary artery disease (mean increase 53%; P < 0.02). There were no significant changes in APV during maximum pacing frequency when stimulation was introduced. CONCLUSIONS: The results of this study do not support the theory that the anti-ischaemic effect of SCS is dependent on an increase in coronary flow velocity.

Angina Pectoris↗
PubMed1997

Effects of bamiphylline on exercise testing in patients with syndrome X.

An abnormal stimulation of adenosine A1-receptors has been suggested to play a role in the pathogenesis of both chest pain and ischemia-like electrocardiographic changes in patients with syndrome X and a nonselective adenosine antagonist (theophylline) has been reported to be beneficial in these patients. In this study we investigated the acute effects of bamiphylline, a specific A1-receptor antagonist, in 16 patients with syndrome X (14 women, age 57 +/- 6 years), with both angina and ST-segment depression inducible during exercise testing. All patients underwent two treadmill exercise tests (Bruce modified protocol) on 2 separate days, 5 minutes after the end of randomized intravenous infusion of either placebo (saline solution) or bamiphylline (300 mg). Severity of chest pain was assessed by a 100 mm visual analogic scale. There were no significant differences in resting heart rate and blood pressure after bamiphylline or placebo. Rate-pressure product (20 600 +/- 5000 vs 20 200 +/- 5200 bpm.mmHg), time to 1 mm ST depression (549 +/- 196 vs 581 +/- 201 sec), time to angina (519 +/- 209 vs 571 +/- 196 sec), and exercise duration (717 +/- 134 vs 676 +/- 166 sec) were also not significantly different after bamiphylline or placebo, but there was a mild reduction of the severity of exercise-induced chest pain (30 +/- 22 vs 39 +/- 20 mm, p < 0.05) with the active drug. Thus, in patients with syndrome X, bamiphylline does not improve exercise-induced ST changes, suggesting that A1-receptors are not significantly involved in their appearance. In addition, bamiphylline had little effect on anginal pain, suggesting that this cannot be mediated exclusively by A1-receptor stimulation in these patients.

Angina Pectoris↗
PubMed2001

Differential coronary calcification on electron-beam CT between syndrome X and coronary artery disease in patients with chronic stable angina pectoris.

STUDY OBJECTIVES: The differential diagnosis of syndrome X and coronary artery disease (CAD) in patients with evidence of myocardial ischemia may be difficult. The possible difference in coronary calcium detected by electron-beam CT (EBCT) between syndrome X and CAD is rarely evaluated, especially in aged patients with chronic, stable angina. DESIGN AND SETTINGS: Prospective, controlled study at a tertiary referral medical center. PATIENTS AND MEASUREMENTS: Forty patients with syndrome X (85% male) and 53 patients with CAD (89% male) were enrolled. Ten control subjects (90% male) with negative exercise treadmill test results and normal coronary angiographic findings served as control subjects. EBCT determined the coronary calcium scores (CCSs), and standard cardiovascular risk factors of all study subjects were analyzed. RESULTS: The 93 study patients had CCSs that ranged from 0 to 1,857. Coronary calcification was seen in 2 of the 10 control subjects (20%), 21 of the 40 syndrome X patients (52.5%), and 51 of the 53 CAD patients (96.2%) [p < 0.01]. The CCS (median [range]) was significantly lower in syndrome X patients than in CAD patients: 1 (0 to 117) vs 202 (0 to 1,857) [p < 0.001]. Receiver operating characteristic curve analyses also demonstrated that coronary calcification differentiated syndrome X from CAD (area under curve, 0.891; 95% confidence interval, 0.806 to 0.947). Of the CAD patients whose CCSs were < 117 and overlapped with CCSs of syndrome X, multivariate analyses determined CCS > 5 (odds ratio, 13.1; 95% confidence interval, 2.86 to 59.7), hypertension (odds ratio, 6.4; 95% confidence interval, 1.5 to 27.4), and hypercholesterolemia (odds ratio, 6.7; 95% confidence interval, 1.5 to 30.5) to be independent discriminators to differentiate CAD from syndrome X. Patients with CAD had more frequent hypertension than patients with syndrome X. CONCLUSIONS: The coronary calcium detected noninvasively by EBCT was different, though with some overlapping, between patients with syndrome X and CAD. In addition to standard cardiovascular risk factors, CCS determined by EBCT (especially > 117 or = 0) could differentiate between syndrome X and CAD in patients with chronic, stable angina with evidence of myocardial ischemia. Larger trials would be useful to validate CCS on EBCT as a predictor of clinical outcome in these patients.

Adult↗