ISSN:0009-7322    

出版商:OVID    

年代:1995

数据来源: OVID

ISSN:0009-7322    

出版商:OVID    

年代:1995

数据来源: OVID

ISSN:0009-7322    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

BackgroundAnomalous coronary arteries are a rare but recognized cause of myocardial ischemia and sudden death. Identification currently requires x-ray angiography, which may have difficulty defining the three-dimensional course of the anomalous vessel. Magnetic resonance coronary angiography (MRCA) has been shown to image coronary artery anatomy noninvasively. We hypothesize that MRCA may be useful in the identification of anomalous coronary arteries and their anatomic course.Methods and ResultsSixteen patients (9 men, 7 women, age 44 to 81 years) with anomalous aortic origins of the coronary arteries by conventional x-ray angiography underwent MRCA. Multiple images of the major epicardial coronary arteries were obtained by use of a breathhold, fat-suppressed, segmented-k space, gradient-echo technique by investigators blinded to all patient data. Anomalous coronary artery pathology, by x-ray angiography, included right-sided left main coronary artery (n = 3), right-sided left circumflex artery (n = 6), separate left-sided left anterior descending and left circumflex arteries (n = 2), left-sided right coronary artery (n = 4), and an anteriorly displaced right coronary artery (n = 1). MRCA correctly identified the anomalous coronary vessel(s) in 14 of 15 patients. In 1 patient, the anomalous vessel was incorrectly identified, and in 2 patients the course of the anomalous vessel was not clearly seen; one of these was a nondominant, anomalous right coronary artery.ConclusionsMRCA is a useful technique for the noninvasive identification of anomalous coronary arteries and their anatomic course. (Circulation. 1995;92:3158-3162.)Key Wordsarteries, angiography, magnetic resonance imaging.

ISSN:0009-7322    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

BackgroundThe clinical significance of anomalously originating coronary arteries depends on their proximal course. Diagnosis of this course by conventional x-ray coronary angiography alone may be equivocal. We postulated that with fast magnetic resonance (MR) angiography, accurate detection of anomalous coronary arteries and unambiguous delineation of their proximal course is feasible.Methods and ResultsIn a selected group of 38 patients, 19 of them having an anomalously originating coronary artery, a fast MR angiographic technique was used to study the proximal coronary anatomy. Blinded analysis of randomly ordered MR studies was performed independently by two observers. Both origin and proximal course of the coronary arteries were defined. Two cardiologists reviewed all x-ray coronary angiograms. After the separate analyses, a final consensus result was defined for each patient. In 37 patients, successful MR coronary angiography could be performed. Interobserver agreement for determining both origin and proximal course was 100%. An x-ray coronary angiogram was available in 36 patients. In 3 patients (all with an anomalous left main coronary artery originating from the right aortic sinus), there was disagreement about the proximal course between the results of MR and x-ray coronary angiography. Review of these cases demonstrated that MR angiography had unambiguously visualized the proximal coronary artery course, whereas the results of x-ray angiography had been equivocal. Thus, sensitivity and specificity for detecting anomalous coronary arteries and delineating their proximal course were 100%.ConclusionsThese data suggest that fast MR angiography is highly accurate in determining the origin and delineating the proximal course of anomalous coronary arteries, even in those cases in which x-ray coronary angiographic diagnosis is difficult or even erroneous. (Circulation. 1995;92:3163-3171.)Key Wordsangiography, magnetic resonance imaging, arteries, coronary disease, heart defects, congenital.

ISSN:0009-7322    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

BackgroundHypercholesterolemia is a risk factor for coronary disease, and platelet reactivity is increased with hypercholesterolemia, suggesting a prethrombotic risk. The aim of this study was to measure mural platelet thrombus formation on an injured arterial wall in a model simulating vessel stenosis and plaque rupture in hypercholesterolemic coronary disease patients before and after cholesterol reduction.Methods and Results5.2 mmol/L) before and after a mean of 2.5 months of pravastatin therapy (40 mg/d) and in 16 normocholesterolemic control patients. Thrombus formation was assessed by exposing porcine aortic media to the patient's flowing venous blood for 3 minutes at a shear rate of 754 or 2546 s sup -1 at 37 degrees Celsius in an ex vivo superfusion chamber. Quantitative morphometric platelet thrombus formation at baseline was higher in the hypercholesterolemic patients at both the high and low shear rates: 4.8 plus/minus 1.0 and 3.3 plus/minus 0.7 micro meter2/mm, respectively, compared with normocholesterolemic patients: 2.1 plus/minus 0.5 and 1.6 plus/minus 0.4 micro meter2/mm (both P < .05). In the hypercholesterolemic patients, pravastatin decreased total cholesterol from 6.5 plus/minus 0.2 to 4.5 plus/minus 0.2 mmol/L and LDL cholesterol from 4.5 plus/minus 0.2 to 2.8 plus/minus 0.1 mmol/L (both P < .05). Platelet thrombus formation at high and low shear rates decreased to 2.0 plus/minus 0.3 and 1.3 plus/minus 0.3 micro meter2/mm, respectively (both P < .05).ConclusionsThus, hypercholesterolemia is associated with an enhanced platelet thrombus formation on an injured artery, increasing the propensity for acute thrombosis. Platelet thrombus formation at both high and low shear rates decreased as total and LDL cholesterol levels were reduced with pravastatin. Cholesterol lowering may therefore reduce the risk of acute coronary events in part by reducing the thrombogenic risk. (Circulation. 1995;92:3172-3177.)Key Wordscholesterol, pravastatin, platelets, thrombosis, coronary disease.

ISSN:0009-7322    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

BackgroundThe purpose of this study was to examine prospectively the relation of shift work to risk of coronary heart disease (CHD) in a cohort of women.Methods and ResultsAn ongoing prospective cohort of US female nurses, in whom we assessed (in 1988) the total number of years during which they worked rotating night shifts (at least three nights per month in addition to day and evening shifts), included 79 109 women, 42 to 67 years old in 1988, who were free of diagnosed CHD and stroke. Incident CHD was defined as nonfatal myocardial infarction and fatal CHD. During 4 years of follow-up (1988 to 1992), 292 cases of incident CHD (248 nonfatal myocardial infarction and 44 fatal CHD) occurred. The age-adjusted relative risk of CHD was 1.38 (95% CI, 1.08 to 1.76) in women who reported ever doing shift work compared with those who had never done so. The excess risk persisted after adjustment for cigarette smoking and a variety of other cardiovascular risk factors. Compared with women who had never done shift work, the multivariate adjusted relative risks of CHD were 1.21 (95% CI, 0.92 to 1.59) among women reporting less than 6 years and 1.51 (95% CI, 1.12 to 2.03) among those reporting 6 or more years of rotating night shifts.ConclusionsThese data are compatible with the possibility that 6 or more years of shift work may increase the risk of CHD in women. (Circulation. 1995;92:3178-3182.)Key Wordscoronary disease, stress, circadian rhythm, women.

ISSN:0009-7322    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

BackgroundFractional flow reserve (FFR), defined as the ratio of maximum flow in the presence of a stenosis to normal maximum flow, is a lesion-specific index of stenosis severity that can be calculated by simultaneous measurement of mean arterial, distal coronary, and central venous pressure (Pa, Pd, and Pv, respectively), during pharmacological vasodilation. The aims of this study were to define ranges of FFR values, whether associated with inducible ischemia or not, and to investigate FFR in normal coronary arteries.Methods and ResultsIn 60 patients accepted for percutaneous transluminal coronary angioplasty (PTCA) of single-vessel disease, with a positive exercise test (ET) < 24 hours before PTCA, FFR was determined during adenosine-induced hyperemia just before and 15 minutes after angioplasty. Pawas measured by the guiding catheter, Pdby an 0.018-in fiber-optic pressure-monitoring wire, and Pvby a multipurpose catheter. The ET was repeated after 5 to 7 days, and only if this second ET had reverted to normal was the pre-PTCA value of FFR definitely considered to be associated with inducible ischemia and the post-PTCA value not.Myocardial FFR (FFR sub myo) increased from 0.53 plus/minus 0.15 before PTCA to 0.88 plus/minus 0.07 after PTCA. Coronary FFR increased from 0.38 plus/minus 0.19 to 0.83 plus/minus 0.12. In all patients, values of FFRmyodefinitely associated with ischemia were less or equal to 0.74, whereas all except two values not associated with inducible ischemia exceeded 0.74. Moreover, FFRmyoin 18 coronary arteries in 5 normal patients equaled 0.98 plus/minus 0.03.ConclusionsA value of FFRmyoof 0.74 reliably discriminates coronary stenosis, whether associated with inducible ischemia or not. Therefore, FFRmyois a useful index to determine the functional significance of an epicardial coronary stenosis and may facilitate clinical decision making in patients with an equivocal coronary stenosis. (Circulation. 1995;92:3183-3193.)Key Wordsfractional flow reserve, collateral circulation, blood flow.

ISSN:0009-7322    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

BackgroundAntithromboxane therapy with aspirin reduces acute procedural complications of coronary angioplasty (PTCA) but has not been shown to prevent restenosis. The effect of chronic aspirin therapy on long-term clinical events after PTCA is unknown, and the utility of more specific antithromboxane agents is uncertain. The goal of this study was to assess the effects of aspirin (a nonselective inhibitor of thromboxane A2synthesis) and sulotroban (a selective blocker of the thromboxane A2receptor) on late clinical events and restenosis after PTCA.Methods and ResultsPatients (n = 752) were randomly assigned to aspirin (325 mg daily), sulotroban (800 mg QID), or placebo, started within 6 hours before PTCA and continued for 6 months. The primary outcome was clinical failure at 6 months after successful PTCA, defined as (1) death, (2) myocardial infarction, or (3) restenosis associated with recurrent angina or need for repeat revascularization. Neither active treatment differed significantly from placebo in the rate of angiographic restenosis: 39% (73 of 188) in the aspirin-assigned group, 53% (100 of 189) in the sulotroban group, and 43% (85 of 196) in the placebo group. In contrast, aspirin therapy significantly improved clinical outcome in comparison to placebo (P = .046) and sulotroban (P = .006). Clinical failure occurred in 30% (49 of 162) of the aspirin group, 44% (73 of 166) of the sulotroban group, and 41% (71 of 175) of the placebo group. Myocardial infarction was significantly reduced by antithromboxane therapy: 1.2% in the aspirin group, 1.8% in the sulotroban group, and 5.7% in the placebo group (P = .030).ConclusionsThromboxane A2blockade protects against late ischemic events after angioplasty even though angiographic restenosis is not significantly reduced. While both aspirin and sulotroban prevent the occurrence of myocardial infarction, overall clinical outcome appears superior for aspirin compared with sulotroban. Therefore, aspirin should be continued for at least 6 months after coronary angioplasty. (Circulation. 1995;92:3194-3200.)Key Wordsangioplasty, myocardial infarction, aspirin, platelets, restenosis.

ISSN:0009-7322    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

BackgroundCoronary endothelium plays a key role in the regulation of coronary tone, platelet adhesion, and aggregation, which are important factors in triggering acute cardiovascular events. However, its role in modulating the effects of circadian variations on coronary tone is not known.Methods and ResultsResponses of 72 nonstenotic coronary segments to acetylcholine and nitroglycerin were measured in 12 patients with chronic stable angina at 6 AM and 1 PM. After baseline angiography, three infusions of acetylcholine (10 sup -6, 10 sup -5, and 10 sup -4 mol/L) were administered selectively into the left coronary artery, followed by nitroglycerin. Diameters (in millimeters) of proximal, middle, and distal segments were measured by quantitative techniques. Forty-seven segments showed a constrictor response to acetylcholine (group 1, dysfunctional endothelium), and 25 other segments showed a dilator response (group 2, normally functioning endothelium). In group 1, the constrictor response to acetylcholine was significantly greater in the morning than in the afternoon (23 plus/minus 3% and 10 plus/minus 1%, mean plus/minus SEM, respectively; P < .001), and the dilator response to nitroglycerin was also significantly greater in the morning than in the afternoon (19 plus/minus 2% and 11 plus/minus 2%; P < .01). In group 2, the dilator response to acetylcholine did not differ significantly between the morning and afternoon (22 plus/minus 3% and 17 plus/minus 2%, respectively; P = NS), and the dilator response to nitroglycerin was also similar at both times of the day (30 plus/minus 3% and 28 plus/minus 4%, respectively; P = NS).ConclusionsCoronary segments with dysfunctional endothelium exhibit an early morning exaggeration in vasomotor activity, whereas segments with normally functioning endothelium do not show circadian variations. This suggests a potential protective role for the endothelium in modulating variations in coronary tone that may contribute to increased incidence of cardiovascular events in the early morning hours. (Circulation. 1995;92:3201-3205.)Key Wordsacetylcholine, angiography, circadian rhythm, coronary disease.

ISSN:0009-7322    

出版商:OVID    

年代:1995

数据来源: OVID