Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0151744 (myocardial ischemia)
 31,282 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Measurements of regional myocardial blood flow have been performed rapidly and safely in man at the time of coronary arteriography. Xenon-133 was injected into the coronary artery and estimates of myocardial capillary perfusion were made by computer analysis of the multiple precordial tracer washout curves recorded with a scintillation camera. Blood flow rates/100 g/min in different areas of the heart were calculated by the Schmidt-Kety formula, using an assumed partition coefficient, and were related to the coronary vascular lesions by landmarks provided by the arteriograms. The flow significance of lesions was assessed by making measurements at rest and during interventions that increase coronary blood flow. Perfusion was also estimated in areas supplied by collateral vessels, and regions of scar were detected from the initial distribution of peak tracer activity. In patients with less than 50% obstructions apparent on coronary arteriograms and in those with greater than 50% isolated left anterior descending lesions average mean left ventricular (LV) myocardial perfusion values were not reduced below values found in patients with normal coronary arteries and normal cardiac function. However, in patients with significant two-vessel disease (LAD + right, LAD + circ) mean LV perfusion was significantly reduced. Average regional myocardial perfusion distal to significant lesions was not selectively reduced below the remainder of the ventricle unless the lesions were 100% obstructions. However, both total and distal regional myocardial perfusion increased less in 12 patients with greater than 50% lesions than in 12 others with normal arteriograms or less than 50% lesions. Subnormal flow responses in all of the former group were associated with angina pectoris compared with no angina in the latter. The studies indicate the potential utility of the measurements of regional myocardial blood flow in the evaluation of patients with ischemic heart disease who are potential candidates for myocardial revascularization procedures.
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PMID:Studies of regional myocardial blood flow: results in patients with left anterior descending coronary artery disease. 94 Oct 26

By employing 133 Xenon injections and a gamma camera recording of the initial uptake and subsequent disappearance of the tracer, regional myocardial perfusion rates were determined in 38 patients with ischaemic heart disease. Areas supplied by collaterals and areas devoid of them were analyzed separately. In addition to determining basal flow rates, the regional perfusion was studied by repeated 133Xenon scintigrams during pacing-induced ischaemia. The data were grouped and analyzed according to the visual assessment of collateral response as observed in the angiograms performed under the same circumstances. Eleven patients who did not have collaterals on their angiograms were excluded, as were three patients in whom the collaterals were supplying segments distal to only subtotal obstructions leaving 24 patients to the study proper. Angiographic appraisal disclosed two different responses to ischaemia: ten patients exhibited an increase in the collateral pattern (responders) and 14 patients showed no change or reduction in the collaterals (nonresponders). The prepacing grading of the collaterals was similar in the subgroups. Under basal conditions the regional myocardial flow rates in areas supplied by collaterals or devoid of them were roughly similar. Upon ischaemia the greatest regional flow increment occurred in the responders. The data demonstrate a reasonable agreement between the visual assessment of collateral response to ischaemia and a change in the regional perfusion. The data further indicate that similar collateral patterns observed by routine coronary angiography are not functionally equipotent.
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PMID:Radiologically detected collaterals and regional myocardial flow responses to ischaemia in ischaemic heart disease. 99 9

Carbon monoxide diffusion (DLCO), blood gas analysis at rest and after exercise, distribution of ventilation and perfusion by Xenon 133 were carried out in 43 hyperlipidemic patients, Fredrickson's types I, IIA, IIB, and IV. DLCO was significantly reduced in hypertriglyceridemic and to a lesser degree in hypercholesterolemic patients. A significant negative correlation was found between DLCO and triglyceride values. Significantly lower basal PaO2 values, which improved after exercise, were observed in both type IIA and type IV hyperlipemic patients. The ventilation/perfusion ratio distribution (V/Q) did not increase from the basal to the apical segments of the lungs in hyperlipidemic patients as it did in normals. The hypothesis of an alteration in pulmonary surface-active lipoprotein, directly related to hyperlipoproteinemia or indirectly caused by fat microembolism, may explain the reduced DLCO, the loss of V/Q gradient, and the decrease in PaO2 (which improves after exercise) observed in hyperlipemic patients. Disturbances in pulmonary gas exchange and PaO2 reduction could play an important role in the pathogenesis of both angina pain due to ischaemic heart disease, which is frequently observed in hyperlipemic patients, and the postprandial angina syndrome.
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PMID:Disturbances in pulmonary gaseous exchange in primary hyperlipoproteinemias. 101 88

Myocardial imaging with Xenon-133 and a gamma camera was employed to evaluate the relationship between angiographically demonstrated coronary artery stenosis and regional myocardial blood flow (r-MBF) in 22 patients with ischemic heart disease and 9 control subjects. After a left anterior oblique cineangiogram was obtained, the cinecamera was replaced by the mobile gamma camera in the same plane and location over the pericardium of patients. Then, 370 MBq (10 mCi) of 133Xe was injected into the left coronary artery as a bolus. After the first measurement of r-MBF in resting state, a second injection was made 3 minutes after intravenous injection of 0.56 mg/kg of dipyridamole for 4 minutes. The r-MBF in different regions of the heart was calculated by Kety formula. Coronary flow reserve (CFR) was defined the rMBF ratio between resting and dipyridamole induced vasodilative state. In the resting state, good correlation (r = 0.711) was observed between pressure rate product and the r-MBF at the areas perfused by non stenotic vessels. The r-MBF of the areas perfused by severe stenotic vessels (greater than 90%) was smaller than that of the areas perfused by non stenotic vessels, however there was overlapping of flow. In the dipyridamole induced vasodilative state, the r-MBF of the areas perfused by intact vessels increased approximately 2.4 times of the resting state, and showed good correlation with pressure rate product. In contrast, the r-MBF of the areas perfused by stenotic vessels did not correlate with pressure rate product, but depended on the degrees of coronary stenosis (50-75% stenosis; 1.9 times, greater than 90% stenosis; 1.3 times, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Regional myocardial blood flow measurements in resting and dipyridamole induced vasodilative state by Xenon-133 clearance method]. 221 28

Although in vitro studies have demonstrated ethanol-induced coronary artery constriction, in vivo reports suggest an ethanol-related coronary dilator effect with increases in coronary blood flow. The principal difference in these studies is the demonstration of epicardial coronary constriction with ethanol, while dilation is described only in resistance vessels. Clinical studies have noted evidence of myocardial ischemia following ethanol ingestion in patients with coronary artery disease, suggesting ethanol-related constriction of diseased epicardial coronary arteries. This study hypothesized that intravenous ethanol would constrict canine epicardial coronary arteries while producing arteriolar resistance vessel dilatation. Ten closed-chest mongrel dogs weighing 24 +/- 1 kg (mean +/- SEM) were given 8 g of ethanol intravenously over 30 min. Left anterior descending and circumflex proximal artery diameters were measured by quantitative coronary angiography; myocardial flow was measured by Xenon washout, and myocardial flow distribution was measured with radioactive microspheres. Baseline proximal left anterior descending and circumflex artery areas were 6.3 +/- 0.5 and 5.8 +/- 0.4 mm2, respectively. Up to 30% left anterior descending and circumflex proximal artery narrowing was noted at 60 and 90 min following ethanol infusion. The constriction was reversed with nitroglycerin. There was a decrease in left anterior descending artery flow but no change in circumflex artery flow at 60 min. Blood ethanol level varied from 520 micrograms/ml initially to 205 micrograms/ml 90 min after the infusion terminated (intoxication = 1500 micrograms/ml). These data suggest that ethanol has significant vasoconstrictor action in vivo on epicardial coronary arteries.
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PMID:Epicardial coronary artery constriction with intravenous ethanol. 270 11

Xenon anaesthesia appears to have minimal haemodynamic effects. The purpose of this randomised prospective study was to compare the cardiovascular effects of xenon and nitrous oxide in patients with known ischaemic heart disease. In 20 patients who were due to undergo coronary artery bypass graft surgery, 30 min following induction of anaesthesia with fentanyl 30 microg x kg(-1) and midazolam 0.1 mg x kg(-1) but prior to the start of surgery, xenon or nitrous oxide 60% was administered for 15 min. The results showed that xenon caused a minimal decrease in the mean arterial pressure (from 81 (7) to 75 (8) mmHg, mean (SD)), but did not affect the systolic function of the left ventricle, as demonstrated by unchanged left ventricular stroke work index (LVSWI) and the fractional area change of the left ventricle (FAC) derived from transoesophageal echocardiography (TOE). However, in contrast, nitrous oxide was found to decrease the mean arterial pressure (from 81 (8) to 69 (7) mmHg), the LVSWI, and the FAC. The cardiac index, central venous and pulmonary artery occlusion pressures, systemic and pulmonary vascular resistances, and the TOE-derived E/A ratio through the mitral valve were unchanged by xenon or nitrous oxide. We conclude that xenon provides improved haemodynamic stability compared with nitrous oxide, conserving the left ventricular systolic function.
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PMID:Cardiovascular effects of xenon and nitrous oxide in patients during fentanyl-midazolam anaesthesia. 1554 76