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Query: UMLS:C0022116 (ischemia)
 91,303 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The origin of the vertebral artery is a frequent site for the development of stenosing lesions. The flow deficit caused by the stenosis of one vertebral artery is normally compensated for by intracranial anastomosis between the carotid and basilar arteries or by the opposite vertebral artery. A number of patients, however, have inadequate intracranial anastomosis and hypoplasia or stenosis of the opposite vertebral artery, and symptoms of brain ischemia develop. We describe here four cases in which a new technique, a subclavian vertebral artery autogenous vein bypass graft, was used to deal with the diseased segment of the vertebral artery. Transient postoperative problems included lymphocele and Horner syndrome. All four bypasses were patent at the time of angiography one week postoperatively. All four patients were relieved of symptoms of vertebrobasilar insufficiency.
Arch Surg 1976 Sep
PMID:Vertebral artery bypass. 94 61

Failure of glycolysis to increase sufficiently to supply optimal levels of energy production in ischemic heart muscle is due in part to the cummulative restrainst of acidosis on rate-limiting enzymes, particularly glyceraldehyde-3-phosphate dehydrogenase. In an effort to modify this inhibition and salvage jeopardized myocardium, treatment with excess levels of pyruvate and tromethamine (Tris), designed to buffer intracellular hydrogen ion accumulations and improve the oxidation-reduction ratio, NAD+/NADH, was tested in 59 swine hearts in two separate preparations of global and regional ischemia. Global ischemia, per se, caused hemodynamic deterioration and shortened survival time (44.3 +/- 3.1 minutes). Myocardial oxygen consumption, fatty acid oxidation, and glucose uptake were all significantly (P less than 0.001) reduced as were estimates of glycolysis and tissue stores of creatine phosphate and ATP (P less than 0.01). Although treatment with Tris alone was inconclusive, administrations of pyruvate (40-50 mM) buffered with Tris (added directly into the coronary perfusate) effected an improvement in mechanical function and a significant prolongation in survival time (56.9 +/- 2.6 minutes. P less than 0.01). Glycogenolysis was enhanced and levels of key glycolytic intermediates were reduced, suggesting an acceleration of glycolytic flux. Excess levels of pyruvate (1.52 +/- 0.48 mumol/ml of coronary perfusate) provided added substrate for oxidation and led to a greater than 5-fold incrase in rates of pyruvate decarboxylation as compared to untreated ischemic hearts...
Circ Res 1976 Sep
PMID:Effects of treatment with pyruvate and tromethamine in experimental myocardial ischemia. 95 68

Older people often describe their headaches as starting with vague neck discomfort and eventually moving to the temples and forehead. These are muscle-tension headaches, by far the most common type in the elderly. Although cervical osteoarthritis often is at fault, depression can be a significant factor, patricularly when headaches are chronic. There is no sure cure for tension headache, and often, several of the many remedies-ethyl chloride spray, moist heat, massage, antidepressant drugs, analgesics, local anesthetics, etc.-must be tried before an effective one is found. But just as important to successful therapy are concern, compassion, and a willingness to listen on the part of the physician. True migraine headaches are rare in the elderly. More prevalent is the type of vascular headache associated with giant cell arteritis, which is severe and resistant to any form of analgesic except the strongest narcotics. Vascular headaches also may result from congestive heart failure (which produces venous congestion in the cranial cavity), transient ischemia, increased intracranial pressure, and a variety of metabolic disturbances.
Geriatrics 1976 Sep
PMID:The types of headache that affect the elderly. 95 13

The hemodynamic determinants of the time-course of fall in isovolumic left ventricular pressure were assessed in isolated canine left ventricular preparations. Pressure fall was studied in isovolumic beats or during prolonged isovolumic diastole after ejection. Pressure fall was studied in isovolumic relaxation for isovolumic and ejecting beats (r less than or equal to 0.98) and was therefore characterized by a time constant, T. Higher heart rates shortened T slightly from 52.6 +/- 4.5 ms at 110/min to 48.2 +/- 6.0 ms at 160/min (P less than 0.01, n = 8). Higher ventricular volumes under isovolumic conditions resulted in higher peak left ventricular pressure but no significant change in T. T did shorten from 67.1 +/- 5.0 ms in isovolumic beats to 45.8 +/- 2.9 ms in the ejecting beats (P less than 0.001, n = 14). In the ejecting beats, peak systolic pressure was lower, and end-systolic volume smaller. To differentiate the effects of systolic shortening during ejection from those of lower systolic pressure and smaller end-systolic volume, beats with large end-diastolic volumes were compared to beats with smaller end-diastolic volumes. The beats with smaller end-diastolic volumes exhibited less shortening but similar end-systolic volumes and peak systolic pressure. T again shortened to a greater extent in the beats with greater systolic shortening. Calcium chloride and acetylstrophanthidin resulted in no significant change in T, but norepinephrine, which accelerates active relaxation, resulted in a significant shortening of T (65.6 +/- 13.4 vs. 46.3 +/- 7.0 ms, P less than 0.02). During recovery from ischemia, T increased significantly from 59.3 +/- 9.6 to 76.8 +/- 13.1 ms when compared with the preischemic control beat (P less than 0.05). Thus, the present studies show that the time-course of isovolumic pressure fall subsequent to maximum negative dP/dt is exponential, independent of systolic stress and end-systolic fiber length, and minimally dependent on heart rate. T may be an index of the activity of the active cardiac relaxing system and appears dependent on systolic fiber shortening.
J Clin Invest 1976 Sep
PMID:Hemodynamic determinants of the time-course of fall in canine left ventricular pressure. 95

Pre-eclampsia is characterized by uteroplacental ischemia. Prostaglandins can alter systemic blood pressure as well as regulate blood flow to the fetoplacental unit. In the present study, levels of prostaglandin E were significantly decreased in placental tissue from pre-eclamptic patients. Prostaglandin F, a potent vasoconstrictor, was markedly elevated. These observations indicate that altered placental metabolism of prostaglandins is an important factor in the pathophysiology of pre-eclampsia.
Am J Obstet Gynecol 1976 Sep 01
PMID:Placental prostaglandin levels in pre-eclampsia. 96 40

The effect of halothane on net myocardial oxygen balance of ischemic myocardium was studied in the non-failing canine heart. Myocardial ischemia was produced by repeated reversible occlusions of a coronary artery; the severity of ischemia was estimated by summating ST-segment elevations (sigma ST) obtained by epicardial ECG mapping at 15 to 18 sites. Control measurements were obtained before and after administration of halothane (0.75 per cent) to six dogs with chloralose-urethane basal anesthesia. Halothane was associated with significant decreases of systemic arterial pressure (P less than .001), heart rate (P less than .01), and the product of systolic arterial pressure X heart rate (P less than .01), an indirect index of myocardial oxygen consumption, while left atrial pressure remained unchanged at normal levels. sigmaST during occlusion was less (P less .001) during halothane (26.5 +/- 7.4 (SD) mv) than before (36.6 +/- 5.4 mv) or after (34.4 +/- 8.2 mv) its administration. Thus, halothane decreased the severity of experimentally-induced myocardial ischemia in the non-failing canine heart. The data suggest that, in the absence of ventricular failure, halothane influences the relationship between myocardial oxygen supply and demand in a favorable direction when coronary blood flow is limited.
Anesthesiology 1976 Sep
PMID:Halothane-induced decrease in experimental myocardial ischemia in the non-failing canine heart. 96 78

A constricting silicone band was added to 13% of local sponge buckle operations in this series. The purpose was to relieve circumferential traction or to maintain a high buckle. The inclusion of a cerclage did not require drainage of subretinal fluid. The rate of reattachment without drainage (42 of 50 detachments) is comparable to what might be expected if the subretinal fluid had been drained. Constriction was controlled and limited to between 10% and 25% of the circumference of the eye. Anterior segment ischemia requiring relaxation of the band occurred in two patients; scleral erosion did not occur.
Arch Ophthalmol 1976 Sep
PMID:Limits of constriction in the treatment of retinal detachment. 96 57

Previous studies on intact human subcutaneous tissue have shown, that blood flow remains constant during minor changes in perfusion pressure. This so-called autoregulatory response has not been demonstrable in isolated preparations of adipose tissue. In the present study on isolated, denervated subcutaneous tissue in female rabbits only 2 of 12 expts. revealed an autoregulatory response during reduction in arterial perfusion pressure. Effluent blood flow from the tissue in the control state was 15.5 ml/100 g-min (S.D. 6.4, n = 12) corresponding to slight vasodilatation of the exposed tissue. Following total ischemia all experiments showed a period with reactive hyperemia, and both duration of hyperemia and excess flow was related to the duration of the ischemia. This response therefore seems more resistant to the experimental procedure, while autoregulation of blood flow to lowered pressure is more susceptible to surgical exposure of the tissue. During elevation of arterial perfusion pressure blood flow in the isolated tissue showed a transient increase and then almost returned to the level during normotension, indicating an elevated vascular resistance. Raising of venous pressure elicited vasoconstriction with pronounced flow reduction. These two reactions may be important for local regulation of blood flow in subcutaneous tissue during orthostatic changes in arterial and venous pressure. It is concluded that the response in adipose tissue to changes in arterial pressure (autoregulation), venous pressure and total ischemia appear to be elicited by different mechanisms.
Acta Physiol Scand 1976 Sep
PMID:Intrinsic regulation of blood flow in adipose tissue. 97 Jan 54

From Wistar rats, data are presented which indicate that inbred females a) have a greater ability to clear particulate matter from the blood stream than do males of the same strain; b) are significantly more resistant to two different forms of lethal circulatory stress (e.g., intestinal ischemia and whole-body trauma) than are males; and c) exhibit a greater resistance to undergo reticuloendothelial system (RES) phagocytic depression after both forms of lethal trauma than do males. Estradiol treatment of males, using either acute, massive (1 or 10 mg/kg) or multiple, low dose (10 or 100 mug/kg) regimens, confers trauma resistance on such animals. Such estradiol treated male rats exhibit hyperactive RES's. These estradiol-treated males, when subjected to either lethal ischemia or trauma, fail to demonstrate the early RES phagocytic depression seen in untreated controls. Untreated female as well as estradiol-treated male rats exhibit significantly higher arterial blood pressures post-trauma than do untreated male rats. Direct microscopic observation of rat mesenteries indicr whole-b0dy trauma, the untreated females as well as the estradiol-treated males exhibit significantly less dilatation of microscopic capacitance vessels (i.e., venules) than do untreated male rats. The data reported herein could be used to suggest that estrogenic hormones may play pivotal roles in a) the amelioration of an organism's reaction to systemic stress; and b) control of macrophage and peripheral vascular functions.
Am J Physiol 1976 Sep
PMID:Sex and estrogens in protection against circulatory stress reactions. 97 Apr 65

The influence of temporary ischemia followed by recirculation on the ultrastructure of glomerular capillaries and some portions of the nephron was studied in 20 albino rats which were subjected to compression of the vascular bundle of the left kidney for 30 min., 1, 2 and 3 hours followed by recovery of the blood stream in the ischemic organ for 3 hours (with a simultaneous nephrectomy of the right kidney). The electron microscopic analysis has established that the amount of micropinocytic vesicles become markedly increased within 3 hours following 30-min. ischemia of the kidney with the recovery of blood circulation in the cytoplasm of endotheliocytes of glomerular blood capillaries. With increased terms of the left kidney ischemia (1, 2, 3 hs) the ultrastructural changes in endotheliocytes increased. There appeared microclasmatosis of the internal plasmalemma of endotheliocytes, the flattened peripheral part of the cytoplasm underwent considerable destruction. Swelling of microvilli of the brush border and vacuolization of the cytoplasm were observed in nephrocytes of the proximal part of the nephron in short-term ischemia (30 min) followed by the recovery of circulation for 3 hours. Longer periods of ischemia (1, 2, 3 hs) casued destruction of the brush border. There appeared secondary lysosomes, in mitochondria there occurred discomplexation and lysis of cristae.
Arkh Anat Gistol Embriol 1976 Sep
PMID:[Effect of temporary ischemia with subsequent recirculation on the ultrastructure of glomerular capillaries and nephrons]. 98 9


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