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

The mitochondrial fraction obtained from brains of animals submitted to ischemia shows a decrease of phospholipid level, especially plasmalogens in the fraction of ethanolamine phospholipids and choline phospholipids. There appears simultaneously an increase of free radical oxidation processes of unsaturated fatty acids from these phospholipids. The peroxidation processes of mitochondrial lipids are stimulated by calcium ions and, to a smaller extent, by magnesium ions. Barbiturate anesthesia inhibits the peroxidation of fatty acids and increases the antioxidant abilities of the nervous tissue. Nembutal added in vitro remains without effect on the above processes. The effect of acetylcholine and the antioxidant ability of nervous tissue under barbiturate anesthesia with respect to ischemia are discussed.
Brain Res 1978 Dec 15
PMID:Effect of ischemic anoxia and barbiturate anesthesia on free radical oxidation of mitochondrial phospholipids. 70 72

We studied the role of cardiopulmonary vagal afferents in the cardiovascular responses to coronary artery occlusion in conscious dogs with intact carotid sinuses and following functional denervation of the arterial baroreceptors. The contributions of vagal afferents were determined by cold blocking the vagi. In dogs with intact carotid sinuses, coronary artery occlusion produced small decreases in mean cardiac output and arterial pressure, whereas heart rate increased by 35 beats/min. In dogs with intact carotid sinuses, vagal cold block increased mean arterial pressure by 22 +/- 2 (mean +/- SE) mm Hg and heart rate by 90 +/- 6 beats/min. Mean cardiac output increased by 505 +/- 90 ml/min. With the exception of heart rate, responses to coronary occlusion during vagal cold block were similar to the occlusion response prior to vagal cold block. Furthermore, prior occlusion of the coronary artery did not significantly influence the responses to vagal cold block. After arterial baroreceptor denervation, coronary artery occlusion resulted in a substantially greater fall in systemic arterial pressure (-52 mm Hg as compared to -8 mm Hg, with intact carotid sinuses) and peripheral resistance decreased by -0.49 peripheral resistance units (PRU). Vagal cold block following denervation increased the arterial pressure by 49 +/- 10 mm Hg and peripheral resistance by 0.59 +/- 0.13 PRU. Both values were significantly greater than those observed during vagal cold block prior to denervation. In arterial baroreceptor-denervated dogs, vagal blockade significantly attenuated the response to coronary occlusion. Therefore, in conscious dogs, vagal afferents from cardiopulmonary receptors exert a significant inhibitory influence on the peripheral vascular tone. When the carotid sinuses are intact, this inhibitory influence appears to be marked during myocardial ischemia. In the absence of functional arterial baroreflexes, vagal afferent activity contributes to the depressor responses observed during ischemia.
Circ Res 1978 Dec
PMID:The circulatory influences of vagal afferents at rest and during coronary occlusion in conscious dogs. 70 45

The solid angle theory has long been applied to the interpretation of the ECG; however, quantitative evaluation of its applicability has been minimal. We applied solid angle analysis to the interpretation of the TQ-ST deflection during acute ischemia. Five anesthetized pigs were studied 1--3 hours after coronary occlusion. Multiple unipolar tracings were recorded from precisely determined positions on the epicardium overlying the ischemic and normal zones. The geometry of the hearts and ischemic zones was preserved, the margins of ischemia being defined as the outer border of Thioflavin S nonfluorescence. Wax replicas of the hearts with ischemic zones removed were constructed. Solid angles subtended at electrode positions on the replicas were calculated. A linear relationship (r = 0.84 - 0.97, P less than 0.001) was shown to exist between the observed TQ-ST deflection and the calculated solid angle. A small but patterned deviation from exact fit of the TQ-ST deflection with the calculated solid angle led us to investigate the possibility that dipole moment strength (phi) is not confined to the ischemic margins. Computations using idealized heart models with ischemic zones cylindrical and transmural in shape allowed us to distribute phi arbitrarily within the ischemic zone, comparing this predicted pattern of TQ-ST deflection with that observed experimentally. The experimental data appear most consistent with the condition in which phi is distributed over a 1-cm border region during the first several hours of ischemia. We conclude that the solid angle theory provides a rational basis for interpretation of the ischemic TQ-ST deflection; however, phi may be distributed over a marginal zone.
Circ Res 1978 Dec
PMID:A solid angle analysis of the epicardial ischemic TQ-ST deflection in the pig. A theoretical and experimental study. 70 50

Experimental work has shown that even small reductions in myocardial perfusion impair contractile performance. We, therefore, studied the relationship between regional perfusion, assessed by thallium-201 scintigraphy and segmental wall motion, quantitated on biplane contrast ventriculograms, in patients with coronary artery disease. We evaluated 270 segments in 54 patients, including 27 without evidence of myocardial infarction. Most normally perfused regions (125 of 140) contracted normally, whereas those with scintigraphic defects at rest were usually asynergic (42 of 46). Surprisingly, 57% (48 of 84) of regions with exercise-induced perfusion defects were also asynergic, including 48% (25 of 52) of those in patients without myocardial infarction. In 22 patients who had intervention ventriculograms, improvement of perfusion abnormalities at rest correlated closely with reversibility of asynergy. Although there was an association between the location and severity of coronary artery stenosis and segmental wall motion, myocardial perfusion during exercise was a significantly better predictor of asynergy. These findings suggest that resting asynergy may occur even in patients without previous infarction, predominantly in regions with jeopardized perfusion. Asynergy in regions with exercise-induced perfusion abnormalities may, therefore, be an indicator of resting ischemia and may be reversible by coronary artery revascularization.
Circulation 1978 Dec
PMID:Relationship of regional myocardial perfusion to segmental wall motion: a physiologic basis for understanding the presence and reversibility of asynergy. 70 71

Emergency revascularization for unstable angina (defined according to criteria of the National Cooperative Study Group) was performed in 100 consecutive patients. The mean interval from onset of pain to operation was one day. Nineteen patients had single-vessel narrowing of greater than 70% of lumen diameter, 32 double-vessel obstruction and 49 triple-vessel disease. Fourteen of these patients had left main trunk obstruction. Four patients died within 30 days, three from complications of myocardial infarction. Seventeen of 96 (18%) early survivors sustained perioperative infarction. After a mean follow-up of 42 months, four late deaths and three late infarctions occurred. Postoperative angiography in 47 patients (mean interval 14 months) showed 86% graft patency. Of 92 survivors, 72 are symptom-free. Three of the four operative deaths occurred within 24 hours postoperatively; in each of these, postmortem examination confirmed a recent myocardial infarction which antedated the operation, despite the absence of new infarction in the peroperative electrocardiogram or elevation of cardiac enzymes. Results from this emergency series suggest that, although myocardium may be salvaged in some instances, in other cases infarction has already occurred and treatment might better be directed toward alleviation of acute ischemia to provide a stable period in which diagnostic studies are performed and acute myocardial infarction may be ruled out.
Circulation 1978 Dec
PMID:Emergency revascularization for unstable angina. 70 72

Bile salts, mechanical trauma, and ischemia were used to produce focal alterations in rat gastric mucosa in a chamber preparation. Gastric mucosal to serosal potential difference (PD) was measured from both treated and untreated areas using electrodes in contact with the mucosal surface. The sensitivity of the measurements was increased if a nonconducting solution (isotonic sucrose) was used to isolate electrically the control from the experimental sites. This "sucrose gap" technique thus allows the identification of focal areas of gastric mucosa with an altered PD. In addition, this technique was used to measure the PD of the forestomach, fundus, and antrum of the rat, and to demonstrate that atropine and pentagastrin influence the PD only in the fundus.
Gastroenterology 1978 Dec
PMID:"Sucrose gap" technique for measurement of focal gastric mucosal potential differences in the rat. 71 Aug 64

Because arteriosclerotic popliteal aneurysms so often present with complications, treatment results are less than optimal in contrast to aneurysms oat other sites. From 1963 to 1977, 40 surgically treated aneurysms in 30 patients were studied. Seventeen limbs presented as asymptomatic aneurysms (42.5%), four with pressure symptoms (10%), one with rupture and ischemia (2.5%), nine with acute thromboses and ischemia (22.5%), and nine with chronic ischemia and claudication (22.5%). Seventeen aneurysms were thrombosed (42.5%). Diameters of all aneurysms measured at operation ranged from 1.0 to 10 cm. It was of interest to note that, generally, larger aneurysms were patent, and thromboses were common in the smaller aneurysms, with an average diameter of 2.5 cm. Saphenous vein grafts were used most frequently for interpolation grafts (65%) and bypass grafts (12.5(). Prosthesis were used in 7.5%, endarterectomy and aneurysmorraphy in 5%. Popliteal reconstruction was accomplished initially in 40 limbs, with two early failures and 10 late failures with loss of two limbs. Cumulative patency rates for 40 limbs at risk at 5 and 10 years were 75.9%, at 14 years, 62.6%. Diagnosis is the most difficult aspect of this problem, as physical limitations impede early diagnosis. Thromboses being the natural history of popliteal aneurysms, early recognition and treatment are important to improve limb salvage rates.
Surgery 1978 Dec
PMID:Complications and treatment of popliteal aneurysms. 71 97

Despite a general impression to the contrary, a recent survey showed that the current mortality rate for acute arterial ischemia approximates 25%. Much of this apparently relates to toxins and procoagulants released from the dying limb, a tendency which may be enhanced further by attempts at revascularization. Based on these observations, we have utilized selective management of acute arterial ischemia in an attempt to minimize deaths and to salvage the maximum number of limbs. If the patient presents within 6 to 8 hours of the onset of acute arterial occlusion and if paralysis or anesthesia is present, then ultimate limb loss is likely. The therapeutic choices are high-dose heparin therapy, operative removal of the clot, or amputation of the limb--the ultimate choice being dependent upon the particular status of the patient. But if sensation and motor function are present, viability of the limb is not threatened, and good results can be obtained by utilizing anticoagulation and delayed elective revascularization, if the latter is indicated. But revascularization attempts after 10 to 12 hours of severe ischemia often are unsuccessful, and ischemia is followed by either recurrent thrombosis and ultimate limb loss, or by death from the systemic effects of reperfusion of ischemic tissue. This type of limb is managed best by using high-dose heparin therapy if viable, or by amputation if it is not. Employing the above criteria, 54 patients with acute arterial ischemia averaging 59 years of age, were treated. Seventeen had immediate thrombectomy, yielding two deaths and four subsequent amputations. Twenty-nine received anticoagulation treatment, resulting in one death and five amputations, and six had immediate amputation, yielding one death. Three had no specific treatment, with one poor result. There were four deaths in the entire series--a mortality rate of 7.5%--and two thirds of the limbs were salvaged. We have concluded that selective management, as prescribed above, was responsible for a significant decrease in mortality rate with no corresponding increase in limb loss, and that high-dose heparin therapy ultimately may prove the initial treatment of choice in all cases of acute arterial ischemia.
Surgery 1978 Dec
PMID:Management of acute lower extremity arterial ischemia due to embolism and thrombosis. 71 1

Spinal cord blood flow (SCBF) was measured in 12 albino rats following acute cord injury produced by the extradural clip compression technique. Severe injury was produced with the clip compressing the cord with a force of 180 gm for 5 minutes, an injury previously shown to produce a severe functional deficit. Regional SCBF was measured 15 minutes, 2 hours, and 24 hours after injury by the 14C-antipyrine autoradiographic technique and a scanning microscope photometer. At 15 minutes and 2 hours, white and gray matter blood flow was severely diminished, and, at 24 hours, there was only minimal improvement. Focal decreases in blood flow were seen in white and gray matter for a considerable distance proximal and distal to the site of cord trauma. Thus, it has been confirmed in this model that severe cord compression injury produces severe posttraumatic ischemia in the cord which lasts for at least 24 hours.
J Neurosurg 1978 Dec
PMID:Regional spinal cord blood flow in rats after severe cord trauma. 73 1

Serial renography with [125I]-o-iodohippurate was performed in 42 rabbits after temporary clamping of the renal artery for 1--3 hr and contralateral nephrectomy. Renograms were done before and after warm ischemia and followed 2, 4, 6, and 14 days after restoration of circulation. Correlation was found between duration of ischemia and severity of postischemic renographic changes. Most sensitive was the third phase, which showed distortion after 1 hr of ischemia; the second phase decreased after 2 1/2 hours of ischemia. The profound changes seen on the second day were shown to be due to further damage of the tubular cell system after restored flow. In vitro [125I]-o-iodohippurate uptake in cortex slices showed a significant decrease after warm ischemia damage and 48 hours restored flow. The second phase recovered more rapidly than the excretory function.
J Nucl Med 1978 Dec
PMID:Sequential [125I]-o-iodohippurate renograms from rabbit kidneys after temporary renal ischemia. 73 19


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