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Query: UMLS:C0038454 (stroke)
 147,016 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The present study was performed to document the relative efficacy of commonly applied techniques used adjunctively during 1 hour of descending thoracic aortic cross-clamping. Renal and cardiac responses were determined by standard laboratory methods. There were four experimental groups: (1) heparin-bonded shunt; (2) partial femoral-femoral bypass; (3) sodium nitroprusside; (4) control. Each of the experimental groups showed abnormal hemodynamic responses during cross-clamping. Elevations in left ventricular end-diastolic pressure (LVEDP) and systolic blood pressure were common events during clamping, and cardiac output often decreased. Nevertheless, left ventricular performance curves after cross-clamping showed similar increases in left ventricular stroke work (LVSW) with increasing preload. In addition, left ventricular biopsy specimens showed preservation of myocardial high-energy phosphate stores and essentially normal ultrastructural integrity. Radioactive microspheres generally showed increased myocardial blood flow during and after cross-clamping, but no evidence of preferential subendocardial ischemia. Examination of renal function showed a marked decrease in urine output, glomerular filtration rate, and renal plasma flow during cross-clamping. Following the release of the cross-clamp, renal function returned to 50% to 85% of baseline status. Since we could find no major advantage of any of the techniques employed under the present experimental conditions, we suggest that all of the techniques should be part of the surgical armamentarium and the particular preoperative and/or intraoperative findings in a specific case should determine which technique is most appropriate for a given patient.
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PMID:Cardiac and renal responses to cross-clamping of the descending thoracic aorta. 663 46

31P NMR technique was applied to monitor changes in the energy metabolism of the brain and heart of unanesthetized cats during shock, stroke, hypoxia and increased functional activity. The results show that in these tissues content of inorganic phosphate, sugar phosphates, phosphocreatine and of ATP can be measured decently in awake animals. At the same time this technique has the great advantage over the disruptive biochemical methods that it gives a semi-continuous reading and it is non-invasive. Our findings are summarized as follows: Hemorrhagic shock resulted in an irreversible deterioration of the energy state of the brain. Our stroke model led to a very marked increase in Pi and a decrease CP in the brain but these changes were reversible. The ATP levels of the brain as it was indicated by 31p NMR spectra were not affected by hemorrhagic shock and stroke which can be attributed probably by the reduced rate of ATP consumption. The verification of this hypothesis needs further work. During increased mechanical performance the levels of SP, and Pi increased, ATP decreased, while CP was not influenced in the heart.
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PMID:31P NMR spectroscopy of brain and heart. 663 19

The acute metabolic and hemodynamic effects of dopamine, dobutamine (both at 10 micrograms . kg-1 . min), and isoproterenol (at 0.05 or 0.1 micrograms . kg-1. min) were determined in dogs following 20 minutes of normothermic global myocardial ischemia. The catecholamines were started 10 minutes before cardiopulmonary bypass (CPB) was discontinued and were continued for 1 hour after bypass. Regional myocardial and systemic blood flow distribution was measured by means of the radioactive microsphere technique. On bypass all catecholamines sharply increased heart rate, myocardial oxygen consumption, and left ventricular blood flow (p less than 0.01). Because the hearts were unloaded, these data suggest that velocity of contraction is an important component of myocardial oxygen consumption. Although these drugs did not lower myocardial adenosine triphosphate (ATP) and creatine phosphate (CP) levels, the significant rise in oxygen consumption suggested that inotropic treatment on bypass may not be beneficial. Furthermore, renal blood flow was diminished in dobutamine-treated dogs (p less than 0.01) and tended to decrease with isoproterenol infusion. No change was seen with dopamine infusion. After bypass, dobutamine treatment increased cardiac output (p less than 0.01) and stroke volume (p = 0.017) with no change in heart rate, myocardial oxygen consumption, high-energy phosphate levels, and total or transmural distribution of left ventricular blood flow. Dopamine infusion did not change cardiac output but did increase oxygen consumption (p less than 0.01). Isoproterenol showed a slight inotropic effect, but frequent ventricular arrhythmias were present during weaning from bypass. In all treatment groups, blood flow in the other systemic beds (cerebral, gastrointestinal, and renal) was similar to that in control dogs. These data suggest that dobutamine is the most efficient of the drugs tested for support of the heart following global myocardial ischemia but, when given during bypass, it appears to decrease renal blood flow.
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PMID:Comparison of catecholamine effects on canine myocardial metabolism and regional blood flow during and after cardiopulmonary bypass. 670 Feb 52

To determine the myocardial temperature that provides maximal preservation of the heart during global ischemic arrest, five groups of dogs were studied (6 per group). In all animals, the aorta was cross-clamped for 120 minutes. Serial biopsies were done for determination of adenosine triphosphate and creatine phosphate, and study by electron microscopy. Starling curves were derived prior to cardiopulmonary bypass and 60 minutes after bypass. Mitochondrial changes were graded on a scale of 0 to 4. In the control group (Group 1), the aorta was clamped when the rectal temperature reached 25 degrees C (myocardial temperature, 18 degrees to 22 degrees C). In Groups 2, 3, 4, and 5, myocardial temperature was maintained at 6 degrees C, 10 degrees C, 14 degrees C, and 18 degrees C (all +/- 2 degrees C), respectively, by the use of systemic and topical hypothermia and repeated injections of cold cardioplegic solution into the aortic root. All groups showed a depression of left ventricular stroke work index, particularly Group 1 (no survivors), Group 2, and Group 3. The high-energy phosphate stores were well preserved in all groups except Group 1. The mitochondrial ultrastructure showed significant changes in all groups, especially Groups 1 and 5. These data indicate that satisfactory preservation of mitochondrial ultrastructure and high-energy phosphates was achieved at myocardial temperatures lower than 18 degrees C. Extreme hypothermia (Groups 2 and 3) was associated with significant reduction in ventricular function under the experimental conditions employed.
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PMID:The optimal temperature for preservation of the myocardium during global ischemia. 686 4

Phosphorus nuclear magnetic resonance with surface coils was used to investigate the regional metabolism of the rat brain in vivo under conditions of normoxia, severe hypoxemia, partial necrosis, and partial ischemia. The results show an increase in sugar phosphate and/or inorganic phosphate with injury in accordance with in vivo assays. The technique provides a powerful means of monitoring the metabolism of stroke and its response to therapy in vivo.
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PMID:Cerebral energy metabolism in rats studied by phosphorus nuclear magnetic resonance using surface coils. 692 98

Aspartate aminotransferase (EC 2.6.1.1:AST) is known to have two isoenzymes, one associated with the cytoplasm (c-AST) and the other with the mitochondria (m-AST). We studied the relationships of m-AST activity in the coronary sinus blood to left ventricular function, coronary blood flow, water content and high-energy phosphate stores of the left ventricle following hypothermic ischemic cardiac arrest. Under cardiopulmonary bypass with hypothermia of 20 degrees C of myocardial temperature, 120 min of aortic occlusion was employed in 15 mongrel dogs. Left ventricular function (peak left ventricular pressure, left ventricular end-diastolic pressure, max dp/dt, cardiac index, left ventricular stroke work index), coronary blood flow, myocardial oxygen consumption, myocardial enzyme activity (m-AST, CK-MB), myocardial water content and high-energy phosphate stores (adenosine triphosphate, creatine phosphate) of the subendocardium of the left ventricle were measured. Data was obtained in the control state, and after 0, 30 and 60 min of reperfusion. Significant negative correlations were obtained between m-AST activity and peak left ventricular pressure (r = -0.81, p less than 0.001), max dp/dt (r = -0.83, p less than 0.001), cardiac product (r = -0.73, p less than 0.01), coronary blood flow (r = -0.59, p less than 0.05), adenosine triphosphate level (r = 0.72, p less than 0.01) and creatine phosphate level (r = -0.72, p less than 0.02) after 60 min of reperfusion. Significant positive correlations were obtained between m-AST activity and left ventricular end-diastolic pressure (r=0.75, p less than 0.01) and water content (r = 0.78, p less than 0.01) after 60 min of reperfusion. These results led to the assumption that serum m-AST activity in the coronary venous blood is a useful index to evaluate the degree of myocardial injury.
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PMID:Studies on the significance of serum mitochondrial aspartate aminotransferase activity following ischemic cardiac arrest. 714 3

The hemodynamic effects of disopyramide phosphate, 2.0 mg/kg body weight, given intravenously over a period of five minutes were studied at rest and during exercise in ten patients without clinical or angiographic evidence of heart disease. Following disopyramide, the resting cardiac index was lower (4.0 +/- 0.6 vs 4.3 +/- 0.6 liters/min/m2, mean +/- 1 SD,P less than 0.05), while left ventricular end-diastolic pressure (16 +/- 4 vs 11 +/- 4 mm Hg, P less than 0.001), pulmonary arterial (PA) mean pressure (20 +/- 5 vs 17 +/- 5 mm Hg, P less than 0.05), and brachial arterial (BA) mean pressure (105 +/- 8 vs 96 +/- 7 mm Hg, P less than 0.05), were higher than the pre-infusion resting values. During exercise, there was no change in left ventricular end-diastolic pressure while cardiac index rose from 4.0 +/- 0.6 to 6.5 +/- 0.6 liters/min/m2 (P less than 0.001) and left ventricular stroke work index increased from 62 +/- 19 to 84 +/- 22 gm/beat/m2 (P less than 0.001). The normal hemodynamic response during exercise after disopyramide despite the apparent depression of left ventricular function at rest probably reflects the positive inotropic effect of enhanced sympathoadrenergic activity.
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PMID:Hemodynamic effects of disopyramide at rest and during exercise in normal subjects. 721 18

A retrospective study was made of 111 patients who underwent computed tomography (CT) and nuclear brain scans, with both pertechnetate and phosphate bone agents (PHOS), within 7 days of each other. Specifically, 78 patients who had a recent cerebral vascular accident (CVA) were compared. There were no significant sensitivity differences between the methods. While these studies appear complementary, the most important criterion is the time after onset when the studies were performed. The axiom "if the intensity of the phosphate scan exceeds that of the pertechnetate, the lesion must be a CVA" is true, only if the study is performed within 4 weeks of onset. The most economical method for optimum detection of CVA, with avoidance of frequent errors, is an early CT followed by a PHOS brain scan about 14 days after ictus in those that have initial negative CT.
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PMID:Comparison of CVA imaging with 99mTc phosphates, 99mTc pertechnetate, and computed tomography. 725 16

The effects of intravenous disopyramide phosphate on myocardial function were evaluated by non-invasive indices of cardiac performance (systolic time intervals, STI) in 15 patients with atherosclerotic heart disease and different degrees of cardiac failure. Disopyramide (1.5 mg/Kg) was given intravenously over a period of 5 min. This drug induced in patients in I-II classes of NYHA a significant decrease of LVETc, while PEP, ICT, and PEP/LVET ratio rose significantly. STI were affected much more markedly in patients in III-IV classes of NYHA. Particularly affected were contractility indices (PEP, ICT, PEP/LVET), which were reduced significantly more in patients in III-IV classes as compares to patient in I-II classes. In contrast, LVETc, which correlates to stroke volume and cardiac output, was similarly worsened by the drug in the 2 groups of patients. Therefore, this study shows that disopyramide has relevant depressant effects on myocardial performance, simultaneously reducing stroke volume and contractility, and that the effect on contractility is more marked in patients with severe left ventricular impairment.
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PMID:Effects of intravenous disopyramide on myocardial function in patients with different degrees of cardiac failure. 737 60

The hemodynamic effects of disopyramide phosphate were studied in nine patients with left ventricular dysfunction. After control measurements, administration of a 2 mg/kg bolus of disopyramide phosphate over 5 or 15 minutes was followed by a 20 minute 0.4 mg/kg/hour infusion and a 15 minute recovery period. Response to the 5 and 15 minute bolus injection was similar. Maximum hemodynamic effects occurred immediately after the bolus was given; there were decrements in systolic pressure (142 to 124 mm Hg)(p less than 0.005), cardiac index (2.5 to 1.8 liters/min/m2)(p less than 0.001) and stroke index (29.4 to 20.6 ml/beat/m2)(p less than 0.001), and increases in right atrial pressure (9 to 12 mm Hg)(p less than 0.005) and total peripheral resistance (21.2 to 25.7 U)(p less than 0.005). Two studies had to be terminated after the bolus was given due to profound hemodynamic deterioration. In the remainder, the systolic pressure returned to control by the end of the infusion, whereas the mean arterial pressure increasd significantly (92 to 96 mm Hg)(p less than 0.01). Little further change in mean arterial pressure, cardiac and stroke index, and total peripheral resistance occurred during the recovery period. These data indicated that intravenous disopyramide phosphate is a potent cardiac depressant when given over 5 to 15 minutes to patients with left ventricular dysfunction. It is concluded that disopyramide should not be administered to such patients unless conventional therapy fails. In such circumstances it should be used with extreme caution and careful monitoring.
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PMID:Cardiac depression by intravenous disopyramide in patients with left ventricular dysfunction. 738 91


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