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

Hearts with one underdeveloped and one dominant ventricle form a spectrum of anomalies extending from the heart with two clearly adequate chambers to those with a true single ventricle. An angiographic concept of grouping such hearts is presented. 129 patients with unequal ventricles underwent catheterization and cineangiography between 1974 and 1983. The age at first catheterization ranged from one day to 24 years (mean 3.9 years). Male-female ratio was 2:1. Five groups of hearts (with their relative frequencies in the spectrum) were established: dominant left ventricle (53%); dominant right ventricle (20%), each with normally related chambers; dominant left ventricle (20%); dominant right ventricle (3%), each with ventricular inversion; true single ventricle (5%). The incidence of atrial anatomy, venous return, intracardiac connections and associated lesions within each group was assessed. From the standpoint of deranged physiology as well as surgical implications there are more similarities than differences among these hearts. The fact that one ventricle will not generate an adequate stroke volume after repair is overwhelmingly more important than most other considerations. For the diagnostic and surgical approach, we believe that the system offers many advantages.
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PMID:Spectrum of hearts with one underdeveloped and one dominant ventricle. 380 91

Isolated pumping rat hearts, perfused with reconstituted blood, were studied to compare the effects of 30 minutes of ischemic arrest following calcium-free or normal, calcium-containing cold cardioplegia on recovery of mechanical function, lactate production, myocardial adenosine triphosphate concentration, and release of creatine kinase (CK). As in clinical situations, the volume of the infusate was only three to four times the intracavitary blood volume. Hearts arrested with calcium-free solution showed incomplete recovery of mechanical function, whereas hearts arrested with calcium-containing solution recovered completely. After calcium-free arrest, stroke volume recovered to 76 +/- 29% (standard deviation [SD]) of its prearrest value. Enzyme release (CK) was significantly higher after calcium-free cardioplegia (7.7 +/- 4.6 units [SD]) than after cardioplegia with normal calcium (2.1 +/- 1.6 units [SD]). Since the addition of only 0.025 mmol calcium ions to a liter of calcium-free solution completely prevented its negative effect, it was concluded that calcium-free cardioplegia may cause limited but pronounced damage to myocardial cells, presumably because it removes calcium from the cellular membranes--the so-called calcium paradox. Probably due to residual calcium in blood and extracellular fluid, the damage is not so extensive after calcium-free cardioplegia as to be noticeable in clinical surgical situations. Residual calcium in the heart does not exclude the possibility, however, that a calcium paradox occurs in small scattered areas of the heart.
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PMID:Cold ischemic arrest: comparison of calcium-free and calcium-containing solutions. 392 Sep 84

Experiments were conducted to determine whether chronic caffeine consumption during early growth and development affected cardiac performance and development of adipose tissue. Dams were fed a nutritionally complete diet with or without the addition of 10 mg/kg caffeine during lactation. After weaning, the pups were maintained on this diet until they were sacrificed at 88 days of age. Body weight at the time of sacrifice was comparable for both groups. The hearts from caffeine-fed animals were significantly (P less than 0.05) larger based on both dry and wet weights although the dry weight/wet weight ratios were similar. Ventricular function curves were generated on each heart using an isolated working heart preparation. The isolated hearts of caffeine-fed rats exhibited a significant reduction in cardiac output, stroke volume, mean aortic pressure, and estimated myocardial work when compared to controls. The rats fed caffeine had greater plasma triglyceride levels with no significant differences in adipocyte size or number in the epididymal and perirenal depots. It is concluded that chronic caffeine intake from birth may alter cardiac function of the offspring.
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PMID:Effects of chronic caffeine ingestion on growth and myocardial function. 400 Nov 33

The efficacy of moderate hypothermia with rewarming in attenuating the myocardial and circulatory consequences of acute coronary ligation was studied in open-chest, anesthetized dogs. Thirty minutes after ligation of the proximal left anterior descending coronary artery, 14 dogs were surface-cooled to 27 degrees C, maintained at this temperature for 2 hr, rewarmed to normothermic levels, and monitored for an additional hour. Fifteen dogs were maintained for a corresponding time period after coronary ligation at normothermic levels. Dogs maintained normothermic demonstrated significant depression (from preligation values) of dP/dt, cardiac output (CO), stroke volume (SV), and left ventricular stroke work and power (LVSW, LVSP) at elevated levels of left ventricular end-diastolic pressure (LVEDP). Dogs subjected to the hypothermic procedure demonstrated decreased inotropic status during hypothermia, but with rewarming, exhibited significantly greater values of left ventricular pressure, dP/dt, CO, SV, LVSW, and LVSP at lower values of LVEDP than observed in dogs maintained normothermic. Increased dysrhythmic activity was not observed during hypothermia. Hearts from dogs subjected to the hypothermic protocol demonstrated qualitatively greater dehydrogenase activity both at the periphery and in the center of the nonperfused region. The results suggest that moderate hypothermia during evolving myocardial infarction may preserve left ventricular cardio- and hemodynamics and thus may be useful in delaying morphological and functional deterioration until definitive treatment can be instituted.
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PMID:Salutary effects of moderate hypothermia on the circulatory and myocardial consequences of acute coronary occlusion in dogs. 407 11

The purpose of the present study was to determine if contractile function adapts to physical training in the same way in hearts of male and female rats. Male and female rats were trained with a running program sufficient to cause equal increases in cytochrome oxidase activity in gastrocnemius muscles in both groups. Hearts were then studied in an isolated perfused working rat heart apparatus with varying preloads and fixed afterloads. Five groups were studied: 1) free-eating sedentary males (MS-FE); 2) running males (MR); 3) sedentary females (FS); 4) running females (FR); and 5) food-restricted sedentary; males (MS-FR). Heart weights were similar in MS-FE and MR and in FS, FR, and MS-Fr. Stroke work, stroke volume, coronary flow, and myocardial oxygen consumption were significantly higher in MR than in MS-FE but were almost identical in FR and FS. MS-FR showed stroke work, stroke volume, and ejection fractions that were similar to MR but higher than MS-FE and both female groups. Thus when hearts of equal weights were compared, a training effect was only seen in males. These results suggest that despite similar skeletal muscle adaptations, hearts of male rats adapt to physical training by running with improved intrinsic performance, whereas hearts of female rats do not.
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PMID:Cardiac responses to exercise training in male and female rats. 625 97

Hearts of rats made hypertensive (BP greater than 150 mmHg) by left renal artery clipping and sham operated controls were studied in two series of experiments. In series I, cardiac function was studied in an isolated working heart apparatus at weeks 4, 9 to 10 and 16 to 17 post-surgery. In series II, coronary flow was studied during normoxic and anoxic retrograde perfusions at days 6 to 9 and at weeks 4 and 10 post-surgery. In series I, when compared with controls, hypertensives had lower body weights at weeks 4 and 9 to 10, and higher left ventricular weights at each period. Heart function was depressed for hypertensives when compared with controls as measured by lower stroke volume, peak left ventricular systolic pressure, stroke work, ejection fraction, positive dP/dt, peak aortic flow, and maximal flow acceleration. Relaxation rate as measured by negative dP/dt was also depressed. Hearts from hypertensives had significantly lower coronary flows and MVO2, and increased percent oxygen extraction and effluent lactate/pyruvate ratios. LVEDP was significantly elevated for hypertensives, when LVEDV (ml) was similar for hypertensives and controls. Myocardial actomyosin ATPase activity was depressed for hypertensives at weeks 9 to 10 and 16 to 17 post-surgery. In series II, when hearts were perfused retrogradely, coronary flow was lower for hypertensives than for controls during normoxia at days 6 to 9 and at week 4, and during anoxia at all time periods. The findings demonstrate that impaired coronary vascular reserve develops within days of the development of hypertension in rats, and this can be associated with impaired ventricular function.
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PMID:Impaired coronary flow and ventricular function in hearts of hypertensive rats. 662 76

Compared with isolated heart muscle and Langendorff preparations, the isolated, working heart preparation allows a more complete analysis of cardiac function and metabolism. We have studied the effects of amrinone 20 micrograms/ml and 200 micrograms/ml on the isolated perfused working guinea-pig heart. We have measured: heart rate (HR), mean systolic aortic pressure (SP), aortic flow (AF), coronary flow (CF), total cardiac output (CO), and calculated the stroke volume (SV) and the rate of external work (W). The rates of oxygen consumption (VO2) and lactate production (Lact) were also measured and the external efficiency (Eff) calculated. Hearts were allowed to fail spontaneously after work for 90 min. Amrinone was then added at the required concentration to the perfusion medium. Amrinone 20 micrograms/ml, increased AF, CF, CO, SV, W and VO2. HR was slightly but significantly increased. Lact and Eff were not altered. Amrinone 200 micrograms/ml substantially increased CF and VO2, but it increased slightly and not significantly AF, CO, SV and W, suggesting the predominance of the coronary vasodilating effect of amrinone at higher doses. Lact and Eff remained unchanged. The positive chronotropic effect was of the same magnitude than that observed with the lower dose. No arrhythmias occurred with either concentration. These results would suggest that amrinone is a positive inotropic drug with vasodilating properties at higher doses, and weak positive chronotropic effect. It stimulates aerobic but not anaerobic metabolism of the heart.
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PMID:The effects of amrinone on cardiac function, oxygen consumption and lactate production of an isolated, perfused, working guinea-pig heart. 688 99

To explore the effects of diabetes on myocardial function and metabolism we injected male rats with streptozotocin and studied their hearts 8 weeks later. Blood sugar levels in the treated rats were about 600 mg/100 ml. Body and heart growth rates were diminished. When studied in an isolated working rat heart apparatus using 5.5 mM glucose, hearts of diabetic animals showed diminished cardiac output and stroke work at high filling pressures. There also were significant depressions in peak left ventricular systolic pressure, peak aortic flow rate, maximum negative dP/dt, myocardial oxygen extraction, myocardial lactate production, and effluent lactate:pyruvate ratios. Myocardial glycogen stores, calculated glycogen utilization, and pyruvate production were increased in hearts of diabetics, and myocardial oxygen consumption was the same as in control hearts. The end-diastolic pressure-volume relationship was shifted to the right in hearts of diabetics. Most of the abnormalities observed in hearts of diabetic rats persisted when insulin and 15 mM glucose were included in the perfusion medium. Hearts from young rats or from age-matched food-restricted rats with heart weights similar to those of diabetics did not show depressed function or a pressure-volume shift. Our findings indicate that streptozotocin diabetes in rats results in abnormal myocardial performance. This is not due to restrictions in coronary flow or myocardial oxygenation and is not correctable by the provision of high glucose plus insulin in the perfusion medium.
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PMID:The effect of diabetes on performance and metabolism of rat hearts. 700 45

The deleterious effect of hyperkalemic cardioplegic solutions on coronary endothelium has been documented and has also been demonstrated with University of Wisconsin solution. We evaluated a new extracellular University of Wisconsin formulation for efficacy in heart preservation. Six neonatal piglet hearts were arrested with and stored in the standard intracellular University of Wisconsin solution (group 1: K+ 125 mEq/L, Na+ 29 mEq/L). Six piglet hearts were preserved for 24 hours with an extracellular University of Wisconsin solution that differed only in the concentrations of potassium and sodium (group 2: K+ 25 mEq/L, Na+ 129 mEq/L). Hearts underwent modified reperfusion with leukocyte-depleted aspartate-glutamate enriched blood cardioplegic solution followed by conversion to a left-sided working mode on a Langendorff circuit with perfusion from a support pig. Stroke work index was calculated at left ventricular end-diastolic pressures of 3, 6, 9, and 12 mm Hg. Sixty minutes after reperfusion, there was no significant difference in stroke work index between group 1 (16.4 +/- 1.9 x 1000 erg/gm) and group 2 (15.3 +/- 2.7 x 1000 erg/gm). There was also no significant difference in high-energy phosphate stores or myocardial water content between the two groups. Extracellular University of Wisconsin solution provides myocardial preservation equivalent to standard University of Wisconsin solution while preventing exposure of coronary endothelium to high levels of potassium, which justifies its use in clinical heart transplantation.
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PMID:Extracellular and standard University of Wisconsin solutions provide equivalent preservation of myocardial function. 756 41

The primary objective of this study was to compare the protective effects of single-dose and multi-dose St. Thomas' Hospital cardioplegic solution number 1 in the ischemic and reperfused neonatal rabbit heart. In addition, the effect of including bicarbonate (a component of St. Thomas' Hospital cardioplegic solution number 2) was also studied. Hearts (n = 8 per group) were excised from rabbits (7-10 days old) and aerobically perfused in the working mode with crystalloid media for 20 min (37 degrees C). After assessing cardiac function, the hearts were arrested by an infusion of cold cardioplegic solution (2 min at 15 degrees C) with or without the addition of bicarbonate (10 mmol). The hearts were then subjected to 6 h of hypothermic ischemia (15 degrees C) and, during this period, some hearts received multiple infusions (2 min/h at 15 degrees C) of cardioplegic solution. All hearts were reperfused for 35 min (15 min Langendorff plus 20 min working), cardiac function was then re-assessed and expressed as a percent of the preischemic value. The coronary effluent, collected during the first 15 min of reperfusion, was assayed for creatine kinase activity. At the end of the reperfusion period, the hearts were freeze clamped and taken for metabolic analysis. With multi-dose cardioplegia (without bicarbonate) the postischemic recovery of cardiac output was 67.0 +/- 6.5% and with single-dose the value was 39.3 +/- 10.0% (NS). The same pattern of postischemic recovery (that varied between 30% and 60%) for aortic flow, stroke volume and stroke work was observed with both multi-dose and single-dose infusion.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Comparison of single- and multi-dose crystalloid cardioplegia to protect the immature myocardium. 769 29


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