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

The low mortality and perioperative infarction rates for aortocoronary bypass (ACB) make them unsuitable for evaluating the adequacy of myocardial protection. Enzymatic and functional measurements were found to be sensitive and specific indicators of myocardial injury. A prospective concurrent study of 78 patients undergoing triple ACB was conducted to evaluate the effectiveness of three popular methods of myocardial protection. Group I (32 patients) had a single dose of cold (4 degrees C) potassium cardioplegic (CPC) solution infused inducing a mean myocardial temperature (MMT) of 31 +/- 4 degrees C/min. Group II (23 patients) had multiple doses of CPC solution 8nducing a MMT of 22 +/- 2 degrees C/min. Group III (23 patients) had intermittent anoxic arrest at a MMT of 28 +/- 1 degrees C. The groups were not randomized but had comparable clinical symptoms and catheterization findings. Serial measurements of cardiac specific creatine kinase (CK-MB) revealed a peak in enzymatic activity occurring 60 minutes following ACB. The highest CK-MB was significantly (P less than 0.01) lower in group II (25 +/- 8 IU/liter) than group I (50 +/- 8 IU/liter), or group III (68 +/- 14 IU/liter). Myocardial performance was evaluated after ACB by serially measuring left ventricular stroke work index (SW) and left atrial pressure (LAP) in response to volume loading. The rise in SW was significantly (P less than 0.01) greater in group II (3.0 +/- 0.7 gm.m/sq m/mm Hg) than in group I (1.4 +/- 0.7) or group III (1.8 +/- 0.9). The highest SW attained was higher (P less than .01) in group II (43 +/- 7 gm.m/sq m) than group I (19 +/- 6) or group III (34 +/- 8) at comparable LAP values (group I: 20 +/- 5 mm Hg; group II: 18 +/- 3; group III: 18 +/- 4). Post-operative clinical evaluation failed to differentiate among the three groups. The more sensitive indices, however, demonstrated the superiority of cold, multidose cardioplegia in providing optimal myocardial protection.
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PMID:Optimal myocardial protection. 30 65

Twenty-four pigs were studied to assess the effect of potassium in a cardioplegic solution on the ability of the swine myocardium to maintain functional and metabolic integrity following induced ischemia. The pigs were evaluated on total and right heart bypass with measurement at normothermia and after a one-hour intervention of stroke volume (SV), coronary blood flow (CBF), myocardial oxygen consumption (MVO2), and lactate extraction. Myocardial tissue gases (PmO2 and PmCO2) were continuously monitored and, at the conclusion of the procedure tissues were analyzed for adenosine triphosphate (ATP). There were five interventions: (1) hypothermic perfusion (28 degrees C) (Group 1); (2) hypothermic ischemia (28 degrees C) (Group 2); and hypothermic ischemia with a cardioplegic solution (nonlactated Ringer's solution, pH 7.4, 4 degrees C) using (3) normokalemia (4 mEq of potassium chloride/L, 300 mOsm/L (Group 3), (4) hyperkalemia (43 mEq of KCl/L, 390 mOsm/L) (Group 4), and (5) normokalemia with increased osmolarity (3.6 mEq of KCl/L, 400 mOsm/L) (Groups 5). A significant decrease in SV and elevation in peak PmCO2 were seen in all groups subjected to ischemia except those protected with hyperkalemic solution. We conclude that the presence of hyperkalemia in a cold root perfusion solution provides better myocardial protection than cold root perfusion alone. Furthermore, potassium arrest appears to be more protective than coronary perfusion at 28 degrees C.
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PMID:The importance of hyperkalemia in a cold perfusion solution: a correlative study examining myocardial function, metabolism, tissue gases, and substrates. 48 29

Cardiorespiratory, thermal, and renal responses to a 30-min head-out immersion in 15 degree C water were studied at 1-ATA air and 11-ATA helium-oxygne environments in four male subjects wearing dry suits. Cardiorespiratory responses to immersion (reductions in heart rate, expiratory reserve volume, vital capacity, and thoracic impedance; and increases in stroke volume, cardiac output, and inspiratory capacity) were comparable at both pressures. However, thermal responses to immersion (a reduction in mean skin temperature and increases in skin heat flux and suit conductance) were significantly greater at 11 ATA compared to those at 1 ATA. The rate of urinary excretion of norepinephrine increased significantly during and after immersion at 11 ATA but not at 1 ATA. In contrast, the urinary excretion of epinephrine was not altered by pressure or immersion. The immersion diuresis was greater and lasted longer at 11 ATA than at 1 ATA although there was no difference in the endogenous creatinine excretion . This diuresis was accompanied by a significant natriuresis which was more marked at 1 ATA than at 11 ATA. At 1 ATA, the urinary excretion of both aldosterone and antidiuretic hormone (ADH) decreased during immersion. At 11 ATA, the rate of excretion of these hormones before immersion was lower compared to that at 1 ATA and did not change significantly during immersion. These results indicate that immersion in a hyperbaric helium-oxygen environment presents a greater cold stress than at 1-ATA air, and also that immersion diuresis and natriuresis at high pressure may be induced by a factor other than inhibition of aldosterone and ADH.
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PMID:Physiological responses to head-out immersion in water at 11 ATA. 63 73

Diphenyl-para-phenylenediamine (DPPD) is an antioxidant that has been shown to decrease liver damage due to the peroxidative process of carbon tetrachloride in rats and to ameliorate cold-induced cerebral edema in cats. Because lipid peroxidation disrupts the integrity of the plasma membrane, a process believed to occur in cerebral infraction, which is a major cause of cerebral edema. DPPD was tested for its protective effect against cerebral infarction. When given intraperitoneally in gerbils with unilateral ligation of the common carotid artery, DPPD had no effect on resultant incidence, morbidity, or mortality of cerebral infarction. Despite these findings, the authors believe, on the basis of what is known about free radical pathology, that DPPD and other antioxidants deserve further laboratory trials as possible drugs in the treatment of brain trauma and cerebral edema.
Stroke
PMID:Effect of DPPD (diphenyl-para-phenylenediamine) on stroke and cerebral edema in gerbils. 70 30

1) It is generally accepted that the adequate environmental temperature to rear rats is about 23 degrees C, but the adequate temperature that directly contacts to the animal's skin seems to be about 30 degrees C. 2) The blood pressure increased on cold exposure or stimulation. There was a case that the blood pressure increased slightly on hot exposure. This suggests that it is necessary to pay close attention to the condition of warming-up at the indirect measurement of blood pressure. 3) Apoplexy seemed to occur earlier at the low environmental temperature, and the blood pressure seemed to increase also at the high temperature. However, these temperature effects on blood pressure and the incidence of stroke were not so obvious as observed in rearing SP with 0.9% salt solution for drinking.
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PMID:Blood pressure in stroke-prone SHR (SHRSP) exposed to unusual environmental temperature. 73 3

Alpha methyl tryosine (AMT), and inhibitor of norepinephrine (NOR) synthesis, was injected intraperitoneally (200 mg/kg) in Sprague Dawley rats, kept in a cold room, or at room temperature for 16 hours. Using formaldehyde induced NOR fluorescence, nerve counts were made on whole mounts of cerebral and femoral arterioles 14-300 micronm in diameter, utilizing a grid superimposed on the vessels. Cold had no effect on the number of visible (i.e. fluorescing) nerves. AMT had an appreciable effect but only on nerves to femoral arterioles, where a significant reduction in nerve count was observed in both cold stressed and non stressed rates, when compared with animals not given AMT. Since the counting technique is sensitive only to large depletions of NOR, we cannot conclude that AMT failed to affect NOR content in cerebrovascular nerves. However, if such an effect was present, it was much less than the effect of AMT on nerves to femoral vessels. We suggest that the differential effect of AMT on these 2 vascular beds may indicate a lower basal level of NOR release from cerebrovascular nerves, which would correlate with the difficulty of demonstrating basal sympathetic tone in this vascular bed.
Stroke
PMID:Comparison of nerves to cerebral and extracerebral blood vessels: a differential effect of alpha methyl tyrosine on norepinephrine content. 87 Oct 27

Impedance plethysmography was used to measure resting cardiac stroke volume (SV) and thoracic conductive volume (TCV) in four divers at intervals during a prolonged dry saturation dive (17 days at 18.6 ATA and 7 days' decompression). Resting heart rate (HR), blood pressure (BP), and pulmonary minute ventilation (VE) were measured 4 times per day for the duration of the 30-day experiment. The vital capacity (VC) and its subdivisions IC and ERV were measured by spirometry every 3 days. In nonsmokers, VC fell significantly with time (r = 0.64), while VC in smokers increased nearly 400 ml during the first week at pressure before tending to fall with time. Compared to predive, the mean ERV was increased 629 ml at pressure, while VE and respiratory rate were not changed. The increased ERV did not persist postdive and was probably the result of the increased work of breathing a dense gas (4.1 g/liters). Residual volume (RV) measured by nitrogen dilution before and after the dive increased 38% and remained significantly increased (22%) even after one year in 4 divers. It is suggested that hyperoxia (0.3 ATA PO2) combined with increased gas flow resistance caused the VC to fall and RV to increase. The major cardiovascular findings were a transient bradycardia associated with increased stroke volume leading to a significant increase in resting cardiac output associated with an increased rate of rapid ventricular filling, TCV, and BP at depth. Lowering the ambient temperature for 3 days did not re-establish the bradycardia, suggesting that hyperbaric bradycardia is not due to a subtle cold stress.
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PMID:Hana Kai II: a 17-day dry saturation dive at 18.6 ATA. IV. Cardiopulmonary functions. 91 Mar 17

1. The cardiovascular changes of conscious cold-acclimated (CA) and warm-acclimated (WA) rats during exposure to 5 degrees C or 28 degrees C were studied. 2. The cardiac output, heart rate and stroke volume of Ca rats exposed to 5 degrees C and of WA rats during cold stress were significantly greater, and their calculated total peripheral resistance significantly less than those of WA rats ats exposed to 28 degrees C. These results show that circulatory changes participate in cold acclimation and cold stress. The circulatory changes in the two conditions were compared and the mechanism of the observed differences were discussed. 3. CA rats exposed to 28 degrees C showed a striking decrease of oxygen consumption and arterio-venous O2 difference, but significant circulatory changes were decreased heart rate and cardiac index only, indicating that the response was mainly metabolic.
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PMID:Circulatory changes in cold-acclimation and cold stress. 97 31

Forty-one patients undergoing aortocoronary bypass surgery were divided into two groups: an "unclamped" group (17 patients) in whom the aorta was not cross-clamped during operation and a "clamped" group (24 patients) in whom the ascending aorta was cross-clamped during performance of distal anastomoses. Myocardial protection was provided during aortic clamping by cooling the anoxic heart with cold saline immersion. Immediate postoperative hemodynamic function was assayed in both groups, as was cardiopulmonary bypass time and cardiopulmonary bypass time/graft. Cardiopulmonary bypass time was 107 minutes in the unclamped group and 87 minutes in the clamped group (P less than 0.05). Cardiopulmonary bypass time/graft was 48 minutes in the unclamped group and 40 minutes in the clamped group (P less than 0.01). Results of hemodynamic studies with values for the unclamped group listed first were as follows: cardiac index (L/min/m2) 2.3 and 2.5 (NS), stroke index (ml/beat/m2) 23 and 25 (NS), left ventricular minute work index (kg-m/min/m2) 3.03 and 2.81 (NS), and stroke work index (g-m/min/m2) 31 and 30 (NS). These data indicate that aortic cross-clamping during performance of distal anastomoses expedites the performance of aortocoronary bypass surgery and does not adversely affect postoperative hemodynamics.
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PMID:Postoperative hemodynamics following aortic cross-clamping during aortocoronary bypass surgery. 109 7

In summary, a prognostic and therapeutic evaluation of 227 patients first seen from 1967 to the end of 1969 with a follow-up of 4-7 years was made. The results are indeed depressing. In spite of close follow-up and systematic treatment with modern antihypertensive agents, the mortality of patients having hypertension with superimposed arteriosclerosis was 27% (15 to 56) for males as contrasted to 3% (2 of 75) for females. Since the last casual blood pressure in both living and deceased patients of the mixed group were similar, the level of blood pressure following treatment could not be incriminated for the deceased patients. An exaggerated systolic and pulse pressure cold pressor response emerged as an important indicator of presence of arteriosclerosis alone. When hypertension and arteriosclerosis coexisted there was also exaggeration in diastolic cold pressor response. A further exaggeration in systolic and diastolic cold pressor response was seen in the decreased as compared to living male patients, a finding which appears to have grave prognostic significance for coronary heart disease and stroke. Thus a marked exaggeration in both systolic and diastolic cold pressor response in males might prove to be the single most important predictor of premature death from atherosclerotic vascular disease. A further analysis of the deceased male patients having hypertension and superimposed arteriosclerosis, indicates that treatment of hypertension may prevent oeath from stroke but not form coronary heart disease. Two-thirds of the deaths occur suddenly and only one-third of the deceased patients reached the hospital befor dying. In view of these distressing findings a plea for early detection and treatment of hypertension, prior to the development of superimposed arteriosclerotic changes, particularly in males, is made.
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PMID:Prognostic and therapeutic considerations in pure hypertension vs hypertension and superimposed arteriosclerosis. 112 46


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