[Prevention of brain damage during heart surgery].
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Biomedical subjects
Publications and source records attributed to M Kaste.
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Increasing evidence suggests that snoring and sleep apnea are associated with cerebrovascular diseases. Several other factors may be involved in this association because many established or potential risk factors for stroke are related to snoring and sleep apnea. These include arterial hypertension, coronary heart disease, age, obesity, smoking, and alcohol consumption. Recent epidemiologic and clinical studies indicate, however, that snoring can increase the risk of stroke independently of these confounding factors. Accumulating epidemiologic evidence of long-term harmful effects of the obstructive sleep apnea syndrome appears to be related to increasing vascular morbidity and mortality. Potential mediators among snoring, obstructive sleep apneas, and stroke include cardiac arrhythmias and other hemodynamic disturbances, increased levels of catecholamines, and disturbances in cerebral blood flow caused by sleep apneas, as well as hypoxemic periods that may potentiate atherosclerosis.
We studied 30 patients 24 hours after out-of-hospital cardiac arrest and 13 age-matched normal controls with the use of technetium Tc 99m-hexamethylpropyleneamine oxime single photon emission computed tomography. All patients were followed up for 12 months or until death. Frontal hypoperfusion (anteroposterior perfusion ratio, less than 0.90) was observed in 23 patients (77%). In eight patients who remained comatose and died, the total size of perfusion defects was larger (38% +/- 20%) than in the 21 patients who recovered consciousness (24% +/- 14%), but the anteroposterior ratio was similar in both of these patient groups (0.83 +/- 0.09) and significantly lower than in the controls (0.96 +/- 0.03). During follow-up, both the anteroposterior perfusion ratio and the relative defect size improved, but frontal hypoperfusion was still observed in seven of 13 patients. After cardiac arrest, regional cerebral blood flow is characterized by frontal hypoperfusion that tends to improve over time but that persists in most patients.
We studied the effects of repeated bicycle exercises and ethanol ingestion (1.5 g/kg) on platelet aggregation and thromboxane (TxB2) release in 10 healthy male volunteers. After a bicycle exercise performed in the morning, the adenosine diphosphate (ADP)-induced platelet aggregation and the aggregation-associated thromboxane release were found to be decreased in fasting men. In contrast, after ingestion of fruit juice and a second exercise at noon, platelet aggregation and thromboxane release were increased. These latter changes were negligible when ethanol was ingested together with fruit juice. A third exercise, performed in the evening, again caused a decrease in the aggregation and associated thromboxane release during the control session, but provoked an increase during the ethanol session. Exercise increased the urinary excretion of 2,3-dinor-6-keto-PGF1 alpha. Changes in the plasma arachidonic acid (AA) concentration probably influenced the platelet thromboxane release. The results suggest that both physical exercise and ingestion of ethanol in fruit juice influence the ADP-stimulated platelet thromboxane release.
We studied adenosine diphosphate-induced platelet aggregation and the associated release of thromboxane B2 in 49 patients with subarachnoid hemorrhage in relation to angiographic vasospasm. Postoperative cerebral angiography was performed less than or equal to 3 (median 1) days after surgery for an aneurysm 5-14 days after subarachnoid hemorrhage. Correspondingly, one sample from each patient was taken within 24 hours either before or after angiography. The occurrence of severe as well as diffuse, moderate, or severe angiographic vasospasm was associated with the presence of delayed cerebral ischemia (p less than 0.05). Patients with diffuse angiographic vasospasm had significantly higher (p less than 0.05) values for thromboxane B2 release than the others, even after adjustment by the clinical grades on admission and before surgery, the timing of surgery, the time from subarachnoid hemorrhage to angiography and blood sampling, and nimodipine therapy. Severe and diffuse angiographic vasospasm were also associated with poor outcome at 1 year (p less than 0.05). Our results suggest that augmented release of platelet thromboxane may be involved in the pathogenesis of vasospasm in large cerebral arteries.
Serial blood samples were obtained from 80 patients with subarachnoid hemorrhage (SAH) to study adenosine diphosphate-induced platelet aggregation and associated thromboxane B2 release. The goal of the investigation was to detect whether reduced platelet function is involved in rebleeds. Seventeen patients (21%) suffered a rebleed, six of those experiencing their first rebleed within 24 hours after SAH. Therefore, most platelet function studies were performed after rebleeds. Thromboxane release was lower in patients with rebleeds than in the others, both before and after rebleeding, although statistical significance was reached only in samples collected after rebleeds. Patients rebleeding within 24 hours after SAH had lower platelet aggregability (p = 0.037) than patients without a rebleed in the samples taken within 3 days after SAH. The results suggest that reduced platelet aggregability and thromboxane release are involved in rebleeds following primary SAH.
Adenosine diphosphate-induced platelet aggregation and associated thromboxane B2 release were studied in 52 patients with subarachnoid hemorrhage (SAH) in order to detect a possible association between altered platelet function and development of cerebral ischemic complications after SAH. Compared to the values on admission, the patients showed significantly increased platelet aggregability (p less than 0.05) and thromboxane release (p less than 0.001) 1 to 2 weeks after SAH. The highest values of thromboxane release were seen in patients who deteriorated due to delayed cerebral ischemia with a permanent neurological deficit. Thromboxane release was significantly higher (p less than 0.05) before the onset of severe delayed ischemia in six patients with preoperative ischemia compared to the patients without delayed ischemia. In five others, both ischemic deterioration and elevated thromboxane release occurred after operation. These patients had preoperative values similar to the values in those without ischemic symptoms. The observations suggest that increased platelet aggregability and thromboxane release are associated with delayed cerebral ischemia both before and after surgery.
One hundred fifty-five consecutive patients resuscitated after out-of-hospital ventricular fibrillation by a physician-manned advanced life support unit were randomly assigned to receive nimodipine or placebo at a dosage of 10 micrograms/kg as an intravenous injection immediately after restoration of spontaneous circulation, followed by an infusion of 0.5 micrograms/kg per minute for 24 hours. No significant difference was found in the 1-year survival rate of nimodipine-treated (30 [40%] of 75 patients) and placebo-treated patients (29 [36%] of 80 patients). Recurrent ventricular fibrillation during the treatment occurred in one patient in the nimodipine group compared with 12 patients in the placebo group. In a post hoc analysis of patients with very long delays in advanced life support (more than 10 minutes), the 1-year survival rate was higher with nimodipine (eight [47%] of 17 patients) than with placebo (two [8%] of 26 patients). Nimodipine may be of benefit in patients with delayed resuscitation.
We studied adenosine diphosphate-induced platelet aggregation and the associated release of thromboxane B2 in platelet-rich plasma from 88 patients with subarachnoid hemorrhage and 26 healthy controls. During the first 3 days after subarachnoid hemorrhage, the patients showed significantly decreased (p less than 0.05) platelet aggregability and thromboxane release relative to the controls, but these effects disappeared in a few days. Platelet count increased for 3 weeks after subarachnoid hemorrhage. Surgery in 67 patients was followed by significant increases in platelet aggregability (p less than 0.05) and thromboxane release (p less than 0.001). Greatest thromboxane release was found in the eight patients showing delayed (postoperative) ischemic deterioration with a permanent neurologic deficit. Although platelet hyperaggregability and increased thromboxane release were particularly prominent in these eight patients, the role of these hematologic parameters in the pathogenesis of delayed ischemic deterioration remains unclear.
We studied platelet function in 41 patients with subarachnoid hemorrhage who were randomized to receive either nimodipine or placebo in a double-blind fashion. Nimodipine was given to 21 patients, intravenously for 7-10 days and then orally until 21 days after the subarachnoid hemorrhage. The other 20 patients received placebo in a similar manner. Nimodipine did not significantly influence platelet aggregability. For the first 1-5 days after the subarachnoid hemorrhage, nimodipine treatment did not have any notable effect on adenosine diphosphate-induced platelet thromboxane B2 release, but a significant (p less than 0.05) inhibitory effect was observed thereafter. During intravenous administration, nimodipine prevented the increase in thromboxane release otherwise observed after subarachnoid hemorrhage. Concomitant with the decrease in thromboxane release, nimodipine increased the platelet count both before and after surgery so that the capacity for thromboxane formation per liter of blood decreased less than expected on the basis of thromboxane release per 10(7) platelets. Our study suggests that nimodipine might diminish the chance of cerebral ischemia by inhibiting platelet thromboxane release.
Recent findings on the relation between alcohol abuse and ischaemic brain infarction are reviewed. Much of the association has hitherto been explained by the effects of confounding factors such as smoking. Alcohol increases blood pressure in both hypertensive and normotensive subjects and alcohol induced hypertension enhances the risk of both hemorrhagic and ischaemic strokes. Analysis of case histories shows that alcohol abuse has precipitated cerebral embolism in conjunction with cardiac diseases including alcoholic cardiomyopathy and paradoxical embolism due to deep vein thrombosis via atrial septal defect. Among young adults, falling when intoxicated with alcohol has caused traumatic dissection of the carotid artery and consequent brain infarction. Alcohol may predispose individuals to cerebral embolism, thrombosis and ischaemia via its effects on the coagulation cascade, platelet count and function and contractility of the cerebral vessels. Further studies are needed to prove that these mechanisms are significant and to identify any other mechanisms which may mediate the risk associated with alcohol abuse. On the basis of current data, alcohol should be considered as an independent risk factor for ischaemic cerebral infarction in young adults.
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The prognostic value of cerebrospinal fluid (CSF) and serum neuron-specific enolase and brain-type creatine kinase isozyme (CK-BB) measurements was studied in 75 consecutive victims of out-of-hospital cardiac arrest. All patients with a CSF neuron-specific enolase level of more than 24 ng/mL 24 hours after cardiac arrest remained unconscious and died. The CSF CK-BB level was as reliable as an index of brain injury. Cerebrospinal fluid neuron-specific enolase, CSF CK-BB and serum neuron-specific enolase levels correlated with the neurological outcome at 3 months. Thus, the analysis of these enzymes in CSF seems to be useful in the early prognostic assessment of cardiac arrest victims.
The association between dental infections and cerebral infarction was investigated in a case-control study involving 40 patients with ischaemic cerebral infarction under the age of 50, and 40 randomly selected community controls matched for sex and age. Poor oral health, as assessed by two indices measuring the severity of infections of teeth and periodontium, or by the presence of subgingival calculus or the presence of suppuration in the gingival pockets, were more common in male patients than in male controls, but no difference was observed in females. If severe dental infections were combined with other probable bacterial infections there were altogether 16 patients (40%) but only two controls (5%) who had suffered from a probable bacterial infection within 1 month or at the time of the stroke or when examined as a control (P less than 0.01). Our results suggest an association between bacterial infection and ischaemic cerebrovascular disease in patients under 50 years of age. Severe chronic dental infection seems to be an important type of infection associated with cerebral infarction in males.
The effects of earlier surgery and shorter bedrest on the outcome in 338 consecutive patients with subarachnoid haemorrhage admitted within five years to a primary emergency hospital were evaluated. Mortality from rebleeds diminished more than surgical mortality increased. Shortened bedrest did not increase the number of rebleeds in patients not operated on. The combined mortality from rebleed and surgery decreased by 32% and the overall mortality by 21%.
We studied 177 consecutive male patients aged 16-60 years with brain infarction verified by neuroradiology and analyzed the time of onset of stroke symptoms related to sleep and the role of possible or known risk factors for brain infarction. Brain infarction occurred relatively more often during the first 30 minutes after awakening than at any other time. In multiple stepwise logistic regression analyses, snoring was the only independent risk factor differentiating stroke occurring during sleep and stroke occurring either during sleep or during the first 30 minutes after awakening from stroke occurring at other times of the day. The risk ratios were 2.65 (95% confidence interval 1.32-5.29, p less than 0.005) and 3.16 (95% confidence interval 1.61-6.22, p less than 0.001), respectively. Other factors tested were age, arterial hypertension, diabetes mellitus, smoking, alcohol consumption, and body mass index. Arterial hypertension seemed to have an additive effect on the independent risk caused by snoring.
In a prospective study, 52 patients with a spontaneous supratentorial intracerebral hematoma (ICH) were randomly assigned to receive emergency surgery or conservative treatment within 48 hours after the bleed. Patients with a decreased level of consciousness and/or a severe neurological deficit were admitted to the study. The overall mortality rate at 6 months was 42%: 10 (38%) of the 26 patients in the conservative group and 12 (46%) of the 26 in the surgical group. Six (20%) of the 30 survivors at 6 months were able to conduct their activities of daily living independently: five (31%) of the 16 patients in the conservative group and one (7%) of the 14 in the operative group. These differences are not statistically significant. The mortality rate of semicomatose or stuporous patients (Glasgow Coma Scale score 7 to 10) was statistically significantly lower in the surgical group (none of the four patients) than in the conservative group (four of five patients) (p less than 0.05); however, all surviving patients in this subgroup were severely disabled. The study suggests that surgical treatment of this category of patients with ICH does not offer any definite advantage over conservative treatment. In semicomatose or stuporous patients, surgery may improve the length of survival, but the quality of life remains poor.