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Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Toxic injury is one of the many ways by which the functional integrity of the heart may become compromised. Any of the subcellular elements may be the target of toxic injury, including all of the various membranes and organelles. Understanding the mechanisms underlying cardiotoxicity may lead to treatment of the toxicity or to its prevention. Doxorubicin and its analogs are very important cancer chemotherapeutic agents that can cause cardiotoxicity. Other agents which are cardiotoxic and which have profound public health implications include the alkaloid emetine in ipecac syrup, cocaine, and ethyl alcohol. The most important cardiotoxic mechanisms proposed for doxorubicin include oxidative stress with its resultant damage to myocardial elements, changes in calcium homeostasis, decreased ability to produce ATP, and systemic release of cardiotoxic humoral mediators from tissue mast cells. Each of the first 3 mechanisms can lead to each of the other 2, and the causal relationships between all of these mechanisms are not clear. New evidence suggests that doxorubicinol, one of the metabolites of doxorubicin may be the moiety responsible for cardiotoxicity. Several other potential mechanisms also have been proposed for doxorubicin. Emetine in ipecac syrup is the first aid treatment of choice for many acute toxic oral ingestions and the alkaloid, itself, is used to treat amebiasis. Cardiotoxicity occurs following chronic exposure, such as occurs therapeutically in amebiasis and with ipecac abuse by bulemics. A number of mechanisms are proposed for emetine cardiotoxicity, but the current mechanistic literature is quite scarce. Cocaine abuse recently has caught the public interest, in particular because of the drug-related sudden deaths of certain athletes. Cocaine can cause hypertension, arrhythmias, and reduced coronary blood flow, each of which can contribute to its lethality. However, it may be possible that cocaine sudden death episodes are more related to hyperthermia and convulsive seizures, rather than to cardiovascular toxicity. Chronic alcohol use leads to dilated cardiomyopathy and failure as part of the general physical degeneration that occurs with alcoholism. Several mechanisms are proposed for the cardiomyopathy, but only 2 things seem clear. The cardiotoxicity is due to an intrinsic effect of alcohol, rather than to malnutrition or co-toxicity, and abstinence is the only effective treatment for the cardiomyopathy. Recent articles indicate that very moderate use of alcohol may be beneficial and protect against cardiovascular-related morbidity. One explanation for these findings seems to be that the non-drinking groups, against whom the moderate drinking comparisons were made, were enriched in former drinkers with significant alcohol-related cardiovascular pathology.
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PMID:Toxic mechanisms of the heart: a review. 209 Dec 37

To better understand and treat painful conditions, one needs to identify the cause, discover the source, and develop knowledge of peripheral and central pain transmission; headaches are no exception. The development of appropriate animal models is important. Accordingly, we have reviewed the anatomy, neurochemistry, electrophysiology, and pharmacology of the trigeminovascular system in experimental animals and emphasized whenever possible the relevance of this final common pathway to migraine, cluster, and other headache syndromes in humans. For example, based on recent anatomic dissections, the pericarotid cavernous sinus plexus was suggested as an important focus to investigate cluster headache pathophysiology. This plexus is an anatomic point of convergence for the nerves giving rise to the signs of sympathetic and parasympathetic activity and sensory symptoms that develop in cluster patients. As in other nociceptive systems, trigeminovascular axons assume at least two important roles. One concerns the transmission of nociceptive information. Electrophysiologic evidence supports the trigeminal nucleus caudalis as an important site for the convergence of visceral (vessel) and somatic (forehead) inputs to mediate the referral of vascular pain to superficial tissues. A second important role concerns the initiation of local increases in blood flow and enhanced protein permeability (sterile inflammation) via the axonal release of vasoactive neuropeptides. Plasma extravasation develops within the dura mater following trigeminal stimulation. Extravasation can be blocked by the administration of ergot alkaloids or sumatriptan, a new serotonin-like agonist, and a prejunctional (neuronal) mechanism of action for these drugs (such as blockade of release) was suggested based on experimental evidence. Whether vasoconstriction also relates to the therapeutic efficacy remains to be determined. As in other organ systems, real or threatened tissue injury provides an important stimulus for depolarizing sensory fibers. The stimulus may come from external conditions such as reduced blood flow or hypoglycemia. The brain may also possess intrinsic neuronal mechanisms by which nociceptors may be synthesized (e.g., glutamate-induced neurotoxicity, seizures). Molecules of relevance include bradykinin, prostaglandins, leukotrienes, and potassium. Experimental evidence was presented demonstrating that the trigeminal nerve mediates hyperemia within cortical gray matter by axon-reflex like mechanisms. An important role for this nerve was established during the hyperemic period of recirculation after ischemia or during severe hypertension above the limits of autoregulation.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Basic mechanisms in vascular headache. 217 82

Violent shaking causes severe injury in infants, but the diagnosis of shaken baby syndrome is often difficult to make because of the lack of obvious external signs. Consultations by other specialists may not be helpful, since the findings of most organ systems, taken in isolation, are usually nonspecific. Shaken baby syndrome should be considered in infants presenting with seizures, failure to thrive, vomiting associated with lethargy or drowsiness, hypothermia, bradycardia, hypertension or hypotension, respiratory irregularities, coma or death. Shaken babies are usually less than one year old, and most are under six months of age. Head injury (notably subdural hemorrhage) and retinal hemorrhages are the hallmarks of the syndrome.
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PMID:Shaken baby syndrome. 218 31

Only 6 patients with intracranial hypertension associated with unruptured cerebral arteriovenous malformations have been reported. We report 6 additional patients seen at the Cleveland Clinic during the past 10 years. The average age was 28 years (range, 19-44 years); 4 were women. Symptoms and signs included papilledema (6 patients), headache (6), transient nonepileptic focal symptoms (4), visual obscurations (3), ipsilateral carotid or ocular bruits (3), abnormal visual fields (3), focal seizures (2), and progressive visual loss (1). Enhanced computed tomography (CT) or magnetic resonance imaging (MRI) demonstrated the malformations in all 6 patients. The malformations were large, supplied by the branches of the middle and anterior cerebral arteries, with the posterior cerebral artery contributing in 3 patients, and all drained into the superior sagittal sinus. Associated venous obstruction was seen in 2 patients. Four patients underwent excision of the arteriovenous malformation, with resolution of papilledema in all 4. Measurements of cortical arterial and venous pressures during surgery in 3 patients showed decreased feeding artery pressures and elevated draining vein pressures, which normalized after removal of the malformation. Treatment in the 2 remaining patients consisted of medical therapy (acetazolamide, furosemide, steroids) alone in 1 patient, and in conjunction with proton beam radiation in the other. Papilledema resolved in the former patient, but the patient receiving proton beam radiation still had papilledema 2 years later. Intracranial hypertension associated with unruptured cerebral arteriovenous malformations occurs in young patients with high flow malformations that drain into the superior sagittal sinus, and is likely the result of increased cortical venous and superior sagittal sinus pressure. Excision of the malformation effectively reduces the intracranial pressure.
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PMID:Intracranial hypertension associated with unruptured cerebral arteriovenous malformations. 219 10

The data were reviewed of 76 patients with supratentorial intracerebral hemorrhage, including 38 lobar (LH) and 38 basal ganglion (BGH) hemorrhages. Our aim was to define the clinical and tomodensitometric profiles of the two lesions. Men seem to be at higher risk of BGH and women more frequently of LH. Among the risk factors and causes, only chronic hypertension proved to be clearly associated with BGH. Wide variability of clinical course was observed. However, LH was associated more frequently with headache, initial seizure and show installation over more than 12 hours. CT sections revealed association of intraventricular hemorrhage with BGH. No difference in short term prognosis was found between LH and BGH.
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PMID:[Supratentorial intracerebral hemorrhage]. 219 19

Phenylpropanolamine (PPA) is contained in about 106 products, over half of which are available over-the-counter (OTC). Most are cough/cold remedies; nine are OTC diet aids. More than nine million Americans were using OTC diet aids in 1981, making PPA the fifth most used drug in the United States, responsible for over $200 million in revenues. The safety of PPA remains controversial. Although most controlled studies indicate minimal pressor effects with recommended doses, adverse drug reactions (ADRs) continue to be documented. Since 1965, 142 ADRs have been reported in 85 studies, 69% of these in North America. Many such cases may go unrecognized. About two thirds of all ADRs occurred in females and in patients under 30. Of ADRs attributed to legitimately sold PPA products, 85% occurred after consumption of OTC products versus only 15% after prescription drugs. The PPA product often contained combination ingredients, or PPA was consumed along with additional drugs. An overdose of PPA was taken in about a third of the cases. After ingestion of non-overdose amounts, 82% of the ADRs were severe. The most frequent side effects involved symptoms compatible with acute hypertension, with severe headache the most common complaint. Twenty-four intracranial hemorrhages, eight seizures, and eight deaths (most due to stroke) were associated with PPA ingestion. We have summarized these data in an effort to alert clinicians to the prevalence of usage of PPA products and the potential for adverse effects. In patients who present with elevated blood pressure or signs of acute hypertension, especially hypertensive encephalopathy of undetermined origin, we recommend inquiry about recent ingestion of PPA-containing diet aids and cough/cold products and suggest having such patients remain upright rather than supine.
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PMID:Adverse drug effects attributed to phenylpropanolamine: a review of 142 case reports. 220 Feb 64

Between 1984 and 1989, orthotopic cardiac transplantations were done in 90 patients from 10 to 65 years of age for end-stage, refractory congestive cardiomyopathy. Two patients had had ischemic strokes 5 months and 18 years, respectively, before transplantation. Six patients (7%) suffered acute neurologic events perioperatively. Three patients suffered cerebral infarctions. In 1 case this occurred 10 days before transplantation--probably as a result of systemic hypoperfusion--with the placement of ventricular assist devices. Two others suffered infarctions 5 and 21 days, respectively, after transplantation, each of probable embolic origin. Two patients had an acute intracerebral hemorrhage 21 and 36 days, respectively, after transplantation; both were located within the basal ganglia and subcortical regions. Both patients had moderate to severe hypertension, and in 1, renal failure and a coagulopathy developed before hemorrhage. Tremor, seizures, and an altered level of consciousness developed in 1 patient as an apparent toxic reaction to cyclosporine treatment. Only 1 patient died as a result of the neurologic complication--of an acute intracerebral hemorrhage. Three patients recovered fully, 2 partially. Only the case of drug toxicity could be directly attributed to the transplantation procedure itself. We conclude that the risk of an acute neurologic insult with orthotopic cardiac transplantation is low but may result from drug toxicity, cerebral ischemia, or hemorrhagic mechanisms.
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PMID:Neurologic complications of cardiac transplantation. 221 70

A prospective, consecutive series of 307 patients with aneurysmal subarachnoid hemorrhage ranging from Grades 1 to V according to the classification of Hunt and Hess on admission were evaluated to determine the incidence of epilepsy 1 to 3 years (mean, 1.4 years) after aneurysmal subarachnoid hemorrhage (SAH) and surgery. Sixty-three patients had died and one patient was lost to follow-up. Twenty-nine patients developed epileptic seizures after the SAH and surgery. The mean time from the SAH to epileptic seizure varied from 0 days (day of the SAH) to 2 years (mean, 6.7 months). The seizures were classified as focal in 9 patients (31%) and as generalized in 20 patients (69%). All patients received anticonvulsant medication after more than one seizure. The risk factors for development of posthemorrhagic/postoperative epilepsy were, in order of importance: a history of hypertension; an infarct on late computed tomographic scan; and the duration of coma after the ictus. Of the 85 patients with histories of hypertension, 17 (20.0%) developed epilepsy. Only 12 (5.4%) of the 222 nonhypertensive patients developed epileptic seizures. The difference between the groups was significant (P = 0.0001). Computed tomographic scans were undertaken in 237 patients 1 to 3 years (mean, 1.4 years) after the SAH and surgery. Postoperative epilepsy was significantly associated with infarcts visualized on computed tomographic scan (P = 0.0005).
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PMID:Hypertension as a risk factor for epilepsy after aneurysmal subarachnoid hemorrhage and surgery. 223 61

To investigate the possible etiologic factors of late onset seizures of unknown origin, 50 consecutive patients whose seizures started after age 50 and who had a normal CT, were screened. The seizures in this group were generalized in 70% and infrequent. The hypothesis that late-onset seizures of unknown origin were frequently due to microinfarcts, was evaluated by comparing the frequency of arterial hypertension, coronary heart disease, peripheral vascular disease, carotid bruits, diabetes mellitus and smoking in these patients with appropriate control groups. The results showed that the frequencies of these cardiovascular risk factors were similar to those of sex and age-matched controls and much lower than in a comparable series of patients whose seizures followed a stroke, or patients with stroke but not seizures. These data suggest that subclinical cerebrovascular disease is probably not a frequent etiology of late-onset epilepsy of unknown origin. The cause of these seizures remains to be elucidated.
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PMID:Seizures of unknown origin after the age of 50: vascular risk factors. 223 42

Clinical reports have suggested that therapy with fresh frozen plasma is a useful adjunct in the management of the hemolytic-uremic syndrome (HUS). We reviewed the charts of 36 children with severe HUS who were treated at the Izaac Walton Killam Hospital for Children, Halifax, over 10 years to assess the effectiveness of plasma therapy. All children who required specific supportive therapy for renal dysfunction, hemolysis or serious extrarenal complications were included. We compared the outcome of 18 children who received plasma therapy from 1982 to 1987 with that of 18 children who did not. The two groups were similar with regard to the severity of HUS, the length of hospital stay, the duration of renal dysfunction and the incidence of disease-related complications, such as seizures, enterocolitis and cardiomyopathy. At discharge the prevalence of hypertension was higher in the plasma therapy group than in the control group. Plasma therapy did not demonstrate any benefit that would outweigh the risk of fluid overload, hyperproteinemia and transmission of viral infection.
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PMID:Plasma therapy for severe hemolytic-uremic syndrome in children in Atlantic Canada. 225 39


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