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

Black widow spiders (Latrodectus species) are found worldwide. Envenomation of humans usually occurs as the result of chance intrusion into the spider's domain by the human. The venom is regarded as one of the most potent biologic toxins. The venom acts by destabilization of cell membranes and degranulation of nerve terminals resulting in the release of neurotransmitters. The clinical picture is characterized by painful muscle spasm and hypertension. The very young, the elderly or enfeebled, and those with cardiovascular disease are at greatest risk. While not always necessary, the most effective treatment is specific antiserum. Muscle relaxants, analgesics and intravenous calcium are useful adjuvant treatment.
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PMID:Black widow spider bites. 638 53

Although barbiturates are often effective as therapeutic agents in several types of brain ischemia, there is no consensus as to their mechanisms of action. Exactly why other intravenous anesthetics such as ketamine are not effective therapies in brain ischemia is not known. Structural analogs of ketamine such as phencyclidine (PCP) not only exert potent hallucinogenic properties and are widely abused drugs, but often result in hypertensive encephalopathies and death. In view of the paucity of information on the cerebral circulatory actions of barbiturates, ketamine and PCP (and analogs), in-vivo (microcirculatory) and in-vitro studies were undertaken. Barbiturates, in anesthetic concentrations (e.g., 10(-5) to 10(-4) M), were found to exert direct vasodilator actions on cerebral arterial smooth muscle; these relaxant actions appear to be related to inhibition of calcium ion (Ca2+) influx in cerebral vessels. The latter may be important in the salutory actions of barbiturates in brain ischemia, head trauma and cerebrovasospasm. Unlike barbiturates, ketamine was found to exert spasmogenic actions on cerebral arteries, which may aid in explaining the inability of this anesthetic to be of therapeutic value in brain ischemia. PCP and its analogs, as well as other hallucinogenic molecules (e.g., LSD, mescaline) produced spasms in cerebral arterioles, venules and arteries in concentrations which mimic their hallucinogenic potencies. Distinct PCP-like receptors which subserve contraction appear to exist on large as well as microscopic cerebral blood vessels. Spasms induced by PCP, its analogs and ketamine can be readily reversed or prevented completely by calcium channel blockers. The latter agents could be quite useful, clinically, in prevention of cerebral infarction, hypertension and fatality associated with PCP (and analogs) intoxication.
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PMID:Effects of barbiturates, phencyclidine, ketamine and analogs on cerebral circulation and cerebrovascular muscle. 640 Apr 29

Trauma due to motor vehicles accident and urban violence have made distal arterial reconstruction an increasingly important part of the surgeon's work. During the 20 month period from October 1980 to May 1982, 13 patients with below the knee and 2 patients with forearm trauma had nonviable extremities despite fastidious vascular and orthopedic reconstruction. A continuous intraarterial infusion of tolazoline into the femoral or brachial arteries restored vascular perfusion and viability in 13 of 15 patients (87 percent), with eventual limb salvage in 67 percent. Seven of 15 patients (47 percent) had transient systemic hypertension. There was no mortality. There exists in patients with these catastrophic injuries a local low-flow state due to a combination of distal arterial spasm and venous outflow obstruction. Tolazoline, a peripheral alpha-adrenergic blocking agent, increases blood flow, albeit nonnutritionally, and thus theoretically prevents thrombosis due to stasis in the repaired distal vessel. When limb loss seems inevitable, a trial of intraarterial tolazoline is justified.
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PMID:Devastating distal arterial trauma and continuous intraarterial infusion of tolazoline. 640 43

The plasma catecholamine concentrations have generally been accepted as an index of sympathetic nervous activity in cardiovascular and neurologic disorders. Intracranial vessels are innervated by sympathetic nerve fibers. It is known that the plasma norepinephrine (NE) level is related to the sympathetic activity. Consequently, it is expected that the changes in sympathetic nervous function are accompanied by the release of NE at the sympathetic nerve terminals. There are many reports on the correlation between autonomic nervous system dysfunction and the presence of cerebral arterial spasm, systemic hypertension, ECG evidence of myocardial necrosis after subarachnoid hemorrhage. The present study was undertaken to know whether the measurement of plasma catecholamine concentrations could assess clinical status and have a prognostic value. We examined the plasma NE, epinephrine (E) and dopamine (DA) concentrations in thirty patients with ruptured intracranial aneurysms. Within 48 hours of admission, all patients were evaluated by Hunt & Hess grade depending on the clinical findings. Blood pressure estimations, ECG tracing and a blood sample were obtained. The clinical outcome of the patients was assessed on discharge. The "good" group consisted of patients who recovered completely or with minimal disabilities, and could lead independent lives. The blood samples were assayed by the high performance liquid chromatography. Plasma NE levels in the patients with ruptured intracranial aneurysms were significantly higher than those in the patients with brain tumors and non-neurological diseases. Plasma E levels in the patients with intracranial aneurysms were also higher than the concentrations in the patients with brain tumors and non-neurological diseases.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[A study on changes of plasma catecholamines concentrations and clinical prognosis in patients with ruptured intracranial aneurysms]. 646 55

Calcium ion (Ca++) plays a central role in excitation-contraction coupling of both cardiac and vascular smooth muscles and have important functional interactions with other cations, including sodium, potassium, and magnesium. Ca++ transients associated with contraction-relaxation cycles of the heart and vasculature can now be recorded directly by use of aequorin, a bioluminescent protein that emits light when it combines with Ca++. After microinjection or chemical loading of aequorin into the sarcoplasm, light output provides an index of intracellular [Ca++]. In cardiac muscle, intracellular Ca++ increases more quickly than tension and decreases toward basal levels by the time peak tension is reached. The calcium transients of working myocardium in both human subjects and other mammalian species appear to be dominated by the release and uptake of Ca++ from intracellular stores under all conditions studied. Drugs and disease states produce marked changes in the amplitude and time course of the Ca++ transient and the corresponding contractile response. In vascular smooth muscle, there are stimulus-specific patterns in intracellular Ca++ associated with tonic contractions. Although Ca++ is related to tension development, the relationship appears to be more complex than that in cardiac muscle. As a result, tension development cannot be used as an index of free Ca++ levels in vascular smooth muscle. Selection of the most effective therapy to reverse a tonic contraction in states of spasm or hypertension may depend on the specific stimulus that caused the increased tone.
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PMID:Calcium and cardiovascular function. Intracellular calcium levels during contraction and relaxation of mammalian cardiac and vascular smooth muscle as detected with aequorin. 649 58

Cortical blindness without retinal changes is a rare complication in preeclampsia. We report two patients, both of whom developed cortical blindness one and two days post partum. In one of these patients, the blindness occurred following eclamptic seizure. In both patients the total blindness recovered fully after two and three days respectively following treatment for hypertension and cerebral edema. Spasm of small vessels in the occipital cortex is assumed to be the cause of this complication.
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PMID:[Postpartum amaurosis in patients with pre-eclampsia]. 668 42

Ten adult cats were anesthetized and ventilated by respirator. After the basilar artery was exposed transclivally and visualized with an operative microscope, mean arterial blood pressure (MABP) was raised gradually by intravenous drip infusion of norepinephrine (5-20 micrograms/kg) or angiotensin-II-amide (0.3-1.0 micrograms/kg). At various blood pressures, microphotographs were taken. There was no appreciable change in vessel diameter at a MABP ranging from 78 to 191 mmHg. The blood pressure was allowed to return to the initial baseline level. Arterial spasm was produced by the topical application of 0.2 M calcium gluconate, which decreased the arterial diameter by 13 to 58 percent for more than 60 min. Blood pressure was increased again after the production of the arterial spasm. Significant increases in the diameter of the arteries were produced by the drug-induced hypertension at levels of MABP ranging from 82 to 192 mmHg. The maximum arterial dilations ranged from 123 to 208 percent of the untreated control. The degree of dilation of the arteries almost paralleled the rise in MABP. Norepinephrine and angiotensin-II had a similar effect on both the blood pressure and the arterial diameter. Induced hypertension would be expected to improve blood flow parameters in the case of spastic cerebral arteries.
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PMID:Effect of induced hypertension on experimentally-induced cerebral arterial spasm. 673 Oct 26

Latrodectus mactans has now invaded towns and cities. The spider's venom is a neurotoxin that causes little local reaction but produces pain and spasm in large skeletal muscle groups within 30 minutes to three hours after the bite. Severe envenomation may result in respiratory failure and coma. First aid is of no value. Muscle relaxants are useful in treatment, as is calcium gluconate. Antivenin is indicated for high-risk victims, such as those with hypertension and persons younger than 16 or older than 60 years of age.
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PMID:Black widow spider bite. 673 Dec 42

The results of operation have been analysed in 182 patients with 219 intracranial arterial aneurysms. One hundred and sixty of the aneurysms had ruptured; for 150 "typical" supratentorial aneurysms, the operative case fatality rate was 10%, and a satisfactory outcome was obtained in 85%. There were no deaths and little morbidity in 108 operations on grade 0 or 1 patients. Among a number of factors influencing outcome, the most obvious were age, hypertension, cerebral arterial spasm, and the clinical condition of the patient at the time of operation. The timing of surgery had no effect on results.
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PMID:Surgery for cerebral aneurysms. An eight-year experience. 673 4

The role of calcium in the cardiovascular system, and the pharmacology, pharmacokinetics, and studies evaluating the clinical use of three calcium-channel blocking agents--verapamil hydrochloride, nifedipine, and diltiazem hydrochloride--are reviewed. Inhibition of calcium conductance and alteration of calcium availability cause profound changes in: slow inward current of the cardiac action potential, myocardial contractility and metabolism, blood pressure regulation, and smooth-muscle activity. Calcium-channel blocking agents affect the movement of calcium through these channels in smooth and cardiac muscle; the specific agents in this class differ markedly in their inhibitory effects. Verapamil hydrochloride is useful intravenously for treating supraventricular rhythm disturbances. It is absorbed well when taken orally, but there is an extensive first-pass effect, so that about 20% enters the systemic circulation. The incidence of side effects in patients receiving verapamil is 9-10%; about 1% require discontinuation of therapy. Verapamil is contraindicated in patients with sinus-node disease, unstable atrioventricular block, and shock. Nifedipine has proven useful for hypertension, coronary-artery spasm, and exertional angina; it has little negative inotropic effect. Approximately 90% of an oral dose is absorbed, and 65-70% reaches the systemic circulation after first-pass metabolism. Protein binding of nifedipine ranges from 92 to 98%. Side effects of nifedipine, usually associated with the peripheral vasodilatory action, occur in approximately 15% of patients, requiring discontinuance in 2-5%. Diltiazem hydrochloride has been shown effective in the treatment of coronary-artery spasm; limited studies indicate it may be useful in treating exertional angina, hypertension, and possibly arrhythmias. Diltiazem's oral bioavailability is good (90% reaches systemic circulation), but there is significant interindividual variability between administered dose and resulting plasma concentration. Geriatric patients have delayed absorption and reduced clearance of diltiazem given in sustained-release tablets. Studies of diltiazem are limited at this time. The exact role of calcium-channel blocking agents has not yet been elucidated. However, their ability to influence the calcium channel greatly expands the therapeutic armamentarium for cardiovascular disease and other disorders.
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PMID:Calcium-channel blocking agents. 676 59


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