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

The hemodynamic effects of dihydralazine and prazosin (0.1 and 1.0 mg/kg i.v.) on the circulatory system and left ventricular dynamics and contractility has been performed in 10 purebred beagle dogs (15.5 +- 1.4 kg) under pentobarbital sodium (35-40 mg/kg i.p.) anaesthesia by means of thermodilution and catheter technics. The changes of cardiovascular values were: 1. Either dihydralazine and prazosin decreased mean arterial blood pressure in the dose of 0.1 mg/kg i.v. Following application of 1.0 mg/kg intravenously, the arterial pressure abruptly decreased after prazosin. 2. Both pharmaca caused tachycardia. Being slowly introduced but continued by dihydralazine, the increase of pulse rate after prazosin was only initial. 3. The cardiac dynamics were differently influenced by dihydralazine and prazosin. In the estimated dose range prazosin led to an increase of cardiac output directly after application while dihydralazine induced a gradual enhancing of cardiac output. 4. The stroke volume was decreased by prazosin and slightly increased by dihydralazine. 5. While distinctly decreasing initially after prazosin, peripheral total resistance was slowly reduced by dihydralazine. 6. The contractility of the left ventricle, estimated as dp/dtmax and VCE, showed a distinct increase of the myocardial inotropy after both compounds. The maximal effect after prazosin, however, was to be seen immediately post applicationem. Dihydralazine led to a deferred enhancing of the measured contractility parameter.
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PMID:[Dihydralazin versus prazosin. The hemodynamic effect of the modul substances (author's transl)]. 60 53

Dihydralazine, given in small i.v. doses, has been of great value in diagnostic tests for unilateral renovascular hypertension, where it enhances renin release on the affected side. The acute hemodynamic effects of an i.v. dose of 0.1 mg/kg b.wt. were studied in 14 patients with essential hypertension, using a quantitative renographic technique for determination of effective renal plasma flow and radiocardiographic technique for determination of the parameters in systemic circulation. Cardiac index increased from 4.040 to 6.423 1/min.m2 (p less than 0.01), stroke index from 59 to 66 ml/beat.m2 (p less than 0.05), heart rate from 70.4 to 96.6 beats/min (p less than 0.01) and left ventricular work index from 1.04 to 1.49 W/m2 (p less than 0.01), while mean arterial B decreased from 125 to 110 mmHg (p less than 0.01) and total peripheral resistance index from 2927 to 1534 10(5).N.s.m(-3) (p less than 0.01). Effective renal plasma flow and pulmonary plasma volume were unchanged. Peripheral renin activity increased from 0.5 to 1.6 nmol A1/1.h (p less than 0.02). It is concluded that even a small test dose of 0.1 mg/kg of dihydralazine elicits a considerable additional work load on the heart, a circumstance that must be taken into consideration in studies of patients with coronary heart diseases.
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PMID:The cardiac response to a small i.v. dose of dihydralazine, a safe drug for diagnostic tests? 66 11

The cerebrovascular effects of graded, controlled dihydralazine-induced hypotension were studied in rats with renal hypertension (RHR) and spontaneous hypertension (SHR). Repeated measurements of cerebral blood flow (CBF) were made using the intraarterial 133Xenon injection technique in anaesthetised normocapnic animals. Dihydralazine was administered in single increasing i.v. doses (0.1 to 2 mg/kg), and CBF measured after each dose when a stable blood pressure had been reached. From a resting level of 145 +/- 7 mm Hg in RHR and 138 +/- 11 mm Hg in SHR, mean arterial pressure (MAP) fell stepwise to a minimum of around 50 mm Hg. CBF was preserved during dihydralazine induced hypotension, and remained at the resting level of 79 +/- 13 ml/100 g . min in RHR and 88 +/- 16 ml/100 g . min in SHR. Following 2 hours hypotension at the lowest pressure reached, the rats were sacrificed by perfusion fixation and the brains processed for light microscopy. Evidence of regional ischaemic brain damage was found in 4 of 11 animals: in 2 cases the damage appeared to be accentuated in the arterial boundary zones. Although the lower limit of CBF autoregulation in these rats is around 100 mm Hg during haemorrhagic hypotension, dihydralazine brought MAP to around 50 mm Hg without any concomitant fall in CBF. This was interpreted as being due to direct dilatation of cerebral resistance vessels. The combination of low pressure and direct dilatation may have resulted in uneven perfusion, thus accounting for the regional ischaemic lesions.
Stroke
PMID:Cerebral blood flow during dihydralazine-induced hypotension in hypertensive rats. 669 14

In 32 neurosurgical patients in neuroleptanaesthesia and controlled hypotension the following hemodynamic parameters were studied. Blood pressure, heart rate, cardiac output in addition serial measurements of the blood gasanalysis, oxygen content were performed from the arterial and centralvenous blood samples. In the first collective of 12 patients a mean dosis of 45 +/- 12 mg dihydrazinophthalazine (Nepresol) decreased the blood pressure to a mean value of 55 +/- 7 mm Hg. In spite of this blood pressure drop the cardiac output increased by 62,4% in consequence to the increase of the heart rate by 27% and the stroke volume by 19,9%. A controlled hypotension to a mean value of 57 +/- 9 mm Hg was performed in 20 patients with sodiumnitroprusside. In contrast to the effects of Nepresol after medication of sodiumnitroprusside the cardiac output decreased by 16% the stroke index by 24% while the heart rate increased by 18%. Both drugs have a useful place in neuroanesthesia, but sodiumnitroprusside is the drug of choice for controlled hypotension, because after medication of Nepresol even in the higher dose range there is no dose-response-relationship and the onset of action is delayed.
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PMID:[Circulatory effects of dihydrazinophthalazine (Nepresol) compared with sodium nitroprusside in controlled hypotension. A study of neurosurgical patients under neuroleptanesthesia]. 677 47

Hypertension is the most common medical complication of pregnancy in South Africa and a major cause of maternal and perinatal morbidity and mortality worldwide. At King Edward VIII Hospital in Durban, 18% of all admissions to the obstetric unit have some degree of high blood pressure. Hypertension in its most severe form produces convulsions, proteinuria, and edema and may lead to fetal and maternal death. High-risk groups for preeclampsia are teenage mothers, primigravidas, and women with a history of elevated blood pressure, previous preeclampsia, molar pregnancies, multiple pregnancies, or hydrops fetalis. Methods used to prevent preeclampsia include a low-salt diet supplemented with calcium, magnesium, zinc, fish, and pharmacological manipulation. In developing countries, prevention and detection of preeclampsia is difficult since women seek antenatal care late in their pregnancies. In Durban, the average gestational age at first antenatal attendance is 28 weeks, and 80% of patients presenting with eclampsia have defaulted antenatal care. Treatment includes admission to hospital to establish the etiology of the hypertension and maternal renal function tests . Fetal condition is a sensitive index of hypertension and is judged by 1) clinical evidence of fetal growth, 2) weekly antepartum cardiotocography, and 3) ultrasonographic screening. Patients are managed according to three clinical groups: 1) those identified before 36 weeks, 2) those identified after 36 weeks, and 3) patients in hypertensive crisis. Dihydralazine is the drug of choice for imminent eclampsia. If the patients has a ripe cervix, delivery is induced with 6-8 hours. Steroid contraception use in the older hypertensive patient should be avoided because of possible development of atherosclerosis and stroke. Puerperal tubal ligations in the hypertensive patient ought to be avoided because of the risks of thromboembolic phenomena and pulmonary embolism. Methyldopa is the treatment of choice in cases of moderate to severe hypertension. Intravenous dihydralazine is relatively safe for the rapid reduction of high blood pressure.
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PMID:Coping with hypertension in pregnancy. 1234 38