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

The effects of nitroprusside, nitroglycerin and phentolamine on cardiac dynamics and on the fraction of cardiac output shunted through systemic arteriovenous communications, which may explain disparate responses elicited by these systemic vasodilators upon venous return, have been studied in 15 nonanesthetized dogs. Cardiac dynamic parameters were measured by electromagnetic flow probe placed at the root of the aorta. Quantitative measurements of total systemic arteriovenous shunting were determined from the fraction of 9 mu radioactively labeled microspheres, injected into the left atrium, recovered in the pulmonary artery. To provide a common basis for comparison, the mean arterial pressure was lowered by 15-20% either with an intravenous infusion of nitroprusside, nitroglycerin or phentolamine. At the fifteenth minute of infusion, nitroprusside produced significant decrease in stroke volume index (23%) and left ventricular power and work (28% and 40%). Nitroglycerin decreased significantly stroke volume index (12%), cardiac index (9%) and left ventricular work (22%). Phentolamine significantly increased heart rate (72%) and left ventricular maximum acceleration (30%) while it decreased stroke volume index (41%), left ventricular power and work (19% and 55%). Total peripheral resistance was significantly affected only by infusion of phentolamine (-18%). Left ventricular maximum velocity, mean systolic ejection rate and maximum systolic flow did not change significantly under infusion of these systemic vasodilators. Under control conditions, total systemic shunting of cardiac output averaged 8.9-10% and was not modified by any of the vasodilators used. Arteriovenous O2 difference and oxygen consumption, corroborated these findings since they remained within normal limits before and after infusion of nitroprusside, nitroglycerin or phentolamine.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Hypotension and arteriovenous shunting: effects of intravenous infusion of nitroprusside, nitroglycerin and phentolamine. 642 Dec 4

We examined the effect of parenteral phentolamine in 11 critically ill patients with a low cardiac output state and a high systemic resistance. Because vasodilators often affect left ventricular end-diastolic pressure-volume relationships (compliance) in acute cardiac disease, changes in the pulmonary capillary wedge pressure (WP) may conceivably not reflect the true effect of vasodilators on left ventricular preload. Hence, we measured left ventricular ejection fraction (LVEF) with ECG-gated cardiac scintigraphy and stroke volume by thermodilution before and during phentolamine infusion. We then calculated left ventricular end-diastolic volume index (LVEDVI). Phentolamine infusion was associated with an increase in the mean cardiac index (CI) (1.96 +/- .53 [mean +/- SD] to 2.45 +/- .69 L/min X m2; p less than .0025) whereas the mean WP fell (19.5 +/- 7.5 to 13.5 +/- 7.3 mm Hg; p less than .05). There was no simultaneous change in the mean LVEDVI (100 +/- 48 to 110 +/- 40 ml/m2; p = NS), implying that one of the effects of phentolamine infusion was to improve left ventricular diastolic compliance. Multiple regression analysis suggested that the major effect of phentolamine on stroke volume was mediated by concomitant changes in the LVEDVI (r2 = .64). Therefore, benefit from phentolamine in low cardiac output states is multifactorial and phentolamine likely improves left ventricular compliance in some patients.
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PMID:Phentolamine in low cardiac output states: an assessment with ECG-gated cardiac scintigraphy. 661 15

Aortic rigidity, plasma noradrenaline and adrenaline, and hemodynamic parameters were measured in 48 essential hypertensive patients, 25 younger than 45 (Group I) and 23 of 45 years and over (Group II). Aortic rigidity was determined by the ratio of pulse pressure over stroke volume. Aortic rigidity and hemodynamic parameters were also determined after combined alpha-beta receptor blockade induced by Labetalol (mg 100 IV) or by Propranolol (mg 10 IV) plus Phentolamine (mg 10 IV). The aortic rigidity index was significantly higher in Group II, systolic arterial pressure being significantly higher. All other data, including plasma noradrenaline and adrenaline, were not significantly different in the two groups. In Group II a significant correlation (r = 0.62) was noted between aortic rigidity indexes and plasma noradrenaline values. The alpha-beta receptor blockade induced a decrease of aortic rigidity particularly in Group II, owing to a more marked decrease of systolic arterial pressure. A highly significant correlation was noted in Group II between the changes in aortic rigidity index and the basal plasma noradrenaline levels (r = 0.81). Therefore, the aortic rigidity in essential hypertensive patients older than 45 is influenced by the sympathetic nervous system activity, as judged by plasma noradrenaline levels. This influence seems related to an increase with age of aortic responsiveness to sympathetic stimulation.
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PMID:Aortic rigidity and plasma catecholamines in essential hypertensive patients. 711 58

Basal hemodynamics and plasma catecholamines were measured in 10 patients with systolic hypertension, 7 males and 3 females, aged 38-69 years (Group 1), and in 10 patients with systolic and diastolic hypertension, 7 males and 3 females, aged 40-65 years (Group 2); the same measurements were repeated after acute pharmacological alpha and beta-blockade with Labetalol, 100 mg iv, or Propranolol, 10 mg iv, plus Phentolamine, 10 mg iv. In patients of Group 1 plasma noradrenaline was inversely related to systolic arterial pressure and to stroke index and was directly related to heart rate. In patients of Group 2 plasma noradrenaline was directly related to systolic arterial pressure. After acute alpha and beta-blockade the degree of reduction of systolic arterial pressure was directly related to basal plasma noradrenaline in both groups; systolic arterial pressure was reduced to normotensive levels in 5 patients of Group 1 who had high basal plasma noradrenaline values. These results confirm some of our previous findings and suggest that in some patients with systolic hypertension adrenergic activity is increased and may have a significant role in maintaining high blood pressure values.
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PMID:Adrenergic activity in systolic hypertension. 711 59

Vagal control of pyloric resistance was evaluated in anesthetised pigs by recording gastropyloroduodenal motility and transpyloric flow during emptying of a liquid nonnutrient meal. Vagotomy did not modify pyloric resistance or the characteristics of the flow pulses. Electrical stimulation of the distal stumps of cervical or thoracic vagus nerves decreased pyloric resistance and triggered flow pulses of large stroke volume. This was associated with increased fundic tone and pressurization of the antrum. Phentolamine but not propranolol reduced the responses to vagal stimulation. These observations demonstrate that reduced pyloric resistance is one mechanism by which vagal activation promotes transpyloric flow.
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PMID:Vagal control of transpyloric flow and pyloric resistance. 799 10

In a series of 12 cases of pheochromocytoma, 11 patients were clinically cured by operation and one died of malignant tumor. It has been reported that of patients presenting with hypertension, 0.5 to possibly 2 per cent will be found to have pheochromocytoma. This small group of patients will have a good chance of cure of hypertension by surgical removal of the tumor. Hypertension and manifestations of hypermetabolism are classically seen in pheochromocytoma, but these symptoms vary, and hypertension may be entirely absent. Hypertension which is no longer dependent on pressor amines may result after prolonged circulation of pressor substances in the bloodstream. The quantity and proportion of the pressor amines in the circulation are largely responsible for the variable clinical picture. The Regitine(R) test is an excellent screening test but is not absolutely specific for pheochromocytoma. The histamine test should not be employed in patients whose blood pressure exceeds 160/110 mm. of mercury, lest it set off cerebrovascular accident.A modification of the Garlock transdiaphragmatic incision that was used in the present series of cases affords unparalleled exposure and facility in the removal of pheochromocytoma.
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PMID:Pheochromocytoma--a report of 12 cases. 1385 59

Ten normotensive patients diagnosed as having a CVA had Regitine tests and urinary VMA and catecholamine determinations during the first day of hospitalization. The VMA and catecholamine levels were all within normal limits (except for one elevated VMA level) but did not correlate well with each other. The average response to phentolamine was an average drop in blood pressure of 30mm. Hg systolic and 19 mm. Hg diastolic. Mechanisms by which hypertensive states or cerebral damage might effect blood pressure are discussed. It is suggested that CNS damage might induce a vasolabile or hypersensitive state via connections and consequent alterations in the autonomic vasomotor system.
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PMID:Phentolamine tests and catecholamine levels in normotensive CVA patients. 1789 60


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