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

Systemic hypertension occurs in more than one third of patients having coronary artery bypass graft (CABG) operations. This report describes our studies in 100 consecutive patients undergoing CABG. We found that certain preoperative clinical, angiographic, and biochemical factors predispose to the development of perioperative hypertension. These included a well-documented history of hypertension, an elevated blood pressure the day prior to operation, greater than 50 percent obstruction of the left main coronary artery, and increased levels of dopamine beta hydroxylase (DBH). The hemodynamic pattern of perioperative hypertension was that of an increased systemic vascular resistance which was associated with increased levels of plasma catecholamines and plasma renin activity (PRA). Nitroprusside was shown to be effective in managing CABG hypertension, although other, more specific therapy may be preferable.
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PMID:Systemic hypertension associated with coronary artery bypass surgery. Predisposing factors, hemodynamic characteristics, humoral profile, and treatment. 30 28

Myocardial performance in the immediate postoperative period was studied 49 cardiac surgical patients treated with nitroprusside alone. With a thermodilution catheter positioned in the pulmonary artery, cardiac output was calculated and cardiac index, systemic vascular resistance index, and stroke work index were derived before after treatment with nitroprusside. The drug was a administered to all patients because of elevated systemic vascular resistance index. Based on their mean arterial pressure and cardiac index before treatment, the patients fell into two groups. Group I patients (N = 25) had elevated mean arterial pressure and normal cardiac index. Group II patients (N = 24) had normal mean arterial pressure and subnormal cardiac index. Nitroprusside administration resulted in a significant reduction of systemic vascular resistance index in all patients. In Group I the mean arterial pressure was lowered significantly while cardiac index increased only slightly. In Group II there was no change in arterial pressure, but cardiac index improved significantly. The results not only confirm that nitroprusside is effective in managing postoperative hypertension, but also demonstrate that in patients with postoperative left ventricular failure, the drug can improve cardiac output by reducing systemic vascular resistance without significantly lowering arterial blood pressure.
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PMID:Improved myocardial performance in postoperative cardiac surgical patients with sodium nitroprusside. 64 13

Nitroprusside was used with intermittent hemodialysis over a 26-day period in a 6-year-old boy with intractable hypertension. Hemodialysis effectively removed thiocyanate from the blood, thus preventing its accumulation and subsequent toxic manifestations. Prolonged nitroprusside infusion maintained arterial blood pressure at acceptable levels until the patient became responsive to other antihypertensive therapy.
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PMID:Prolonged nitroprusside and intermittent hemodialysis as therapy for intractable hypertension. 71 10

A young footballer with phaeochromocytoma showed classical exercise-induced symptoms. Noradrenergic clincial phenomena suggested an extra-adrenal site. The usefulness of urine metabolite estimation and of localizing procedures and the importance of preoperative alpha and beta blockade are stressed. Nitroprusside was used successfully to control hypertension during surgery. Unexplained fever after operation is reported.
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PMID:Phaeochromocytoma in a footballer. 86 70

Five hypertensive patients with acute myocardial infarction and persistent postinfarction hypertension who experienced severe and recurrent resting chest pain, ST elevations, and severe ventricular arrhythmias refractory to conventional treatment with bed rest, sedation, oxygen inhalation, nitrates, and antiarrhythmic agents received sodium nitroprusside by continuous intravenous infusion, titrated to reduce systolic blood pressure to 100 to 110 mm Hg. Treatment resulted in noticeable improvement in symptoms, reduction in ST elevations, and abolition of ventricular arrhythmias in all five patients. In four patients, cessation of nitroprusside infusion after 48 hours resulted in prompt recurrence of hypertension, chest pain, ST-segment elevations, and ventricular arrhythmias. These were all rapidly reversed following reinstitution of the nitroprusside therapy for seven to eight days, strongly suggesting a cause-and-effect relationship. Nitroprusside infusion in these patients suggests a potentially important use for such therapy in this clinical setting.
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PMID:Nitroprusside therapy. Treatment of hypertensive patients with recurrent resting chest pain, ST-segment elevation, and ventricular arrhythmias. 94 46

Among the accepted advantages of general anesthesia in ophthalmic surgery is improved control of intraocular pressure (IOP). Although standard textbooks advocate deliberate arterial hypotension to facilitate intraocular surgery by reducing IOP, scientific proof of such an effect is lacking. The authors investigated effects of induced arterial hypotension on IOP in an anesthetized porcine model. Forty-two piglets were anesthetized with piritramide, were placed in the prone position, and had the anterior chamber of one eye punctured with a small Teflon cannula to measure IOP. Six pigs were used in a pilot study to establish dose-response relationships for the hypotensive agents; 36 pigs were randomly allocated to one of three groups (n = 12) to receive nitroprusside, adenosine, or isoflurane to reduce mean arterial pressure (MAP) by 50%. Measurements were made after initial stabilization of hemodynamic variables and IOP (control), when a stable MAP of 0.5x control was maintained for 10 min or longer, and after return of MAP to a posthypotensive steady state. The median of differences between time intervals was analyzed statistically for all variables. Nitroprusside and adenosine produced hyperdynamic hypotension (cardiac index increased); isoflurane-induced hypotension was hypodynamic. Control IOPs were 12.9, 12.5, and 11.1 mmHg in the nitroprusside, adenosine, and isoflurane groups, respectively. Median change in IOP during hypotension was -1.5, +1.5, and 0 mmHg in the nitroprusside, adenosine, and isoflurane groups, respectively. The IOP during adenosine-induced hypotension was significantly higher than that during either nitroprusside- or isoflurane-induced hypotension. Return of MAP to control levels was frequently associated with intraocular rebound hypertension when arterial hypotension had been induced with adenosine or nitroprusside.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Deliberate arterial hypotension does not reduce intraocular pressure in pigs. 151 91

Although endothelium-derived prostaglandin I2 stimulates renin release, exogenous endothelium-derived relaxing factor (EDRF) can inhibit it. To characterize the role of EDRF as an endogenous regulator of renin release, we inhibited or stimulated its production in rat renal cortical slices in vitro. Renin concentration in the incubation medium was determined by radioimmunoassay for angiotensin I (Ang I) generation. NG-Monomethyl-L-arginine (LNMMA) (10(-4) M), which blocks EDRF formation, significantly enhanced basal renin release from kidney slices by more than 50% in control medium (40.0 +/- 14.3 ng Ang I/hr/mg/30 min; p less than 0.01) or in medium treated with 1.6 x 10(-5) M meclofenamate (50.8 +/- 8.4 ng Ang I; p less than 0.025). Isoproterenol (10(-5) M)-stimulated renin release (40.0 +/- 14.3 ng Ang I; p less than 0.02) was not modified by LNMMA; addition of L-arginine (10(-5) M), the precursor of EDRF, did not change basal but blocked isoproterenol stimulation of renin. Nitroprusside (10(-5) M) completely reversed melittin-stimulated renin release. Endothelin-1, an endothelium-derived vasoconstrictor, inhibits renin release and stimulates EDRF and prostaglandin synthesis. To determine whether any of the renin-inhibiting effect of endothelin-1 was due to its stimulation of EDRF, we compared the effect of endothelin-1 on cortical slices with and without EDRF inhibition. Endothelin-1 (10(-7) M) decreased renin by 36.7 +/- 10.9 ng Ang I (p less than 0.01) compared with controls, and the response was the same after either LNMMA or hemoglobin treatment.(ABSTRACT TRUNCATED AT 250 WORDS)
Hypertension 1992 Feb
PMID:Nonprostanoid endothelium-derived factors inhibit renin release. 173 97

Regional spillover of norepinephrine (NE), based on isotope dilution and single-compartment steady-state kinetics, is considered one of the best parameters for estimating organ sympathetic activity. However, the effects of local changes in clearance of NE on the spillover have not yet been investigated. We studied local NE kinetics and clearance in the forearm of 10 healthy subjects using intra-arterial infusions of NE, tritiated NE, the neuronal uptake inhibitor desipramine, and tyramine, which competes with NE for the neuronal uptake carrier. Before and during complete blockade of neuronal uptake by desipramine the venous concentration-time curves for tritiated NE and for NE released by tyramine were biexponential, consistent with the presence of (at least) two compartments for circulating tritiated NE and for locally released NE. The time constants for tyramine-induced release of NE and, in the same subjects during desipramine infusion, for tritiated NE were almost equal at the same level of forearm blood flow. This argues against possible diffusion or transport differences for NE to and from the circulation and the synapse. The regional intrinsic clearance capacity (a measure of the maximal ability of an organ to irreversibly remove drug by all pathways in the absence of any flow limitations) for NE decreased in the forearm by 65% (p less than 0.01) during neuronal uptake blockade by desipramine; the forearm clearance decreased by 59% (p less than 0.001), whereas the spillover rate of NE increased from 33 +/- 5 to 63 +/- 11 pmol.min-1 (p less than 0.05). Nitroprusside-induced increments in blood flow increased the spillover of NE from 18 +/- 4 to 35 +/- 6 pmol.min-1 (p less than 0.01); the clearance of circulating NE also increased (by 58%, p less than 0.05), and the intrinsic clearance capacity remained unchanged. This demonstrates that regional spillover of NE is markedly influenced by local changes in clearance and flow. The new parameter plasma appearance rate of NE is proposed. Although also derived from isotope dilution, this parameter may better approximate the regional entry of NE into the blood pool than spillover. This is corroborated by the nonsignificant changes of plasma appearance rate of NE during our desipramine and nitroprusside infusions.
Hypertension 1991 Jul
PMID:Does regional norepinephrine spillover represent local sympathetic activity? 186 Jul 12

In severe preeclampsia, short-term peripartum management of hypertension with hydralazine is complicated by relatively prolonged hypotensive episodes, resulting in fetal distress. We hypothesized that nitroprusside's rapid onset and brief antihypertensive action would permit more controlled blood pressure reduction. Nitroprusside was infused into 10 invasively monitored subjects until mean arterial pressure either 1) was gradually reduced 10-20% or 2) fell abruptly. Subjects fell into two groups, defined by whether the hypotensive effect of nitroprusside was accompanied by a fall in heart rate (group A, n = 8) or a rise (group B, n = 2). Group B showed the expected sinoaortic baroreceptor reflex elevations in heart rate (+17 +/- 6 beats/min) in response to moderate falls in mean arterial pressure (-32 +/- 9 mm Hg) elicited by moderate doses (1.03 +/- 0.23 micrograms/kg/min). However in group A, steep reductions in mean arterial pressure (-75 +/- 22 mm Hg, p less than 0.0001), significantly greater than in group B (p less than 0.05), occurred at much lower doses (0.35 +/- 0.23 micrograms/kg/min; p less than 0.05) and were accompanied by falls in heart rate (-21 +/- 7 beats/min). The apparently paradoxical falls in heart rate and extreme hypotensive responses in group A indicate severe circulatory compromise, corresponding to the cardiac and vasomotor depression that characterizes severe hemorrhage and other forms of acute/severe hypovolemic hypotension. This hemodynamic pattern represents a cardiopulmonary baroreceptor reflex presumably related to the Bezold-Jarisch reflex. The appearance of this pattern in the present study probably reflects the imposition of nitroprusside's prominent venous dilator action on the relatively reduced blood volume that generally characterizes severe preeclampsia.
Hypertension 1991 Jul
PMID:Nitroprusside in preeclampsia. Circulatory distress and paradoxical bradycardia. 186 Jul 15

Paraplegia is a devastating complication of surgery on the descending thoracic aorta. During surgical repair, the aorta is cross-clamped, and nitroprusside is often used to treat arterial hypertension that can occur above the cross-clamp. Twenty-one dogs were studied to determine the effects of nitroprusside on intraspinal pressures, mean aortic pressures below the cross-clamp, and spinal cord perfusion pressure. Perfusion pressure in spinal radicular arteries originating below the aortic cross-clamp was estimated as the distal aortic pressure minus intraspinal pressure. Nitroprusside was used to return the mean arterial pressure above the cross-clamp to values similar to the pre-cross-clamp levels in 7 dogs. Fourteen animals did not receive sodium nitroprusside. Aortic cross-clamping resulted in small but significant increases in intraspinal pressure (4.3 +/- 0.8 to 7.5 +/- 0.9 mm Hg in non-nitroprusside-treated dogs, and 3.4 +/- 1.0 to 5.6 +/- 1.5 mm Hg in the nitroprusside group before nitroprusside). Nitroprusside caused a further increase in intraspinal pressure (5.6 +/- 1.5 to 8.3 +/- 2.2 mm Hg) and a decrease in aortic pressure below the cross-clamp (26 +/- 5 to 18 +/- 4 mm Hg). The increase in intraspinal pressure and the decrease in aortic pressure below the cross-clamp after nitroprusside resulted in a decrease in spinal cord perfusion pressure from 19 +/- 5 mm Hg to 11 +/- 4 mm Hg. Because nitroprusside decreases spinal cord perfusion pressure and may increase the risk of spinal cord ischemia, the avoidance of large doses of nitroprusside to arbitrarily return mean arterial pressure above the cross-clamp to pre-cross-clamp levels is recommended.
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PMID:Sodium nitroprusside decreases spinal cord perfusion pressure during descending thoracic aortic cross-clamping in the dog. 213 65


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