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

This paper describes the performance of a microfiltration plasmapheresis unit operating with reversing oscillatory flows. The device consists of a flat channel duct between cellulose nitrate membranes and was used to extract plasma from anticoagulated fresh whole bovine blood. Measurements were made of plasma flux, haematocrit concentration, haemolysis and protein sieving coefficients. The effects on plasma flux are reported for alterations in the stroke and frequency of flow pulsations, transmembrane pressure, membrane properties and blood throughput. It was found that the imposition of oscillatory flows enhanced the plasma extraction rate by a factor of 3, producing about 0.9 litre/min/m2 membrane.
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PMID:Separation of plasma from whole blood by membrane filtration in oscillatory flows. 378 1

We compared the short-term hemodynamic effects of isosorbide dinitrate (40 mg orally) and captopril (25 mg orally) in 18 patients with severe chronic heart failure in a randomized, crossover study conducted on consecutive days. Captopril and isosorbide dinitrate produced similar decreases in systemic vascular resistance, but whereas nitrate therapy decreased pulmonary arteriolar resistance significantly, captopril did not; the difference between the two drugs was highly significant (-25% vs -5%, p less than 0.001). Left ventricular filling pressures declined similarly with both captopril (-10.5 mm Hg) and with isosorbide dinitrate (-9.3 mm Hg), but because pulmonary arteriolar resistance fell significantly with nitrate therapy, mean right atrial pressure decreased more with isosorbide dinitrate than with captopril (-5.4 vs -2.8 mm Hg, respectively; p less than 0.001). Although systemic resistance declined similarly with both drugs, cardiac index increased more with nitrate therapy than during converting-enzyme inhibition (+0.47 vs +0.23 L/min/m2) (p less than 0.01), and therefore mean arterial pressure fell less with isosorbide dinitrate than with captopril (-10.5 mm Hg vs -16.7 mm Hg); p less than 0.05); two patients developed symptomatic hypotension with captopril, whereas none did so with the nitrate. The difference in the effects of the two drugs on cardiac index was not due to differences in their effects on heart rate, since heart rate fell similarly with both drugs, and thus both drugs produced similar increases in stroke volume index. These data indicate that, in patients with severe chronic heart failure, nitrates exert favorable dilating effects on the pulmonary circulation not shared by captopril.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Comparative effects of captopril and isosorbide dinitrate on pulmonary arteriolar resistance and right ventricular function in patients with severe left ventricular failure: results of a randomized crossover study. 389 May 6

The use of nitrates in various sublingual, oral, topical and intravenous forms of treatment of patients with congestive heart failure (CHF) is based on their efficacy in dilating capacitance vessels and reducing elevated ventricular diastolic pressure on both the left and right sides of the heart. Their modest arteriolar and arterial dilating effect may also decrease aortic impedance and produce a slight increase in stroke volume despite the reduction in preload. This favorable hemodynamic response requires relatively large doses of the nitrates but these doses are remarkably well tolerated in the majority of patients with CHF. In chronic CHF there has been evidence from small controlled trials of clinical efficacy (increased exercise tolerance and reduction in symptomatology) as well as hemodynamic efficacy. The combination of nitrates with a more potent arteriolar dilator such as hydralazine or minoxidil has produced a more striking acute hemodynamic benefit. Long-term response to such combined therapy is currently the subject of a Veterans Administration cooperative study. The current recommended approach to nitrate therapy in patients with CHF is to use the dosage necessary to normalize ventricular filling pressure. This can be best assessed in the clinic by monitoring jugular venous pressure. This response often requires dosages of isosorbide dinitrate of 160 to 320 mg daily. Transdermal preparations of nitroglycerin may give more constant blood levels but a large dosage is usually required to produce a sustained hemodynamic effect (40 to 80 cm2).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Nitrates for congestive heart failure. 401 49

The following hemodynamic parameters were measured at rest and 1, 2, 4, 6, 8, 12 and 24 hours after 100 mg of ISDNSR p.o. in 10 patients with dilated cardiomyopathy (NYHA class III-IV): mean pulmonary artery, pulmonary capillary wedge (PCW) and arterial pressures (AP), and cardiac output (thermodilution). Plasma levels of ISDN were determined by capillary gas chromatography at the same intervals and correlated with the hemodynamic changes. PCW fell from 24 +/- 1.5 (SE) to 18 +/- 1.8 mm Hg after 1 hour (p less than 0.05) and after 2 hours to 16.9 +/- 1.6 mm Hg. This change was sustained for 8 hours. At 12 hours PCW had increased again to 21 +/- 1.5 mm Hg and at 24 hours to 22 mm Hg. AP dropped from 89 +/- 5 to 81 +/- 4 mm Hg at 1 hour (p less than 0.2) and remained 80-84 mm Hg for 8 hours. It returned to baseline levels at 12 hours. Heart rate, cardiac index, systemic vascular resistance, stroke index and left ventricular work index did not change significantly during the observation period. Plasma levels of ISDN remained between 3 and 12 ng/ml for 16 hours. Thus, ISDNSR is an effective long-acting nitrate preparation which reduces preload for 8-12 hours. After this interval, nitrate tolerance starts to develop.
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PMID:[Hemodynamic effects of a new long-acting isosorbide dinitrate]. 408 1

The effects of oral administration of molsidomine (50, 100 and 250 micrograms/kg) on left ventricular function, dimensions and hemodynamics were studied in chronically equipped, resting conscious dogs and compared to those of orally administered nitroglycerin (5, 10 and 20 micrograms/kg), as well as isosorbide dinitrate (50, 100 and 250 micrograms/kg). Enteral absorption of molsidomine was similar to that following intravenous administration of the compound, but was delayed in the case of both nitrates, so that restraint hemodynamic effects were noted. Molsidomine significantly decreased ventricular preload and internal heart dimensions. These effects were longer-lasting and more pronounced than those induced by either nitrate compound. Heart rate and LV dP/dtmax remained unaffected by molsidomine but increased in a dose-dependent fashion after administration of the nitrates. Left ventricular ejection phase contractility decreased with all three compounds. This effect was probably due to the reduced ventricular volumes and dimensions caused by molsidomine and isosorbide dinitrate, and to the additional tachycardia with concomitant reduction in ejection phase induced by nitroglycerin. Ejection time and stroke volume fell with all three agents but the effect occurred with a greater delay of onset and was more persistent after molsidomine. Nitroglycerin was found to increase cardiac output, initially, as a sequel of positive inotropy and chronotropy, with a subsequent decrease of cardiac output. In contrast, cardiac output fell by 28% and 30% (p less than 0.02) after administration of 250 micrograms/kg molsidomine or isosorbide dinitrate, respectively. These results suggest that molsidomine has no direct effects on myocardial hemodynamics and function in the resting, awake dog. The drug exerts its beneficial effects on heart performance by a long-lasting diminution of cardiac preload caused preferentially by dilatation of postcapillary venous vessels.
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PMID:Analysis of oral molsidomine effects on ventricular function and dimensions in the conscious dog. 640 16

The hemodynamic and hormonal responses to nitroglycerin administered transdermally in a gel-like matrix were evaluated in nine patients with severe congestive heart failure and in nine normal subjects. In normal subjects, peripheral vasodilation was accompanied by reflex sympathetic stimulation as reflected by an increase in heart rate and plasma norepinephrine. In patients with heart failure, nitroglycerin produced sustained hemodynamic effects that began 30 minutes after the application and fully persisted for at least 6 hours. A significant decrease in right and left ventricular filling pressures was associated with an increase in stroke index and a significant decrease in forearm and pulmonary vascular resistances. There was no change in heart rate and systemic arterial pressure or in plasma norepinephrine or plasma renin activity. After 24 hours, pressures had partially returned to control levels, but mean pulmonary artery pressure was still significantly lower than in the control period. After removal of the nitroglycerin, each patient exhibited a decrease in cardiac index and an increase, above the control values, in pulmonary and systemic arterial pressures and pulmonary, systemic and forearm vascular resistances. This transient rebound appeared to be unrelated to stimulation of the sympathetic or renin-angiotensin systems. Thus, transdermal absorption of this new form of nitroglycerin appears to provide a nitrate vascular effect that is sustained for 24 hours, but an endogenous vasoconstrictor effect may influence the hemodynamic response over the first 24 hours.
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PMID:Hemodynamic and hormonal response to transdermal nitroglycerin in normal subjects and in patients with congestive heart failure. 641 42

In order to test the clinically supposed development of tolerance during chronic high-dose nitrate therapy, we studied a total of 24 patients with angiographically proven coronary heart disease at rest and during ergometric exercise (supine position, 50 w for 3 min). Pulmonary arterial pressure (PAP, floating catheter), arterial blood pressure (cuff method), cardiac output (Fick principle), heart rate, and exercise capacity (w X min) were measured at rest and exercise before and during chronic (4 weeks) oral therapy with 5-isosorbide mononitrate (5-ISMN), 3 X 20 mg/day (n = 14) and 3 X 50 mg/day (n = 10). After acute administration, both doses of 5-ISMN decreased mean PAP at rest and during exercise (rest: by 25% with 20 mg and by 29% with 50 mg; exercise: by 30% with 20 mg and by 45% with 50 mg), whereas cardiac output and stroke volume were only reduced by 5-ISMN at rest. During chronic treatment with 60 mg and 150 mg 5-ISMN, and additional administration of 20 mg or 50 mg respectively lowered PAP at rest by 15% and 19%; during ergometric exercise PAP was 22% and 14% lower than during ergometry before any drug treatment. The exercise capacity slightly increased during treatment to 60 mg 5-ISMN, whereas it decreased by 25% on chronic treatment with 150 mg 5-ISMN per day. Our results show that acute administration of 5-ISMN in either dose (20 mg and 50 mg) exerts unloading effects on the heart and will increase the exercise tolerance. In contrast to the higher dose of 150 mg 5-ISMN per day, chronic treatment with the lower dose of 60 mg 5-ISMN daily will not result in drug tolerance.
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PMID:Dose dependence of tolerance during treatment with mononitrates. 666 25

The hemodynamic effects of standard dose of Nitroglycerin (NTG) ointment (23 +/- 4 mg) and oral Isosorbide Dinitrate (ISDN) 10 mg were compared in the treatment of left ventricular failure. Ten patients, 8 males and 2 females (mean age 59 +/- 9 years), affected by acute myocardial infarction (7 cases). Ischemic cardiomyopathy (2 cases) and hypertensive cardiomyopathy (1 case) were submitted to right heart catheterization by triple lumen Swan-Ganz catheter. Heart Rate (HR), mean Arterial Pressure (AP), Right Atrial Pressure (RAP), mean Pulmonary Artery Pressure (PAP), Pulmonary Wedge Pressure (PWP), Stroke volume (SV), Cardiac Index (CI), Stroke Work Index (SWI), Systemic Vascular Resistances (SVR), Pulmonary Total Resistances (PTR) were controlled every 30 minutes until the disappearance of the hemodynamic effects. ISDN did not produce any statistically significant changes; on the contrary NTG ointment caused significant changes in: (formula: see text). Decrease of RAP, PAP, PWP, PTR and increase of SV, CI, SWI were statistically significant from 30 until 180 minutes after NTG ointment administration. These changes were statistically different from those produced by ISDN (p less than 0,05). Thus NTG ointment, at this dose, improved cardiac performance, while oral ISDN 10 mg did not. It is concluded that the hemodynamic effects of NTG ointment are prompt and sustained.
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PMID:[Comparison between the hemodynamic effects of nitroglycerine ointment and oral isosorbide dinitrate in the treatment of left ventricular failure (author's transl)]. 680 18

Ten patients undergoing aortocoronary bupass surgery were studied during induction of anesthesia and during initial surgical stimulation. Each patient was anesthetized with fentanyl, 100 micrograms/kg, droperidol, 0.15 mg/kg, and pancuronium, 0.1 mg/kg, and ventilated with 100% oxygen. Preoperative medication consisted of propranolol, nitrate preparations, diazepam, 0.15 mg/kg orally, morphine, 0.15 mg/kg IM, and scopolamine, 0.4 mg IM. Intravenous, arterial, and Swan-Ganz catheters were inserted under local anesthesia after which control measurements of hemodynamic parameters and arterial blood gas tensions were taken. Observations were repeated after fentanyl, 50 micrograms/kg, after endotracheal intubation, after another dose of fentanyl, 50 micrograms/kg, after skin incision, and after sternotomy. The total dose of droperidol was given incrementally throughtout the fentanyl infusion. Normal saline was infused to maintain constant pulmonary capillary wedge pressure. Heart rate, left ventricular stroke work index, triple index, pulmonary capillary wedge pressure, and PaCO2 remained constant throughout the study. Systolic blood pressure decreased significantly after fentanyl, 50 micrograms/kg, and initial administration of droperidol, but thereafter remained unchanged. Stroke index increased significantly after fentanyl, 50 micrograms/kg, and remained elevated at all subsequent intervals. Cardiac index increased after fentanyl, 50 micrograms/kg and 100 micrograms/kg. Rate-pressure product was stable until the time of sternotomy after which it decreased significantly. In patients undergoing aortocoronary bypass surgery, 100% oxygen, fentanyl, 100 micrograms/kg, and droperidol, 0.15 mg/kg, produced stable hemodynamics during induction, intubation, and sternotomy. Maintenance of pulmonary capillary wedge pressure by volume infusion may have been contributed to this stability.
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PMID:Oxygen-high dose fentanyl-droperidol anesthesia for aortocoronary bypass surgery. 697 81

The purpose of this single-blind study carried out on 20 patients was to assess the effects of a long-acting nitrate derivative on the stroke index, which reflects left ventricular function. Following a 4 weeks' period of observation without any treatment (except for sublingual nitroglycerin during anginal attacks), an echocardiographic study of the left ventricle was performed. The distance between the endocardium lining the interventricular septum and that lining the posterior wall of the left ventricle was measured at the end of the diastole (R wave of the ECG) and at the end of the systole (shortest measurable distance). The rule of cubes was used to determine the ventricular volume and to calculate the stroke index. The patients then received pentaerythritol tetranitrate in daily doses of 240 mg for 30 consecutive days, after which a new echocardiographic study was done and the stroke index calculated again. The improvement in stroke index was more than three times the standard deviation before treatment in 15 patients (75%) and even six times greater in 8 of these (40%). No improvement was observed in the remaining 5 patients. In the group as a whole the stroke index increased from 0.418 +/- 0.135 to 0.504 +/- 0.115.
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PMID:Determination of ejection fraction by echocardiography in patients treated with P.E.T.N. 742 35


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