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

Two types of vasodilators are used for treatment of acute myocardial infarction: Nitrates on the one hand with predominant venodilation and agents like Phentolamie and Nitroprusside on the other hand with venodilation as well as arteriolar vasodilation. Different opinions exist with respect to indication of these vasodilators. They are used for reduction of arterial blood pressure, for reduction of left ventricular filling pressure and for increase of cardiac output. A marked decrease in ejection fraction is the hemodynamic basis of application of vasodilators in the latter indication. By reduction of peripheral vascular resistance emptying of the left ventricle in these patients is enhanced.) As a working hypothesis in clinical situation elevated filling pressure indicates a decreased ejection fraction. The first part of this investigation deals with relation of left ventricular and diastolic pressure to ejection fraction. A good correlation between these two parameters was found in 717 patients with coronary artery disease. However variability was so wide that regression from enddiastolic pressure to ejection fraction in the individual seemed impossible. In 26.6% of patients with ejection fraction over 0.6%, filling pressure was 20 mm Hg or more. On the other hand, in 34.7% of patients with ejection fraction below 0.3% filling pressure was 20 mm Hg or less. As a consequence of practical value, reduced ejection fraction has to be assumed, if a patient presents elevated filling pressure and reduced cardiac output. In the second part, the hemodynamic effects of Phentolamine in 12 patients with acute myocardial infarction and elevated filling pressure (PCV resp. PADP greater than 18 mm Hg) are described. Maximal effects on hemodynamic variables were: reduction of peripheral vascular resistance by 31.4%, of left ventricular filling pressure by 16.2%, and of mean arterial pressure by 17.0%. Cardiac output increased by 25.8% and heart rate rose by 14.8%. At optimal efficacy, stroke volume increased by 23.7%. Further increase of infusion rate with concomitant fall of peripheral vascular resistance resulted in decrease of stroke volume and tachycardia. Most serious side effects consisted in sudden fall of blood pressure. Therefore intraarterial monitoring of blood pressure is demanded. The third part deals with hemodynamic effects of nitrates (Isosorbiddinitrate 10 mg p.o.) in patients with acute myocardial infarction and elevated filling pressure. One hour after application peripheral vascular resistance decrease by 16.5%, filling pressure by 20.8%, and mean arterial pressure by 9.0%. Cardiac output stroke volume and heart rate did not change significantly. No side effects were observed with Isosorbiddinitrate although two cases of nitrate syncope occurred with Nitroglycerin, resulting in bradycardia and hypotension. Indications for vasodilator therapy therefore has to be handled as follows: Nitrates should be given to patients with elevated filling pressure and normal cardiac output...
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PMID:[Hemodynamic guidelines in the treatment of acute myocardial infarction by means of vasodilators]. 16 46

The method of radionuclide cardangiography (RNCA) has become a well-established method amongst non-invasive assessments in coronary heart disease (CHD). By means of RNCA the most important parameters of left ventricular function, viz. ejection fraction (EF) and wall motion (WM), can be determined very exactly. The first bolus pass method (FBP), which allows satisfactory separation between right and left heart, enables the additional determination of EF distribution, stroke volume (SV) and SV distribution. This method requires the technical necessity of a multicrystal gamma camera. Special nuclear medicine characteristics have been worked out for different groups of CHD. EF and WM show typical signs of angina pectoris, caused by exercise correlating with reduced perfusion in the referring section of WM. While these changes may be reversible after nitrate administration, pathological myocardial function caused by acute myocardial infarction (AMI) or manifest heart failure is not reversed by nitroglycerine. Typical findings were seen in the course of AMI: initial decrease in global EF and diffuse (multilocated) asynergies in the left ventricular wall; in the second week possible start of recovery, including regression of dyskinesia to akinesia at the end of hospitalization. Especially in the early phase of AMI it was demonstrated that FBP--as a non-invasive technique--gives high information quality which is unequalled by other comparable methods. Therefore, the described method of FBP should be classified as very useful and effective in clinical cardiology.
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PMID:[Radionuclide cardangiography as non-invasive assessment in coronary heart disease (author's transl)]. 39 49

Membrane-bound nitrate reductase of Escherichia coli consists of three subunits designated as A, B, and C, with subunit C being the apoprotein of cytochrome b, A hemA mutant that cannot synthesize delta-aminolevulinic acid (ALA) produces a normal, stable, membrane-bound enzyme when grown with ALA. When grown without ALA, this mutant makes a reduced amount of membrane-bound enzyme that is unstable and contains no C subunit. Under the same growth conditions, this mutant accumulates a large amount of a soluble form of the enzyme in the cytoplasm. Accumulation of this cytoplasmic form begins immediately upon induction of the enzyme with nitrate. The cytoplasmic form is very similar to the soluble form of the enzyme obtained by alkaline heat extraction. It is a high-molecular-weight complex with a Strokes radius of 8.0 nm and consists of intact A and B subunits. When ALA is added to a culture growing without ALA, the cytoplasmic form of the enzyme is incorporated into the membrane in a stable form, coincident with the formation of functional cytochrome b. Reconstitution experiments indicate that subunit C is present in cultures grown without ALA but is reduced in amount or unstable. These results indicate that membrane-bound nitrate reductase is synthesized via a soluble precursor containing subunits A and B, which then binds to the membrane upon interaction with the third subunit, cytochrome b.
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PMID:Biosynthesis of membrane-bound nitrate reductase in Escherichia coli: evidence for a soluble precursor. 77 Apr 17

Hemodynamic and electrocardiographic analysis during rapid right atrial stimulation was performed before and one, two, and four hours after oral application of longacting nitroglycerin (5 mg) and isosorbide dinitrate (20 mg) in 11 and 9 patients, respectively with coronary heart disease. Atrial stimulation without nitrate induced significant ischemic ST segment depression. Cardiac output showed a small decrease and the mean arterial, pulmonary artery, and pulmonary wedge pressure increased. Isosorbide dinitrate reduced the ischemic reaction by 40% from the first to the fourth hour after application. Cardiac output, stroke volume, aterial, pulmonary artery, and pulmonary wedge pressure also decreased continuously. Nitroglycerin caused a similar reduction of ischemic ST segment depression for two hours. Systolic, diastolic, and mean arterial pressure decreased significantly. Cardiac output, stroke volume, and pulmonary artery pressure remained unchanged. It was concluded that the applied dose of isosorbide dinitrate showed a more extensive longacting effect.
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PMID:[Hemodynamic and electrocardiographic prolonged nitrate effect during frequency load in coronary disease]. 82 Jan 4

Metabolic, temperature, and cardiorespiratory responses of 19 healthy males, age range 18-30 yr for one group and 40-55 yr for another, were studied during 210 minutes submaximal work at 35% Vo2 max. The subjects were exposed to four different pollutant gas mixtures at two different temperatures, 25 degrees C and 35 degrees C (relative humidity 30%). The four gas mixtures were filtered air (FA), 50 ppm carbon monoxide in filtered air (CO), 0.24 ppm peroxyacetyl nitrate in filtered air (PAN), and a combination of all three mixtures (PANCO). In the CO exposure, the heart rate was significantly greater than that observed during FA conditions (P less than 0.05). Metabolic and thermoregulatory responses to long-term work were not different in the various pollutant environments. Significant decreases in stroke volume and increases in heart rate were observed during the course of the 25 degrees C exposures with no alteration in cardiac output. Heart rates were higher during 35 degrees C exposures while cardiac output remained at the same level with a consequent further reduction in stroke output.
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PMID:Man's physiologic response to long-term work during thermal and pollutant stress. 119 54

1. Four cumulative 10 min intravenous infusions of 0.05, 0.2, 0.5 and 2.0 mg min-1 were used to compare the cardiovascular profile of 5 novel nitrate-esters dissolved in Intralipid 10% to that of nitroglycerin (GTN) in conscious pigs. 2. Infusion of Intralipid 10% alone had no effect on any of the systemic haemodynamic parameters. GTN infusions decreased mean arterial blood pressure dose-dependently from 94 +/- 2 mmHg to 79 +/- 3 mmHg (P less than 0.05) and raised cardiac output from 2.74 +/- 0.09 l min-1 to 3.40 +/- 0.18 l min-1 (P less than 0.05) due to an increase in heart rate (by up to 43 +/- 3%), as stroke volume decreased slightly. Systemic vascular resistance decreased (by 32 +/- 3%) and left ventricular end-diastolic pressure fell from 5.2 +/- 0.4 mmHg to 2.2 +/- 0.5 mmHg (both P less than 0.05). 3. The novel compounds CEDO 8811, CEDO 8834 and CEDO 8901 increased cardiac output only at the highest dose (7%, 8% and 9%, respectively). There was no change in mean arterial blood pressure as the increase in cardiac output was counterbalanced by arterial vasodilatation. All three compounds reduced left ventricular end-diastolic pressure slightly. 4. CEDO 8816 was a more potent arterial and venodilator than the aforementioned CEDO compounds, as the decreases in systemic vascular resistance and left ventricular end-diastolic pressure were already significant at lower doses. The fall in stroke volume was fully compensated by the increase in heart rate and as a result cardiac output increased by 11 +/- 3% (P less than 0.05) at the highest dose. 5. CEDO 8956 was the most potent vasodilator of the novel compounds and exhibited a cardiovascular profile similar to that of GTN. Left ventricular end-diastolic pressure decreased significantly during infusion of 0.2mgmin-'. Mean arterial blood pressure decreased by 11 +/- 2% (P < 0.05) in spite of an increase in cardiac output by up to 20 +/- 2% (P < 0.05), due to a decrease (by 27 +/- 1%, P <0.05) in systemic vascular resistance. The increases in heart rate (20 +/- 5%, P < 0.05) and LVdP/dtmax (38 +/- 4%, P < 0.05) were, however, considerably less after CEDO 8956 than after GTN. 6. The potential of CEDO 8956 in the treatment of chronic left ventricular dysfunction was evaluated during administration to conscious pigs (21-23 kg), in which the left circumflex coronary artery was ligated 4 weeks earlier. In these animals, baseline values for cardiac output and LVdP/dtx were lower and those of systemic vascular resistance and left ventricular end-diastolic pressure were higher than in the first group of experiments. 7. Both GTN and CEDO 8956 in doses of 0.05 to 2.0 mg inm increased cardiac output dosedependently (by up to 34% and 19%, respectively). The decrease in systemic vascular resistance was larger with GTN (35%) than with CEDO 8956 (17%), which resulted in a 13% decrease in mean arterial pressure during infusion of GTN, whereas there was no change in mean arterial pressure during infusion of CEDO 8956. Both compounds increased LVdP/dt,,,,X (by 48% and 30%, respectively) and lowered left ventricular end-diastolic pressure to normal levels. 8. At a dose of 1.0Omg min- 1, both GTN and CEDO 8956 increased left ventricular blood flow parallel to the increase in myocardial oxygen demand. At this dose, GTN also caused vasodilatation in the vascular beds of the brain, kidneys and adrenals. With CEDO 8956 no significant changes were achieved. 9. We conclude that the cardiovascular profile of CEDO 8956 in both normal animals and in animals with chronic left ventricular dysfunction warrants further study on its usefulness in the treatment of a number of cardiovascular disorders.
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PMID:Cardiovascular profile of 5 novel nitrate-esters: a comparative study with nitroglycerin in pigs with and without left ventricular dysfunction. 178 21

The geometry of both the infarcted and non-infarcted zone of the left ventricle changes after myocardial infarction. Two mechanisms are involved: expansion of the infarcted zone and secondary dilatation of the non-infarcted zone. The necrosed area undergoes an inflammatory reaction followed by fibrosis which end up as a sca within a period of a few days to a few weeks. During this period if fibrous scarring the infarcted, thinned myocardium undergoes progressive expansion which starts in the first hours of the myocardial infarction. The loss of left ventricular systolic function related to the infarct and volumic overload created by expansion of the infarct influence the secondary development of dilatation of the non-infarcted zones. This dilatation results in restoration of left ventricular stroke volume but at the price of increased wall stress, which itself induces compensatory wall hypertrophy. These phenomena are more pronounced when the initial infarction is extensive and if they are sustained, they result in definitive myocardial failure. Several factors influence remodeling: the size of the infarct, arterial patency, wall stress and the quality of the scarring process itself. Therapeutic interventions of each of these factors can influence the remodeling. Limitation of infarct size by thrombolytic therapy, arterial revascularisation, even when performed late, seem capable of limiting expansion of the necrosed zone. Pharmacodynamic intervention of left ventricular afterload also affects ventricular remodeling. Nitrate derivatives, vasodilator therapy in general and converting enzyme inhibitors have been shown to be effective.
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PMID:[Physiopathology of left ventricular remodeling after myocardial infarction]. 183 20

Twenty-four patients were randomized to a double-blind, triple placebo controlled, latin square protocol to examine the relative efficacy of propranolol or diltiazem given as monotherapy or in combination with isosorbide dinitrate. Treatment phases were preceded and followed by placebo control periods. At the end of each phase, symptom-limited treadmill exercise stress tests were performed, as well as rest and exercise radionuclide ventriculography. Both forms of monotherapy were effective in reducing episodes of angina and nitroglycerin use, and in improving exercise tolerance. Diltiazem monotherapy was associated with slightly higher treadmill times (509.9 +/- 123 s) compared to propranolol (462.7 +/- 131 s, P less than 0.05). The addition of isosorbide dinitrate to either form of monotherapy allowed no further improvement in any of the measured clinical responses. Radionuclide ventriculography showed no significant difference in resting left ventricular function. The addition of isosorbide dinitrate to propranolol showed a reduction in end diastolic volume in keeping with a reduction in preload. In response to exercise, stress-induced left ventricular dysfunction was equal in all groups except for the diltiazem-nitrate combination, which was associated with a higher ejection fraction (56.2 +/- 8.6%) compared to monotherapy (52.6 +/- 10.9%, P less than 0.01). A higher cardiac output could be achieved in the groups treated with diltiazem; this was related to increased heart rate and maintenance of stroke volume. It was concluded that diltiazem is equally effective as propranolol for the treatment of chronic stable angina and, in terms of exercise capacity and cardiac output, superior to beta-blockade. The addition of isosorbide dinitrate appears to impart no overt benefits, but some evidence suggests a reduction in left ventricular decompensation in the face of stress.
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PMID:Clinical response and effects on left ventricular function of isosorbide dinitrate added to propranolol or diltiazem monotherapy in patients with chronic stable angina. 204 86

To determine whether a 72-hour infusion of nitroglycerin produces hemodynamic improvement in patients with severe congestive heart failure and to assess the contributing role of various possible causes of hemodynamic tolerance to nitroglycerin, 19 patients received an infusion of nitroglycerin 1.5 micrograms/kg/min for 72 hours. In a subgroup of patients (n = 10), there was an increase in stroke work index and a decrease in ventricular filling pressures throughout the infusion and even after it was discontinued. Tolerance to the hemodynamic effects of nitroglycerin was partially reversed 8 hours after the infusion was stopped. Neurohumoral changes occurred but appeared to play only a minor role in the development of nitroglycerin tolerance. However, hematocrit fell 9 +/- 5%, which suggests that an increased intravascular volume contributed to tolerance. In summary: (1) a 72-hour infusion of nitroglycerin improves ventricular function in some patients with severe heart failure; (2) volume shifts from the extravascular to the intravascular compartments may, at least in part, be responsible for nitroglycerin tolerance; and (3) reflex neurohumoral activation may also play a small role in nitrate tolerance.
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PMID:Sustained beneficial effect of a seventy-two hour intravenous infusion of nitroglycerin in patients with severe chronic congestive heart failure. 211 45

The haemodynamic influence of positive inotropic therapy with dobutamine, both alone and when combined with isosorbide dinitrate, was evaluated in 10 consecutive patients admitted to Coronary Care with acute left ventricular failure (pulmonary artery occluded pressure greater than 20 mm Hg) complicating myocardial infarction. Dobutamine increased systemic arterial blood pressure and heart rate without reduction in the left heart filling pressure; cardiac index (+0.9 L/min/m2; p less than 0.01) was substantially increased. Thus, consequent on these effects, dobutamine could increase myocardial oxygen requirements. The addition of intravenous isosorbide dinitrate reduced systemic arterial pressure and left heart filling pressure; the augmented cardiac index following therapy with dobutamine alone was maintained. Combined dobutamine/nitrate therapy, therefore, appeared haemodynamically superior to dobutamine monotherapy, in that it improved cardiac stroke volume at a normalised left ventricular filling pressure. These data suggest that combined dobutamine/nitrate therapy may prove useful as an adjunct to the treatment of normotensive heart failure complicating acute myocardial infarction.
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PMID:Haemodynamic advantages of a combined inotropic/venodilator regimen over inotropic monotherapy in acute heart failure. 241 5


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