[Post-infarction ventricular function in relation to the contractility of the remaining myocardium (author's transl)].
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Biomedical subjects
Publications and source records attributed to W Delius.
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The effect of acute beta-adrenoceptor blockage (Metoprolol) (M), 0.1 mg/kg i.v.) on left ventricular performance has been investigated at rest and during exercise in 15 patients with 2--3 months old transmural myocardial infarctions. Coronary venous and arterial norepinephrine (NE) concentrations were determined. There was no significant change in arterial and coronary venous NE concentrations (0.27 and 0.22 ng/ml, respectively) after blockage of beta-adrenoceptors (0.36 vs 0.26 ng/ml), which caused a fall of stroke volume from 79 to 68 ml, a reduction of ejection fraction from 62 to 55% and of circumferential fibre shortening form 1.2 to 0.9 circ/sec. During physical exercise the plasma NE concentration in the arterial (0.51 ng/ml) and coronary venous (0.6 ng/ml) blood increased significantly and increased even further to 0.65 and 0.76 ng/ml, respectively, following administration of Metoprolol. The arterio-coronary sinus difference in NE concentrations demonstrate a release of NE from the myocardium. As compared to control values, heart rate following Metoprolol was lower (116 vs 106/min), mean PCV pressure was slightly increased (from 21 to 23 mm Hg) and there was a fall of cardiac index from 6.3 to 5.2 l/min X m2. It is likely that the increased sympathetic activity after Metoprolol and during exercise is a compensatory reaction due to the hemodynamic effects of blockade of beta-adrenoceptors. Further studies are in preparation in order to find out if this is only a transient phenomenon during the early adaptation phase after blockade of beta-adrenoceptors.
Ten patients in severe cardiac failure were treated with dopamine (4 microgram/kg . min) and dobutamine (7.5 microgram/kg.min). Both drugs brought about a similar increase in stroke volume and cardiac output of about 50% and 60%, respectively, accompanied by a fall in peripheral vascular resistance of about 33%. On dopamine the heart rate increased by 12%, but remained unaltered on dobutamine. There was a significant fall in the preload of both ventricles with dobutamine, while ventricular filling pressure during dopamine infusion was only slightly decreased, unchanged or even increased. The pulmonary (wedge) pressure during dopamine infusion averaged 9 mm Hg higher than during dobutamine (P less than 0.001). There is thus the potential danger with dopamine of aggravating pulmonary congestion. Furthermore, the improvement in cardiac function due to dopamine is at the expense of a higher oxygen demand than with dobutamine. Dobutamine is, therfore, preferable to dopamine in the treatment of advanced myocardial failure.
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Metoprolol, a cardioselective beta-receptor blocker, was administered to 12 patients three to ten hours after sustaining a transmural myocardial infarction, and the effect of the drug (10 mg i.v., followed by 50 mg orally every eight hours) was followed for 48 hours. Heart rate decreased by 16% and cardiac output by 27%, while blood pressure and stroke volume decreased little and pulmonary "wedge" pressure was not significantly changed. Even in patients with initially definitely elevated left-ventricular filling pressure (greater than 20 mm Hg) the drug was well tolerated without any further rise in pressure. Since left-ventricular work was significantly decreased (stroke work--15%, cardiac output--31%) and the duration of diastole, decisive for coronary perfusion, was prolonged, it is concluded that early administration of beta-receptor blockers has a favourable effect on myocardial oxygenation and possibly reduce ultimate infarct size.
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In patients with valvular heart disease the initial systolic ejection rate was determined in an attempt to characterize ventricular function in pressure and volume overload. By means of left ventricular cineangiography, the volume change during the initial third of the ejection phase was determined and the mean ejection rate of this period was calculated. A total of 40 patients were examined, 7 patients without heart disease, 15 patients with pure aortic regurgitation, 9 patient with pure aortic stenosis and 9 patients with pure mitral regurgitation. In patients with pure aortic regurgitation and high-normal values for ejection fraction and mean velocity of circumferential fiber shortening (mVcf) a significant increase in initial systolic ejection rate when compared to the group of normals was observed. The distribution of the stroke volume for each third of the ejection phase corresponded to the normal pattern. In contrast, in patients with low-normal values for ejection fraction and mVcf, a decrease in the initial systolic ejection rate below the normal value was observed, along with a pathological distribution of the stroke volume during the ejection phase. This finding was also noted in all patients with pure mitral regurgitation and pure aortic stenosis. In aortic stenosis, the decline in initial systolic ejection rate was regarded as a consequence of the outflow tract obstruction, whereas in volume overload, this was regarded as a sign of a decline in ventricular function which is not recognized with global parameters such as ejection fraction and mVcf.
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Because of their rapidly changing hemodynamic inconstancy depending on many, sometimes competing, processes, hypertrophic cardiomyopathies present a clinical picture extraordinary among the cardiac diseases, with severely altered diastolic compliance of the left ventricle and a functional stenosis in the obstructive forms. They are of increasing importance for the doctor in hospital or general practive, particularly because they are among the very few diseases in which the usual cardiac therapy with digitalis or else the administration of sympathomimetics is contraindicated.
210 patients were followed up by the actuary method for over 5 years after isolated mitral valve replacement or a double valve replacement. After isolated valve replacement the one month survival including the operative mortality was 92+/-2%. The survival after one year was 83+/-3% and after 5 years 66+/-7%. The five year survival of patients in preoperative class III (according to the NYHA) was 73+/-8% and of class IV 57+/-8% (P less than or equal to 0.1). A comparison of valve replacements for pure mitral stenosis or mitral insufficiency showed no statistically significant differences. In the 37 patients who had a double valve replacement the survival risk was not increased in comparison with those patients who had had a single valve replacement. Age above 45 years and a preoperative markedly raised pulmonary arteriolar resistance reduced the chances of survival.
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Knowledge and due consideration of the natural history of valvular heart disease are prerequisites for their operative therapy. Presumptive mortality and morbidity of the surgical intervention must be weighted against the expected prognosis under medical treatment alone. The timing of the operation depends on these considerations. Mitral stenosis and the chronic forms of mitral and aortic incompetence have similar natural histories and for both signs and symptoms are good indicators for an eventual progression of the condition. The length of the period during which the patient is free of complaints may be quite variable but a critical change in the natural history comes about once the disease causes signs and symptoms. Surgical repair is indicated when the patient reaches stage III according to the NYHA-classification. The prognosis is worst for aortic stenosis, in particular due to the danger of sudden death. Patients with high pressure gradients are at particularly high risk; this holds even true for those patients which are not yet suffering from any complaints. The prognosis becomes even more serious, when signs such as dyspnea, anginal pain, or syncopal attacks occur. Prognosis and indication for surgical intervention cannot be evaluated reliably by considering only the clinical signs without knowledge of hemodynamic parameters. Acute mitral and aortic incompetence, in paricular when they occur during baterial endocarditis, must be observed very closely because of their most serious prognosis; if necessary, emergency surgery must be carried out in these cases.
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Dobutamine, a new catecholamine with a positive inotropic action, was given by infusion to 9 patients with cardiac failure in a dosage of 5 and 7.5 mug/kg-min over a period of 15 minutes. An improvement of left ventricular function was proven by an increase of cardiac output by 33%, a reduction of end-diastolic pressure from 21 to 14 mm Hg, an improvement of left ventricular ejection fraction from 29 to 39% and of the mean circumferential fibre contraction velocity from 0.4 to 0.8 circ/s. The systolic aortic pressure increased by a mean of 14% (5 mug/kg-min) and 23% (7.5 mug/kg-min). However, the resistance of the systemic circulation decreased from 1858 to 1439 and 1444 dyn-s-cm-5. Cardiac frequency remained unchanged with a dosage of 5 mug/kg-min and increased by a mere 7 beats/min with a dosage of 7.5 mug/kg-min. There was no increased tendency for arrhythmia. Dobutamine thus appears to act relatively selectively on myocardial beta-1 receptors. Results so far indicate therapeutic success in patients with severe cardiac failure, particularly in the low-output syndrome.
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Clinical, haemodynamic and angiographic findings in 50 patients with congestive cardiomyopathy were related to subsequent clinical course (mean observation period of 40 months). Ejection fraction and changes in mean pulmonary "wedge" pressure on ergometric exercise proved to be the most reliable criteria for judging left-ventricular function. During the period of observation 11 patients had died, in 15 the clinical state had deteriorated by one or two functional classes, and in 24 there had been no change. Patients with progressing disease differed from those clinically unchanged by having a smaller cardiac index, increased end-diastolic left ventricular pressure, higher pulmonary arterial pressure and smaller ejection fraction. Prognosis was no worse with atrial fibrillation than with sinus rhythm. Four of 13 patients with left bundle branch block died during the observation period and in seven the clinical state had deteriorated by one or two functional classes. The tested variables apparently have a good prognostic value.
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