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Biomedical subjects

B Ramdohr

Publications and source records attributed to B Ramdohr.

At least 19 recordsLinked to original sources
PubMed1976

Dopamine induced hypoxemia in patients with left heart failure.

Previous studies in our laboratory have demonstrated that dopamine produces a significant decrease in arterial PO2 and a mild increase in arterial PCO2 in patients with left heart failure. The present investigations were designed to find out dopamine-induced effects impairing gas exchange. In patients with left heart failure and pulmonary congestion the true pulmonary shunt has been determined by O2-breathing. A statistically significant increase of true shunting could be evaluated. However, from calculations of the components composing AaDO2-air it can be demonstrated that most of dopamine-dependent increase of AaDO2-air is due to an elevated diffusion-distribution gradient. This dopamine effect on arterial PO2 does not limit dopamine application because oxygen administration will outrange the side effect. As changes of ventilation did not occur dopamine is assumed to open up pulmonary vessels producing blood flow in poorly ventilated parts of the lungs and causing an increased disturbance of ventilation/perfusion ratio. The increased true pulmonary shunt can be regarded as result of perfusion of totally unventilated lung areas when dopamine is infused. Haloperidol can attenuate dopamine-dependent decrease in arterial PO2. How haloperidol abolishes this dopamine effect on arterial oxygen tension remains unknown.

Carbon Dioxide↗
PubMed1976

[Effect of tricyclic antidepressive agents on hemodynamics and plasms norepinephrine level in man during rest and exertion].

The effects of i.v. injected antidepressants Imipramine (Tofranil, Geigy) and Dimetacrine (Istonil, Siegfried) on cardiavascular functions were investigated in 18 patients at diagnostic cardiac catheterization. 4 patients were additionally studied during ergometric exercise before and 45 min. after application of both thymoleptica. Determinations of noradrenaline plasma concentrations were carried out in 8 patients. The results show of 25 mg (= 22,1 mg free base) Imipramine or 33.5 mg (= 21.4 mg free base) Dimetacrine did not induce significant changes in heart rate and cardiac index. 2. Already 15 min. after application of both drugs a clear increase in left ventricular end-diastolic pressure (LVEP) was observed. Maximal increase in LVEP - in mean, 26% after Imipramine (p less than 0.0005) and 40% after Dimetacrine (p less than 0.05) - was reached 30-45 min, after injection. 3. A simultaneous increase in mean systemic arterial pressure was related to a marked increase in noradrenaline plasma concentration in all 8 investigated patients. 4. After application of tricyclic antidepressant a larger increase in pulmonary arterial enddiastolic pressure was observed during ergometric exercise.

Acridines↗
PubMed1975

Cardiovascular side effects of tricyclic antidepressants - a risk in the use of these drugs.

Following the increasing use of tricyclic antidepressants, numerous side effects of these drugs are reported, e.g. ECG changes and cases of "sudden death". Because of the fact that haemodynamic studies in man and studies on the possible correlation between the structure of these drugs and their negative inotropic effect are lacking, we have investigated the influence on myocardial contractility of cat papillary muscle induced by impramine and dimetacrin as well as their desmethyl compounds (n = 42). Furthermore, the effects of i.v. administration of imipramine and dimetacrine on cardiovascular functions were investigated in 18 patients at cardiac catheterization. In addition, four patients were studied during ergometric exercise before and 45 min after injection of both drugs. Finally, fluorimetric determination of norepinephrine plasma concentrations were carried out in 8 patients.

Acridines↗
PubMed1975

Comparative in vitro and in vivo studies on the effects of tricyclic antidepressants on myocardial contractility.

The effects of the similarily structured antidepressant drugs imipramine and dimetacrine and their demethylated derivatives on myocardial performance were studied in vitro on 42 right ventricular papillary muscles of cats. The hemodynamic effects of intravenous administration of 22 mg of free base imipramine and dimetacrine were investigated in 12 patients with coronary disease. The results of the in vitro studies show that imipramine greater than dimetacrine greater than desmethyl compounds have a marked dose-dependent negative inotropic effect on all parameters of myocardial contractility, i.e., afterloaded isotonic contractions (delta L), dL/dtmax, dL/dtmin,dT/dt. The hemodynamic investigations indicate that imipramine greater than dimetacrine induces a significant increase in end-diastolic left ventricular pressure. Both drugs increase mean arterial blood pressure, correlated to a peripheral vasoconstriction and corresponding to an increase on the plasma level of catecholamines. It is concluded that both effects of these antidepressant drugs (reduction of myocardial performance and an increase in the plasma level of catecholamines) must be considered a risk in patients predisposed to myocardial failure.

Acridines↗