Zeitschrift für Kardiologie
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The effect of Etilefrin on the blood flow of normal and partial ischaemic myocardium with heat conductance probes as well as on the ventricular dynamics was investigated on 11 dogs under propiomazine-pentobarbital narcosis. Etilefrin was applied in doses of 0.04 mg/kg bw. and 0.2 mg/kg bw. At low doses, the blood flow was only elevated in normal myocardium, likewise the systolic aortic pressure, the diastolic aortic pressure decreased, the heart frequency was elevated, whereas the systolic pressure in the left ventricle was only slightly increased for a short time, the enddiastolic pressure unchanged, dp/dtmax rose significantly, but the heart minute volume only slightly. ⋯ The heart frequency was more elevated than at lower doses, the pressures in the left ventricle showed no obvious changes, dp/dtmax and heart minute volume were likewise considerably elevated. Radiological measurements of the ejection fraction and the mean circumferential fiber shortening velocity at higher Etilefrin doses showed also a positive inotropic effect. In consideration of this fact, therapy with Etilefrin appears useful in disturbances of cardiac function and at least shows no contraindication by means of myocardial blood flow.
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Fifty-eight patients with atrial fibrillation treated with digoxin were studied to determine the correlation between serum digoxin levels and the ventricular rate. The study was a computer-based exercise, processing a signal consisting of R-R intervals, derived by point-digitising electrocardiograms. The means, variances and centers of gravity of power-spectra from the signal were correlated with serum digoxin levels, the peripheral pulse and with each other. ⋯ The negative correlation and this significant difference are best explained by the gradual increase in the dose administered to non-responders by the attending physicians who did not fear over-dosage because of frequent serum level determinations. It is concluded that the serum digoxin level is a poor predictor of the ventricular rate in patients with atrial fibrillation because of marked individual differences. These are due to the poor representation by serum levels of drug concentration at the point of interest (A-V node) and the non-linearity of the chronotropic effect of digitalis.
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Eight own cases of the so-called pacemaker twiddler's syndrome in pervenously implanted pacemaker-electrode-systems are reported. A scheme to classify that syndrome is proposed mentioning the grade of distinction and mechanism. Furthermore preconditions, therapy, and steps that will have been taken to prevent a pacemaker twiddler's syndrome are discussed.