[Doppler echocardiography determination of the minute heart volume in ergometric stress]. / Doppler-echokardiographische Bestimmung des Herzminutenvolumens während ergometrischer Belastung.

To prove the use of Doppler-echocardiography in the determination of cardiac output during supine bicycle exercise, 14 patients suffering from dilatative cardiomyopathy were studied. Cardiac output was simultaneously determined by Doppler-echocardiography and with radionuclide ventriculography. In some cases, cardiac output was additionally measured using the thermodilution technique. In 12 patients (success rate 86%) flow velocity signals from the ascending aorta could be recorded with sufficient quality. Both methods were closely correlated, the r-value was 0.91 and the standard error of estimate was found to be 2.09 l/min. Mean deviation was 1.50 l/min (0.09-5.45 l/min) or 13% (1%-64%) respectively. For changes in cardiac output with exercise, the correlation was r = 0.88 with a mean deviation of 69% (2%-453%). The coefficient of variation for exercise measurements was 19% and did not differ from the resting value of 20%. Comparing the mean values of the whole group, no differences between the two methods could be found at rest, during exercise or for changes from rest to maximal exercise. Using the suprasternal approach, aortic flow velocities can be assessed by Doppler-echocardiography during exercise. Gross estimation of cardiac output during exercise seems possible; judgement of changes in cardiac output in individual cases appears to be uncertain.

[Noninvasive determination of stroke volume with spectral Doppler echocardiography]. / Nichtinvasive Bestimmung des Herzzeitvolumens mit spektraler Doppler-Echokardiographie.

To assess the determination of volume flow by Doppler echokardiography 15 patients were studied twice in intervals of 2 to 6 hours. Cardiac output was determined simultaneously by thermodilution and by Doppler echocardiography. In three patients (20%) no Doppler signal could be recorded. In the 24 successful determinations a correlation of r = 0.93 was found between the two techniques. Mean deviation was 0.57 l/min (0.15-1.16), 9% (1-20%) respectively. With serial measurements the correlation for changes in cardiac output was 0.94. Mean deviation was found to be 0.47 l/min (0.12-1.16), or 75% (9-395%). Thus, gross estimation of cardiac output by Doppler echocardiography seems possible. However, it cannot be judged as of yet whether a more than semiquantitative estimation of individual cardiac output changes is possible nor whether further information can be obtained besides that which is clinically available.

[Pharmacokinetics and Antiarrhythmic effects of Prajmalium Bitartrate]. / Pharmakokinetik und antiarrhythmische Wirkung von Prajmaliumbitartrat.

8 patients with ventricular premature contractions were treated with prajmalium bitartrate (Neo-Gilurytmal) 20 mg q.i.d. The electrocardiograms were continuously monitored by a computerized arrhythmia monitoring system. For definition of the drug's pharmacokinetic properties plasma concentrations were determined. 7 patients showed a marked arrhythmia reduction. Mean ventricular premature contraction frequency was significantly reduced 6 h after onset of treatment, maximum arrhythmia suppression to 34% of control was observed after 24 h of treatment. The correlation of antiarrhythmic response and plasma concentrations was good. Mean plasma concentrations during steady state conditions were 218 ng/ml. Plasma half-life was determined 7.3 h. The lower limit of therapeutic plasma concentrations was between 43 and 145 ng/ml. A mean total clearance of 344 ml/min indicates a low hepatic extraction of prajmalium bitartrate. Moreover, the distribution volume of 204 l suggests a high tissue affinity of the drug.

Development of tolerance during nitrate therapy: dissociation of arterial and venous effects. A doppler echocardiographic study.

Using pulsed Doppler echocardiography as a noninvasive method to assess central venous return, nine healthy volunteers were studied before and after isosorbide dinitrate given four times daily for 8 days. First dose isosorbide dinitrate led to a drop in heart rate and mean arterial pressure, and right ventricular inflow velocities decreased. With sustained treatment effects on systemic venous return remained unaltered, whereas reduction in heart rate and in mean arterial pressure was lost. Regarding this disappearing response as indicating a form of tolerance, venous hemodynamic nitrate effects were unaltered by development of tolerance on the arterial side.