Amiodarone-associated "torsade de pointes". Relevance of concomitant cardiovascular medication in a patient with atrial fibrillation and structural heart disease.

A 69 year old female with history of coronary heart disease, myocardial infarction and paroxysmal atrial fibrillation suffered from occipital apoplexy. Under treatment with amiodarone 600 mg daily and concomitant medication with beta-acetyldigoxine (0.1 mg daily) and bisoprolole (1.25 mg daily), significant QT-prolongation (max. 700 ms; QTc: 614 ms) could be documented. Out of normofrequent sinus rhythm but as well out of bradycardia, the patient developed repetitive short-lasting "torsade de pointes" tachycardias (320 bpm) which terminated spontaneously. Serum electrolytes, plasma levels of digoxine (1.76 ng/ml) and amiodarone (1.9 mcg/ml) were within therapeutic range. This case report is the first to describe induction of amiodarone-associated "torsade de pointes" tachycardia during concomitant beta-blocker and digitalis medication in a patient with atrial fibrillation and structural heart disease. This points towards an elevated risk for proarrhythmia under this triple therapy.

Protection from digoxin-induced coronary vasoconstriction in patients with coronary artery disease by calcium antagonists.

Intravenous digoxin induces constriction of normal and stenotic coronary arteries in patients with coronary artery disease, which may lead to ischemic complications. We found that pretreatment with oral nisoldipine and intracoronary nitroglycerin neutralizes this digoxin-induced effect.

[Absolute bioavailability of beta-acetyldigoxin from tablets and drops in healthy subjects]. / Absolute Bioverfügbarkeit von beta-Acetyldigoxin aus Tabletten und Tropfen bei gesunden Probanden.

In a crossover design in random order 12 healthy male volunteers were given either beta-acetyldigoxin (Novodigal, CAS 5511-98-8) tablets, oral solution or i.v. application at a digoxin equivalent dose of 0.284 mg. To reach steady state each preparation was given for 10 days on a once-daily schedule. On days 8, 9 and 10 of each observation period blood was sampled to determine trough concentrations of digoxin in steady state. In addition, on day 10 blood was collected repeatedly at appropriate time intervals and urine was sampled concomitantly for 24 h. Trough values during steady state and 24 h AUC were used to calculate digoxin bioavailability for tablets and oral solution. From trough values, the mean bioavailability for beta-acetyldigoxin tablets was 91.2% (range 73.1-118.1) and for solution 93.8% (range 65.7-114.8). Using the AUCs 0-24 h at steady state bioavailability was calculated 77.7% for the tablets and 84.5% for the solution. Since trough values in steady state represent the body burden of digoxin which is supposed responsible for the therapeutic effect, trough values should be given priority for the determination of digoxin bioavailability from beta-acetyldigoxin tablets and solution. All formulations were well tolerated. No clinically relevant side effects were observed.

Differences in color discrimination between three cardioactive glycosides.

Color discrimination ability of 100 in-patients suffering from congestive heart failure and treated with digitoxin (D), pengitoxin (P), or digoxin (Dg) was determined with the Farnsworth-Munsell 100 Hue test (FM 100) and compared with the color discrimination of 72 in-patients who were not treated with digitalis glycosides (control group C). Parallel to the performance of the FM 100, the glycoside plasma level was measured by radioimmunoassay. The total error score (TES) of the FM 100 was correlated with the glycoside plasma level and the patient's age. In the C as well as in the D or P groups up to 172 errors and in the Dg group up to 586 errors were observed. With the exception of Dg, no differences were observed between the regression lines indicating an age-dependent increase in TES even under D or P treatment. In contrast to the two glycosides, Dg enhances the TES in therapeutically relevant plasma concentrations. The differences between the glycosides are due to differences in their volume of distribution and their plasma protein binding.

[The effect of cardiac glycosides on the visual system of man measured with cortical evoked potentials]. / Die Wirkung von Herzglykosiden auf das visuelle System des Menschen, gemessen mit kortikal evozierten Potentialen.

The effect of beta-acetyldigoxin (Novodigal) on color vision in normal, healthy subjects was studied using cortical evoked potentials. Initial results indicate a significant latency increase of one component of the visual evoked potential (VEP) and a dose dependency following a change of color from blue to red. The Farnsworth-Munsell-100-Hue test, however, showed no significant changes in color vision. It is postulated that the VEP is an even more sensitive measurement of color vision than subjective tests are.

Differences in color vision impairment caused by digoxin, digitoxin, or pengitoxin.

Color discrimination ability of 53 patients with congestive heart failure and 32 healthy volunteers treated with digoxin, digitoxin, or pengitoxin was determined with the Farnworth's Munsell 100 hue test. The patients had been treated with digitalis glycosides for several months prior to color vision testing. The volunteers received glycosides until a steady-state plasma concentration was reached. Glycoside plasma levels were measured by radioimmunoassay on the 3 days prior to color vision testing. The total error scores, indices of color discrimination, increased with the glycoside plasma levels. Subjects treated with digitoxin or pengitoxin exhibited no marked elevation in total error score at therapeutic concentrations, whereas 17 of 28 subjects with therapeutic digoxin plasma concentrations (less than 2.0 ng/ml) showed disturbed color discrimination. At toxic plasma levels all 5 digoxin-treated subjects, 7 of 13 digitoxin-treated subjects, and 3 of 8 pengitoxin-treated subjects showed impairment of color discrimination. The greater tendency of digoxin to impair color vision in comparison with digitoxin and pengitoxin may be related to a higher uptake or different distribution in the retina.

[Disorders of the ability to distinguish colors during digitalis therapy (author's transl)]. / Störungen des Farbunterscheidungs- vermögens unter Digitalistherapie.

31 hospitalized patients treated with beta-methyl digoxin and 34 treated with beta-acetyl digoxin were examined for color vision disturbances and compared with a control group (n = 17). The serum digoxin concentration was determined radioimmunologically. A significant correlation (p less than 0,01) was found between the severeness of the disturbances in color vision and the concentration of digoxin in the serum. The disturbances concerned different wave length regions. The lapse of time for disturbances in the distinguishing colors is being described in a case of suicidal intoxication.