[An unusual case of "catecholamine necrosis" caused by accidental digitalis poisoning]

Toxic manifestations of digitalis are one of the most prevalent adverse drug reactions encountered in clinical practice. The estimated incidence is about 20% in hospitalized patients in the USA. The authors describe a rare case of myocardial "catecholamine necrosis" (anteroseptal myocardial infarction) during accidental digitalis intoxication. A male patient, 75 years old, suffering from cirrhosis and ascites, take on by mistake a tablet of digoxin 0.25 mg. four times at day for eleven days. He hadn't heart disease in the past. At the eleventh day the patient showed a deep tiredness and so he was submitted to a clinical examination and electrocardiogram. The ECG demonstrated an anteroseptal myocardial infarction in the second-third electrical stage. The patient was hospitalized. The successive examination revealed: very high plasma digitalis concentrations; an increase of the serum levels of CPK and LDH; a significant increase of plasmatic and urinary catecholamine levels which return to normal values after fifteen days; apical akinesia at the echocardiographic examination; no signs of residual myocardial ischemia to the echo-dypiridamole stress test; normal coronary artery to the coronary arteriography and absence of coronary artery spasm to the ergonovine test. Furthermore the abdominal echography and the abdominal computerized tomography didn't reveal surrenal disease but showed an important liver disease. The patient was free from other cardiac events in the follow-up. Generally, during the digitalis intoxication we observe various rhythm and conduction disturbances. Instead in this case no serious arrhythmias were registered and the main expression of the drug toxicity was an anteroseptal myocardial infarction with undamaged coronary artery. Also the usual extracardiac symptoms and signs of the digitalis intoxication were absent in this case. All these observations can be explained with the pathological increase of the cathecholamine levels, indirectly induced by digitalis; with the direct toxic effect of the drug at the myocardic level; with the contemporary absence of ionic disturbances; with the concomitant liver disease. The direct toxic effect of the digitalis produced an increase in calcium ions availability for the electromechanical coupling and an increase of the intramyocardial pressure; the increase of the adrenergic activity determined contemporary an increase in the oxygen consumption of the myocardial cells, a rise of vascular tone and coronary artery tone and a reduction of the duration of the diastole. All these factors provoked a "primary and secondary" ischemia which evolved toward a real "cathecholamine necrosis" and produced a myocardial infarction. This hypothesis explains the myocardial infarction in absence of injury at the coronary arteriography and without coronary spasm at the ergonovine test; moreover it explains the transient increase in cathecholamine plasma levels observed in the acute phases an normalized after fifteen days. The "cathecholamine necrosis" is an anatomical definition, nevertheless in our opinion it gives account of the rare clinical situation observed.