A woman with increasing weakness of the legs and irregular heartbeat who took her husband's medication.

A 78-year-old woman presented to the emergency room complaining of a 2-week history of general fatigue and increasing weakness in both legs. She also experienced an irregular heartbeat and had slight dyspnea. She had had a cardiac syncope 1 year earlier and received a pacemaker (VVI mode). The woman reported a history of arterial hypertension and mild chronic heart failure. Because of previous intermittent tachyarrhythmia, she was treated with 2380 mg sotalol and subcutaneously self-injected 0.3 ml nadroparin per day, a low-molecular weight heparin. She also received 10 mg enalapril, 0.07 mg digitoxin, 230.2 mg moxonidin, and 50 mg spironolactone per day. In addition to the prescribed medication, for approximately 2 months she had taking three to four effervescent tablets, originally prescribed for her husband, because she liked the refreshing taste of this sparkling preparation and felt that this was healthy. However, neither the patient nor her husband could recall the name of these tablets, but the husband promised to obtain the package. Physical examination revealed dry mucous membranes without evidence of peripheral oedema. The heartbeat was irregular, a 2u6 systolic murmur was present over the right 2.ICR. Pulmonary auscultation was normal. Blood pressure was 170u90 mmHg. She had serious problems standing and there were signs of paralysis. Deep tendon reflexes were absent in both legs. The admission electrocardiogram shows an arrhythmia interspersed with single pacemaker actions (Figure 1). In fact, the pacemaker saved the patient’s life because an immediately ordered serum potassium was 9.4 mmolul. There was no evidence of pseudohyperkalaemia such as haemolysis, or blood count abnormalities, and venipuncture was without problems. Serum sodium was 138 mmolul, calcium 2.60 mmolul, and chloride 111 mmolul. Creatinine was 1.3 mgudl, BUN 39 mgudl, and glucose 110 mgudl. Venous blood gas analysis showed a pH 7.35, PCO2 39.2 mmHg, and bicarbonate 21.1 mmolul. Digitoxin was within the therapeutic concentration (14 mgul).