1098 showed a slightly enlarged heart with opacities at the right lung base suggestive of post-radiation fibrosis (she had had radiotherapy post-mastectomy 3 years previously). Blood tests normal. The carbamazepine dose was increased to 5 x 200 mg/day, with considerable reduction in pain. However, her pulse-rate fell to 44/min 3 days after starting the increased dose. She felt lightheaded on sitting up. The E.c.G. showed sinus bradycardia. When the dosage was reduced to 600 mg/day, the patient’s pulse rose to normal (74/min) within 48 h. The patient’s pain has been controlled on a dose of 200 mg three times daily during a 3 month follow-up period. There seems little doubt that this patient’s bradycardia was related to the increase in her carbamazepine. Unlike the Swedish patient,2 she had no history of heart-failure but postradiation fibrosis may have affected her conducting tissue, becoming a problem only when the carbamazepine dose rose. Metastasis from her breast carcinoma to her conducting tissue cannot be ruled out. Steiner et al. found that the drug prolonged atrioventricular conduction moderately, in vivo, in dogs but did not effect intra-atrial or intraventricular- conduction. Carbamazepine restored sinus rhythm in dogs with ventricular arrhythmias induced by digitalis. The most common side-effects of carbamazepine are ataxia, drowsiness, and allergic reactions.4 Beerman et al. suggested that the lack of reports of cardiac effects after oral carbamazepine indicates that a prerequisite for induction of atrioventricular block might be an already defective conduction system. They recommended that the drug should be prescribed with caution to such patients. This warning deserves emphasis especially since trigeminal neuralgia often occurs at an age when cardiovascular disturbances first become apparent. Perhaps some of the side-effects associated with this drug are due to unsuspected episodes of bradycardia rather than direct cerebral or cerebellar action. were

Department of Medicine, Repatriation General Hospital, University of Western Australia, Nedlands, Western Australia 6009

LOUIS HERZBERG

A.F.P. IN AMNIOTIC FLUID AND SERUM

SIR,-Dr Weiss and colleagues (April 1,

717), after results (A.F.P.) remarking false-positive alpha-fetoprotein were uncommon, quoted our false-positive-rate as 9-13%. This figure was a printing error in the abstract of one of our papers.’ As stated clearly in the text, the false-positive-rate was actually 0.15%. Our experience now exceeds 10 000 cases and p.

that

this rate is now 0.1) according to the figures presented in the table and the usual t-test for independent samples.2 However, this test is inappropriate because the variances of the two samples are statistically different (p

A.F.P. in amniotic fluid and serum.

1098 showed a slightly enlarged heart with opacities at the right lung base suggestive of post-radiation fibrosis (she had had radiotherapy post-maste...
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