[Atrioventricular block after carotid pressure in hypothyroidism: normalisation after substitution treatment (author's transl)].

Severe auto-immune hypothyroidism, probably after hyperthyroidism, was diagnosed in a 79-year-old woman with hypothyroidism (T3 and T4 immeasurably low) without the classical signs of myxoedema heart. On carotid sinus pressure transitory first degree AV block occurred and, on one occasion, complete AV block. This response disappeared after substitution treatment for four weeks with 50 microgram L-thyroxine. Further examination half a year later, on a maintenance of 75 microgram thyroxine, also gave a negative response to carotid sinus pressure.