In the present study: (a) physiopathology, (b) clinics, and (c)
therapy of cardiothyreosis are discussed. (a) The
hyperkinetic syndrome, the earliest clinical sign in
thyrotoxicosis (vasodilatation, increase in inotropism, automatism, etc.), is mediated by a two-fold increase in the number of beta-receptors, and supported by an adequate synthesis of
ATP and creatinphosphate (CP) in the young and, to a lesser extent, in the elderly. Genetical heart reserves are mobilized, thus significantly increasing the number and the size of mitochondria and also the enzymatic equipment (such as: the
alpha-glycerophosphate-dehydrogenase, malic, pentosic cycles, etc.), a.s.o. Due to an excessive
adrenergic action (glycogenolysis, an excessive oxygen consumption, up to
necrosis, the
ATP and CP syntheses dramatically drop; the
phosphorus/
oxygen ratio decreases to 2 (normal = 4). In this condition, the high functional cardiovascular performances are also impaired (the submaximal effort capacity is attained at a smaller and smaller oxygen consumption;
Propranolol 2 mg i.v. decreased the cardiac output by above 30% (vs 10%--normal); electrocardiogram presents aspects of "
coronary disease",
tachycardia, etc.). An ultrastructural damage occurs: from "
mitochondrial disease", partial lysis of myofibrils, to myofibrosis (revealed postmortem), in spite of a reduced degree of
coronary atherosclerosis. Ultrastructural and biochemical experimental data support this point of view. (b) The incidence, precocity and severity of the thyrotoxic heart increase with age and the existence of a previous cardiovascular pathology. Cardiothyreosis is not present under 27 years; in 4,353 patients its incidence is of 25% (
arrhythmia--21%,
heart failure--12%, coronary insufficiency--1-3%). Of a major interest are
tachyarrhythmias which may lead to a high mortality by hypodiastolic
congestive heart failure,
heart failure with secondary
hyperaldosteronism, thromboembolic episodes and
ventricular fibrillation.
Thyrotoxicosis favours the disease of papillary muscles--mitral
prolapse and insufficiency, reversible especially in children. (c) The treatment of thyrotoxic heart is an etiologic one (medical, surgical, radioactive--the last two being preferable after the adequate medical
therapy). In particular, cardiothyreosis requires a reinforced irradiation (10,000 rads instead of 7,000 rads) in smaller 131I doses. The protection against the increased nocivity of
catechols in
thyrotoxicosis is very important (which explains the high mortality in the
thyrotoxic "storm") and requires
propranolol; doses above 2 mg/kilo body/day are recommended. In the elderly, the sensitivity to
propranolol decreases:
verapamil i.v. is more efficient in paroxysmal
tachyarrhythmias (
flutter, atrial fibrillation) and in those occurring intra-operatively during
halothane narcosis. The
anticoagulant therapy is administered in
tachyarrhythmias with high ventricular rate, especially in the elderly, to avoid the embolic risk, higher in defibrillation condition.(ABSTRACT TRUNCATED AT 400 WORDS)