title: Measurement of cardiac muscle relaxation in hypothyroidism.
abstract: The isovolumetric relaxation time of the left ventricle (IRT) in 20 hypothyroid patients (133 +/- (SE of mean) 4 ms) was significantly longer than that in 23 normal subjects (95 +/- 3 ms). During a trial of thyroxine replacement the  IRT in 12 hypothyroid patients fell from 143 +/- 4 ms to 107 +/- 4 ms. The IRT seems to be a useful index of end-organ function in hypothyroidism.
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D005260:Female; D006339:Heart Rate; D006801:Humans; D007037:Hypothyroidism / Q000188:drug therapy / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction / Q000187:drug effects; D012026:Reflex, Stretch; D013974:Thyroxine / Q000494:pharmacology / Q000627:therapeutic use; D013995:Time
chemical_list: D013974:Thyroxine