Measurement of cardiac muscle relaxation in hypothyroidism.Br Med J 1976; 1 doi: http://dx.doi.org/10.1136/bmj.1.6022.1366 (Published 05 June 1976) Cite this as: Br Med J 1976;1:1366
- J J Manns,
- A M Shepherd,
- J Crooks,
- D G Adamson
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.