Myocardial ultrasonic tissue characterization in patients with thyroid dysfunction.
BACKGROUND
Structural myocardial abnormalities have been extensively documented in hypothyroidism. Experimental studies in animal models have also shown involvement of thyroid hormones in gene expression of myocardial collagen. This study was planned to investigate the ability of ultrasonic tissue characterization, as evaluated by integrated backscatter (IBS), to early identify myocardial involvement in thyroid dysfunction.


METHODS
We studied 15 patients with hyperthyroidism (HYPER), 8 patients with hypothyroidism (HYPO), 14 patients with subclinical hypothyroidism (SCH) and 19 normal (N) subjects, who had normal LV systolic function. After treatment, 10 HYPER, 6 HYPO, and 8 SCH patients were reevaluated. IBS images were obtained and analyzed in parasternal short axis (papillary muscle level) view, at left ventricular (LV) posterior wall. The following IBS variables were analyzed: 1) the corrected coefficient (CC) of IBS, obtained by dividing IBS intensity by IBS intensity measured in a rubber phantom, using the same equipment adjustments, at the same depth; 2) cardiac cyclic variation (CV) of IBS--peak-to-peak difference between maximal and minimal values of IBS during cardiac cycle; 3) cardiac cyclic variation index (CVI) of IBS--percentual relationship between the cyclic variation (CV) and the mean value of IBS intensity.


RESULTS
CC of IBS was significantly larger (p < 0.05) in HYPER (1.57 +/- 0.6) and HYPO (1.53 +/- 0.3) as compared to SCH (1.32 +/- 0.3) or N (1.15 +/- 0.27). The CV (dB) (HYPO: 7.5 +/- 2.4; SCH: 8.2 +/- 3.1; HYPER: 8.2 +/- 2.0) and the CVI (HYPO: 35.6 +/- 19.7%; SCH: 34.7 +/- 17.5%; HYPER: 37.8 +/- 11.6%) were not significantly different in patients with thyroid dysfunction as compared to N (7.0 +/- 2.0 and 44.5 +/- 15.1%).


CONCLUSIONS
CC of IBS was able to differentiate cardiac involvement in patients with overt HYPO and HYPER who had normal LV systolic function. These early myocardial structural abnormalities were partially reversed by drug therapy in HYPER group. On the other hand, although mean IBS intensity tended to be slightly larger in patients with SCH as compared to N, this difference was not statistical significant.
Romano
Minna M D
MM
Division of Cardiology, Department of Internal Medicine, University Hospital, Medical School of Ribeirão Preto, University of São Paulo, Brazil.
Maciel
Léa M Z
LM
Almeida-Filho
Oswaldo C
OC
Pazin-Filho
Antonio
A
Schmidt
André
A
Maciel
Benedito C
BC
D000328:Adult; D013956:Antithyroid Agents / Q000627:therapeutic use; D003937:Diagnosis, Differential; D015150:Echocardiography, Doppler; D005260:Female; D006331:Heart Diseases / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology; D006801:Humans; D006980:Hyperthyroidism / Q000150:complications* / Q000188:drug therapy; D007037:Hypothyroidism / Q000150:complications* / Q000188:drug therapy; D008297:Male; D008713:Methimazole / Q000627:therapeutic use; D008875:Middle Aged; D012720:Severity of Illness Index; D013599:Systole / Q000502:physiology; D013974:Thyroxine / Q000627:therapeutic use; D016277:Ventricular Function, Left / Q000502:physiology
D013956:Antithyroid Agents; D008713:Methimazole; D013974:Thyroxine