The effects of L-thyroxine treatment on QT dispersion in primary hypothyroidism.

Hypothyroidism has various cardiovascular manifestation and exhibits electrocardiographic change. The QT dispersion on surface ECG reflects regional variations in myocardial repolarization. The effect of L-thyroxine treatment on ECG parameters, such as QT dispersion, in patients with primary hypothyroidism were investigated. This study involved 18 patients (3 men, 15 women, ages: 48+/-18 yr) with primary hypothyroidism. All patients were checked with a standard 12-lead ECG before and after L-thyroxine treatment. Various ECG parameters were then measured twice. The mean L-thyroxine treatment duration was 22+/-2.7 months. The mean thyroid-stimulating hormone levels of patients before and after therapy were 40.2+/-29.8 microU/mL, 3.6+/-4.6 microU/mL (p<0.001) and free-T4 levels were 0.44+/-0.38 ng/dL, 1.51+/-0.39 ng/dL (p<0.001). After L-thyroxine treatment, QT interval (395+/-42 vs. 380+/-24 msec, p<0.05), QTc interval (434+/-32 vs. 417+/-23 msec, p<0.05), QT dispersion (45+/-23 vs. 30+/-13 msec, p=0.008), QTc dispersion (49+/-23 vs. 32+/-14 msec, p=0.005) significantly decreased. There were no significant changes in the PR and RR intervals, as well as the QRS duration. Our findings suggest that the thyroid hormone affects ventricular inhomogenicity, and that L-thyroxine replacement therapy may reduce malignant ventricular arrhythmia and sudden cardiac death in primary hypothyroidism.

A case of primary pericardial undifferentiated sarcoma.

Primary pericardial sarcomas are extremely rare. The authors report a case of a 46-yr-old woman in whom a large mediastinal mass was discovered. The patient presented with cough, dyspnea, and orthopnea. Diagnostic investigations, such as echocardiography, computed tomography, and exploratory thoracotomy provided the evidence of a large mass in the mediastinum, attached by a broad base to the superior portion of the pericardium. A excisional biopsy was performed, and histologic examination of a biopsy specimen showed undifferentiated sarcoma. However, the complete removal of the mass was impossible due to adhesion to the adjacent great vessels. After the completion of the chemotherapy the patient was completely asymptomatic. However, follow-up transesophageal echocardiography showed a residual 3 x 4 cm-sized mass. The patient received the radiotherapy with a total dose of 55 Gy over 6 weeks. At present, there is no evidence of disease progression.