propylthiouracil and Tachycardia--Supraventricular

A shortening of the atrial refractory period has been considered as the main mechanism for the increased risk of atrial fibrillation in hyperthyroidism. However, other important factors may be involved.. Our objective was to determine the activity of abnormal supraventricular electrical depolarizations in response to elevated thyroid hormones in patients without structural heart disease.. Twenty-eight patients (25 females, three males, mean age 43+/-11 yr) with newly diagnosed and untreated hyperthyroidism were enrolled in a prospective trial after exclusion of heart disease. Patients were followed up for 16 +/- 6 months and studied at baseline and 6 months after normalization of serum TSH levels.. The incidence of abnormal premature supraventricular depolarizations (SVPD) and the number of episodes of supraventricular tachycardia was defined as primary outcome measurements before the start of the study. In addition, heart rate oscillations (turbulence) after premature depolarizations and heart rate variability were compared at baseline and follow-up.. SVPDs decreased from 59 +/- 29 to 21 +/- 8 per 24 h (P = 0.003), very early SVPDs (so called P on T) decreased from 36 +/- 24 to 3 +/- 1 per 24 h (P < 0.0001), respectively, and nonsustained supraventricular tachycardias decreased from 22 +/- 11 to 0.5 +/- 0.2 per 24 h (P = 0.01) after normalization of serum thyrotropin levels. The hyperthyroid phase was characterized by an increased heart rate (93 +/- 14 vs. 79 +/- 8 beats/min, P < 0.0001) and a decreased turbulence slope (3.6 vs. 9.2, P = 0.003), consistent with decreased vagal tone. This was confirmed by a significant decrease of heart rate variability.. Hyperthyroidism is associated with an increased supraventricular ectopic activity in patients with normal hearts. The activation of these arrhythmogenic foci by elevated thyroid hormones may be an important causal link between hyperthyroidism and atrial fibrillation.

Topics: Action Potentials; Adult; Antithyroid Agents; Atrial Fibrillation; Carbimazole; Echocardiography; Electric Stimulation; Female; Heart Rate; Humans; Hyperthyroidism; Male; Middle Aged; Propylthiouracil; Tachycardia, Supraventricular

We present a case of thyroid storm manifesting as supraventricular tachycardia with cardiopulmonary dysfunction. Our patient presented with severe cardiopulmonary symptoms (tachycardia, respiratory distress, and pulmonary edema) refractory to standard medical treatment. When the diagnosis of thyroid storm was made and proper treatment initiated, our patient had a prompt and appropriate response.

Topics: Antithyroid Agents; Female; Humans; Intubation, Gastrointestinal; Middle Aged; Propylthiouracil; Pulmonary Edema; Respiratory Distress Syndrome; Tachycardia, Supraventricular; Thyroid Crisis; Treatment Outcome

Beta-blockers and calcium antagonists have been advocated for thyrotoxicosis induced tachyarrhythmias. Amiodarone is generally considered as contraindicated because of its high iodine content. Since amiodarone combined with propylthiouracil induced a greater fall in serum thyroid hormone concentrations than propylthiouracil alone, we treated 2 hyperthyroid patients with supraventricular arrhythmias by radioiodine (day 0) followed after 24 h by amiodarone and propylthiouracil. Serum T3 was normalized on day 2 (patient 1) and 3 (patient 2). Effective t1/2 of intrathyroidal 131I were 6.6 and 4.3 days (versus 5.9 days for 131I given alone). In patient 1, atrial fibrillation, reverted to sinus rhythm after verapamil and digoxin, and did not recur. In patient 2, conversion of atrial fibrillation to sinus rhythm occurred on day 11; from day 0 to day 11, ventricular rate decreased and was significantly correlated to T3 (r = 0.82; p < 0.05). In conclusion, amiodarone may be beneficial in thyrotoxicosis associated tachyarrhythmias, given with propylthiouracil 24 h after radioiodine, it did not decrease thyroid irradiation and rapidly decreased serum T3.

Topics: Adult; Aged; Amiodarone; Combined Modality Therapy; Female; Humans; Hyperthyroidism; Iodine; Iodine Radioisotopes; Male; Propylthiouracil; Tachycardia, Supraventricular; Thyroxine; Triiodothyronine