propylthiouracil and Arrhythmias--Cardiac

Topics: Adult; Anti-Arrhythmia Agents; Antithyroid Agents; Anxiety; Arrhythmias, Cardiac; Dyspnea; Graves Disease; Humans; Hypokalemic Periodic Paralysis; Malaysia; Male; Methimazole; Muscle Weakness; Neurologic Examination; Potassium; Propranolol; Propylthiouracil; Sleep Initiation and Maintenance Disorders; Tremor; Weight Loss

Amiodarone-induced thyrotoxicosis (AIT) is a difficult management problem about which there are little published data. We examined whether continuing amiodarone or differentiating AIT into 2 subtypes affected outcome.. The type and duration of antithyroid treatment and response were recorded in a consecutive series of 28 cases. Comparisons were made between those in whom amiodarone either was continued or stopped and between those with either possible type 1 or type 2 AIT. Of the 28 cases, 5 had spontaneous resolution of AIT; 23 received carbimazole (CBZ) alone as first-line therapy. Eleven achieved long-term euthyroidism off CBZ or on a maintenance dose. Five became hypothyroid and required long-term thyroxine. Five relapsed after stopping CBZ treatment and were rendered euthyroid with either long-term CBZ (n=3) or radioiodine (n=2). Four were intolerant of CBZ and received propylthiouracil (PTU), with good effect in 3. One was resistant to thionamide alone (CBZ then PTU) and responded to adjunctive steroids. No difference in presentation or outcome was noted between those in whom amiodarone was continued or stopped or between possible type 1 or type 2 AIT.. Continuing amiodarone has no adverse influence on response to treatment of AIT. First-line therapy with a thionamide alone is appropriate in iodine-replete areas, thus avoiding potential complications of other drugs. Differentiating between 2 possible types of AIT does not influence management or outcome.

Topics: Aged; Amiodarone; Arrhythmias, Cardiac; Autoantibodies; Carbimazole; Cohort Studies; Female; Humans; Iodine Radioisotopes; Male; Middle Aged; Propylthiouracil; Retrospective Studies; Steroids; Thyrotoxicosis; Thyrotropin; Thyroxine; Treatment Outcome; Triiodothyronine

1. It has been postulated that stimulation of myocardial alpha-adrenoceptors is one of the primary mediators of the dysrhythmias which occur during periods of myocardial ischaemia and reperfusion. This study examines arrhythmogenesis during coronary artery occlusion and reperfusion in isolated perfused rat hearts from control animals and from rats with enhanced myocardial alpha-adrenoceptor responsiveness. 2. Rats were administered propylthiouracil (PTU) in their drinking water for 8 weeks. This treatment resulted in an enhanced responsiveness of isolated left atria to the alpha-adrenoceptor agonist phenylephrine compared with atria from control animals. 3. In Langendorff-perfused isolated hearts, the spontaneous rate of contraction was significantly lower in the PTU-pretreated group than in either age-matched or weight-matched controls. Occlusion of the left anterior descending artery (LAD) for 25 min resulted in ventricular tachycardia (VT) of similar incidence and duration in all groups and ventricular fibrillation (VF) in both control groups but not the PTU-pretreated group. 4. Following the 25-min ischaemic period the myocardium was reperfused for 10 min. The incidence and duration of VT and VF during this period was similar in all groups except that the duration of VF in the PTU-pretreated group was significantly lower than in controls. 5. In perfused hearts paced at 4 Hz, the incidence and duration of dysrhythmias during ischaemia and reperfusion was again similar in all groups, only the duration of VF being affected (reduced) by PTU-pretreatment. 6. In conclusion, this study does not lend support to the hypothesis that myocardial alpha-adrenoceptors have a primary role in arrhythmogenesis, but the data would support a role for these receptors in myocardial protection.

Topics: Adrenergic alpha-Agonists; Animals; Arrhythmias, Cardiac; Atrial Function, Left; Male; Myocardial Ischemia; Myocardial Reperfusion; Myocardium; Phenylephrine; Propylthiouracil; Rats; Rats, Wistar; Receptors, Adrenergic, alpha

Topics: Anemia; Arrhythmias, Cardiac; Female; Goiter; Humans; Hypercalcemia; Hyperthyroidism; Iodine Radioisotopes; Middle Aged; Propranolol; Propylthiouracil; Thyroxine

Topics: Angiocardiography; Animals; Aorta, Thoracic; Arrhythmias, Cardiac; Autopsy; Coronary Angiography; Coronary Vessels; Death, Sudden; Diet, Atherogenic; Disease Models, Animal; Electrocardiography; Heart; Heart Conduction System; Lidocaine; Lung; Male; Myocardium; Propylthiouracil; Radiation Effects; Swine; Ventricular Fibrillation

Topics: Adult; Arrhythmias, Cardiac; Electrocardiography; Heart Block; Heart Conduction System; Humans; Hypercalcemia; Hyperthyroidism; Male; Propylthiouracil