COVERT HYPOTHYROIDISM WITH WEIGHT LOSS AND ATRIAL FIBRILLATION

SUMMARY Hypothyroidism may present with weight gain and/or cardiovascular manifestations such as bradycardia or cardiac failure, but has not previously been documented as presenting with atrial fibrillation and weight loss. Our case highlights the importance of thyroid function tests in heart failure and emphasises the importance of regular follow-up after irradiation to the thyroid.     

AMIODARONE IN ATRIAL FIBRILLATION

SUMMARY Oral amiodarone may be used in the prevention of recurrences of paroxysmal atrial fibrillation (AF) or in chronic AF following electrical cardioversion or for pharmacological cardioversion of AF. The use of amiodarone for rate control of AF is also discussed in this article. Recent reports have shown that low-dose amiodarone is effective in preventing recurrence following cardioversion,¹ but there have been no long-term controlled or comparative studies to support this. Thus amiodarone is not recommended as a first-line drug for preventing recurrences of AF. Results on the use of amiodarone in the prevention of paroxysmal AF have been equivocal; this may be attributed to differences in defining paroxysmal AF. The use of low-dose amiodarone, alone or in combination with a class I agent, may be beneficial in patients with AF but long-term studies to determine the safety and efficacy of the drug are required.     

AN ASSESSMENT OF POPULATION-BASED AND BAYESIAN METHODS TO INDIVIDUALIZE DIGOXIN DOSES SHORTLY AFTER THE START OF THERAPY FOR ATRIAL FIBRILLATION

The accuracy of population-based methods and of Bayesian analysis to predict individual digoxin pharmacokinetic variables have been evaluated by their ability to predict a measured peak and trough serum digoxin concentration. We studied 13 digitalized patients (three women) whose mean (range) age and weight was 65.8 (60-78) years and 76.6 (68-101.6) kg and who had stable renal function. The population-based methods (using a clearance of 48.87 + 0.87 x creatinine clearance in ml/h/kg and volume of distribution, in litres, of either 7.3 x weight (kg) or 269 + 3.12 x creatinine clearance) were more than adequate for clinical purposes. The mean prediction errors of a measured steady-state peak concentration from these two population methods were -0.074 and 0.013 microgram/l respectively, whilst those of a measured trough concentration were -0.058 and 0.005 microgram/l. Bayesian analysis, using a sample drawn 11 h after the dose on day five of therapy, gave overall the least biased and most precise of the revised estimates. The mean prediction errors of peak and trough values using this sample were 0.069 and -0.005 microgram/l respectively. As expected, the closer the sample was drawn to the time of the trough concentration the more precise were the Bayesian-derived predictions. The value of the Bayesian technique to individualize digoxin doses could not be validated because it was not possible to distinguish between this and the population methods.(ABSTRACT TRUNCATED AT 250 WORDS)     

氯沙坦对高血压并阵发性心房颤动病人左心房功能影响

目的通过超声心动图观察氯沙坦对高血压并阵发性心房颤动（房颤）病人左心房功能的影响,探讨房颤预防及治疗的方法。方法将76例高血压并阵发性房颤病人随机分为氯沙坦组（n=38）和非洛地平组（n=38）,选择20例健康成年人做对照组,分别在用药前和用药后4、12、24周行超声心动图检查。结果12周后氯沙坦组与治疗前比较及与非洛地平组同期治疗后比较,左心房前后径、左心房上下径、左心房最大容积均减小,心房充盈速度、左心房射血力均明显增加（F=23．83～35．84,q=3.036～18．528,P〈0．05、0．01）。氯沙坦组的窦性心律维持率高于非洛地平组（x^2=4．338、4．828,P〈0．05）。结论氯沙坦在改善高血压并阵发性房颤病人的左心房功能的同时,能有效维持窦性心律。     

RECENT ADVANCES IN THE NON-SURGICAL MANAGEMENT OF ATRIAL FIBRILLATION

Atrial fibrillation is the commonest clinical arrhythmia, and is associated with significant morbidity and mortality. The treatment of choice is to restore and maintain sinus rhythm. Although certain antiarrhythmic drugs are more effective than placebo in maintaining sinus rhythm, recurrence of atrial fibrillation post cardioversion remains common. The use of antiarrhythmic drugs can be associated with serious adverse effects due to their negative inotropic and proarrhythmic effects. Radiofrequency ablation of the AV junction is a safe and effective palliative treatment option in patients who have failed drug therapy. Ventricular rate control without the need for permanent pacing can be achieved by AV nodal modification using radiofrequency energy. There is also interest in the role of catheter ablation as a possible curative procedure for atrial fibrillation. Atrial pacing can reduce the incidence of atrial fibrillation in certain subgroups of patients. Finally, low energy intracardiac atrial defibrillation has been shown to be feasible in humans.     

ATRIAL FIBRILLATION IN THE ELDERLY: PHYSICIANS' ATTITUDES TO ANTICOAGULATION

SUMMARY The use of warfarin and aspirin for the primary prevention of stroke in elderly patients with atrial fibrillation (AF) is controversial. To establish current practice we circulated a questionnaire to 300 geriatricians (G) and 300 cardiologists (C). The response rates were 47% G and 51% C. Most physicians prescribed warfarin in AF associated with mitral stenosis (G vs C, 86% vs 89%, NS). Cardiologists were more likely to prescribe warfarin in AF associated with dilated cardiomyopathy (G vs C, 52% vs 86%, P<0.01). A minority would prescribe warfarin in aortic valve disease and AF (G vs C, 37% vs 24%, P<0.05) and lone AF (G vs C, 10% vs 26%, P<0.01). Aspirin was favoured in aortic valve disease and lone AF. The cardiologists were less reluctant to use warfarin in the young and more likely to electrically cardiovert the young with chronic AF.     

经心外膜心房迷宫式射频消融心房纤颤

目的：探讨经心外膜迷宫式射频消融治疗心房外颤的可行性。方法：6例风心病会共房颤患者在瓣膜置换术或分离术的同时分别环行消融左右心耳根部及其间横窦、上下胜静脉之间及右房前壁和冠状窦。结果：6例患者本后均恢复窦性心律。术后随访为12～20个月，除1例房颤复发外，余均维持窦性心律。结论：本方法可以达到治疗房颤的目的。     

ACUTE ADMISSIONS WITH ATRIAL FIBRILLATION IN A BRITISH MULTIRACIAL HOSPITAL POPULATION

SUMMARY To assess the clinical characteristics and management of patients with atrial fibrillation (AF), we performed a prospective survey of all acute medical admissions over six months to our hospital. Of 7451 such admissions, 245 had AF (110 male, 135 female; mean age 74.4 years). Of these, 213 were Caucasian, 10 black/Afro-Caribbean and 22 Asian. Complete data were available for 185 patients. Of these, 82 had newly diagnosed AF, 83 had previous chronic AF and 20 had paroxysmal AF. The main presenting features was dyspnoea, stroke and syncope. A history of ischaemic heart disease was present in 64, heart failure in 46, hypertension in 51 and rheumatic heart disease in 13, while 31 had a previous stroke. Chest X-ray showed cardiomegaly and pulmonary oedema in 121 patients, but was normal in 28. Echocardiography showed poor cardiac function in eight patients and enlarged left atria in five. Only 28% of those with previously diagnosed AF were on anticoagulation. Of the newly diagnosed patients, only 18% were started on anticoagulants. Cardioversion was attempted or planned in only 6%. The primary diagnosis on discharge was heart failure in 45, stroke in 24 and myocardial infarction in 12. AF remains a common arrhythmia among acute medical admissions and is commonly associated with heart failure and a high mortality. There is still a reluctance to start anticoagulant therapy or to perform cardioversion in such patients.     

缬沙坦对高血压病伴阵发性房颤患者P波离散度的影响

目的　研究缬沙坦对高血压病伴阵发性房颤 (PAF)患者P波最大时限 (Pmax)和P波离散 (Pd)的影响 ,探讨缬沙坦的抗心律失常效应。方法　将 46例高血压病伴PAF患者随机分成缬沙坦治疗组 (2 3例 )和对照组 (2 3例 )。另设正常人 2 0例 (正常组 )为对照。在服药前、服药 4月分别测量Pmax及Pd ,并观察治疗后PAF发作情况。结果　高血压病伴PAF者Pmax及Pd分别为 (12 8 .3 3± 8. 49)ms、(4 6. 63± 9. 3 3 )ms ,均较正常人 [(10 2 . 9± 8. 61)ms、(2 8. 0 5± 7. 0 9)ms ,P均 <0 . 0 5 ]明显延长。服药第 4个月治疗组Pmax及Pd较治疗前明显缩短 (P均 <0 . 0 5 ) ,较对照组也明显缩短 (P <0 . 0 5 )。治疗第 4个月时治疗组PAF发作减少 10例 ,而对照组 5例有效。结论　高血压病伴PAF患者Pmax、Pd较正常人增大 ,缬沙坦可缩短Pmax及Pd并可能减少PAF的发作。