Supraventricular and ventricular arrhythmias: medical management Paul Venables David R Tomlinson Abstract Cardiac arrhythmia results in significant morbidity and mortality in the western world and presents an ever-increasing economic burden on health services. Annually in the UK, around 1% of the NHS budget (£1 billion) is spent on treating AF. 1 Optimal heart rhythm management may not only improve patients’ quality of life, but timely diagnosis, treat- ment and specialist referral of patients with arrhythmias may permit the provision of both cost-effective and life-saving treatments. The accurate diagnosis of patients presenting acutely with arrhythmias requires skill in ECG interpretation. However, non-specialists can readily apply the simple principles that underline safe and effective management of such patients. An additional understanding of arrhythmia pathogenesis and basic pharmacology are all that is required to achieve a high degree of competence in all emergency room management scenarios and in the long-term care of patients with arrhythmia. This article aims to provide the reader with a ‘toolkit’ for the medical management of cardiac arrhyth- mias, with a particular focus on the acute setting. The indications for other important therapies, such as catheter ablation and implantable car- dioverter defibrillators, are outlined as appropriate, but these subjects are covered elsewhere. Keywords antiarrhythmic drugs; atrial fibrillation; atrial flutter; atrial tachycardia; atrioventricular tachycardia; AV nodal re-entrant tachycardia; pre-excited AF; supraventricular tachycardia; ventricular tachycardia General approach to arrhythmia diagnosis History Common symptoms include palpitations, breathlessness, fatigue and chest tightness/pain consistent with angina, but these are poorly predictive of whether the arrhythmia is ventricular or supraventricular in origin. The nature of the heart rhythm (regular or irregular) during palpitations may be useful in differentiating between regular tachycardias and arrhythmias such as ectopic beats and atrial fibrillation (AF). Genuine arrhythmias will be instantaneous in onset and offset, but can nevertheless present as an incidental finding in an asymptomatic patient. Haemodynamic compromise resulting in presyncope or syncope occurs more frequently with ventricular arrhythmias, but also occurs in 15% of patients with otherwise benign supraventricular tachycardias (SVTs), generally at either the onset or termination of the arrhythmia. Syncope may also herald potentially life-threatening disease, such as in pre-excited AF, or point towards the presence of severe structural heart disease (e.g. aortic stenosis or hypertrophic cardiomyopathy). Finally, arrhythmias resulting in persistent elevation of the ventricular rate may present as congestive heart failure (CHF), secondary to tachycardia-induced cardiomyopathy; such deterioration in left ventricular (LV) systolic function usually takes several weeks to occur. The background medical history may provide an indication of the likely source of the arrhythmia; ventricular tachycardia (VT) occurs more frequently with a history of prior myocardial infarction (MI), pre-existing structural heart disease or CHF. Acute arrhythmias may be precipitated by intercurrent illness (e.g. AF in the setting of pneumonia, thyrotoxicosis, pulmonary embolism or pericarditis, or secondary to myocardial ischaemia). Some medications may be pro-arrhythmic, and a family history of arrhythmia or sudden cardiac death (SCD) should always be noted. Physical examination In the baseline state, examination is usually normal. However, during symptomatic arrhythmia, examination of the jugular venous pressure (JVP) can suggest atrioventricular (AV) disso- ciation and possible VT (cannon ‘a’ waves). Acutely, attention must be paid to signs of cardiac decompensation, particularly pulmonary oedema, which is suggestive of serious underlying structural heart disease. Investigations  A 12-lead ECG during tachycardia and during IV adenosine administration provides the optimal diagnostic information (see below).  ECG following tachycardia termination e delta waves may be evident and, in cases of suspected VT, evidence of acute or prior MI.  Blood screening for metabolic and endocrine abnormalities.  Chest X-ray to exclude concomitant pulmonary pathology in selected patients.  Transthoracic echocardiography should be undertaken in all patients and may be necessary in the acute phase if severe structural heart disease is suspected.  Ambulatory rhythm monitoring may be required for arrhythmia documentation in patients with infrequent symptoms.  An implantable loop recorder may be used in patients with recurrent but infrequent syncope where arrhythmia is sus- pected but has not yet been documented. Pathogenesis of cardiac arrhythmias Re-entry, triggered activity and increased automaticity underlie the pathogenesis of cardiac arrhythmias (Figure 1). Paul Venables BM MRCP is a Cardiology Specialist Registrar at the South West Cardiothoracic Centre, Derriford Hospital, Plymouth, UK. Competing interests: none declared. David R Tomlinson BSc MD MRCP is a Consultant Cardiologist and Electrophysiologist at the South West Cardiothoracic Centre, Derriford Hospital, Plymouth, UK. Competing interests: none declared. ARRHYTHMIAS AND ELECTROPHYSIOLOGY MEDICINE 38:9 515 Ó 2010 Elsevier Ltd. All rights reserved.