Direct current cardioversion (DCC)

PERFECTING PROCEDURES

Direct current cardioversion (DCC)

Complications following DCC Rare (<1%) Healthcare worker defibrillation Aspiration Stroke Procedural ventricular fibrillation Post-procedure bradycardia (use a pacing defibrillator) Common (>1%) Skin erythema

Andrew D Staniforth

Abstract Direct current cardioversion is commonly used to restore sinus rhythm (SR) from atrial fibrillation and atrial flutter. Acute success is high (90%). The likelihood of maintaining SR is dependent upon the duration of arrhythmia and presence of structural heart disease.

Table 1

Keywords Atrial fibrillation; atrial flutter; DC cardioversion

defibrillation is preferable for operator safety; pads should be applied firmly to reduce burns (Table 1). The starting energy is usually 200 J, increasing to 360 J, biphasic and synchronized. There is limited evidence to suggest that anteroposterior paddle orientation is superior to antero-lateral. DCC should not be applied directly over a permanent pacemaker (PPM) or implantable cardioverter defibrillator (ICD); such devices must be checked after the procedure. Internal cardioversion is possible either via an ICD or using proprietary transvenous defibrillation catheters.

Introduction An electric current is passed through the heart, depolarizing all conducting tissue; arrhythmia is terminated and sinus rhythm (SR) re-emerges. The role of defibrillation in treating life-threatening arrhythmias is described elsewhere in international resuscitation guidelines.1

Direct current conversion (DCC) for atrial fibrillation (A-Fib) and atrial flutter (A-FL)2

Outcomes DCC for A-Fib has an acute success rate of 70e90%. However, the likelihood of maintaining sinus rhythm is related to the severity of underlying heart disease, the duration of A-Fib, or the existence of a correctable driver. Even when the patient is treated with amiodarone after the procedure, the likelihood of maintaining SR is modest (40e60% at 2 years).3,6 A

A rhythm-based approach carries no prognostic or stroke reduction benefit;3 its rationale is symptom relief alone.

Anticoagulation A-Fib and A-FL carry identical stroke risks. Patients should be anticoagulated for 3 weeks before DCC,4 unless this can be performed within 48 hours of the onset of arrhythmia. DCC for A-Fib that has lasted more than 48 hours carries a 1e5% risk of stroke; a clot in the atrial appendage can be identified by transoesophageal echocardiography (TOE) in these cases. Anticoagulation should be continued for 3e4 weeks following DCC, as the return of mechanical atrial systole lags behind electrical SR.

REFERENCES 1 Resuscitation Council (UK). Resuscitation guidelines. 2010, www. resus.org.uk. 2 ESC Task Force. Guidelines for the management of atrial fibrillation. Eur Heart J 2010; 31: 2369e429. 3 The RACE Investigators. A comparison of rate control and rhythm control in patients with recurrent persistent atrial fibrillation. N Engl J Med 2002; 347: 1834e40. 4 Bjerkelund CJ, Orning OM. The efficacy of anticoagulant therapy in preventing embolism related to DC electrical cardioversion of atrial fibrillation. Am J Cardiol 1969; 23: 208e16. 5 Boodhoo L, Bordoli G, Mitchell AR, Lloyd G, Sulke N, Patel N. The safety and effectiveness of a nurse led cardioversion service under sedation. Heart 2004; 90: 1443e6. 6 The SAFE-T Investigators. Amiodarone versus sotalol for atrial fibrillation. N Engl J Med 2005; 352: 1861e72.

Anaesthesia DCC requires sedation and analgesia; it is usually performed during a brief general anaesthetic. Conscious sedation is a safe alternative in selected patients.5

Technique DCC requires a fasted state and normal serum potassium. Digoxin toxicity carries a risk of procedural VF. Hands-free

Andrew D Staniforth BSc DM MRCP is Consultant Cardiologist, Nottingham University Hospitals NHS Trust, Nottingham, UK. Competing interests: none declared.

MEDICINE 42:10

628

Ó 2014 Elsevier Ltd. All rights reserved.