Supraventricular Arrhythmias: An Electrophysiology Primer

Carol Chen-Scarabelli, MSN, APRN, BC, CCRN

Disclosures

Prog Cardiovasc Nurs. 2005;20(1):24-31. 

In This Article

Treatment

Treatment of supraventricular arrhythmias varies according to rhythm, rate, and hemodynamic stability. Therapeutic modalities include pharmacologic therapy, electrical cardioversion, ablation, and/or pacing. Atrial pacing therapies (delivered by a dual chamber implantable cardioverter-defibrillator) are currently under investigation for use in the treatment and prevention of AT or AF.[28]

Regular, narrow QRS-complex tachycardias are almost certain to be supraventricular and are treated initially with vagal maneuvers.[14] However, wide QRS-complex tachycardia may be present in SVT with bundle-branch block or AV conduction over an accessory pathway, and alsoin ventricular tachycardia. Treatment for SVT vs. ventricular tachycardia is very different, and when in doubt, the patient should be treated as if ventricular tachycardia were present ( Table V , Table VI ).[14]

The traditional approach to the treatment of AF involves anticoagulation and antiarrhythmic pharmacologic agents. However, advances in knowledge and technology have resulted in the development and utilization of radiofrequency catheter ablation in or around the pulmonary veins, as well as the surgical Maze procedure, and more recently, antitachycardia pacing, atrial pacing, and atrial defibrillator therapies for the treatment and prevention of AF.[1] In patients with intractable arrhythmia and poor ventricular rate control (i.e., AF with rapid ventricular response refractory to pharmacologic therapy), AV nodal ablation may be employed to disconnect the atria from the ventricles. However, AV nodal ablation results in complete heart block and subsequently necessitates the implantation of a permanent pacemaker. It is important to recognize that this treatment option does not eliminate the symptoms associated with the loss of atrial output (atrial kick), nor the risk of stroke.[4] Thus the patient must remain on anticoagulation therapy since his/her underlying rhythm (beneath the paced rhythm) remains AF. Cardiac resynchronization therapy (also known as biventricular pacing) involves pacing both ventricles, to correct the mechanical dyssynchrony in patients with heart failure and conduction disorders. In the Biventricular Pacing After Ablate Compared With Right Ventricular Therapy (PAVE) trial—the first prospective, randomized study evaluating biventricular pacing after ablate and pace therapy—biventricular pacing resulted in statistically significant improvement in functional capacity (presented by Rahul Doshi, MD at the American College of Cardiology Annual Scientific Session, March 7-10, 2004; New Orleans, LA).

Preventive atrial pacing therapy is currently being investigated as a strategy to reduce the incidence of AF by either elimination of the triggers and/or modification of the substrate of AF. In comparison to ventricular pacing, atrial or dual-chamber pacing has been shown to prevent or delay progression to permanent AF in elderly patients.[4] Atrial resynchronization pacing is being studied in the treatment of patients with advanced atrial conduction delay. Pacing from different sites in the atria, specific pacing algorithms targeted at potential AF triggers, and pace termination of AT are strategies being incorporated into the newer implantable cardioverter-defibrillators and pacemakers. Atrial defibrillators are being investigated as a treatment modality for recurrent, symptomatic, and persistent AF.[3]

The surgical Maze procedure, creating division of the atria into zones, is highly effective in the treatment of AF, but its use is limited since it involves major thoracic surgery on cardiopulmonary bypass[2] and is usually done in conjunction with another procedure, such as mitral valve repair.

Pulmonary vein isolation/ablation of focal triggers of paroxysmal AF has a higher success rate in patients with a single focus vs. those patients with several areas of focal triggers. Potential complications of pulmonary vein ablation include: pulmonary vein stenosis, systemic embolization, pericardial effusion and tamponade, and phrenic nerve palsy.[3]

The use of hybrid therapy consisting of two or more treatment strategies may help reduce morbidity and mortality of AF. In elderly patients and those with heart failure, proarrhythmia risks from antiarrhythmic drug therapy may be reduced or eliminated with preventive antitachycardia pacing.[4]

Management of narrow QRS-complex tachycardia includes vagal maneuvers, intravenous adenosine (to aid in diagnosis of the rhythm), and nondihydropyridine calcium channel blockers.[14] Wide QRS-complex tachycardia of unknown origin is treated with amiodarone, or direct current cardioversion, if hemodynamically unstable.[14]

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