cardiovascular disorders
Reentrant Supraventricular Tachycardias (SVT) Including Wolff Parkinson White Syndrome
Introduction
Reentrant supraventricular tachycardias (SVT) involve reentrant pathways with a component above the bifurcation of the His bundle. Patients have sudden episodes of palpitations that begin and terminate abruptly; some have dyspnea or chest discomfort. Diagnosis is clinical and by electrocardiography. Initial treatment is usually with vagotonic maneuvers. If these maneuvers are ineffective, treatment is with IVadenosineor nondihydropyridine calcium channel blockers for narrow QRS rhythms or for wide QRS rhythms known to be a reentrant SVT with aberrant conduction that requires atrioventricular nodal conduction.Procainamideoramiodaroneare effective for other wide QRS rhythms. Synchronized cardioversion can be done for all cases in which drugs are ineffective or there is hemodynamic instability. (See also Overview of Arrhythmias .) 