Lifelong Learning and Self-Assessment

Tuesday, August 12, 2014

2015 LLSA Articles: Evaluation and Initial Treatment of Supraventricular Tachycardia

EM review courses are designed as study tools and should be read critically.  They are not intended to be all-inclusive and are not meant to define the standard of care for the clinical practice of EM. ABEM  does not endorse a specific research finding or treatment modality by virtue of its being the subject.

Patients with symptomatic tachycardias require immediate medical attention. Although it is commonly believed that a precise diagnosis of the tachycardia is necessary before therapy is initiated, immediate treatment can usually be tailored to the characteristics of the ventricular response. By focusing on the ventricular response, one can assign the seven clinically relevant supraventricular tachycardias to diag nostic and therapeutic groups on the basis of the rapidity of onset, the heart rate,
and the regularity of the tachycardia.

This em review course focuses on the initial diagnostic and therapeutic approach to supraventricular tachycardias and the ways of differentiating them from ventricular arrhythmias. Although atrial premature
contractions are technically not a supraventricular tachycardia, this abnormality is included in the current discussion because it is often part of the differential diagnosis of supraventricular tachycardias. Types of Supraventricular Tachycardias, Sinus tachycardia, by far the most common supraventricular tachycardia. Sinus tachycardia is gradual in onset and recession. The heart rate is regular and classically does not exceed 220 beats per minute minus the patient’s age.

In sinus tachycardia, P waves precede the QRS complex. Atrial fibrillation is the most common pathologic supraventricular tachycardia, affecting more than 3 million people in the United States and many more worldwide.

Risk factors for atrial fibrillation include older age, male sex, hypertension, and underlying cardiac disease. Atrial fibrillation is caused by multiple electrical wavelets appearing in the atria simultaneously, resembling the waves that would be produced if one dropped several pebbles in a bucket of water at the same time. The arrhythmia is considered to be acute when it develops spontaneously in a person previously in normal sinus rhythm.