Supraventicular tachycardia can be managed best by: September 2009
**Core Concept**
Supraventricular tachycardia (SVT) is a type of abnormal heart rhythm originating from the atria or the atrioventricular (AV) node. It is characterized by a rapid heart rate, typically exceeding 150 beats per minute, and can be life-threatening if left untreated. The management of SVT involves interrupting the re-entrant circuit that perpetuates the arrhythmia.
**Why the Correct Answer is Right**
The correct answer involves the use of vagal maneuvers to terminate SVT. Vagal maneuvers, such as the Valsalva maneuver, carotid massage, or immersion in cold water, stimulate the vagus nerve and increase parasympathetic tone. This increases the release of acetylcholine, which binds to muscarinic receptors in the AV node and slows conduction, thereby interrupting the re-entrant circuit and terminating the SVT. The use of vagal maneuvers is a first-line treatment for SVT and is often effective in restoring a normal heart rhythm.
**Why Each Wrong Option is Incorrect**
**Option A:** Adenosine is a correct treatment for SVT, but it is not the best initial approach. Adenosine works by transiently blocking AV nodal conduction, which can terminate the re-entrant circuit. However, it is typically used after vagal maneuvers have failed.
**Option B:** Digoxin is not an effective treatment for SVT. Digoxin increases the contractility of the heart and slows the heart rate, but it does not interrupt the re-entrant circuit that perpetuates SVT.
**Option C:** Beta-blockers are not the best initial treatment for SVT. While beta-blockers can slow the heart rate and reduce the frequency of SVT episodes, they do not interrupt the re-entrant circuit and may not be effective in terminating the arrhythmia.
**Clinical Pearl / High-Yield Fact**
Vagal maneuvers are a first-line treatment for SVT because they are non-invasive, easy to perform, and effective in restoring a normal heart rhythm. However, they may not be effective in all cases, and other treatments, such as adenosine or electrical cardioversion, may be necessary.
**Correct Answer: A. Vagal maneuvers are the best initial treatment for supraventricular tachycardia.**