Emergency treatment for TGV –
**Core Concept**
Supraventricular tachycardia (SVT), also known as paroxysmal supraventricular tachycardia (PSVT), is a type of abnormal heart rhythm (arrhythmia) characterized by a rapid heart rate originating from above the ventricles. The goal of emergency treatment is to restore a normal heart rate and rhythm.
**Why the Correct Answer is Right**
The emergency treatment for SVT involves vagal maneuvers to try and restore a normal heart rate. This is achieved through the Valsalva maneuver, which involves forced expiration against a closed glottis, increasing intrathoracic pressure and stimulating the vagus nerve to slow the heart rate. If vagal maneuvers are unsuccessful, adenosine is the drug of choice for acute termination of SVT. Adenosine works by transiently blocking the AV node, interrupting the re-entrant circuit that maintains the tachycardia.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because beta-blockers are not the first-line treatment for SVT. While beta-blockers can slow the heart rate, they do not address the underlying cause of the arrhythmia.
**Option B:** This option is incorrect because calcium channel blockers (CCBs) are not typically used as first-line treatment for SVT. CCBs can be used in certain cases, but they are not as effective as adenosine in terminating SVT.
**Option C:** This option is incorrect because digoxin is not used in the acute management of SVT. Digoxin can be used to control ventricular rate in atrial fibrillation, but it is not effective in terminating SVT.
**Clinical Pearl / High-Yield Fact**
The "Vagal Maneuvers" acronym can help you remember the steps to try and restore a normal heart rate in SVT: V-A-L-S-A-L-V-A (Valsalva, Adenosine, Lidocaine, Sotalol, Adrenaline).
**Correct Answer:** D. Adenosine