What is the best immediate treatment for supraventricular tachycardia if vagal maneuvers have failed?

The best immediate treatment for supraventricular tachycardia (SVT) after vagal maneuvers have failed is the administration of adenosine, specifically 6 mg by rapid intravenous infusion. Adenosine is an effective and fast-acting drug that works by temporarily blocking conduction through the atrioventricular (AV) node, which can help restore normal sinus rhythm in patients experiencing SVT.

The rapid infusion of adenosine is critical, as it needs to be administered quickly to effectively interrupt the reentrant circuit responsible for the SVT. The onset of action occurs within seconds, providing a rapid response in emergency situations.

Other medications and interventions might be effective in managing different forms of tachycardia, but adenosine stands out for its rapid action specifically in the context of SVT. Various antiarrhythmic drugs, such as ibutilide, are generally reserved for other types of arrhythmias, such as atrial fibrillation or flutter, and are not typically the first-line treatment for acute SVT. Similarly, procainamide is used in wider complex tachycardia rather than for simple SVT management due to its slower onset and potential systemic effects. The option for immediate direct current cardiov