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Note: conundrums are not meant to have a “right” answer – they are to see how most people are practicing. Would love your comments also regarding your thought processes and the evidence behind your decisions. We can learn from each other!
You are seeing a 3 year old with 2nd lifetime episode of SVT. The patient has no other prior PMH, was not on any medications, was healthy prior, and does not have WPW. After 2 doses of properly administered adenosine, the patient is still in SVT. She is alert, not toxic, has good perfusion, and is not hypotensive.
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September 28, 2018 at 9:29 am
So I just gave a lecture on this. I think that you have to make a clinical determination of whether or not the patient either has a bypass track or is very likely to have a bypass track. A 3 year old in “SVT” is statistically very likely to be associated with a bypass track. Thus while you can give AV nodal blocking agents in the second line however you do run the risk if they then decide to go into atrial fibrillation of running into a problem. I would say a three-year-old who likely has suspected avrt my next line for a medication would probably be procainamide if they were unable to be converted with adenosine. I think also there’s a reasonable argument to just give the kid ketamine and perform an electrical cardioversion as this is much quicker and doesn’t have any of the potential side effects of anti-arrhythmic medication.
September 30, 2018 at 6:26 pm
A single institution retrospective cohort study of 179 pediatric patients found a 15% rate of refractory SVT after 2 doses of adenosine, with increased risk in infants (Lewis J, Arora G, et al, J Pediatr 2017;181:177). A variety of treatments were used including further adenosine doses, cardioversion (3 of 27 patients), digoxin & beta-blockers in infants and amiodarone & procainamide in older children. PALS algorithms recommend amiodarone or procainamide for refractory stable SVT, and cardioversion for unstable SVT. A small retrospective study of pediatric refractory SVT patients showed procainamide to be superior to amioadarone (Chang PM, Silka MJ, et al Circ Arrhythm Electrophysiol 2010;3:134). Hypotension and cardiovascular collapse are also rare but potential adverse effects of amiodarone (Saharan S, Balaji S, Ann Pediatr Cardiol 2015;8:50). Uptodate states that procainamide or amiodarone are used for adenosine-refractory SVT, with verapamil a possible option in older children (avoid in < 1yo), and sotalol (beta-blocker) an alternative in asymptomatic hemodynamically stable patients. Avoid digoxin, verapamil, and beta-blockers in WPW patients, and avoid adenosine in WPW patients with an irregular tachycardia. A recent Don’t Forget the Bubbles talk reviews reasons for adenosine failure, and advocates sotalol or amiodarone as second line therapy https://dontforgetthebubbles.com/svt-in-infants-at-dftb17/