Tachycardia With a Pulse Flashcards

A 9-year-old with SVT receives adenosine via a peripheral IV in the antecubital fossa. The rhythm does not convert. What is the most likely reason for failure?

Answer: Adenosine was not followed by a rapid saline flush

Failure to immediately flush adenosine with normal saline allows the drug to be inactivated before reaching the central circulation due to its 10-second half-life.

In pediatric tachycardia assessment, what does the PALS algorithm define as the primary distinction between 'stable' and 'unstable' tachycardia?

Answer: Presence or absence of signs of cardiopulmonary compromise

PALS classifies tachycardia as unstable when there are signs of cardiopulmonary compromise such as poor perfusion, hypotension, or altered mental status.

A 1-year-old infant is in SVT with a rate of 260 bpm and is feeding poorly with mottled skin. There is no IV or IO access. What is the most appropriate immediate step?

Answer: Apply ice bag to the face briefly to stimulate the diving reflex

Ice application to the infant's face stimulates the diving reflex as a vagal maneuver and can be performed immediately without IV access.

Which statement correctly describes ventricular tachycardia (VT) with a pulse in a pediatric patient compared to SVT with aberrancy?

Answer: VT more commonly shows AV dissociation and fusion beats on ECG

AV dissociation (P-waves unrelated to QRS complexes) and fusion beats are classic ECG findings that favor VT over SVT with aberrancy.

For a child with SVT who has IV access established, at what site should adenosine ideally be injected for fastest effect?

Answer: A large proximal vein such as the antecubital or central line

Adenosine should be injected into a large proximal vein (or central line) to minimize transit time to the heart given its ultra-short half-life.

Which of the following best describes the mechanism by which adenosine terminates SVT?

Answer: It transiently blocks AV nodal conduction, interrupting the re-entrant circuit

Adenosine transiently blocks the AV node, interrupting the re-entry circuit that sustains SVT and allowing the sinus node to re-establish control.

A child with tachycardia has a QRS duration of 0.08 seconds. How should this QRS be classified and what does it suggest?

Answer: Narrow QRS; suggests a supraventricular origin of the tachycardia

A QRS duration less than 0.09 seconds is considered narrow in children, indicating conduction through the normal His-Purkinje system and suggesting a supraventricular origin.