Adenosine Pharmacodynamics

By behereaxum

Summary

A patient's heart is suddenly racing — a re-entrant SVT. The nurse reaches for adenosine.

Chapters

  1. A patient's heart is suddenly racing (0s)
  2. Adenosine binds A-2 receptors on the (5s)
  3. Before the drug, electrical signals race (15s)
  4. Re-entrant tachycardias depend on a self-sustaining (21s)
  5. Adenosine's half-life is under ten seconds, (31s)
  6. Common side effects include facial flushing, (37s)
  7. Avoid it in asthma, in second (42s)
  8. Give it as a rapid IV (47s)
  9. Start with a six milligram rapid (51s)

Transcript

A patient's heart is suddenly racing — a re-entrant SVT. The nurse reaches for adenosine. Adenosine binds A-2 receptors on the AV node, opening potassium channels so potassium flows out, hyperpolarizing the cells and slowing how fast they can fire. Before the drug, electrical signals race through the AV node. After, conduction is transiently blocked. Re-entrant tachycardias depend on a self-sustaining loop through the AV node. That brief block breaks the loop, letting the sinus node retake control and restore a normal rhythm. Adenosine's half-life is under ten seconds, so its effect appears and vanishes almost instantly. Common side effects include facial flushing, chest tightness, and a brief sense of impending doom. Avoid it in asthma, in second or third-degree heart block, and with dipyridamole. Give it as a rapid IV push, immediately followed by a saline flush. Start with a six milligram rapid push; if the rhythm persists, follow with twelve. Because the effect is so fast and brief, run continuous monitoring and warn your patient first. Knowing the pharmacodynamics is what keeps dosing safe.