Calcium Channel Blocker Overdose

First Things First (assess & treat for the following):

  • In 2004: 10,513 exposures, 62 fatalities
  • Patient may present in shock or with severe bradydysrhythmias—institute ABCs and ACLS protocols as needed.

Physiology of calcium

  • Myocardium
    • Calcium enters myocardial cells via voltage-gated calcium channels.
    • Entry triggers intracellular organelles to release calcium to affect excitation-contraction.
    • Entry also triggers SA node action potential generation.
    • Maintains fatty acid utilization by the myocardium
  • Smooth Muscle: Calcium influx maintains tone
  • Pancreas: Calcium mediates insulin release

Pathophysiology of calcium channel blockers

  • Calcium channel blockers inhibit calcium entry by maintaining Ca channel in the closed position.
  • In excess, calcium channel blockers cause toxicity characterized by bradycardia, conduction abnormalities and hypotension.
  • Can produce a DKA-like state with insulin deficiency, hyperglycemia, acidemia and shock
  • Also antagonize fast sodium channels, causing QRS prolongation

There's more to see -- the rest of this topic is available only to subscribers.

Last updated: April 12, 2010