Diltiazem: Cardiac Medication Mini Series, Part 4

Understanding Diltiazem is an important part of your cardiac skillset. It’s indications range from blood pressure management, long term stable angina, to it’s mainstay in the hospital setting: acute rate control of arrhythmias with rapid ventricular rates. This episode will cover Diltiazem’s mechanism of action, its multiple indications for both acute and routine use, as well as important nursing considerations.

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Mechanism of Action

Effect on Cardiac Muscle

  • Diltiazem inhibits the influx of calcium during depolarization causing a significant negative chronotropic, and to a lesser degree, negative inotropic effect on cardiac muscle.
  • The AV node is highly sensitive to Diltiazem, which is why it is used for the treatments of tachyarrhythmias.

effect on smooth muscle

  • As a calcium channel blocker, Diltiazem also increases smooth muscle relaxation which produces arterial vasodilation and lower systemic vascular resistance.
  • It’s worth nothing that Diltiazem has a relative sensitivity to cardiac muscle over vascular smooth muscle


  • The primary use for diltiazem is for treating cardiac dysrhythmias with a rapid ventricular rate (i.e. afib, aflutter, and SVT)
  • Diltiazem can also be prescribed as an antihypertensive, althought it has mild antihypertensive effects compared to other calcium channel blockers
  • Diltiazem can be taken for long-term stable angina treatment

Side Effects

  • Hypotension due to arterial vasodilation
  • Bradycardia from negative chronotropic effect
  • Heart blocks due to the blocking of electrical impulses
  • Symptoms of heart failure, including increased peripheral edema

Mentioned in the episode

ICU Advantage on YouTube is a great resource for critical care medications

Former podcast guest, Dr. Eric Strong, has a great video about choosing antiarrhythmic medications