Cardiac glycosides

Medications:

  • digoxin


What do cardiac glycosides treat?

  • heart failure (HF)

  • cardiogenic shock

  • a-fib

  • a-flutter


How do cardiac glycosides work?

  • causes a positive inotropic effect on heart

    • inotropic = force of contraction

    • positive inotropic = stronger heart contraction

  • negative chronotropic effect on heart

    • chronotropic = time/rate

    • negative chronotropic = slower rate, heart beats slower

  • negative dromotropic effect on heart

    • dromotropic = the conduction of the heart the electrical signals

    • negative dromotropic = slower impulse through AV node

stronger heart, slower beats, slower impulses


Side effects of cardiac glycosides:

  • TOXICITY

    • early toxicity signs: nausea & vomiting

    • mid-stage toxicity signs: vison changes (yellow/green halos OR blurred vision)

    • late toxicity signs: ECG changes (dysrhythmias)

    • Risks for developing digoxin toxicity:

      • electrolyte imbalances

        • low K+ (potassium)

        • low Mg (magnesium)

        • high Ca (calcium)

      • elderly patients

      • if a pt is taking CCB (calcium channel blockers)

    • ANTIDOTE for digoxin toxicity: digibind

  • bradycardia

  • headache


Nurse Role:

  • count apical pulse PRIOR to administering digoxin

    • HOLD medication if apical pulse (heart rate) is:

      • adult: pulse < 60

      • child: pulse < 70

      • infant: pulse < 90-100

  • therapeutic range: 0.5 - 2 ng/mL

  • educate on K+ RICH foods (potassium rich), IF pt is not eating k+ supplements

  • monitor K+ levels (3.5 - 5 mEq/L)

  • monitor ECG for changes

  • monitor electrolytes

    • Na: 135 - 145 mEq/L

    • K: 3.5 - 5 mEq/L

    • Phosphorus (P): 2.7 - 4.5 mEq/L

    • Mg: 1.3 - 2.1 mEq/L

    • Chloride (Cl): 97 - 107 mEq/L

    • Ca: 9 - 10.2 mg/dL

    • phosphate: 3 - 4.5 mg/dL