Cardiac Glycosides: What You Need to Know

Introduction

Cardiac glycosides are a class of medications that have been used for centuries to treat heart conditions, particularly heart failure and certain types of arrhythmias. The most well-known cardiac glycoside is digoxin, derived from the foxglove plant (Digitalis purpurea).

How Do Cardiac Glycosides Work?

These drugs work by inhibiting the sodium-potassium ATPase pump, which leads to an increase in intracellular calcium in heart muscle cells. This results in: - Stronger heart contractions (positive inotropic effect), which helps improve the pumping ability of the heart in cases of heart failure. - Slower heart rate (negative chronotropic effect), useful in managing arrhythmias such as atrial fibrillation.

Medical Uses

Cardiac glycosides, especially digoxin, are used for: 1. Heart Failure – Helps increase the force of contractions and improve symptoms. 2. Atrial Fibrillation and Atrial Flutter – Helps control heart rate in these arrhythmias.

Potential Risks and Side Effects

Although cardiac glycosides are effective, they come with significant risks, especially toxicity. Signs of digoxin toxicity include: - Nausea, vomiting, and loss of appetite - Confusion, dizziness, or hallucinations - Vision disturbances (seeing halos around lights) - Irregular heart rhythms, which can be dangerous

Important Considerations

• Drug Interactions: Cardiac glycosides interact with many other medications, including diuretics, which can alter potassium levels and increase toxicity risk.
• Monitoring: Blood levels of digoxin should be carefully monitored to prevent toxicity.
• Kidney Function: Since digoxin is excreted through the kidneys, patients with reduced kidney function need dose adjustments.

Conclusion

Cardiac glycosides, particularly digoxin, remain valuable in heart failure and arrhythmia management, but they require careful monitoring due to their narrow therapeutic index. Always consult a cardiologist before using these medications.

Source recommendations

1. American College of Cardiology/American Heart Association Guidelines on Heart Failure

1. https://www.ahajournals.org/doi/10.1161/CIR.0000000000001063
2. https://www.acc.org/Guidelines
3. https://www.jacc.org/doi/10.1016/j.jacc.2023.12.024
4. https://www.acc.org/education-and-meetings/products-and-resources/features/global-cv-institute/heart-failure-guidelines
5. https://professional.heart.org/en/science-news/-/media/832EA0F4E73948848612F228F7FA2D35.ashx

2. European Society of Cardiology Guidelines for the Diagnosis and Treatment of Acute and Chronic Heart Failure

1. https://www.escardio.org/Guidelines/Clinical-Practice-Guidelines/Acute-and-Chronic-Heart-Failure
2. https://pubmed.ncbi.nlm.nih.gov/34447992/
3. https://academic.oup.com/eurheartj/article/42/36/3599/6358045
4. https://www.escardio.org/Guidelines/Clinical-Practice-Guidelines/Focused-Update-on-Heart-Failure-Guidelines
5. https://pubmed.ncbi.nlm.nih.gov/27206819/

3. American Heart Association Guidelines for the Management of Atrial Fibrillation

1. https://www.ahajournals.org/doi/10.1161/CIR.0000000000001193
2. https://professional.heart.org/en/science-news/2023-acc-aha-accp-hrs-guideline-for-the-diagnosis-and-management-of-atrial-fibrillation
3. https://www.heart.org/en/health-topics/atrial-fibrillation
4. https://pubmed.ncbi.nlm.nih.gov/38033089/
5. https://www.heart.org/en/health-topics/atrial-fibrillation/treatment-and-prevention-of-atrial-fibrillation/treatment-options-of-atrial-fibrillation-afib-or-af