Drugs used in congestive heart failure (CHF) aim to improve cardiac function, reduce symptoms, and enhance survival by targeting various physiological pathways involved in heart failure.
Pathophysiology of Congestive Heart Failure
CHF results from the heart's inability to pump sufficient blood to meet the body's needs.
It involves complex mechanisms, including neurohormonal activation (e.g., renin-angiotensin-aldosterone system), fluid retention, and ventricular remodeling.
Classification of Drugs Used in CHF
These medications are categorized based on their primary mechanism of action:
A) Cardiac Glycosides
Mechanism of Action:
Cardiac glycosides inhibit the Na⁺/K⁺-ATPase pump, leading to an increase in intracellular calcium in cardiac cells.
This enhances myocardial contractility (positive inotropic effect) and modulates autonomic tone, reducing heart rate and improving cardiac output.
Common Drugs:
Digoxin
Digitoxin
Uses:
Improve symptoms in heart failure.
Rate control in atrial fibrillation and other supraventricular tachycardias.
Side Effects:
Gastrointestinal disturbances (e.g., nausea, vomiting).
Cardiac arrhythmias (e.g., ventricular tachycardia, atrioventricular block).
Visual disturbances (e.g., yellow-green halos).
B) Natriuretic Peptides
Mechanism of Action:
Natriuretic peptides promote vasodilation and natriuresis (excretion of sodium in urine), reducing blood volume and systemic vascular resistance.
This alleviates the workload on the heart.
Common Drugs:
Nesiritide
Bosentan
Tezosentan
Uses:
Acute decompensated heart failure (Nesiritide).
Pulmonary arterial hypertension (Bosentan, Tezosentan).
Side Effects:
Hypotension.
Headache.
Electrolyte imbalances.
C) Endothelin Receptor Antagonists
Mechanism of Action:
These agents block endothelin-1 receptors, which are potent vasoconstrictors.
By inhibiting these receptors, they cause vasodilation, reduce pulmonary vascular resistance, and alleviate symptoms of heart failure and pulmonary hypertension.
Common Drugs:
Bosentan
Tezosentan
Uses:
Pulmonary arterial hypertension.
Off-label use in certain cases of heart failure with preserved ejection fraction.
Side Effects:
Liver function abnormalities.
Peripheral edema.
Anemia.
Teratogenic effects (contraindicated in pregnancy).
Class | Mechanism of Action | Common Drugs | Uses | Side Effects |
Cardiac Glycosides | Inhibits Na⁺/K⁺-ATPase pump; increases intracellular calcium; enhances contractility | Digoxin, Digitoxin | Improves symptoms in heart failure; rate control in atrial fibrillation | GI disturbances, arrhythmias, visual disturbances |
Natriuretic Peptides | Promotes vasodilation and natriuresis; reduces blood volume and vascular resistance | Nesiritide, Bosentan, Tezosentan | Acute heart failure (Nesiritide); pulmonary hypertension | Hypotension, headache, electrolyte imbalances |
Endothelin Receptor Antagonists | Blocks endothelin-1 receptors; causes vasodilation, reduces pulmonary vascular resistance | Bosentan, Tezosentan | Pulmonary hypertension; sometimes in heart failure | Liver issues, peripheral edema, anemia, teratogenic effects |