132. Heart failure - etiology, classification, compensatory mechanisms, clinical manifestations.

Heart failure

Definition

Heart failure (HF) is a clinical syndrome in which the heart is unable to pump sufficient blood to meet the metabolic needs of tissues, or can do so only at elevated filling pressures.

Etiology

1. 1 Myocardial causes

• Ischemic heart disease (most common cause in developed countries).
• Myocarditis.
• Cardiomyopathies (dilated, hypertrophic, restrictive).

1. 2 Pressure overload (afterload increase)

• Hypertension.
• Aortic stenosis.

1. 3 Volume overload (preload increase)

• Valvular regurgitation (mitral, aortic).
• Renal failure (fluid retention).

1. 4 Arrhythmias

• Persistent tachyarrhythmias (e.g., atrial fibrillation with rapid ventricular response).
• Bradyarrhythmias (e.g., advanced AV block).

Classification

By side of heart

By output

By time course

Compensatory mechanisms

1. 1 Frank- Starling mechanism

• Increased preload → increased stretch → stronger contraction (limited in advanced HF).

1. 2 Neurohormonal activation

• Sympathetic nervous system → ↑ heart rate, contractility, vasoconstriction.
• Renin-angiotensin-aldosterone system (RAAS) → sodium and water retention → increased blood volume.
• Antidiuretic hormone (ADH) → water retention → increased blood volume.

1. 3 Myocardial remodeling

• Hypertrophy of cardiac muscle to compensate for increased workload.
• Initially adaptive but ultimately maladaptive → fibrosis, reduced compliance.

Clinical manifestations

Left- sided heart failure

• Pulmonary congestion symptoms:
• Dyspnea on exertion → orthopnea → paroxysmal nocturnal dyspnea.
• Cough with pink frothy sputum (pulmonary edema ).
• Basal lung crackles.
• Reduced systemic perfusion:
• Fatigue, weakness.
• Renal hypoperfusion → oliguria.

Right- sided heart failure

• Systemic venous congestion symptoms:
• Peripheral pitting edema.
• Hepatomegaly → congestive hepatopathy, "nutmeg liver".
• Ascites.
• Jugular venous distension (JVD).
• Anorexia, nausea (gut congestion).

General symptoms (any HF)

• Exercise intolerance.
• Tachycardia.
• Weight gain (fluid retention).

Summary table

Conclusion

Heart failure results from inadequate cardiac output or congestion, with compensatory mechanisms that may initially help but eventually worsen the condition. Clinical features depend on side and type of dysfunction.

Let me know if you'd also like a flowchart summarizing compensatory mechanisms, or "left vs right HF comparison" diagrams!

Here’s a complete, clear, and detailed note on acute heart failure, including classification, etiology, pathogenesis, and clinical manifestations — fully academic but easier to understand and memorize.