Heart Failure: Etiology, Classification, Stages, Pathophysiology, Pathology, and Complications

Heart failure (HF) is a complex clinical syndrome that results from structural or functional impairment of ventricular filling or ejection of blood. It is a leading cause of morbidity and mortality worldwide.

Etiology

Heart failure can be caused by various conditions, including ischemic heart disease, hypertension, cardiomyopathies, valvular heart disease, and arrhythmias.

Classification

• Heart Failure with Reduced Ejection Fraction (HFrEF) - EF <40%
• Heart Failure with Preserved Ejection Fraction (HFpEF) - EF >50%
• Heart Failure with Mid-Range Ejection Fraction (HFmrEF) - EF 40-50%

Stages of Heart Failure

• Stage A: At risk, no structural heart disease
• Stage B: Structural heart disease, no symptoms
• Stage C: Structural heart disease with symptoms
• Stage D: Refractory heart failure requiring specialized interventions

Pathophysiology

The pathophysiology of heart failure involves hemodynamic changes and neurohormonal activation.

Hemodynamic Changes

• Reduced cardiac output
• Increased systemic vascular resistance
• Fluid overload leading to pulmonary and systemic congestion

Neurohormonal Mechanisms

• Activation of the Renin-Angiotensin-Aldosterone System (RAAS)
• Increased sympathetic nervous system activity
• Increased release of vasopressin leading to fluid retention

Pathology

Histopathological findings in heart failure may include myocyte hypertrophy, fibrosis, interstitial edema, and cellular apoptosis.

Complications

• Acute decompensated heart failure
• Arrhythmias
• Thromboembolism
• End-organ dysfunction