Heart Failure: Left vs. Right-Sided

Heart Failure: Left vs. Right-Sided

• Heart failure (HF) occurs when the heart cannot pump enough blood forward (decreased cardiac output).

• Can affect left, right, or both sides (biventricular failure).

• One-sided failure can eventually lead to the other side failing:

  • Most common: Left → Right

  • Less common: Right → Left

• Symptoms arise from:

  1. Forward failure: insufficient blood delivered to organs.

  2. Backward failure: blood backs up into systemic or pulmonary circulation.

Left-Sided Heart Failure (LSHF)

Function affected

• Left ventricle fails to pump oxygenated blood to the body.

• Blood backs up into pulmonary circulation.

Common causes

• Chronic conditions:

  • Coronary artery disease (CAD)

  • Cardiomyopathies

  • Valvular diseases (Aortic stenosis, Mitral regurgitation)

• Acute causes:

  • Acute MI

  • Acute valvular failure

  • Drug toxicity (e.g., cocaine)

Pathophysiology

• Backup of blood → increased pulmonary artery pressure

• Fluid shifts into lungs → pulmonary edema (congestive heart failure)

• Decreased forward flow → decreased perfusion to organs

Signs & Symptoms

Due to pulmonary congestion (backward failure):

• Pulmonary edema → crackles/rales on auscultation

• Dyspnea, orthopnea (difficulty breathing lying down)

• Pink, frothy sputum

Due to decreased forward flow:

• Fatigue, weakness, lethargy

• Decreased urine output (fluid retention)

• Rapid or irregular heartbeat (compensatory tachycardia)

Right-Sided Heart Failure (RSHF)

Function affected

• Right ventricle fails to pump blood to the lungs.

• Blood backs up into systemic circulation.

Common causes

• Most common: Left-sided heart failure → chronic increased pulmonary pressure → right ventricle overload

• Isolated causes:

  • Left-to-right shunts (ASD, VSD)

  • Chronic lung disease (cor pulmonale)

Pathophysiology

• Blood backup → increased central venous pressure (CVP)

• Fluid shifts → peripheral edema

• Decreased forward flow → decreased oxygenation and perfusion

Signs & Symptoms

Due to systemic congestion (backward failure):

• Jugular venous distention (JVD)

• Peripheral edema (feet, legs, sacrum)

• Pitting edema in severe cases

• Hepatosplenomegaly → possible liver dysfunction/cirrhosis

• Ascites

• Weight gain from fluid retention

Due to decreased forward flow:

• Fatigue, weakness, lethargy

• Rapid or irregular heartbeat

• Increased nocturnal urine output (fluid reabsorption when lying down)

Key Differences: Left vs Right HF

Feature	Left-Sided HF	Right-Sided HF
Blood backup	Pulmonary circulation	Systemic circulation
Major symptoms	Pulmonary edema, dyspnea, orthopnea, pink frothy sputum	Peripheral edema, JVD, hepatosplenomegaly, ascites, weight gain
Urine output	Decreased (fluid retention)	May increase at night (nocturia)
Causes	CAD, cardiomyopathy, valvular disease (left-sided)	Left HF, lung disease, shunts

Biventricular (Both Sides) Failure

• Combination of left and right-sided signs

• Often develops after chronic left-sided HF

• Systolic vs diastolic dysfunction: Both can lead to left or right-sided HF.

• Symptoms depend on the side affected and whether failure is forward (reduced perfusion) or backward (fluid backup).

• Acute vs chronic HF: Acute events may be reversible; chronic conditions cause long-term HF.