What are the causes of right-sided heart failure?

Causes of Right-Sided Heart Failure

Right-sided heart failure (RHF) has diverse etiologies that can be categorized into three main mechanisms: decreased RV contractility, RV volume overload, and RV pressure overload. 1

Classification of RHF Causes

1. Decreased RV Contractility

Acute Causes:

• Sepsis - leading to myocardial depression
• Right ventricular myocardial infarction (RVMI) - typically occurs with occlusion of a dominant right coronary artery proximal to major RV branches 1
• Myocarditis - inflammatory cardiac disease with RV involvement in up to 39% of cases with anti-heart autoantibodies 1
• Perioperative injury/ischemia (postcardiotomy) - following cardiac surgery
• Left ventricular assist device (LVAD) support - can lead to altered RV loading conditions

Chronic Causes:

• RV cardiomyopathy - primary disease of the right ventricle
• Arrhythmogenic right ventricular cardiomyopathy (ARVC) - genetic disorder affecting RV structure
• Ebstein anomaly - congenital malformation of the tricuspid valve

2. RV Volume Overload

Acute Causes:

• Excessive transfusion - leading to fluid overload

Chronic Causes:

• Left-sided valvular heart disease - causing backward pressure transmission
• Pulmonary regurgitation (PR) - often seen in repaired congenital heart disease
• Tricuspid regurgitation (TR) - primary or secondary valve dysfunction
• Single ventricle physiology - in congenital heart disease
• Transposition of the great arteries (TGA) - altered circulatory patterns
• Pericardial disease - affecting RV filling

3. RV Pressure Overload

Acute Causes:

• Pulmonary embolism (PE) - sudden obstruction of pulmonary circulation
• Acute respiratory distress syndrome (ARDS) - increased pulmonary vascular resistance
• Positive pressure ventilation - increasing RV afterload
• Acidosis - causing pulmonary vasoconstriction
• Hypoxia - triggering pulmonary vasoconstriction

Chronic Causes:

• Left-sided heart disease - most common cause of pulmonary hypertension
• Pulmonary arterial hypertension (PAH) - primary elevation of pulmonary pressures
• Chronic thromboembolic pulmonary hypertension - from unresolved pulmonary emboli
• Pulmonary stenosis (PS) - obstruction to RV outflow
• Restrictive cardiomyopathy - affecting both ventricles 1

Pathophysiological Mechanisms

Acute RHF

In acute RHF, the sudden increase in RV afterload or decrease in contractility leads to:

• Hemodynamic instability
• Decreased cardiac output
• Systemic hypoperfusion
• Venous congestion

This is the primary cause of death in massive pulmonary embolism, RV myocardial infarction, and postcardiotomy shock. 1, 2

Chronic RHF

Chronic RHF develops progressively and is characterized by:

• Decreased exercise tolerance
• Poor functional capacity
• Progressive end-organ damage from venous congestion and underperfusion
• Cachexia from poor nutrient absorption and proinflammatory state 1, 3

Clinical Significance and Prognosis

RV dysfunction is associated with poor outcomes across multiple conditions:

• In heart failure with preserved ejection fraction (HFpEF), RV dysfunction is associated with ~45% two-year mortality compared to 7% without RV dysfunction 1
• In myocarditis, RV dysfunction carries a hazard ratio of 3.4 for death or heart transplantation 1
• In pulmonary arterial hypertension, RHF is the principal cause of death 1

Special Considerations

Ventricular Interdependence

• RV failure affects left ventricular filling through septal displacement
• This leads to decreased left ventricular stroke volume and can progress to cardiogenic shock 2

RV-PA Uncoupling

• In advanced RHF, the RV becomes uncoupled from the pulmonary circulation
• This represents a critical point in disease progression where compensatory mechanisms fail 4

Common Pitfalls in Diagnosis and Management

1. Overlooking RV dysfunction in patients with left-sided heart failure
2. Failing to identify the underlying cause of RHF, which is crucial for targeted therapy
3. Inappropriate fluid management - excessive fluid can worsen RV failure, while inadequate fluid may reduce preload
4. Neglecting ventricular interdependence when treating isolated left or right heart failure

Early recognition of RHF and identification of underlying etiology are essential for effective treatment and improving prognosis. The management approach should be tailored to the specific mechanism causing RHF, whether it's decreasing RV afterload, optimizing preload, or improving contractility. 3