What is the physiological basis of clinical features of right ventricular (RV) failure?

From the Guidelines

Right ventricular failure occurs when the right ventricle cannot effectively pump blood to the lungs, leading to characteristic clinical features that stem from specific physiological mechanisms, primarily increased right ventricular pressure and volume overload, as noted in the 2018 American Heart Association scientific statement 1. The primary physiological basis involves increased right ventricular pressure and volume overload, which causes backward pressure transmission into the systemic venous circulation. This backward pressure results in:

• Peripheral edema, particularly in dependent areas like the ankles and sacrum, as fluid leaks from capillaries into interstitial spaces due to increased hydrostatic pressure
• Hepatomegaly and ascites develop as elevated central venous pressure is transmitted to the liver and portal circulation, causing hepatic congestion, impaired liver function, and fluid accumulation in the peritoneal cavity
• Jugular venous distention occurs as the elevated right atrial pressure is directly transmitted to the jugular veins Patients often experience:
• Fatigue and exercise intolerance due to reduced cardiac output, as the failing right ventricle cannot adequately fill the left ventricle, leading to decreased systemic perfusion
• Dyspnea results from pulmonary congestion in biventricular failure or from decreased left ventricular filling and output in isolated right ventricular failure
• Pleural effusions may develop from increased systemic venous pressure
• Palpitations from compensatory tachycardia as the heart attempts to maintain cardiac output despite reduced stroke volume These manifestations collectively reflect the heart's inability to maintain forward flow and the body's compensatory mechanisms attempting to preserve vital organ perfusion, as discussed in the 2018 American Thoracic Society research statement 1. The clinical features of right ventricular failure are associated with decreased exercise tolerance, poor functional capacity, decreased cardiac output, and progressive end-organ damage, as noted in the 2018 American Heart Association scientific statement 1. The assessment of right ventricular function is crucial in the evaluation and management of right-sided heart failure, and multiple hemodynamic and biochemical markers are associated with worsening right ventricular failure, as discussed in the 2018 American Heart Association scientific statement 1. Overall, the physiological basis of clinical features of right ventricular failure is complex and multifactorial, involving increased right ventricular pressure and volume overload, backward pressure transmission, and decreased cardiac output, leading to characteristic clinical manifestations, as noted in the 2018 American Thoracic Society research statement 1.

From the Research

Physiological Basis of Right Ventricular Failure

The physiological basis of clinical features of right ventricular (RV) failure can be understood by examining the factors that contribute to its development.

• Right ventricular failure is defined as the inability of the right ventricle to provide adequate blood flow through the pulmonary circulation at a normal central venous pressure 2.
• It is usually due to a combination of right ventricular pressure overload and contractile abnormalities of the right ventricular free wall 2.
• The right ventricle has a thin wall and is coupled to the pulmonary circulation, which is a low-pressure, low-resistance, high-compliance system 3.
• The RV compensates better for volume overload than for pressure overload and is more capable of sustaining chronic increases in load than acute ones 3.

Pathophysiology of Right Ventricular Failure

The pathophysiology of right ventricular failure involves an incapacity of the RV to adapt to an increase in afterload, which can become critical in acute pulmonary embolism and chronic pulmonary hypertension 4.

• Factors triggering RV failure in pulmonary hypertension, such as infection, pulmonary embolism, arrhythmias, or unplanned withdrawal of pulmonary arterial hypertension-targeted therapy, have to be considered and treated if identified 4.
• An impaired RV-pulmonary artery coupling leads to a major mismatch between RV function and arterial load ("afterload mismatch") and is associated progressively with a low cardiac output and a high right atrial pressure 3.
• Right ventricular dysfunction is involved in the pathophysiology of both cardiovascular and pulmonary diseases, and may partly explain the deleterious hemodynamic consequences of mechanical ventilation 3.

Clinical Features and Management

The clinical features of right ventricular failure include low cardiac output, high right atrial pressure, and signs of peripheral hypoperfusion 4, 5.

• Management of RV failure requires expertise and consists of optimization of fluid balance, cardiac output, perfusion pressure, and reduction of RV afterload with pulmonary arterial hypertension-targeted therapies 4.
• Inotropic support, such as dobutamine, and vasopressors, such as norepinephrine, may be used to support the right ventricle 4, 5.
• Extracorporeal life support, lung transplantation, or heart-lung transplantation should be considered in cases of refractory RV failure in eligible patients 4, 5.