What are the effects of Veno-Arterial (VA) Extracorporeal Membrane Oxygenation (ECMO) on right heart function?

Effects of VA ECMO on Right Heart Function

VA ECMO has dual effects on right heart function, potentially unloading the right ventricle by reducing preload while simultaneously increasing afterload, which requires careful hemodynamic monitoring and management to optimize outcomes. 1

Physiological Impact of VA ECMO on Right Heart Function

Beneficial Effects

• Preload Reduction: VA ECMO drains blood from the venous system, decreasing right ventricular (RV) filling pressures and volume 2
• Improved Oxygenation: By increasing blood oxygenation, VA ECMO can help limit pulmonary artery hypertension, thereby unloading the right ventricle 2
• Hemodynamic Stability: Provides circulatory support in cases of cardiogenic shock with very low cardiac output 2

Detrimental Effects

• Increased Afterload: The arterial return of VA ECMO can increase systemic vascular resistance, which may indirectly affect RV function 2
• Potential for RV Distention: If improperly managed, VA ECMO can lead to left ventricular distention which may affect interventricular dependence and RV function 1
• Risk of Thrombotic Complications: Despite anticoagulation, thrombotic and thromboembolic complications are common with VA ECMO and can affect RV function 2

Hemodynamic Monitoring During VA ECMO

Proper monitoring is essential to assess RV function during VA ECMO:

• Echocardiography: Repeated echocardiographic assessment is crucial for evaluating RV size, function, and interventricular dependence 2, 1
• Continuous Monitoring: Arterial blood pressure, ECMO flow, and extracorporeal blood flow require continuous monitoring 2
• Laboratory Parameters: Daily fluid balance, SvO₂, and lactate levels should be monitored 2, 1
• Avoid Thermodilution Methods: Continuous thermodilution-based and pulse contour analysis-based cardiac output monitoring are not recommended as they may lead to erroneous results due to indicator loss into the extracorporeal circuit 2

Optimizing RV Function During VA ECMO

Flow Management

• Higher ECMO blood flow rates resulting in higher SvO₂ (>80%) decrease pulmonary artery pressure, cardiac output, and right heart workload 3
• Careful titration of flow is necessary to balance systemic perfusion needs with RV unloading

Fluid Management

• Careful Volume Control: Accurate recording of fluid intake and output is important as positive fluid balance has been identified as an independent predictor of outcomes 2
• Avoid Hypovolemia: May induce venous collapse during extracorporeal blood extraction, causing cannula "suctioning" 2
• Prevent Volume Overload: Can aggravate lung edema and worsen RV function 2

Special Considerations

Right Heart Failure After Heart Transplantation

• VA ECMO has shown better results than right ventricular assist devices or retransplantation for transient right heart failure after heart transplantation 4
• Early application of VA ECMO for RHF after heart transplantation has been reported as a good option 4

Alternative Configurations for RV Support

• In cases of isolated RV failure, a right ventricular assist device with an oxygenator (Oxy-RVAD) using ECMO may be considered, with drainage from the femoral vein and return to the pulmonary artery 5
• Peripheral VA ECMO can be used as short-term treatment for right heart failure after left ventricular assist device implantation 6

Potential Complications Affecting RV Function

• Bleeding: Most frequent complication that can lead to hemodynamic instability affecting RV function 1
• Thrombosis: Despite anticoagulation, thrombotic events can occur and affect pulmonary circulation 2, 1
• Hemolysis: More common in VA ECMO than VV ECMO and can contribute to kidney injury 1

Clinical Decision-Making

When considering VA ECMO for patients with right heart dysfunction:

1. Evaluate Underlying Cause: Determine if RV dysfunction is primary or secondary to left heart failure
2. Assess Severity: Use echocardiography to evaluate RV size, function, and pulmonary pressures
3. Consider Timing: Early implementation may be more beneficial than rescue therapy 2
4. Multidisciplinary Approach: Decision should involve PAH specialists, cardiothoracic surgeons, and ECMO specialists 2
5. Bridge Strategy: Determine if VA ECMO is being used as bridge to recovery or bridge to transplantation, as this affects management 2

VA ECMO remains a complex intervention requiring specialized knowledge and careful monitoring to optimize its effects on right heart function while minimizing complications.