Venoarterial ECMO

VA-ECMO is a form of extracorporeal life support where blood is withdrawn from the venous system and then infused into the arterial system to provide partial or complete circulatory or cardiac support; respiratory support by VA-ECMO can be adequate or suboptimal depending on the circumstances.

  • Configurations
    • the most common configuration is to use femoral venous cannulation and advance the cannula into or near the right atrium to drain blood and pump it through a membrane oxygenator for oxygenation and decarboxylation
    • can also be configured using central intrathoracic cannulation in which the right atrium or pulmonary artery is cannulated directly for venous drainage and the innominate artery, left atrium, aorta, or left ventricle are directly cannulated for arterial reinfusion
  • blood is then returned to a femoral artery where it flows retrograde up the aorta
  • percutaneous ultrasound-guided cannulation is preferred, rather than the surgical approach, to decrease complications
  • additional distal perfusion catheter is often inserted into the superficial femoral artery to minimise limb ischaemia, distal to the cannula
  • ECMO from the right atrium to the pulmonary artery with two cannulae or with a dual-lumen cannula, percutaneously inserted through the jugular vein (PROTEK Duo; LivaNova), can support the right ventricle and provide gas exchange if required
  • VA-ECMO affects haemodynamics and gas exchange in a complex way
    • provides retrograde aortic flow which increases LV afterload and can result in increased LV end-diastolic pressure, aortic and mitral regurgitation, a decrease in coronary artery blood flow, and possibly severe pulmonary oedema
    • retrograde ECMO flow might also decrease or prevent LV ejection, leading to stasis and thrombosis within the cardiac chambers
    • strategies to reduce LV afterload, promote LV ejection, and directly vent the LV are
      • Decrease pump flow to reduce LV afterload, lower ECMO blood flows might prevent severe LV dilation
      • Inotropes to promote LV ejection
      • IABP, decreases LV pressures and pulmonary oedema
        • In a meta-analysis including 17 retrospective observational registries with 3997 patients, the use of an IABP with VA-ECMO was associated with fewer deaths (54% vs without 65%, risk ratio 0.79; 95% CI 0.72–0.87; p<0·00001) compared with VA-ECMO alone
      • Impella, decreases in pulmonary capillary wedge pressure
      • Atrial septostomy
      • Apical cannula directed to the ECMO draining line