VA (Venoarterial) ECMO (Extracorporeal Membrane Oxygenation) 

VA (Venoarterial) ECMO (Extracorporeal Membrane Oxygenation) is often indicated before heart transplant surgery in patients with end-stage heart failure. It serves as a life-supporting bridge to transplantation and facilitates the work of the heart. Below are the key considerations regarding the use of VA ECMO before heart transplant surgery.

Reasons for VA ECMO Pre-Transplantation

Support in cardiogenic shock – VA ECMO is indicated in patients with end-stage heart failure as a form of cardiogenic shock. This condition is characterized by an inability of the heart to pump sufficient amounts of blood leading to decreased perfusion of tissues and organs. VA ECMO helps to buy time for heart transplant surgery.

Bridge to transplantation – VA ECMO can be used as a bridge to heart transplantation. It allows for the creation of conditions for oxygenation and circulation independently of the heart and lungs. Such support is indicated, for instance, for patients with acute and severe forms of heart failure who are on the waiting list for heart transplantation.

Prevention of organ failure – with VA ECMO, sufficient amounts of oxygen are transported to the tissues and organs, thus preventing their dysfunction. This is especially important for the kidneys, liver, and the brain.

Critical patients – VA ECMO is indicated for critically ill patients who cannot undergo surgery or other therapeutic procedures. It is also indicated for patients with a very low chance of survival on the waiting list for a heart transplant. In these circumstances, VA ECMO is bridging patients to heart transplantation.

VA ECMO for Pre-Transplant Support: Mechanism

Venous cannulation – the blood is led from the venous system through a cannula placed in the right atrium or femoral vein (in case of femoral ECMO). Then, the blood is pumped through the circuit of VA ECMO.

Arterial cannulation – oxygenated blood is sent through another cannula into the arterial system, most often in the femoral artery or subclavian artery. Thus, VA ECMO provides the body with oxygen and facilitates circulation.

VA ECMO provides heart and lungs with the opportunity to rest. As for the work of the heart, VA ECMO takes over its function of circulation of blood throughout the body. As for the lungs, the work of oxygenation is performed by the membrane of the ECMO machine. Thanks to VA ECMO, oxygen saturation and tissue perfusion are ensured. In addition, the use of VA ECMO allows to prevent cardiac arrest and cardiogenic shock.

Indications for the Use of VA ECMO Before Transplantation

The main indication for the use of VA ECMO before heart transplant surgery is severe cardiogenic shock. It can be caused by different conditions, including end-stage heart failure, acute decompensated heart failure, cardiac arrest, etc.

Acute conditions – if a patient develops an acute reversible condition (for example, myocarditis or acute cardiac toxicity), he or she may need to be placed on VA ECMO as a bridge to recovery. In such cases, VA ECMO gives the heart a chance to recover, while the patient waits for a heart transplant.

High risk of mortality – patients are placed on VA ECMO, if their chances of surviving heart failure without surgery are low. In addition, VA ECMO is indicated if their condition has deteriorated to the point where they are now at risk of mortality on the waiting list for a heart transplant.

Ventricular assist devices (VAD) are another option for bridging patients to heart transplantation. However, if a patient is not a candidate for VAD, or if there is little time before transplant surgery, VA ECMO is a good alternative.

Benefits of VA ECMO Pre-Transplant

Hemodynamic stability – VA ECMO provides hemodynamic stability by temporarily taking over the work of the heart and lungs. Thus, it ensures tissue perfusion and oxygenation in patients whose heart is unable to perform the pumping function.

VA ECMO may be used as a bridge to recovery if a patient has acute reversible heart failure or other reversible conditions (such as myocarditis). However, if the function of the heart is not restored, VA ECMO will serve as a bridge to heart transplantation. If VA ECMO is used as a bridge to recovery, it allows to buy time for the heart to recover.

Improving the function of organs – by improving tissue perfusion, VA ECMO prevents kidney, liver, and brain dysfunction. This is extremely important, because acute organ failure during heart failure is a contraindication to heart transplantation. Thus, the use of VA ECMO before heart transplant surgery helps to reduce the risk of morbidity and mortality during the pre-transplant period.

VA ECMO is indicated as a bridge to heart transplantation in patients who are on the waiting list. Such patients are usually critically ill and their chances of surviving without a heart transplant are low.

Risks and Limitations of VA ECMO Pre-Transplant

Cannulation-related complications – complications associated with cannulation include bleeding, infection, vascular injuries, and thrombosis. Since VA ECMO requires the use of large catheters, the risk of bleeding is significant, in particular, central nervous system hemorrhage and gastrointestinal bleeding. In addition, the risk of infection is increased, especially with prolonged use of ECMO. Vascular injuries are also a common and dangerous complication; they can occur both at the site of cannulation and in other parts of the body.

Prolonged use of VA ECMO is associated with an increased risk of multi-organ failure or malfunction of the ECMO machine. Thus, prolonged use of VA ECMO is a risk factor for mortality during the pre-transplant period.

Other complications associated with VA ECMO include technical problems with the ECMO circuit. These problems are often associated with malfunction of the oxygenator or the pump. In such cases, clinicians need to quickly respond to the situation in order to avoid deterioration of the patient’s condition.

Prognosis

VA ECMO can save the lives of patients with severe heart failure and serve as an effective bridge to heart transplantation. The prognosis of patients who have recovered on VA ECMO largely depends on whether they can be discharged from it, as well as how long they use this method of extracorporeal life support. The sooner patients are weaned off VA ECMO, the lower the risk of developing serious complications. If the cause of heart failure is reversible, VA ECMO is used as a bridge to recovery.

A favorable prognosis also depends on the successful implementation of the heart transplant and the absence of post-transplantation complications. Thus, when used before heart transplant surgery, VA ECMO is an effective and relatively safe method of life support, which can buy time for the patient.