The Use of Venoarterial Extra-Corporeal Membrane Oxygenation for Mechanical Circulatory Support of Heart Patients

Venoarterial Extra-Corporeal Membrane Oxygenation, or VA-ECMO, is a life support treatment used for patients who have severe and life-threatening heart problems. The ECMO device can replace the functions of both the heart and lungs and support patients from a few hours to multiple days, depending on their condition and progress.

Through plastic tubes placed in large veins and arteries in the body, the ECMO equipment pumps blood from the patient's body to an artificial lung (oxygenator), which adds oxygen and removes carbon dioxide. The ECMO machine warms the oxygen-filled blood before returning it to the patient’s artery via a pump with the same force as the heart, replacing its function. The process uses a hemofilter that acts as an artificial kidney, and heparin to prevent blood from clotting while outside the body.  The treatment allows the heart and lungs to rest and heal.

ECMO therapy has been around since the 1970s. Its use has continually increased as a supportive treatment for cardiac, respiratory and combined cardiopulmonary failure. ECMO procedures gained significant publicity during the pandemic related to respiratory use with COVID-19 patients. But from a cardiovascular perspective in our heart hospital, our most frequent use of ECMO tends to be with patients experiencing cardiogenic shock.

In its simplest form, ECMO is a miniaturized heart-lung machine. It can function as an artificial heart or artificial lung. The equipment is relatively small and easy to transport, so a two-person ECMO transport team can take the treatment to a remote patient at a hospital without ECMO capability and stabilize the patient for transport back to a major medical center for specialized care. Because of the technology and skill required to use ECMO, only a few hundred hospitals nationwide currently have the ability to perform ECMO,including Medical City Heart Hospital, Medical City Children’s Hospital and Medical City Plano, which have survival rates 18 percent -30 percent better than ELSO national ECMO registry outcomes.

A recent example of the successful use of VA-ECMO demonstrates the difference this therapy can make with cardiac patients. The Medical City Heart Hospital ECMO transport team, consisting of Brian Lima, MD, surgical director of heart transplantation and mechanical circulatory support, and ECMO Coordinator Omar Hernandez, RN, traveled recently to a nearby hospital to initiate ECMO therapy for a patient who had undergone emergency triple-bypass surgery. The patient, Leo, was in post-cardiotomy shock (PCS) and not responding to treatment. PCS occurs in 3 percent -5 percent  of cardiac operations and is associated with substantial morbidity and mortality, according to a 2021 article in Anesthesiology. magazine.  PCS is characterized by heart failure that occurs immediately postoperatively or when patients cannot wean off cardiopulmonary bypass. These situations provide the most common indications for mechanical circulatory support such as ECMO, according to an article in General Thoracic And Cardiovascular Surgery

When VA-ECMO is used in cardiogenic cases, there is typically an instant response. The patient’s blood pressure will rise immediately, which is what happened with Leo.  With his organs stabilized, Leo was transferred to Medical City Heart Hospital for a successful heart transplant.

In the hospital, ECMO requires two staff specialists at the patient’s bedside 24/7, as well as a team of surgeons, perfusionists, ECMO nurse specialists, cardiologists, neuro-radiologists, respiratory care practitioners and numerous other staff who provide support along a patient's journey of care.

Although ECMO itself will notcure or treat the disease that led to heart or lung failure, it is a life-sustaining treatment that can allow more time to fix the problem. It also gives the patient’s organs time to rest and recover. In Leo’s case, ECMO helped stabilize him so that a heart transplant could be performed.