Professor Ping Li "Extra-VAD, could be a greater life-support solution for Bridging to Heart Transplantation"

On July 24, 2021, sponsored by the Chinese Medical Doctor Association and the Professional Committee of Chinese Society of ExtraCorporeal Life support (CSECLS), undertaken by ZhongDa Hospital SouthEast University, Beijing Anzhen Hospital, Capital Medical University, and co-organised by the Chinese Society of Extracorporeal Circulation and Jiangsu Medical Doctor Association, the 5th Chinese Society of ExtraCorporeal Life Support Annual Meeting (CSECLS 2021) was grandly held online.

This conference invited Prof. Li from the Cardiovascular Surgery Department of the Union Hospital, Tongji Medical College, Huazhong University of Science and Technology  (hereinafter referred to as: Wuhan Union Hospital). Prof. Li shared about the value, advantages, and disadvantages of ECMO and the extracorporeal ventricular assist device as a bridging heart transplantation at the online meeting.

Prof. Li said that heart failure is a cardiovascular disease that has been on the rise for nearly 70 years worldwide. Heart transplantation is the gold standard for the treatment of end-stage heart failure, but the shortage of donor hearts makes many end-stage heart failure patients need effective treatment before heart transplantation. For patients with end-stage heart failure, drug therapy has little effect, during this period, mechanical circulatory support (MCS) is necessary to help patients.

MCS can maintain hemodynamic stability, reduce drug dose, ensure effective organ perfusion, improve cardiac function, and reduce cardiac load.

Depending on the duration of the assistance, MCS is divided into:

·  Temporary Mechanical Circulatory Support (Temporary MCS): IABP, Impella, ECMO, Extra-VAD

•  Long Lasting Mechanical Circulatory Support (Persistent MCS): Implant VAD

Temporary MCS (above) and Persistent MCS (below)

China's existing cardiac mechanical circulatory support methods:

•  ECMO assistance: rapidly developing, but currently monopolized by imported products (bottleneck)

•  Ventricular assist device: widely used in other countries, but it is still in its infancy in China. 

ECMO's significance and Values

Bridging advantages of ECMO as a circulatory assist technology:

•  Can be used as pre-transplant support, for transitioning

•  Can be used as post-transplant PGD support

•  Can provide bi-cardiac support and respiratory support

ECMO circulatory support has the advantages of dual cardiopulmonary support, large span, and multiple conversions, which can effectively help patients safely pass through the dangerous period and stabilize the condition of patients with heart failure; aids in reversible cardiac recovery to provide time for the perioperative period of heart transplantation in patients with end stage heart failure, which is usually 3-5 days.

As a kind of temporary mechanical circulatory support, ECMO is of great significance and value in bridging heart transplantation and has become a trend. The latest organ allocation system makes VA-ECMO bridge the highest priority on the waiting list for heart transplantation, which helps to reduce mortality on transplant waiting lists.

Is ECMO the optimal solution?

ECMO plays a crucial role in bridging heart transplantation, but it needs to be evaluated for safety and efficacy in clinical use. The high negative pressure at the inlet end of the ECMO system and the membrane oxygenator attached to the thrombus can cause haemolysis, which will reduce the oxygen-carrying capacity of red blood cells and damage the renal tubules. Therefore, monitoring the free hemoglobin content in a timely and effective manner is necessary.

According to data from the United Network for Organ Sharing: From 2013 to 2016, a total of 25,168 adult heart transplants were performed, of which only 107 were bridged by ECMO, accounting for 0.4%, while 6,148 were bridged by continuous flow left ventricular assist device (LVAD)., accounting for 24.4%. Heart transplantation via ECMO bridging is extremely rare, and from the data results seen, the early/mid-term mortality of ECMO bridge heart transplant patients is also higher.

ECMO bridging heart transplantation may lead to poor early and mid-term post-transplant survival, increasing post-transplant mortality, and cause organ waste. Therefore, whether ECMO is the optimal solution for bridging heart transplantation should be further discussed.

Ventricular Assist Device (VAD)

Becomes an important surgical treatment method for heart failure

Due to the shortage of donor hearts, artificial hearts (ventricular assist devices, abbreviated VAD) have become a research topic. Since 2006, nearly 30,000 patients worldwide have received VAD treatment. The relevant clinical research data in the United States show that whether it is the first, second or third generation Artificial heart, compared to drugs, it can significantly improve the survival rate of patients with end-stage heart failure. VAD has become an important means of surgical treatment for heart failure and the extracorporeal ventricular assist device (Extra-VAD) may be a better option than ECMO in bridging heart transplantation.

Compared to ECMO, Extra-VAD has greater advantages

•  It doesn't use the membrane lung, which eliminates the complications and complications associated with lung.

•  The central intubation method also avoids the problem of distal limb ischemia.

•  There is no ECMO reverse blood flow problem, which can completely unload the ventricle without drainage, which is more powerful for cardiac recovery.

•  Survival of bridging heart transplantation is higher than ECMO.

•  Significantly less damage to blood.

•  The nursing team only needs 1~2 people.

Therefore, Extra-VAD may be a better choice for short-term bridging heart transplant patients.

Led by Wuhan Union Medical College Hospital, R&D collaboration with magAssist 

Extracorporeal Ventricular Assist Device

The Extra-VAD jointly developed by Wuhan Union Hospital and magAssist is a complete magnetic levitation blood pump used for short and mid-term extracorporeal ventricular assist. It is the only extracorporeal ventricular assist device in China with completely independent intellectual property rights and has multiple ventricular assist modes available. 

Clinical translation

First successful bridging heart transplant (BTR) case

First successful bridging heart transplant patient 

A 31-year-old female patient was diagnosed with end-stage heart failure, with severe symptoms of heart failure, low blood pressure, and unstable circulation. Because the patient has type O blood, the waiting time for the heart transplantation is longer, and it is difficult to maintain conventional medical treatment. After discussion in the general department of Wuhan Union Hospital, it was decided to perform support therapy with Extra-VAD to help the patient stabilize circulation. After 296 hours and 38 minutes (over 12 days) of stable circulatory assistance, the patient successfully received a heart transplant surgery, the patient's trachea was pulled out 10 hours after the operation, and she could sit up and eat on her own 3 days after the operation and could get out of bed and stand 5 days post-surgery, the overall recovery state was excellent.

Extracorporeal Ventricular Assist Device

Better option for bridging heart transplantation

In general, ECMO-assisted bridging heart transplantation has many complications, more blood transfusions, more rejections, and high mortality rates. Patients with end-stage heart failure or when ECMO-assisted bridging heart transplantation is relatively stable can choose to transition to ventricular assist device bridging heart transplantation. Short and mid-term Extra-VAD, has fewer complications, easy management, and lower price, may be a more optimal solution for bridging heart transplantation.