"Tianjiu 2", "Tianjiu 3" and "Tianjiu 4", clad in traditional Chinese garments, are seen in this picture to wish happy Chinese New Year. [For chinadaily.com.cn]

A ventricular assist device (VAD) implanted in a group of sheep has been working well and the next step is clinical tests, Chinese researchers said.

Co-developed by the No. 18 Institute of China Academy of Launch Vehicle Technology and Tianjin's TEDA International Cardiovascular Hospital, the third-generation VAD, known as "Rocket Heart", was launched in 2009.

It went into animal testing at the end of last year and no signs of abnormality have been reported.

Chronic heart failure has become one of the most common and life-threatening cardiovascular diseases. There are approximately 80 million patients globally of which 16 million are in China.

Lack of donor hearts is responsible for a long waiting list of patients requiring transplants. The United States spent 30 billion US dollars on sufferers in 2012 and it is predicted expenditure will increase to 43 billion US dollars in 2020 and 69 billion by 2030.

On March 14, 2013, a sheep named "Tanjiu 1" was successfully implanted with the third-generation VAD. All post-operative indexes remained normal and by surviving for 120 days the animal created a new record for the third-generation VAD.

The research team made several modifications last year and since Dec 23 pumps have been implanted in "Tianjiu 2", "Tianjiu 3" and "Tianjiu 4". To date, all the three sheep remain very healthy.