Gregg Stone visits the Nanjing No 1 Hospital in December. He says he's surprised by the advances of China's healthcare industry over a short period of time. [Photo provided to China Daily]

Over the years, such collaborations have expanded to hospitals in Beijing, Nanjing, Shenzhen and other cities. Stone is also involved in promoting China's medical progress in the world.

After Chinese doctor Chen Shaoliang and his team from Nanjing No 1 Hospital developed a technique called the "DK Crush", which is said to significantly enhance the quality of treatment for a disease in the coronary artery, Stone actively helped them to promote the method internationally.

The technique was displayed at two important international medical conferences, including the 2011 Transcatheter Cardiovascular Therapeutics, which helped it gain wider recognition.

Stone is also helping Chen do international collaborative research to prove that a separate method developed by Chen to treat pulmonary hypertension is effective, before it can be adopted worldwide.

According to Chen, Stone has helped the Nanjing hospital in Jiangsu province, develop its cardiovascular medicine department further.

Besides coming to China for research, meetings and to train doctors almost every year－sometimes at his own cost-Stone has also accepted several cardiologists from the hospital for training at his hospital in the US.

"He is very patient while answering questions from Chinese doctors," says Chen. "As a foreign expert, he has served selflessly...we value his work very much."

In 2015, the Nanjing No 1 Hospital and New York-Presbyterian Hospital jointly established a research institute on heart diseases in Nanjing. The ground work included a series of collaborative plans.