doctors for medical examination for visa in k-w (水城百事)

My parents are applying the extension of their stay in Canada. Yesterday, we received a letter to require medical examinations. We are worried about that they may not pass the examinations due to the healthy condition of my mother( she had a heart attack before,and is still taking medications).There are several designated doctors in K-W. Anybody knows who is nicer and more friendly? We want find a nice doctor to make the examinations more smoothly.
Thanks