Sinus rhythm: The normal regular rhythm of the heart set by the natural pacemaker of the heart called the sinoatrial (or sinus) node.
A medical assistant, as the name implies, is a professional who provides support to the doctors and medical staff by performing many of the clerical and administrative duties.
Medical assistants, sometimes called MAs, and certified nursing assistants, also called nursing aides or CNAs, both work with patients, but their job descriptions and educational tracks are quite different.