Medical devices classified as high risk typically include implants, life-supporting equipment, and devices intended for critical medical procedures. Can you provide examples of high-risk medical devices, such as implantable cardioverter-defibrillators (ICDs), ventilators, and surgical implants? How does regulatory oversight, such as the FDA's premarket approval (PMA) process, ensure the safety and effectiveness of these devices before they enter the market? Furthermore, what measures are in place to monitor and address potential risks associated with the use of high-risk medical devices in clinical practice?