FORT WORTH, Texas--(BUSINESS WIRE)--MedStar EMS, the 911 provider of Fort Worth, and 14 surrounding cities, has outfitted its fleet of emergency vehicles with Philips HeartStart MRx Monitor/Defibrillators with Q-CPR technology, to enhance care for patients with cardiac emergencies. The Philips HeartStart MRx is a monitor/defibrillator with specialized features and capabilities designed to meet the technical and environmental demands of emergency responders. The HeartStart MRx provides advanced functionality and features the longest battery-powered operating time, as well as the largest color display and fastest time to shock of any monitor/defibrillator.