Heart implants have saved countless lives. People carrying one sometimes might fear 'What if the system fails?' Even worse: What if it's possible that someone wirelessly accesses the device to harm the patient?

It was a shocking episode of the successful US-series 'Homeland', when terrorists hacked their way into the heart implant of the nations' vice president and killed him by instructing it to shock his heart and induce cardiac arrest. What appeared to be science-fiction is not that far from reality. Former US vice president Dick Cheney reveals in his new book that he feared an assassination by terrorists and therefore ordered his doctors to disable the wi-fi function of his heart implant in 2007.

Actually, normal medical devices are not accessible from distances ranging more than a few meters. Cheney's doctor Jonathan Reiner describes the real threat: "It seemed to be a bad idea for the vice-president of the United States to have a device that maybe somebody in the next hotel room or downstairs might be able to hack into," he said during the CBS interview.

Cheney's revelation reflects concerns of researchers. For years they worry about the vulnerability of implanted medical devices since they're equipped with computerized functions and wireless capabilities. What was designed to allow the devices to be administered without additional surgery might also be a backdoor for criminals to maliciously control it. In June, the US Industrial Control Systems Cyber Emergency Response Team warned that some medical devices are vulnerable to potentially live-threatening hacks.

Securing implanted devices such as pacemakers or insulin pumps is a big challenge for researchers. They try to outsmart criminals by implementing security systems like using a patients  unique heart rate signature. The issue even found its way into the debates of this years security conference 'The Black Hat' in Las Vegas. Security Analyst Jay Radcliffe spoke about how vendors and buyers have to secure the devices.