## 5 Remote Monitoring Technologies  
Electronics systems used for diagnostics, e.g., endoscopic capsule, remain within the body of the patient only a short time, and the patient is typically monitored by the physician at the clinic for the duration of the procedure. Implantable electronics systems that are intended to reside within the body of the patient for years, e.g., implantable cardiovascular devices, are reviewed intermittently, with follow-up visits followed by extended periods of time when the medical practitioner receives no information regarding the performance of the implantable system or the well-being of the patient. The operating parameters of the indwelling device also remain static between the follow-up visits, which may not reflect the needs and the clinical state of the patient. Then again, many scheduled follow-up visits do not result in any changes being made to the device parameters and the patient requires no medical intervention. A retrospective analysis of 1739 clinical visits by a random set of 169 patients with implantable cardiovascular devices found that out of 1530 scheduled visits, 1197 visits resulted in no relevant medical or device-related findings [106]. The non-scheduled visits, on the other hand, were significantly more likely to result in identification of device- and/or patient-related problems and require medical treatment, device re-programming, and hospitalization. Remote monitoring can provide a robust system capable of timely capturing the device- or patient-related issues, and ensuring that healthcare time and resources are spent where they are most required [5]. Indeed, the same retrospective study found that a remote monitoring system was capable of correctly detecting the vast majority of arrhythmias and/or device-related problems, potentially missing an isolated pacing problem in less than 0.5% of all patients investigated [106]. Similarly, a study involving the comparison between clinical traditional observation and remote measurements found no statistical difference between the two conditions [107]. Remote monitoring involves a periodic transfer of data, e.g., device parameters and functions, biological signals and clinical status of the patient, from the indwelling module to a transmitter which is typically located outside of but in a close proximity to the body [108]. There are a number of biological parameters that are monitored depending on the patient, their medical condition and the type of indwelling device. For instance, in those suffering from heart failure, common parameters to measure include: transthoracic impedance to detect changes in fluid balance; electrocardiogram to identify the onset of atrial or ventricular arrhythmias; blood pressure to manage hyper- or hypotension using adequate administration of medicines, e.g., angiotensin-converting enzyme inhibitors and beta-blockers; temperature as an indicator of potential infection; and blood oxygen saturation levels [20,109]. Upon receipt of the data by the transmitter, the information is encrypted and securely sent to a central server of the manufacturer of the implantable system trans-telephonically or via web-based networks [37]. For example, Home Monitoring technology introduced by Biotronik (Biotronik GmbH, Berlin, Germany) in 2001 uses a device similar to a mobile phone to automatically transmit encrypted information from implanted electronic cardiovascular devices, e.g., pacemakers, implantable cardioverter-defibrillators, and heart failure devices, to a central server using mobile phone network. Other systems that use standard and mobile telephonic communication channels include CareLink developed by Medtronic (Medtronic Inc., Minneapolis, MN, USA), Housecall Plus used by St. Jude Medical (St. Jude Medical, Sylmar, CA, USA), and Latitude by Boston Scientific/Guidant (Boston Scientific, St. Paul, MN, USA) [110]. Currently available remote monitoring systems are manufacturer-specific, that is they can only be employed to interrogate devices fabricated by the same manufacturer [108].