Current and Emerging Indications for Implantable Cardiac Monitors

Franco Giada, M.D.; Emanuele Bertaglia, M.D; Bernhard Reimers, M.D.; Donatella Noventa, M.D.; Antonio Raviele, M.D.

Disclosures

Pacing Clin Electrophysiol. 2012;35(9):1169-1178. 

In This Article

Limitations and Future Development of ICMs

Limitations

The subcutaneous implantation of ICMs is a minimally invasive procedure and may carry a risk of minor complications at the implantation site. In the literature, this complication is reported in less than 1% of the patients.[25]

Although several steps forward have been taken in the new-generations devices, one of the major limitations of ICMs still remain the sensing. Indeed, it is not uncommon to have a significant part of automatically detected events reflecting only artifacts. In order to try to overcome the oversensing problems, it is recommended to pay attention to the implanting technique (creating a tight subcutaneous pocket and anchoring the device to the muscular plane), and to periodically check, particularly in the first weeks following implantation, the autoactivation algorithms and the sensing parameters.

ICMs are one-lead ECG recorders and it is not always easy to distinguish between the various forms of supraventricular tachycardia, or between ventricular tachycardia and supraventricular tachycardia with aberrant conduction. Thus, an electrophysiological evaluation could be sometimes necessary in order to clarify the nature of recorded rhythm disorders. Moreover, another potential limit of ICMs, which has been partially overcome by the electrocardiographic classification of spontaneous syncope proposed by Brignole et al.,[13] is the difficulty in differentiating reflex bradyarrhythmias, which have a benign prognosis, from those related to intrinsic cardiac conduction disease, which have a poor prognosis. Finally, ICMs do not provide informations regarding blood pressure or EEG, potentially useful data for the study of patients with problematic syncope or transient lost of consciousness (TLOC).

Future Development

ICMs are equipped with electrodes for one-lead ECG detection. The same electrodes, alone or in combination with additional ones, could provide two or three-lead ECG recordings and consequently increase the reliability of rhythm interpretation. Moreover, they might also be used to measure other physiological signals, such as blood pressure, EEG, or subcutaneous impedance, that could be used in monitoring patients with TLOC and heart failure, respectively. In addition, ECG recordings might provide information not only on cardiac rhythm, but also on ischemia through the analysis of the ST segment, that could be useful in the management of patients with coronary heart disease and atypical symptoms or silent ischemia, such as diabetic subjects. Finally, miniaturization of the devices might promote their use by reducing their aesthetic impact and making the implantation procedure easier and faster.

We believe that the growing interest about ICMs, not only by the current companies, but also by the other manufacturers, will bring further interesting developments of these devices in the near future.

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