Basic Properties And Clinical Applications Of The Intracardiac

Abstract

signals.2-4 However, the morphological evaluation of ventricular waveforms can add further insight, and is feasible even with a singlechamber stimulator. To this purpose, the electrogram filter bandwidth must be enlarged and the sensitivity to remote phenomena increased, at the expense of specificity. Normally, the electrograms used by the sensing algorithms are high-pass filtered, while those recorded for diagnostic applications include lower frequency components. Some ICDs offer in addition the possibility to record "far-field electrograms" between the defibrillation coil and the stimulator can, besides the standard "near-field signals" derived by the pacing electrodes, in the aim to better recognize wide and narrow QRS complexes, which in turn would orient the diagnosis toward a VT or SVT, respectively 5,6 . An alternative approach to far-field sensing, which can be accomplished in pacemakers and. ICDs as well, has recently been developed and referred to as intracardiac ECG (iECG) [7][8][9][10] . The iECG tracing closely resembles a surface ECG lead, featuring striking different waveforms in case of physiological AV conduction along the His-Purkinje pathway, left or right bundle branch block (LBBB, RBBB), idioventricular rhythm or ectopic ventricular beats (PVC). If the ventricle is paced, the ventricular component of the iECG depends on the stimulation target, which can therefore be identified. In the event of a tachycardia, the iECG allows reliable discrimination of VTs and SVTs, providing in addition detailed information on pre-excitation and retrograde AV conduction 7,8. The main properties of the iECG and its actual and potential applications in the clinical setting are reviewed in the present paper.www.jafib.com AbstractThe electric signals detected by intracardiac electrodes provide information on the occurrence and timing of myocardial depolarization, but are not generally helpful to characterize the nature and origin of the sensed event. A novel recording technique referred to as intracardiac ECG (iECG) has overcome this limitation. The iECG is a multipolar signal, which combines the input from both atrial and ventricular electrodes of a dual-chamber pacing system in order to assess the global electric activity of the heart. The tracing resembles a surface ECG lead, featuring P, QRS and T waves. The time-course of the waveform representing ventricular depolarization (iQRS) does correspond to the timecourse of the surface QRS with any ventricular activation modality. Morphological variants of the iQRS waveform are specifically associated with each activity pattern, which can therefore be diagnosed by evaluation of the iECG tracing. In the event of tachycardia, SVTs with narrow QRS can be distinguished from other arrhythmia forms based upon the preservation of the same iQRS waveform recorded in sinus rhythm. In ventricular capture surveillance, real pacing failure can be reliably discriminated from fusion beats by the analysis of the area delimited by the iQRS signal. Assessing the iQRS waveform cor...

Non-invasive method for blood glucose monitoring using ECG signal

“…49, 50 Surface ECG lead and intracardiac signal properties are suited for morphological characterization. 49 However, the acquisition of intracardiac signals involves the application of additional bioelectric sources along with invasive catheter-based approaches 50 reducing its availability. On the contrary, as previously mentioned, ECG device is non-invasive, simple to implement, and widely available on the market with a diverse variety of processing methods.…”