[Analysis of pacemaker ECGs].
BACKGROUND
The key to a successful analysis of a pacemaker electrocardiogram (ECG) is the application of the systematic approach used for any other ECG without a pacemaker: analysis of (1) basic rhythm and rate, (2) QRS axis, (3) PQ, QRS and QT intervals, (4) morphology of P waves, QRS, ST segments and T(U) waves and (5) the presence of arrhythmias.


METHODS
If only the most obvious abnormality of a pacemaker ECG is considered, wrong conclusions can easily be drawn. If a systematic approach is skipped it may be overlooked that e.g. atrial pacing is ineffective, the left ventricle is paced instead of the right ventricle, pacing competes with intrinsic conduction or that the atrioventricular (AV) conduction time is programmed too long. Apart from this analysis, a pacemaker ECG which is not clear should be checked for the presence of arrhythmias (e.g. atrial fibrillation, atrial flutter, junctional escape rhythm and endless loop tachycardia), pacemaker malfunction (e.g. atrial or ventricular undersensing or oversensing, atrial or ventricular loss of capture) and activity of specific pacing algorithms, such as automatic mode switching, rate adaptation, AV delay modifying algorithms, reaction to premature ventricular contractions (PVC), safety window pacing, hysteresis and noise mode.


CONCLUSIONS
A systematic analysis of the pacemaker ECG almost always allows a probable diagnosis of arrhythmias and malfunctions to be made, which can be confirmed by pacemaker control and can often be corrected at the touch of the right button to the patient's benefit.
Klinik für Innere Medizin - Kardiologie, Diabetologie & Nephrologie, Evangelisches Krankenhaus Bielefeld, Burgsteig 13, 33617, Bielefeld, Deutschland, Carsten.Israel@evkb.de.
Carsten W
CW
Israel
Lucy
L
Ekosso-Ejangue
Mohamed-Karim
MK
Sheta
D001145:Arrhythmias, Cardiac / Q000175:diagnosis* / Q000517:prevention & control*; D003936:Diagnosis, Computer-Assisted / Q000379:methods*; D003937:Diagnosis, Differential; D015716:Electrocardiography, Ambulatory / Q000379:methods*; D019317:Evidence-Based Medicine; D006801:Humans; D010138:Pacemaker, Artificial; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013813:Therapy, Computer-Assisted / Q000379:methods*