Unipolar electrograms from noncontact mapping during atrial pacing discriminated endocardial from subendocardial activation origin (PPV 0.96), but did not predict origin at the ventricular level.
Does the morphology of reconstructed unipolar electrograms predict the origin of electrical activation (endocardial vs subendocardial) in the atrial and ventricular walls?
Morphological characteristics of unipolar electrograms from noncontact mapping can discriminate endocardial versus subendocardial origin of activation in the atrium, but not in the ventricle, in a porcine model.
p-value: p=<0.01
Clinical data using the noncontact mapping system (Ensite 3000) suggest that characteristics of the reconstructed unipolar electrograms may predict the origin of electrical activation within the atrial and ventricular walls (endocardial vs myocardial vs epicardial origin). Experimental data are lacking. In ten open-chest pigs (mean body weight 62 kg) cardiac pacing was performed at a cycle length of 600 ms with a pulse width of 2 ms and twice diastolic threshold from the endo-, the myo-, and the epicardium, respectively. Pacing was undertaken at three right atrial and three left ventricular sites, and cardiac activation was recorded with the Ensite system. Reconstructed unipolar electrograms at the location of earliest endocardial activation assessed by color coded isopotential maps were analyzed systematically for differences in morphology. The positive predictive value of atrial electrograms exhibiting an initial R wave during pacing for a subendocardial origin (i.e., myocardial or epicardial) was 0.96. The negative predictive value was 0.48. Electrograms generated during myocardial pacing exhibited increased maximal negative voltage and maximal dV/dt (-3 +/- 1.8 mV, -798 +/- 860 mV/ms, respectively) than the electrograms obtained during endocardial (-2 +/- 1 mV, -377 +/- 251 mV/ms, respectively) and epicardial pacing (-2.1 +/- 0.7 mV, -440 +/- 401 mV/ms, respectively, P<0.01 for both parameters). During pacing at the left ventricular wall, occurrence of an initial R wave did not differ significantly between electrograms reconstructed during endocardial and subendocardial pacing. All other characteristics of the unipolar ventricular electrograms analyzed, except latency, did not differ significantly when compared to stimulation depth. Morphological characteristics of unipolar electrograms generated by the noncontact mapping system during pacing of the atrium allowed for discrimination of an endocardial versus a subendocardial origin of activation. At the ventricular level, characteristics of unipolar electrograms did not predict the origin of cardiac activation in this experimental setting.
Kroll et al. (Wed,) conducted a other in Origin of electrical activation (n=10). Cardiac pacing from endo-, myo-, and epicardium vs. Different pacing depths was evaluated on Maximal negative voltage and maximal dV/dt (p=<0.01). Unipolar electrograms from noncontact mapping during atrial pacing discriminated endocardial from subendocardial activation origin (PPV 0.96), but did not predict origin at the ventricular level.
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