Introduction:
Stability of reentry during VF may depend on the dynamics of rotor cores. We determined the mobility of rotors during human VF using global epicardial mapping and phase singularity analysis.
Methods:
In 10 patients undergoing cardiac surgery (6 with coronary artery disease; 4 with aortic valve disease), VF was induced by burst pacing prior to (n=7) or immediately following (n=3) the onset of cardiopulmonary bypass. For each subject, a 20 – 40 s episode of fibrillatory activity was sampled at 1 kHz using an epicardial sock containing 256 unipolar contact electrodes connected to a UnEmap system. Trajectories of persistent epicardial rotors (singularities of phase maps, based on de-trended voltage versus its Hilbert transform, lasting for > 1000 ms) were tracked. The mean core location was determined across the lifetime of each persistent rotor. The rotor was classified as stationary if its core remained within 15 mm of the mean location for more than 90% of its duration.
Results:
Using the above criteria, the numbers of mobile and stationary rotors varied from patient-to-patient (see figure
). In all but one patient, there were more mobile than stationary rotors. Over all patients, the mean ± SD number of mobile rotors (32 ± 21) was significantly greater than stationary rotors (7 ± 6, P<0.01).
Conclusions:
At least one stationary rotor was always present during human VF, but it is predominantly characterised by a small number of persistent mobile rotors.
Singularity analysis and analytic solutions for the Benney–Gjevik equations
