Epicardial organization of human ventricular fibrillation.
OBJECTIVE
The objective of this study was to test the hypothesis that on the epicardium of the in vivo human heart, ventricular fibrillation (VF) consists of chaotic small wavefronts that constantly change paths.


BACKGROUND
Despite the significance of VF to cardiovascular mortality, little is known about the wavefronts that constitute VF in humans.


METHODS
In 9 patients undergoing cardiac surgery, a single VF episode was induced by rapid pacing immediately after institution of cardiopulmonary bypass while recordings were made from 504 electrodes spaced 2 mm apart in a 20 cm(2) plaque held against the anterior left ventricle epicardium. A total of 26 segments of VF, each 2 s long, were analyzed. A computer algorithm identified individual wavefronts and classified them into groups that followed similar activation sequences.


RESULTS
The mean activation rate was 5.8 +/- 1.8 (mean +/- SD) cycles/s. The wavefronts during each epoch were grouped into 9.4 +/- 7.1 different activation pathways, and 8.3 +/- 2.3 wavefronts followed each pathway. Individual wavefronts spread to activate an area of 5.1 +/- 3.0 cm(2) in the mapped region. The majority of the wavefronts propagated into the mapped region and/or propagated out of the mapped region into adjacent tissue, suggesting that the wavefronts were larger than 5.1 cm(2). Reentry was identified in only 16 of the 26 (62%) 2-s segments, always completed <2 cycles, and lasted for 9.5 +/- 6.6% of these 16 epochs, which is 5.8% of the total duration of all the segments analyzed.


CONCLUSIONS
VF wavefronts on the human epicardium are usually large, repeatedly follow distinct pathways, and only occasionally reenter. If these results for the left ventricular epicardium are representative of those for the entire ventricular mass, they do not support the hypothesis that human VF consists of small, constantly changing wavefronts, but rather suggest that there is significant organization of human VF.
Nanthakumar
Kumaraswamy
K
Division of Cardiovascular Medicine, University of Alabama at Birmingham, 35294, USA. kn@crml.uab.edu
Walcott
Gregory P
GP
Melnick
Sharon
S
Rogers
Jack M
JM
Kay
Matthew W
MW
Smith
William M
WM
Ideker
Raymond E
RE
Holman
William
W
D000200:Action Potentials; D000328:Adult; D000368:Aged; D000465:Algorithms; D018780:Body Surface Potential Mapping; D002315:Cardiopulmonary Bypass; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D006352:Heart Ventricles / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010496:Pericardium / Q000503:physiopathology*; D011446:Prospective Studies; D013997:Time Factors; D014693:Ventricular Fibrillation / Q000503:physiopathology*