Life span of ventricular fibrillation frequencies.
The nature and organization of electrical activity during ventricular fibrillation (VF) are important and controversial subjects dominated by 2 competing theories: the wavebreak and the dominant mother rotor hypothesis. To investigate spatiotemporal characteristics of ventricular fibrillation (VF), transmembrane potentials (V(m)) were recorded from multiple sites of perfused rabbit hearts using a voltage-sensitive dye and a photodiode array or a CCD camera, and the time-frequency characteristics of V(m) were analyzed by short-time fast Fourier transform (FFT) or generalized time-frequency representation with a cone-shaped kernel. The analysis was applied to all pixels to track VF frequencies in time and space. VF consisted of blobs, which are groups of contiguous pixels with a common frequency and an ill-defined shape. At any time t, several VF frequency blobs coexisted in the field of view, and the number of coexisting blobs was on average 5.9+/-2.1 (n=8 hearts) as they appeared and disappeared discontinuously with time and were not fixed in space. The life span of frequency blobs from birth to either annihilation or breakup to another frequency had a half-life of 0.39+/-0.13 second (n=4 hearts). The Ca2+ channel blocker nifedipine increased the stability of VF frequencies and reduced the number of frequency blobs progressing to a single frequency. In conclusion, VF consists of dynamically changing frequency blobs, which have a short life span and can be modified by pharmacological interventions, suggesting that VF is maintained by dynamically changing multiple wavelets.
Choi
Bum-Rak
BR
Department of Cell Biology and Physiology, University of Pittsburgh, Pittsburgh, Pa 15261, USA.
Nho
Wonchul
W
Liu
Tong
T
Salama
Guy
G
D000200:Action Potentials / Q000187:drug effects; D000465:Algorithms; D000818:Animals; D001683:Biological Clocks / Q000187:drug effects / Q000502:physiology; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020746:Calcium Channels, L-Type / Q000187:drug effects / Q000378:metabolism; D004195:Disease Models, Animal; D005260:Female; D005456:Fluorescent Dyes; D005583:Fourier Analysis; D006321:Heart / Q000187:drug effects / Q000503:physiopathology; D066298:In Vitro Techniques; D009543:Nifedipine / Q000494:pharmacology; D011817:Rabbits; D013997:Time Factors; D014693:Ventricular Fibrillation / Q000188:drug therapy / Q000503:physiopathology*
D002121:Calcium Channel Blockers; D020746:Calcium Channels, L-Type; D005456:Fluorescent Dyes; D009543:Nifedipine