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.
Department of Cell Biology and Physiology, University of Pittsburgh, Pittsburgh, Pa 15261, USA.
Bum-Rak
BR
Choi
Wonchul
W
Nho
Tong
T
Liu
Guy
G
Salama
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