Effect of underlying heart disease on the frequency content of ventricular fibrillation in the dog heart.
Although prior studies have examined the frequency content of local electrogram characteristics during fibrillation, little is know about the effects of underlying heart disease on these parameters. This study was designed to compare the frequency content of local electrograms during VF in canine models of acute ischemia, subacute infarction, and chronic myocardial infarction (MI) to those in control animals to test the hypothesis that underlying heart disease can alter the basic characteristics of VF. VF was induced using burst pacing in three groups of mongrel dogs. Five dogs were evaluated 8 weeks after LAD occlusion MI, five were evaluated 5 days after experimental MI, and 5 had VF induced before (control) and immediately after LAD occlusion (ischemia). During VF, unipolar electrograms were recorded from 112 sites on the anterior LV and electrograms were evaluated 15 and 30 seconds after VF initiation in each group. Electrograms were analyzed by fast Fourier transform. No significant time dependent changes in VF characteristics were noted. The peak frequency was highest in control animals and 8-week MI, intermediate in 5-day MI, and lowest in acute ischemia (P < 0.01 for pairwise comparisons). In contrast, the fractional of energy within a bandwidth of 25% peak amplitude was highest in acute ischemia, (P < 0.001) and similar in the other three groups. Infarction decreased total energy by approximately 50%. In conclusion, the pressure of ischemia or infarction alters the frequency content of VF in a complex fashion. In addition to decreasing the peak frequency, the shape of the power spectral curve is altered in models of structural heart disease. These results suggest that the electrophysiological changes produced by infarction or ischemia alter the structural organization of ventricular fibrillation.
Jacobson
J T
JT
Department of Medicine, Northwestern University, Chicago, Illinois, USA.
Johnson
D
D
Horvath
G
G
Goldberger
J
J
Kadish
A
A
D000818:Animals; D004195:Disease Models, Animal; D004285:Dogs; D004562:Electrocardiography; D005583:Fourier Analysis; D006331:Heart Diseases / Q000503:physiopathology*; D017202:Myocardial Ischemia / Q000503:physiopathology / Q000662:veterinary; D013997:Time Factors; D014693:Ventricular Fibrillation / Q000503:physiopathology*