Cardiac magnetic resonance imaging investigation of sustained ventricular fibrillation in a swine model--with a focus on the electrical phase.
OBJECTIVE
We sought to develop a method to evaluate the rapidly changing cardiac dimensions during sustained ventricular fibrillation (VF). We also present details of our CPR research imaging program to facilitate this avenue of clinically important research.


BACKGROUND
The changes in cardiac dimensions occurring during the initial critical electrical phase of sustained VF are not entirely known. Conventional cardiac magnetic resonance imaging (CMR) functional imaging lacks the temporal resolution necessary to capture the dynamic changes within this early time period of sustained VF. We hypothesized that changes in the middle short axis slice of the ventricles will reflect changes in ventricular volumes accurately.


METHODS
Ventricular dimensions were determined from CMR for 30 min of untreated VF in a closed chest, closed pericardium model in seven swine. Ungated steady-state free precession images (SSFP) from the cardiac base to the apex were acquired, taking care to align the anatomical short axis (SAX) imaging planes maximally. The middle slice of the ventricles was determined as the mathematical center of the stack of SAX slices. We then compared the relative changes of right ventricle (RV) and left ventricle (LV) volumes to relative changes in mid-ventricular single slice area.


RESULTS
During 30 min of sustained VF, there was an excellent correlation between the changes in exact mid-slice area and the quantitative changes in ventricular volumes (r(2)>0.95).


CONCLUSIONS
Mid-slice area data can be used as a surrogate marker of prompt ventricular volume changes during VF. By imaging the heart 10 times faster, the rapid anatomical changes occurring during the initial few minutes of sustained VF can be understood better.
Sorrell
Vincent L
VL
Department of Medicine, Division of Cardiology, Sarver Heart Center, University of Arizona, Tucson, AZ 85724-5073, United States. vsorrell@email.arizona.edu <vsorrell@email.arizona.edu>
Bhatt
Rajan D
RD
Berg
Robert A
RA
Squire
Scott
S
Kudithipudi
Vijayasree
V
Hilwig
Ronald W
RW
Altbach
Maria I
MI
Kern
Karl B
KB
Ewy
Gordon A
GA
D000818:Animals; D004195:Disease Models, Animal; D008279:Magnetic Resonance Imaging; D013552:Swine; D014693:Ventricular Fibrillation / Q000473:pathology*