Bb. Punske et al., Mechanisms of the spatial distribution of QT intervals on the epicardial and body surfaces, J CARD ELEC, 10(12), 1999, pp. 1605-1618
Citations number
51
Categorie Soggetti
Cardiovascular & Respiratory Systems","Cardiovascular & Hematology Research
Spatial Distribution of the QT Interval. Introduction: The role of QT dispe
rsion as a predictor of arrhythmia vulnerability has not been consistently
confirmed in the literature. Therefore, it is important to identify the ele
ctrophysiologic mechanisms that affect QT duration and distribution. We com
pared the spatial distributions of QT intervals (QTI) with potential distri
butions on cardiac and body surfaces and with recovery times on the cardiac
surface. We hypothesized that the measure of QTI is affected by the presen
ce of the zero potential line in the potential distribution, as well as the
sequence of recovery. We also investigated use of the STT area as a possib
le indicator of recovery times on the cardiac surface.
Methods and Results: High-resolution spatial distributions of QTI and poten
tials were determined on the body surface of human subjects and on the surf
ace of a torso-shaped tank containing an isolated canine heart, Additionall
y, spatial distributions of QTI, recovery times, and STT areas were determi
ned on the surface of exposed canine hearts. Unipolar electrograms were rec
orded during atrial and ventricular pacing for normal hearts and cases of m
yocardial infarction, Regions of shortest QTI always coincided with the loc
ation of the zero potential line on the cardiac and body surfaces, On the c
ardiac surface, in regions away from the zero line, similarities were obser
ved between the patterns of QTI and the sequence of recovery, STT areas and
recovery times were highly correlated on the cardiac surface,
Conclusion: QTI is not a robust index of local recovery time on the cardiac
surface. QTI distributions were affected by the position of the zero poten
tial line, which is unrelated to local recovery times. However, similaritie
s in the patterns of QTI and recovery times in some regions may help explai
n the frequently reported predictive value of QT dispersion. Preliminary re
sults indicate STT area may be a better index of recovery time and recovery
time dispersion on the epicardium than QTI.