Jm. Kalman et al., A MATHEMATICAL-MODEL OF SINUS NODE FUNCTION - VALIDATION BY RECORDINGOF SINUS NODE ELECTROGRAMS, The American journal of physiology, 266(2), 1994, pp. 80000681-80000692
We have applied a mathematical function to model sinus node recovery a
fter atrial pacing at different cycle lengths in 13 autonomically dene
rvated, anesthetized canines. This model provides ''pure'' indexes of
sinoatrial conduction and of suppression of automaticity. We compared
sinoatrial conduction computed from the model (SACT(c)) with sinoatria
l conduction measured directly utilizing a catheter recording the sinu
s node electrogram (SACT(d)) to test the validity of the model. We use
d both the model and the sinus node electrogram to further define even
ts after pacing. There was close agreement between SACT(c) and SACT(d)
with correlation coefficients at pacing cycle lengths of 20 and 50% b
elow resting of 0.86 (P < 0.0001) and 0.78 (P < 0.0001), respectively.
We verified that the conventional sinus node recovery time is due bot
h to suppression of automaticity and prolongation of sinoatrial conduc
tion. Sinoatrial conduction time returned rapidly to normal over 1-3 b
eats, whereas automaticity recovered exponentially over 20-40 postpaci
ng intervals. The model accurately describes postpacing phenomena and
has the potential to provide a useful adjunct to the measurement of th
e sinus node electrogram for assessment of sinus node function in the
experimental laboratory.