Mandel et al reported an equation for describing the relationship between the spontaneous cycle length of the sinus node to the maximum recovery time. This can help identify an abnormally long nodal recovery time. The authors are from Cedars-Sinai Medical Center and the University of California Los Angeles.


According to Josephson:


maximum normal sinus node recovery time in msec =

= (1.3 * (spontaneous sinus cycle length in msec)) + 101


This is credited to Mandel et al., who gives an equation that describes the mean for P-P interval before pacing vs maximum sinus pause:


maximum sinus pause in msec =

= (1.3 * (P-P interval in msec)) + 46.12


The normal range is this line +/- 2 SD. The shaded area in Figure 3 of Mandel et al is +/- 1 SD. If 101 - 46.12 = 2 SD, then 1 SD is 27.4 msec.


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