=reentrant in and around the SA Nd
Epi
-rare in kids, <1% SVT
?the impulse emerges fr SA nd and enters ara of slow conduction within atria, then recycles thru the peri-SA nd tissue to re-enter the origin site
-sinus rate usualy <220bpm
-Nl max HR for a person us ~ [208 - (age*0.7)]
-DDx- hyperthyrodi, fever, hypOvol, inappropriate sinus tachy (unlike SART, this doesnt respond to adenosine; benign, no Tx needed), POTS (bblocker, volume)