2374340 AVNN average NN interval 2 2374333 AVNN all normal R-R intervals 1 2374336 AVNN average of consecutive normal intervals 1 2374335 AVNN average of interbeat intervals 1 2374338 AVNN average of normal heart beat intervals 1 2374334 AVNN Average of normal-to-normal intervals 1 2374337 AVNN averufanin 1 2374339 AVNN parameters-average normal-to-normal interval 1