Improvements in atrial fibrillation detection for real-time monitoring

A 2-channel ECG with irregular R-R intervals and clear P waves. Because of the irregular R-R interval, the R-R interval–based algorithm erroneously reports an AF episode that lasts 7 minutes. The beginning of this false episode of atrial fibrillation is shown as (AFIB) on channel 2. The algorithm with combined R-R and P wave analysis does not misclassify the irregular rhythm as AF because the P waves are correctly detected.

An example of a nonsymmetric hysteresis counter with minimum of 4, threshold of 0, and maximum of 2 is shown. The dashed line on the top indicates the output of the decision tree classifier. The dot-dashed line in the middle illustrates the outcome of the hysteresis counter that counts up with every AF episode and counts down with any non-AF segment. The solid line at the bottom represents the behavior of AF alarm generator. The algorithm turns the AF alarm on if the hysteresis count rises above the predefined threshold of 0 and turns the AF alarm off if the hysteresis count drops below the defined threshold.