A method and apparatus to detect irregular heart activity based upon a
ventricular activity analysis, P wave activity, similarities in R wave to
R wave intervals, and a state evaluation. The invention includes a beat
classification module that receives ECG information as an input. The beat
classification module determines whether the heart beat being analyzed
falls within classifications that are suitable for use in analyzing
whether an irregular condition exists. If the beat falls within a class
suitable for analysis, the ECG information is fed to an interval
calculator. The interval calculator determines the interval between
successive R waves. The information from the interval calculator is
provided to a probability engine and to a contextual analysis module. The
probability engine is designed to detect atrial fibrillation based upon
beat classification and RR interval values from the interval calculator.
The probability engine outputs a state variable that indicates a
probability of whether an irregular condition is present. The contextual
analysis module matches predefined maps to a running map of the current
ECG information. The contextual analysis module also determines the
similarity between consecutive RR intervals and checks for sequences of
matching classes. ECG information is also supplied to a P wave detection
module to detect the presence of P waves. Information from the probability
analysis engine, the contextual analysis module, and the P wave detection
module is then provided to a state evaluation module. The state evaluation
module uses the outputs of the three modules to determine whether an
irregular condition exists.