Method and device for filtering out baseline fluctuations from an electrocardiogram

A method for filtering out baseline fluctuations from an electrocardiogram, the method comprising the steps of:

• filtering said electrocardiogram in a filter having a lower cut off frequency;
• determining a current heartbeat rate from said electrocardiogram by detecting occurrences of QRS complexes having a temporal spacing therebetween in said electrocardiogram;
• and
• forming a reciprocal value from the temporal spacing of successive, detected QRS complexes and altering said lower cut off frequency of said filter dependent on said heartbeat rate.

An apparatus for filtering out baseline fluctuations from an electrocardiogram signal comprising:

• a filter having a signal input, a variable lower cut off frequency, a control input and an output, said electrocardiogram signal being supplied to said signal input;
• a QRS detector connected to said signal input of said filter to determine a heartbeat rate from said electrocardiogram signal, said QRS detector having an output;
• measurement means connected to said output of said QRS detector for measuring chronological spacing between successive, detected QRS complexes, said measurement means having an output;
• and
• means connected to said output of said measurement means for forming a reciprocal of said chronological spacing indicative of said heartbeat rate, said heartbeat rate being supplied to said control input of said filter for varying said variable lower cut-off frequency dependent on said heartbeat rate.