Tunable ECG sensing filter for pacemaker

A tunable electrocardiogram sensing filter for a heart pacemaker comprising:

• a tapped analog delay device having a signal input and a clock input and a plurality of taps;
• a summing amplifier;
• a plurality of load resistors connecting the taps of the analog delay device to the summing amplifier, said load resistors having values defining a tap weight function to form a bandpass characteristic for the filter;
• means connected for applying the patient's electrocardiogram signals from a lead terminal of the pacemaker to the signal input of the tapped analog delay device;
• a clock connected for providing clock signals to the clock input of the tapped analog delay;
• and
• means for adjusting the frequency of said clock to adjust the frequency of the passband of the filter.

An implantable demand pacemaker, comprising:

• terminal means for connection to a patient's heart;
• pulse generating means connected for periodically applying stimulating pulses to said terminal means for stimulating the patient's heart;
• a tapped analog delay device having a signal input, a clock input and a plurality of output taps;
• means connecting said terminal means to the signal input means for the tapped analog delay device for conveying electrical signals from the patient's heart thereto;
• a clock connected for providing clock signals to the clock input of said tapped analog delay device;
• a summing amplifier;
• a plurality of load resistors connecting the output taps of said analog delay device to the summing amplifier, said load resistors having values defining a tap weight function to form a bandpass filter characteristic for the tapped analog delay device;
• remotely programmable means connected to said clock for adjusting the frequency thereof so that said bandpass frequency may be adjusted to match a range of frequency components of the patient's electrocardiogram;
• and
• means connecting the output of said summing amplifier to said pulse generating means, and operable upon receipt of a signal from the summing amplifier indicating occurrence of a depolarization of the patient's heart to reset and inhibit said pulse generating means from delivering a stimulating pulse.