Apparatus for and method of programming the minimum energy threshold for pacing pulses to be applied to a patient's heart

Apparatus for programming a pacing generator to effect a threshold mode of operation in which the minimum energy level required for the generator's stimulating pulses to stimulate a patient's heart is determined, the pacing generator including first memory means for storing an original value of the energy level before initiation of the threshold mode and a second memory means for storing the values of the energy level employed when the pacing generator is operative in its threshold mode, said apparatus comprising:

• (a) keyboard means manually manipulatable for operating said programming apparatus in its threshold mode;
• (b) means responsive to the initiation by said keyboard means of operation in the threshold mode for determining the original value of the energy level before the pacing generator enters in its threshold mode;
• (c) transmitter means for transmitting encoded signals from said apparatus indicative of the desired energy level of the stimulating pulses to be applied by the pacing generator to the patient's heart;
• (d) conductor means coupling said programming apparatus to the patient for receiving the patient's heart activity signals including the stimulating pulses applied by the pacing generator to the patient's heart;
• (e) computer means for receiving the original value of the energy level from said determining means for decrementing the original value and for causing said transmitter means to transmit a new encoded signal commanding the pacing generator to apply stimulating pulses to the decremented energy level to the patient's heart, the first memory means storing the original energy level and the second temporary memory means storing the values of the decremented energy level;
• and
• (f) display means coupled to said determining means for displaying the value of the original energy level and connected to said computing means for displaying the current decremented value of the energy level.

A method of operating a pacing generator implanted within a patient's body to effect a threshold mode of operation in which the minimum energy level required for the stimulating pulses generated by the pacing generator to stimulate the patient's heart is determined, said method comprising the steps of:

• (a) upon initiation of the threshold mode of operation of the pacing generator, determining the original energy level of the stimulating pulses as applied by the pacing generator to the patient's heart;
• (b) decrementing the original value of the energy level by an incremental amount;
• (c) encoding the decremented energy levels;
• (d) transmitting the encoded signals to the pacing generator indicative of the desired decremented level of the stimulating pulses to be applied by the pacing generator to the patient's heart;
• and
• (e) providing a visual manifestation of the decremented values of the energy level as transmitted to the pacing generator.