Tripolar catheter apparatus

Claim 2

A tripolar catheter apparatus connectable to a bipolar demand cardiac pacer having a common pacer terminal pair for providing both cardiac depolarization sensing and cardiac stimulation in a human patient dependent on the mode of said pacer, said sensing being provided in a sensing mode and said stimulation being provided in a stimulation mode, said catheter being insertable through a portion of the patient's curculatory system into the heart, said tripolar catheter apparatus comprising a first catheter terminal connected to one pacer terminal of said pacer common terminal pair, a second catheter terminal connected to the other pacer terminal of said pacer common terminal pair, a first proximal electrode, a second medial electrode, a third distal electrode and switch means responsive to the provision of a cardiac stimulus from said pacer, said switch means being connected between said first catheter terminal and said medial and proximal electrodes for selecting either said medial or proximal electrode dependent on the provision of said cardiac stimulus from said pacer, said distal electrode being connected to said other catheter terminal irrespective of said selection of said medial or distal electrode, said distal and medial electrodes comprising intra-ventricular electrodes, said proximal electrode comprising an extra-ventricular electrode, said switch means being responsive to the provision of said cardiac stimulus from said pacer in said pacer stimulating mode for providing said stimulus to the heart between said intra-ventricular distal and medial electrodes during the presence of said cardiac stimulus, said switch means being responsive to said pacer sensing mode for providing said depolarization sensing from the heart between said intra-ventricular distal electrode and said extra-ventricular proximal electrode, whereby said bipolar demand cardiac pacer is usable as a tripolar demand cardiac pacer.

Claim 3

A tripolar catheter apparatus in accordance with claim 1 wherein said medial electrode is connected in parallel to said proximal electrode through a diode switch means, said diode switch means being conductive in response to the presence of said cardiac stimulus at said first catheter terminal for providing said cardiac stimulus between said medial and distal electrodes.

Claim 4

A tripolar catheter apparatus in accordance with claim 2 wherein a first resistive impedance R is connected between said proximal electrode and said first catheter terminal, a physiological impedance Z p being present between said proximal and distal electrodes when said catheter apparatus is connected to the heart, and said cardiac pacer has an associated input impedance Z i with said resistive impedance R being related to said physiological impedance Z p in accordance with a voltage divider ratio of Z p /(R+Z p ) when said cardiac stimulus is present at said first catheter terminal, where Z p <R.

Claim 5

A tripolar catheter apparatus in accordance with claim 3 wherein in said pacer sensing mode, said resistive impedance R is further related to said cardiac pacer input impedance Z i in accordance with a voltage divider ratio of Z i /(R+Z i ), where Z p <R<Z i .

Claim 6

A tripolar catheter apparatus in accordance with claim 4 wherein the value of the ratio Z p /(R+Z p ) is in the range of 4% to 25%.

Claim 7

A tripolar catheter apparatus in accordance with claim 5 wherein the value of the ratio Z p /(R+Z p ) is substantially equal to 5%.

Claim 8

A tripolar catheter apparatus in accordance with claim 5 wherein the value of the ratio Z i /(R+Z i ) is in the range of 80% to substantially 100%.

Claim 9

A tripolar catheter apparatus in accordance with claim 7 wherein the value of the ratio Z i /(R+Z i ) is substantially equal to 90%.

Claim 10

A tripolar catheter apparatus in accordance with claim 8 wherein the value of the ratio Z p /(R+Z p ) is substantially equal to 5%.

Claim 11

A tripolar catheter apparatus in accordance with claim 4 wherein the value of the ratio Z i /(R+Z i ) is in the range of 80% to substantially 100%.

Claim 12

A tripolar catheter apparatus in accordance with claim 2 wherein said diode switch means comprises a bidirectional diode switch means conductive in response to the presence of said cardiac stimulus at said first catheter terminal irrespective of the polarity of said first catheter terminal.

Claim 13

A tripolar catheter apparatus in accordance with claim 11 wherein said bidirectional diode switch means comprises a pair of diodes connected in parallel with opposite polarities.

Claim 14

A tripolar catheter apparatus in accordance with claim 12 wherein said bidirectional diode switch means further comprises a second resistive impedance R 2 connected in parallel with said parallel connected diode pair for providing a high impedance leakage current path in the opposite direction to the normal direction of current flow to said medial electrode.

Claim 15

A tripolar catheter apparatus in accordance with claim 2 wherein said diode switch means comprises at least a first diode and a resistive impedance R 2 connected in parallel with said first diode for providing a high impedance leakage current path in the opposite direction to the normal direction of current flow to said medial electrode.

Claim 16

A tripolar catheter apparatus in accordance with claim 14 wherein another resistive impedance R is provided between said proximal electrode and said first catheter terminal, the value of said resistive impedance R 2 being at least twice the value of said other resistive impedance R.

Claim 17

A tripolar catheter apparatus in accordance with claim 1 wherein a first resistive impedance R is connected between said proximal electrode and said first catheter terminal, a physiological impedance Z p being present between said proximal and distal electrodes when said catheter apparatus is connected to the heart, and said cardiac pacer has an associated input impedance Z i with said resistive impedance R being related to said distal-proximal electrode physiological impedance Z p in accordance with a voltage divider ratio of Z p /(R+Z p ) when said cardiac stimulus is present at said first catheter terminal, where Z p <R.

Claim 18

A tripolar catheter apparatus in accordance with claim 16 wherein in said pacer sensing mode, said resistive impedance R is further related to said cardiac pacer input impedance Z i in accordance with a voltage divider ratio of Z i /(R+Z i ), where Z p <R<Z i .

Claim 19

A tripolar catheter apparatus in accordance with claim 17 wherein the value of the ratio Z i /(R+Z i ) is in the range of 80% to substantially 100%.

Claim 20

A tripolar catheter apparatus in accordance with claim 16 wherein the the value of the ratio Z p /(R+Z p ) is in the range of 4% to 25%.

Claim 21

A tripolar catheter apparatus in accordance with claim 19 wherein the value of the ratio Z i /(R+Z i ) is in the range of 80% to substantially 100%.

Claim 22

A tripolar catheter apparatus in accordance with claim 1 wherein said first catheter terminal is an anode and said second catheter terminal is a cathode.

Claim 23

In a cardiac pacing system comprising a bipolar demand cardiac pacer having a common pacer terminal pair for providing both cardiac depolarization sensing and cardiac stimulation in a human patient dependent on the mode of said pacer, said sensing being provided in a sensing mode and said stimulation being provided in a stimulation mode, and a catheter means insertable through a portion of the patient's circulatory system into the heart, the improvement comprising a tripolar catheter apparatus as said catheter means, said tripolar catheter apparatus comprising a first catheter terminal connected to one pacer terminal of said pacer common terminal pair, a second catheter terminal connected to the other pacer terminal of said pacer common terminal pair, a first proximal electrode, a second medial electrode, a third distal electrode and switch means responsive to the provision of a cardiac stimulus from said pacer, said switch means being connected between said first catheter terminal and said medial and proximal electrodes for selecting either said medial or proximal electrode dependent on the provision of said cardiac stimulus from said pacer, said distal electrode being connected to said other catheter terminal irrespective of said selection of said medial or distal electrode, said distal and medial electrodes comprising intra-ventricular electrodes, said proximal electrode comprising an extra-ventricular electrode, said switch means being responsive to the provision of said cardiac stimulus from said pacer in said pacer stimulating mode for providing said stimulus to the heart between said intra-ventricular distal and medial electrodes during the presence of said cardiac stimulus, said switch means being responsive to said pacer sensing mode for providing said depolarization sensing from the heart between said intra-ventricular distal electrode and said extra-ventricular proximal electrode, whereby a tripolar demand cardiac pacing system is provided.

Claim 24

In a cardiac pacing system comprising a bipolar demand cardiac pacer having a common pacer terminal pair for providing both cardiac depolarization sensing and cardiac stimulation in a human patient dependent on the mode of said pacer, said sensing being provided in a sensing mode and said stimulation being provided in a stimulation mode, and a catheter means insertable through a portion of the patient's circulatory system into the heart, the improvement comprising a tripolar catheter apparatus as said catheter means, said tripolar catheter apparatus comprising a first catheter terminal connected to one pacer terminal of said pacer common terminal pair, a second catheter terminal connected to the other pacer terminal of said pacer common terminal pair, a first proximal electrode, a second medial electrode, a third distal electrode and switch means responsive to the provision of a cardiac stimulus from said pacer, said switch means being connected between said first catheter terminal and said medial and proximal electrodes for selecting either said medial or proximal electrode dependent on the provision of said cardiac stimulus from said pacer, said distal electrode being connected to said other catheter terminal irrespective of said selection of said medial or distal electrode, said distal and medial electrodes comprising intra-ventricular electrodes, said proximal electrode comprising an extra-ventricular electrode, said switch means being responsive to the provision of said cardiac stimulus from said pacer in said pacer stimulating mode for providing said stimulus to the heart between said intra-ventricular distal and medial electrodes during the presence of said cardiac stimulus, said switch means being responsive to said pacer sensing mode for providing said depolarization sensing from the heart between said intra-ventricular distal electrode and said extra-ventricular proximal electrode, whereby a tripolar demand cardiac pacing system is provided.

Claim 25

An improved cardiac pacing system in accordance with claim 22 wherein said medial electrode is connected in parallel to said proximal electrode through a diode switch means, said diode switch means being conductive in response to the presence of said cardiac stimulus at said first catheter terminal for providing said cardiac stimulus between said medial and distal electrodes.

Claim 26

An improved cardiac pacing system in accordance with claim 23 wherein a first resistive impedance R is connected between said proximal electrode and said first catheter terminal, a physiological impedance Z p being present between said proximal and distal electrodes when said catheter apparatus is connected to the heart, and said cardiac pacer has an associated input impedance Z i with said resistive impedance R being related to said physiological impedance Z p in accordance with a voltage divider ratio of Z p /(R+Z p ) when said cardiac stimulus is present at said first catheter terminal, where Z p <R.

Claim 27

An improved cardiac pacing system in accordance with claim 24 wherein in said pacer sensing mode, said resistive impedance R is further related to said cardiac pacer input impedance Z i in accordance with a voltage divider ratio of Z i /(R+Z i ), where Z p <R<Z i .

Claim 28

An improved cardiac pacing system in accordance with claim 25 wherein the value of the ratio Z p /(R+Z i ) is in the range of 4% to 25%.

Claim 29

An improved cardiac pacing system in accordance with claim 26 wherein the value of the ratio Z i /(R+Z i ) is in the range of 80% to substantially 100%.

Claim 30

An improved cardiac pacing system in accordance with claim 25 wherein the value of the ratio Z i /(R+Z i ) is in the range of 80% to substantially 100%.

Claim 31

An improved cardiac pacing system in accordance with claim 23 wherein said diode switch means comprises a bidirectional diode switch means conductive in response to the presence of said cardiac stimulus at said first catheter terminal irrespective of the polarity of said first catheter terminal.

Claim 32

An improved cardiac pacing system in accordance with claim 29 wherein said bidirectional diode switch means comprises a pair of diodes connected in parallel with opposite polarities.

Claim 33

An improved cardiac pacing system in accordance with claim 30 wherein said bidirectional diode switch means further comprises a second resistive impedance R 2 connected in parallel with said parallel connected diode pair for providing a high impedance leakage current path in the opposite direction to the normal direction of current flow to said medial electrode.

Claim 34

An improved cardiac pacing system in accordance with claim 23 wherein said diode switch means comprises at least a first diode and a second resistive impedance R 2 connected in parallel with said first diode for providing a high impedance leakage current path in the opposite direction to the normal direction of current flow to said medial electrode.