Implantable cardiac device with a shock lead

1. An implantable cardiac device comprising

a housing;

a pulse and shock generator situated within said housing and configured to generate physiologically effective electrical pulses or pace pulses;

at least one shock lead, external to said housing, connectable to said pulse generator and implantable into a patient's body to apply said physiologically effective electrical pulses to said patient's body;

a monitor to automatically detect a lead condition during a pace pulse selected from said pace pulses applied by said pulse and shock generator via said at least one shock lead as to whether said at least one shock lead is in an implanted state or in an explanted state;

wherein said lead condition is detected by said monitor with two voltage measurements associated with said pace pulse to determine a resistance comprising

a voltage measurement at a beginning of said pace pulse and

a voltage measurement at an end of said pace pulse; and,

a control, which due to a detected lead condition, automatically

enables said pulse and shock generator when all of said at least one shock lead is in said implanted state and

disables said pulse and shock generator when any of said at least one shock lead is in said explanted state.

2. The implantable cardiac device according to claim 1 , comprising an impedance measurement circuit associated with monitor configured to determine an impedance of said at least one shock lead from said measurements of the voltage at the beginning and the voltage at the end of said pace pulse as a parameter for said lead condition.

3. The implantable cardiac device according to claim 2 , wherein an enabling impedance value for said parameter for said lead condition is between 15 and 150 Ohms.

4. The implantable cardiac device according to claim 1 , wherein said monitor periodically detects said lead condition.

5. The implantable cardiac device according to claim 4 , wherein said monitor periodically detects said lead condition using a period of detection between 1 second and 1 minute.

6. The implantable cardiac device according to claim 4 , wherein an enabling impedance value between 15 and 150 Ohms is measured during a defined number of consecutive periods of detection.

7. The implantable cardiac device according to claim 4 , wherein an enabling impedance value between 15 and 150 Ohms is measured in two possible shock configurations including hv 1 to case, and hv 2 to case, by alternating measurements during a defined number of consecutive periods of detection.

8. An implantable cardiac device comprising

a housing;

a pulse and shock generator situated within said housing and configured to generate physiologically effective electrical pulses that comprise low energy shock pulses or pace pulses;

at least one shock lead, external to said housing, connectable to said pulse generator and implantable into a patient's body to apply said physiologically effective electrical pulses to said patient's body;

a monitor to automatically detect a lead condition during a low energy shock pulse selected from said low energy shock pulses applied by said pulse and shock generator via said at least one shock lead as to whether said at least one shock lead is in an implanted state in an explanted implanted state;

wherein said lead condition is detected by said monitor with detection of a time difference between a start time of the low energy shock pulse until a time that the low energy shock pulse has reached a predetermined voltage lower than a start voltage; and,

a control which automatically

enables said pulse and shock generator if the lead condition of all of said at least one shock lead is detected as said implanted state and

disables said pulse and shock generator if the lead condition of any of said at least one shock lead is detected as said explanted state.

9. The implantable cardiac device according to claim 8 , wherein said predetermined voltage lower than the start voltage is 40 percent of the start voltage.

10. The implantable cardiac device according to claim 8 , wherein said monitor periodically detects said lead condition.

11. The implantable cardiac device according to claim 10 , wherein said monitor periodically detects said lead condition with a period of detection between 1 second and 1 minute.