Abstract: The apparatus for pacing a heart in accordance with the heart rate needed to produce a required cardiac output while the person is exercising, comprises a pacer adapted to be implanted in a human body and having a pulse generator and control circuitry (e.g. a microprocessor) therein, a pacing lead adapted to be implanted in a heart and having a distal electrode adapted to engage and supply pacing pulses to a right ventricle of a heart, and a pO.sub.2 sensor for sensing pO.sub.2 of the blood in the heart. An algorithm or routine utilizing same are stored in the control circuitry (microprocessor) and are adapted to relate pO.sub.2 and/or .DELTA.pO.sub.2 with the required heart rate or change in heart rate, .DELTA.R, needed to supply a desired cardiac output and to cause the pacer to pace the heart at the required heart rate when the heart is not naturally paced.

Abstract: The apparatus for pacing a heart in accordance with the heart rate needed to produce a required cardiac output while the person is exercising, comprises a pacer adapted to be implanted in a human body and having a pulse generator and control circuitry (e.g. including a microprocessor) therein, a pacing lead adapted to be implanted in a right ventricle in a heart and having a distal electrode adapted to engage and supply pacing pulses to the apex of the right ventricle and a pressure sensor or impedance sensing electrode mounted in or on the lead.

Abstract: The apparatus for pacing a heart in accordance with the heart rate needed to produce a required cardiac output relative to the partial pressure of carbon dioxide in the blood, pCO.sub.2, while the person is exercising comprises a pacer adapted to be implanted in a human body and having a pulse generator and control circuitry (e.g. including a microprocessor) therein, a pacing lead adapted to be implanted in a heart and having a distal electrode adapted to engage and supply pacing pulses to a right ventricle of a heart and a pCO.sub.2 sensor for sensing pCO.sub.2 of the blood in the heart. An algorithm and routine utilizing same are stored in the control circuitry (microprocessor) and are adapted to relate pCO.sub.2 with the required heart rate or change in rate, .DELTA.R, needed to supply a desired cardiac output and to cause the pacer to pace the heart at the required heart rate when the heart is not naturally paced.

Abstract: The apparatus for pacing a heart in accordance with the heart rate needed to produce a required cardiac output while the person is exercising, comprises a pacer adapted to be implanted in a human body and having a pulse generator and control circuitry (e.g. including a microprocessor) therein, a pacing lead adapted to be implanted in a heart and having a distal electrode adapted to engage and supply pacing pulses to a right ventricle of a heart and, a pacer sensor for sensing right ventricular systolic pressure mounted on the lead. An algorithm and routine utilizing same are stored in the control circuitry (microprocessor) and are adapted to relate right ventricular systolic pressure and/or the time derivative of the pressure sensed with the required heart rate needed to supply a desired cardiac output and to cause the pacer to pace the heart at the required heart rate when the heart is not naturally paced.

Abstract: An in vivo electrochemical monitoring device is formed by a catheter-like member which terminates in a closed end having a wall with a fixed opening to admit fluid to be tested, such as blood in an artery. An electrochemical sensor, such as an ISFET device for monitoring the concentration of a particular ion in blood, is mounted inside the tube at a fixed location below the opening preferably a larger sensing chamber. An infusion channel in the tube is arranged to flood the sensor with a fluid of known chemical properties so that the sensor output can be calibrated. Under pressure the calibration fluid expels the test fluid out of the tube or chamber via the fixed opening. A method of constructing a suitable chamber on an ISFET wafer is also disclosed.

Abstract: An in vivo electrochemical monitoring device is formed by a catheter-like member which terminates in a closed end having a wall with a fixed opening to admit fluid to be tested, such as blood in an artery. An electrochemical sensor, such as an ISFET device for monitoring the concentration of a particular ion in blood, is mounted inside the tube at a fixed location below the opening preferably a larger sensing chamber. an infusion channel in the tube is arranged to flood the sensor with a fluid of known chemical properties so that the sensor output can be calibrated. Under pressure the calibration fluid expels the test fluid out of the tube or chamber via the fixed opening. A method of constructing a suitable chamber on an ISFET wafer is also disclosed.