Device for the thermal determination of cardiac volumetric performance

Claim 1

A CARDIAC CATHETER ARRANGEMENT FOR MEASURING THE VOLUME OF THE BLOOD DELIVERED BY THE HEART, CONSISTING OF A FLEXIBLE TUBULAR CATHETER MEMBER ADAPTED TO BE INTRODUCED INTO A BLOOD VESSEL, A HEATER WIRE WINDING WOUND ON SAID MEMBER, A THERMOMETRIC WINDING WOUND ON SAID MEMBER AT A SEPARATE SUBSTANTIALLY SPACED DOWNSTREAM POSITION THEREON, RELATIVE TO SAID HEATER WINDING, THE ADJACENT ENDS OF SAID TWO WINDINGS BEING SUBSTANTIALLY SPACED APART, FIRST CONNECTIONS FOR SUPPLYING AT A CONSTANT RATE HIGH-FREQUENCY HEATING CURRENT AT SHORT INTERVALS TO SAID HEATER WINDING, SECOND CONNECTIONS CONNECTED TO SAID MEASURING WINDING, AND A MEASURING BRIDGE CIRCUIT CONNECTED TO SAID SECOND CONNECTIONS SAID HEATER WINDING BEING RELATIVELY LONG IN COMPARSION WITH THE LENGTH OF SAID CATHETER MEMBER AND OF THE ORDER OF 12 CENTIMETERS SAID MEASURING BRIDGE CIRCUIT BEING A THREE-LEAD BRIDGE CIRCUIT HAVING A FIRST PAIR OF RESISTANCE ARMS OF SUBSTANTIALLY EQUAL RESISTANCE AND HAVING A SECOND PAIR OF RESISTANCE ARMS ONE OF WHICH IS SAID THERMOMETRIC MEASURING WINDING AND THE OTHER ARM OF SAID SECOND PAIR BEING A WINDING OF RESISTANCE EQUAL TO THE RESISTANCE OF SAID THERMOMETRIC MEASURING WINDING, A FIRST LEAD CONNECTED FROM THE TERMINAL OF A FIRST ONE OF SAID FIRST PAOR OF ARMS WHICH IS NOT CONNECTED TO A TERMINAL OF THE SECOND ONE OF SAID FIRST PAIR OF ARMS, TO A FIRST TERMINAL OF SAID THERMOMETRIC MEASURING WINDING WHICH IS NOT CONNECTED TO A TERMINAL OF SAID OTHER ARM OF SAID SECOND PAIR OF ARMS, A SECOND LEAD CONNECTED FROM THE SECOND OTHER TERMINAL OF SAID THERMOMETRIC WINDING TO A FIRST TERMINAL OF THE SECOND ONE OF SAID SECOND PAIR OF ARMS WHOSE RESISTANCE IS EQUAL TO THE RESISTANCE OF SAID THERMOMETRIC MEASURING WINDING, A BATTERY, AND A THIRD LEAD CONNECTED DIRECTLY FROM A FIRST POLE OF SAID BATTERY TO SAID SECOND OTHER TERMINAL OF SAID THERMOMETRIC WINDING, AND THE SECOND OTHER POLE OF SAID BATTERY BEING CONNECTED TO THE COMMON POINT OF THE TWO ARMS OF SAID FIRST PAIR OF ARMS, AND THE SECOND OTHER TERMINAL OF THE SECOND ONE OF SAID SECOND PAIR OF ARMS BEING CONNECTED TO THE TERMINAL OF THE SECOND ONE OF SAID FIRST PAIR OF ARMS WHICH IS NOT CONNECTED TO THE FIRST ONE OF SAID FIRST PAIR OF ARMS.