Patent ID: 8126540

Claim:
A single-chamber cardiac stimulator ( 10 ), comprising an at least partially electrically conductive housing ( 12 ); a ventricular electrode line comprising at least one electrode; at least one ventricular electrode; a second electrode; a third electrode; a first detection unit ( 52 ), which is connected via the ventricular electrode line to the at least one ventricular electrode and the second electrode wherein said first detection unit ( 52 ) is configured to record ventricular cardiac activity via a first electrocardiogram signal obtained via the at least one ventricular electrode and the second electrode; a second detection unit ( 70 ), which is connected via the ventricular electrode line to the at least one electrode of the ventricular electrode line and connected to the third electrode wherein said second detection unit ( 70 ) is configured to record a second electrocardiogram signal simultaneously with the first electrocardiogram signal via these electrodes, such that at least one of these electrodes, through which the second electrocardiogram signal is recorded, is another electrode through which the first electrocardiogram signal is recorded, so that the first and second electrocardiogram signals constitute electrocardiogram leads whose vectors are not equal to 0° or 180°; a morphology evaluation unit which is connected to the first and second detection units and is configured to determine at least one morphological signal characteristic of the first electrocardiogram signal and of the simultaneously recorded second electrocardiogram signal; a VT/SVT discrimination unit ( 76 ), which is connected to or comprises the morphology evaluation unit and is configured to utilize the at least one morphological signal characteristic determined by the morphology evaluation unit for ventricular tachycardias and supraventricular tachycardias discrimination; and, wherein the VT/SVT discrimination unit is configured to determine a ratio of signal characteristics as determined by the morphology evaluation unit and to compare said ratio with at least one first reference ratio value.