[Oesophagosternal and oesophagoapical leads for registration of surface his-bundle potentials (author's transl)]

Theoretically there should be two possibilities of recording His-Bundle potentials from the body surface. Extensive amplifying and signal averaging can improve the signal to noise ratio of the His-Bundle potential. Random noise can be filtered and the periodic signal of the His bundle can be selected. On the other hand improvement of the noninvasive leading conditions could be achieved by positioning of the recording electrodes close to the structure to be investigated and by direction of the surface leading according to the anatomical axis of the bundle of His. For this purpose these new oesophagosternal and oesophagoapical leadings have been developed. The different oesophageal electrode is placed nar the upper cava-right atrial border close to the heart. The indifferent electrode is situated at the xiphisternum or at the apex of the heart. The direction of this lead is close to the direction of the anatomical axis of the His-Bundle. By this means a positive wave within the PR-segment can be registered, which we have called the "HP-wave". In a total of 17 patients these bipolar oesophageal leads were employed, in 12 cases simultaneously with the intracardiac HBE as a reference method. At rest the peak of the HP wave correlated to the maximal amplitude of the intracardiac His spike in more than 90% of patients. 4 patients were investigated by atrial pacing, in 3 cases this correlation could be found, too. Apparently the true His bundle signal can be obtained from the body surface by this new leading system. For improvement of the surface His bundle recordings, we reflect the combination of our noninvasive oseophageal lead with a modified signal averaging system with lesser amplication of the original signal.