A technique for stable His-bundle recording and pacing: electrophysiological and hemodynamic correlates.

His-bundle electrograms recorded from intracardiac electrode catheters have been a mainstay of basic and clinical electrophysiology. However, consistent His-bundle pacing has not been as readily achieved. In 13 dogs anesthetized with sodium pentobarbital (30 mg/kg), we recorded leads II and aVR as well as the His-bundle electrogram from the aortic root. A deflectable tip multipolar catheter (4 rings, 5 mm apart) was introduced via the right jugular vein into the right ventricle (RV). In 7 dogs, using fluoroscopy, the tip was placed under the tricuspid septal leaflet. In the other 6, after thoracotomy, the same placement was made by palpation through the right atrial wall. Stable His-bundle and right bundle (Rb) branch recordings were made from distal and proximal electrode pairs, respectively. H-V intervals measured 35 +/- 6 ms from the aortic root and 33 +/- 5 ms from under the tricuspid leaflet (P = NS). Rb-V measured 25 +/- 4 ms. Consistent His-bundle pacing was accomplished from the aortic root with an average stimulus intensity of 6 +/- 10 mA and from the tricuspid leaflet at 16 +/- 8 mA (P < 0.05). In 7 anesthetized dogs we compared the hemodynamic effects of A-V sequential pacing at the same heart rates using the His-bundle recording site under the septal leaflet of the tricuspid valve (A-H pacing) or pacing from the RV apex (A-RV pacing). Under normal conditions there was a significant depression of mean blood pressure when A-RV pacing was compared with atrial pacing (AOO); but no difference was found between AOO and A-H pacing.(ABSTRACT TRUNCATED AT 250 WORDS)