| Abstrakt: |
Studies of the conduction patterns within the sinus node region have been limited to extracellular surface and intracellular microelectrode techniques. Even with multiple electrodes, data is limited to a finite number of discrete points within the tissue, thus pacemaker shifts, entrance block, and antegrade versus retrograde conduction differences have not been completely elucidated. To study the entire sinus node (SAN), functional perinodal boundary (FPB), and crista terminalis (CT) tissue preparation, we use a 144 element photodiode array recorded simultaneously with bipolar sensing and pacing electrograms. A wide margin of right atrial tissue including the interatrial septum (lAS), from an adult New Zealand white rabbit, was dissected and viability maintained by superfusion of 37°C, O2enriched Krebs. The tissue was stained with 2mM di-4-ANEPPS, a voltage sensitive, optically active dye. The isochronal activation patterns are constructed by linear interpolation of times in the image space between photodiode elements (625μm).Each isochronal band represents 1 ms. conduction time. Single decremental premature stimuli (560ms) were delivered into a sensed sinus rhythm (900ms) at the inferior CT (STIM). |
