Mapping实验可标测兴奋起搏点的位置并追踪其变化
此案例中，科研工作者发现了心房与心室交界处的组织在分子生物学研究中证明有类似起搏细胞的蛋白表达，但未证实有无起搏功能，初次投稿后，被要求补做mapping实验。
该mapping实验首先在包括完整窦房结的心房组织上（图A）（有氧恒温灌流，该组织可维持电生理活性达一周之久）进行标测，可看到电活动稳定规律，电活动从窦房结方向起搏并传导到整个心房组织（图B）。剪掉窦房结组织，只留部分心房组织，心室组织（ 图C，解剖时完全避开房室结，保证此组织无房室结存留），再用另一个小尺寸矩阵电极标测，可发现缓慢、不规律电活动由房室连接处传出，并在给异丙肾上腺素时，起搏点位置发生转移（图D）。该实验从电生理功能上证实了房室交界处的组织有引起异位起搏的功能。
(A). Preparation of rear wall of right atrium containing sinus node (SN) and right ring. Boxes shows position of mapping arrays covering area of SN (8×8 extracellular electrodes) and right ring (6×10 extracellular electrodes). Leading pacemaker site (identified as site of earliest activation) located in SN, and anterograde conduction in right atrial free wall. Arrows show directionof AP conduction from SN to rest of preparation. (B). Preparation containing right ring only (SN and AVN removed), the box shows position of mapping array (6×10 extracellular electrodes) and activation map shows retrograde conduction from pacemaker site to remainder of right atrium. (C). Typical intracellular action potentials recorded from pacemaker sites in right ringand SN.
