Miracapillo Gennaro, Costoli Alessandro, Addonisio Luigi, Breschi Marco, Severi Silva
Division of Cardiology, Misericordia Hospital, Grosseto, Italy.
Indian Pacing Electrophysiol J. 2008;8(4):247-57. Epub 2008 Nov 1.
Cavo-tricuspid isthmus (CTI) block is currently assessed by coronary sinus (CS) pacing or low lateral and septal atrial pacing. Occasionally, CS catheterization through the femoral route can be difficult to perform or right atrial pacing can be problematic because of catheter instability or saturation of the atrial electrograms recorded near the catheter.
Our aim was to evaluate the feasibility of assessing cavo-tricuspid isthmus block by means of right ventricular (RV) pacing in patients with ventriculo-atrial conduction, comparing it with CS pacing.
Circumannular activation was analyzed during CS and RV pacing in consecutive patients in sinus rhythm undergoing CTI ablation for typical atrial flutter. Patients without ventriculo-atrial conduction were excluded from the study. The linear lesion was created during RV pacing and split atrial signals on the ablation line were analyzed. CTI block was confirmed by analyzing local electrograms on the line of block and circumannular activation during CS and RV pacing.
Out of 31 patients, 20 displayed ventriculo-atrial conduction (64%) and were included in the study. Before ablation, during RV stimulation, the collision front of circumannular activation shifted counterclockwise in contrast with the pattern observed during CS pacing. After ablation, circumannular activation was similar during CS and RV pacing, showing fully descending lateral right atrium activation, even if double potentials registered on the ablation line were less widely split during RV pacing than CS pacing (111+/-26 ms vs 128+/-30 , p=0.0001).
In patients with ventriculo-atrial conduction, tricuspid annulus activation during CS and RV pacing is similar, before and after CTI ablation. The occurrence of split atrial electrograms separated by an isoelectric interval registered on the line of block can be detected during CS or RV pacing. In patients with difficult CS catheterization via the femoral vein, before trying the subclavian or internal jugular route, if retrograde ventriculo-atrial conduction is present, RV pacing can be an easy trick to assess isthmus block.
目前通过冠状窦（CS）起搏或低位侧壁及间隔心房起搏来评估腔静脉 - 三尖瓣峡部（CTI）阻滞。偶尔，经股静脉途径进行CS导管插入术可能难以实施，或者由于导管不稳定或导管附近记录的心房电图饱和，右心房起搏可能会出现问题。
我们的目的是评估在存在室房传导的患者中通过右心室（RV）起搏评估腔静脉 - 三尖瓣峡部阻滞的可行性，并与CS起搏进行比较。
对连续的窦性心律患者进行典型心房扑动的CTI消融时，在CS和RV起搏期间分析环周激动情况。无室房传导的患者被排除在研究之外。在RV起搏期间创建线性病变，并分析消融线上的分裂心房信号。通过分析阻滞线上的局部电图以及CS和RV起搏期间的环周激动来确认CTI阻滞。
31例患者中，20例存在室房传导（64%）并纳入研究。消融前，在RV刺激期间，环周激动的碰撞前沿逆时针移动，这与CS起搏期间观察到的模式相反。消融后，CS和RV起搏期间的环周激动相似，显示右心房外侧完全下行激动，即使消融线上记录的双电位在RV起搏期间的分裂程度比CS起搏时小（111±26毫秒对128±30毫秒，p = 0.0001）。
在存在室房传导的患者中，CTI消融前后，CS和RV起搏期间三尖瓣环的激动相似。在CS或RV起搏期间，可以检测到在阻滞线上记录的由等电位间隔分隔的分裂心房电图。对于经股静脉进行CS导管插入术困难的患者，在尝试锁骨下或颈内静脉途径之前，如果存在逆行室房传导，RV起搏可能是评估峡部阻滞的一个简便方法。
