Liuba Ioan, Walfridsson Håkan
Department of Cardiology, University Hospital Linköping, 581 85 Linköping, Sweden.
Europace. 2008 Oct;10(10):1195-204. doi: 10.1093/europace/eun192. Epub 2008 Jul 28.
Fractionated electrograms are often noted during mapping of focal atrial tachycardia (FAT). This finding suggests poor cell-to-cell coupling, which is thought to be an important prerequisite in the process of ectopic impulse initiation and propagation. The purpose of the present study was to assess the electrogram fractionation in the vicinity of the earliest activation site and in the remaining atrium in these patients.
Thirteen patients with FAT (age 48 +/- 17 years) who underwent catheter ablation were investigated. Mapping was performed with the CARTO system. Electrogram fractionation was assessed on the basis of the number of negative deflections, both in the region surrounding the earliest activation site and in the remaining atrium. Unipolar and bipolar peak-to-peak voltage and bipolar electrogram duration were also studied. All patients underwent successful radiofrequency ablation. A higher degree of electrogram fractionation existed in the region surrounding the earliest activation site and activated within the first 15 ms when compared with the remaining atrium (incidence of bipolar electrograms with multiple negative deflections: 88 vs. 79%, P < 0.0001; incidence of unipolar electrograms with multiple negative deflections: 56 vs. 43%, P = 0.0001). The peak-to-peak voltage in the region activated within the first 15 ms was less than that in the remaining atrium (bipolar voltage: 1.33 +/- 0.99 vs. 1.61 +/- 1.11 mV, P < 0.001; unipolar voltage: 1.75 +/- 0.92 vs. 1.95 +/- 1.11 mV, P = 0.0188). There were no significant differences in bipolar electrogram duration. Within the region activated during the first 15 ms, from the periphery to the earliest activation site, there was a gradual increase in electrogram fractionation (incidence of bipolar electrograms with multiple negative deflections gradually increasing from 82 to 100% and incidence of unipolar electrograms with multiple negative deflections increasing from 56 to 90%), as well as a gradual decrease in peak-to-peak voltage (bipolar voltage gradually decreasing from 1.47 +/- 1.06 to 0.89 +/- 0.54 mV, P < 0.0001; unipolar voltage gradually decreasing from 1.89 +/- 0.94 to 1.30 +/- 0.63 mV, P < 0.0001). Irregular, closely spaced isochrones were also noted in the region activated during the first 15 ms. The area of this region was 4.88 +/- 3.59 cm(2).
Increased electrogram fractionation exists within a relatively wide region around the tachycardia origin when compared with the remaining atrium. Moreover, this region is electrically heterogeneous, as suggested by the fact that the degree of electrogram fractionation increases gradually whereas the electrogram voltage decreases gradually towards the earliest activation site. These findings suggest that a non-discrete atrial region with gradually changing electrophysiological properties may underlie the substrate of FAT.
在局灶性房性心动过速（FAT）标测过程中常可记录到碎裂电图。这一发现提示细胞间耦联不佳，而细胞间耦联不佳被认为是异位冲动起始和传导过程中的一个重要前提条件。本研究的目的是评估这些患者最早激动部位附近及心房其余部位的电图碎裂情况。
对13例接受导管消融的FAT患者（年龄48±17岁）进行了研究。使用CARTO系统进行标测。根据最早激动部位周围区域及心房其余部位的负向波数量评估电图碎裂情况。还研究了单极和双极峰 - 峰电压以及双极电图持续时间。所有患者均成功进行了射频消融。与心房其余部位相比，最早激动部位周围区域且在最初15毫秒内激动的区域存在更高程度的电图碎裂（双极电图出现多个负向波的发生率：88% 对79%，P < 0.0001；单极电图出现多个负向波的发生率：56% 对43%，P = 0.0001）。在最初15毫秒内激动的区域，其峰 - 峰电压低于心房其余部位（双极电压：1.33±0.99 mV对1.61±1.11 mV，P < 0.001；单极电压：1.75±0.92 mV对1.95±1.11 mV，P = 0.0188）。双极电图持续时间无显著差异。在最初15毫秒内激动的区域，从周边到最早激动部位，电图碎裂程度逐渐增加（双极电图出现多个负向波的发生率从82%逐渐增加至100%，单极电图出现多个负向波的发生率从56%增加至90%），同时峰 - 峰电压逐渐降低（双极电压从1.47±1.06 mV逐渐降低至0.89±0.54 mV，P < 0.0001；单极电压从1.89±0.94 mV逐渐降低至1.30±0.63 mV，P < 0.0001）。在最初15毫秒内激动的区域还观察到不规则、间距紧密的等时线。该区域面积为4.88±3.59 cm²。
与心房其余部位相比，心动过速起源部位周围相对较宽的区域存在电图碎裂增加的情况。此外，该区域电活动不均一，电图碎裂程度逐渐增加而电图电压朝着最早激动部位逐渐降低这一事实表明了这一点。这些发现提示，具有逐渐变化电生理特性的非离散心房区域可能是FAT的基质基础。
