Olson Matthew D, Phreaner Nicholas, Schuller Joseph L, Nguyen Duy T, Katz David F, Aleong Ryan G, Tzou Wendy S, Sung Raphael, Varosy Paul D, Sauer William H
J Interv Card Electrophysiol. 2013 Nov;38(2):123-9. doi: 10.1007/s10840-013-9824-4.
The efficient delivery of radiofrequency (RF) energy through an endocardial ablation catheter is affected by variable tissue contact due to cardiac motion with myocardial contraction and respiration. In addition, many operators intentionally move an ablation catheter during the delivery of radiofrequency energy when targeting specific arrhythmias that require lines of conduction block such as atrial flutter and atrial fibrillation. We sought to characterize and quantify any effects of catheter movement and intermittent ablation catheter contact on lesion characteristics.
An ex vivo model consisting of recently excised viable bovine myocardium, a circulating saline bath at 37 °C, a submersible load cell, and a deflectable sheath with an ablation catheter was assembled. A stepper motor attached to an ablation catheter apparatus was programmed to simulate linear drag lesions and series of point lesions with variable contact using constant force. Lesion volumes were analyzed using a digital micrometer by measuring depth, max width, depth at max width, and surface width and compared.
The drag lesion was significantly larger than a pointby-point linear lesion using a constant force of 15 g (2,088± 122 mm3 vs. 1,595±121.6; p =0.01) when controlling for RF time and power. For single point lesion assessment, constant contact lesions were significantly larger than lesions created with intermittent contact using the same duration of RF (194± 68 mm3 vs. 112.5±53; p =0.03). There was no significant difference in lesion size between the constant contact at 60 s and 90-s intermittent contact lesions (194±68 mm3 vs.186±69).
In our ex vivo model, externally irrigated radiofrequency catheters produced drag lesion volumes equal to or larger than those created by a point-by-point method.We also found decreased lesion size due to intermittent contact can be overcome by increasing duration of ablation time.
由于心肌收缩和呼吸导致的心脏运动，经心内膜消融导管有效输送射频（RF）能量会受到组织接触变化的影响。此外，在针对需要传导阻滞线的特定心律失常（如心房扑动和心房颤动）进行射频能量输送时，许多操作人员会故意移动消融导管。我们试图描述和量化导管移动和间歇性消融导管接触对病变特征的任何影响。
构建了一个体外模型，该模型由最近切除的活牛心肌、37℃的循环盐水浴、一个潜水式称重传感器以及一个带有消融导管的可偏转鞘管组成。连接到消融导管装置的步进电机被编程为使用恒定力模拟线性拖动损伤和一系列具有可变接触的点状损伤。使用数字千分尺通过测量深度、最大宽度、最大宽度处的深度和表面宽度来分析损伤体积并进行比较。
在控制射频时间和功率时，使用15g恒定力时，拖动损伤明显大于逐点线性损伤（2088±122mm³对1595±121.6；p = 0.01）。对于单点损伤评估，在相同射频持续时间下，恒定接触损伤明显大于间歇性接触产生的损伤（194±68mm³对112.5±53；p = 0.03）。60秒恒定接触损伤和90秒间歇性接触损伤之间的损伤大小没有显著差异（194±68mm³对186±69）。
在我们的体外模型中，外部灌注的射频导管产生的拖动损伤体积等于或大于逐点法产生的损伤体积。我们还发现，通过增加消融时间可以克服因间歇性接触导致的损伤大小减小。
