Sapp John L, Cooper Joshua M, Zei Paul, Stevenson William G
Dalhousie University, Queen Elizabeth II Health Sciences Centre, Halifax, Nova Scotia, Canada.
J Cardiovasc Electrophysiol. 2006 Jun;17(6):657-61. doi: 10.1111/j.1540-8167.2006.00439.x.
Radiofrequency (RF) catheter ablation of ventricular tachycardia is sometimes limited by inadequate lesion depth. We report the use of a novel retractable needle-tipped electrode catheter with intramyocardial (IM) saline infusion and IM RF energy delivery to create large myocardial ablation lesions.
The left ventricle was entered via the femoral artery in 6 and 11 anesthetized goats and swine (32-90 kg) with an 8-F electrode catheter with an extendable 27-gauge needle at the tip (modified for RF ablation by making the needle electrically active). The needle was advanced 5-7 mm intramyocardially and 0.9% saline was infused 1 mL/min x 60 seconds prior to, and throughout a 120-second application of RF via the active needle, with power titrated to 12 W for 9 lesions, and 30-40 W for 37 lesions, followed by a 120-second RF application using the 4-mm-tip electrode, with power titrated to achieve a 10-Omega decrease in impedance. Needle/saline lesions were compared to 18 standard 4-mm-tip control lesions (power titrated to < or =50 W, to achieve a 10-Omega impedance decrease or limited to 60 degrees Celsius) and to 17 irrigated 3.5-mm-tip lesions (power titrated to < or =50 W, temperature limited to 50 degrees Celsius, 30 mL/min infusion rate). Lesions were identified in the excised heart, fixed, serially sectioned from the endocardium, and digitally analyzed to calculate volume.
Lesions were homogeneous and had distinct borders. Compared to 4-mm-tip and irrigated-tip lesions, high-power needle/saline lesions were significantly deeper (13 +/- 2 vs 5 +/- 1 and 8 +/- 3 mm, P < 0.001), had significantly larger volumes (1,700 +/- 750 vs 240 +/- 170 and 750 +/- 650 mm(3), P < 0.001), and had larger cross-sectional area at each millimeter depth beyond the 1 mm (P < 0.01).
IM saline infusion and IM RF energy delivery markedly increase RF lesion size as compared to standard RF ablation and is feasible with a percutaneous catheter. This method warrants further investigation because of its potential clinical utility.
室性心动过速的射频（RF）导管消融有时会受到病变深度不足的限制。我们报告了一种新型的可回缩针尖电极导管的应用，该导管可进行心内膜下（IM）盐水灌注和IM射频能量传递，以创建大型心肌消融病变。
在6只和11只麻醉的山羊和猪（体重32 - 90千克）中，通过股动脉将带有可延伸27号针头的8F电极导管插入左心室（通过使针头具有电活性对其进行了射频消融改造）。将针头推进至心内膜下5 - 7毫米，在通过活性针头进行120秒射频施加之前及整个过程中，以1毫升/分钟的速度注入0.9%的盐水60秒，对于9个病变，功率滴定至12瓦，对于37个病变，功率滴定至30 - 40瓦，随后使用4毫米尖端电极进行120秒的射频施加，功率滴定以实现阻抗降低10欧姆。将针头/盐水病变与18个标准的4毫米尖端对照病变（功率滴定至≤50瓦，以实现阻抗降低10欧姆或限制在60摄氏度）以及17个灌注的3.5毫米尖端病变（功率滴定至≤50瓦，温度限制在50摄氏度，灌注速率30毫升/分钟）进行比较。在切除的心脏中识别病变，固定，从心内膜进行连续切片，并进行数字分析以计算体积。
病变均匀且边界清晰。与4毫米尖端和灌注尖端病变相比，高功率针头/盐水病变明显更深（13±2对5±1和8±3毫米，P < 0.001），体积明显更大（1700±750对240±170和750±650立方毫米，P < 0.001），并且在超过1毫米的每个毫米深度处的横截面积更大（P < 0.01）。
与标准射频消融相比，心内膜下盐水灌注和心内膜下射频能量传递显著增加了射频病变大小，并且通过经皮导管是可行的。由于其潜在的临床应用价值，该方法值得进一步研究。
