Feld Gregory K, Yao Biguang
Department of Medicine, Division of Cardiology, Cardiac Electrophysiology Program, School of Medicine, University of California, San Diego, 9444 Medical Center Dr., La Jolla, CA, 92037, USA,
J Interv Card Electrophysiol. 2014 Jan;39(1):37-44. doi: 10.1007/s10840-013-9847-x. Epub 2013 Nov 29.
Catheter ablation of atrial flutter and fibrillation (AFL and AF) has typically been performed with radiofrequency energy. Cryoablation has recently been used for AF and AFL, but its success has been limited by the nadir temperature achievable using nitrous oxide as a refrigerant. In this study, a novel approach allowing for use of a liquid refrigerant capable of achieving lower nadir temperatures was tested in a canine model with cavo-tricuspid isthmus (CTI) and left atrial (LA) ablation.
In six dogs, under general anesthesia, standard catheters were placed in the coronary sinus and right ventricular apex, and the CryoMedix cryoablation catheter (CAC) in the right (CTI) and left atrium (for ablation, across the LA roof, mitral isthmus, and LA septum). Double-freezes up to 2 min each were performed, with a 30-s thaw cycle between freezes. Ablated areas were subsequently grossly inspected and photographed and tissues fixed in formalin for histologic analysis to determine if the lesions were contiguous and transmural. In all animals, long linear (from 4-8 cm) transmural atrial lesions were observed on gross and histological examination in the left atrial roof, septum and mitral isthmus, and across the cavo-trisucpid isthmus. In all animals, bi-directional cavo-tricuspid isthmus block was observed after ablation, during pacing from the coronary sinus ostium and low lateral right atrium, respectively. Up to 50% thickness lesions were observed in the right ventricle below the tricuspid valve in all animals. There were no acute complications noted in any animals.
The CAC system produces extremely negative freezing temperatures, significantly lower than those reported for nitrous oxide based systems. The CTI was easily ablated with the CAC system, producing bi-directional conduction block, suggesting a potential role for the system in the treatment of isthmus-dependent atrial flutter. Transmural LA lesions were also produced with the CAC system, suggesting a potential role in treating AF.
心房扑动和颤动（AFL和AF）的导管消融通常使用射频能量进行。冷冻消融最近已用于AF和AFL，但其成功率受到使用一氧化二氮作为制冷剂可达到的最低温度的限制。在本研究中，在犬类模型中测试了一种允许使用能够实现更低最低温度的液体制冷剂的新方法，该模型用于三尖瓣峡部（CTI）和左心房（LA）消融。
在6只犬中，在全身麻醉下，将标准导管置于冠状窦和右心室心尖，将CryoMedix冷冻消融导管（CAC）置于右心房（用于CTI消融）和左心房（用于跨越左心房顶部、二尖瓣峡部和左心房隔膜进行消融）。每次进行长达2分钟的双重冷冻，两次冷冻之间有30秒的解冻周期。随后对消融区域进行大体检查和拍照，并将组织固定在福尔马林中进行组织学分析，以确定病变是否连续且透壁。在所有动物中，在左心房顶部、隔膜、二尖瓣峡部以及三尖瓣峡部均观察到了长的线性（4 - 8厘米）透壁心房病变，在大体和组织学检查中均如此。在所有动物中，分别从冠状窦口和右心房低位外侧起搏时，消融后均观察到双向三尖瓣峡部阻滞。在所有动物中，在三尖瓣下方的右心室中观察到高达50%厚度的病变。所有动物均未出现急性并发症。
CAC系统产生极低的冷冻温度，显著低于基于一氧化二氮的系统所报告的温度。使用CAC系统可轻松消融CTI，产生双向传导阻滞，表明该系统在治疗峡部依赖性心房扑动中具有潜在作用。CAC系统还产生了透壁的左心房病变，表明在治疗AF方面具有潜在作用。
