Kodoth Vivek, Castro Noel C, Glover Ben M, Anderson Jim M, Escalona Omar J, Lau Ernest, Manoharan Ganesh
The Heart Centre, Royal Victoria Hospital, Belfast, Northern Ireland.
J Electrocardiol. 2011 Nov-Dec;44(6):689-93. doi: 10.1016/j.jelectrocard.2011.08.008.
A novel atrial defibrillator was developed at the Royal Victoria Hospital in collaboration with the Nanotechnology and Integrated Bio-Engineering Centre, University of Ulster. This device is powered by an external pulse of radiofrequency energy and designed to cardiovert using low-tilt monophasic waveform (LTMW) and low-tilt biphasic waveform (LTBW), 12 milliseconds pulse width. This study compared the safety and efficacy of LTMW with LTBW for transvenous cardioversion of atrial fibrillation (AF).
Patients were anticoagulated with warfarin to maintain International Normalized Ratio between 2 and 3 for 4 weeks prior cardioversion. Warfarin international normalized ratio level was maintained in between 2 and 3 for 4 weeks prior cardioversion. St Jude's defibrillating catheter was positioned in the distal coronary sinus and right atrium and connected to the defibrillator via a junction box. After a test shock using a dummy load, the patient was cardioverted in a step-up progression from 50 to 300 V. Shock success was defined as return of sinus rhythm for 30 seconds or more. If cardioversion was unsuccessful at peak voltage, the patient was crossed over to the other arm of the waveform type and cardioverted at peak voltage.
Thirty patients were randomized equally to LTBW and LTMW (15 each). Seven out of 15 patients (46%) cardioverted to sinus rhythm with LTBW, and 1 (6%) of 15, with LTMW (P = .035). Including crossover patients, 14 patients (46%) converted to sinus rhythm. After crossover, 4 patients were cardioverted with LTBW and 2 with LTMW. Overall mean voltage, current, and energy used for cardioversion were 270.53 ± 35.96 V, 3.68 ± 0.80 A, and 9.12 ± 3.73 J, respectively, and intracardiac impedance was 70.82 ± 13.46 Ω. For patients who were successfully cardioverted, mean voltage, current, energy, and intracardiac impedance were 268.28 ± 42.41 V, 3.52 ± 0.63 A, 8.51 ± 3.16 J, and 73.92 ± 12.01 Ω. There were no major adverse complications during the study. Cardiac markers measured postcardioversion were unremarkable.
Low-tilt biphasic waveform was more efficacious for low-energy transvenous cardioversion of AF. A significant proportion of patients were successfully cardioverted to sinus rhythm with low energy. Radiofrequency-powered defibrillation can be safely used for transvenous cardioversion of AF.
皇家维多利亚医院与阿尔斯特大学纳米技术与综合生物工程中心合作研发了一种新型心房除颤器。该设备由外部射频能量脉冲供电，设计用于使用低倾斜单相波形（LTMW）和低倾斜双相波形（LTBW）、12毫秒脉冲宽度进行心脏复律。本研究比较了LTMW与LTBW用于经静脉心脏复律房颤（AF）的安全性和有效性。
患者在心脏复律前4周用华法林抗凝，使国际标准化比值维持在2至3之间。在心脏复律前4周，华法林国际标准化比值水平维持在2至3之间。圣犹达除颤导管置于远端冠状窦和右心房，并通过接线盒连接到除颤器。在使用模拟负载进行测试电击后，患者以50至300V的递增顺序进行心脏复律。电击成功定义为窦性心律恢复30秒或更长时间。如果在峰值电压时心脏复律不成功，患者交叉至波形类型的另一组，并在峰值电压时进行心脏复律。
30例患者被随机均分为LTBW组和LTMW组（每组15例）。15例LTBW组患者中有7例（46%）恢复为窦性心律，15例LTMW组患者中有1例（6%）恢复为窦性心律（P = 0.035）。包括交叉患者在内，14例患者（46%）恢复为窦性心律。交叉后，4例患者用LTBW复律，2例用LTMW复律。心脏复律的总体平均电压、电流和能量分别为270.53±35.96V、3.68±0.80A和9.12±3.73J，心内阻抗为70.82±13.46Ω。对于成功复律的患者，平均电压、电流、能量和心内阻抗分别为268.28±42.41V、3.52±0.63A、8.51±3.16J和73.92±12.01Ω。研究期间无重大不良并发症。心脏复律后测量的心脏标志物无异常。
低倾斜双相波形在低能量经静脉心脏复律房颤方面更有效。相当一部分患者以低能量成功复律为窦性心律。射频供电除颤可安全用于经静脉心脏复律房颤。
