Intraoperative Ablation Research Articles

Curative treatment of atrial fibrillation 2000: percutaneous catheter ablation techniques and intraoperative ablation with minimally invasive techniques

Experimental and clinical mapping studies have indicated that the initiation of atrial fibrillation has to be differentiated from the perpetuation. Curative treatment of atrial fibrillation is one of the main challenges of today's electrophysiology, and the trigger as well as the substrate have recently been targeted.

Antiarrhythmic surgery for treatment of atrial fibrillation--new concepts.

Curative treatment of atrial fibrillation is one of the main challenges of todays electrophysiology. The ideal treatment strategy should be effective, safe, and easy to apply to allow a widespread use. In addition, curative treatment should not only aim on the restoration of sinus rhythm but also restore mechanical atrial function to improve hemodynamics thereby avoiding anticoagulation. With respect to percutaneous catheter ablation no treatment concept with proven efficiency to cure chronic permanent atrial fibrillation is currently available. Surgical techniques such as the Corridor operation and the left atrial isolation procedure have been shown to effectively store sinus rhythm but these procedures do not restore biatrial transport function. Cox's Maze procedure is highly effective, however, it is an extensive and very time consuming technique which precludes the widespread application of this operation. Thus, new intraoperative treatment concepts are currently under intense clinical investigation. Most new concepts aim on the application of contiguous radiofrequency-induced lesion lines in the atria. Some of the new treatment strategies are based on the replacement of the surgical incisions of the Maze procedure using inrtraoperative radiofrequency coagulation thereby preventing functional determined reentrant circuits. Other new concepts aim on the induction of contiguous atrial lesion lines to eliminate anatomical determined atrial reentrant circuits. The main advantage of these new concepts when compared to the Maze procedure is a significantly shorter treatment time of approximately 20 minutes. In addition, some treatment strategies can also be applied in conjunction with minimally invasive cardiac surgery. The initial results reported with application of new treatment concepts indicate that approximately 60-80% of patients operated on can be cured from atrial fibrillation. Randomised studies with these new treatment strategies are necessary to validate the results and to outline which treatment concept may prove superior to others. Based on the progress made, it can be expected that intraoperative ablation of chronic permanent atrial fibrillation will become an important curative treatment strategy.

A new contact probe for intraoperative laser ablation.

Several clinical factors decrease the accuracy of intraoperative laser ablation. The distance to the target, the irradiation angle, and the media are reported among these factors. We developed a new laser probe to resolve these problems. This probe has a hollow conical tube with a tip covered by a thin film. Zero-degree centigrade saline was fed into this probe. Results from using the new probe were compared with those from the conventional noncontact irradiation method with cooling by sprinkled cooling water. In beating canine hearts, ventricles were irradiated with neodymium:yttrium aluminum garnet (Nd:YAG) lasers at 50-200 J/mm2. There was no difference in the mean volume of irradiated tissue between the new and the noncontact method. However, the distribution of volume values in the new method was smaller than that in the noncontact method (P < 0.05). In conclusion, results obtained indicate that this new probe could perform more accurate intraoperative ablation than the conventional method. Problems of stabilizing the distance to the target, the irradiation angle, and the media were resolved.

Current Status of Lasers for Arrhythmia Ablation

Current Status of Lasers for Arrhythmia Ablation. Wavelength specific effects and mode of laser operation allow either photocoagulation or tissue removal as a means of approaching arrhythmia ablation. Successful intraoperative ablation of ventricular tachycardias has been performed with the Nd: YAG laser (photocoagulation) and argon laser (tissue vaporization). The argon laser has been used intraoperatively for transection of accessory pathways. Experimental studies indicate a strong theoretical potential for Nd:YAG laser catheter ablation of ventricular tachycardia. Laser energy has been used experimentally to evaluate the possibility of AV junctional ablation/modification and accessory pathway ablation. Adaption of laser energy to effective catheter systems for arrhythmia ablation requires solutions to problems inherent in all catheter systems and some unique to laser energy. (J Cardiovasc Electrophysiol, Vol. 3, pp. 345–353, August 1992)

術中アブレーションにおけるレーザーエネルギーと高周波エネルギーとの比較

術中アブレーションにおけるレーザーエネルギーと高周波エネルギーとの比較

Hypothesis Testing as an Approach to the Analysis of Complex Tachycardias-an Illustrative Case of a Preexcitation Variant

The correct elucidation of the electrophysiological substrate and mechanism(s) responsible for a complex arrhythmia requires a systematic approach to the analysis of the electrophysiological data. One approach calls for the formulation of a set of hypotheses that could explain the data obtained during the study. The hypotheses are then tested for compatibility with phenomena observed and the one that agrees with the majority of the findings would represent the most tenable explanation. We present the case of a young girl with a wide QRS complex tachycardia and a history of ventricular preexcitation that illustrates this approach. The complexities were resolved only after intraoperative analysis and surgical ablation of a right-sided accessory pathway with decremental properties, and provides further insight into our understanding of the nodoventricular Mahaim fiber.

Argon laser ablation or modification of the atrioventricular conduction system in refractory supraventricular tachycardia

Management of drug-refractory supraventricular tachycardia has been greatly facilitated by several nonpharmacologic therapeutic options. These options include catheter or surgical ablation of the arrhythmogenic substrate or the use of antitachycardia pacemakers. Catheter ablation is performed for interruption or modification of normal or abnormal atrioventricular (AV) conduction using direct current shocks or radiofrequency energy. 1 Intraoperative ablation of these conduction pathways is now only performed in the following cases: in symptomatic patients who have either failed catheter ablation; concomitantly with cardiac surgery for another indication; or in place of catheter ablation in specific conditions, for example, preexcitation syndromes. Implantation of antitachycardia devices is usually restricted to a few highly selected patients. Experimental studies have suggested that argon laser ablation of the specialized AV conduction system or accessory pathways is feasible. 2,3 Since 1986, we have used catheter delivery of argon laser energy for intraoperative ablation of malignant supraventricular and ventricular tachycardia. 4–6 We have previously reported its use in supraventricular tachycardia associated with the Wolff-Parkinson-White syndrome. 5,7 In this study, we report our initial clinical experience with normothermic argon laser catheter ablation of the specialized AV conduction system and examine its clinical electrophysiologic effects.