Catheter ablation of posteroseptal accessory pathways through the coronary sinus by means of direct current electrical shock is an accepted technique for the treatment of drugresistant patients of the Wolff-Parkinson-White syndrome. Morady F., Scheinman MM, Winston SA, et al; efficacy and Safety of Transcatheter Ablation of Posteroseptal Accessory Pathways--Circulation 72:170, 1985. The Wolff-Parkinson-White syndrome is frequently associated with rapid supraventricular arrhythmias that are related to the presence of accessory atrioventricular connections, which are usually in close contiguity to the coronary sinus. These rhythm disturbances are usually symptomatic and may be life threatening in a subset of patients. Klein GJ, Bashore TM, Sellers TD, et al: Ventricular Fibrillation in the Wolff-Parkinson-White Syndrome. N. Engl. J. Med. 01:1080, 1979. Drug therapy has been effective for suppressing or controlling many of these arrhythmias. With many patients, surgery is becoming the treatment of choice. Prystowsky EN, Pressley JC, Gallagher JJ, et al: The Quality of Life and Arrhythmia Status After Surgery for Wolff-Parkinson-White Syndrome: an 18 years perspective. JACC 9:100A, 1987. The possibility of avoiding surgery by achieving destruction of accessory pathways with ablative techniques represents a major breakthrough in the treatment of the disease. Presently, available ablation techniques involving the coronary sinus are limited to accessory pathways located in the posteroseptal area. The ability to safely and effectively ablate left free wall accessory atrioventricular connections (the most prevalent variety) using laser energy delivered percutaneously via a catheter would represent a significant advance in the management of this disease.
The term "ablative techniques" refers to the use of physical agents capable of modifying conduction in a restricted area of the myocardium for treating or preventing cardiac arrhythmias without losing the structural integrity of the tissue. Fontaine G, Scheinman MM: Ablation in Cardiac Arrhythmias. Futura Publishing Company, Inc., Mount Kisco, N.Y., 1987. There have been several reports of a therapeutic application of intraoperative ablative techniques to sever the normal atrioventricular conduction system. Gianelli S, Ayers SM, Gomprecht RF, et al: Therapeutic Surgical Division of the Human Conduction System. JAMA 199:155, 1968. Slama R., Blondeau P, Aigueperse J, et al: Creation Chirurgicale d'un Bloc Auriculoventriculaire et implantation d'un Stimulateur daus deux cas de Troubles du Rythme Irreductibles. Arch. Med Geur Vaisseaux 60:406, 1967. Other reports have observed the effect of ablation on other conductive systems. Cobb FR, Blumenschein DF, Sealy WC, et al: Successful Surgical Interruption of the Bundle of Kent in a Patient with Wolff-Parkinson-White Syndrome. Circulation 38:1018, 1968. Vedel J, Frank R, Fontaine G, et al: bloc Avriculoventriculaire Intrahisien Definitif Induit au Cours D'une Exploration Endoventriculaire Droit. Arch Med Coeur Vaisseaux 72:107, 1979. Scheinman MM, Morady F, Hess D, et al: Catheter-induced Ablation of the Atrioventricular Junction to Control Refractory Supraventricular Arrhythmias. JAMA 248:851,1982. Gallagher JJ, Svenson RH, Kasell JU, et al: Catheter Technique for Closed-Chest Ablation of the Atrioventricular Conduction System. A Therapeutic Alternative for the Treatment of Refractory Supraventricular Tachycardia. N Eng J Med 306:194, 1982.
It has been suggested that the anatomic relationship of the close proximity of the atrioventricular accessory pathways through subepicardial fat of the atrioventricular groove in close proximity to the coronary sinus may be used to create localized lesions from the coronary sinus using different energy sources, such as direct current electrical shock or radio frequency in an effort to ablate the anomulous atrioventricular connections. Morady F, Scheinman MM: Transvenous Catheter Ablation of A Posteroseptal Accessory Pathway in a Patient with the Wolff-Parkinson-White Syndrome. N. Eng J Med 310:705, 1984. Morady first described the use of this transvenous technique using high energy direct electrical shock. In patients with posteroseptal accessory pathways, this technique has gained increasing popularity as an appealing alternative to surgery due to its high success rate and low incidence of complications. Morady, F., Scheinman, M.M.: Catheter Ablation of Accessory Pathways, Scheiman, M.M. (Ed.): Catheter Ablation of Cardiac Arrhythmias, Martinez Pub. Nighoff Publishing, Boston, pp.163-164. However, a much lower success rate has been achieved for left free wall accessory pathways where the rate of complications of high energy electrical shocks is very high. Fisher JD, Brodman R, Kim SG, Matos JA, Brodman E, Wallerson D, Waspe LE: Attempted Non-Surgical Electrical Ablation of Accessory Pathways via the Coronary Sinus in the Wolff-Parkinson-White Syndrome. JACC 4:685, 1984. This difference is due to the anatomic variations in susceptibility to barotrauma secondary to high energy electrical current shocks. Attempts to reduce the electrical energy to prevent complications have proved to be ineffective for ablations of left sided pathways. Fisher et al, supra.
Radiofrequency current has been proposed as an alternative energy source for catheter ablations. Huang SK, Graham AR, Bharati S, Lee MA, Gorman G, Lev M: Short and Long Term Effects of Transcatheter Ablation of the Coronary Sinus by Radiofrequency Energy. Circulation 78:416,1988. In this technique, current is delivered at a low power during longer periods of time to achieve tissue desiccations. This technique is relatively free of complications, but appears to have a lower success rate than direct current electrical shocks in the few clinical studies that have been published. Borggrefe M, Budde T, Martinez-Rubio A, Hindricks G, Haverkamp W, Gulker H, Breithardt G: Radiofrequency Catheter Ablation for Drug-Refractory Supraventricular Tachycardia. Circulation 78, II:305, 1988.
Studies have shown that the use of the ND:YAG laser provides the best available laser wavelength to achieve subsurface penetration and thermocoagulation of tissue. McCord RC, Weinberg W, Gorisch W, et al: Thermal Effects of Laser Irradiated Biology Tissue. In: Proceedings, Symposium In Laser in Medicine and Biology. GSF-Berichte, BPT 5, Neuherberg, 1977. Further, unlike other laser delivery systems, the ND:YAG laser balloon catheter distributes energy to a significant area of the coronary sinus thereby resolving the problem of targeting an otherwise narrow laser beam. The ND:YAG laser balloon catheter has been developed for percutaneous transluminal coronary angioplasty restenosis prevention. Spears JR: Percutaneous Transluminal Coronary Angioplasty Restenosis: Potential Prevention WIth Laser Balloon Angioplasty. Am J Cardiol 60:61B, 1987.
The present invention provides means for ablating electrically conductive tissue by laser photocoagulation. It further provides means for pacing and recording thereby allowing the localization of the accessory pathways to be ablated. This features, in combination with a novel mapping method and apparatus, provide an improved means for ablation of cardiac electrically conductive tissue by laser photocoagulation. More specifically, the present invention provides the means for more precise and effective catheter ablation of all left sided accessory pathways thereby providing a treatment for drug resistant patients having the Wolff-Parkinson-White syndrome.