Surgical technique and results

Surgery for Ventricular Tachycardia

The treatment of drug-refractory chronic ventricular tachycardia (VT) has undergone a revolution over the last 50 years. We now have automatic implantable cardioverter defibrillator therapy with pace-terminating capabilities, and catheter ablation of VT has refined mapping and improved methods of lesion generation. Between 1980 and 1993, Houston Methodist Hospital became a leader in the diagnosis and surgical ablation of VT and other arrhythmias. This is a brief account of that period and some of the experiences and lessons that have led to significant advances used today.

Cryothermal ablation: mechanism of tissue injury and current experience in the treatment of tachyarrhythmias

Cryosurgery has been an integral part of the surgical management of cardiac arrhythmias since the late 1970s. With the recent development of intravenous cryocatheters, the use of cryothermy in the treatment of cardiac arrhythmias will increase in the near future. The following discussion includes a detailed consideration of the mode of tissue injury associated with cryothermy and a comprehensive review of cryosurgery in the management of a variety of cardiac arrhythmias. Cryosurgical management of supraventricular and ventricular tachycardias has proven to be both safe and effective. Cryothermal tissue injury is distinguished from hyperthermic injury by the preservation of basic underlying tissue architecture and minimal thrombus formation. Such differences will be particularly important in settings requiring extensive lesion formation, such as catheter-based maze procedures for the treatment of atrial fibrillation.

Reflections on definitive surgical treatment of postinfarction ventricular tachycardia

The past 15 years have witnessed a substantial commitment to the understanding and surgical cure of postinfarction ventricular tachycardia, and the results of treatment have steadily improved. However, outside influences have had a negative impact on the use of this modality. With the widespread availability of implantable defibrillators, this has become an attractive alternative therapy to the sometimes difficult definitive surgical treatment. Meanwhile, early thrombolytic therapy for the management of evolving myocardial infarctions has been found to create a postinfarction electrical substrate that does not appear to be arrhythmogenic. As a result, clinical efforts to develop and refine definitive ventricular tachycardia surgical treatments have all but ceased. The intent of this article is to review the events that took place in this apparently transient era.

Argon beam coagulation compared with cryoablation of ventricular subendocardium

The Argon Beam Coagulator uses radiofrequency energy to excite argon gas that may be used for ventricular ablation. The effects of power level and number of applications of the Argon Beam Coagulator were compared wtih cryothermia. Ten mongrel dogs underwent cardiac extirpation. The endocardial surfaces of 5 hearts were used for the creation of lesions using the Argon Beam Coagulator at five power levels with either one or two applications. Five hearts were used for endocardial and epicardial lesions using cryothermia (15-mm-diameter probe at -70 degrees C) for 1, 2, 3, or 4 minutes. The Argon Beam Coagulator lesions showed an increase in depth with increasing power levels (2.25 +/- 1.05 mm at 50 W to 6.64 +/- 0.75 mm at 150 W) and number of applications (maximum depth of 6.64 +/- 0.75 mm with one application, 11.2 +/- 1.1 mm with two applications). Cryothermia lesions were similar in depth regardless of duration or site of application (range, 6.1 to 10.2 mm). Both techniques resulted in homogeneous and well-demarcated lesions. These data show that the Argon Beam Coagulator results in discrete endocardial lesions, which may be created quickly and reproducibly. This may be a useful alternative for the operative ablation of endocardial scar in the treatment of ventricular tachycardia.

Geometrically accurate transaortic mapping of left ventricular endocardial activation during surgery

A device was developed for mapping left ventricular endocardial activation through the aortic valve during surgery. It uses an exploring electrode at the tip of a hand-held probe that is mounted on a mechanical arm with six joints whose movements are digitized by a computer while the position of the probe tip is calculated continuously. The probe is inserted by the surgeon into the left ventricle retrogradely through the aortic valve after the patient is on total cardiopulmonary bypass, the aorta has been opened and the coronary arteries cannulated. The electrode position relative to the aortic valve and left ventricular apex is displayed continuously on a computer screen. When electrograms are recorded from the probe, their positions are displayed on the screen relative to a stylized grid of the left ventricular endocardial surface and are color-coded to indicate the activation sequence. In a patient with nonischemic ventricular tachycardia, the arrhythmia was successfully mapped and cryoablated with use of the device. The device will be developed so that a cryoprobe can be substituted for the exploring electrode and positioned at the source of activation determined by the map.