Electrosurgery: principles and safety issues.

The use of monopolar electrosurgical energy has been the "gold standard" for the past 50 years. It has diverse capabilities, such as fulguration, precise vaporization, and coaptation of large vessels. Technologic advances in performance and safety have positioned this device as a useful tool in a surgeon's armamentarium. The adaptation of active electrode monitoring for stray energy as a result of insulation failure or capacitive coupling and the use of completely metal trocar cannulas will increase the confidence of the surgeon and the safety of his/ her patient. It is the author's opinion that its use will prove itself in laparoscopy. As with any surgical tool or energy source, education and skill are required. This introduction on the principal of the biophysics of electrical energy on tissue and the safety consideration is a start to further one's understanding of this surgical tool.

Transcatheter desiccation of the canine left ventricle using radiofrequency energy: a pilot study.

Catheter ablation of cardiac tissue by means of direct-current electrical energy is associated with several complications. We assessed the efficacy and safety of closed-chest catheter desiccation of the left ventricular myocardium with microbipolar radiofrequency (RF) energy (750 kHz) in five dogs. The unipolar configuration was used with RF energy delivered between the tip electrode of a standard No. 7F tripolar catheter in the left ventricle and an external patch electrode on the left lateral chest wall. A single application with different RF energy settings (100 J, 200 J, and 300 J) was delivered to three individual endocardial sites of the left ventricle. Ventricular tachycardia or fibrillation was not observed during energy application and 24 hours after ablation, as assessed by a Holter recording. There was no damage to the electrode catheter. Dogs were killed on the fifth day. Pathology showed well-delineated ovoid or round-shaped coagulation necrosis at the ablation sites. Microscopic findings consisted of circumscribed areas of necrosis surrounded by a zone of fibroblastic and mononuclear proliferation. In conclusion, catheter ablation of the ventricular myocardium with RF energy is an apparently safe procedure and can effectively produce discrete areas of injury without destruction of surrounding uninvolved myocardium. This method offers potential clinical utility for catheter ablation of refractory sustained ventricular tachycardia.

Closed chest catheter desiccation of the atrioventricular junction using radiofrequency energy--a new method of catheter ablation.

Closed chest catheter ablation of the atrioventricular (AV) junction has been performed with direct current or laser energy. The effect of 750 kHz radiofrequency energy on ablation of the AV junction was evaluated in 13 dogs. The radiofrequency energy was generated from an electrosurgical generator in the bipolar mode. The radiofrequency output was delivered between two distal electrodes (bipolar ablation) in eight dogs, and between the distal electrode and an external patch electrode (unipolar ablation) in another five dogs at varying power (watts) but with a constant pulse duration of 10 seconds. Complete AV block was achieved in 11 dogs and second degree AV block in 2. During the 4 to 7 day follow-up period, complete AV block persisted in 9 of the 11 dogs with initial complete heart block. The other two had return of AV conduction; one had persistent 2:1 AV block and the other had persistent first degree AV block. Of the two dogs with initial second degree AV block, one developed complete AV block, the other had resumption of 1:1 AV conduction with a normal PR interval. Energy was delivered in 1 to 13 applications per dog. One hundred to 700 J per application was delivered with bipolar ablation and 10 to 100 J with unipolar ablation. There was no damage to the catheter unless the catheter was repeatedly used in excess of 1,500 J of total energy. Ventricular arrhythmias were not observed. Pathologic examination showed well delineated coagulation necrosis at the AV junction without surrounding hemorrhage or mural thrombus. Microscopic findings consisted of necrosis with cell infiltration in the periphery of necrosis. Most injuries involved the AV node, the approaches to the AV node and the penetrating bundle. In conclusion, catheter ablation of the AV junction with radiofrequency energy is safe. It can effectively induce discrete areas of necrosis and produce various degrees of AV block. In addition, ablation by radiofrequency energy has distinct advantages as compared with catheter ablation with direct current or laser energy.