Percutaneous Ablation Techniques Research Articles

Current limitations of radiofrequency ablation in renal cell carcinoma.

Current limitations of radiofrequency ablation in renal cell carcinoma.

Review article: liver transplantation for HCC. Treatment options on the waiting list.

The most widely adopted criteria to admit and maintain patients with HCC and cirrhosis in the waiting list for liver transplantation are the Milano criteria, consisting in the presence of a single tumour <or=5 cm in diameter or up to three tumours, none exceeding 3 cm in diameter. Since the average time to transplantation has become longer than 10-12 months in most European and American Centers, the exclusion from the list during the waiting period due to increase of the neoplasm over the established criteria is not uncommon at present. It is mandatory, therefore, to seek an effective therapeutic strategy for patients with HCC waiting for transplantation. Surgical resection and eventual subsequent salvage transplantation seems a cost-effective strategy in resectable HCC. In unresectable neoplasms both transarterial chemoembolization and percutaneous ablation techniques are currently used and one or the other are chosen according to individual applicability, limitations and specific risks. However, although positive trends were reported, no definitive evidence has been produced so far about their efficacy in increasing patient's survival and decreasing tumour recurrence rates after transplantation. Adult-to-adult living donor liver transplantation is one possible way to shorten the waiting list, but this strategy involves important ethical implications. At present it appears justified to take it into consideration only if the waiting time for cadaveric OLT is expected to exceed 7 months. A more general and definitive attempt to overcome problems related to long waiting times for patients with HCC and relatively preserved hepatic function has been introduced in the USA very recently and consists in prioritizing patients with HCC. However, the overall efficacy of this approach will be established only in some years.

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.

Intraoperative radiofrequency ablation of chronic atrial fibrillation: a left atrial curative approach by elimination of anatomic "anchor" reentrant circuits.

The percutaneous approach to radiofrequency (RF) catheter ablation for curative treatment of atrial fibrillation (AF) is an investigational technique, and the optimal composition of lesion lines is unknown. We tested an intraoperative RF ablation concept with elimination of left atrial anatomic "anchor" reentrant circuits. In 12 patients with an indication for valve surgery and chronic AF, a right atrial-transseptal approach was chosen for access to the left atrium. AF had been present for 4.3 +/- 3.9 years; the left atria measured 56 +/- 7 mm. Under direct vision, contiguous lesion lines were placed endocardially with temperature-guided RF energy applications for treatment of AF with a specially designed probe. The lesion lines were placed between the mitral annulus and the left lower pulmonary vein, further to the left upper pulmonary vein, from there to the right upper pulmonary vein, and finally to the right lower pulmonary vein. The antiarrhythmic ablation procedure lasted 19 +/- 4 minutes. One patient died postoperatively of low cardiac output. During follow-up of 11 +/- 6 months, chronic AF was ablated successfully in 9 of 11 patients (82%). Six patients were in stable sinus rhythm or intermittent pacemaker rhythm, and three patients were in sinus rhythm with intermittent atypical atrial flutter. Intraoperative RF energy application for induction of contiguous lesion lines is feasible. Elimination of anatomically defined "anchor" reentrant circuits within the left atrium prevented chronic AF in > 80% of the patients treated. Intraoperative validation of lesion line concepts for curative treatment of AF may be transferred to percutaneous ablation techniques.

Parathyroid Localization, Three-Dimensional Modeling, and Percutaneous Ablation Techniques

When available, state of the art noninvasive localization studies should be utilized routinely in previously unexplored patients for localizing parathyroid pathology, even when exceptional surgical experience exists. These studies can both minimize the 3 to 20% incidence of missed pathology and promote an approach of limited neck exploration with consequent lowering of morbidity, complications, and costs. Choice of imaging modalities for localizing these small masses is largely dependent on the level of state of the art of available equipment, the interest and experience of the performing physicians, and the attention to technical detail for each of the modalities at an individual institution. In choosing a single test, CT, and most recently cine CT with three-dimensional modeling, is favored because of higher probability of providing the kinds of information most useful to the surgeon. This includes precise anatomic localization and identification of locations likely to be missed by the surgeon (such as mediastinum, deep neck) and the capability for predicting multiple gland disease, for detecting smaller lesions, and for lower incidence of false-positive results. Ultrasound is attractive because of the low cost and noninvasiveness, and it is particularly sensitive in the thyroid region and upper neck. In difficult cases, CT, cine CT, and ultrasound may be augmented by needle aspiration of fluid for PTH assay. Thallium-technetium scanning and MRI are useful alternatives. In the previously explored patient and in patients with difficult diagnostic problems (such as ectopic adenoma, parathyroid carcinoma), the use of multiple noninvasive studies is strongly recommended, preferably CT (particularly, cine CT with three-dimensional imaging) and isotope scanning or MRI. The concurrence of two or more of these studies has a relatively high predictive value (82 to 88%) for localization. However, highly selective venous catheterization and selective magnification arteriography remain the most accurate modalities in these patients (91 to 95% sensitivity with few false-positive results) and may be combined with interventional radiologic techniques for tumor ablation in selected patients without compromising subsequent surgical alternatives. Stereotactic ablation techniques are in development.