Radiofrequency ablation procedures

FIGURE 6-2. Algorithm for the treatment of acute (top portion) paroxysmal supraventricular tachycardia and chronic prevention of recurrences (bottom portion). Note For empiric bridge therapy prior to radiofrequency ablation procedures, calcium channel blockers (or other atrioventricular [AV] nodal blockers) should not be used if the patient has AV reentry with an accessory pathway. (AAD, antiarrhythmic drugs AF, atrial fibrillation AP, accessory pathway AVN, atrioventricular nodal AVNRT, atrioventricular nodal reentrant tachycardia AVRT, atrioventricular reentrant tachycardia DCC, direct-current cardioversion ECG, electrocardiographic monitoring EPS, electrophysiologic studies PRN, as needed VT, ventricular tachycardia.)... 

Radiofrequency catheter ablation Procedure during which radiofrequency energy is delivered through a catheter positioned at the atrioventricular node of the heart for the purpose of destroying one pathway of a reentrant circuit. 

The widespread adoption of partial nephrectomy procedures and the introduction of various forms of ablative treatment (cryoablation and radiofrequency ablation) have brought new challenges to the pathologist in terms of the need to render a diagnosis of RCC on small-needle biopsy or during intraoperative consultation. Additionally, the introduction of specihc forms of targeted systemic therapy to certain classes of RCC has further emphasized the need for proper classihcation of RCC on needle biopsy material. Therefore the recent rise in interest in the utilization of ancillary techniques for the diagnosis of RCC comes as no surprise. 

Fig. 1.2a-c. A multimodality fusion imaging system (Virtual Navigator System, Esaote SpA, Genoa, ltaly)-real-time registration and fusion of pre-procedure CT volume images with intraprocedure US-used for a percutaneous radiofrequency ablation of an hepatocellular carcinoma targeting of the lesion (a), needle placement (b) and evaluation of the ablation zone... 

FDG-PET and FDG-PET-CT can be of benefit in interventional radiological procedures (Fig. 33.10). Compared with CT alone, PET and PET-CT have been found of higher accuracy when assessing the liver for residual disease after radiofrequency ablation (RFA) of liver metastases (Barker et al. 2005). However, a substantial number of false-negative cases caused by very small tumor residuals must be kept in mind. These small tumor residuals, not visible on CT or PET, lead to early tumor recurrence and require a close followup of patients (Veit et al. 2006). Other authors report promising results when following-up patients with liver metastases undergoing therapy with application of microspheres (Lewandowski et al. 2005). 

Recently a significant shift from PEI to radiofrequency ablation (RFA) procedures has been seen, reflected by the respective literature (Fig. 8.1). Fewer RFA treatment sessions are needed compared to PEI to obtain the same response, which, together with a superior local control rate, makes RFA the... 

The indications and contraindications for laser ablation, and the main complications and methods of follow-up are the same as for radiofrequency ablation and microwave coagulation. The procedures are usually guided with CT or ultrasound although MR is sometimes used as well. By inserting up to eight fibres simultaneously it is possible to achieve confluent necrosis of 6-7 cm in diameter. The ultimate burn size is governed by the tumour vascularity and by the vasodilatory response of surrounding normal liver parenchyma. 

Within the last decade thermal ablations have been developed and clinically improved. Different technologies have been evaluated like magnetic resonance-guided laser-induced thermotherapy (MR-guided LITT), radiofrequency ablation (RF), microwave and cryotherapy. For this reason, there has been great interest in further developments of interstitial procedures such as laser coagulation or radiofrequency ablation over the last few years. 

Radiofrequency thermal ablation (RFTA) S. Rossi et al. (1990, 1993) were the first to introduce this procedure. Under analgosedation and local anaesthesia, an expandable, cooled-tip needle electrode is inserted per-cutaneously into the tumour with the help of US, CT or MR guidance. There are various types of probes with some differences. Due to high-frequency alternating current (480-500 kHz), the tumour tissue is gradually heated (up to max. 105 °C). A necrosis voume of 4(-5) cm in diameter can be achieved. An indication is given for 1-3 foci, each with a maximum size of 5 cm in diameter. This also applies to compromised liver func-... 

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