Cryoablation Research Articles

Percutaneous Tumor Ablation: Microencapsulated Echo-guided Interstitial Chemotherapy Combined with Cryosurgery Increases Necrosis in Prostate Cancer.1

This study aimed at confirming the increased growth inhibition (GI) of human prostate tumors produced by a intentionally palliative combination treatment of cryochemotherapy, i.e., partial cryoablation (CA) followed by intratumor partial chemotherapy with injection of microencapsulated 5-fluorouracil (MCC/5FU) at the ice ball (IB) periphery. We report the local effectiveness of cryochemotherapy compared to chemotherapy only with using multiple injections of MCC/5FU spaced out to maximize cumulative effect of sustained release of 5-fluorouracil (5FU) during a 21-day period. Prostate bioluminescent tumor cells - DU145 Luc+ - were implanted sub-cutaneously and bilaterally in each flank of nude mice. Tumors were treated with: (i) cryoablation alone (CA), causing necrosis in approximately 45% of the tumor volume; (ii) cryo-chemotherapy (CA+MCC/5FU), a combined regimen consisting of partial CA followed immediately and on day 14 by ultrasound assisted, intra-tumor injections (40 mul) of MCC/5FU( 0.81 ng/mm3 of tumor) containing Ethiodol (IPO) an imaging contrast agent, on two opposite sides of the unfrozen part of tumor; (iii) intratumor chemotherapy (MCC/5FU), consisting of three successive intra-tumor injections of microencapsulated 5FU on two opposite sides on Day 0, 4, and 11, and (iv) control series (MM), consisting of a single injection of echogenic microcapsules (mucaps) containing IPO but no 5FU. Tumor growth and viability were followed during a 21-day period with using biometric measurements, bioluminescent imaging (BLI) and ultrasonography (US), and then animals were sacrificed. CA, spared 54.4% of the tumor volume and the IB kill ratio was 0.4 +/-0.9. The maximum tumor volume reduction observed by Day 3 was short-lived as re-growth became significant by Day 6. CA+ MCC/5FU spared 55.6% of the tumor volume and the IB kill ratio was 0.54 +/- 0.12. The viable tumor cells, as measured by BLI remained at preoperative levels. After 11 days CA+ MCC/5FU limited the growth of the partially ablated tumors to only 10.6% of the growth of CA treated tumors (p=0.04). By Day 18 the CA+MCC/5FU had inhibited tumor growth by 78% compared to the CA treated tumors (p=0.05) and after 21 days the growth was inhibited by 71% (p=0.04) compared to more than 650% growth in the MM group and 600% growth in the CA treated group. The two injections of MCC/5FU produced a visible focal necrosis in 55% of the tumors. MCC/5FU proved effective by themselves and reduced the growth of prostate tumor volumes by 51% (p=0.025) compared to MM controls during the 21 days. Focal necrosis was macroscopically visible at the site of 66% of the tumors injected only with MCC/5FU. The BLI clearly showed zones of reduced tumor cell viability at the injection sites. The mean number of bioluminescent (viable) tumor cells, remained below preoperative levels for the first 6 days and then increased at a rate approximately 20% that of the growth of control tumor cells. The chemoablative effects of intentionally limited doses of MCC/5FU injected within the IB margin augment the effects of incomplete cryoablation in this prostate tumor model, with dramatic tumor GI and directionally increased necrosis dimensions compared to CA alone, confirming the results of a previous study. Our results indicate the potential advantages of our combination cryochemotherapy that utilizes different mechanisms to kill tumor cells and retard tumor growth in the region surrounding the IB where tumor cells escape the lethal effects of cryosurgery. The study suggests that cryochemotherapy may become a more predictable technique that could be indicated as an adjuvant or an alternative to palliative therapy of hormone refractory prostate cancer (HRPC).

Differences in Patterns of Care: Reablation and Nephrectomy Rates After Needle Ablative Therapy for Renal Masses Stratified by Medical Specialty

We aimed to study differences in reablation rates, modality utilization, and outcomes after renal tumor cryoablation (CA) and radiofrequency ablation (RFA), stratified by medical specialty. A literature review was performed to identify papers reporting renal RFA and CA results. Patient demographics and clinical and pathological variables were collected, as were ablation success and salvage treatment rates. Interventional radiologists (IR) reported more experience with renal RFA than with CA (31.4% v 11.3% of all reported cases, p < 0.001). However, the majority of renal RFA and CA are performed by urologists. The percutaneous approach was used far more often with RFA than with CA, reflecting this preference by radiologists (80.9% v 23.4%, p < 0.01). The mean tumor size, cancer-specific survival rates, mean follow-up duration, and salvage nephrectomy rates were not statistically different between CA and RFA. Tumor reablation rates were significantly higher for RFA than for CA (7.4% v 0.9%, p = 0.009). RFA reablation rate correlated closely to surgeon specialty, such that 72% of reablations were reported by IR, while only 28% were performed primarily by urologists (p < 0.0001). This was despite IR being primary surgeons in only 31.4% of first tumor ablations. Salvage nephrectomy was performed more after CA than after renal RFA, probably because 89% of CA were done by urologists. There were no reablations in the laparoscopically approached cases. Cancer-specific outcomes after renal tumor CA and RFA are similar. However, RFA has required more reablations to achieve 95% cancer-specific survival rates. IR reported more experience with RFA, and urologists reported more experience with CA. Overall, RFA and CA reablation rates are significantly higher when a percutaneous approach is used and seemed to correlate with surgeon specialty.

Current status of minimally invasive techniques in treatment of pancreatic cancer

Minimally invasive techniques have become one of the research direction of advanced pan-ereatic cancer therapy.The approaches such as high intensity focused ultrasound, radiofrequency ablation, mi-crowave ablation, percutaneous ethanol injection, photodynamic therapy, cryoablation and so on can creat degen-eration and(or) necrosis in different degree of pancreatic cancer tissue, relieve the pain successfully, markedly improve quality of life, prolong survival time and then offer a new therapy for pancreatic cancer patients. Key words: Pancreatic neoplasms; Therapy; Surgery, minimally invasive techniques

Abstract 4105: Increasing Contact Force Increases Lesion Size during Cryo-Ablation

The purpose of this study was to determine the relationship between electrode-tissue (ET) contact force and lesion size during cryo ablation for two cryo electrode lengths in both perpendicular and parallel orientations using the canine thigh muscle preparation. In 3 anesthetized dogs, the skin over the thigh muscle was incised and raised to form a cradle which was superfused with heparinized blood at 37°C. 10F catheters with 6.5 mm and 10 mm (8.5 mm exposed) cryo electrodes (CryoCor) were held perpendicular and parallel to the thigh muscle at 3 ET contact forces: 0 g (1mm above tissue with only ice ball contact); 2)10 –15g (Low Contact); and 30 –35 g (High Contact). Pulsatile blood flow (0.5 m/sec) was directed at the ablation site. Two cryo applications (− 90°C for 2 min) were delivered per dog for each of the 3 contact forces, at parallel and perpendicular orientations, for 6.5 and 10 mm electrodes (total 72 cryo). Temperatures were measured at the electrode and within the tissue at depths of 2, 4 and 6 mm. Lesion size was measured using nitroblue tetrazolium. Lesion depth and diameter increased with increasing ET contact force in both electrode orientations and both electrode sizes ( Fig ). Tissue temperatures (2 mm, 4 mm and 6 mm depths) were significantly lower with ET contact (low and high), compared to no contact (0 g). Compared to 6.5 mm, the 10 mm electrode produced slightly greater lesion diameter in parallel orientation, but did not increase lesion depth. Cryo ablation without ET contact (only ice ball contact) produced little or no lesion. ET contact force facilitates cryo ablation. Ice ball contact alone is insufficient for lesion formation.

Percutaneous cryoablation of prostate cancer guided by rectal ultrasound: A retrospectively analysis of 42 cases

Objective To evaluate the effectiveness and safety of rectal ultrasound-guided agon- hilium percutaneous cryoablation in treatment of patients with median and or late-stage prostate cancer patients. Methods Retrospectively analysis of 42 cases of with stage C and D prostate cancer patients treated by rectal ultrasound-guided argoni TRUS-messured prostate volumes at before and 3, 6,12 months after cryoablation were (59.7± 8.2),(46.9±8.3),(26.2±3.9),(25.9±3.7)mm3, respectively; MFR before and 3, 6,12 months after cryoablation were (10.4±0.8), (14.3±1.2), (18.3±1.3), (18.9±1.3) ml/s, respectively; Compared with before cryoablation, the differences between before and after cryoablation was statistically significant( F = 53.93,747.92,3843.03,respectively, P<0.01). The bPFS rates in 3 months,6 months and 12 months were 95.2% (40/42), 95. 2% (40/42), and 90.5% (38/42), respectively. According to the PSA response, the total effective rate (CR 16 cases, PR 15 cases) at 12 months was 73. 8%, and SD was 16.7% (7/42), PD was 9.5% (4/42). Complications included temporary incontinence 2.4% (1/42), Penile tingling/numbness 2.4% (1/42), pelvic pain 4.9% (2/41) and Scrotum Edema 2.4% (1/42). There was no case with severe complications such as severe infection or urethrorectal fistula, etc. Condusions Rectal ultrasound-guided agon-hilium percutaneous cryoablation showed is a well tolerated and has better early clinical efficacy to the treatment of stage C and D prostate cancer. Key words: Prostatic neoplasms; Cryosurgery; Argon; helium cryoablation; Ultrasonography, Interventional

Acute success and short-term follow-up of catheter ablation of isthmus-dependent atrial flutter; a comparison of 8 mm tip radiofrequency and cryothermy catheters

ObjectivesTo compare the acute success and short-term follow-up of ablation of atrial flutter using 8 mm tip radiofrequency (RF) and cryocatheters.MethodsSixty-two patients with atrial flutter were randomized to RF or cryocatheter (cryo) ablation. Right atrial angiography was performed to assess the isthmus. End point was bidirectional isthmus block on multiple criteria. A pain score was used and the analgesics were recorded. Patients were followed for at least 3 months.ResultsThe acute success rate for RF was 83% vs 69% for cryo (NS). Procedure times were similar (mean 144 ± 48 min for RF, vs 158 ± 49 min for cryo). More applications were given with RF than with cryo (26 ± 17 vs. 18 ± 10, p < 0.05). Fluoroscopy time was longer with RF (29 ± 15 vs. 19 ± 12 min, p < 0.02). Peak CK, CK-MB and CK-MB mass were higher, also after 24 h in the cryo group. Troponin T did not differ. Repeated transient block during application (usually with cryoablation) seemed to predict failure. Cryothermy required significantly less analgesia (p < 0.01), and no use of long sheaths (p < 0.005).The isthmus tended to be longer in the failed procedures (p = 0.117). This was similar for both groups, as was the distribution of anatomic variations. Recurrences and complaints in the successful patients were similar for both groups, with a very low recurrence of atrial flutter after initial success.ConclusionsIn this randomized study there was no statistical difference but a trend to less favorable outcome with 8 mm tip cryocatheters compared to RF catheters for atrial flutter ablation. Cryoablation was associated with less discomfort, fewer applications, shorter fluoroscopy times and similar procedure times. The recurrence rate was very low. Cryotherapy can be considered for atrial flutter ablation under certain circumstances especially when it has been used previously in the same patient, such as in an AF ablation.

Cryoablation for Small Renal Tumors in Older Patients

Incidental detection of solid renal masses during abdominal imaging is increasing in older patients (JW Nov 30 2006). Although these masses often are malignant histologically, many are indolent clinically. A therapeutic option for patients who are poor surgical candidates is cryoablation, in which cryoprobes are inserted …

Cryoablation for Small Renal Masses

Advances in imaging techniques (CT and MRI) and widespread use of imaging especially ultrasound scanning have resulted in a dramatic increase in the detection of small renal masses. While open partial nephrectomy is still the reference standard for the management of these small renal masses, its associated morbidity has encouraged clinicians to exploit the advancements in minimally invasive ablative techniques. The last decade has seen the rapid development of laparoscopic partial nephrectomy and novel ablative techniques such as, radiofrequency ablation (RFA), high-intensity focused ultrasound (HIFU), and cryoablation (CA). In particular, CA for small renal masses has gained popularity as it combines nephron-sparing surgery with a minimally invasive approach. Studies with up to 5-year followup have shown an overall and cancer-specific 5-year survival of 82% and 100%, respectively. This manuscript will focus on the principles and clinical applications of cryoablation of small renal masses, with detailed review of relevant literature.

Observation of influence of treating primary liver cancer with percutaneous targeted argon-helium cryoablation on multiple systems and nursing for such patients

回顾227例(326例次)经皮肝穿刺氩氦刀靶向治疗肝癌治疗过程中对多系统的影响,如:发热、疼痛、皮肤冻伤、恶性呕吐、室性早搏、窦性心动过缓、冷休克、肠梗阻等,分析了各种影响产生的原因,认为术前良好的沟通和指导,术中、术后对病情的密切观察,各种症状的及时处理,及早期的护理干预,是可以减少或减轻对多系统的影响,提高患者的生活质量和生存期的。

Assessment of systemic inflammatory response (SIR) in patients undergoing radiofrequency ablation or partial liver resection for liver tumors

Introduction Local therapies for liver tumors are considered to be safe. However, cryoablation (CA) has been associated with an exaggerated systemic inflammatory response (SIR). Aim of this study was to assess the degree of SIR after radiofrequency ablation (RFA) in comparison with major (MR) or minor (mR) liver resection. Material and methods Thirty-nine patients were treated with RFA ( n = 11), MR ( n = 10) or mR ( n = 18). SIR parameters [white blood count (WBC) and C-reactive protein (CRP)], proinflammatory mediators [IL-6, TNF-α and sPLA2], liver damage parameters [AST/ALT] and platelet counts were determined at different time points. The volume of ablated liver was calculated on the first CT after RFA in order to correlate ablated liver volume with liver enzyme release and SIR. All data are expressed as median values with quartiles [25%, 75%]. Results RFA induced a moderate SIR, as demonstrated by a significant elevation of CRP (77 mg/L vs 3 mg/L), IL-6 (96 pg/ml vs 4 pg/ml) and sPLA2 (41 ng/ml vs 7 ng/ml, p < 0.05). Peak point values of SIR (WBC and CRP at 24 vs 48 h and 48 vs 72 h) and proinflammatory response parameters (24 vs 48 h) occurred earlier after RFA than after mR or MR. Time-to-time comparison revealed even increased levels of CRP (77 mg/L [59, 160]) 24 h after RFA when compared to patients undergoing major or minor resection (50 mg/L [28, 66] and 59 mg/L [24, 91], respectively) and increased levels of IL-6 (67 pg/ml [42, 131]) 4 h after RFA when compared to patients undergoing minor resection (29 pg/ml [20, 55]). Postoperative levels of AST and LDH correlated significantly with the ablated liver volume 1 h after RFA (RC = 0.860 and RC = 0.868, respectively, p < 0.05). Conclusion RFA induced a moderate SIR of the same magnitude as in patients undergoing partial liver resection. None of the patients showed signs of an exaggerated SIR, as has been reported after cryoablation.

Randomized trial comparing cryoablation and external beam radiotherapy for T2C-T3B prostate cancer

The objective was to evaluate the relative efficacy of cryoablation (CRYO) versus external beam radiation (EBRT) for clinically locally advanced prostate cancer in a randomized clinical trial. Patients with histologically proven, clinically staged as T2C, T3A or T3B disease were randomized with 6 months of perioperative hormone therapy to one of the two procedures. Owing largely to a shift in practice to longer term adjuvant hormonal therapy and higher doses of radiation for T3 disease, only 64 out of the planned 150 patients were accrued. Twenty-one of 33 (64%) in the CRYO group and 14 of 31 (45%) in the EBRT-treated group who had met the ASTRO definition of failure were also classified as treatment failure. The mean biochemical disease-free survival (bDFS) was 41 months for the EBRT group compared to 28 months for the CRYO group. The 4-year bDFS for EBRT and CRYO groups were 47 and 13%, respectively. Disease-specific survival (DSS) and overall survival (OS) for both groups were very similar. Serious complications were uncommon in either group. EBRT patients exhibited gastrointestinal (GI) adverse effects more frequently. Taking into account the relative deficiency in numbers and the original trial design, this prospective randomized trial indicated that the results of CRYO were less favorable compared to those of EBRT, and was suboptimal primary therapy in locally advanced prostate cancer.

Tachyarrhythmias in Koch's triangle: to be burned out or to be cool?

Radiofrequency (RF) ablation has proven to be highly effective in the treatment of tachyarrhythmias in Koch’s triangle. Despite this successful approach, several disadvantages can be expected, such as patient discomfort, coagulum formation on the electrode, intralesional haemorrhage, endocardial disruption leading to thrombus formation, steam popping or perforation, some degree of tissue disruption with irreversible damage, and ragged edges, making it potentially arrhythmogenic. More importantly, there is an increased risk for right bundle branch block or inadvertent complete heart block. Therefore, alternative energy sources have been developed, of which cryo ablation seems to be very promising. This energy source has the ability to reversibly demonstrate loss of function with cooling to less negative temperatures (cryo mapping) so that prospective ablation sites can be investigated, before a definitive and irreversible lesion is created. 1 This should lead to less applications and abolish the risk of permanent conduction disturbances. Progressive ice formation at the catheter tip causes adherence to the adjacent tissue, making ablation safe to perform during unstable catheter position or even during tachycardia, without the risk of dislodgement of the catheter at termination of the arrhythmia. The more precise delivery of therapy due to cryo mapping and the creation of smaller lesions both in area and volume, together with the formation of a homogenous fibrosis with a proven preservation of the extracellular matrix and a well demarcated border, makes it potentially less thrombogenic and proarrhythmic. In atrioventricular nodal reentrant tachycardia (AVNRT), it is the only method to target the slow pathway on EP basis, as during cryo mapping programmed atrial stimulation can be performed to determine if the AH jump has disappeared and/or AVNRT is no longer inducible without carrying the risk of dislodgement of the catheter. 2 Of course, extensive clinical investigation is needed to evaluate these theoretical advantages. In this context, four articles have recently been published in this journal concerning cryo ablation in patients with AVNRT. 3–6.

Oncologic outcomes for ablative therapy of kidney cancer

Needle ablative therapies for small incidental renal masses are emerging as alternatives to traditional extirpative surgery. Reasons include their associated decreased morbidity, shorter convalescence, and the ability to avert the higher risk of extirpative surgery in an aging patient population. Cryoablation (CA) and radiofrequency ablation are the two most thoroughly studied needle ablative methods used for renal cancer. High-intensity focused ultrasound has also been studied but with limited published human experience at this time. For both radiofrequency ablation and CA, in vitro experiments, animal studies, and (increasingly) human experience have been published, allowing us to define appropriate candidates for such therapies, their oncologic outcomes, and the potential pitfalls. While long-term data is being collected, the current literature suggests that CA and radiofrequency ablation can be safely performed and can effectively eradicate small renal cancers with cancer-specific survival rates similar to those of traditional surgical options.

Efficacy of Cryoablation in Pediatric Tachycardia

冷冻消融术是继射频消融术后一项新的治疗心律失常的手段,它在某些特殊地带如靠近房室结、希氏束的间隔部位以及腔静脉内病灶,进行消融时较射频导管消融术有更好的精确性、安全性、有效性以及无疼痛的特点,正在引起越来越多的专科医生的重视,尤其在儿科患者对保证其将来的生活质量尤为重要.目前其应用在全球尚处于起步阶段,病例样本少、随访时间短,在实际应用时仍需掌握好指征,但通过多中心的合作研究已初步体现出优越的实用价值。

Efficient loading of dendritic cells following cryo and radiofrequency ablation in combination with immune modulation induces anti-tumour immunity

Dendritic cells (DC) are professional antigen-presenting cells that play a pivotal role in the induction of immunity. Ex vivo-generated, tumour antigen-loaded mature DC are currently exploited as cancer vaccines in clinical studies. However, antigen loading and maturation of DC directly in vivo would greatly facilitate the application of DC-based vaccines. We formerly showed in murine models that radiofrequency-mediated tumour destruction can provide an antigen source for the in vivo induction of anti-tumour immunity, and we explored the role of DC herein. In this paper we evaluate radiofrequency and cryo ablation for their ability to provide an antigen source for DC and compare this with an ex vivo-loaded DC vaccine. The data obtained with model antigens demonstrate that upon tumour destruction by radiofrequency ablation, up to 7% of the total draining lymph node (LN) DC contained antigen, whereas only few DC from the conventional vaccine reached the LN. Interestingly, following cryo ablation the amount of antigen-loaded DC is almost doubled. Analysis of surface markers revealed that both destruction methods were able to induce DC maturation. Finally, we show that in situ tumour ablation can be efficiently combined with immune modulation by anti-CTLA-4 antibodies or regulatory T-cell depletion. These combination treatments protected mice from the outgrowth of tumour challenges, and led to in vivo enhancement of tumour-specific T-cell numbers, which produced more IFN-γ upon activation. Therefore, in situ tumour destruction in combination with immune modulation creates a unique, ‘in situ DC-vaccine’ that is readily applicable in the clinic without prior knowledge of tumour antigens.

One-year follow-up in a prospective, randomized study comparing radiofrequency and cryoablation of arrhythmias in Koch's triangle: clinical symptoms and event recording

To rely solely on clinical symptoms of recurrent palpitations to evaluate the success of interventional procedures can be misleading. This study was designed to assess the efficacy of event recording in evaluating long-term success in patients treated for atrioventricular nodal reentrant tachycardia (AVNRT) or right posteroseptally located accessory pathways (RPS) either by radiofrequency (RF) or by cryoablation (CA). Sixty-three patients with AVNRT and eight with RPS were randomized. Patients were encouraged to activate an event recorder in the case of recurrent palpitations for the first 3 months. One year after the procedure, patients were asked specific arrhythmia related questions. Thirty-six patients underwent RF and 35 CA. Acute success was finally achieved in 34 (94%) patients in the RF and 33 (94%) in the CA groups. Assessment of long-term success demonstrated a similar proportion of palpitations in the RF and CA groups: 11 (31%) vs. 17 (49%). Only 12 patients activated the event recorder, four patients in RF, including one patient with chest pain, and eight in the CA group. Analysis of recordings revealed recurrent AVNRT or circus movement tachycardia in four patients (one RF and three CA), atrial fibrillation in one RF patient, and sinus tachycardia in six (one RF and five with CA). In addition, a complete 12 lead ECG of a recurrent arrhythmia was made in three RF and two CA patients (in-hospital or after the event recording). A total of seven patients underwent a second procedure (four RF and three CA). Without the event recorder, seven patients would have been misclassified as having recurrent arrhythmia. Event recording enhances the sensitivity of detecting arrhythmia recurrences in evaluating therapy efficacy and should be considered in every interventional follow-up study. Analysis of recordings showed that CA is as effective as RF in the treatment of AVNRT and RPS at long-term follow-up.

P4-72: Catheter based cryoablation and radiofrequency ablation for atrial fibrillation results in conductive heat transfer from and to the esophagus

Left atrial ablation using radiofrequency (RF) energy has been associated with injury to the esophagus (ESO). Cryoablation (CRYO) is an alternative ablation modality for pulmonary vein isolation (PVI); but, the character of heat transfer from the ESO in humans during focal CRYO has not been described. We report on luminal ESO temperature (LET) changes in 10 patients (54 ± 9.8 y) undergoing PVI using a hybrid RF/CRYO ablation strategy. RF ablation was done with an 8mm tip catheter (30-65W) and CRYO was done with a 6 mm cryo catheter (−75 °C). LET was recorded with a temperature probe advanced to the level of the ablation catheter during all left atrial lesions. RF ablation in proximity to the ESO resulted in a rise in LET in all patients (26/683 lesions ≥ 0.5 °C rise, ΔT = 0.67 ± 0.3 °C). RF was discontinued when a temperature rise was evident, and these areas were marked for CRYO. Each CRYO was continued for 250 s regardless of observed LET. An average of 16.8 ± 14.3 CRYO lesions per patient were placed along the posterior left atrium where ablation was required adjacent to the ESO. All patients exhibited ESO cooling during CRYO. For 61 of 168 CRYO lesions, LET decreased at least 0.1 °C. Temperatures declined up to 15.6 °C from baseline (2.1 ± 3.1 ° C, mean ± SD). Minimum LET occurred after discontinuation of CRYO in 33% of lesions. The lowest LET recorded was 21.0 °C and the largest temperature drop after discontinuation of CRYO was 1.6 °C. In locations where RF produced a rapid temperature rise, a rapid temperature decrease was observed with CRYO. All LET changes occurred when CRYO was applied within 2.1 cm of the luminal ESO marker. We conclude that: 1) the relationship between the esophagus and left atrium often favors efficient energy transfer during RF or CRYO ablation; 2) CRYO can produce significant ESO cooling; and 3) similarity in the time course of LET changes during RF or CRYO ablation suggests that conduction is a mechanism for RF to act as a heat source or CRYO to act as a heat sink during left atrial ablation. Further studies are required to assess the character and consequence of energy transfer from the esophagus during catheter based focal CRYO.

P2-100: Single center experience with cryoablation in pediatric patients

Transcatheter cryoablation (CA) is an emerging option for the treatment of arrhythmias in children. Advantages over radiofrequency ablation (RFA) include added safety due to decreased risk of damage to critical structures such as the AV-node, increased patient comfort, and decreased risk of perforation and embolization. CA may create temporary lesions which inhibit electrical activity prior to complete tissue destruction. As a result, the electrophysiologic effects of potential lesions can be previewed before irreversibly damaging the myocardium, a tool that is especially useful when introducing lesions in the proximity of the AV-node. Limited data exists regarding the use of CA in children. We herein report a single center’s experience with CA in the pediatric population.

P4-75: Continuous SVC phrenic nerve pacing during cryo ablation of the right superior pulmonary vein: Early warning method for avoiding diaphragmatic paralysis

Ablation around pulmonary veins (PV) with ultrasound or cryo balloons may be effective in eliminating atrial fibrillation (AF). This intervention may be complicated by damage to adjacent structures including the right phrenic nerve during ablation near the right superior PV (RSPV.) In theory, early detection of phrenic nerve injury may limit long-term damage. We therefore sought to determine the utility of continuous phrenic nerve pacing during PV isolation with a steerable cryoballoon system in patients with AF.

Intraoperative Ar-He targeted cryoablation for advanced pancreatic carcinoma

目的 探讨术中氩靶向冷冻治疗系统(即氩氦刀)治疗晚期胰腺癌的安全性及疗效.方法2001-2002年期间8例晚期胰腺癌使用了术中氩氦刀治疗.结果8例晚期胰腺癌病人中,平均生存期为8.6个月,1例目前仍然存活.5例腹痛病人,3例完全缓解,2例部分缓解;1例腰背痛病人,疼痛部分缓解.结论术中氩氦刀治疗尽管不能明显延长晚期胰腺癌病人的平均生存期,但能明显缓解病人的疼痛,提高病人的生活质量,仍不失为一种有效的晚期胰腺癌的姑息治疗方法。