Computer 3D modeling of radiofrequency ablation of atypical cartilaginous tumours in long bones using finite element methods and real patient anatomy.

BACKGROUND: Radiofrequency ablation (RFA) is a minimally invasive technique used for the treatment of neoplasms, with a growing interest in the treatment of bone tumours. However, the lack of data concerning the size of the resulting ablation zones in RFA of bone tumours makes prospective planning challenging, needed for safe and effective treatment. METHODS: Using retrospective computed tomography and magnetic resonance imaging data from patients treated with RFA of atypical cartilaginous tumours (ACTs), the bone, tumours, and final position of the RFA electrode were segmented from the medical images and used in finite element models to simulate RFA. Tissue parameters were optimised, and boundary conditions were defined to mimic the clinical scenario. The resulting ablation diameters from postoperative images were then measured and compared to the ones from the simulations, and the error between them was calculated. RESULTS: Seven cases had all the information required to create the finite element models. The resulting median error (in all three directions) was -1 mm, with interquartile ranges from -3 to 3 mm. The three-dimensional models showed that the thermal damage concentrates close to the cortical wall in the first minutes and then becomes more evenly distributed. CONCLUSIONS: Computer simulations can predict the ablation diameters with acceptable accuracy and may thus be utilised for patient planning. This could allow interventional radiologists to accurately define the time, electrode length, and position required to treat ACTs with RFA and make adjustments as needed to guarantee total tumour destruction while sparing as much healthy tissue as possible.

Radiofrequency ablation of osteoid osteoma: Aiming for excellent outcomes in an Australasian context.

INTRODUCTION: To report a series of patients with osteoid osteoma treated by radiofrequency ablation in whom no complications or recurrences occurred. METHODS: Over a 13-year period, 32 consecutive patients with osteoid osteoma were treated by radiofrequency ablation in an Australasian teaching centre. RESULTS: All patients had resolution of symptoms with no complication or recurrence. CONCLUSIONS: This series is further evidence for the use of radiofrequency ablation as the primary treatment for osteoid osteoma.

Double ventricular response in dual AV nodal pathways mimicking interpolated premature beat.

Double ventricular response in dual atrioventricular (AV) nodal pathways can result in nonreentrant supraventricular tachycardia. Since this condition was first described in 1979, around 20 cases have been reported. Here, we present the case of a patient with a confirmed diagnosis of double ventricular response in dual AV nodal pathways resembling an interpolated premature beat who underwent successful radiofrequency ablation of the slow pathway.

Magnetic resonance imaging guided transatrial electrophysiological studies in swine using active catheter tracking - experience with 14 cases.

OBJECTIVES: To evaluate the feasibility of performing comprehensive Cardiac Magnetic resonance (CMR) guided electrophysiological (EP) interventions in a porcine model encompassing left atrial access. METHODS: After introduction of two femoral sheaths 14 swine (41 ± 3.6 kg) were transferred to a 1.5 T MR scanner. A three-dimensional whole-heart sequence was acquired followed by segmentation and the visualization of all heart chambers using an image-guidance platform. Two MR conditional catheters were inserted. The interventional protocol consisted of intubation of the coronary sinus, activation mapping, transseptal left atrial access (n = 4), generation of ablation lesions and eventually ablation of the atrioventricular (AV) node. For visualization of the catheter tip active tracking was used. Catheter positions were confirmed by passive real-time imaging. RESULTS: Total procedure time was 169 ± 51 minutes. The protocol could be completed in 12 swine. Two swine died from AV-ablation induced ventricular fibrillation. Catheters could be visualized and navigated under active tracking almost exclusively. The position of the catheter tips as visualized by active tracking could reliably be confirmed with passive catheter imaging. CONCLUSIONS: Comprehensive CMR-guided EP interventions including left atrial access are feasible in swine using active catheter tracking. KEY POINTS: • Comprehensive CMR-guided electrophysiological interventions including LA access were conducted in swine. • Active catheter-tracking allows efficient catheter navigation also in a transseptal approach. • More MR-conditional tools are needed to facilitate left atrial interventions in humans.

How to Achieve Complete and Permanent Pulmonary Vein Isolation without Complications.

The efficacy and safety of catheter ablation for the management of atrial fibrillation (AF) has been improved in recent years. Radiofrequency (RF) catheter ablation for maintaining sinus rhythm is superior to the current antiarrhythmic drug therapy in selected patients. Pulmonary vein isolation (PVI) is the cornerstone of various catheter ablation strategies. It is well recognized that pulmonary vein (PV) antrum contributes to the AF initiation and/or perpetuation. Since PV stenosis is a complication of ablation within a PV, the ablation site for PVI has shifted to the junction between the left atrium and the PV rather than the ostium of the PV. However, PV reconnection after ablation is the major cause of recurrence of AF. The recovery of PV conduction could be caused by anatomical variations such as the failure to produce complete transmural lesion or gaps at the ablation line due to the transient electrophysiologic effects from the RF ablation. In this review, we discussed several factors to be considered for the achievement of the best PVI, including clinical aspects and technical aspects.

Periprocedural stroke and bleeding complications in patients undergoing catheter ablation of atrial fibrillation with different anticoagulation management: results from the Role of Coumadin in Preventing Thromboembolism in Atrial Fibrillation (AF) Patients Undergoing Catheter Ablation (COMPARE) randomized trial.

BACKGROUND: Periprocedural thromboembolic and hemorrhagic events are worrisome complications of catheter ablation for atrial fibrillation (AF). The periprocedural anticoagulation management could play a role in the incidence of these complications. Although ablation procedures performed without warfarin discontinuation seem to be associated with lower thromboembolic risk, no randomized study exists. METHODS AND RESULTS: This was a prospective, open-label, randomized, parallel-group, multicenter study assessing the role of continuous warfarin therapy in preventing periprocedural thromboembolic and hemorrhagic events after radiofrequency catheter ablation. Patients with CHADS2 score ≥1 were included. Patients were randomly assigned in a 1:1 ratio to the off-warfarin or on-warfarin arm. The incidence of thromboembolic events in the 48 hours after ablation was the primary end point of the study. The study enrolled 1584 patients: 790 assigned to discontinue warfarin (group 1) and 794 assigned to continuous warfarin (group 2). No statistical difference in baseline characteristics was observed. There were 39 thromboembolic events (3.7% strokes [n=29] and 1.3% transient ischemic attacks [n=10]) in group 1: two events (0.87%) in patients with paroxysmal AF, 4 (2.3%) in patients with persistent AF, and 33 (8.5%) in patients with long-standing persistent AF. Only 2 strokes (0.25%) in patients with long-standing persistent AF were observed in group 2 (P<0.001). Warfarin discontinuation emerged as a strong predictor of periprocedural thromboembolism (odds ratio, 13; 95% confidence interval, 3.1-55.6; P<0.001). CONCLUSION: This is the first randomized study showing that performing catheter ablation of AF without warfarin discontinuation reduces the occurrence of periprocedural stroke and minor bleeding complications compared with bridging with low-molecular-weight heparin. CLINICAL TRIAL REGISTRATION URL: http://www.clinicaltrials.gov. Unique identifier: NCT01006876.

How to Achieve Complete and Permanent Pulmonary Vein Isolation without Complications

The efficacy and safety of catheter ablation for the management of atrial fibrillation (AF) has been improved in recent years. Radiofrequency (RF) catheter ablation for maintaining sinus rhythm is superior to the current antiarrhythmic drug therapy in selected patients. Pulmonary vein isolation (PVI) is the cornerstone of various catheter ablation strategies. It is well recognized that pulmonary vein (PV) antrum contributes to the AF initiation and/or perpetuation. Since PV stenosis is a complication of ablation within a PV, the ablation site for PVI has shifted to the junction between the left atrium and the PV rather than the ostium of the PV. However, PV reconnection after ablation is the major cause of recurrence of AF. The recovery of PV conduction could be caused by anatomical variations such as the failure to produce complete transmural lesion or gaps at the ablation line due to the transient electrophysiologic effects from the RF ablation. In this review, we discussed several factors to be considered for the achievement of the best PVI, including clinical aspects and technical aspects.

Irreversible electroporation of a hepatocellular carcinoma lesion adjacent to a transjugular intrahepatic portosystemic shunt stent graft.

We report in a 65-year-old man hepatocellular carcinoma adjacent to a transjugular intrahepatic portosystemic shunt stent-graft which was successfully treated with irreversible electroporation (IRE). IRE is a new non-thermal tissue ablation technique which uses electrical pulses to induce cell necrosis by irreversible membrane poration. IRE proved to be more advantageous in the ablation of perivascular tumor with little injury to the surrounding structures.

Irreversible Electroporation of a Hepatocellular Carcinoma Lesion Adjacent to a Transjugular Intrahepatic Portosystemic Shunt Stent Graft

We report in a 65-year-old man hepatocellular carcinoma adjacent to a transjugular intrahepatic portosystemic shunt stent-graft which was successfully treated with irreversible electroporation (IRE). IRE is a new non-thermal tissue ablation technique which uses electrical pulses to induce cell necrosis by irreversible membrane poration. IRE proved to be more advantageous in the ablation of perivascular tumor with little injury to the surrounding structures.

Does the expression of transforming growth factor ß-1: affect the outcome of the radiofrequency modified maze procedure in patients with rheumatic atrial fibrillation?

We investigated whether the expression of transforming growth factor ß-1 in the left atrial appendage affected the outcome of the radiofrequency modified maze procedure in patients with rheumatic valve disease and long-standing persistent atrial fibrillation.Messenger RNA and protein expression of transforming growth factor ß-1 and volume fractions of collagen types I and III were measured in 80 patients with rheumatic valve atrial fibrillation who underwent valve surgery with the radiofrequency modified maze procedure; the same was done in a control group of 20 patients with rheumatic valve disease and sinus rhythm who underwent valve surgery alone.At 6 months' follow-up, atrial fibrillation recurred in 24 of the 80 patients in the study group. The messenger RNA and protein expressions of transforming growth factor ß-1, collagen type I volume fraction, and left atrial dimension had increased gradually in the control group and in the study subgroups that maintained sinus rhythm or relapsed into atrial fibrillation (P <0.05). The messenger RNA and protein expressions of transforming growth factor ß-1 correlated positively with collagen type I volume fraction (r=0.723, P <0.001 and r=0.745, P <0.001, respectively) and left atrial dimension (r=0.762, P <0.001 and r=0.765, P <0.001, respectively). In the sinus rhythm-maintained subgroup, the patients who regained functional atrial contraction had lower messenger RNA and protein expression of transforming growth factor ß-1 than did the patients who failed to retain such function (P <0.05).We conclude that the expression of transforming growth factor ß-1 in the resected left atrial appendage affects the recurrence of atrial fibrillation and restoration of functional left atrial contraction after the radiofrequency modified maze procedure.

Taquicardiomiopatía, causa reversible de insuficiencia cardiaca: caso clínico / Tachycardiomyopathy as a reversible cause of heart failure: Report of one case

Tachycardiomyopathy is a potentially reversible cause of heart failure. It can be induced by supraventricular or ventricular arrhythmias. When these are treated, systolic function improves or normalizes. We report a 20year-old male with deterioration of left ventricular function and dilated cardiomyopathy secondary to an incessant atrial tachycardia that was treated with radiofrequency catheter ablation. After the procedure, the patient experienced a significant improvement of his ventricular function.

Ablación de fibrilación auricular en un paciente con miocardiopatía dilatada / Ablation of Atrial Fibrillation in a Patient with Dilated Cardiomyopathy

El tratamiento invasivo de la fibrilación auricular en pacientes con miocardiopatía dilatada con sospecha de taquicardiomiopatía representa una decisión difícil y controversial. En esta presentación se describe el caso de un paciente de 57 años, internado por insuficiencia cardíaca congestiva progresiva. En el electrocardiograma se evidenció fibrilación auricular de alta respuesta ventricular y en el ecocardiograma, miocardiopatía dilatada con deterioro grave de la función del ventrículo izquierdo e insuficiencia mitral grave sin compromiso orgánico valvular. Se descartó enfermedad coronaria. Se planteó la ablación por radiofrecuencia como la mejor alternativa para su cuadro. El paciente recuperó ritmo sinusal, con el cual permanece desde hace 2 años, con evolución asintomática y mejoría de todos los parámetros ecocardiográficos.

Invasive treatment of atrial fibrillation in patients with dilated cardiomyopathy and suspicion of tachycardia induced cardiomyopathy is a difficult and controversial decision. We describe the case of a 57 year-old patient who was hospitalized due to progressive congestive heart failure. The electrocardiogram showed atrial fibrillation with high ventricular response and the echocardiogram revealed the presence of dilated cardiomyopathy with severe left ventricular dysfunction and severe mitral regurgitation with no evidence of organic compromise of the mitral valve. Coronary artery disease was ruled out. Radiofrequency ablation of atrial fibrillation was the best option to treat the arrhythmia. Sinus rhythm was restored and the patient remains without arrhythmia 2 years after the procedure. He is asymptomatic and presents improvement of the echocardiographic parameters.

Effects of percutaneous radiofrequency ablation and repeat hepatectomy for the treatment of solitary recurrent hepatocellular carcinoma with the diameter no more than 3 cm / 中华消化外科杂志

Objective To compare the efficacy of percutaneous radiofrequency ablation (PRFA) and repeat hepatectomy for solitary recurrent hepatocellular carcinoma (HCC) with the diameter≤3 cm. Methods The clinical data of 151 patients with recurrent HCC (diameter≤3 cm) who were admitted to the Cancer Center of Sun Yat-Sen University from January 1999 to December 2009 were retrospectively analyzed. Of all the patients, 79received PRFA (PRFA group) and 72 received repeat hepatectomy (repeat hepatectomy group). The survival rate, morbidity and recurrence of the tumor between the two groups were compared. All data were analyzed using t test, chi-square test or Log-rank test, and the survival of the patients were analyzed using the Kaplan-Meier method. Results The mobidities of the PRFA group and repeat hepatectomy group were 13% (10/79) and 36%(26/72), respectively, with a significant difference between the two groups (x2=11.411, P＜0.05). The cumulative 1-, 2-, 3-, 4-, 5-year survival rates were 89.7%, 75.2%, 67.1%, 61.5%, 56.6% in the PRFA group, and 86.0%, 67.6%, 53.6%, 44.1%, 40.2% in the repeat hepatectomy group, with no significant difference between the two groups (x2=1.610, P＞0.05). The cumulative 4-, 5-year survival rates of the PRFA group were significant higher than those in the repeat hepatectomy group (x2=4.682, 4. 196, P ＜ 0.05). The local tumor recurrence rate of the PRFA group was 5% (4/79), and the incisal margin recurrence rate was 3% (2/72) in the repeat hepatectomy group, with no significant difference between the two groups (x2=0.565, P＞0.05). Conclusion As a less invasive treatment method, PRFA is superior to repeat hepatectomy for solitary recurrent HCC with the diameter≤3 cm.

Preparation of EUS-guided radiofrequency probe and test of its functions / 中华消化内镜杂志

Objective To prepare a radiofrequency (RF) ablation probe guided by endoscopic ultrasonography (EUS) and to evaluate its efficacy and safety. Methods A modified 19-gauge needle ( Olympus) was used, which was electrically insulated with shrink tubing, with the tip of lcm naked. The insulation was tested, and the current signal was stable. Three rabbits were anesthetized with 8% chloral hydrate ( 3 ml/kg) intraperitoneally, fixed on the dissecting table. A standard neutral pad was applied to the thigh of the rabbit to complete the electrical circuit, both the pad and the needle electrode connected with RF generator. After anesthesia was ready, the needle was advanced through the gastric wall into the liver. Ablations were performed three times in the same zone. Extent and tissue lesion were measured after ablation. Results Ablation could be successfully performed by the needle electrode, with brown lesions surrounded by normal hepatic tissue. The mean diameter of the ablated zone in the liver was 1.0 cm× 1.2 cm. After ablation,specimens along the passage were subjected to NADH staining, and no lesions were found. HE and NADH staining showed no viable cells in the central ablation area. Conclusion With the advance of the technology and selection of materials, an EUS-guided needle electrode can be made. This preliminary animal trial demonstrates that radiofrequency ablation can be performed effectively and safely by using this EUS-guided needle electrode.

Efficacy evaluation of laparoscopic surgery in the treatment of 128 patients with liver cancer / 中华消化外科杂志

Objective To investigate the value of laparoscopy in the treatment of liver cancer.Methods The clinical data of 128 liver cancer patients who received laparoscopic surgery at Southwest Hospital from March 2007 to October 2009 were retrospectively analyzed.Of all patients,116 were with primary liver cancer,and 12 with metastatic liver cancer.There were 107 patients who received laparoscopie bepatectomy,15 received laparoscopic radiofrequency ablation(RFA)and 6 received laparoscopic ligation of the right branch of portal vein.Results Of the 107 patients who received laparoscopic bepatectomy,7 were converted to open surgery,and 5 were converted to hand-assisted laparoscopic hepatectomy.Anatomical hepatectomy was performed on 88 patients,including left lateral lobectomy on 21,left hemihepatectomy on 15,extended left hemihepatectomy on 2,medial lobectomy on 1,right hemihepatectomy on 11,right posterior lobeetomy on 9 and hepatic segmentectomy on 29.Combined hepatic resection was performed on 4 patients,and nonanatomical hepatectomy on 15.The mean oporatire time and blood loss were(228±92)minutes and(393±213)ml,with no operative mortality.The mean postoperative hospital stay was(8±4)days,and the incidence of complications was 15%(16/107).A total of 126 patients were followed up for 1-42 months,12 patients with laparoscopic hepatectomy died within 16 months,with the mean survival time of(118±7)weeks and the mean tumor free survival time of(105±7)weeks;2 patients with laparoscopic RFA died within 11 months:2 patients with laparoseopie ligation of the right branch of portal vein received two-stage radical resection.Conclusion Laparoscopic surgery is safe and feasible with the advantages of minimal operative trauma and quick recovery of patients when it is applied to the treatment of liver cancer.

Hypertonic saline enhanced radiofrequency ablation in the treatment of liver cancer / 中华消化外科杂志

Objective To investigate the efficacy and safety of hypertonie saline enhanced radiofrequency ablation (RFA) in the treatment of liver cancer. Methods The clinical data of 42 patients with primary liver cancer (n = 28) or metastatic liver eancer (n = 14) who had been admitted to First Affiliated Hospital of Nanjing Medical University from September 2001 to December 2007 were collected. Forty-eight lesions were detected with a diameter ranging from 1.2 cm to 7.5 cm. RFA electrode and 20G needle were pricked into the target lesion under the guidance of B ultrasound or computed tomography (CT) through percutaneoas puncture or open approaches. An amount of 5-10 ml hypertonie saline was infused through the needle at regular intervals during RFA. All patients were followed up for 3-79 months. Contrast-enhanced ultrasound and CT scanning were performed postoperatively to determine the efficacy of RFA. The levels of alpha-fetoprotein (AFP) before and after treatment were compared using t test, and the survival of the patients were analyzed using a Kaplan-Meier survival curve. Results The AFP expression changed to negative in 14 out of the 18 AFP-positive patients, with statistical difference (t =7.703, P <0.05). The complete necrosis rate of tumors was 94% (45/48), and the necrosis rate of tumors with diameter of ≤4.0 cm reached 100% (35/35). The incidence of complication was 5% (2/42). No perioperative mortality occurred. The 1-, 2-, 3-year survival rates were 91%, 85% and 70%, respectively. Conclusions Hypertonic saline enhanced RFA in the treatment of liver cancer was proved to be safe and effective.

Comparison of 2 radiofrequency ablation methods in idiopathic left posterior fasci-cular ventricular tachycardia / 第三军医大学学报

Objective To investigate whether taking diastolic potential(DP)and earliest Purkinje potential(PP)as ablation targets together is superior to taking earliest PP alone in patients with left posterior fascicular ventricular tachycardia(VT).MethodsTotally 18 patients who were admitted in our department from May 2006 to May 2009 were enrolled,and the results of their electrophysiological examination were analyzed.According to radiofrequency(RF)ablation targets,patients were classified into 2 groups:DP+PP group(DP and PP as ablation targets together)and PP group(PP as the target alone).Successful RF ablation was established when the ventricular tachycardia was no longer inducible.The acute success rate,recurrent rate,number of ablation application,procedure time,X-ray exposure and complications were compared between DP+PP and PP groups.ResultsThere was 1 case receiving no ablation because of not being induced to clinical VT.Seventeen cases were induced to clinical VT and displayed right bundle branch block(RBBB)and left axis morphology(DP+PP group 7 cases,and PP group 10 cases).All cases were successfully ablated,their DP-Q interval and PP-Q interval were 60.17?8.16 and 30.64?7.19 ms,respectively.There was no significant difference between the 2 groups in the age,ventricular tachycardial cycle,procedure time and recurrent rate.Compared to the PP group,the number of RF application in DP+PP group was fewer(4.55?2.07 vs 7.50?1.64,P=0.04),and X-ray exposure time was a little longer(18.33?1.51 min vs 15.37?2.77 min,P=0.03).There was neither left posterior fascicular block nor other complications seen in the 2 groups.The follow-up period was 14.29?10.05 months,and during this there was 1 case recurrence in DP group(2 months after procedure)and 1 case in PP group(1 month after procedure)respectively.ConclusionThe 2 methods are effective and safe for successful ablation of left posterior fascicular VT.Compared to ablation of earliest PP site alone,ablation of DP+PP might need fewer times of RF application but longer X-ray exposure time.

DISCRETE RADIOFREQUENCY CATHETER ABLATION FOR PAROXYSMAL ATRIAL FIBRILLATION IN A DOG MODEL / 解放军医学杂志

To investigate an approach of treatment for atrial fibrillation with discrete ablation lesion, 12 dogs with experimental atrial fibrillation underwent radiofrequency catheter ablation. Atrial lesion was made at the most vulnerable site. The results showed that in 10 of 12 dogs persistent fibrillation could be ablated. There was no significant change in sinus heart rate, P wave duration, and corrected sinoatrial node recovery time (cSNRT). The results suggested that paroxysmal atrial fibrillation could be eliminated by point ablation of the lesion, and that trigger activity might be involved in the mechanism of atrial fibrillation.