Efficacy Of Radiofrequency Research Articles

RADIOFREQUENCY FACILITATED MANUAL SEMI-ENDOSCOPIC DISCECTOMY UTILIZING THE DISC FX® SYSTEM IN THE TREATMENT OF DISC-PREDOMINATE LUMBAR SPINAL STENOSIS

Background: Lumbar spinal stenosis (LSS) occurs with increasing prevalence in the elderly population. The American Academy of Orthopedic Surgeons has estimated that by 2021, 2.4 million adults in the United States (8-11% of the population) will be affected by this condition. Surgical options for LSS are being performed with increased frequency, high cost, and substantial risk of life-threatening complications. While nonsurgical treatment options for LSS are available, they are limited by patient selection (ligamentum flavum hypertrophy) or high rates of reoperation (Interspinous process spacer devices). This study is the first to suggest a minimally invasive treatment option for disc-predominate lumbar central canal stenosis. Objectives: To evaluate the clinical efficacy of radiofrequency facilitated manual semi-endoscopic discectomy utilizing the Disc FX® system in the treatment of disc-predominate lumbar spinal stenosis. Study Design: Single center, prospective, observational study. Setting: Multi-specialty private practice clinic. The Medical Group of South Florida, Jupiter, FL. Methods: This study involved 6 patients with disc-predominant lumbar central spinal stenosis. All patients were treated with the Disc FX® system. Radiographic evidence of central lumbar stenosis was confirmed by measurement of minimum AP canal diameter (mm) performed by 1 board-certified neuroradiologist. Inclusion criteria included absence of lumbar surgery, physical therapy within the previous 6 months, failure of epidural steroid injections (3) within the previous 8 months, spondylolisthesis limited to Grade I, disc height > 50%, presence of low back axial pain + leg pain exacerbated by walking, and relieved with sitting or forward flexion, absence of dermatomal radicular leg pain, radiographic evidence of disc displacement > 4 mm from disc endplate. Zurich claudication (symptom severity and physical function scale was administered 1 week preoperatively, and again 6 months postoperatively. There were no patients lost to follow up. Results: All patients in the study demonstrated moderate-severe or severe central canal stenosis, with an average AP canal diameter of 6.63 mm for all treated disc levels and 5.5 mm for the most severe levels. There was a mean improvement of 57% in a symptom severity scale and 56% in the physical function scale at 6 months. This exceeds the improvement reported with interspinous spacer devices. Limitations: Limitations include very small sample size, observational design, non-randomization, absence of share controls, short follow-up period. Conclusion: For patients suffering from discpredominant lumbar spinal stenosis, The Disc FX® System provides an effective, low-cost alternative to surgical intervention. Key words: Spinal, stenosis, claudication, disc, Disc FX®, operative, minimally invasive, Zürich claudication score

Developing and validating radio frequency pasteurisation processes for almond kernels

The efficacy of radio frequency (RF) treatment to inactivate Escherichia coli ATCC 25922 used as a surrogate of pathogenic Salmonella in almond kernels was investigated. A pilot-scale, 27 MHz, 6 kW RF unit was used to study the heating uniformity of almond kernels at the moisture content of 10.01% w.b. using two types of plastic containers. Pasteurisation processes were developed and validated for almond kernels and the product quality after RF treatments was evaluated. The results showed that only 6.4 min was needed to raise the central temperature of 1.5 kg almond kernels from 25 °C to 72 °C by using RF energy as compared to 276 min using 72 °C hot air in a five-layer container. An effective RF treatment protocol was obtained using an electrode gap of 11 cm, 72 °C hot air surface heating, intermittently rearranging the five-layers in less than 1 min, and holding in 72 °C hot air for 15 min for pasteurisation to achieve more than 4-log reductions of E. coli ATCC 25922, drying to reduce the moisture level, and cooling in the single layer by forced room air to avoid product quality degradation. The moisture content, fatty acid, peroxide value and colour values of RF treated almond kernels met the good quality standard used by the almond industry. Therefore, RF treatments are an effective and rapid heating method for potentially pasteurising Salmonella in almond kernels.

Intraosseous basivertebral nerve ablation for the treatment of chronic low back pain: a prospective randomized double-blind sham-controlled multi-center study

PurposeTo evaluate the safety and efficacy of radiofrequency (RF) ablation of the basivertebral nerve (BVN) for the treatment of chronic low back pain (CLBP) in a Food and Drug Administration approved Investigational Device Exemption trial. The BVN has been shown to innervate endplate nociceptors which are thought to be a source of CLBP.MethodsA total of 225 patients diagnosed with CLBP were randomized to either a sham (78 patients) or treatment (147 patients) intervention. The mean age within the study was 47 years (range 25–69) and the mean baseline ODI was 42. All patients had Type I or Type II Modic changes of the treated vertebral bodies. Patients were evaluated preoperatively, and at 2 weeks, 6 weeks and 3, 6 and 12 months postoperatively. The primary endpoint was the comparative change in ODI from baseline to 3 months.ResultsAt 3 months, the average ODI in the treatment arm decreased 20.5 points, as compared to a 15.2 point decrease in the sham arm (p = 0.019, per-protocol population). A responder analysis based on ODI decrease ≥ 10 points showed that 75.6% of patients in the treatment arm as compared to 55.3% in the sham control arm exhibited a clinically meaningful improvement at 3 months.ConclusionPatients treated with RF ablation of the BVN for CLBP exhibited significantly greater improvement in ODI at 3 months and a higher responder rate than sham treated controls. BVN ablation represents a potential minimally invasive treatment for the relief of chronic low back pain.Graphical abstractThese slides can be retrieved under Electronic Supplementary Material.

Efficacy and Safety of Radiofrequency Ablation for Focal Hepatic Lesions Adjacent to Gallbladder: Reconfiguration of the Ablation Zone through Probe Relocation and Ablation Time Reduction

PurposeTo evaluate the safety and efficacy of radiofrequency (RF) ablation for treatment of focal hepatic lesions adjacent to the gallbladder with electrode relocation and ablation time reduction. Materials and MethodsThirty-nine patients who underwent RF ablation for focal hepatic lesions adjacent to the gallbladder (≤ 10 mm) were evaluated retrospectively from January 2011 to December 2014 (30 men and 9 women; age range, 51–85 y; mean age, 65 y). Of 36 patients with hepatocellular carcinoma, 3 had a second treatment for recurrence (mean tumor size, 15 mm ± 6). Patients were divided into 2 subgroups based on lesion distance from the gallbladder: nonabutting (> 5 mm; n = 19) and abutting (≤ 5 mm; n = 20). Electrodes were inserted parallel to the gallbladder through the center of a tumor in the nonabutting group and through the center of the expected ablation zone between a 5-mm safety zone on the liver side and the gallbladder in the abutting group. Ablation time was decreased in proportion to the transverse diameter of the expected ablation zone. ResultsTechnical success and technical effectiveness rates were 89.7% and 97.4%, respectively, with no significant differences between groups (P = 1.00). Local tumor progression was observed in 3 patients (1 in the nonabutting group and 2 in the abutting group; P = 1.00). There were no major complications. The gallbladder was thickened in 10 patients, with no significant difference between groups (P = .72). Biloma occurred in 1 patient in the nonabutting group. ConclusionsRF ablation with electrode relocation and reduction of ablation time can be a safe and effective treatment for focal hepatic lesions adjacent to the gallbladder.

Comparison of catheter ablation for paroxysmal atrial fibrillation between cryoballoon and radiofrequency: a meta-analysis.

The present systematic review and meta-analysis aimed to assess and compare the safety and efficacy of radiofrequency (RF) and cryoballoon (CB) ablation for paroxysmal atrial fibrillation (PAF). RF and CB ablation are two frequently used methods for pulmonary vein isolation in PAF, but which is a better choice for PAF remains uncertain. A systematic review was conducted in Medline, PubMed, Embase, and Cochrane Library. All trials comparing RF and CB ablation were screened and included if the inclusion criteria were met. A total of 38 eligible studies, 9 prospective randomized or randomized controlled trials (RCTs), and 29 non- RCTs were identified, adding up to 15,496 patients. Pool analyses indicated that CB ablation was more beneficial in terms of procedural time [standard mean difference = -0.58; 95% confidence interval (CI), -0.85 to -0.30], complications without phrenic nerve injury (PNI) [odds ratio (OR) = 0.79; 95% CI, 0.67-0.93; I 2 = 16%], and recrudescence (OR = 0.83; 95% CI, 0.70-0.97; I 2 = 63%) for PAF; however, the total complications of CB was higher than RF. The subgroup analysis found that, compared with non-contact force radiofrequency (non-CF-RF), both first-generation cryoballoon (CB1) and second-generation cryoballoon (CB2) ablation could reduce complications with PNI, procedural time, and recrudescence. However, the safety and efficacy of CB2 was similar to those of CF-RF. Available overall and subgroup data suggested that both CB1 and CB2 were more beneficial than RF ablation, and the main advantages were reflected in comparing them with non-CF-RF. However, CF-RF and CB2 showed similar clinical benefits.

Circuit Impedance Could Be a Crucial Factor Influencing Radiofrequency Ablation Efficacy and Safety: A Myocardial Phantom Study of the Problem and its Correction.

Circuit impedance could affect the safety and efficacy of radiofrequency (RF) ablation. To perform irrigated RF ablations with graded impedance to compare (1) lesion dimensions and overheated dimensions in fixed power ablations (2) and in power corrected ablations. Ablations were performed with irrigated Navistar Thermocool catheter and Stockert EP shuttle generator at settings of 40 W power for 60 seconds, in a previously validated myocardial phantom. The impedance of the circuit was set at 60 Ω, 80 Ω, 100 Ω, 120 Ω, 140 Ω, and 160 Ω. The lesion and overheated dimensions were measured at 53 °C and 80 °C isotherms, respectively. In the second set of ablations, power was corrected according to circuit impedance. In total, 70 ablations were performed. The lesion volume was 72.0 ± 4.8% and 44.7 ± 4.6% higher at 80 Ω and 100 Ω, respectively, compared to that at 120 Ω and it was 15.4 ± 1.2%, 28.1 ± 2.0%, and 38.0 ± 1.8% lower at 140 Ω, 160 Ω, and 180 Ω, respectively. The overheated volume was four times larger when impedance was reduced to 80 Ω from 100 Ω. It was absent at 120 Ω and above. In the power corrected ablations, the lesion volumes were similar to that of 40 W/120 Ω ablations and there was no evidence of overheating. The lesion and overheated dimensions were significantly larger with lower circuit impedance during irrigated RF ablation and the lesion size was smaller in high impedance ablations. Power delivery adjusted to impedance using a simple equation improved the consistency of lesion formation and prevented overheating.

Combination of radiofrequency and intralesional steroids in the treatment of keloids: a pilot study.

None of therapeutic options for the treatment of keloids has been found completely effective and satisfactory. A combination approach is the best modality. To assess the clinical safety and efficacy of radiofrequency (RF) followed by intralesional (IL) steroid injection in keloids. This pilot study included 18 patients who were suffering from keloids. All patients were subjected to 3 to 4 sessions of RF followed by IL steroid injection. Assessment of the scar volume and both objective and subjective parameters has been performed before and after completion of the sessions. There was a significant reduction of volume of all lesions in all patients after a total of 3 to 4 sessions (p = .001), with a mean volume reduction of 95.4%. There was a significant reduction of keloid pliability, height, and erythema compared with baseline (p < .001). Patients reported a significant reduction of their subjective symptoms compared with baseline (p < .001). No pain, infection, nor bleeding were reported after the RF procedure. Radiofrequency tissue volume reduction combined with IL steroid is an effective treatment modality for keloids. It is an easy procedure with acceptable cosmetic outcome and less rate of recurrence.

Efficacy and survival analysis of percutaneous radiofrequency versus microwave ablation for hepatocellular carcinoma: an Egyptian multidisciplinary clinic experience.

Hepatocellular carcinoma (HCC) is a primary tumor of the liver with poor prognosis. For early stage HCC, treatment options include surgical resection, liver transplantation, and percutaneous ablation. Percutaneous ablative techniques (radiofrequency and microwave techniques) emerged as best therapeutic options for nonsurgical patients. We aimed to determine the safety and efficacy of radiofrequency and microwave procedures for ablation of early stage HCC lesions and prospectively follow up our patients for survival analysis. One Hundred and 11 patients with early HCC are managed in our multidisciplinary clinic using either radiofrequency or microwave ablation. Patients are assessed for efficacy and safety. Complete ablation rate, local recurrence, and overall survival analysis are compared between both procedures. Radiofrequency ablation group (n = 45) and microwave ablation group (n = 66) were nearly comparable as regards the tumor and patients characteristics. Complete ablation was achieved in 94.2 and 96.1% of patients managed by radiofrequency and microwave ablation techniques, respectively (p value 0.6) with a low rate of minor complications (11.1 and 3.2, respectively) including subcapsular hematoma, thigh burn, abdominal wall skin burn, and pleural effusion. Ablation rates did not differ between ablated lesions ≤ 3 and 3-5 cm. A lower incidence of local recurrence was observed in microwave group (3.9 vs. 13.5% in radiofrequency group, p value 0.04). No difference between both groups as regards de novo lesions, portal vein thrombosis, and abdominal lymphadenopathy. The overall actuarial probability of survival was 91.6% at 1 year and 86.1% at 2 years with a higher survival rates noticed in microwave group but still without significant difference (p value 0.49). Radiofrequency and microwave ablations led to safe and equivalent ablation and survival rates (with superiority for microwave ablation as regards the incidence of local recurrence).

Radiofrequency ablation for large hepatic hemangiomas: Initial experience and lessons

We aimed to assess the feasibility, safety, and efficacy of radiofrequency (RF) ablation for the treatment of large (≥5 cm in greatest diameter) hepatic hemangiomas. Thirty-six patients (15 male, 21 female; mean age 50 years) with 41 hepatic hemangiomas ≥5 cm in diameter were enrolled and treated with RF ablation attributable to the presence of enlargement tendency and/or persistent hemangioma-associated symptoms. Twenty patients had 24 hemangiomas <10 cm, and 16 patients had 17 hemangiomas ≥10 cm. Technical success, complications related to RF ablation, completed ablation, symptom relief, change in size of ablation zone, and recurrence of the residual tumor were analyzed. Of the 41 hemangiomas with a mean diameter 10 ± 4 cm (range, 5-22 cm), 26 subcapsular lesions were treated with a laparoscopic approach, and 15 lesions located in liver parenchyma underwent a computed tomography-guided percutaneous approach. RF ablation was performed successfully in all patients. There were 62 complications related to the ablation in 22 patients, including 6 of 20 patients with hemangiomas <10 cm and all the 16 patients with hemangiomas ≥10 cm. According to the Dindo-Clavien classification, 2 complications (lower esophageal fistula and acute respiratory distress syndrome, Grade III and Grade IV, respectively) were major in 2 patients with hemangiomas ≥10 cm; all the other were minor in 20 patients (Grade I). All the complications were recovered by conservative treatment. Thirty-eight (93%) of 41 hepatic hemangiomas were ablated completely, including all the 24lesions <10 cm and 14 of 17 lesions ≥10 cm. All the symptoms related to hemangiomas disappeared (n = 22) or were ameliorated (n = 4) after ablation. The mean diameter of ablation zone was decreased to 6 ± 3 cm (2-12 cm) in a mean follow-up period (X ± SD) of 15 ± 6 months (range, 6-24 months), without recurrence or enlargement of the 3 residual tumors. The present study supports RF ablation as an alternative treatment for hepatic hemangiomas ≥5 cm (but smaller than 10 cm) for the low risk of complications and likelihood of complete ablation, but, in contrast, RF ablation appears to be an inappropriate method for hepatic hemangiomas ≥10 cm because of the high occurrence rate of complications.

Sustained idiopathic ventricular tachycardia originating from the posteroseptal tricuspid annulus

Tricuspid annular ventricular tachycardia (VT) is a rarely encountered entity. Despite abundant data on idiopathic VTs, the prevalence and clinical characteristics of this infrequent form are not well defined and the efficacy of radiofrequency (RF) catheter ablation treatment remains unknown. We report on a case of a 44-year-old male presenting with symptomatic sustained idiopathic VT originating from the posteroseptal tricuspid annulus.

Radiofrequency Ablation: Effect of Tumor- and Organ-specific Pharmacologic Modulation of Arterial and Portal Venous Blood Flow on Coagulation Diameter in an N1-S1 Tumor Model

PurposeTo investigate inherent differences in vasculature of tumors versus normal parenchyma and efficacy of radiofrequency (RF) ablation with glucagon, adenosine, and a combination of the two compared with normal saline solution (NS) controls in an N1-S1 tumor model implanted in Sprague–Dawley rat livers. Materials and MethodsA total of 17 tumors were established in the left lobes of rats. Tumor perfusion relative to surrounding liver parenchyma was evaluated with contrast-enhanced ultrasound with intermittent-bolus technique before and after administration of glucagon, adenosine, a combination of the two, or NS. Tumors were ablated with a 22-gauge RF probe with 1 cm of exposed tip at 80 °C for 2 min. Tumor size, zone of necrosis, and viable tumor were measured in tumors after 2,3,5-triphenyltetrazolium chloride staining. Results were compared with degree of tumor perfusion. ResultsThe normalized tumor perfusion ratio did not significantly change with administration of NS (1.38% ± 3.93). Vasomodulation resulted in significant decreases in normalized tumor perfusion ratio: 66.22% ± 24.57 (P < .01) with glucagon, 71.45% ± 22.72 (P < .01) with adenosine, and 74.98% ± 16.58 (P < .01) with glucagon plus adenosine. After tumor ablation, there was an increase in size of the ablated area by 100%–165% in the three treatment groups compared with NS controls. Differences among treatment groups were not statistically significant. ConclusionsTumor blood flow may be significantly altered by using systemic injection of appropriate medications. This tumor- and organ-specific approach to tumor vasomodulation may be used to enhance current therapeutic options.

Radio-frequency heating to inactivate Salmonella Typhimurium and Escherichia coli O157:H7 on black and red pepper spice

The efficacy of radio-frequency (RF) heating to inactivate Salmonella Typhimurium and Escherichia coli O157:H7 on black and red pepper spice was investigated. A 27.12 MHz RF heating system consisted of two parallel-plate electrodes was used, with the sample being placed between them. Black peppers (whole and ground) and red peppers (+ 16 mesh, -16 + 25 mesh, and -25 mesh) inoculated with S. Typhimurium and E. coli O157:H7 were treated with RF energy during 50s for black peppers and 40s for red peppers, and color change of samples was evaluated after treatment. RF heating for 50s resulted in 2.80 to 4.29 log CFU/g reductions of S. Typhimurium and E. coli O157:H7 in black peppers and RF heating of red peppers for 40s reduced pathogens by 3.38 log CFU/g to more than 5 log CFU/g (below the detection limit) without affecting the color quality change. The results suggest that RF heating has the potential for novel thermal process to control foodborne pathogens in spice.

Radiofrequency ablation of atrial fibrillation in patients with mitral or aortic mechanical prosthetic valves: A feasibility, safety, and efficacy study

Patients with prosthetic valves have a high prevalence of atrial fibrillation (AF). We report a multicenter experience of performing pulmonary vein antral isolation (PVAI) in this challenging, high-risk cohort of patients. The purpose of this study was to assess the feasibility, safety, and efficacy of radiofrequency (RF) ablation for sinus rhythm restoration in AF patients with mitral or aortic mechanical prosthetic valves. A total of 50 patients with prosthetic valves (group I) who underwent RF ablation for AF between January 1, 2007, and April 30, 2009, were identified prospectively at four tertiary care centers. A matched group of 50 patients (group II) acted as controls. Total procedural time (199.4 ± 49 minutes vs 166.6 ± 27.5 minutes, P <.001) and fluoroscopy time (60 ± 17 minutes vs 53.8 ± 6.8 minutes, P <.01) were prolonged, with a higher incidence of atrial flutter at 3 months in group I (18% vs 6%, P = .1) compared to group II. At 12 months, 80% of patients in the valve group were in sinus rhythm after an average of 1.3 procedures, and 82% of controls were in sinus rhythm after an average 1.2 procedures (P = .9). There was a trend toward a higher nonfatal complication rate in the valve group than in the control group (8% vs 4%, P = .1). In patients with prosthetic valves, RF ablation for AF is feasible, safe, and efficacious, with a trend toward a higher nonfatal complication rate and an increased rate of postablation atrial flutter.

Traitement radiologique du carcinome hépatocellulaire en 2010

Several radiological techniques have been used for treating hepatocellular carcinoma. These include transcatheter arterial chemoembolization (TACE) and percutaneous therapy, such as radiofrequency (RF). The treatment efficacy of radiofrequency for hepatocellular carcinoma has been confirmed by several randomized and non randomized studies, with a benefit in terms of morbidity comparatively to surgery when cirrhosis is present. Radiofrequency ablation treatment is based on tumour size, shape and location, with a defined strategy and a proper patient selection. We will also review indications and technical aspects of transcatheter arterial chemoembolization (TACE). It is an accepted worldwide and effective treatment for patients with unresectable large or multinodular hepatocellular carcinoma. It improves significantly survival for adequate selected patients with preservation of liver function.

Radiofrequency ablation treatment in the pelvic cancer relapses of rectal carcinoma

Background: To evaluate retrospectively the technical feasibility, safety and efficacy of radiofrequency thermal ablation (RFA) in the treatment of recurrent rectal cancer that is painful, non-resectable and no longer susceptible to radiotherapy and chemotherapy. Materials and Methods: Ten patients, average age 64 years, with pelvic recurrence of rectal carcinoma were treated with RFA to reduce pain and limit the progression of local disease. The lesion mean size was 4.7 cm(range of 3.2e9 cm). RFA was performed with computed tomography-guided percutaneous approach using local anaesthesia and conscious sedation in all patients. The therapeutic outcomes were evaluated by contrast- enhanced TC after 1, 3, 6 and 12 months. The absence of tumour enhancement on the TC image was considered to indicate complete tumour necrosis. Results: Complete tumour necrosis was found in 3 patients, sub-total in the remaining 7. Complete pain relief was obtained in 6 patients and a significant reduction of pain in the remaining patients (mean VAS score from7.4 before treatment to 1.5 after treatment). Abscess formation in the pre-sacral space and a bladder-rectal fistula after RF treatment was observed in 2 patients. The mean follow-up was 40 months (7–55months); 7 patients died of local tumour or distant progression. Three patients are still alive with 2 of them disease free. Conclusion: In selected cases, the RFA of pelvic recurrent rectal cancer can be considered a feasible and effective treatment in the control of pain and in the stabilisation of recidivism.

Radiofrequency ablation of coronary sinus-dependent atrial flutter guided by fractionated mid-diastolic coronary sinus potentials

BackgroundThe efficacy of radiofrequency (RF) ablation of an uncommon coronary sinus (CS)-dependent atrial flutter (AFL) was evaluated using conventional electrophysiological criteria in a highly selected subset of patients with typical and atypical AFL.MethodsFourteen patients with atrial flutter (11 males, mean age 69 ± 9 years) without previous right or left atrial RF ablation were included. Heart disease was present in eight patients. Baseline ECG suggested typical AFL in 12 patients and atypical AFL in two. Mean AFL cycle length was 324 ± 64 ms at the time of RF ablation in the CS. Lateral right atrium activation was counterclockwise (CCW) in 13 patients and clockwise in one. CS activation was CCW in all. Criteria for CS ablation included the presence of CS mid-diastolic fractionated atrial potentials (APs) associated with concealed entrainment with a postpacing interval within 20 ms. Success was defined as termination of AFL and subsequent noninducibility.ResultsThe initial target for ablation was the cavotricuspid isthmus (CTI) in 11 patients and the CS with further CTI ablation in three. AP duration at the CS target site was 122 ± 33 ms, spanning 40 ± 12% of the AFL cycle length. CS ablation site was located 1–4 cm from the CS ostium. Ablation was successful in all patients. Mean time to AFL termination during CS ablation was 39 ± 52 s (<20 s in eight patients). No recurrence of ablated arrhythmia occurred during a follow-up of 18 ± 8 months.ConclusionsThe CS musculature is a critical part of some AFL circuits in patients with typical and atypical AFL. AFL can be terminated in patients with CS or CTI/CS AFL reentrant circuits by targeting CS mid-diastolic fragmented APs.

Electrocardiographic differentiation of common type atrioventricular nodal reentrant tachycardia from atrioventricular reciprocating tachycardia via a concealed accessory pathway

Objective — The present study aimed to evaluate the diagnostic value of specific ECG markers in the differentiation of common type atrioventricular nodal reentrant tachycardia (AVNRT) and atrioventricular reentrant tachycardia (AVRT) via a concealed accessory pathway.Methods — One hundred and ten ECGs with paroxysmal narrow QRS complex, short RP tachycardia were evaluated. Subjects with overt ventricular pre-excitation during sinus rhythm were excluded from the study. The mechanism of arrhythmia was established during the electrophysiological study and confirmed by the efficacy of radiofrequency ablation.Results — Of the 110 patients, 74 displayed common type AVNRT and 36 AVRT. Predictors of AVNRT were the presence of pseudo r’-waves in lead V1 [sensitivity 39.19%; specificity 97.14%; positive predictive value (PPV) 96.67%; negative predictive value (NPV) 43.04%] and pseudo S-waves in inferior leads (sensitivity 28.38%; specificity 94.29%; PPV 91.30%; NPV 38.37%). In the setting of visible P-waves, an RP interval ≤ 90 ms favoured the diagnosis of AVNRT (sensitivity 57.14%; specificity 80.65%). Predictors of AVRT were QRS alternans (sensitivity 50%; specificity 89.19%; PPV 69.23%; NPV 78.57%) as well as ST-segment alterations during tachycardia. The overall sensitivity, specificity, PPV and NPV of ST-segment depression for discriminating AVRT from AVNRT were 97.22%, 58.11%, 53.03%, 97.73%, respectively. Similarly, the sensitivity, specificity, PPV and NPV of ST-segment elevation in lead aVR were 94.44%, 58.11%, 52.31%, and 95.56%, respectively. Multiple logistic regression analysis showed that ST-segment depression [(odds ratio (OR): 12.67, 95% confidence interval (CI): 1.77-90.81, P = 0.011)] and QRS alternans (OR: 9.43, 95% CI: 1.38-64.37, P = 0.022) displayed the highest predictive ability favouring the diagnosis of AVRT.Conclusions — Twelve-lead ECG parameters may help to differentiate the mechanism of supraventricular tachycardia prior to the ablation procedure.

Thermal ablation produced using a surgical toroidal high-intensity focused ultrasound device is independent from hepatic inflow occlusion

In the liver, the efficacy of radiofrequency or high-intensity focused ultrasound (HIFU) ablation is impaired by blood perfusion. This can be overcome by hepatic inflow occlusion. Here we report the in vivo evaluation of ablations performed in the liver using a surgical toroidal HIFU device used during an open procedure with and without hepatic inflow occlusion. The HIFU device was composed of 256 toroidal-shaped emitters working at 3 MHz and an integrated ultrasound imaging probe working at 7.5 MHz. Using an intermittent Pringle maneuver (IPM), thermal ablations were created in three pigs with hepatic inflow occlusion (IPM group) and in three pigs with normal perfusion (NoIPM group). The ablations were studied on sonograms, macroscopically and microscopically 14 days after the treatment. In the NoIPM group, the average coagulated volume obtained after a 40 s exposure was 7.4 ± 3.8 cm3 (2.2–16.6). In the IPM group, the average ablated volume was 6.3 ± 2.9 cm3 (2.6–12.1). There was no significant difference between the two groups in terms of ablated volume (p = 0.25), diameter (p = 0.37) or depth (p = 0.61). Therefore, a toroidal-shaped HIFU device allows treatment in the liver that can be considered as independent from hepatic inflow occlusion.

Hepatocellular Carcinoma With Cirrhosis: Are Patients With Neoplastic Main Portal Vein Invasion Eligible for Percutaneous Radiofrequency Ablation of Both the Nodule and the Portal Venous Tumor Thrombus?

The purpose of this study was to examine the results of percutaneous radiofrequency ablation of both medium-sized hepatocellular carcinoma (HCC) and the accompanying main portal venous tumor thrombus in patients with cirrhosis. From January 2005 to January 2008, among 1,837 consecutively registered patients with HCC seen at our institution, 412 had HCC and portal venous invasion; 27 of the 412 had a single HCC nodule accompanied by main portal venous tumor thrombus. Thirteen patients (10 men, three women; mean age, 70 years; range, 66-74 years) with 13 HCC nodules 3.7-5 cm in diameter extending into the main portal trunk underwent percutaneous radiofrequency ablation. Fourteen matched patients (10 men, four women; mean age, 69 years; range, 67-73 years) with 14 HCC nodules 3.6-4.8 cm in diameter extending into the main portal trunk refused radiofrequency ablation and composed the control group. Diagnosis of main portal venous tumor thrombus was made with fine-needle biopsy in all cases. Radiofrequency ablation was performed first on the main portal venous tumor thrombus and then on the HCC nodule. Efficacy of radiofrequency was defined as complete necrosis of HCC and complete recanalization of the main portal trunk and its branches. HCC necrosis was evaluated with enhanced CT. Recanalization of portal vessels was analyzed with color Doppler and contrast-enhanced ultrasound. Radiofrequency ablation was performed under ultrasound guidance with a perfused needle electrode. Complete necrosis of the HCC associated with complete recanalization of the main portal vein and its branches was achieved in 10 patients (efficacy, 77%). In the other three patients, necrosis of the HCC ranged from 70% to 90%, and recanalization of the main portal trunk was not complete. No major complications occurred. In three cases, mild to moderate ascites and increased aspartate aminotransferase and alanine aminotransferase levels were found. The follow-up periods ranged from 3 to 36 months among the treated patients and 2 to 10 months among the untreated patients. The cumulative survival rate was 77% 6, 12, and 36 months after procedure in the treated group and 43% and 0% 6 and 12 months after diagnosis in the untreated group (p < 0.0001). All 10 successfully treated patients were alive and the portal system was patent at the end of the follow-up period. All three untreated patients died of progressive disease within 5 months of diagnosis. Radiofrequency ablation can destroy both single intraparenchymal medium-sized HCCs and the accompanying main portal venous tumor thrombus with high efficacy and safety and a low rate of complications.

Vasomodulation of Tumor Blood Flow: Effect on Perfusion and Thermal Ablation Size

Blood flow is a key factor in the efficacy of radiofrequency (RF) ablation treatment of solid tumors. We hypothesized that vasoactive drugs can modulate tumor blood flow and thereby improve the outcome of this thermal ablation approach. To verify this hypothesis, we measured the tumor perfusion changes in response to phenylephrine (PE) and hydralazine (HYZ) using a CT perfusion method in a rat subcutaneous tumor model. The coagulation sizes induced by RF ablation alone, RF ablation with PE and RF ablation with HYZ were compared. Results demonstrated that HYZ produced a marked decrease in entire tumor and tumor rim blood flow of 31.1 and 29.1%; while PE insignificantly change tumor blood flow (5.1% decrease in whole tumor and 6.0% decrease in tumor rim). A markedly greater coagulation area (0.59 cm2 +/- 0.24) was observed when HYZ was administered before RF ablation. No difference was noted in the coagulation area induced by RF ablation alone or the combination of PE injection followed by RF ablation (0.29 cm2 +/- 0.13 vs. 0.30 cm2 +/- 0.18). Results suggest that HYZ decreases subcutaneous tumor blood flow and enhances the coagulation size induced by RF ablation. PE has little influence on tumor blood flow and does not improve ablation.