Fulguration Research Articles

Abstract 17376: Novel Non-contrast MRI Technique for Visualization of Ablation Lesions

Introduction: Late gadolinium enhanced MRI (LGE-MRI) is widely used to assess RF ablation lesions. However, this technique requires contrast injection and lesion visibility changes with time after injection. Non-contrast T1-weighted (T1w) MRI is only applicable to reliably visualize acute (< 7 days) RF lesions. Hypothesis: T2*-weighted MRI can be used to visualize ablation lesions. Methods: Novel non-contrast MRI technique for sub-acute (> 7 days) lesion visualization has been developed. This T2*-weighted technique exploits the difference in susceptibility between normal and ablated myocardium. Transformation of hemoglobin from blood vessels damaged during ablation into hemosiderin reduces T2* of ablated tissues. To validate the proposed technique RF ablations were performed in 3 canines using ThermoCool catheter (Biosense Webster) at 30 Watts for 30 seconds. Imaging studies were performed on a 3T MRI scanner (Verio, Siemens) at 0, 1, 4, and 8 weeks post-ablation. Scan protocol included T1w, T2*, and LGE scans with resolution of 1.25x1.25x2.5 mm. Results: Representative T1w, T2*, and LGE images are shown in Figure 1. All RF lesions (n=13) were readily detectable on non-contrast T1w images acquired acutely (Fig. 1a). Lesion visibility in T1w was drastically reduced 1 week post-ablation (Fig. 1b). Visibility of the lesions in T2* images improves with time after ablation (Fig. 1c-e). Lesions have hypointense boundaries in T2* images acquired 1 and 4 weeks post-ablation. Whole lesions are hypointense in T2* images acquired 8 weeks post-ablation. Strong correlation (R2=0.9747) between lesions volumes estimated from LGE and T2* acquired 8 weeks post-ablation was found (Fig. 2). Conclusions: Non-contrast T2* technique for visualization of RF ablations has been developed and validated. The technique can be used to detect RF lesions as early as a week post-ablation. T2* contrast of the lesions improves with time after ablation as amount of hemosiderin increases.

Abstract 16028: Contrast Enhancement Dynamics of Radiofrequency Ablation Lesions

Introduction: Late gadolinium enhanced MRI (LGE-MRI) done acutely after ablation shows a central area of no-reflow that enhances slowly. The dynamics and predictive value of this region to chronic lesion volume is unknown. Methods: RF lesions were created in a canine ventricle model using a 4 mm irrigated tip catheter. 3D LGE-MRI images were acquired in a 3T (Verio, Siemens) MR scanner (1.25 x 1.25 x 2.5 mm 3 ) at weeks 0, 1, 2, and 4 post ablation at multiple time points after contrast injection (Multihance, 0.15 mmol/Kg). The central no-flow volumes in MRI were normalized to the histological volumes and this ratio was compared across multiple post-contrast injection times. Results: The number of lesions analyzed was 33, 27, 11 and 20 at week 0, 1, 2 and 4, respectively in four animals. Histological volumes had a mean of 99±52 mm 3 (range 32-220 mm 3 ). The initial MRI done within five mins of contrast injection had average no reflow volumes of 330±170 mm 3 for week 0, 270±170 mm 3 at week 1, 120±100 mm 3 at week 2, and 50±46 mm 3 at week 4. The normalized no reflow volumes (normalized to chronic histological volume) for the initial MRI was 4.28±1.44 at week 0, 3.40±1.15 at week 1, 1.94±0.68 at week 2, and 0.65±0.42 at week 4. Based on a logarithmic fit to the decay in volume, the no reflow volume equaled the final histological volume 26.6 mins after contrast injection on day 0, 30.9 mins on week 1, 8.2 mins on week 2 and 0.3 mins after week 4. By one month after ablation, the no-reflow was negligible and the final lesion completely enhanced immediately after contrast injection. Conclusions: The no-reflow volume declines exponentially acutely after ablation and results in an accurate assessment of final lesion volume 26 to 30 minutes after contrast injection up to one week post - ablation. With tissue remodeling, the no reflow area enhances faster such that one month after ablation, lesions enhance completely immediately following contrast injection.

Impact of Lesion Placement on Efficacy and Safety of Catheter-Based Radiofrequency Renal Denervation

BackgroundInsufficient procedural efficacy has been proposed to explain nonresponse to renal denervation (RDN). ObjectivesThe aim of this study was to examine the impact of different patterns of lesion placements on the efficacy and consistency of catheter-based radiofrequency RDN in pigs. MethodsThe impact of increasing number of lesions versus location of RDN was investigated in a porcine model (Group 1; n = 51). The effect of treating the main artery, the branches, and the 2 combined was compared in Group 2 (n = 48). The durability of response and safety of combined treatment of the main artery plus branches was examined in Group 3 (n = 16). Renal norepinephrine (NE) tissue content and renal cortical axon density were assessed. ResultsIncreasing the number of RF lesions (4, 8, and 12) in the main renal artery was not sufficient to yield a clear dose-response relationship on NE content and axon density. In contrast, targeted treatment of the renal artery branches or distal segment of the main renal artery resulted in markedly less variability of response and significantly greater reduction of both NE and axon density than conventional treatment of only the main renal artery. Combination treatment (main artery plus branches) produced the greatest change in renal NE and axon density with the least heterogeneity. The changes were durable through 28 days post-treatment. ConclusionsThese data provide the rationale for investigation of an optimized approach for RDN in future clinical studies. This may have profound implications for the clinical application of RDN, as this approach may not only achieve greater reductions in sympathetic activity but also reduce treatment effect variability.

Treatment of chronic lumbosacral radicular pain using adjuvant pulsed radiofrequency: a randomized controlled study.

The objective of this study was to determine the effects of combining pulsed radiofrequency (PRF) treatment and transforaminal epidural injection (TFEI) to treat patients with chronic refractory lumbar radicular pain caused by lumbar spinal stenosis. Randomized control trial. Interventional pain management practice. Sixty-two patients were assigned to the study groups (PRF group = 31; control group = 31). Under fluoroscopic guidance, the RF needle was positioned close to the lumbar dorsal root ganglion. The PRF group received 3 cycles of PRF treatment, and sensory stimulation without RF lesioning was applied to the control group. After PRF or sham lesioning, a local anesthetic with steroid was injected. The primary outcome of a successful response was defined as: 1) ≥50% or 4-point pain reduction in the numerical rating scale (NRS) without an increase in the Oswestry disability index (ODI) or medication quantification scale (MQS), or mean score <4 in the global perceived effect (GPE) scale; or 2) ≥30% or 2-point pain reduction in NRS with a simultaneous decrease in ODI, MQS, or ≥6 points in the GPE scale. The number of patients with successful treatment results was higher in the PRF group at 2 months (P = 0.032) and 3 months (P = 0.018). No significant differences were observed in terms of the secondary outcome variables between the 2 groups. The TFEI provided significant short-term pain relief and PRF can be applied in conjunction with TFEI to achieve higher treatment efficacy compared with TFEI alone.

Intracardiac myocardial elastography in canines and humans in vivo.

Intracardiac echocardiography (ICE) is a useful imaging modality which is used during RF ablation procedures to identify anatomical structures. Utilizing ICE in conjunction with myocardial elastography (ME) can provide additional information on the mechanical properties of cardiac tissue and provide information on mechanical changes caused by ablation. The objective of this study was to demonstrate that ICE can be used at high frame rate using a diverging beam transmit sequence to image myocardial strain and differentiate myocardial tissue properties before, during, and after ablation for a clinical ablation procedure. In this feasibility study, three normal canines and eight patients with atrial fibrillation (AF) were studied in vivo. A 5.8-MHz ICE transducer was used to image the heart with a diverging beam transmit method achieving 1200 frames per second (fps). Cumulative axial displacement estimation was performed using 1-D cross-correlation with a window size of 2.7 mm and 95% overlap. Axial cumulative strains were estimated in the left atrium (LA) and right atrium (RA) using a least-squares estimator with a kernel of 2 mm on the axial displacements. In the canine case, radial thickening was detected in the lateral wall and in the interatrial septum during LA emptying. For AF patients, the mean absolute strain in the ablated region was lower (6.7 ± 3.1%) than before the ablation (17.4 ± 9.3%) in LA at the end of the LA emptying phase. In the cavotricuspid isthmus (CTI) region, mean absolute strain magnitude at the end of the RA emptying phase was found to be higher during ablation (43.0 ± 18.1%) compared with after ablation (33.7 ± 15.8%). Myocardial strains in the LA of an AF patient were approximately 2.6 times lower in the ablated region than before ablation. This initial feasibility indicates that ME can be used as a new imaging modality in conjunction with ICE in RF ablation guidance and lesion monitoring.

Experience and modification of percutaneous nephrolithotomy for caliceal diverticular calculi

Objective To summary our experiences in percutaneous nephrolithotomy for treating the caliceal diverticular calculi and postoperative outcome with technical modification.Methods A retrospective review was performed on 34 patients with caliceal diverticular calculi who underwent percutaneous nephrolithotomy between January 2009 and June 2013.The patients were divided into 2 groups.In group A (1 1patients),stones were removed and diverticular neck was incised.In group B (23 patients),fulguration of diverticular wall was performed after the stone removal and diverticular neck incision.Group A had 11 cases including 4 male and 7 female with average age (36.7± 16.0) years.Mean size of stone was (1.8±0.4) cm.Mean maximum diameter of diverticulum was (2.3±0.5) cm.Group B had 23 cases including 10 male and 13 female with average age (40.1±12.0) years.Mean size of stone was (1.9±0.6) cm.Mean maximum diameter of diverticulum was (2.3±0.8) cm.There were no significant difference in stone size and maximum diameter of diverticulum within two groups (P＞0.05).The following parameters such as operative time,drop in hemoglobin,stone clearance,complication rate and ablation rate of diverticulum were compared between two groups.Results In group A,average operative time was (62.7±11.7) min.Mean hemoglobin dropping was (12.0t9.7) g/L.Stone clearance rate was 90.9％ (10/11) and overall complications rate was 18.2％ (2/11).The ablation rate of diverticulum was 63.6％ (7/11).In group B,average operative time was (76.3±21.6) min.Mean Hemoglobin reducing was (12.9±16.7) g/L.Stone clearance rate was 91.3％(21/23) and overall complication rate was 21.7％.The ablation rate of diverticulum was 91.3％ (21/23).There was no significant difference in stone clearance and complication rate between two groups.It seemed that the operativc timc in group B was longer than that in group A.However,no significant difference was found (P＞0.05).The ablation rate of diverticulum in group B was significantly higher than that in group A (P＜0.05).Conclusion In percutaneous nephrolithotomy treatment for caliceal diverticular calculi,fulguration to diverticular wall is an effective method to achieve diverticular obliteration and reduce possibility of stone recurrence. Key words: Caliceal diverticular calculi; Percutaneous nephrolithotomy; Diverticulum fulguration

The experience of diagnosis and treatment of primary ureteral polyps：a report of 27 cases

Objective To explore the diagnosis ,treatment methods and clinical features of primary ureteral polyps.Methods Clinical data of 27 cases with primary ureteral polyps were analyzed retrospectively .The clinical features and treatment of this disease were analyzed .Results 7 cases were treated with polypectomy ,10 cases with basement fulguration by ureteroscopy operation or polyps-removing by ureter forceps ,4 cases with distal ureter resec-tion and termino-terminal anastomosis ,4 cases with lesions ureter resection and bilateral ureteric reimplantaion and 2 cases with nephrectomy due to nonfunctioning kidney .All cases were confirmed to be primary ureter polyp by pathology.All cases were followed up for 6-12 months with no recurrence and canceration ,only 1 case had ureteral stenosis.Conclusion Primary ureteral polyps is a benign disease with rare malignancy .The primary and effective treatment method is surgery which has few complications and good effect . Key words: Ureter polyps ; Surgery ; Ureteroscopy

47 * Oesophageal temperature probe during atrial fibrillation radiofrequency catheter ablation: friend or foe?

Introduction: Oesophageal temperature monitoring during atrial fibrillation (AF) ablation is one of the suggested strategies to prevent atrioesophageal fistula. It is not known whether temperature alerts that lead to early termination of RF and/or reduction in power prevent lesion durability and promote acute and chronic pulmonary vein (PV) reconnection. Methods: At our institution all AF ablations performed under general anaesthesia have oesophageal temperature monitoring using the 5-pole Sensitherm (St Jude Medical). The probe can be visualised on the 3D electroanatomic Velocity geometry. During the ablation procedure any sites that cause a temperature rise of >39oC and premature cessation of RF and/or reduction in power (20-25W) during wide area encirclement are labelled on the geometry in a different colour from standard, complete and uninterrupted RF lesions (30-40W, minimum 15-20 seconds in a stable position). The study population consisted of all patients (pts) returning for a 1st redo ablation from November 2012 to May 2014. The site(s) of PV reconnection as determined by multipolar catheter mapping and successful re-isolation RF lesions were labelled on the 3D geometry and compared with lesion markers from the initial procedure. For both the initial and redo procedure the temperature probe position relative to the PV veins and posterior wall was recorded as left, mid or right segment. Results: There were 54 pts undergoing 1st redo procedures: 36 males, mean age 68±9,22 (41%) paroxysmal and 32 (59%) persistent AF. At the time of the index procedure, the probe was left-sided in 22 pts (41%), right-sided in 20 pts (37%) and in the mid-wall segment in 12 pts (22%). An oesophageal shift (change in segment) was found in 10 pts at time of the follow up procedure. Thirty pts (56%) had at least one temperature alert during the index procedure, affecting 46 PVs (21% of a total of 216 PVs). The median length of lesions causing alerts was 21 (16-26) mm for LPVs and 18 (15-25) mm for RPVs. The distribution of temperature alerts at the initial procedure was LSPV 24%, LIPV 33%, RSPV 13%, RIPV 30%. In 12 patients there were 23 PVs that had acute reconnection requiring further ablation. There was no correlation between acute PV reconnection and temperature alerts (p=0.5). At the time of the redo procedure, 103 PVs were found to be reconnected in 44 patients. No correlation was found between the occurrence of temperature alerts at the initial procedure and chronic reconnection in the associated pulmonary vein (p=0.27). Conclusion: Just over half of patients undergoing PV isolation will have an oesophageal temperature alert. Reducing power and RF duration does not increase or decrease the incidence of subsequent PV reconnection. Temperature probe-guided ablation may therefore increase safety without compromising ablation efficacy.

Effect of polysaccharide nucleic acid fraction of bacillus Calmette-Guerin on CD4+CD25+Foxp3+ regulatory T cells in peripheral blood of patients with condyloma acuminatum

Objective To evaluate the effect of polysaccharide nucleic acid fraction of bacillus Calmette-Guerin (BCG-PSN) on peripheral blood CD4+CD25+Foxp3+ regulatory T (Treg) cells in patients with condyloma acuminatum (CA).Methods Forty-two patients with first onset of CA were randomly assigned to receive either injection of BCG-PSN (0.35 mg every other day for 3 months) after fulguration (combination group,26 patients),or fulguration only (fulguration group,16 patients).Venous blood samples were obtained from all the patients at the initial visit and three months after the beginning of treatment,as well as from 30 healthy checkup examinees.The percentage of peripheral Treg cells in CD4+ T lymphocytes was determined by flow cytometry.The recurrence of CA was evaluated during the three months after the beginning of treatment.Results The percentage of peripheral Treg cells in CD4+ T lymphocytes was significantly higher in patients with CA than in the controls (8.31％ ± 1.24％ vs.5.15％ ± 0.72％,P ＜ 0.01),and in patients with clinical recurrence of CA than in those without (9.34％ ± 0.72％ vs.7.45％ ± 0.85％,P ＜ 0.01).The recurrence rate was significantly lower in the combination group than in the fulguration group (30.77％ vs.68.75％,P ＜ 0.05).After three months of treatment,the combination group showed lower percentage of Treg cells in CD4+ T cells compared with the fulguration group (5.87％ ± 1.05％ vs.6.60％ ± 0.75％,P ＜ 0.05).Conclusions The percentage of Treg cells has a close relationship with the progression of CA,i.e.,the higher the percentage,the more frequent the relapse.BCG-PSN may enhance the antiviral immune response in patients with CA and improve their prognosis by reducing the number of Treg cells. Key words: Condylomata acuminata; BCG-PSN; CD4-positive T-lymphocytes; FoxP3

Curative effect and nursing care of ALA-PDT combined with high-frequency electrofulguration for basal cell carcinoma

Objectives To explore the clinical efficacy and nursing care of 5-aminolevulinic acidphotodynamic therapy (ALA-PDT) combined with high-frequency flectrofulguration for basal cell carcinoma (BCC).Methods 40 patients received ALA-PDT and high-frequency electrofulguration basing on individual lesion.They all received good nursing care and guidance.The completely remitted patients were followed up for 6 months.Results After 5-15 times of treatment and good nursing care,31 patients (77.5％) got complete remission,4 (10.0％) partial remission,and 5 (12.5％) invalid.The total effective rate was 87.5％.29 patients (72.5％) were satisfied with the cosmetic results,4 (10.0％) moderately satisfied,and 7 (17.5％) dissatisfied.6 months followed-up showed that 4 patients(12.9％) recurred in the 31 complete remission patients.No patient got infection.No one' s wound healed poorly.Conclusions ALA-PDT combined with high-frequency electrofulguration in the treatment of BCC is quite effective.Coupled with good nursing measures,it can improve the therapeutic effect and increase the patients' satisfaction with treatment. Key words: ALA-PDT; High-frequency electrofulguration; Basal cell carcinoma; Clinical efficacy; Nursing care

Observation of the effects of 5-aminolevulinic acid photodynamic therapy combined with fulguration in treating perianal condyloma

Objective To evaluate the relapse rate and the effect of 5-aminolevulinic acid photodynamic therapy(ALA-PDT) combined with fulguration in the treatment of perianal genital warts.Methods 67 patients with perianal genital warts were randomly divided into the three groups.22 cases in the fulguration and ALA-PDT treatment group performed the ALA-PDT treatment immediately after removal of dominant wart by fulguration,once a week,treatment for 3-4 times.22 cases in the ALA-PDT treatment group only underwent ALA-PDT treatment,once a week,treatment for one month.23 cases in the fulguration group were given the traditional fulguration methods one by one electrocautery fulguration gasification treatment for all skin lesions,a weekly batch treatment,treatment for a month.Follow-up six months after the last treatment to determine efficacy and recurrence rate.Results The cure rate of combined treatment group was 90.9％ (20/22),and recurrence rate was 9.1％ (2/22) ;cure rate of photodynamic group was 54.5％ (12/22),and its recurrence rate was 22.7％ (5/22) ; cure rate of fulguration group was 39.1％ (9/23),and the recurrence rate was 43.5％ (10/23).There were statistically significant differences in the cure rate and relapse rate between combination therapy group and electrocautery treatment group (P =0.000,P =0.017).Conclusion The fulguration combined with ALA-PDT in the treatment of perianal genital warts has high cure rate,low recurrence rate,and less side effects. Key words: Condylomata acuminata ; 5-aminolevulinic acid; Photodynamic therapy ; Fulguration

Mechanisms of Pulmonary Vein Reconnection After Radiofrequency Ablation of Atrial Fibrillation: The Deterministic Role of Contact Force and Interlesion Distance

Pulmonary vein reconnection (PVR) is an important cause of AF recurrence after ablation. With the advent of force sensing catheters, catheter-tissue contact can be determined quantitatively. Since contact force (CF) plays a major role in determining the characteristics of RF lesion, we prospectively assessed the mechanisms of PVR with regard to catheter-contact and lesion distances in patients undergoing AF ablation. Forty symptomatic AF patients underwent wide circumferential PV isolation (PVI) with SmartTouch™ CF catheter. The exact locations of acute PVI and spontaneous or adenosine-provoked PVR were annotated on CARTO. One thousand nine hundred and twenty-six RF lesions isolated 153PVs. PVR occurred in 35 (23%)PVs: 22 (63%) adenosine-provoked and 13 (37%) spontaneous. CF was significantly lower at PVR versus PVI sites for RF lesions within 6mm from these sites: mean CF 5 versus 11g (P< 0.0001) and force-time integral (FTI) 225 versus 415gs (P< 0.0001); 86% of PVR occurred with a mean CF< 10g (FTI< 400gs); and the remaining 14% occurred at ablation sites with a long interlesion distance (≥5mm) despite mean CF≥ 10 g. Eighty percent of PVR sites were located anteriorly. There were no significant differences in regard to arrhythmia freedom between the patients without (69%) versus with PVR (67%; P= 1.0). Acutely durable PVI can be achieved when RF lesions are delivered with a mean CF≥ 10g and an interlesion distance<5mm. The majority of PVR occur anteriorly due to inadequate CF or long interlesion distances.

Endoscopically guided foraminal and dorsal rhizotomy for chronic axial back pain based on cadaver and endoscopically visualized anatomic study.

Background Conventional fluoroscopically guided continuous radiofrequency (CRF) and pulsed Radiofrequency (PRF) lesioning of the medial branch, dorsal ramus, a standard technique to treat facet pain, is compared to an endoscopic visually guided technique. The endoscopic technique (Figure 1) is designed to ablate a larger area of the transverse process where the medial branch crosses to innervate the facet. Endoscopically guided visualization provides confirmation of nerve ablation or transection in the most common location of the branches of the dorsal ramus innervating the facet joint. Materials and Method A retrospective non randomized study of 50 initial patients assessed the efficacy of endoscopic rhizotomy. Patients with lumbar spondylosis and facet arthrosis who had at least 50% pain relief by medial branch blocks met the inclusion criteria for the visualized, surgically directed endoscopic technique. A specially designed cannula and endoscope (Richard Wolf, GmBh) (Figure 2) was developed specifically for this purpose. After completion of the initial 50 patient pilot study in 2005, utilizing a low-temperature, ultra-high frequency (1.7-4.0 MHz) bipolar energy radiofrequency source (Elliquence Int, Hewlett, NY) that demonstrated efficacy, 400 subsequent patients were added to this retrospective study by May 2013. The surgical technique refinement was guided by cadaveric variations observed from additional cadaver dissections (Figure 3) and endoscopic visualization of foraminal nerves that revealed variable locations of the dorsal ramus, including the medial branch. The anatomic variations supported a need for visualized rhizotomy. The inclusion criteria also involved increasing the percentage of back pain relief from medial branch blocks to a base of 75% estimated improvement in order to overcome the variable subjectiveness of a 50% improvement threshold that served to disappoint a small percentage of patients who overestimated the reported 50% improvement in hopes that they would qualify for the endoscopic guided procedure. Results At one year follow-up in the initial study design, VAS improved 6.2-2.5, and ODI 48-28. All patients had VAS improvement equal or greater than injection. The results remained constant with additional surgical cases that continued to improve when technique and visualized rhizotomy allowed for greater surgical exploration and ablation of the targeted zone where more than just the medial branch could be ablated. Approximately 10 percent of the patients returned at one and two year follow-up with mild recurrence of their axial back pain, but none to the original level of pain. Additional rhizotomy of the upper lumbar facets provided additional relief in selected patients. Conclusions / level of evidence 3 The cadaver studies demonstrated considerable variability in the location of the medial and lateral branches of the dorsal ramus. Variability was most common cephalad to L3-4. The dorsal ramus and its nerve branches can also be visualized in the foramen ventral to the intertransverse ligament. Neuromas and entrapment of the dorsal ramus has been identified endoscopically, and confirmed by H and E slides (Figure 4). In the upper lumbar spine, we were not able to find the medial branch to the facets consistently at same location. The nerve to the facet joint did not always cross the transverse process. Some branches enter the facet joint before crossing the transverse process adjacent to the tip of the SAP (Figure 5). The nerve can be mistaken for a furcal nerve or foraminal ligament. Nerve Ablation at above L3-4 levels may require lesioning of the dorsal ramus or targeting the nerve innervation on the facet wall, pedicle or capsule. Clinical Relevance Endoscopically guided facet rhizotomy provides more consistent ablation of the medial and lateral branches of the lumbar dorsal ramus compared to radiographically guided pulsed radiofrequency. The variations in the location of facet innervation can explain the variability of clinical results in fluoroscopically guided RF lesioning. This observation dictates a need for visually guided MIS procedure for best results.

Characterization of Catheter–Tissue Contact Force During Epicardial Radiofrequency Ablation in an Ovine Model

Contact force (CF) during radiofrequency ablation (RFA) is an important determinant of endocardial lesion size with limited data on epicardial RFA and CF. We evaluated CF characteristics using irrigated RFA on the epicardium in an ovine model. In 12 sheep, a 7-F irrigated RFA catheter with CF sensor was introduced via a pericardial incision onto/in parallel with ventricular epicardium. RFA (30 W per 30 second duration) was applied at 5g, 10g, 20g, 40g, and 70g: (1) over left and right ventricular myocardium with or without fat, (2) either directly over or adjacent to a coronary artery, or directly over the phrenic nerve. Force-time integral, lesion dimensions, and coronary artery/phrenic nerve injury were recorded. Lesion size, volume, and force-time integral progressively increased with higher CF (P<0.05). Steam pops occurred with high CF. Epicardial fat had an attenuating effect on RF penetration into myocardium (P<0.05); however, myocardial RF lesions could be created at sites with >3.5 mm epicardial fat. At sites with epicardial fat, each 10g increment in CF led to a 0.6 mm increase in lesion depth, whereas each 1 mm of fat reduced lesion depth into underlying myocardium by 0.7 mm. Extent of acute coronary injury with direct and indirect RFA and phrenic nerve palsy occurrence was proportional to CF. CF is a determinant of epicardial RF lesion size, steam pops, acute coronary artery injury, and phrenic nerve injury. Although epicardial fat limits lesion size, RFA with high CF can produce small myocardial RF lesions at sites of thick epicardial fat.

Indications for Repeat Diagnostic Medial Branch Nerve Blocks Following a Failed First Medial Branch Nerve Block

No studies have directly measured the false negative rate of medial branch block (MBB) with correlation to medial branch neurotomy (MBN) outcome. We investigated the potential false negative MBB rate and the subsequent MBN outcome on a consecutive audit of all patients undergoing a double MBB protocol. We prospectively collected audit data and retrospectively collected data by phone on 229 consecutive patients undergoing diagnostic MBB. One-hundred-twenty-two patients reporting greater than 50% of subjective pain relief subsequently underwent either MBN or a confirmatory block followed by MBN. A total of 55 patients underwent a second confirmatory MBB and within that group 27.3% (15/55) reported less than 50% relief post initial MBB and 30.9% (17/55) between 50% and 69% relief. We performed an in-depth analysis of these 2 subgroups focusing on the reason a second MBB was performed despite a “negative” or “indeterminant” first MBB. We divided the “negative” responders to the first MBB into those reporting &lt; 50% relief (Group 1) and those reporting between 50% and 69% relief (Group 2). We calculated a potential 46.7% false negative rate in Group 1 and 47.1% false negative in Group 2; however, the false negative results in Group 1 were predominately in those patients reporting delayed relief of pain and those re-blocked greater than 2 years after the first MBB. The success rate in all patients undergoing MBN was 87% compared to the 75% relief in the false negative groups with no statistically significant difference. In summary, the false negative rate for patients reporting less than 50% relief post MBB is probably less than 20% although there is a high “apparent negative” responds in patients reporting delayed relief or in those who had a second block 2 or more years post initial MBB. Patients reporting between 50 and 69% pain relief have a false negative response rate of 47.1% and should be considered for a confirmatory block. Key words: Facet rhizotomy, zygapophyseal joint, low back pain, chronic pain, facet joint, radiofrequency neurotomy, medial branch block, medial branch neurotomy

Percutaneous radiofrequency thoracic sympathectomy for refractory arrhythmogenic storms: first in man study of six cases

Background: Catheter ablation has been shown to be effective in the treatment of scar-related ventricular tachycardia (VT). In limited number of patients ablation therapy failed to stop all incessant or unstable VTs. Several case reports and series have described the role of thoracic sympathectomy (VATS) in the treatment of refractory VTs. Method: We report three cases of patients with arrhythmic storm and nearly incessant refractory VTs who were treated with a percutaneous radiofrequency T2 and T3 sympathectomy on the left side. Results: 1) 42-y-old man with severe dilation CMP (LVEF 20%), after ICD storming. Both endocardial and epicardial radiofrequency and later alcohol ablations of the arrhythmogenic substrate were performed with insufficient effect. 2) 58-y-old man with ARVD was admit with arrhythmogenic storm. Both endocardial and epicardial RF ablations didn't stop recurrent VTs. 3) 62-y-old man post MI arrhythmic storm with several ICD shocks, complex catheter ablation failed to lessen the number of VT epizodes. 4) 40 y-old man post MI after CABG with ICD storming and unsuccessful catheter ablation 5) 51 y-old man postmyocarditis CMP with arrhythmic storm and repeated epicardial/endocardial ablation 6) 89 y-old man with ischemic CMP with severely depressed LV function (LV EF 15%), BiV ICD with storming and three catheter ablations failed to stabilised the rhythm The patients were indicated for a local anaesthetic block of the left stellate ganglion under real-time ultrasound guidance. Following the block both heart rate and blood pressure droped more than ten percent and patient did not experience any significant ventricular tachycardias for more than a week. He was then scheduled for the RF T2 and T3 left thoracic sympathectomy which was performed in supine position under local anaesthesia and mild sedation. A multi-planar fluoroscopy was used for a guidance. Six RF lesions (3 for each needle, medial, cranial and caudad rotation of the curved tip) were used, at the temperature of 70°C, 90 sec each. 0.5ml of 6% phenol was applied at the end of procedure into each needle to complete the sympathicolysis. Patients were not experienced with any ICD shocks since the sympathetic denervation., in two repeated ATPs terminated VTs. Conclusion: RF upper thoracic sympathectomy may become a considerable option for patients with refractory ventricular arrthythmias not responding on medical and electroinvasive treatment.

The Determinants of Successful RF Ablation - Is Measurement of Tissue Contact the Next Step?

The assessment of tissue contact is an area undergoing much research as a means of improving the outcomes of cardiac radiofrequency ablation. This review provides an overview of RF ablation with specific reference to the relevance of good tissue contact to adequate RF lesion formation. An up-to-date review of the clinical evidence is provided, and recent patents of novel contact-sensing technologies in the field of cardiac RF ablation are presented.

Verbal Episodic Memory Impairment in Schizophrenia: A Comparison with Frontal Lobe Lesion Patients

Schizophrenia (SCZ)-related verbal memory impairment is hypothesized to be mediated, in part, by frontal lobe (FTL) dysfunction. However, little research has contrasted the performance of SCZ patients with that of patients exhibiting circumscribed frontal lesions. The current study compared verbal episodic memory in patients with SCZ and focal FTL lesions (left frontal, LF; right frontal, RF; and bi-frontal, BF) on a four-trial list learning task consisting of three lists of varying semantic organizational structure. Each dependent variable was examined at two levels: scores collapsed across all four trials and learning scores (i.e., trial 4–trial 1). Performance deficits were observed in each patient group across most dependent measures at both levels. Regarding patient group differences, SCZ patients outperformed LF/BF patients (i.e., either learning scores or scores collapsed across trial) on free recall, primacy, primary memory, secondary memory, and subjective organization, whereas they only outperformed RF patients on the semantically blocked list on recency and primary memory. Collectively, these results indicate that the pattern of memory performance is largely similar between patients with SCZ and those with RF lesions. These data support tentative arguments that verbal episodic memory deficits in SCZ may be mediated by frontal dysfunction in the right hemisphere.

Spectral profiles of acute and healed myocardial radiofrequency ablation lesions

A spectral approach to differentiate between acute and healed myocardial lesions was explored. The long‐term goal of these studies is improved treatment of atrial fibrillation using percutaneous RF catheters. The epicardial surface of excised rat hearts was illuminated by continuous wavelength spectrum via an optical fiber coupled to a spectrofluorometer. Emitted, scattered and reflected light was acquired by a high sensitivity CCD camera. Spectra were separated into three groups: unablated tissue, acute and healed RF lesions. Structure of the lesions was confirmed by cytopathology. Spectra between all three groups differed significantly throughout the 300–800nm range. The largest difference was observed in the 300–400nm illumination range accounting for the loss of NADH fluorescence in acute lesions, but not in healed tissue. In the 400–620nm illumination range both acute and healed epicardial lesions exhibited significantly higher intensity compared to control tissue. In the 620–800nm range difference between three groups diminished. The results point to a possibility of in situ visualization of acute and chronic lesions based on the spectral differences in reflected and emitted light. The sensitivity and specificity of lesion identification can be further increased by ratiometry of images acquired at different illumination wavelengths (Supported by the NIH HL095828 &amp; NSF CBET1231549)

Clinical evaluation of a novel 12-hole irrigated tip catheter ablation system for the treatment of typical atrial flutter—results from the Duo FLAIR clinical study

Higher current density at the proximal end of a six-hole catheter is not irrigated and thus could lead to uneven heating and possibly coagulum and charring. This study tested a novel 12-hole irrigated catheter with six additional holes at the proximal end that provides more uniform cooling during atrial flutter (AFL) ablation. A total of 188 patients (28 females, 66 ± 11years) were treated for typical AFL at 22 sites in the USA and Canada using Cool Path Duo at 50W and 45°C at an irrigation rate of 13ml/min. The results were compared to historical data from an AFL study which used a six-hole catheter with similar design. A total of 2,725 RF lesions were applied in 188 patients with a mean RF duration of 18.2 ± 11.7min per procedure. Procedural success was achieved in 96.3% (181 of 188) acutely and 98.3% (173 of 176) patients at 3months. Steam pops occurred in 0.6% of lesions (15 of 2,725) without coagulum or charring… Compared to the six-hole irrigated tip catheter, the Cool Path Duo catheter delivered more power (33.8 ± 5.9 vs. 29.7 ± 5.2W, p < 0.0001) at a lower average tip temperature (34.7 ± 1.5 vs. 37.2 ± 2.1°C, p < 0.0001) with no statistical differences in either 3-month AFL recurrence or complications. Cool Path Duo™ irrigated tip catheter is safe and effective in treating typical AFL. When compared to a six-hole irrigated tip catheter, the Cool Path Duo catheter delivers more power at a lower temperature.