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Introduction: Initial management of traumatic brain injury (TBI) without immediate need for surgical therapy varies across centers. The additional value of routine repeat cranial computerized tomography (CT) to neurological monitoring is controversial. This retrospective study investigates the impact of routine follow-up CT after 6 h (CT6h) in initially conservatively managed TBI on surgical decision making. Furthermore, the impact of coagulopathy on lesion size and progression was examined. Methods: We reviewed charts of patients admitted to our clinic in the time between 1st January 2020 and 30th June 2022 for the ICD10 diagnosis S06.3 (traumatic brain contusion), S06.4 (epidural hematoma), S06.5 (subdural hematoma), and S06.6 (traumatic subarachnoid hemorrhage). Baseline characteristics as well as timing, reason, and consequences of first and second cranial CT, clinical course, lesion size at first and second CT as well as presence and type of coagulopathy (standard laboratory testing and prior medical history) were noted among others. Significance testing was carried out using Student's t-test. The significance level was set to p < 0.005. Results: A total of 213 patients were included, 78 were operated after first CT, 123 underwent clinical and imaging surveillance, and 12 patients were not treated. CT6h did not anticipate imminent neurological deterioration. Early secondary deteriorating patients (9/123, 7.3%) did so before 6 h after admission clustering between 3 and 4 h (6/9, 66.7%). CT6h changed surgical decision making in one case (1/114, < 1%). Nine out of 106 (8.5%) patients managed conservatively after CT6h showed a late secondary clinical deterioration or failure of conservative treatment, eight out of which had stable size of hemorrhage in CT6h. There was no significant difference in lesion size at first CT related to the presence of coagulopathy, antiplatelet agents, or anticoagulant drugs for SDH or contusions. In patients with radiological progression of SDH in combined brain injury (CBI), coagulopathy was associated with a higher increase of lesion size (diameter increase > 6 mm: 11.1% with vs. 2.8% without coagulopathy). This effect was not observed for contusions in CBI (volume increase > 6 ml: 17.4% with vs. 22.7% without coagulopathy). Conclusion: Early routine follow-up CT does neither anticipate imminent neurological deterioration nor impact surgical decision making. A substantial number of patients with initially stable follow-up imaging need delayed surgery due to conservative treatment failure. If patients can be monitored clinically, surgical decision making depends on clinical status. Patients with coagulopathy do not present with larger lesions, but show a higher ratio of drastic increase in SDH in contrast to contusions. [ABSTRACT FROM AUTHOR]

Background: Lesion size is reported to become larger as contact force (CF) increases. However, this has not been systematically evaluated in temperature-guided very high-power short-duration (vHPSD) ablation, which was therefore the purpose of this study. Methods: Radiofrequency applications (90 W/4 s, temperature-control mode) were performed in excised porcine myocardium with four different CFs of 5, 15, 25, and 35 g using QDOT-MICRO™ catheter. Ten lesions for each combination of settings were created, and lesion metrics and steam-pops were compared. Results: A total of 320 lesions were analyzed. Lesion depth, surface area, and volume were smallest for CF of 5 g than for 15, 25, and 35 g (depth: 2.7 mm vs. 2.9 mm, 3.0 mm, 3.15 mm, p < .01; surface area: 38.4 mm² vs. 41.8 mm², 43.3 mm², 41.5 mm², p < .05; volume: 98.2 mm³ vs. 133.3 mm³, 129.4 mm³, 126.8 mm³, p < .01 for all pairs of groups compared to CF = 5 g). However, no significant differences were observed between CFs of 15-35 g. Average power was highest for CF of 5 g, followed by 15, 25, and 35 g (83.2 W vs. 82.1 W vs. 77.1 W vs. 66.1 W, p < .01 for all pairs), reflecting the higher incidence of temperature-guided power titration with greater CFs (5 g:8.8% vs. 15 g:52.5% vs. 25 g:77.5% vs. 35 g:91.2%, p < .01 for all pairs except for 25 g vs. 35 g). The incidence of steam-pops did not significantly differ between four groups (5 g:3.8% vs. 15 g:10% vs. 25 g:6.2% vs. 35 g:2.5%, not significant for all pairs). Conclusions: For vHPSD ablation, lesion size does not become large once the CF reaches 15 g, and the risk of steam-pops may be mitigated through power titration even in high CFs. [ABSTRACT FROM AUTHOR]

Background and aims: The safety evaluation of TactiFlex, a novel contact‐force sensing catheter with a flexible 4‐mm tip irrigated through laser‐cut kerfs, has been ongoing. This study aimed to verify the safety of this type of catheter. Methods: Study 1: Radiofrequency (RF) applications at a range of powers (30–50 W), contact forces (10–20 g), and durations (10–60 s) using perpendicular/parallel catheter orientation with half‐normal (HNS) or normal saline irrigation were compared between TactiFlex (4‐mm tip) and TactiCath (3.5‐mm tip) with temperature‐controlled mode in excised porcine hearts. Study 2: The relation between RF applications using TactiFlex and the incidence of steam‐pops in the real clinical cases were examined. Results: Study‐1: 576 RF lesions were examined. TactiFlex demonstrated a significantly lower risk of steam‐pops (5[1.7%] vs. 59[20.5%], p <.0001). Compared to 3.5‐mm‐tip catheter (TactiCath), 4‐mm‐tip catheter (TactiFlex) produced smaller lesion volume at perpendicular (193[98–554]mm3 vs. 263[139–436]mm3, p <.0001), but relatively similar lesion volume at parallel contact (243[105–443]mm3 vs. 278[180–440]mm3, p =.06). HNS‐irrigation tended to increase the lesion volume in both catheters and to increase the incidence of steam‐pops with TactiCath, but not with TactiFlex. The cut‐off value of %impedance‐drop (= absolute impedance‐drop/initial impedance) of 20% predicted steam‐pops with a sensitivity = 100% and specificity = 89.6% in TactiFlex. Study‐2: 5496 RF applications in 84 patients (51AFs/8ATs/3AVNRTs/4AVRTs/17PVCs/4VTs) using TactiFlex were analyzed. Four steam‐pops (0.07%) in three patients with pericardial effusion were observed (%impedance‐drop = 24%/26%/29%/35%, respectively). The cut‐off value of %impedance‐drop = 20%, derived from ex‐vivo study, showed sensitivity = 100% and specificity = 90.1% in detecting steam‐pops. Conclusion: TactiFlex reduced the risk of steam‐pops than TactiCath. %impedance‐drop ≤ 20% may be reasonable for safely use with a sufficient safety margin. For 4‐mm‐tip catheter, parallel‐contact may be recommended for larger lesion creation. [ABSTRACT FROM AUTHOR]

Background: The influence of power, duration and contact force (CF) on radiofrequency (RF) lesion formation is well known, whereas data on local impedance (LI) and electrode‐tissue‐coverage (ETC) is scarce. The objective was to investigate their effect on lesion formation in an ex vivo model. Methods and Results: An ex vivo model was developed utilizing cross‐sections of porcine heart preparations and a force‐sensing, LI‐measuring catheter. N = 72 lesion were created systematically varying ETC (minor/full), CF (1–5 g, 10–15 g, 20–25 g) and power (20 W, 30 W, 40 W, 50 W). In minor ETC, the distal tip of the catheter was in electric contact with the tissue, in full ETC the whole catheter tip was embedded within the tissue. Lesion size and all parameters were measured once per second (n = 3320). LI correlated strongly with lesion depth (r = −0.742 for ΔLI; r = 0.781 for %LI‐drop). Lesions in full ETC were significantly wider and deeper compared to minor ETC (p <.001) and steam pops were more likely. Baseline LI, ΔLI, and %LI‐drop were significantly higher in full ETC (p <.001). In lesions resulting in steam pops, baseline LI, and ΔLI were significantly higher. The influence of CF on lesion size was higher in minor ETC than in full ETC. Conclusions: ETC is a main determinant of lesion size and occurrence of steam pops. Baseline LI and LI‐drop are useful surrogate parameters for real‐time assessment of ETC and ΔLI correlates strongly with lesion size. [ABSTRACT FROM AUTHOR]

Background/Objectives: The QDOT‐MICRO™ catheter allows very high‐power and short‐duration (vHPSD) ablation. This study aimed to investigate lesion characteristics using different ablation settings. Methods: Radiofrequency applications (90 W/4 s, temperature‐control mode with 55°C or 60°C target) were performed in excised porcine myocardium using three different approaches: single (SA), double nonrepetitive (DNRA), and double repetitive applications (DRA). Applications were performed with an interval of 1 min for DNRA, and without interval for DRA. Results: A total of 480 lesions were analyzed. Lesion depth and volume were largest for DRA followed by DNRA and SA regardless of catheter direction (depth: 3.8 vs. 3.3 vs. 2.6 mm, p <.001 for all comparisons; volume: 176.6 vs. 145.1 vs. 97.0 mm3, p <.001 for all comparisons). Surface area was significantly larger for DRA than for SA (45.1 vs. 38.3 mm2, p <.001) and larger for DNRA than for SA (44.5 vs. 38.3 mm2, p <.001), but was similar between DRA and DNRA (45.1 vs. 44.5 mm2, p =.54). Steam‐pops more frequently occurred for DRA than for SA (15.6% vs. 4.4%, p =.004) and DNRA (15.6% vs. 6.9%, p =.061), but the incidence was similar between SA and DNRA (4.4% vs. 6.9%, p = 1). Although surface area and lesion volume were larger in lesions with steam‐pops than without steam‐pops (46.5 vs. 38.1 mm2, p =.018 and 128.3 vs. 96.8 mm3, p =.068, respectively), lesions were not deeper (pop(+): 2.5 mm vs. pop(−): 2.6 mm, p =.75). Conclusions: DNRA produces larger lesions than SA without increasing the risk of steam‐pops. DRA produces the largest lesions among the three groups, but with an increased risk of steam‐pops. Even with steam‐pops, lesions do not become deeper in vHPSD ablation. [ABSTRACT FROM AUTHOR]

Introduction: Radiofrequency ablation (RFA) utilizing half‐normal saline (HNS) irrigation is a promising intervention to circumvent commonly encountered limitations during radiofrequency ablation of deep myocardial substrate. Few studies to date have analyzed the morphologic changes in the human myocardium following HNS RFA. Methods and Results: Three patients with symptomatic ventricular tachycardia (VT) who underwent RFA with HNS irrigation underwent pathological specimen examination at time of autopsy or following native heart explant at the time of cardiac transplantation. Gross evaluation of the heart was performed fresh and after fixation in 10% formalin. A routine examination was performed with fixation in 10% formalin. Sections of lesioned tissue were paraffin embedded and evaluated using standard hematoxylin and eosin (H&E) staining. Conclusion: Irrigated RF ablation with HNS irrigant produces coagulative necrosis as well as several delayed histopathological changes with a deeper field of effective ablation. Transmurality may not be obtained in the ventricular myocardium with endocardial, epicardial, or sequential unipolar HNS ablation. [ABSTRACT FROM AUTHOR]

Background Radiofrequency ablation (RFA) is a validated treatment option for the treatment of chronic pain in patients with lumbar spondylosis. Lesion size has been suggested to correlate with good clinical outcomes. This has created an abundance of scientific interest in the development of products with larger lesion characteristics. Needle characteristics, energy transfer, and heat rate are known to modify lesion size. Here, we demonstrate that common intraoperative solutions, such as lidocaine, iodine, and gadolinium-based products, can also affect lesion shape. Objectives To determine whether lidocaine and contrast agents modify lesion characteristics during the performance of monopolar RFA. Study design Controlled, ex vivo study using clinically relevant conditions and pre-injections. Setting Academic institution in a procedural setting. Methods RFA lesion size was compared among six cohorts: 1) lidocaine 1%, 2) lidocaine 2%, 3) iohexol 180, 4) iohexol 240, 5) gadodiamide, and 6) control (no fluid control). Radiofrequency (RF) current was applied for 90 seconds at 80°C via 20-gauge 100-mm standard RFA needles with 10-mm active tips in orgranic chicken breasts without preservative at room temperature (21°C). Twelve lesions were performed for each medication cohort. The length, width, and depth of each lesion were measured. The statistical significance between each medication group and the control group was evaluated by t test. Results The mean lesion surface area of monopolar RFA without any pre-injection used was 80.8 mm2. The mean surface area of the monopolar RF lesion with a pre-injection of 0.2 mL of 2% lidocaine was 114 mm2, and the mean surface area of the monopolar RF lesion with a pre-injection of 0.2 mL of iohexol 240 was 130.6 mm2. The statistical analysis demonstrated that the control group had significantly smaller lesion sizes than did the groups in which lidocaine 2% and iohexol 240 were used (P <0.01). There were no statistically significant differences among the groups in which lidocaine 1%, iohexol 180, and gadodiamide were used. A notable difference was a 20% longer lesion with iohexol 240 compared with the control group and a 20% wider lesion with lidocaine 2% compared with the control group. Limitations In vivo anatomy within a human was not used in this study, nor were the chicken breasts heated to physiological temperature. Randomization of pieces of chicken breast did not occur, and thus intrinsic differences among the chicken breast pieces could play a confounding role. Conclusions Lidocaine 2% and iohexol 240, when used as pre-injections in RFAs, were found to be associated with statistically significant increases in lesion surface area. However, RFAs with lidocaine 1%, iohexol 180, or gadodiamide were not found to produce a statistically significant difference in lesion size compared with monopolar RFA without the use of injectate. [ABSTRACT FROM AUTHOR]

Background: A novel irrigation catheter (QDOT MICRO™) has been introduced, which enables a surface temperature‐controlled ablation combined with tip cooling. However, the detailed description of its complex behavior and effect on the incidence of pops and lesion formation remains elusive. This study aimed to systematically investigate the ablation characteristics, feedback behavior, and incidence of steam pops in a simplified ex vivo swine model. Methods: Using swine ventricular tissue perfused with saline at 37°C, we systematically created lesions with 4×3 combinations of the wattage (20, 30, 40, and 50 W) and contact force (CF, 10, 30, and 50 g). Ablation was continued for either 120 s or until a steam pop occurred and repeated 10 times with each setting. The lesion geometry, ablation index, feedback dynamics, and conditions underlying the steam pops were measured and analyzed. Results: Steam pops occurred particularly frequently in combinations of a low CF and high power (10 g vs. 30 g+50 g [p <.0001]; 40 W+50 W vs. 20 W+30 W [p <.0001]). Failure to activate a feedback process was associated with a 5.1 times higher incidence of steam pops (21/109 vs.11/11, [95% CI 3.499–7.716], p <.0001). The wattage feedback was particularly evident with a high CF (30 and 50 g) and high initial wattage (40 and 50 W). The average delivered wattage at 27 W predicted the occurrence of steam pops. Conclusion: The temperature‐controlled ablation with the QDOT MICRO™ demonstrated a complex feedback behavior, which contributed to a reduced incidence of steam pops and prolonged lead time to the pops. [ABSTRACT FROM AUTHOR]

Background: The local impedance (LI) is an emerging technology that monitors tissue‐catheter coupling during radiofrequency (RF) ablation. The relationships between the LI, RF delivery time, and lesion formation remain unclear. Methods: Using an LI‐enabled RF catheter in an ex vivo experimental model, RF lesions were created combined with various steps in the power (40 and 50 W), CF (10 g, 30 g, and 50 g), and time (10s, 20s, 30s, 40s, 50s, and 60s at 40 W and 5 s, 10s, 20s, 30s, 40s, 50s, and 60s at 50 W). The correlations between the LI drop, lesion size, and RF delivery time were evaluated. The rate of change in the time‐dependent gain in the LI, depth, and diameter and the time to reach 90% decay of the peak dY/dT (time to 90% decay) were assessed. Results: The correlation between the LI drop and ablation time revealed non‐linear changes. The time to a 90% decay in the LI drop differed depending on the RF ablation setting and was always shorter with the 50 W setting than 40 W setting. The LI drop always correlated with the lesion formation under all ablation power settings. Deeper or wider lesions were predominantly created within the time to 90% decay of the LI drop. Conclusion: The LI drop was useful for predicting lesion sizes. Deeper or wider lesions cannot be obtained with a longer ablation than the 90% decay time of the LI drop. A shorter ablation than the 90% decay time of the LI drop would be preferable for an effective ablation. [ABSTRACT FROM AUTHOR]

Background: Steam pops are a rare complication associated with radiofrequency (RF) ablation and are hard to predict. The aim of this study was to assess the influence of coverage between the RF ablation electrode and cardiac tissue on steam pop incidence and lesion size. Methods and results: An ex vivo model using porcine cardiac preparations and contact force sensing catheters was designed to perform RF ablations at different coverage levels between the RF electrode and cardiac tissue. During coverage level I, only the distal part of the ablation electrode was in contact with tissue. During coverage level II half of the ablation electrode, and during coverage level III the entire ablation electrode was embedded in tissue. RF applications (n = 60) at different coverage levels I–III were systematically performed using the same standardized ablation protocol. Ablations during coverage level III resulted in a significantly higher rate of steam pops (100%) when compared to ablations during coverage level II (10%) and coverage level I (0%), log rank p <.001. Coverage level I ablations resulted in significantly smaller lesion depths, diameters, and impedance drops when compared to higher coverage level ablations, p <.001. In the controlled ex vivo model, there was no difference in applied contact force or energy between different coverage levels. Conclusions: The level of coverage between RF electrode, cardiac tissue, and the surrounding fluid significantly influenced the incidence of steam pops in an ex vivo setup. Larger coverage between RF electrode and tissue resulted in significantly larger lesion dimensions. [ABSTRACT FROM AUTHOR]

Background: The critical lesion size treated with bone marrow stimulation (BMS) for osteochondral lesions of the talus (OLTs) has been 150 mm2 in area or 15 mm in diameter. However, recent investigations have failed to detect a significant correlation between the lesion size and clinical outcomes after BMS for OLTs. Purpose: To systematically review clinical studies reporting both the lesion size and clinical outcomes after BMS for OLTs. Study Design: Systematic review. Methods: A systematic search of the MEDLINE and EMBASE databases was performed in March 2015 based on the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Included studies were evaluated with regard to the level of evidence (LOE), quality of evidence (QOE), lesion size, and clinical outcomes. Results: Twenty-five studies with 1868 ankles were included; 88% were either LOE 3 or 4, and 96% did not have good QOE. The mean area was 103.8 ± 10.2 mm2 in 20 studies, and the mean diameter was 10.0 ± 3.2 mm in 5 studies. The mean American Orthopaedic Foot and Ankle Society score improved from 62.4 ± 7.9 preoperatively to 83.9 ± 9.2 at a mean 54.1-month follow-up in 14 studies reporting both preoperative and postoperative scores with a mean follow-up of more than 2 years. A significant correlation was found in 3 studies, with a mean lesion area of 107.4 ± 10.4 mm2, while none was reported in 8 studies, with a mean lesion area of 85.3 ± 9.2 mm2. The lesion diameter significantly correlated with clinical outcomes in 2 studies (mean diameter, 10.2 ± 3.2 mm), whereas none was found in 2 studies (mean diameter, 8.8 ± 0.0 mm). However, the reported lesion size measurement method and evaluation method of clinical outcomes widely varied among the studies. Conclusion: An assessment of the currently available data does suggest that BMS may best be reserved for OLT sizes less than 107.4 mm2 in area and/or 10.2 mm in diameter. Future development in legitimate prognostic size guidelines based on high-quality evidence that correlate with outcomes will surely provide patients with the best potential for successful long-term outcomes. [ABSTRACT FROM AUTHOR]

In Vitro Comparison of Open-Irrigated Catheters Introduction Open-irrigated radiofrequency ablation catheters with slight differences in tip architecture are widely used, although limited comparative data are available. The purpose of this study was to compare the lesion size and potential complications produced by commercially available open-irrigated catheters in an in vitro porcine heart model. Methods and Results Six catheters were tested (Biosense Webster Thermocool, Boston Scientific Open irrigated, St. Jude CoolPath, St. Jude CoolPath Duo, Biosense Webster Thermocool SF, St. Jude Cool Flex) at 20 and 35 W power-control, under 2 different blood flows (0.1 and 0.5 m/s) and at 2 target durations (30 and 60 seconds). A total of 601 lesions were made in 26 in vitro preparations. The tip temperature profile showed significant differences between the catheters (P < 0.001) with the Thermocool SF registering the lowest. Only the surface diameter and the depth at maximum diameter of the lesion were influenced by the design of the ablation electrode. The lesion volume did not show significant differences between catheters for any power, application duration or blood flow condition. Char and pops occurred more often at 35 W with only slight differences between the catheters. Conclusions Tip design of the 6 different irrigated catheters does not affect the lesion total volume, although a slight difference in lesion geometry in terms of surface diameter and depth at maximum diameter is present. The catheters show a slight different in vitro safety profile [ABSTRACT FROM AUTHOR]