The eradication of ventricular tachycardia (VT) isthmus sites constitutes the minimal procedural endpoint for VT ablation procedures. Contemporary high-resolution computed tomography (CT) imaging, in ...combination with computer-assisted analysis and segmentation of CT data, facilitates targeted elimination of VT isthmi. In this context, inHEART offers digitally rendered three-dimensional (3D) cardiac models which allow preoperative planning for VT ablations in ischemic and non-ischemic cardiomyopathies. To date, almost no data have been collected to compare the outcomes of VT ablations utilizing inHEART with those of traditional ablation approaches.
The presented data are derived from a retrospective analysis of n = 108 patients, with one cohort undergoing VT ablation aided by late-enhancement CT and subsequent analysis and segmentation by inHEART, while the other cohort received ablation through conventional methods like substrate mapping and activation mapping. The ablations were executed utilizing a 3D mapping system (Carto3), with the mapping generated via the CARTO® PENTARAY™ NAV catheter and subsequently merged with the inHEART model, if available.
Results showed more successful outcome of ablations for the inHEART group with lower VT recurrence (27% vs. 42%, p < 0.06). Subsequent analyses revealed that patients with ischemic cardiomyopathies appeared to derive a significant benefit from inHEART-assisted VT ablation procedures, with a higher rate of successful ablation (p = 0.05).
Our findings indicate that inHEART-guided ablation is associated with reduced VT recurrence compared to conventional procedures. This suggests that employing advanced imaging and computational modeling in VT ablation may be valuable for VT recurrences.
Background
High-power short-duration (HPSD) radiofrequency ablation (RFA) is highly efficient and safe while reducing procedure and RF time in pulmonary vein isolation (PVI). The QDot™ catheter is a ...novel contact force ablation catheter that allows automated flow and power adjustments depending on the local tissue temperature to maintain a target temperature during 90 W/4 s lesions. We analysed intraprocedural data and periprocedural safety using the QDot-catheter in patients undergoing PVI for paroxysmal atrial fibrillation (PAF).
Methods
We included
n
= 48 patients undergoing PVI with the QDot-catheter with a temperature-controlled HPSD ablation mode with 90 W/4 s (TC-HPSD). If focal reconnection occurred besides repeat ablation, the ablation mode was changed to 50 W/15 s (QMode).
N
= 23 patients underwent cerebral MRI to detect silent cerebral lesions.
Results
Mean RF time was 8.1 ± 2.8 min, and procedure duration was 84.5 ± 30 min. The overall maximal measured catheter tip temperature was 52.0 °C ± 4.6 °C, mean overall applied current was 871 mA ± 44 mA and overall applied energy was 316 J ± 47 J. The mean local impedance drop was 12.1 ± 2.4 Ohms. During adenosine challenge,
n
= 14 (29%) patients showed dormant conduction. A total of
n
= 24 steam pops were detected in
n
= 18 patients (39.1%), while no pericardial tamponade occurred. No periprocedural thromboembolic complications occurred, while
n
= 4 patients (17.4%) showed silent cerebral lesion.
Conclusions
TC-HPSD ablation with 90 W/4 s using the QDot-catheter led to a reduction of procedure and RF time, while no major complications occurred. Despite optimized temperature control and power adjustment, steam pops occurred in a rather high number of patients, while none of them leads to tamponade or to clinical or neurological deficits.
Abstract
Background
Left ventricular lead (LVL) implantation can be challenging in Cardiac Resynchronization Therapy (CRT). Therefore, contrast is commonly used to visualize the coronary venous ...system. However, contrast use is correlated with substantial risks such as contrast-induced nephropathy and anaphylactic reaction. Case studies suggest feasibility of LVL implantation without coronary sinus (CS) venography.
Purpose
We aimed to compare the procedure characteristics, outcome, and safety of contrast-free and contrast-aided LVL implantation.
Methods
346 LVL implantations performed between 2017 and 2019 were analyzed. 167 were contrast free (No-Contrast Group: NCG), and 179 were contrast-aided (Contrast Group: CG). The intervention duration, fluoroscopy duration, and radiation dose were evaluated. The primary outcome was procedural success. The secondary outcomes were LVL position, LVL threshold value, QRS duration and LVEF. Operative complications and lead revisions were surrogates for the intervention’s safety.
Results
The LVL implantation success rate varied from 62.9% in the NCG to 96.6% in the CG (Figure 1). Contrast-free interventions were associated with shorter procedure and fluoroscopy durations, and smaller radiation doses (100.8±41.0 vs 131.1±50.0min (p<0.01), 15.7±11.2 vs 26.0±17.5min (p<0.01) and 475.3±422.7 vs 897.3±779.1Gy.cm2 (p<0.01) respectively). The intraoperative LVL threshold values were equivalent (0.96±0.65 in the NCG vs 1.05±0.65V in the CG, TOST-p<0.01), and contrast use did not significantly influence the follow-up LVL threshold, QRS shortening and LVEF increase (1.11±0.55 vs 1.22±0.93V (p=0.62), -10.5±28.3 vs -13.2±26.3ms (p=0.16) and 2.3±8% vs 4.1±8.4% (p=0.40)). More intraoperative complications (CS dissection, perforation, mechanically-induced arrhythmia and other respiratory or circulatory problems) were observed during the contrast-aided procedures (9.5% in the CG versus 1.9% in the NCG, p=0.04). However, the postoperative complication rates (ICU admission, pericardial effusion, pneumothorax, infection and LVL revision) did not differ (9.5% in the NCG, 12.8% in the CG, p=0.55). In contrast-free LVL implantation failure cases, intraoperatively crossing over from the NCG to CG did not result in longer procedures or different intraprocedural complication rates (131.8±46.8 vs 131.1±50.0min in the CG (p=0.9) and 6.5% vs 9.5%, (p=0.6)).
Conclusion
Contrast-free LVL implantation was associated with shorter intervention and fluoroscopy durations and less radiation. Less intraoperative complications were observed without contrast, and the postoperative complication rate was similar to contrast-aided procedures. This technique was successful in almost 2/3 of the cases. In case of failure and crossover to contrast, the initial contrast free attempt did not result in more adverse events than in fully contrast-aided procedures. It is therefore reasonable to consider an initial contrast-free approach for CRT implantation.Compared groups
Alloy 430 stainless steel tube-to-header welds failed in a heat recovery steam generator (HRSG) within one year of commissioning. The HRSG was in a combined cycle, gas-fired, combustion turbine ...electric power plant. Alloy 430, a 17% chromium (Cr) ferritic stainless steel, was selected because of its resistance to chloride and sulfuric acid dewpoint corrosion under conditions potentially present in the HRSG low-pressure feedwater economizer. Intergranular corrosion and cracking were found in the weld metal and heat-affected zones (HAZs). The hardness in these regions was up to 35 HRC, and the weld had received a postweld heat treatment (PWHT). Metallographic examination revealed that the corroded areas contained undertempered martensite. Fully tempered weld areas with a hardness of 93 HRB were not attacked. No evidence of corrosion fatigue was found. Uneven temperature control during PWHT was the most likely cause of failure.
Since 2004, clinical trials of medicinal products have to be approved by the federal authorities in Germany. Authorization is necessary in addition to the favorable opinion of the concerned ethics ...committee. This procedure has undoubtedly resulted in larger expenditures with respect to time and costs of planning and conducting of clinical trials. However, the implementation of Good Clinical Practice has also increased both safety for the trial subjects and validity of the data. The most important laws and regulations, definitions, the procedures for submitting a clinical trial application as well as subsequent amendments are described and further information is provided.
Abstract
Funding Acknowledgements
Type of funding sources: None.
Introduction
In persistent AF, outcomes after PVI alone is worse as the pathophysiology remains unclear. Prolonged AF duration is an ...independent predictor for worse success rates after catheter ablation. In this study, we investigated efficacy and safety of ablation of spatio-temporal dispersions, as additional ablation strategy after PVI in patients with long-standing persistent AF.
Methods
All consecutive patients with long-standing persistent AF treated with an AI-based algorithm for detection of spatio-temporal dispersion in our institution between 05/21 and 10/22 were included (n = 41, see table 1). The procedure was done using a high-density 3D-Map and an algorithm for detection of right and left atrial areas with spatio-temporal dispersion (DISPERS). Ablation of DISPERS was aiming at homogenizing, dissecting, isolating or connecting DISPERS areas to non-conducting structures. Follow-up contained regular visits at our out-patient-clinic and repetitive 7 day Holter ECGs. Late recurrence (LR) was defined as recurrence after 90 days or as recurrence, which caused further ablation. All complications requiring intervention or causing long-term sequelae were classified as major complications.
Results
In 24/41 pts (58.5%), the DISPERS guided ablation was the first AF ablation. Patients were suffering from very long-standing persistent AF with a mean AF duration of 64.89 ± 54.77 months. Additional to circumferential PVI, ablation of all detected left atrial (100%) and right atrial (68.3%) DISPERS areas was performed, leading to significant slowing of AF cycle length (mean 23.3%) or termination of AF to AT (5/41, 12.2%) or direct conversion to SR (6/41, 14.6%).
One major complication occurred (1/41 (2.4%), pseudoaneurysm, resolving after manual compression). Three patients (7.3%) required temporary external pacing due to delayed sinus recovery after the procedure. No patient was in need of permanent pacemaker implantation.
LR occurred in 25 patients (61.0 %): In 8/25 patients (32 %), LR was solely AF, whereas in 15/25 patients (60%) LR was a left AFlutt. In 2 patients (8%), AF and left AFlutt was detected.
During a follow-up of 231 ± 129 days, 72.9 % of patients remained in sinus rhythm undergoing 1.6 ± 0.68 ablations (s. Figure 1; 4,9% of patients on AAD). Additionally, Figure 2 illustrates the AF-free outcome in all patients.
Conclusion
Ablation of arrhythmogenic substrate identified by spatio-temporal dispersion yielded in this cohort of extensively long-standing persistent AF patients in high success rates regarding elimination of AF. Most arrhythmia recurrences were reentrant AT. After a total of 1.6 procedures, freedom from AF and AT was >72%. Despite prolonged procedure times, complication rates remained very low. Extending study population and follow-up is needed to evaluate long-term efficacy of dispersion-guided ablation.
Abstract
Funding Acknowledgements
Type of funding sources: None.
Background
Radiofrequency ablation remains one of the most important ablation techniques in the EP lab. Creating durable lesion is ...difficult, as progression of lesion formation cannot be observed directly. Surrogate parameters, as force-time-integral and indices, as the ablation index or lesion size index, help distinguishing the efficacy of a RF-application, but several deficiencies are known. The aim of this study was to further investigate dynamic changes in ablation parameters and lesion growth in RF-ablation.
Methods
RF-lesions were created using an ex vivo porcine cardiac model with a force and local impedance sensing catheter. A second catheter was used for lesions up to 70 Watts. The experimental setup consisted of a saline-filled container, a dispersive electrode, a heated thermostat and a circulation pump to imitate in vivo conditions. Global impedance was kept at 120 Ohm as well as the temperature at 37°C. RF-lesions were created using identic values of RF duration and electrode tissue coupling. RF power of 20W, 30W, 40W, and 50W was used in the local impedance sensing catheter, while RF power of 30W, 40W, 50W, 60W, and 70W were used in the second catheter.
All parameters (power, temperature, global impedance, ETC, lesion diameter and lesion depth) were measured once per second during application of RF-current, enabling real-time correlation of RF parameters and lesion size. In case of an audible steam pop, RF application was stopped.
Results
In total, 61 lesions were included in the analysis. Due to at least 60 measurements per lesion, 3321 data points with all ablation parameters (power, temperature, global impedance, lesion diameter and lesion depth) were collected and analyzed.
Throughout the application, lesion progression was highest in the first seconds of RF application and showed a slowing approximation to a maximum (Figure 1 and 2). Potential maximum lesion size seems to be defined by selected power level (s. Figure 3). Interestingly, these findings were seen in all power levels from 20 – 70 W (s. Figure 3).
75 % of final lesion size was achieved after 12-25 seconds, depending on selected power levels (s. Figure 4). In high power ablation (> 50 W), 75% of final lesion size was reached significantly earlier compared to lower power levels (20-40 W, s. Figure 4).
Conclusion
In RF-ablation, lesion growth is not linear. A slowing approximation of lesion diameter and depth to a maximum is observed. This finding should be considered in clinical settings to avoid steam pops and collateral damage due to a long RF duration despite little changes in lesion size. Further investigation is needed for a surrogate parameter, which is able to assess declining lesion growth after the first seconds of RF-application.
Abstract
Funding Acknowledgements
Type of funding sources: None.
Background
Radiofrequency current remains one of the most important ablation techniques in the EP lab. Creating durable lesions is key ...to successful ablation. Evaluating lesion quality and progression of lesion growth is difficult as many parameters influence lesion formation. Therefore, several approaches were developed, as monitoring RF duration, power and contact force seems insufficient in clinical practice. Force-time-integral (FTI) and force-time-current-integral (FTCI), as well as the ablation index (AI) and lesion size index (LSI) showed decent results in past studies. Recently, a new force sensing catheter (NFSC) was released. By now, data about lesion formation and correlation with the FTI, FTCI and LSI is lacking with this NFSC. This study aimed to further investigate lesion formation with the NFSC in an ex vivo model.
Methods
30 RF-lesions were created using an ex vivo porcine cardiac model with the NFSC catheter. The experimental setup consisted of a saline-filled container, a dispersive electrode, a heated thermostat and a circulation pump to imitate in vivo conditions. Global impedance was kept at 120 Ohm as well as the temperature at 37°C. In a first set of lesions, CF was varied (1g, 5g, 10g, 20g). Three lesions were created in each CF-level with 30W. In a second set of lesion, CF was kept at 10 – 15 g, but ablation power was set to 20W, 30W, 40W, 50W, 60W and 70W. In every power level, three lesions were created.
All parameters (power, temperature, global impedance, contact force, lesion size) were measured constantly during application of RF-current, enabling real-time correlation of RF parameters and lesion size. In case of an audible steam pop, RF application was stopped.
Results
1640 measurement in 30 lesions were included into the analysis. Mean lesion diameter was 7.82 ± 1.52 mm, mean lesion depth 4.80 ± 1.08 mm. Baseline global impedance (GI) was 138.10 ± 10.93 Ω, mean GI-drop 28.10 ± 8.00 Ω. In average, CF of 12.10 ± 5.87 g was used.
Correlations of lesion size, FTI and FTCI are shown in table 1. Interestingly, LSI correlated best with lesion size (r = 0.851 and r = 0.852 for lesion depth and diameter; p<0.001). Figure 1 illustrates a scatter plot of LSI and lesion depth (Figure 1a) and lesion diameter (Figure 1b).
Figure 2 shows dynamic changes in lesion depth compared to changes in LSI and FTCI. During RF-application, development of lesion formation and LSI is comparable from approximately second 7 onwards. FTCI is rising in a linear manner, whereas lesion formation increases monoexponentially.
Conclusion
In the NFSC, lesion size correlates strongest with the LSI in power levels up to 70 Watts. FTI and FTCI also showed decent correlations. Regarding dynamic changes in lesion size, LSI is best comparable to actual lesion growth.
Abstract
Funding Acknowledgements
Type of funding sources: None.
Background
Several parameters are assumed to influence lesion size in RF ablation. Especially RF power, duration and contact force are ...considered for optimizing lesion quality and creating durable lesions. Recent data showed a significant influence of electrode-tissue-coupling (ETC) on lesion size and occurrence of steam pops. Therefore, this study aimed to investigate the impact of ETC and contact force on lesion progression in RF ablation.
Methods
RF-lesions were created using a contact force sensing catheter with the ability of measuring local impredance in an ex vivo porcine cardiac model. The experimental setup consisted of a saline-filled container, a dispersive electrode, a heated thermostat and a circulation pump to imitate in vivo conditions. Global impedance was kept at 120 Ohm as well as the temperature at 37°C. RF power of 20W, 30W, 40W, and 50W was used. The ETC levels (full/minor) and CF-level (1-5g, 10-15g and 20-25g) were systematically varied between minor and full coupling. In minor ETC-level, only the distal end of the catheter is in contact with the tissue. In full ETC-level, the whole catheter tip is in contact with the tissue. All parameters (power, temperature, global and local impedance, contact force, ETC, lesion size) were measured constantly during application of RF-current, enabling real-time correlation of RF parameters and lesion size. In case of an audible steam pop, RF application was stopped.
Results
8654 measurements out of 72 lesions were included in analysis. Significant differences in lesion size were observed when ETC-level was differed. Lesion depth was significantly higher in full ETC-level (5.13 ± 0.99 mm vs. 9.45 ± 1.45 mm, p<0.001). No significant difference was seen in lesion diameter and depth by varying CF-level, when lesions were created in full ETC-level (Table 1). These findings are also illustrated in Figure 1.
When lesions were analyzed in minor ETC-level only, significant differences were observed, when CF-levels were varied (Table 2).
Conclusion
ETC is a main predictor of lesion size in RF-ablation. CF also influences lesion depth and diameter. However, significant differences were only observed in minor ETC-levels. Consequently, CF might be a main factor for durable lesions in RF-ablation, but the influence of varied CF decreases when ETC-level is rising.
Abstract
Funding Acknowledgements
Type of funding sources: None.
Background
Radiofrequency (RF) current remains the most ablation technology in the electrophysiologic laboratory. Durable lesion ...formation without collateral tissue damage is key for obtaining efficient and safe procedures. RF power, duration and contact force are considered as main determinants of lesion size. Recently published data show that electrode tissue coupling (ETC) is another important parameter of lesion formation. This ex vivo model was created to investigate local impedance changes and lesion size when alternating ETC-levels.
Methods
RF-lesions were created using a force and local impedance sensing catheter in an ex vivo porcine cardiac model. The experimental setup consisted of a saline-filled container, a dispersive electrode, a heated thermostat and a circulation pump to imitate in vivo conditions. Global impedance was kept at 120 Ohm as well as the temperature at 37°C. RF-lesions were created using identic values of RF duration and contact force. A RF power of 20W, 30W, 40W, and 50W was used. The ETC levels were systematically varied between minor and full coupling. In minor ETC-level, only the distal end of the catheter is in contact with the tissue. In full ETC-level, the whole catheter tip is in contact with the tissue. All parameters (power, temperature, global and local impedance, contact force, ETC, lesion size) were measured constantly during application of RF-current, enabling real-time correlation of RF parameters and lesion size. In case of an audible steam pop, RF application was stopped.
Results
8654 measurements of lesion depth and diameter were analyzed after creating 72 lesions. Lesion depth and diameter in full ETC-level were significantly higher compared to minor ETC-level (s. Table 1). Interestingly, lesions in lower power levels (20-30 Watt), but full ETC-level became wider and deeper than lesions in high power levels (40-50 Watts), but minor ETC-level (s. Figure 1).
These observations were made despite shorter RF-duration (54.00 ± 13.07 s vs. 47.11 ± 17.57 s, p=0.032) in lesions with full ETC-level due to higher incidence of steam pops (14 vs. 6 steam pops, p = 0.032).
Baseline LI and LI-drop were significantly higher in full ETC-level (Figure 2), but no relevant difference was observed in baseline GI.
Conclusion
Baseline LI and LI changes during ablation provide information about ETC-levels and interaction of the RF ablation catheter with cardiac tissue. ETC-levels, as predicted by LI, had a significantly higher impact on RF lesion size than RF power or RF-duration. Therefore, LI should be monitored during RF ablation for estimating ETC-levels and lesion formation.
