Esophageal Temperature Research Articles

Validity of a wearable core temperature estimation system in heat using patch-type sensors on the chest

This study aimed to evaluate the reliability of a patch-type sensor on the upper chest region that uses a dual-heat-flux method to estimate core temperature under various heat conditions. The participants’ esophageal and rectal temperatures (Teso and Trec) were measured with real-time monitoring of predicted core temperature (Tpre) using the patch. Twenty-one volunteers wearing work clothes and nine volunteers wearing protective clothing walked (5.0 km/h) for an hour at 35 °C. During exercise, Teso increased to 37.9 ± 0.3 °C and 38.2 ± 0.2 °C for each group, respectively. The root mean squared errors (RMSEs) were 0.18 ± 0.05 °C and 0.25 ± 0.08 °C between Teso and Tpre and were 0.31 ± 0.10 °C and 0.34 ± 0.11 °C between Trec and Tpre in each clothing condition, respectively. In addition, 11 volunteers walked for an hour at 30 °C or 40 °C. The Teso during exercise increased to 37.7 ± 0.3 °C and 38.2 ± 0.3 °C, respectively. The RMSEs were 0.23 ± 0.10 °C and 0.18 ± 0.05 °C between Teso and Tpre in each ambient temperature condition, respectively. Furthermore, eight volunteers performed an arm-cranking exercise (60 W) for 30 min at 35 °C. The Teso increased to 37.9 ± 0.2 °C during exercise. The RMSEs were 0.22 ± 0.07 °C between Teso and Tpre. The proportions of all paired measurements differing by less than the predefined threshold for validity of ≤ 0.3 °C were 85 ± 18% between Teso and Tpre. These data indicate that the patch is capable of providing a moderate estimate of core temperature during low-intensity and acute exercise under heat conditions.

Esophageal image segmentation for guidance of posterior wall lesions during atrial fibrillation ablation.

Despite luminal esophageal temperature (LET) monitoring, esophageal injury remains a risk which impacts decision making during atrial fibrillation (AF) ablation. We sought to compare procedural characteristics including radiofrequency (RF) power, duration, and LET, among ablation procedures with and without image segmentation for esophageal visualization (EV). The retrospective cohort included 73 patients (mean age 65.2 ± 8.6years, 36% female, 55% paroxysmal AF) who underwent pre-procedural cardiac magnetic resonance or computed tomography and LET monitoring. Of all patients, 35 were historical patients that underwent standard AF ablation without EV, and 38 were contemporary patients, 28 of whom underwent AF ablation with EV and 10 that underwent AF ablation without EV. Total RF time was similar between the groups. The distribution of ablation power delivery was skewed toward higher power in the contemporary patients. However, among patients in the contemporary group, the proportion of > 35 Watts lesions was lower with EV (P < 0.001). There was no difference between the max or mean LET. The standard deviation of LET change within patient during posterior wall ablation was lower in those with esophageal visualization compared to historical controls, but no change was seen compared to a smaller group of contemporary controls. No long-term clinical esophageal injury was observed. In a retrospective analysis, EV was successfully performed in 28 patients. EV impacted RF power delivery decisions but was unassociated with RF time, changes in LET, or long-term safety.

Temperature measurements of a wearable and wireless axillary sensor iThermonitor but not a bladder probe represents the core temperature during laparoscopic rectal surgery.

To investigate whether the temperature recorded by an iThermonitor has better concordance with the core temperature than the bladder temperature recorded by a Foley catheter sensor in laparoscopic rectal surgery. Eighty-two adults undergoing laparoscopic rectal surgery were enrolled. Temperatures were continuously measured by a distal oesophageal probe (the reference core temperature), axillary iThermonitor and Foley catheter sensor (bladder temperature) in each patient during surgery. Pairs of axillary and core temperatures or pairs of bladder temperature and core temperatures were compared and summarized using linear regression and the repeated-measured Bland-Altman method during the whole surgical period and pneumoperitoneum period. There were 3303 pairs of temperature measurements during the whole surgical period. The mean difference between iThermonitor and oesophageal was 0.05°C ; the limits of agreement were - 0.48 to 0.56°C. The mean difference between the oesophagus and bladder was 0.28°C; the limits of agreement were - 0.39 to 0.94°C (P < 0.001, F-test vs. iThermonitor). Ninety -five% of all iThermonitor values were within 0.5°C of oesophageal temperature, whereas the proportion for oesophageal and bladder differences within 0.5°C was only 84% (95% confidence interval 80-88%). Lin's CCC for the iThermonitor and bladder measurements were 0.842 (95%CI: 0.831-0.851) and 0.688 (95%CI: 0.673-0.703) respectively. Similar results were found during the pneumoperitoneum period. The temperature recorded by iThermonitor has better concordance with the core temperature than the bladder temperature recorded by Foley catheter sensor in laparoscopic rectal surgery.

Sevoflurane Sparing Effect of Morphine in Tegus (Salvator merianae) – A Preliminary Study

This study aimed to determine the minimum anesthetic concentration (MAC) of sevoflurane in tegus (Salvator merianae) and the morphine-sparing effect on this variable. In a prospective, non-blinded, crossover study, MAC was first determined in 6 tegus under sevoflurane anesthesia alone (MACSEVO) and then following intramuscular administration of morphine (10 mg/kg), administered 3 hour before sevoflurane anesthesia (MACSEVO+MOR). A standard bracketing technique was applied to determine the MAC by an electrical supramaximal noxious stimulus (50 Hz, 30 mA) delivered at the base of the tail of the tegus. The end-tidal sevoflurane fraction was reduced or increased by 10% in any evidence of negative or positive motor responses, respectively. The MAC was calculated as the mean of the 2 highest successive sevoflurane concentrations that permitted positive responses and the 2 lowest that prevented positive responses. Heart rate, esophageal temperature, and noninvasive mean arterial blood pressure were assessed every 10 minutes. The MAC was significantly different between MACSEVO (2.41 ± 0.06%) and MACSEVO+MORF (1.88 ± 0.43%) (P = .007), with a mean ± SD morphine-induced reduction in the sevoflurane MAC of 22 ± 18% (P = .0158). Heart rate, mean arterial blood pressure, and esophageal temperature did not differ between groups or within groups over time. Results showed that intramuscular premedication with 10 mg/kg morphine produced a sevoflurane sparing effect in tegus with no significant impact on cardiovascular variables.

5S Study: Safe and Simple Single Shot Pulmonary Vein Isolation With Pulsed Field Ablation Using Sedation.

Pulsed field ablation represents an energy source specific for ablation of cardiac arrhythmias including atrial fibrillation. The aim of the study was to describe the adoption and the process of streamlining procedures with a new ablation technology. All-comer atrial fibrillation patients (n=191; mean age 69±12 years) underwent catheter ablation with a pulsed field ablation ablation device exclusively using analog-sedation. In the validation phase (n=25), device electrogram quality was compared with a circular mapping catheter to assess pulmonary vein isolation and esophageal temperature monitoring was used. In the streamline phase (n=166), a single-catheter approach was implemented. Postprocedural cerebral magnetic resonance imaging was performed in 53 patients. In 52 patients, esophageal endoscopy was performed at day 1 after the procedure. Follow-up was performed using 72 hours Holter ECGs. On a pulmonary vein basis, pulmonary vein isolation rate was 100% including a single shot isolation rate of 99.5%. The electrogram information of the pulsed field ablation catheter and the circular mapping catheter were 100% congruent. Neither esophageal temperature rises nor esophageal thermal injury were observed. Two minor strokes occurred, presumable due to air embolism during catheter exchanges through the large bore sheath (13.8 F ID). In the streamline phase, reduced procedure times (46±14 versus 38±13 minutes, P=0.004), no further strokes and a low incidence of silent cerebral injury (10/53 patients; 19%) were noted. During short-term follow-up, 17/191 patients (9%) had a atrial tachyarrhythmia recurrence. The pulsed field ablation device allows for simple and safe simple single shot pulmonary vein isolation using standard sedation protocols. Procedural speed and efficacy are remarkable and streamlining measures have added safety.

Relationship between the posterior Atrial Wall and the ESOphagus: esophageal position and temperature MEasurement during Atrial Fibrillation ablation. (AWESOME-AF)

Abstract Funding Acknowledgements Type of funding sources: None. Background Pulmonary Vein Isolation (PVI) implies unavoidable ablation lesions on the left atrial posterior wall (LAPW), which is closely related to the esophagus, resulting in several complications. Objective To evaluate the usefulness of the esophageal isodistance print in avoiding temperature rises caused by radiofrequency (RF) application at the LAPW during paroxysmal AF ablation. Methods An isodistance map of the atrio-esophageal relationship (esophageal fingerprint) was derived from the preprocedural multidetector computerized tomography MDCT. Patients where randomized on a 1:1 basis in two groups. The PRINT group had a modified PVI line based on the esophageal fingerprint. The CONTROL group underwent standard PVI, and the operator was blinded to the fingerprint (Figure A). Primary endpoint was temperature rise detected by the intraluminal esophageal temperature monitoring probe. The esophageal probe position was verified with the fluoroscopy. Ablation settings were as specified on the Ablate BY-LAW protocol. Results 60 consecutive patients [42 (70%) men, mean age 60±11 years] referred for paroxysmal AF ablation were randomized. As shown in figure B, a temperature rise (&amp;gt;39,1ºC) occurred in 5 (16%) patients on the PRINT group Vs. 17 (56%) on the CONTROL group (p&amp;lt;0,01). Conclusion The esophageal fingerprint allows for a reliable identification of the esophageal position and its use is superior to standard approach in avoiding esophageal temperature rises. The development of new imaging-derived tools can improve patient safety. Long term follow-up is needed to evaluate for impact of PVI line modification on outcomes in terms of AF recurrence.

Impact of very wide antral pulmonary vein isolation on esophageal temperature changes during pulsed field ablation

Abstract Funding Acknowledgements Type of funding sources: None. Background Esophageal thermal injury (ETI) is a serious drawback of available energy sources for atrial fibrillation (AF) ablation, especially on the posterior left atrial (LA) wall. Pulsed field ablation (PFA) is a novel non-thermal energy source with promising safety advantages over existing methods due to its unique myocardial tissue specificity sparing the esophagus. Objective To evaluate esophageal temperature changes during very wide antral pulmonary vein isolation (PVI) using the PFA system. Methods Thirteen consecutive AF patients (62% with paroxysmal AF; age: 61 years; 70% male) underwent first-time PFA under deep sedation. Eight pulse trains (2kV/2.5 sec, bipolar, biphasic, 4x basket/flower configuration each) were delivered to each pulmonary vein (PV). Extra pulse trains in the flower configuration were added for very wide antral circumferential ablation (vWACA). Continuous intraluminal esophageal temperature (TESO) was monitored with an S-shaped esophageal temperature probe. Results A median of 32 (IQR 32;32) and 8 (IQR 8;9) pulse trains for PVI and vWACA with a procedural time and catheter dwell time of 67 min (IQR 61-69) and 17 min (IQR 16-18) were applied. PFA with vWACA resulted in consecutive posterior LA wall isolation in 11/13 patients. Fluoroscopically, the esophagus coursed near the right PVs in 2/13, left PVs in 8/13 and mid-posterior wall position in 3/13 patients. Maximum TESO increase from baseline was 0.8 ±0.9 °C. However, no clinically relevant TESO changes occurred (Table 1). On short-term, all patients remained asymptomatic for sore throat, cough, or other symptoms potentially related to ETI. No esophago-duodenoscopy was necessary. Conclusion PFA of the PVs and lesion extension to the posterior LA wall demonstrated clinically non-significant TESO changes and has the potential to eliminate the risk of a thermal damage to the esophagus.

Early results of the novel radiofrequency balloon ablation catheter for pulmonary vein isolation

Abstract Funding Acknowledgements Type of funding sources: None. Background Pulmonary vein isolation (PVI) remains the cornerstone for treating of symptomatic atrial fibrillation (AF). Single-shot PVI technologies have evolved as a standard for first-time PVI. A novel radiofrequency balloon ablation catheter is now available to offer single-shot RF pulmonary vein isolation. Purpose To summarize the early experience using the novel RF balloon ablation catheter for patients undergoing PVI in two tertiary centres in Europe. Methods We prospectively assessed the first 38 consecutive patients undergoing PVI using RF balloon ablation catheter for paroxysmal or persistent AF in two high volume centres. Both centres used a standardised approach including ultrasound-guided vascular access, uninterrupted anticoagulation, transeptal puncture via the RF balloon sheath and a limited 3D mapping software-guided LA geometry created with a circular mapping catheter. Radiofrequency application for 60s to the anterior segments and 20s posteriorly was performed in all cases, phrenic pacing was employed for ablation of right PVs. BHS performed all procedures (except 2 cases due to high BMI and severe sleep apnea) under sedation, while all patients from UHZ underwent PVI procedures with general anaesthesia as per institutional protocol. All patients had an oesophageal temperature probe to assess oesophageal temperature during ablation (passed orally under sedation) and had uninterrupted oral anticoagulation throughout the periprocedural period. Results Overall, mean age was 64±8 years, 23 (61%) were male, 24 (63%) of patients had paroxysmal AF. The majority were de novo interventions (92%). There was no significant difference between the patients demographics in the two hospitals. All veins were isolated in both groups with a total of 144 applications (n = 73 in the sedation group, n = 71 in the GA population). Median fluoroscopy time was comparable (sedation group 1.1 minutes vs GA group 1.2 minutes; P = 0.58), but median procedure time was shorter in the sedation group (65 minute vs 106 minutes; P &amp;lt; 0.001). The median number of RF ablation per patient (sedation group 7 vs GA group 9; P = 0.32) and time to isolation of each vein (sedation group 11 seconds vs GA group 10 seconds; P = 0.9) were similar. Number of acute reconnections requiring further ablations were not significantly different between groups (sedation group 11 [15%] vs GA group 14 [20%]; P = 0.96). One patient sustained transient phrenic nerve injury in the sedation group. Conclusion Our early experience shows the novel HS balloon ablation can be performed effectively, efficiently and safely under either GA or conscious sedition. The RF balloon ablation catheter paradigm lends itself to refined workflows, with low fluoroscopy requirements and a short learning curve even in initial cohorts.

Comparison of ostial versus very wide antral circumferential pulmonary vein isolation using pulsed field ablation

Abstract Funding Acknowledgements Type of funding sources: None. Background Pulmonary vein isolation (PVI) is the gold standard for first-time atrial fibrillation (AF) ablation procedures. Wide antral circumferential ablation (WACA) in comparison to ostial PVI has been attributed to an improved rhythm outcome after AF ablation. Pulsed field ablation (PFA) is a novel energy source with promising safety and efficacy advantages over existing ablation methods due to its unique myocardial tissue specificity. Feasibility of PFA for very WACA has not been investigated so far. Objective To evaluate procedural characteristics and lesion formation during wide antral circumferential PVI in comparison to ostial PVI using a PFA system. Methods Thirty-seven consecutive AF patients underwent first-time PFA under deep sedation. Patients eighter received ostial (ostial group; N = 15: 66 % paroxysmal AF; age: 69 years; 66 % male) or very wide antral (vWACA group; N = 22: 59 % paroxysmal AF; age: 62 years; 73 % male) PFA. Pre and post ablation LA voltage maps were acquired using a 20-pole spiral catheter together with a 3-dimensional electroanatomic mapping system (voltage cutoff ≤0.5 mV). On post ablation maps, lesion size by encircling the ablated area was measured. In all patients, 8 pulse trains (2kV/2.5 sec, bipolar, biphasic, 4x basket/flower configuration each) were delivered to each pulmonary vein (PV). In the vWACA-group, extra pulse trains in flower configuration were added to each PV in a wide antral position continuous intraluminal esophageal temperatures (TESO) were monitored with an S-shaped esophageal temperature probe. Results A median of 8 [IQR 8;8] and 10 [IQR 10;11] pulse trains per PV for ostial and vWACA PVI were applied. vWACA PFA resulted in significant larger lesion formation (47.3 cm2 [IQR 39.1; 52.0]) in comparison to ostial PFA (35.5 cm2 [IQR 30.3; 38.1], p=0.013) with consecutive posterior LA wall isolation in 19/22 (86 %) patients (Figure 1). In the vWACA group, median TESO increased by 0.7 °C (TESOmax 36.5 °C [IQR 36.0;36.9]). However, the vWACA approach was not associated with a significant increase in procedure time, sedation dosage or exposure to radiation. Conclusion Very wide antral circumferential PFA of the PVs is feasible and was associated with significant larger lesion formation in comparison to conventional ostial PFA. Concomitant posterior LA wall isolation occurred in the majority of patient and did not result in a clinically significant increase of intraluminal esophageal temperatures, procedure time, sedation and radiation dosage.

Oesophageal protection during AF ablation: real world registry data and mechanisms behind the therapeutic effect of tissue cooling

Abstract Funding Acknowledgements Type of funding sources: None. Background Oesophageal protection using a dedicated device to provide controlled active thermal protection of the oesophagus during atrial fibrillation ablation has been shown to be effective at reducing endoscopically detected oesophageal lesions. Real world registry data of this device and established evidence on the effect of cooling on localized tissue after thermal injury have been under review. Purpose To determine the safety of an oesophageal temperature control device by a review of real-world registry data on its clinical use during catheter ablation procedures and to clarify basic mechanisms of its therapeutic action by a literature review of scientific studies on cooling in the context of thermal injury. Methods The United States Food and Drug Administration (FDA) Manufacturer and User Facility Device Experience (MAUDE), FDA Medical and Radiation Emitting Device Recalls, the Medicines and Healthcare products Regulatory Agency (MHRA) Medical Device Alerts and SwissMedic records of Field Safety Corrective Actions (FSCA) databases were reviewed for any device-related adverse events. A systematic literature review was conducted to clarify the findings from studies investigating the physiological processes behind the therapeutic effect of cooling after tissue thermal injury. Results Of over 20,000 oesophageal temperature control devices clinically used, 7976 were recorded as having been used for the purpose of oesophageal protection during left atrial catheter ablations. No adverse events occurred related to its use during left atrial catheter ablations. No case of clinically significant oesophageal injury was reported in a patient who had been protected by the oesophageal temperature control device. 208 research articles retrieved from PubMed and MEDLINE that met the search criteria were reviewed. The common finding in all the studies was that cooling had an anti-inflammatory and restorative effect via modulation of several immune-mediated pathways, local cellular function and genetic expression. Conclusions There have been no adverse events reported to date in real world clinical use of an oesophageal temperature control device during left atrial catheter ablations, for the purpose of active thermal protection. Literature review data suggests that there are complex biophysical and cellular effects from cooling that leads to its therapeutic effect but further work is required to define the mechanisms of action of thermal protection in this specific context.

Arrhythmia recurrence reduction with an active esophageal cooling device during radiofrequency ablation

Abstract Funding Acknowledgements Type of funding sources: None. Background As the burden of atrial fibrillation continues to rise with an aging population, there have been contrasting positions on the efficacy of left atrial ablation. While ablation techniques have continued to improve over the past decades, arrhythmia recurrence rates must be further reduced given the burden of ablation on patients. Since continuity of lesion sets has been associated with greater lesion durability, it has been theorized that the use of active esophageal cooling may facilitate greater freedom from arrhythmia. Purpose In order to investigate the association between use of active esophageal cooling and arrhythmia recurrence, we performed a multicenter retrospective study of arrhythmia recurrence rates in patients that received active cooling and compared them to those that received luminal esophageal temperature (LET) monitoring. Methods In this study, follow up data were collected from patients that underwent pulmonary vein isolation (PVI) at three separate large medical centers. Data were contained in a prospective hospital registry, a prospective physician registry, or the electronic health record, depending on the center. For each patient included, we recorded whether their ablation utilized LET monitoring or active esophageal cooling, along with their rhythm status at 1-year follow up. Rhythm status at follow-up was determined by either electrocardiogram, Holter monitor, or wearable heart rate monitor. Kaplan-Meier (KM) curves were created for freedom-from-arrhythmia at one year comparing those in the LET monitoring group to those in the active cooling group. Results Follow up data were collected from 1035 patients. There were 560 patients that received LET monitoring during their original ablation, and 475 patients that underwent active esophageal cooling. KM estimates for freedom-from-arrhythmia at one year were 42% in the LET monitored group and 65% in the actively cooled group (P&amp;lt;.001). Conclusion In this large multicenter study, there is a significant increase in freedom-from-arrhythmia at one year follow-up among patients that received active esophageal cooling as compared to those that underwent LET monitoring.

Modern technologies for radiofrequency pulmonary vein isolation. Comparison of radiofrequency balloon catheter with high power-short duration ablation in patients with paroxysmal atrial fibrillation

Abstract Funding Acknowledgements Type of funding sources: None. Background Pulmonary vein isolation (PVI) is an established therapy for symptomatic atrial fibrillation (AF). Traditional point by point ablation can be time consuming requiring advanced training. Novel radiofrequency (RF) ablation techniques sought to facilitate PVI. Point by point ablation using high power short duration (HPSD) settings has already shown to be safe and effective whereas there is paucity of data using a novel multi-electrode balloon catheter (Heliostar™, Biosense Webster, CA, USA). Purpose We aimed to assess procedure characteristics, efficacy, and safety of the Heliostar™ RF-balloon catheter in direct comparison with the latest RF ablation technique. Methods All patients undergoing PVI using the Heliostar™ between September and November 2021 were included in this ongoing single center registry. Procedural data and outcome were assessed and compared with data from patients undergoing initial PVI for paroxysmal AF with the HPSD approach from our specifically designed database. A power setting of 70W/7s (70W/5s at posterior wall) was considered as HPSD. Results A total of 51 consecutive patients (61±16 years, 49% male) were included. Of those 13 patients undergoing RF-balloon and 38 patients HPSD ablation. Baseline parameters did not differ between groups. Acute PVI was achieved in all patients. For every RF-application with the RF-balloon all necessary criteria were met: Inflation index was between 0.9 and 1.0 and a minimum of 9/10 electrodes were within impedance range. A mean of 2.8±1.4 applications per vein (LSPV 3.2±2.9, LIPV 2.6±2.5, RSPV 2.8±2.0 and RIPV 1.8±0.8) were necessary to achieve durable isolation. The mean maximum esophageal temperature was 40.2±0.8°C. When comparing procedural parameters with HPSD no statistically significant difference was seen regarding procedure duration (Heliostar™ 111±28min and HPSD 100±25min; p=0.3) and left atrial dwell time (Heliostar™ 90±23min and HPSD 80±26min; p=0.08). Fluoroscopy time (Heliostar™ 17±4min and HPSD 13±5min; p=0.005) and dose (Heliostar™ 3961±1325mGy*cm2 vs. HPSD 3153±1833mGy*cm2; p=0.04) were higher in the Heliostar™ group. No major complication occurred in both groups. A three month follow up was available for 10 patients in the Heliostar™ and for 38 patients in the HPSD group. All 10 Heliostar™ patients and 79% of the HPSD patients were free from atrial arrhythmias at follow up. Conclusion The novel multi-electrode RF-balloon has shown to be safe and effective in the first clinical routine AF ablation procedures. The tendency towards longer LA dwell times, procedure durations and the significantly higher fluoroscopy exposition in comparison with the HPSD PVI can be attributed to the learning curve applying a new ablation system. More experience is needed in the future to determine the benefits of the novel RF-balloon.

Effect of a proactive esophageal cooling device on procedure length - a multicenter comparison of persistent and paroxysmal atrial fibrillation

Abstract Funding Acknowledgements Type of funding sources: None. Background During left atrial ablation for the treatment of atrial fibrillation (AF), effective esophageal protection is essential for reducing or preventing thermal injury. Traditional methods include luminal esophageal temperature (LET) monitoring that lead to frequent pauses in the procedure when temperature alarms alert operators to dangerous temperature levels. While there have been recent studies that demonstrate an association between active esophageal cooling and a reduction in procedure duration regardless of AF type, these retrospective studies have been conducted at single or joint centers which may lead to confounding from other time-saving variables that have changed over time. Purpose Consequently, we sought to perform a large-scale multicenter comparison to better elucidate the association between procedure length and the use of active cooling in patients with persistent and paroxysmal atrial fibrillation. Methods In this study, we collected data from three large hospital centers, one hospital-maintained registry, one physician-maintained registry, and one through EHR data review and aggregated in groups separated by AF type as well as whether the patients received active cooling or LET monitoring. We then compared median procedure durations in each group. Results There were a total of 753 patients included in this study. Of the 360 patients with paroxysmal AF, 179 received active esophageal cooling while 181 underwent LET monitoring. In the persistent AF group with 393 patients, 157 received active esophageal cooling and 236 underwent LET monitoring. Among patients with paroxysmal AF, the median mean procedure duration was 137 minutes in the LET monitored group, and 90 minutes in the actively cooled group with an overall reduction of 47 minutes (P&amp;lt;.001). In patients with persistent AF, the median procedure duration was 148 minutes in the LET monitored group and 94 minutes in the actively cooled group with an overall reduction of 54 minutes (P&amp;lt;.001). The relative reduction as a percent of total procedure time was 34%, and 36%, for paroxysmal and persistent AF cases, respectively. Conclusion In this large multicenter review, there is a significant reduction in procedure length when using active esophageal cooling, regardless of AF type.

Heat exposure limits for young unacclimatized males and females at low and high humidity

ABSTRACT Little is known about the separate and combined influences of humidity conditions, sex, and aerobic fitness on heat tolerance in unacclimatized males and females. The purpose of the current study was to describe heat tolerance, in terms of critical WBGT (WBGTcrit), in unacclimatized young males and females in hot-dry (HD) and warm-humid (WH) environments. Eighteen subjects (9M/9F; 21 ± 2 yr) were tested during exercise at 30% V̇O2max in a controlled environmental chamber. Progressive heat stress exposures were performed with either (1) constant dry-bulb temperature (Tdb) of 34 and 36 °C and increasing ambient water vapor pressure (Pa) (Pcrit trials; WH), or (2) constant Pa of 12 and 16 mmHg and increasing Tdb (Tcrit trials; HD). Chamber Tdb and Pa, and subject esophageal temperature (Tes), were continuously monitored throughout each trial. After a 30-min equilibration period, progressive heat stress continued until subject heat balance could no longer be maintained and a clear rise in Tes was observed. Absolute WBGTcrit, WBGTcrit adjusted to a metabolic rate of 300W (WBGT300), and the difference between WBGTcrit and occupational exposure limits (OEL; ΔOEL) were assessed. WBGTcrit, WBGT300, and ΔOEL were higher in WH compared to HD (p < 0.0001) for females but were the same between environments for males (p ≥ 0.21). WBGTcrit was higher in females compared to males in WH (p < 0.0001) but was similar between sexes in HD (p = 0.44). When controlling for metabolic rate, WBGT300 and ΔOEL were higher in males compared to females in WH and HD (both p < 0.0001). When controlling for sex, V̇O2max was not associated with WBGT300 or ΔOEL for either sex (r ≤ 0.12, p ≥ 0.49). These findings suggest that WBGTcrit is higher in females compared to males in WH, but not HD, conditions. Additionally, the WBGTcrit is lower in females, but not males, in HD compared to WH conditions.

PO-615-08 SINGLE SENSOR VERSUS MULTI-SENSOR ESOPHAGEAL MONITORING: WHAT ARE WE MISSING?

Esophageal temperature monitors are often used to decrease risk of esophageal injury during atrial fibrillation ablation. Multi-sensor monitors have been shown to have a superior thermodynamic profile in radiofrequency ablation, but there is limited data on single versus multi-electrode temperature discrepancies in cryoballoon ablation. We aim to evaluate temperature differences in the Circa S-Cath, a multi-sensor esophageal probe, to investigate its potential benefits over a single sensor probe in cryoablation. A total of 15 patients underwent cryoballoon ablation for atrial fibrillation under general anesthesia. A Circa probe was placed oropharyngeally after intubation. The Circa Esophageal Temperature Monitor has 12 sensors total located 8mm apart. Each sensor has a radiopaque marker and collects a temperature to the nearest 10th of a degree every half second. Position of the Crica probe could be adjusted under fluoroscopy. In the total of 15 patients, a minimum esophageal temperature below 25 °C was recorded in 8 cases during cryoablation. The lowest esophageal temperature did not occur in the same sensor for all cases or even freezes in the same patient. Sensor 7 recorded the coldest temperature in 7/15 of these freezes, Sensor 8 recorded 3/15, Sensor 10 recorded 2/15, and Sensors 4, 5, and 10 recorded one each. When compared to neighboring sensors, the largest difference between neighboring sensors was 13.14 degrees, with a range of 5.6 to 19.9 degrees. The disparity between neighboring temperature sensors suggest that single sensor probes are insufficient to detect the lowest temperature of the esophagus. Continuation of cryoablation to very low temperatures could increase risk of collateral injury to the esophagus. Use of multi-sensor temperature probes helps in accurately reflecting the coldest temperature point of the esophagus during cryoablation. Similar discrepancy may also be seen in radiofrequency ablation.

The Effect of Increasing Levels of Hyperthermia on Autophagy in Peripheral Blood Mononuclear Cells from Young Adults

Exposure to an elevated state of hyperthermia is associated with heat‐induced cytotoxicity, thereby resulting in impaired cellular function. Cellular dysfunction during heat stress leads to the initiation of systemic inflammation and apoptotic cell death, which if left unabated, can cause tissue damage and death. To counter heat‐induced cellular injury, cells employ the vital mechanism of autophagy which acts to prevent the accumulation of toxic protein aggregates and dysfunctional organelles to promote cellular survival. In our recent ex vivomodel, we demonstrated that the process of autophagy is activated during exposure to increased temperatures (37‐41°C) in peripheral blood mononuclear cells (PBMCs) from young adults which acts to suppress heat‐induced apoptotic cell death. Despite this, the dose‐dependent autophagic response to heat stress has yet to be evaluated in an in vivo human model and thus the relationship between elevations in core body temperature (Tcore) and autophagy have yet to be established in humans. Therefore, we sought to extend upon our previous work by assessing if in vivorises in Tcore are associated with greater autophagic activation in healthy young adults. We evaluated the hypothesis that in parallel to elevations in Tcore(indexed by esophageal temperature), greater autophagic initiation would occur in a dose‐dependent manner in young adults during immersion in mild to very warm water. To assess this hypothesis, on separate days 6 young adults (mean [SD] 22 [3] years; 3 women) were immersed (up to the clavicle) in water set at a temperature to clamp Tcore at either thermoneutral (TN, 37°C), 38°C, or 39°C for 60‐min. Autophagy was characterized in PBMCs prior to and immediately post‐water immersion, as well as following 3‐h of seated recovery. Western blot was used to assess autophagy proteins microtubule associated protein 1 light chain 3 beta (LC3)‐II and sequesterome‐1/p62 (p62). All proteins were normalized to β‐actin and reported as fold change relative to baseline. Data were compared via a two‐way repeated measures ANOVA with Fisher’s LSD (α=0.05). No changes in either LC3‐II or p62 were observed during TN, indicating no time‐dependent changes in autophagy (all p≥0.28). Immediately following the 38°C clamp, LC3‐II increased (1.56 [0.32]; p=0.02) and p62 decreased (0.52 [0.30]; p=0.049) from baseline, with both proteins returning to basal levels within 3‐h (both, p≥0.22). Similarly, LC3‐II increased (1.90 [0.70]; p=0.04) and p62 decreased (0.58 [0.21]; p=0.03) immediately after clamping Tcore at 39°C, however LC3‐II remained elevated above baseline at 3‐h (2.54 [1.08]; p=0.03) while p62 did not differ from pre‐immersion levels at the end of recovery (p=0.57). Given LC3‐II accumulation and p62 degradation indicate elevated autophagy, our preliminary findings indicate greater autophagy during increasing levels of hyperthermia in healthy young adults. Further, we showed increased reliance on autophagy to restore cellular homeostasis after exposure to an elevated state of hyperthermia of 39°C, although the mechanism of activation is unclear.

PO-695-08 PULMONARY VEIN ISOLATION (PVI) AND POSTERIOR WALL ISOLATION (PWI) FOR ATRIAL FIBRILLATION USING POINT-BY-POINT PULSED ELECTRIC FIELDS: SPACE AF ACUTE RESULTS

Pulsed electrical field (PEF) has been used for pulmonary vein isolation (PVI). The CENTAURI System enables PEF ablation via standard contact force ablation catheters. The point-by-point clinical workflow may enable treatment beyond PVI, including posterior wall isolation (PWI). SPACE AF study is evaluating feasibility and safety of PVI with PWI using PEF in patients with high burden paroxysmal and persistent AF. CENTUARI PEF System (Galaxy Medical) and a focal contact force sensing catheter (ThermoCool ST, Biosense Webster) were used for PEF ablation for wide antral PVI with PWI. Operators chose one of three doses (19A, 22A, 25A) with contact force of >5g. Primary efficacy outcome was entrance/exit block of all pulmonary veins (PVs) after a 20-minute wait. Composite safety endpoint comprised of pre-specified adverse events including microbubble formation on intracardiac echo (ICE), ST-segment changes, phrenic nerve palsy, esophageal temperature rises, NIH stroke scale (NIHSS) changes, PV stenosis, and silent cerebral lesions after PEF ablation. CT of the PVs will be done at 3 months. Cranial MRI was done at 24 hours in a subset of patients. Secondary endpoint includes recurrence of AF post-ablation at 6 and 12 months with serial Holter monitoring. SPACE AF will report on 30 patients. Thus far, 12 patients (58% Male, age 55.8±10.5 years) have been treated. Acute PVI and PWI was achieved in all 12 patients (100%). An average of 113.8±12.1 applications were delivered per patient. Energy settings were 32% at 22A and 68% at 25A. There were no ST-segment changes, microbubble formations, phrenic nerve injuries, or esophageal temperature rises during PEF ablation. There were no changes to NIHSS pre- vs. post-procedure. Three (3) patients have participated in the cranial MRI sub-study, and all had negative DWI and FLAIR post-procedure. No patients experienced procedure- or device-related AEs at 30 days. PV anatomy will be assessed at 90 days. Long-term AF recurrence outcomes will be assessed at 6-month and 12-month follow-up via 48-hour Holter. Cardiac ablation using PEF delivered through standard focal catheters is safe and acutely successful when performing PWI after PVI. Further results on additional patients and AF recurrence will be presented.

CA-528-03 A REGISTRY REVIEW UPDATE OF 7120 CATHETER ABLATIONS FOR ATRIAL FIBRILLATION USING A DEDICATED ESOPHAGEAL TEMPERATURE CONTROL DEVICE FOR PROTECTION

Esophageal protection using a dedicated device to provide controlled active thermal protection of the esophagus during atrial fibrillation ablation has been shown to be effective. Randomized evidence from the IMPACT trial showed an 83.4% reduction in endoscopically detected esophageal lesions compared to standard care. Real world registry data of this device has been under review. To determine the safety of an esophageal temperature control device by an updated review of real-world registry data on its clinical use and any reported device-related adverse events. The following databases were reviewed for any reported esophageal temperature control device-related complications: The United States Food and Drug Administration (FDA) Manufacturer and User Facility Device Experience (MAUDE), FDA Medical and Radiation Emitting Device Recalls, the Medicines and Healthcare products Regulatory Agency (MHRA) Medical Device Alerts and SwissMedic records of Field Safety Corrective Actions (FSCA). An internal registry (post-marketing follow up) database maintained by the manufacturer of the device was used to quantify the number used for each indication. Reported events underwent an updated review including any instances of device-related adverse events when used during catheter ablations. Of the 20,000 oesophageal temperature control devices used, 7120 were recorded as having been used for the purpose of esophageal protection during left atrial catheter ablations. A total of 5 events associated with the device were identified, all from the MAUDE database. Three were from 2017, one from 2018, and one from 2019. All involved its use in critical care or trauma patients and were related to user error or contraindicated patient selection; none resulted in serious harm to the patient. No adverse events occurred related to its use during left atrial catheter ablations. No case of clinically significant esophageal injury was reported in a patient who had been protected by the esophageal temperature control device. Real world registry data has shown no adverse events reported to date in 7120 uses of an esophageal temperature control device during left atrial catheter ablations, for the purpose of active thermal protection.

PO-681-08 REDUCED PROCEDURAL DURATION WITH PROACTIVE ESOPHAGEAL COOLING DURING LEFT ATRIAL ABLATION: A MULTICENTER ANALYSIS

Reductions in left atrial ablation procedure duration can improve lab efficiency, patient satisfaction, and overall safety. Pauses and interruptions of lesion placement due to luminal esophageal temperature (LET) rises during pulmonary vein isolation (PVI) can disrupt workflow and increase procedure time. Proactive esophageal cooling eliminates the need for lesion interruption by preventing heat stacking and obviating the need for temperature monitoring. Avoiding premature pauses of radiofrequency (RF) lesion placement may also reduce PVI procedure duration.

Calculated parameters of luminal esophageal temperatures predict esophageal injury following conventional and high-power short-duration radiofrequency pulmonary vein isolation.

Luminal esophageal temperature (LET) monitoring is not associated with reduced esophageal injury following pulmonary vein isolation (PVI). Detailed analysis of (the temporal and spatial gradients of) LET measurements may better predict the risk for esophageal injury. Between January 2020 and December 2021, LET maxima, duration of LET rise above baseline, and area under the LET curve (AUC) were calculated offline and correlated with (endoscopy and endoscopic ultrasound detected) esophageal injury (i.e., mucosal esophageal lesions [ELs], periesophageal edema, and gastric motility disorders) following PVI using moderate-power moderate-duration (MPMD [25-30 W/25-30s]) and high-power short-duration (HPSD [50 W/13s]) radiofrequency (RF) settings. 63 patients (69 ± 9 years old, 32 male, 51 MPMD and 12 HPSD) were studied. The esophageal injury was frequent (40% in both groups), mucosal ELs were more common with MPMD, and edema was frequently observed following HPSD. RF-duration, total RF-energy at the left atrial (LA) posterior wall, and distance between LA and esophagus were not different between patients with/without esophageal injury. In contrast, to LET and LET duration above baseline, AUC was the best predictor and significantly increased in patients with esophageal injury (3422 vs. 2444 K. s). For both ablation strategies, AUC of the LET curves best predicted esophageal injury. HPSD is associated with similar rates of esophageal injury when (mostly subclinical) periesophageal alterations (that are of unclear clinical relevance) are included. Whether integration of these calculated LET parameters is useful to prevent esophageal injury remains to be seen.