bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 17337: Late Gadolinium Enhancement Cardiovascular Magnetic Resonance Imaging Characteristics Predict the Yield of Endomyocardial Biopsy in Patients With Suspected Cardiac Sarcoidosis
Authors: Chen Ko-Hsuan , Kazmirczak Felipe , Okasha Osama , Farzaneh-Far Afshin , Shenoy Chetan
Published: July 2021

Introduction:
In patients with suspected cardiac sarcoidosis, a definitive diagnosis of the condition can only be made in the presence of non-caseating granuloma on histological examination of myocardial tissue with no alternative cause identified. However, endomyocardial biopsy (EMB) has a low sensitivity - attributed to the focal nature of the disease - with a reported yield of <25% in patients with a clinical diagnosis of sarcoidosis. We hypothesized that late gadolinium enhancement (LGE) characteristics on cardiovascular magnetic resonance imaging (CMR) would be associated with the diagnostic yield of EMB for suspected cardiac sarcoidosis.

Methods:
We studied 52 patients with suspected cardiac sarcoidosis that underwent both CMR and EMB and investigated associations between the EMB yield and LGE CMR characteristics: presence of LGE, presence of LGE in the septum, presence of LGE on the right ventricular (RV) side of the septum, extent of LGE, and extent of LGE on the RV side of the septum. The extent of LGE was measured using the 5SD method. The extent of LGE on the RV side of the septum was measured by tracing the RV border of the septum on all short-axis LGE images, and expressed as a percent of the total RV border with LGE.

Results:
Of 52 patients, non-caseating granulomas were noted in 9 (17.3%). Comparison of the markers between patients with and without positive EMB is provided. Receiver Operating Characteristic (ROC) analyses showed the largest area under the curve (AUC) for the extent of LGE on the RV side of the septum (0.92). A cut-off of >14.7% of LGE on the RV side of the septum had a sensitivity of 100% and specificity of 79% to predict the yield of EMB.

Conclusions:
In patients with suspected cardiac sarcoidosis undergoing EMB, the presence of LGE has 100% sensitivity but a low specificity for predicting the yield of EMB. Among LGE characteristics, the extent of LGE on the RV side of the septum has the highest AUC, and a cut-off of >14.7% predicts a positive EMB with 100% sensitivity and 79% specificity. LGE CMR characteristics can help improve the yield of EMB in patients with suspected CS.
Abstract 17348: Privileged or Not?: Immunologic Properties of Allogenic Endothelial Progenitor Cell-Derived Extracellular Vesicles
Authors: Chung Jennifer J , Zaman Samir , Gordon Jonathan , Arisi Maria F , Li Elizabeth , Chen Carol W , Gaffey Ann C , Atluri Pavan
Published: July 2021

Introduction:
Extracellular vesicles (EV) from allogeneic progenitor cells are considered safe for treatment of ischemic myocardium based on the assumption of immune-privilege. However no studies have rigorously examined the local immune response following pooled-donor EV therapy. Understanding the specific immune reaction to endothelial progenitor cell-derived EVs (EEVs) has critical implications for clinical translation to treatment of acute myocardial infarction (MI).

Aim:
We aim to characterize the immune cells that respond acutely to injected intramyocardial delivery of pooled donor EEVs using in-depth flow cytometric (FCM) analysis.

Methods:
EEVs were isolated from pooled, primary bone-marrow EPCs from male Wistar rats. Uptake of DiI labeled EEVs by rat endothelial cells, cardiac fibroblasts, and myoblasts was assessed
in vitro
.
In vivo
immune response to EEVs in rats was studied after intramyocardial injection of PBS and PBS-EV. Left ventricular (LV) tissue digested at D1 and D6 was analyzed by 9-Color FCM for detection and differentiation of T, B, and NK cells, neutrophils, and monocytes. Local immune cell infiltration was assessed by H&E staining at D5 post-injection.

Results:
All cells tested had robust EEV internalization of DiI stain. H&E showed immune cell infiltration near the injection site, but no gross difference in EEV vs. PBS at D5. In-depth FCM of the LV at D1 and D6 post injection showed marked decrease in lymphocyte infiltration, but increased percentage of NK, B and CD8+ T cells from D1 to D6. EEVs did not significantly change the percentage of lymphocyte infiltration vs. PBS at D1 or D6.

Conclusions:
FCM can be successfully used for in-depth characterization of cardiac immune cell-types in rat models of allogeneic myocardial therapy. Allogeneic EEV therapy demonstrates robust, rapid internalization into the major cardiac cell types and elicit minimal additional innate or acquired immune response compared to saline injection.
Abstract 17357: Magnetic Resonance Imaging Detected Intraplaque Hemorrhage and Expansive Remodeling in Superficial Femoral Artery
Authors: Sun Jie , Zhao Xue-Qiao , Canton Gador , Balu Niranjan , Isquith Daniel , Hippe Daniel , Yuan Chun , Hatsukami Thomas
Published: July 2021

Introduction:
Compared to coronary and carotid arteries, there is much less knowledge on atherosclerotic plaque characteristics and their clinical relevance in lower-extremity arteries. Magnetic resonance (MR) vessel wall imaging allows for in vivo detection of intraplaque hemorrhage (IPH), which has been consistently associated with increased risks for clinical events in coronary and carotid artery disease.

Objective:
In a pilot study, we sought to estimate the prevalence of IPH in peripheral artery disease and examine plaque progression in the presence of IPH.

Methods:
Ten patients with ankle brachial index <0.90 in one or both legs were recruited. A 3D MR imaging protocol with a large coverage (30 or 45 cm in the head-feet direction) and isotropic resolution (voxel size: 0.8x0.8x0.8 mm
3
) was used to scan bilateral legs in the coronal plane from the common femoral artery bifurcation to the popliteal artery at baseline and 6 months later. Images were reformatted into axial slices for detailed visualization of vessel wall. Following previous publications on carotid MRI, IPH was detected as hyperintense signals on heavily T1-weighted images. Superficial femoral artery (SFA) segments (3 cm in length) with IPH were identified, of which lumen and outer wall were segmented on black-blood images (motion-sensitized flow suppression for improved vessel wall delineation) to measure plaque progression and remodeling. Image analysis was performed in a blinded fashion without knowing time relationship between serial images.

Results:
Twenty SFAs were analyzed. After excluding 4 arteries with total occlusion, 5 out of the 16 arteries (31%) or 50% of the subjects showed IPH in 1 or more SFA segments. After 6 months, there was significant progression in vessel wall area in SFA segments with IPH (mean ± standard deviation: 43.5 ± 13.9 mm
2
versus 47.3 ± 17.3 mm
2
, p=0.045), which resulted in outer wall expansion (mean [95% confidence intervals]: +3.9 mm
2
[+0.4, +7.4], p=0.035) rather than lumen reduction (-0.02 mm
2
[-2.6, +2.5], p=0.99).

Conclusions:
MR vessel wall imaging revealed that IPH is likely a common feature in femoral atherosclerosis. SFA segments with IPH showed expansive remodeling in 6 months, of which the clinical significance needs to be further studied.
Abstract 17362: A Multidisciplinary Heart Team Approach to High Risk Transvenous Pacemaker and Defibrillator Lead Extraction Improves Mortality
Authors: Aleong Ryan G , Zipse Matthew , Tompkins Christine , Seres Tamas , Fullerton David , Aftab Muhammad
Published: July 2021

Introduction:
There is a risk of serious complications with high-risk lead extraction (LE) that may increase mortality. Current guidelines do not provide definitive guidance on collaborative involvement of cardiac surgery as compared to other procedures such as TAVR procedures. We report a single center experience of the benefits of a collaborative approach between cardiac surgery and cardiac electrophysiology (EP).

Hypothesis:
MDHT will improve outcomes in LE

Methods:
High risk lead extractions had dwell times of at least 4 years for pacemaker leads and 2 years for ICD leads. A multidisciplinary heart team (MDHT) was created based on the TAVR model that includes a combined lead management clinic and a monthly multidisciplinary conference. Prior to MDHT creation, high risk lead extractions were performed either in the hybrid operating room (OR) and cardiology procedure lab with a surgeon on call as needed. After the MDHT creation all cases were performed in the hybrid operating room by a cardiac surgeon, cardiac anesthesiologist and EP together with an interventional radiologist readily available.

Results:
Prior to MDHT, 169 patients underwent 344 leads extractions. There were six major procedural complications (3.6%) that included 2 procedural deaths (1.2%) during that period (SVC tear, Tricuspid valve avulsion). Following the creation of MDHT, there have been 47 cases performed with 85 leads extracted. There have been two complications requiring surgical repair (one SVC laceration, one RV laceration), which were surgically repaired. With the creation of a MDHT, the rate of major complications was unchanged (Pre vs. Post MDHT 3.6% vs. 4.3%) but there was a lower mortality rate (Pre vs. Post MDHT 1.2% vs. 0%).

Conclusions:
High risk lead extraction had a fixed complication rate at our institution however a MDHT decreased mortality. A structured multidisciplinary approach, involving EP and cardiac surgery, decreased mortality in a medium sized lead extraction center and should be considered at all centers.
Abstract 17367: Infusion of the Ketone Body β-Hydroxybutyrate Improves Left Ventricular Systolic Function in an Animal Model of Heart Failure With Reduced Ejection Fraction
Authors: SantosGallego Carlos G , Requena-Ibanez Juan Antonio , San Antonio Rodolfo , Ishikawa Kiyotake , Picatoste Belén , Garcia-Ropero Alvaro , Sanz Javier , Hajjar Roger , Fuster Valentin , Badimon Juan J
Published: July 2021

Introduction:
In vitro, ketone bodies (KB) are the most energetically efficient fuel for myocardium. Ex vivo, KB infusion in the perfusion medium of working rat hearts increases the heat of combustion (produced energy) by 31%. However, there is no report about the in vivo effects of KB on LV function. We hypothesized that KB infusion in HFREF would improve energy production and thus LV systolic function.

Methods:
HFREF was induced in 15 pigs by 2-hour balloon occlusion of LAD: proximal LAD (n=8, severe HREF) and mid LAD (n=7, moderate HFREF). At 2 months, LV systolic function was evaluated during saline infusion and during infusion of the KB β-hydroxybutyrate. Severe HFREF animals underwent cardiac MRI for baseline LVEF, feature tracking strains, and contractile reserve (ΔLVEF under dobutamine 5μg/kg/min). Moderate HFREF pigs underwent invasive hemodynamic assessment (dP/dt) and 3D-echocadiography (3D-LVEF and 3D-strains). Simultaneous sampling from coronary artery and coronary sinus was performed to measure myocardial fuel consumption.

Results:
Proximal and mid LAD occlusion resulted in severe and moderate LV systolic dysfunction, respectively. In the severe HFREF, ketone infusion improved baseline LVEF, feature-tracking strains (both longitudinal and circumferencial strain), and contractile reserve. In the moderate HFREF, ketone infusion improved 3D-LVEF, 3D-strains and dP/dt (Table). Ketone infusion switched myocardial metabolism from glucose to ketone consumption.

Conclusions:
Continuous infusion of the KB hydroxybutyrate improves LV systolic function independent of LV systolic dysfunction severity via a shift in myocardial fuel metabolism away from glucose oxidation (energy inefficient) toward a more energy-efficient fuel like KB. This effect can explain the mechanism of action of the benefits of SGLT2 inhibitors in heart failure, as empagliflozin-induced mild kyperketonemia may increase LV systolic function and thus improve patient outcomes.
Abstract 17384: Cardiac-Specific Overexpression of Human Mutant Desmoplakin in Mice Disrupts Cardiac Voltage-Gated Sodium Channel Expression
Authors: Turdi Subat , Towbin Jeffrey A
Published: July 2021

Introduction:
Arrhythmogenic cardiomyopathy (AC) is characterized by bi-ventricular dilation, fibro-fatty infiltration and life-threatening arrhythmias. Disruptions in cardiac voltage-gated sodium channel (Nav1.5) expression and function are known to cause arrhythmias. We have demonstrated that cardiac-specific overexpression of human mutant desmoplakin (DSP, Tg-R2834H) in mice leads to AC. However, whether mutant DSP expression in the heart affects the Nav1.5 distribution and function are unknown

Hypothesis:
Here, we tested whether Nav1.5 localization and expression are altered in the R2834H-Tg mouse hearts.

Methods:
Primary cardiomyocytes and frozen myocardial sections from non-transgenic (NTg), wild-type DSP (Tg-DSP) and Tg-R2834H mice were used for immunofluorescence studies to assess subcellular localization of DSP, desmin, Nav1.5, Cx43, plakoglobin and β-catenin. Western blot and qPCR were used for quantitative analysis.

Results:
Double staining of cardiomyocytes from NTg mice with DSP and Nav1.5 revealed that Nav1.5 was colocalized with DSP at the intercalated discs (IDs). In contrast, Tg-R2834H cardiomyocytes exhibited marked increase of mutant DSP expression at the IDs concomitant with a reduction in Nav1.5 immunoreactive signals. Tg-R2834H cardiomyocytes also revealed an aberration of DSP and desmin colocalizations at the IDs. There were not obvious differences in Cx43 expression between the genotypes, although the redistribution of Cx43 from the IDs to the sarcolemma was evident in Tg-R2834H cardiomyocytes. qPCR results correlated with reduced Nav1.5 mRNA expression in the Tg-R2834H mouse hearts.

Conclusions:
Defective DSP protein expression in the heart disrupts Nav1.5 localization and expression, implying an interaction between DSP and Nav1.5 to orchestrate normal mechanical and electrical coupling. Further electrophysiology studies to assess whole-cell Na
+
currents in these cardiomyocytes will provide insight into DSP and Nav1.5 interaction.
Abstract 17391: Use of Contrast-Enhanced Echocardiography for Evaluating Pulmonary Artery Pressure
Authors: Lee Lauren , Kinno Menhel , Schultz Robert , Kane Bonnie , Cascino Gregory , Maganti Kameswari
Published: July 2021

Introduction:
Pulmonary artery systolic pressure (PASP) can be derived from maximum tricuspid regurgitation velocity (TRV) obtained from echo using a modified Bernoulli equation. However, PASP from an unenhanced echo only modestly correlates to invasively measured PASP. This study evaluates whether the accuracy of PASP from an echo can be improved by using contrast agents.

Methods:
Ninety consecutive patients undergoing clinically indicated right heart catheterization were recruited to perform simultaneous echo. TRV was measured in an echo unenhanced (UE), with agitated saline (AgS), and with echo contrast (EC) (routinely injected centrally, and peripherally in 21 patients). PASP was then calculated using the formula PASP=4(TRV
2
)+RAP, where RAP was estimated on echo by inferior vena cava collapsibility. Data was analyzed using paired t-test and linear regression (JMP Pro13).

Results:
Average age was 54 (±13) years with 58% males, 73% heart transplant recipients, and 38% with pulmonary hypertension. UE PASP was significantly lower than RHC PASP with a mean difference of -6.09 mm Hg (p<0.001) and correlation coefficient of 0.57 (p<0.001). In comparison, AgS PASP had a smaller mean difference of 0.41 mm Hg (p=0.641) and a higher correlation coefficient of 0.73 (p<0.001). EC-enhanced echo also yielded a smaller mean difference (central: -1.82 mm Hg with p=0.049; peripheral: -3.21 mm Hg with p=0.095) and an even higher correlation coefficient (central: r=0.74; peripheral: r=0.81). Number of patients with accurate PASP from echo (defined as PASP difference <10 mm Hg between echo and RHC) was improved from 65% (UE) to 77% (AgS), 82% (EC-central), and 71% (EC-peripheral).

Conclusion:
Echo with agitated saline yielded the closest mean PASP compared to invasivePASP, whereas echo with peripherally administered EC yielded the highest correlation coefficient. Echo enhancement with either Ags or EC can improve the accuracy of the estimated PASP compared to UE studies.
Abstract 01: Dispatching Lay Rescuers Through a Smartphone Application is Associated With Increased Bystander Defibrillation in Out-of-Hospital Cardiac Arrest
Authors: Andelius Linn , Malta Hansen Carolina , Lippert Freddy , Karlsson Lena , Torp-Pedersen Christian , Gislason Gunnar , Folke Fredrik
Published: July 2021

Introduction:
Survival after out-of-hospital cardiac arrest (OHCA) is dependent on early defibrillation. To increase bystander defibrillation in OHCAs, a first-responder program dispatching lay rescuers (Heart Runners) through a smartphone application (Heart Runner-app) was implemented in the Capital Region of Denmark. We investigated the proportion of Heart Runners arriving prior to the Emergency Medical Services (EMS) and rates of bystander defibrillation.

Methods:
The Capital Region of Denmark comprises 1.8 mil. inhabitants and 19,048 Heart Runners were registered. In cases of suspected OHCA, the Heart Runner-app was activated by the Emergency Medical Dispatch Center. Up to 20 Heart Runners < 1.8 km from the OHCA were dispatched to either start cardiopulmonary resuscitation (CPR) or to retrieve and use a publicly accessible automated external defibrillator (AED). Through an electronic survey, Heart Runners reported if they arrived before EMS and if they applied an AED. OHCAs where at least one Heart Runner arrived before EMS were compared with OHCAs where EMS arrived first. All OHCAs from September 2017 to May 2018, where Heart Runners had been dispatched, were included.

Results:
Of 399 EMS treated OHCAs, 78% (n=313/399) had a matching survey. A Heart Runner arrived before EMS in 47% (n=147/313) of the cases, and applied an AED in 41% (n=61/147) of these cases. Rate of bystander defibrillation was 2.5-fold higher compared to cases where the EMS arrived first (Table 1).

Conclusions:
By activation of the Heart Runner-app, Heart Runners arrived prior to EMS in nearly half of all the OHCA cases. Bystander defibrillation rate was significantly higher when Heart Runners arrived prior to EMS.
Abstract 101: PHLPP Inhibitory Peptide Administered During CPR Improves Survival After Prolonged Cardiac Arrest
Authors: Li Jing , Zhu Xiangdong , Lee Chunpei , Tain Rong-Wen , Cai Kejia , Vanden Hoek Terry
Published: July 2021

Introduction:
Active cooling is more effective than targeted temperature management in improving sudden cardiac arrest (SCA) survival, but can be difficult to implement clinically. We are developing drugs that mimic cooling effects without the need for physical cooling. Cooling protection is mediated by Akt activation. PH domain and Leucine rich repeat Protein Phosphatases (PHLPP) is a phosphatase that negatively regulates Akt. We developed a cell-permeable peptide TAT-PHLPP9c that inhibits PHLPP and reaches heart and brain within 5 min of intravenous administration.

Hypothesis:
We hypothesize that TAT-PHLPP9c improves outcomes following SCA. This protection involves the improved early metabolic recovery.

Methods:
C57BL6 mice (n=20) were randomized to receive peptide treatment and appropriate blinding was ensured. A 12 min asystolic arrest was induced with KCl. CPR was started along with TAT-PHLPP9c (7.5 mg/kg) via i.v. Survival was evaluated. Cerebral blood flow (CBF) and metabolic chemical exchange saturation transfer (CEST) contrast were measured with endogenous and dynamic arterial spin labeling (ASL) and CEST MRI respectively. Glucose utilization was assessed by pyruvate dehydrogenase (PDH) phosphorylation and ATP generation. Further, blood taurine and glutamate were measured.

Results:
Compared to control, TAT-PHLPP9c significantly improved ROSC rates. 3 ROSC mice in the control group died within 10 min while 8 out of 10 ROSC mice in the treatment group survived over 1 h and 4 mice survived to 4 h despite a 12-min arrest. Progressively increased CBF and metabolic CEST contrast were observed in the treated mice compared to controls. p-PDH was decreased by TAT-PHLPP9c (increased activity) at 15 min post-ROSC in both heart and brain. ATP generation was replenished with the peptide treatment. Plasma taurine and glutamate concentrations was reduced by TAT-PHLPP9c as early as 5 min post-ROSC. Further, higher levels of taurine and glutamate were detected in the non-survivors than the survivors.

Conclusions:
This novel treatment strategy may have a high translational potential to reproduce critical outcomes of CPR cooling without physical cooling.
Abstract 11: Beneficial Effects of Hcn Inhibitor on Post-Resuscitation Myocardial Dysfunction in a Porcine Model of Cardiac Arrest
Authors: Yang Min , Hua Tianfeng , Chen Limin , Zou Yangyang
Published: July 2021

Introduction:
Previous studies have demonstrated that β-adrenergic blocking agents improved neurologic function and the rate of survival. However, its negative inotrope effects that increased the severity of PRMD (post-resuscitation myocardial dysfunction). We studied whether ivabradine (IVA) improves PRMD in a cardiac arrest model.

Hypothesis:
we hypothesized that the rational use of IVA would improve severity of PRMD and prognosis in a porcine model of CA.

Methods:
Ventricular fibrillation was induced and untreated for 8 minutes in anesthetized domestic swine while defibrillation was attempted after 6 minutes of cardiopulmonary resuscitation. Hemodynamic parameters were monitored continuously after ROSC. Mitral E/A ratio and E/e′ velocity ratio were assessed by echocardiography at Baseline, PR 1, 2, 4, 8 and 24hours after ROSC. The levels of cardiac troponin I (cTnI) and N-terminal pro-brain natriuretic peptide (NT-proBNP) were measured by ELISA method at Baseline, PR 1, 4 and 24hours. The animals were euthanized 24h after ROSC, and the cardiac tissue was removed for histopathological analysis.

Results:
Heart rate in the IVA group reduced significantly compared with the control group (all
P
< 0.05) at PR 1, 2, 4, 8hours. Animals subjected to IVA groups presented significantly better post-resuscitation relaxation function (E/A, E/e′) than those in the Placebo groups (all
P
< 0.05) (Figure1). IVA group had a lower cTnI and NT-proBNP levels than Placebo group at PR 1, 4 and 24hours (all
P
< 0.05) (Figure1). Biopsy score in the IVA group was significantly lower at PR 24hours when compared with the Placebo group (all
P
< 0.05) (Figure2).

Conclusions:
Heart rate reduction with IVA, improved left ventricular diastolic function and reduced myocardial injury.
Abstract 116: Delta Neutrophil Index as a Useful Prognostic Marker in Pediatric Cardiac Arrest
Authors: Yoon Seo Hee , Ahn Jong Gyun
Published: July 2021

Introduction:
Patients resuscitated after enduring cardiac arrest (CA) experience post-cardiac arrest syndrome, which mimics the physiologic derangement consistent with observations of severe sepsis. The delta neutrophil index (DNI), which reflects a fraction of circulating immature granulocytes, has been reported to be strongly associated with increased mortality in systemic inflammation, also in adult patients after CA. However, pediatric CA is different from adult CA in etiology or early pathophysiology. In this study we evaluated the prognostic significance of the DNI in terms of early mortality after CA in children.

Methods:
We retrospectively identified consecutive patients (≤18 years) with CA who received chest compression for ≥2 min from January of 2012 to January of 2018. Patients who survived at least 24 h after undergoing chest compression were included in the analysis. The DNI was determined on each day following the incidence of CA. The outcome of interest was the 30-day mortality.

Results:
A total of 85 patients who had a CA were included in the study (survival group; n=55, non-survival group; n=30). The median value of the DNI on day 1 (24 hours after CA) was 1.4% (interquartile range [IQR] 0-4.7%) in the survivor group, and 15.1% (IQR 6.7-28.7%) in the non-survivor group. The difference was statistically significant (
P
< 0.001). The receiver operating characteristics analysis revealed a cut-off that predicted a 30 day-mortality, was a DNI on day 1 > 4.7% (area under the curve 0.816; 95% CI (0.713 to 0.895);
P
< 0.001). The Kaplan-Meier survival analysis revealed, the probability of survival was significantly lower in patients with DNI > 4.7% on day 1 (log-rank test;
P
< 0.001).

Conclusions:
The DNI level can be considered a useful indicator for predicting early prognosis in pediatric cardiac arrest patients
Abstract 12: Cerebrovascular Pressure Reactivity Predicts Outcome in Diffuse Hypoxic-Ischemic Brain Injury
Authors: Balu Ramani , Baghshomali Sanam , Abella Benjamin S , Kofke William A
Published: July 2021

Introduction:
Outcome prediction after diffuse hypoxic-ischemic brain injury (HIBI), which most commonly occurs after sudden cardiac arrest, remains fraught with uncertainty. Cerebral autoregulation (CA) normally limits fluctuations in cerebral blood flow through pressure induced changes in cerebral arteriolar diameter. CA is disrupted after brain injury, and the degree of autoregulatory failure correlates with the severity of brain injury. CA measurements may thus enable more accurate outcome prediction after HIBI.

Hypothesis:
We hypothesized that the degree of impairment in cerebrovascular pressure reactivity, one of the principle mechanisms of CA, correlates with the extent of HIBI and can predict outcome.

Methods:
Intracranial pressure (ICP) and mean arterial pressure (MAP) were continuously recorded for all subjects. The Pressure Reactivity Index (PRx) was calculated as a moving linear correlation coefficient between ICP and MAP for each 30 sec data epoch. PRx is positive when ICP increases in concert with MAP and implies impaired pressure reactivity. For each subject, both the mean PRx for the entire recording session as well as the proportion of PRx values > 0.2 (previously found to predict poor outcome in TBI) were calculated.

Results:
We included 22 consecutive patients with HIBI who underwent invasive ICP monitoring in this single center observational study between 02/2016-02/2018. Median age was 41 (range 20-77), 36% (8/22) survived to hospital discharge, and 18% (4/22) had return of consciousness. The median time of ICP monitoring was 101 hr (range 8-381 hr). HIBI was due to cardiac arrest in 19/22 patients and prolonged hypoxia in 3/22. Mean PRx was significantly higher in patients without return of consciousness (0.49 ± 0.05 vs. 0.036 ± 0.032, p = 0.001), as was the proportion of PRx values > 0.2 (0.73 ± 0.037 vs 0.34 ± 0.058, p < 0.001). All patients with return of consciousness had mean PRx < 0.2. Using this cutoff value, PRx had a 94% sensitivity and 100% specificity for predicting death or vegetative state.

Conclusions:
Continuous pressure reactivity measurements correlate with outcome after HIBI, and may be a useful adjunct for neuroprognostication. Future studies are needed to validate these findings in larger cohorts.
Abstract 129: Effect of Defibrillation Dose and Waveform Characteristics on Defibrillation Success in Pediatric In-Hospital Cardiac Arrest
Authors: Raymond Tia T , Duval-Arnould Jordan , Quan Weilun , Chai Sam , Ryerson Lyndsay , Lasa Javier , Meaney Peter , Berg Robert , Nadkarni Vinay , Niles Dana , Silver Annemarie , de Caen Allan , Atkins Dianne
Published: July 2021

Introduction:
Amplitude spectral area (AMSA) predicts successful defibrillation (DF) and return of spontaneous circulation (ROSC) in adults but has not been studied during pediatric in-hospital cardiac arrest (IHCA).

Hypothesis:
We characterized DF dose and AMSA during pediatric IHCA from a pediatric resuscitation quality (pediRES-Q) collaborative and hypothesized that a threshold value of AMSA could predict successful DF.

Methods:
Children <18 years with witnessed IHCA, ventricular fibrillation (VF) as the initial rhythm, and those who had complete CPR quality metric data captured from the bedside defibrillator (ZOLL R-Series, Chelmsford, MA) were studied. Energy dose, initial AMSA (
i
AMSA) and pre-shock AMSA (
p
AMSA) [2.5-sec ECG window before defibrillation] for predicting DF success were calculated, together with receiver operator (ROC) curves. Successful DF (sDF) was defined as return of an organized rhythm 5 seconds after DF. Sustained ROSC was defined as >20 minutes without chest compressions. Events with DF due to ventricular tachycardia, inappropriate shocks (i.e. supraventricular tachycardia, conduction block), unavailable AMSA values, and VF events using <1 J/kg for DF were excluded.

Results:
Between 2015-2018, 34 subjects (median age 7.4 years [1.3,13.1]; median weight 19.4 kgs [8.9, 41.7]) with IHCA due to VF were enrolled. We analyzed 26 shocks in 18 children < 8 years and 25 shocks in 16 children 8 to <18 years. For children < 8 years, the initial DF median dose/kg was 2.5 [2.3,3.3] J/kg with sDF in 14/26 (54%) shocks and sustained ROSC in 10/18 (56%) children. For those 8 to <18 years, initial DF median dose/kg was 3.0 [2.5,3.4] J/kg with sDF in 10/25 (40%) shocks and sustained ROSC in 10/16 (63%). AMSA was significantly higher prior to sDF than in unsuccessful DF (
p
AMSA 19.14±8.11 vs.12.0±7.38 mV-Hz, p = 0.0021;
i
AMSA 19.08±7.38 vs. 11.04±6.57 mV-Hz, p = 0.0053). Area under the ROC curve was 0.765 for
p
AMSA and 0.796 for
i
AMSA.

Conclusions:
We characterized DF dose and AMSA during pediatric IHCA with an initial rhythm of VF and found that sDF was significantly associated with AMSA >19 mV-Hz. Future studies should determine the AMSA threshold that predicts sDF in children due to differences in heart size and cardiac arrest etiology.
Abstract 151: Do the Simplified 2015 ERC Guidelines Improve Basic Life Support Performance Compared to 2010 ERC Guidelines?
Authors: Nguyen Dung T , Lauridsen Kasper G , Johnsen Josephine , Bomholt Katrine B , Løfgren Bo
Published: July 2021

Background:
The European Resuscitation Council (ERC) 2015 basic life support (BLS) algorithm has been simplified compared with the ERC 2010 BLS algorithm. Simplification of resuscitation guidelines may facilitate learning and improve guidelines adherence. This study aimed to study BLS performance using ERC 2015 compared with ERC 2010 guidelines.

Methods:
This is an observational study including video recordings of laypersons being skill tested after participation in a standardized ERC BLS/AED course using either the simplified ERC 2015 or ERC 2010 guidelines. The endpoints were 1) performing all steps of the BLS/AED algorithm correctly, 2) remembering the sequence of actions of the BLS/AED algorithm, 3) time to emergency medical service call, 4) time to first chest compression and 5) time to first shock.

Results:
We analyzed videos of 100 laypersons (50 trained using the simplified 2015 guidelines and 50 trained using the 2010 guidelines). Overall, 78% and 62% correctly performed all of the steps of the 2015 and 2010 guidelines respectively (p=0.08), whereas 94% and 82% remembered the correct sequence of actions of the 2015 and 2010 algorithms, respectively (p=0.06). There was no significant difference between participants following the 2015 vs 2010 algorithms with respect to time to emergency medical service call (difference: 0 sec, (95% confidence interval (CI): -3; 2) P=0.70), time to first chest compression (difference: 0 sec, (95% CI: -3;3) P=1.00), and time to first shock (difference: 0 sec, (95% CI: -6; 7) P=0.90).

Conclusion:
Laypersons tends to better perform resuscitation and adhere to the BLS algorithm when using the simplified ERC 2015 guidelines compared to the 2010 Guidelines. There were however no differences in time to emergency medical service call, time to first chest compression and shock delivery.
Abstract 167: Assessing Laryngoscope Blade Positioning During Pediatric Intubation by Video Review
Authors: Kharayat Priyanka , Donoghue Aaron , Nishisaki Akira , Laverriere Elizabeth
Published: July 2021

Introduction:
Classical teaching in laryngoscopy advocates the use of Miller (Straight) blades to be placed underneath the epiglottis and lift it, whereas for Macintosh (Curved) blades the tip is positioned in the vallecula. Published studies in anesthesia suggest that straight blade positioning in the vallecula may be a satisfactory technique for small children. However, there is no clear evidence of consistent implementation of this methodology in practice and associated intubation success.

Objectives:
To assess laryngoscope blade tip position during pediatric tracheal intubation in the emergency department (ED) and its association with intubation success and time of laryngoscopy.

Methods:
Single center retrospective observational cohort study. Children undergoing tracheal intubation in a tertiary pediatric ED under video-recorded conditions were eligible for inclusion. A CMAC video laryngoscope was used as first line device with the video feed recorded for review. Videos were reviewed and the blade tip position during intubation recorded by study personnel. Blade tip position was categorized as ‘Correct’ if the curved blade was in the vallecula or straight blade was lifting the epiglottis; otherwise the position was categorized as ‘Incorrect’. Time of laryngoscopy was defined as time from blade insertion to removal. Univariate analysis between covariates was done by Fisher’s exact testing for intubation success and by nonparametric methods for laryngoscopy time.

Results:
A total of 17 complete videos were included in the study. Mac blade was used correctly in 8/10 cases (80%); Miller was used correctly in 1/7 cases (14%). Among infants (≤ 12 months), the Miller was used incorrectly in 3/4 cases (75%). Intubation was successful in 9/9 cases (100%) with correct blade position and in 5/8 cases (63%) with incorrect position (p=0.04). There was no significant difference in mean calculated laryngoscopy time for correct versus incorrect blade tip position (37.90 ± 26.80 sec vs. 44.33± 15.22 sec, p=0.12)

Conclusion:
Correct position of the laryngoscope blade tip is associated with higher intubation success. There was no significant difference in the laryngoscopy time for both correct and incorrect blade position.
Abstract 17: Controlled Progressive Elevation Maximizes Cerebral Perfusion Pressure During Head up CPR in a Swine Model of Cardiac Arrest
Authors: Moore Johanna C , Salverda Bayert , Lick Michael , Rojas-Salvador Carolina , Debaty Guillaume , Segal Nicolas , Lurie Keith G
Published: July 2021

Background:
Elevation of the head and thorax (HUP) during cardiopulmonary resuscitation (CPR) has been shown to result in a doubling of brain blood flow with higher Cerebral Perfusion Pressures (CerPP) after prolonged active compression-decompression (ACD) CPR with an impedance threshold device (ITD). However, the optimal angle and speed of elevation are unknown.

Methods:
In study A, in an anesthetized female 40 kg pig model of untreated ventricular fibrillation for 8 min, different HUP angles were assessed (20°, 30°, 40°) in a randomized manner each over a 5-minute periods of ACD+ITD CPR. Based upon study A results, study B was performed, wherein animals were randomized to the two following sequences: 20°, 30°, 40° or 40°, 30°, 20° using the same protocol. The primary endpoint was mean ± SD CerPP (mmHg) for both studies.

Results:
In study A, 18 pigs were studied. Overall, there was no optimal HUP angle: CerPP was 36 ± 19 for 20°, 42 ± 21 for 30°, and 44 ± 27 for 40° (p = 0.57). However, CerPPs were higher if 40
o
HUP was performed during the last 5 minutes of the resuscitation (77 ± 17), versus 20
o
HUP and 30
o
HUP (44± 18, p = 0.003), suggestive of a sequence effect. To test this hypothesis, study B then enrolled additional animals to compare two elevation sequences 20°, 30°, 40° (n = 6) or 40°, 30°, 20° (n = 5). At 15 min of CPR, the CerPP for 20°, 30°, 40° group was 60 ± 17 and for 40°, 30°, 20° the CerPP was 23 ± 19 (p = 0.01). CerPPs were higher for the 20°, 30°, 40° group throughout the resuscitation (Figure 1). Coronary perfusion pressure was also significantly higher in the 20°, 30°, 40° group (50 ± 17 mmHg versus 22 ± 16 mmHg, p = 0.036)

Conclusions:
There did not appear to be an optimal HUP angle during ACD+ITD CPR. By contrast, there was an optimal HUP sequence (20,30,40) that resulted in significantly higher CerPP, suggesting controlled progressive elevation is important when performing HUP CPR as compared to an absolute immediate elevation of the head and thorax.
Abstract 171: Developing an ECPR Program for Out of Hospital Cardiac Arrest
Authors: Chonde Meshe , Escajeda Jeremiah , Elmer Jonathan , Boujoukos Arthur , Sappington Penny L , Guyette Frank X , Smith Anson J , Schmidhofer Mark , Callaway Clifton , Sciortino Christopher M , Kormos Robert L
Published: July 2021

Introduction:
Extracorporeal cardiopulmonary resuscitation (ECPR) has emerged as a novel treatment for cardiac arrest that is refractory to conventional cardiopulmonary resuscitation (CPR). As part of a quality improvement initiative we sought to develop a program at our institution.

Hypothesis:
ECPR is a feasible and effective alternative means of resuscitation for patients in refractory cardiac arrest.

Methods:
We developed a multidisciplinary ECPR team consisting of staff from Emergency Medical Services (EMS), Emergency Department, Cardiology, Cardiac Surgery and Critical Care Medicine. Patients with an out of hospital cardiac arrest (OHCA) refractory to medical treatment were identified by EMS and brought to our institution if they met our program selection criteria. The patient was cannulated in the Emergency Department or Catheterization Laboratory, then underwent coronary angiogram with intervention if applicable and was transferred to cardiothoracic intensive care unit (ICU) for further care.

Results:
From October 1
st
2015 to March 31
st
2018, a total of 1165 out of hospital cardiac arrests occurred, of which five met criteria for our study. Median age was 47 [IQR 32-53] and four were men. Most common arrest rhythm was VF (80%), one patient had ST elevation on EKG. Time from arrest to initiation of ECMO was 63 [IQR 59-69] min with 5 [IQR 3-6] defibrillations and 6 [IQR 6-7] doses of epinephrine administered. Four patients were successfully cannulated (80%). Cannulation time was 21 [IQR 16-33] min, with one patient achieving ROSC during cannulation. All patients underwent angiography, with two patients receiving coronary intervention (40%). ECMO duration was 48 [IQR 38-68] hours and length of stay was 2 [IQR 2-8] days. All patients had an initial Pittsburgh Cardiac Arrest Category of 4. Two patients (40%) survived to hospital discharge with good neurologic function.

Conclusions:
ECPR is a potentially life-saving alternative treatment to conventional CPR that is feasible in our patient population.
Abstract 18: Analyzing Heart Rhythm During Chest Compressions in Out-of-Hospital Cardiac Arrest Patients Using New Algorithm for Automated External Defibrillators
Authors: de Graaf Corina , Beesems Stefanie G , Stickney Ronald E , Lank Paula , Chapman Fred W , Koster Rudolph W
Published: July 2021

Purpose:
Automated external defibrillators (AED) prompt the rescuer to stop cardiopulmonary resuscitation (CPR) for ECG analysis. Any interruption of CPR has a negative impact on outcome. We prospectively evaluated a new algorithm (cprINSIGHT) which can analyse the ECG while rescuers continue CPR.

Methods:
We analysed data from patients with attempted resuscitation from OHCA who were connected to an AED with cprINSIGHT (Stryker Physio-Control LIFEPAK CR2) between June 2017 and June 2018 in the Amsterdam Resuscitation Study region. The first analysis in the CR2 is a conventional analysis; subsequent analyses use the cprINSIGHT algorithm. This algorithm classifies the rhythm as shockable (S), non-shockable (NS), or no decision. If no decision, the AED prompts for a pause in CPR and uses its conventional algorithm. The characteristics of the first 3 cprINSIGHT analyses (analyses 2-4) were analysed. Ventricular fibrillation (VF) cases were both coarse and fine VF with a lower threshold of 0.08 mV.

Results:
Data from 132 consecutive OHCA cases were analysed. The initial recorded rhythm was VF or pulseless ventricular tachycardia (VT) in 35 cases (27%), pulseless electrical activity in 34 cases (25%) and asystole in 63 cases (48%). In 114 cases (86%), 1 or more cprINSIGHT analyses were done. Analyses 2-4 covered 90% of all cprINSIGHT analyses. The analyzed rhythm was VF/VT in 12-17%, organised QRS rhythm in 29-35% and asystole in 51-56% (see table). cprINSIGHT reached a S or NS decision in 65-74% of cases, with a sensitivity of 90-100% and a specificity of 100%. When it reached no decision, the rhythm was asystole in 65-79% of analyses, VF/VT in 0-9% and QRS rhythm in 18-27%; conventional analysis followed. Chest compression fraction was 85-88%, CPR fraction was 99%.

Conclusion:
This new algorithm analysed the ECG without need for a pause in chest compressions 65-74% of the time and had 90-100% sensitivity and 100% specificity when it made a shock or a no shock decision.
Abstract 188: Investigation of the Mechanism of Action of Hydrogen Gas in Hemorrhagic Shock
Authors: Tamura Tomoyoshi , Sano Motoaki , Matsuoka Tadashi , Hayashida Kei , Homma Koichiro , Kajimura Mayumi , Suzuki Masaru , Fukuda Keiichi , Sasaki Junichi
Published: July 2021

Background:
Molecular hydrogen gas (H
2
) is known to alleviate ischemia-reperfusion injury; however, the mechanism of action involved remains unknown. Metabolome analysis of tissue subjected to ischemia-reperfusion injury has revealed xanthine oxidoreductase (XOR) as a candidate target molecule for H
2.

Purpose:
The effects of H
2
and the XOR inhibitor (XORi) on resuscitation after hemorrhagic shock (HS) were examined.

Methods:
Male Sprague-Dawley rats were subjected to HS by the withdrawal of blood to maintain a mean arterial pressure (MBP) of 35 mmHg for 60 minutes (T0 to T60). They were then resuscitated with lactated Ringer’s solution with 3 times the shed blood volume over 30 minutes (T60 to T90). The animals were randomly assigned into 3 groups: H
2
inhalation (1.3% H
2
) from T30 (n=6), XORi administration (Topiroxostat 10 mg/kg, orally administered at 60 minutes before induction of HS) (n=5), and control (CTL) (n=5). The rats were observed until 2 hours after fluid resuscitation (T210).

Results:
Compared to that in the control group, the lactate level at 60 minutes after introduction of HS was lower in the XORi group, while the MBP after 2 hours of fluid resuscitation was higher in the H
2
group. XOR activity in the plasma, liver, kidney, and lung tissue was suppressed in the XORi group, but not in the H
2
group. Increased permeability of the pulmonary vasculature associated with increased levels of plasma inflammatory cytokines and plasma Syndecan-1 (a marker of endothelial glycocalyx degradation) after 2 hours of fluid resuscitation was ameliorated only in the H
2
group.

Conclusion:
The mechanisms of action possibly differ between H
2
and XORi. XORi confers resistance to ischemia by suppressing anaerobic glycolysis during ischemia. On the other hand, H
2
stabilizes hemodynamics via suppression of inflammation and vascular hyperpermeability after resuscitation.
Abstract 196: Comparing Bystander Response to an Unannounced Cardiac Arrest Based on Victim Gender Using an Immersive Virtual Reality System
Authors: Leary Marion , Almodovar Alfredo , Buckler David , Patel Jaldhi , Chaudhary Zainab A , Karwat Ariel , Abella Benjamin S , Blewer Audrey L
Published: July 2021

Introduction:
Bystander response to a sudden cardiac arrest (SCA) should ideally be the same for all victims, however studies have shown disparities in response exist based on the gender of the victim. Current virtual reality (VR) wearable technology allows for the creation of high realism scenarios permitting manipulation of the victim’s gender in order to observe bystander response.

Objectives:
We sought to compare lay bystander response to an unannounced simulated VR SCA event based on the victim’s gender.

Methods:
Using our VR SCA system integrated with a CPR recording manikin, we randomized the avatar victim’s gender to either female or male (Figure 1). Subjects were able to interact with simulated bystanders, give vocal commands such as “call 911” or “get an AED”, and perform CPR on the simulated victim in the virtual environment while simultaneously performing CPR on the manikin. Subjects were unaware of the nature of the event but were told to respond however they would in real-life to an emergency situation. Subject’s ability to proceed through the Chain of Survival (Call 911, Perform CPR, Ask for and Use an AED) and CPR quality were recorded.

Results:
Between 9/2017 and 12/2017, 75 subjects were enrolled; mean age was 31±11 yrs, 35% were female, 49% were White, and 66% had never been trained in CPR or were trained >2 yrs prior. In total, 59% of subjects performed CPR, and 11% used an AED. CPR was performed on male victims 65% of the time vs 54% on female victims (p=NS, Figure 2a); An AED was used 21% of the time for male victims vs 15% for female victims (p=NS, Figure 2b). If the subject was male, CPR was performed on a female victim 56% of the time vs 71% for a male victim; female subjects performed CPR on a female victim 50% vs 58% on a male victim (p=NS).

Conclusion:
In our unannounced, immersive VR SCA study, there was a trend toward less CPR and AED use on female avatar victims. Future work will need to be powered to evaluate disparities in CPR and AED use based on gender.
Abstract 207: Dissemination of Hands-Only Cardiopulmonary Resuscitation and the Impact on the Outcome in School Students and Young Adults After Out-of-Hospital Cardiac Arrest of Presumed Cardiac Origin: A Japanese Nationwide Utstein Registry Study
Authors: Mitani Yoshihide , Yodoya Noriko , Ohashi Hiroyuki , Sawada Hirofumi , Hirayama Masahiro
Published: July 2021

Introduction:
Out-of-hospital cardiac arrests (OHCA) of presumed cardiac origin witnessed by nonfamily members in the daytime are most effectively resuscitated in the youth, in which the impact of recently disseminated hands-only cardiopulmonary resuscitation (CPR) is poorly understood.

Hypothesis:
Dissemination of hands-only CPR is associated with the better outcome in school students and young adults after such OHCA.

Methods:
We investigated OHCA of presumed cardiac origin in the youth (Group A, 7-12y; group B, 13-18y; group C, 19-22y; group D, 23-35y) which are witnessed by nonfamily members in the daytime (6:00-17:59) during 2005-15 by using Japanese nationwide Utstein registry.

Results:
We recruited 1,646 pts, in which N of pts was 92 (A), 382 (B), 229 (C) and 943 (D); ventricular fibrillation (VF) as the initial rhythm (%) was 48, 70, 64, and 59; bystander’s CPR (%) was 81, 80, 71 and 68; hands-only/bystander’s CPR (%) was 32, 38, 57, 56; bystander’s automated external defibrillator (AED) (%) was 37, 44, 24 and 19; the favorable neurological outcome at 1 month (CPC1-2)(%) was 46, 49, 39 and 30. Compared with group D, %bystander’s CPR (p=.013 in A, <.001 in B), %bystander’s AED (<.001 in both), and %CPC1-2 (.005, <.001) was higher but %hands-only CPR(<.001 in both) was lower in A and B, independent of the calendar year. Compared with 2005-09, %hands-only CPR, %bystander’s AED and CPC1-2 were higher in all age groups (<.005 in all) in 2010-15. In multivariate logistic analysis (gender, age groups (vs D), CPR type (conventional or hands-only CPR vs no CPR), bystander’s AED, the initial VF, emergency response time, calendar year), hands-only CPR (p=.03), bystander’s AED(<.001), female gender(.045), initial VF (<.001), emergency response time (<.001), and calendar year (<.001) were independently associated with CPC1-2.

Conclusions:
The present investigation demonstrates that resuscitation and outcome parameters after OHCA of presumed cardiac origin were persistently better in school students than young adults and that %hands-only CPR, which was persistently lower in school students, was independently associated with the better outcome in the youth overall. This finding may give a clue to further improvement of the outcomes in school students after OHCA.