bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 282: Inhibition of Inducible Nitric Oxide Synthase Improves Heart Rate Variability During Sepsis
Authors: Kwiatt Michael E , LaChant Joe , Zanotti Sergio , Hollenberg Steven M
Published: April 2024

Background
Nonlinear hemodynamic variables such as blood pressure and heart rate variability are abnormal in sepsis. Nitric oxide has a complex role in hemodynamic alterations in sepsis. The role of inducible nitric oxide synthase (iNOS) on nonlinear hemodynamic parameters is unknown.

Hypothesis
Selective inhibition of iNOS will alter the response of nonlinear hemodynamic parameters in a murine model of sepsis.

Methods
Radio-transmitters were implanted into the aorta of C57/BL6 wild type (n=15) and C57/BL6 NOS 2 (iNOS knockout) (n=8) mice for continuous hemodynamic monitoring. After 72 hours of recovery, baseline heart rate recordings were captured for 24 hours. Sepsis was induced by cecal ligation and puncture and continuous recordings were taken for the next 48 hours. All mice received antibiotics (ceftriaxone and clindamycin) and fluids (35mg/kg 0.9% NaCl) every 6 hours. Volatility was used as a measurement of variability. Heart rate volatility (HRV) and blood pressure volatility (BPV) measurements were compared between groups.

Results
At baseline the iNOS knockout mice had a higher mean systolic blood pressure (135 vs. 126 mmHg, p<0.001) and lower mean heart rate (504 vs. 534, p<0.001) compared to wild type mice. Following induction of sepsis, heart rate and blood pressure were similar between the two groups. During sepsis the iNOS knockout mice had more frequent normal HRV intervals (48.9 vs. 33.3%, p<0.001) but fewer normal BPV intervals (39.7 vs. 62.8%, p<0.001) than the wild type mice. Survival was significantly higher in the iNOS knockout mice compared to wild type mice (75 vs. 26.7%, p= 0.039).

Conclusions
In conclusion, selective inhibition of iNOS was associated with alterations in nonlinear hemodynamics during sepsis. Heart rate variability was improved in iNOS knockouts and correlated with improved survival. Our findings suggest a complex role of iNOS in nonlinear hemodynamics during sepsis. Heart rate variability may provide unique prognostic information in sepsis.
Abstract 290: Sex Disparities in Chest Compression Quality
Authors: Retzer Elizabeth , Yuen Trevor C , Cua Jefferson L , Edelson Dana P
Published: April 2024

BACKGROUND:
Multiple studies have documented improved outcomes from cardiac arrest for women compared to men, but the etiology of this disparity is unknown. Prior out-of-hospital work has suggested that men have stiffer chests than women, requiring more force to compress the same depth. We hypothesized that this would result in women receiving deeper chest compressions during CPR.

METHODS:
We conducted a prospective study of consecutive, adult, index in-hospital cardiac arrests within a single academic institution between April 2006 and March 2011. CPR quality measures were recorded using a CPR-recording defibrillator (MRX/QCPR, Philips Healthcare). Force data were available for only a subset (n=69). Paired t-tests and chi-squared analyses were used to compare patient demographics, CPR quality parameters and outcomes by sex.

RESULTS:
A total of 503 patients were included in the analysis, of which 53% were women. Results are shown in the table below. Women received deeper chest compressions (48±8mm vs 46±8mm, p=0.005) with higher duty cycles (0.39±0.03 vs 0.38±0.03, p=0.001) and a trend toward decreased leaning compared to men. This was associated with a trend toward improved return of spontaneous circulation (ROSC) and survival to discharge in women. In the subset for whom force data were available, women required less elastic force to reach 5 cm of compression depth (24.5 ± 5.7 kg vs 30.5 ± 8.8 kg, p<0.001), even after adjusting for body mass index (BMI), age, and arrest location (p=0.004).

CONCLUSION:
Men have stiffer chest and receive shallower chest compressions than their female counterparts. This may be a contributor to the differences in survival noted in prior studies. Rescuers should be aware of the need to push harder for male victims of cardiac arrest.
Abstract 34: Efficacy Assessment of Arterial Pressure-Based Cardiac Output for Out-of-Hospital Cardiac Arrest
Authors: Kajino Kentaro , Kishi Masashi , Kitamura Tetsuhisa , Ebihara Takeshi , Yamashita Kimiko , Fuse Takashi , Nomura Fumihiko , Watase Junichiro , Yamayoshi Shigeru
Published: April 2024

Background:
Although patients with post-cardiac arrest syndrome (PCAS) after out-of-hospital cardiac arrest (OHCA) is under hemodynamically volatile state, their hemodynamics might be associated with patients' outcome. FloTrac/Vigileo® operating system is an easy low-invasive technique that can do continuous monitoring on arterial pressure-based cardiac output (APCO) from the arterial pressure curve and can calculate Stroke Volume Index (APCO/Heart rate/Body Surface Area: ml/m
2
). This device has been already available for evaluating fluid responsibility and continuous cardiac output monitoring during peri- and post-operative periods.

Objective:
We aimed to assess the association between APCO values and patients' outcome after OHCA.

Materials and Methods:
A prospective observational study was conducted in our center. This study analyzed for adult non-traumatic OHCA patients who achieved return of spontaneous circulation (ROSC) and hospitalized at our intensive care unit to receive post-resuscitation cares during the period from January 1 to March 31 in 2011. FloTrac/Vigileo® operating system was attached for all OHCA patients immediately after they got ROSC at emergency room.

Results:
This study registered 22 eligible patients. Of them, 7 cases (32%) were survival to discharge (the survival group). There were no differences in patients' characteristics and cares between the survival group and the non-survival group excluding age (70.0±10.0 vs. 82.3±7.4 years old. P=0.004). However, the mean stroke volume index (ml/m
2
) for 24-hours after attachment of FloTrac/Vigileo® operating system was significantly higher in the survival group than in the non-survival group (37.9±10.2 ml/m
2
vs. 28.2±7.72 ml/m
2
, P<0.023).

Conclusion:
The stroke volume index might be effective to predict outcome from OHCA.
Abstract 40: Optimal Cerebral Oxidation Levels for Brain Protection During Resuscitation in Cases of Refractory Cardiac Arrest
Authors: Ito Noritoshi , Nanto Shinsuke , Nagao Ken , Hatanaka Tetuso , Nishiyama Kei , Doi Yasuji , Kurozumi Yuma , Natsukawa Tomoaki , Morita Masaya , Kawata Atsushi , Tsuruoka Ayumu , Sawano Hirotaka , Shibata Hiroyuki , Yamada Noriaki , Okada Ken-ichiro , Hayashi Yasuyuki , Kai Tatsuro , Hayashi Toru
Published: April 2024

Background:
Some clinical studies suggest that exposure to hyperoxia after resuscitation from cardiac arrest might worsen anoxic brain injury.

Objective:
The aim of this study was to investigate the association between regional cerebral oxygen saturation (rSO2) levels measured immediately on hospital arrival and neurological outcome at hospital discharge in cardiac arrest on arrival (CAOA) patients after out-of-hospital cardiac arrest (OHCA)

Methods:
This study was a prospective cohort study. Of 418 OHCA patients, 186 consecutive non-traumatic, CAOA patients were prospectively registered from April 2009 to March 2011. The rSO2 levels were measured with sensors placed on either side of their forehead using a near-infrared spectroscopy device (INVOS, Covidien, US) within 3 minutes after hospital arrival. We monitored rSO2 levels at least for more than one minute and used the lower of the 2 measured rSO2 levels for analysis. Clinical staff performed ordinary post-cardiac-arrest interventions (PCAIs) regardless of rSO2 levels. We divided eligible patients into the four groups by 20%-rSO2 level stratum. The primary endpoint was good neurological outcome (Cerebral Performance Category; =<2) at hospital discharge according to the “Utstein-style” guideline and we compared neurological outcome among the groups.

Results:
Among 186 CAOA patients in the PCAIs era, 18 patients (9.7%) had good neurological outcome. However, none in the lowest level group (rSO2=<20%, n=109) had good neurological outcome at hospital discharge. Mortality after CAOA decreased with increasing rSO2 levels. However, rate of good neurological survivors hit a ceiling in the highest rSO2 group (rSO2>60%, n=12).

Conclusion:
This study suggests that one of the main goals of resuscitation might be to maintain rSO2 levels during resuscitation in cases of refractory cardiac arrest, however rSO2 levels might hit a ceiling for brain protection.
Abstract 42: Cardiac Troponin and Extent of Coronary Artery Disease After Resuscitated Sudden Cardiac Arrest
Authors: Radsel Peter , Noc Marko
Published: April 2024

Interpretation of cardiac troponin after resuscitated sudden cardiac arrest is often difficult because increased values may be caused by cardiac arrest, resuscitation procedures and concomitant myocardial infarction due to obstructive coronary disease. In the present study, we related peak cardiac troponin I (TnI), early postresuscitation electrocardiogram (ECG) and coronary anatomy obtained by urgent coronary angiography following reestablishment of spontaneous circulation (ROSC). Postresuscitation electrocardiogram (ECG) revealed STEMI in 183 patients of whom 179 had at least one obstructive lesion. In 66 patients with ECG patterns other than STEMI, 44 had obstructive coronary disease. As shown in table, peak troponin was much greater in STEMI than in no STEMI groups. Within no STEMI group, greater peak TnI was associated with presence of obstructive coronary artery disease. In conclusion, while great majority of patients with STEMI after ROSC have evidence of at least one obstructive lesion, increased levels of troponin in patients without STEMI indicate presence of at least one obstructive lesion and may thereby facilitate decision for coronary angiography if not performed already on admission.
Abstract 50: Use of Impella Ventricular Assist Device in Patients with Severe Coronary Artery Disease Presenting with Cardiac Arrest
Authors: Mukku Venkatakishore , Cai Qiangjun , Gilani Syed , Fujise Ken , Barbagelata Alejandro
Published: April 2024

Background:
Impella is a percutaneously inserted ventricular assist device (VAD). It has been increasingly used in patients with severe heart failure, cardiogenic shock and high risk percutaneous intervention (PCI). However, the use and efficacy of Impella in patients with severe coronary artery disease (CAD) presenting with cardiac arrest has rarely been reported.

Objective:
To report our center experience in using Impella VAD in CAD patients presenting with cardiac arrest.

Case Reports:
From December 2010 to March 2011, three patients with severe CAD presented to our center with cardiac arrest underwent PCI with Impella support (Table 1).

Summary:
We reported 3 cases of severe CAD presenting with cardiac arrest successfully treated with PCI and Impella support. Our experience demonstrated that Impella VAD may play an adjunctive role in obtaining hemodynamic stability in these high risk patients undergoing PCI. One of the patients was supported to LVAD implantation and the other two had excellent neurological and functional recovery. Our reports suggest an important role of Impella in cardiac arrest population. Earlier Impella implantation after cardiac arrest might provide cardiac support and tissue perfusion until recovery or high risk PCI.
Abstract 10466: In Vivo Reprogramming of Murine Cardiac Fibroblasts into Induced Cardiomyocytes
Authors: Qian Li , Huang Yu , Foley Amy , Vedantham Vasanth , Spencer Ian , Conway Simon J , Fu Jidong , Srivastava Deepak
Published: April 2024

Li Qian, 2011 Finalist and Presenting Author
Abstract 13385: Immunoglobulin E Promotes Vascular Wall Cell Inflammatory Molecule Expression, Apoptosis, and Atherogenesis
Authors: Wang Jing , Cheng Xiang , Shi Guo-Ping
Published: April 2024

Jing Wang, 2011 Finalist and Presenting Author
Abstract 13876: Cardiovascular Magnetic Resonance Imaging Elucidates Genotype-Phenotype Relationships in Patients with Hypertrophic Cardiomyopathy
Authors: Heidary Shahriar , Wheeler Matthew T , Bennett Mihoko V , Chung Jaehoon , Pavlovic Aleksandra , Parent Marie-Claude , Dash Rajesh , McConnell Michael V , Ashley Euan A , Yang Phillip C
Published: April 2024

Shahriar Heidary, 2011 Finalist and Presenting Author
Abstract 13139: In Vivo Differentiation of Epigenetically Reprogrammed Mouse and Human Endothelial Progenitor Cells into Cardiomyocytes Enhances Functional and Anatomical Post-Infarct Myocardial Repair
Authors: Thal Melissa A , Krishnamurthy Prasanna , Hoxha Eneda , Lambers Erin , Verma Suresh , Qin Gangjian , Losordo Douglas , Kishore Raj
Published: April 2024

Melissa A Thal, 2011 Finalist and Presenting Author
Abstract 15548: Screening Entire Health System ECG Databases to Identify Patients with Arrhythmogenic Myocardial Substrate at Increased Risk of Death
Authors: Strauss David G , Mewton Nathan , Verrier Richard L , Nearing Bruce , Killian Tony , Marchlinsky Francis E , Tereshchenko Larisa G , Wu Katherine C , Cox Christopher , Spooner Peter M , Lima Joao A
Published: April 2024

David G Strauss, 2011 Finalist and Presenting Author
Initiation of Thrombus Formation: Novel Role for Thiol Isomerases
Authors: Furie Bruce
Published: April 2024

A fundamental component of protein biosynthesis is the intracellular generation or isomerization of disulfide bonds by thiol isomerases. Nature has apparently borrowed, or more accurately, hijacked this enzymatic machinery to regulate the extracellular initiation of thrombus formation in injured blood vessels. Protein disulfide isomerase, a prototypic thiol isomerase, is of critical import during in vivo arterial thrombus formation. This enzyme is secreted by the stimulated endothelium and activated platelets and is captured within the growing thrombus by b3 integrins, specifically aIIbb3 on platelets and avb3 on the endothelium. Inhibition of PDI blocks both platelet thrombus formation by preventing integrin activation and fibrin generation by preventing the expression of tissue factor activity. High throughput screening of chemical libraries has identified a series of flavonoids, including quercetin, isoquercetin and quercetin rutinoside, that are potent low molecular weight inhibitors of PDI in vitro. ERp5, a PDI-like thiol isomerase, is similarly secreted by platelets and plays a role in thrombus formation in vivo. Low molecular weight thiol isomerase inhibitors block platelet thrombus formation and fibrin generation in vivo and offer a novel target for anti-thrombotic therapy. The precise mechanism by which thiol isomerases control thrombus initiation remains to be unraveled.
Improving Cardiac Arrest Outcomes: Fine-tuning or Paradigm Shift?
Authors: Steen Petter Andreas
Published: April 2024

In the 1970-80ies we studied barbiturates, moderately severe hypothermia, free radical scavengers and calcium blockers without impacting outcome after cerebral ischemia. In fact cardiac arrest outcome in general did not improve much until 2005. We underestimated the impact of CPR quality. Long pauses in inadequate depth chest compressions, particularly before, during and after series of defibrillation attempts were documented and found detrimental. We and others have shown that quality can be improved, but as with quality work also outside the health care industry, it requires continuous focus, local champions and continuous feedback both on performance and results. This is true both pre-and in-hospital, both during CPR and in the post-arrest period. The controversy of CPR or defibrillation first is solved, at least for the moment. The place of drugs during CPR is questionable, without solid clinical evidence for improved long term outcome for any drug. Although not universally achieved, significant improvements in cardiac arrest outcome have been reported by some pre- and in-hospital services over the last 5-6 years due to fine-tuning of the treatment process including much focus on the post-arrest period with temperature control/hypothermia and coronary interventions. There are more fine-tuning challenges ahead, and better implementation of known science is required, but what about paradigm shifts? We tend to forget that globally cardiac arrest of non-cardiac origin is a much larger challenge and opportunity that cardiac arrest of cardiac origin, both as potential lives saved, and even more as life-years saved.
The Wise Use of Technology in the Care of Critically Ill Cardiac Patients
Authors: Funk Marjorie
Published: April 2024

Technology permeates every dimension of critical care practice. Although it offers extraordinary benefits to patients and clinicians, technology may also create problems. The wise use of technology in the care of critically ill patients with heart disease is the focus of Marge Funk's research. During the 2011 Katharine A. Lembright Award Lecture she will describe the development of her program of research. She will give examples of studies that examined the safe and appropriate use of technology, its equitable distribution, and the human-machine interface. She will also discuss research related to the use of a particular type of technology – electrocardiographic monitoring – that has been a thread throughout her research career.
Determinants of Cardiovascular Disease in the 21st Century- -Insights from Two Diverse Populations
Authors: Howard Barbara
Published: April 2024

Seminal work by Ancel Keys established the critical role of elevated cholesterol in explaining population differences in rates of CVD. Subsequent work added hypertension and smoking, and major progress has been made in controlling all three. Despite this, world-wide rates of CVD are increasing, and in the US, there are persistent population disparities. We have conducted longitudinal cohort studies in two uniquely-informative populations in order to evaluate the determinants of CVD. The Strong Heart Study is a population based sample of American Indians. Although little CVD was observed in the mid 20
th
century, rates of both CHD and stroke now exceed those in other US populations. Most events are in persons with diabetes; renal impairment is another major risk factor. Both obesity and diabetes lead to CVD risk factors and preclinical disease at young ages. The GOCADAN (Genetics of Coronary Artery Disease in Alaska Natives) and ASP (Alaska-Siberia Project) studies involve populations of Alaska Eskimos. Once thought to have little CVD, they now manifest high rates of CHD, stroke and heart failure. Obesity and diabetes in this population are lower than US averages, especially in men. However rates of smoking and subclinical infection are high and there has been a dramatic change from their unique traditional diet and physical activity patterns. These two groups serve as models for the many populations now experiencing increases in CVD. For those with epidemics of obesity and diabetes, control of the inevitable CVD will require both aggressive management of CVD risk factors and reversing the trends in obesity and diabetes. In other populations, perhaps in less developed areas, control of CVD may depend on aggressive smoking cessation and on efforts to facilitate lifestyle transitions.
HDL and ABC Transporters Reduce the Proliferation of Hematopoietic Stem and Progenitor Cells, with Anti-atherogenic Consequences
Authors: Tall Alan R.
Published: April 2024

Leukocytosis is a risk factor for athero-thrombotic disease in humans, and develops in animal models of atherosclerosis in response to feeding high fat, high cholesterol diets. The ATP binding cassette transporters ABCA1 and ABCG1 promote cholesterol efflux to apoA-1 and HDL, respectively and are targets of LXR transcription factors. Mice lacking ABCA1/G1 develop a dramatic myeloproliferative phenotype with monocytosis and neutrophilia, associated with expansion and proliferation of hematopoietic stem and myeloid progenitor populations (HSPCs). The transporters are highly expressed in HSPCs where they act to control proliferative responses to growth factors (IL-3, GM-CSF) by regulating plasma membrane lipid rafts and cell surface expression of the common beta subunit of the IL-3/GM-CSF receptor. In Western type diet fed Apoe-/- mice, monocytosis and neutrophilia also develop in association with proliferation and expansion of hematopoietic stem, multipotential progenitor and myeloid progenitor cell populations in the bone marrow and spleen. Apoe is highly expressed in long term hematopoietic stem cells and to a lesser extent in progenitor populations, and acts in a cell autonomous fashion to control myeloid proliferation, monocytosis and accumulation of monocytes in atherosclerotic lesions. Treatment of Apoe-/- mice with infusions of reconstituted HDL and/or LXR activator resulted in normalization of HSPC proliferation, monocytosis and neutrophilia. Together, the findings suggest that ApoE acts in concert with the ATP binding cassette transporters ABCA1 and ABCG1 to control HSPC and myeloid proliferation, monocytosis and atherogenesis. LXR activators and rHDL infusions exert anti-atherogenic effects by controlling HSPC and myeloid proliferation.
Abstract 62: Changes in Plasma Asymmetric Dimethylarginine Levels After Resuscitation from Cardiac Arrest in a Rat Model
Authors: Fumagalli Francesca , Li Volti Giovanni , Sorrenti Valeria , Santangelo Rosa , Di Giacomo Claudia , Gullo Antonino , Latini Roberto , Ristagno Giuseppe
Published: April 2024

Introduction.
During reperfusion after ischemic arrest, endothelial dysfunction and inhibition of nitric oxide synthase (NOS) are observed, due to increased oxidative stress, with subsequent decrease in NO bioavailability. This plays important effects in tissue perfusion regulation and function, i.e. postresuscitation myocardial dysfunction. Asymmetric dimethylarginine (ADMA) is an endogenous competitive inhibitor of NOS and thereby modulates NO production. We therefore hypothesized that plasmatic ADMA level would be altered following resuscitation from cardiac arrest.

Methods.
Ventricular fibrillation was induced in 17 rats and was untreated for 6 min. CPR, including mechanical chest compression, ventilation, and epinephrine, was then initiated and continued for additional 6 min prior to defibrillations. Two hrs (n=6), 4 hrs (n=6) and 72 hrs (n=6) following resuscitation, left ventricle ejection fraction (LVEF) was echocardiographically assessed. Animals were then sacrificed, plasma collected and ADMA levels were measured using an enzyme-linked immunosorbent assay method. Additional 5 rats were not subjected to cardiac arrest and served as controls.

Results.
Severe postresuscitation myocardial dysfunction, represented by depressed LVEF, was observed at 2 and 4 hr postresuscitation (p<0.01, Table). However, LVEF recovered 72 hr after resuscitation. Similarly to myocardial dysfunction, plasmatic ADMA significantly decreased following resuscitation, while its level was restored 72 hr later. However, ADMA reductions were significantly evident only 4 hr after resuscitation (p<0.05, Fig) and therefore occurred slower than LVEF impairment.

Conclusions.
Plasmatic ADMA levels were temporary altered following resuscitation, similarly to postresuscitation myocardial dysfunction. Decreases in plasmatic ADMA may reflect adaptative changes aimed to enhance NO release and thereby preservation of myocardium endothelial function.
Abstract 75: Body Weight-Related Adjustments to Chest Compression Depth by EMS Providers During Out-of-Hospital Cardiac Arrest
Authors: Roosa Jason R , Spaite Daniel W , Panchal Ashish R , Stolz Uwe , Vadeboncoeur Tyler F , Silver Annemarie , Kern Karl B , Bobrow Bentley J , Ewy Gordon A ,   SHARE Study Group
Published: April 2024

Background:
The 2010 AHA Guidelines state rescuers should perform chest compressions (CCs) of at least 2 inches in depth for adult cardiac arrest patients. Although the pediatric guidelines recommend adjustment of CC depth based upon anteroposterior chest dimension, there is no such recommendation for adults.

Purpose:
To determine 1) whether prehospital providers intuitively vary CC depth in adults according to patient size and 2) whether implementation of real-time audiovisual CPR feedback (RTAVF) impacts weight/CC depth variation.

Methods:
CC quality data were prospectively collected prior to (9/08-4/10; Pre-feedback) and after (5/10-12/10; Post-feedback) implementation of an RTAVF system (ZOLL Medical, Chelmsford MA) from 3 EMS agencies. The RTAVF includes a visual display of absolute CC depth and gives audio prompts when depth is outside of the Guideline-recommended range. Among 363 cases of adult, non-traumatic out-of-hospital cardiac arrest (OHCA), body weight was estimated by EMS in 249 patients (study group; 66%). CPR quality data were available for all cases via code review software.

Results:
168 Pre-feedback and 81 Post-feedback study group cases (mean 64±16 years, 68% male). Mean estimated body weight was 201 lbs (quartiles 161, 231; range 70-451) and was not different between groups. CC depth increased significantly with RTAVF use (Pre-feedback = 1.77, 95% confidence interval [CI]:1.71-1.83 in.; Post-feedback = 2.10, CI: 2.04-2.15 in.; p<0.001). CC depth did not vary significantly by patient gender or age (p>0.4). Multivariate linear regression (r
2
=0.23, p<0.001 for model) revealed a significant increase in CC depth with estimated weight in both periods (0.07in/50lbs, p<0.001) after controlling for the presence of RTAVF. RTAVF was not an effect-modifier of the relationship between estimated weight and CC depth (p-value for interaction term=0.4).

Conclusion:
Although not specifically recommended in the 2010 AHA Guidelines for adults, rescuers may instinctively and/or intentionally adjust CC depth according to patient size. In this setting, weight/CC depth adjustments occurred both without and with real-time feedback. Follow-up studies are needed to determine the potential effect of size-adjusted CC depth on patient outcome.
Abstract 8: Elevated Intrathoracic Pressure Is Common During Prehospital Ventilation of Patients with Traumatic Brain Injury
Authors: Davis Daniel , Smith Kimberly , Ludington Morgan C , Minokadeh Anush , Dunford James
Published: April 2024

Background:
Inadvertent hyperventilation is associated with poor outcomes from traumatic brain injury (TBI). Hypocapneic cerebral vasoconstriction is well described and causes an immediate and profound decrease in cerebral perfusion. The hemodynamic effects of positive-pressure ventilation (PPV) remain incompletely understood but may be equally important, particularly in the hypovolemic patient with TBI.

Objective:
To apply a previously described mathematical model of perfusion and ventilation to prehospital ventilation data to predict intrathoracic pressure.

Methods:
Ventilation data from 108 TBI patients (76 ground transported, 32 helicopter transported) were used for this analysis. Ventilation rate (VR) and end-tidal carbon dioxide (PetCO2) values were used to estimate tidal volume (VT). The values for VR and estimated VT were then applied to a previously described mathematical model of perfusion and ventilation. This model allows various lung parameters to be defined to create a pressure-volume relationship, then derives mean intrathoracic pressure (MITP) for various VT and VR values. For this analysis, normal lung parameters were assumed. Separate analyses were performed assuming fixed and variable PaCO2-PetCO2 differences. Data regarding VR, PetCO2, estimated VT, and estimated MITP were presented descriptively.

Results:
A total of 10,647 measurements were included from the 108 TBI patients, representing about 13 minutes of ventilation per patient. Mean VR values were higher for ground patients (21.6 breaths/min) than for air patients (19.7 breaths/min). Estimated VT values were similar for ground and air patients (399 mL vs. 392 mL, respectively). Mean PetCO2 values were lower for ground patients (30.6 mmHg) than for air patients (33.8 mmHg). MITP values were higher for ground versus air patients, assuming either fixed (9.0 vs. 8.1 mmHg) and variable (10.9 vs 9.7 mmHg) PaCO2-PetCO2 differences.

Conclusions:
Hyperventilation is common in prehospital TBI patients as reflected by both hypocapnia as well as rapid VR values. MITP values are elevated and would likely result in detrimental hemodynamic effects, particularly in hypovolemic patients.
Abstract 8110: Dobutamine versus Mirlinone for Intensive Hyperdynamic Therapy to Relieve Focal Cerebral Ischemia Caused by Vasospasm after Subarachnoid Hemorrhage
Authors: Mutoh Tatsushi , Kobayashi Shinya , Kazumata Ken , Ishikawa Tatsuya , Suzuki Akifumi
Published: April 2024

Therapeutic hemodynamic augmentation by increasing cardiac output (CO) is a valuable method of elevating cerebral blood flow and oxygenation in the dysautoregulated vascular territories affected by vasospasm after subarachnoid hemorrhage (SAH). We prospectively assessed the effect of hyperdynamic therapy with dobutamine (DOB) or milrinone (MIL) on regional cerebral oxygenation (rSO
2
) for reversing vasospasm-induced cerebral ischemia, using an integrative monitoring incorporated with uncalibrated pulse contour CO analysis and multi-channel near-infrared spectroscopy. One-hundred ten SAH patients diagnosed to have clinical deterioration due to vasospasm were assigned to receive hemodynamic augmentation with DOB or MIL (n=55 per each group). For hyperdynamic therapy, each inotrope was initiated at low dose (DOB: 3 μg/kg/min; MIL 0.15 μg/kg/min) and then increased in each dose increment until resolution of the symptoms unless any adverse effects occur during the therapy, based on our predefined hemodynamic regimen to induce similar dose-related increase in CO. Real-time CO and rSO
2
changes in conjunction with the assessment of neurological improvements were compared. A total of 418 dose increment challenges (DOB, n=192; MIL, n=226) were performed. In spasm-affected territories, decreased and/or fluctuating rSO
2
was detected compared with recordings in other brain region. Patients who exhibited rapid elevation of CO by each challenge had subsequent uptake and stabilization of rSO
2
. The responses (total number and degree of neurological improvements) were more significant in patients treated with DOB than those treated with MIL (
P <
0.05), although tachycardia that may affect stroke volume depression during the DOB therapy was more evident (DOB 27% vs. MIL 9%). Area under the ROC curve to predict rSO
2
elevation or neurological improvement for both drug groups were significant (
P <
0.0001) and the values were significantly greater in DOB than in MIL (
P <
0.05). In conclusion, DOB can provide more effective hemodynamic augmentation in relieving focal cerebral ischemia in patients suffering from vasospasm after SAH. MIL is also effective in the hyperdynamic therapy but may be used as a second line in a patient subgroup where DOB was contraindicated.
Abstract 8115: Circadian Rhythm Pattern of Events in Tako-tsubo Cardiomyopathy
Authors: Sharkey Scott W , Pink Victoria R , Lesser John R , Garberich Ross F , Maron Martin S , Maron Barry J
Published: April 2024

Background.
Tako-tsubo cardiomyopathy (TTC) is an acute reversible cardiac condition, usually triggered by stressful events, with predilection for older women and a distinctive left ventricular contraction profile. Definition of the diurnal hourly pattern of TTC events may contribute to our understanding of the pathogenesis of this complex entity, but is presently unresolved.

Methods.
We prospectively enrolled 186 consecutive TTC patients at the Minneapolis Heart Institute and (for comparison) 2,975 patients with ST-segment myocardial infarction (STEMI) over the same time period. Circadian periodicity was analyzed for hourly occurrence of events throughout the 24-hour day, in 4-hour interval blocks.

Results.
In TTC, the hourly occurrence of events was not uniformly distributed, but showed a distinct and statistically significant afternoon peak between 12:00 pm (noon) and 4:00 pm, comprising 28% of all TTC events, with a nadir at 12 am - 4 am (chi-square = 25.6; p < 0.001), and uninfluenced by age (Figure 1). In contrast, STEMI patients showed a peak occurrence in the early morning hours, 8:00 am to 12:00 noon, comprising 24% of all events (chi-square = 248; p < 0.001), and consistent with prior literature in coronary artery disease. While TTC patients were predominantly female (i.e., 95%), men and women with STEMI showed no difference in circadian pattern.

Conclusions.
Circadian rhythm of TTC events showed a novel peak in the afternoon hours, distinctive from the STEMI pattern. This hourly timing of TCC events is consistent with environmental factors (i.e., stressful life situations) as the trigger for this condition.
Abstract 8129: A Novel Mutation in HERG Leading to an LQTS Overlap Syndrome
Authors: Shah Ravi , Zilinski Jodi , Abtahian Farhad , Das Saumya
Published: April 2024

Background:
Although mutations and corresponding clinical characteristics of subclasses of long QT syndrome (LQTS) have been described, patients may exhibit “overlap syndromes” not corresponding neatly into classic LQTS phenotypes. Here, we report a novel mutation in the HERG potassium channel associated with LQTS.

Case presentation:
A 36-year-old female with a recurrent syncope presented with loss of consciousness. There was no family or personal history of sudden cardiac death or other cardiovascular disease. Her examination was normal, except for marked sinus bradycardia (49/min). Her initial electrocardiogram (Figure A) disclosed a prolonged QTc interval (620 ms). Transthoracic echocardiography was normal. While sleeping, she had an episode of polymorphic VT (Figure B), and after temporizing with isoproterenol, she underwent implantation of a dual-chamber pacemaker-ICD, programmed for atrial pacing at 80/min. On review of her ECG, she had a broad-based T wave without notching, consistent with an LQT1 phenotype. However, her presentation of bradycardia, nocturnal episodes, and QT interval shortening with tachycardia (rate-adaptive QT shortening) suggested LQT3. We discovered a novel nonsense mutation (G208T) in the potassium channel KCNH2 (HERG), the cause of LQT2, leading to a premature stop codon near the N-terminus of KCNH2, with a non-functional gene product and reduced functional potassium channel expression. Pacing with beta-blockade normalized her QT interval by 6 months (Figure C), suggesting compensation for an altered IKr current by the IKs current (responsive to sympathetic stimulation). She has remained arrhythmia-free at 6 months.

Conclusion:
We report the identification of a novel mutation in HERG leading to a LQTS syndrome. Although gene-specific clinical phenotypes are well defined in LQTS, our case identifies an unusual case of an LQTS “overlap syndrome,” with non-classical clinical, electrocardiographic, and genetic data.
Abstract 8134: Differences in Electrocardiographic Findings Between Takotsubo Cardiomyopathy and Reperfused Non-Q-Wave Anterior Acute Myocardial Infarction
Authors: Kosuge Masami , Ebina Toshiaki , Hibi Kiyoshi , Tsukahara Kengo , Iwahashi Noriaki , Endo Mitsuaki , Maejima Nobuhiko , Morita Satoshi , Uchino Kazuaki , Ishikawa Toshiyuki , Umemura Satoshi , Kimura Kazuo
Published: April 2024

Background:
In takotsubo cardiomyopathy (TC), left ventricular dysfunction dramatically improves in a short time, and negative T waves (Neg T) with QT interval prolongation commonly appear, suggesting viable but sympathetically denervated myocardium. However, these findings are often observed in reperfused non-Q-wave anterior acute myocardial infarction (ant AMI).

Methods:
We compared 34 patients with TC and 237 with non-Q-wave ant AMI in whom occlusion followed by TIMI 3 flow of the left anterior descending coronary artery were documented by emergency coronary angiography. All patients were admitted within 6 h after symptom onset. After admission, ECGs with the greatest amplitude of Neg T (mean 2 days later) were analyzed.

Results:
As compared with patients with non-Q-wave ant AMI, those with TC were older (70±11 vs 61±11 years, p<0.01), more likely to be women (85% vs 21%, p<0.01), and had a lower peak creatine kinase level (289±298 vs 1505±921 mU/ml, p<0.01) despite a lower left ventricular ejection fraction on admission (41±10% vs 52±10%, p<0.01). TC was associated with a longer maximal QTc interval (642±93 vs 586±81 ms, p<0.01), a greater amplitude of maximal Neg T (10±4 vs 8±5 mm. p<0.05), and a greater number of leads with Neg T ≥1.0 mm (10±1 vs 6±2, p<0.01). Distribution of Neg T is shown in Figure, using the Cabrera sequence to display limb leads. In TC, Neg T was always observed in leads -aVR and V4-6, whereas Neg T was rare in lead V1. Neg T in lead -aVR (i.e., positive T wave in lead aVR) combined with no Neg T in lead V1 identified TC with 94% sensitivity, 95% specificity, and 94% accuracy, which was the highest diagnostic accuracy.

Conclusions:
As compared with non-Q-wave ant AMI, negative T waves appear more frequently and broadly in TC, suggesting that TC might be associated with more extensive viable but denervated myocardium. The combination of positive T wave in lead aVR and no negative Twave in lead V1 simply but accurately differentiates TC from non-Q-wave ant AMI.
Abstract 8148: Optimal Number of Antitachycardia Pacing Sequences Associated with Successful Termination of Ventricular Tachyarrhythmias in ICD Patients
Authors: Chong Daniel , Malik Amit Kumar , Tan Boon Yew , Liew Reginald , Teo Wee Siong , Ching Chi Keong
Published: April 2024

Introduction:
Antitachycardia pacing (ATP) has been shown to be effective in terminating ventricular tachyarrhythmias painlessly in ICD patients. Similar success rates for various algorithms for ATP (e.g. Ramp vs Burst) have been described. However, the optimal number of ATP sequences that should be programmed to terminate VT without need for an ICD shock has not been widely studied. We aim to determine if the number of ATP sequences programmed correlated with successful termination of ventricular tachyarrhythmias without need for ICD shock.

Methods:
All patients on follow up at National Heart Centre Singapore with available records of any appropriate ICD therapy within a 3 year period were recruited. Clinical characteristics, device programming and all recorded ventricular tachyarrhythmias were analysed.

Results:
375 VT events in 42 patients were analysed. Median age 59.5 years, median 4 years follow up. 54.7% had ICDs implanted for secondary prevention. Mean VT cycle length was 357ms+/-46ms(SD). Majority (91.6%) had ATP (majority 8 pulses at 88% coupling interval) programmed for VT zone tachycardias. Success rate of ATP with a single programmed ATP sequence was 50%, double sequence 67%, three 85%, four or more 67% - differences statistically significant (p=0.02). 3 or more ATP sequences was associated with reduced overall ICD shocks (p=0.04), inclusive of shocks for VF due to VT acceleration (5% of ATP episodes). There was one mortality in a patient programmed with 3 ATP sequences from unrelated metastatic sigmoid carcinoma.

Conclusions:
In our study population, 3 ATP sequences appeared to be optimal in terminating VT with a concomitant reduction in appropriate but unnecessary shocks. Further studies in larger ICD populations are indicated.
Abstract 82: Continuous Automated Analysis During Ongoing Cardiopulmonary Resuscitation Identifies Rhythms that Convert to Pulsatile Rhythms
Authors: Nakagawa Michael , Gehman Stacy
Published: April 2024

Introduction
Current resuscitation guidelines were designed to reduce “no flow” time during a resuscitation attempt. However, shocks delivered within 30 seconds of fibrillation onset show higher rates of conversion to pulsatile rhythms (PR); therefore, shortened chest compression durations may benefit refibrillation (refib) cases. Continuous ECG Rhythm analysis during resuscitation attempts, including during CPR, could guide rescuers to deliver early shocks when appropriate, while continuing CPR otherwise.

Hypothesis
We assessed if a standard AED rhythm analysis algorithm combined with a measurement of myocardial “vigor” could detect shockable rhythms that convert to PR, regardless of ongoing CPR.

Methods
All delivered shocks (n=954) in a previously described annotated database of records from 165 patients (three EMS systems and two hospitals in five countries) were examined for cases that generated PR (n=64, #pts=27) and for cases of refib (n=323, #pts=87). The period between shocks was analyzed with an AED shock/no-shock algorithm combined with a score related to VF slope and amplitude in a single measure of VF vigor. For refib, detection was considered true positive for rhythms that converted to PR after the next shock if identified 15 seconds prior through 30 seconds after the annotation of refib onset, and false positive if more than 15 seconds preceding onset.

Results
Of the 64 shocks that converted to PR, 81% (n=51) followed refib that started after the preceding shock, while only 19% (n=12) were fibrillation cases refractory to the previous shock. Excluding two cases with insufficient data to analyze, 48 refib cases that generated PR, after a subsequent shock, were detected within 30 seconds of onset (98% sensitivity). Eleven patients showed false positive detections (87% specificity).

Conclusions
Automated ECG rhythm analysis can identify onset of refibrillation with high likelihood of PR while avoiding stoppage of CPR for unresponsive rhythms.
Abstract 8208: Scar Border and Transmural Core Defined by Magentic Resonance Imaging Contribute to T wave Alternans in Patients with Cardiomyopathy: Implications for Identifying Arrhythmogenic Substrate
Authors: Suszko Adrian M , Spears Danna A , Wright Graham A , Crean Andrew M , Pinter Arnold , Yan Andrew T , Ivanov Joan , Chauhan Vijay S
Published: April 2024

BACKGROUND
Structural barriers can lead to discordant action potential (AP) alternans in animal studies by slowing conduction and increasing AP gradients. We hypothesized that border zone and midwall scar will promote T wave alternans (TWA) in patients with cardiomyopathy by potentially slowing conduction and uncoupling transmural APs, respectively.

METHODS AND RESULTS
We prospectively studied 40 patients (53±14 yrs, LVEF 40±17%) with ischemic (n=12), dilated (n=12), or hypertrophic cardiomyopathy (n=16). Scar core and border zone were quantified as a percent of LV mass by applying signal-intensity thresholding to late gadolinium enhanced cardiac magnetic resonance images. The transmural distribution of core was determined from the short-axis LV slices and classified as endocardial, epicardial, midwall and full thickness core. TWA was evaluated during incremental atrioventricular pacing at 100, 110 and 120 bpm. TWA was quantified from ECG recordings using the spectral method and classified as positive if Valt >1.9 µV and k >3. +TWA was detected in 27 (68%) patients. The percentages of border zone, epicardial core and midwall core were greater in +TWA vs. - TWA. Maximum TWA magnitude correlated with the relative size of border zone (r=0.52, P<0.001), epicardial core (r=0.54, P<0.001) and midwall core (r=0.40, P=0.01). The heart rate onset for TWA (Valt >0 µV, k >3) was significantly lower in those patients with greater border zone and epicardial core. Multivariate analysis revealed border zone to be the only independent predictor of +TWA (Odds Ratio 1.22/10%, P=0.003).

CONCLUSIONS
In cardiomyopathy patients, scar border zone, epicardial core and midwall core contribute to +TWA. These structural barriers in the presence of +TWA may together provide a potent substrate for lethal ventricular arrhythmias.
Abstract 8229: Layer Specific Strain-Encoded Magnetic Resonance Imaging for Evaluation of Left Ventricular Function and Infarct Transmurality in Patients With Chronic Coronary Artery Disease
Authors: Koos Ralf , Altiok Ertunc , Doetsch Jochen , Marx Nikolaus , Hoffmann Rainer
Published: April 2024

Background:
Strain-encoded imaging (SENC) is a new technique for myocardial deformation analysis in cardiac magnetic resonance imaging (MRI). The study aimed to evaluate whether myocardial deformation imaging performed by SENC allows quantification of regional left ventricular (LV) function and is related to scar transmurality defined by contrast-enhanced MRI (ceMRI).

Methods:
50 patients (age 62 ± 10 years) with chronic ischemic LV dysfunction underwent ceMRI using a clinical 1.5T scanner (Achieva, Philips, Best, The Netherlands). Strain-encoded images were acquired using a commercially available software to calculate myocardial endocardial and epicardial strain (Diagnosoft SENC version 2.05, Diagnosoft Inc., Palo Alto, USA). Layer-specific peak circumferential strain was measured from long-axis views and peak longitudinal strain was evaluated from short-axis views in a 16-segment model. The extent of myocardial infarction was determined semiautomatically (CAAS MRV 3.3, Pie Medical, Netherlands) for each segment as relative amount of hyperenhancement by ceMRI (0%: no infarction; 1-50%: non-transmural infarction; 51-100%: transmural infarction).

Results:
A total of 589 of 600 segments (98%) were analyzed. Endocardial and epicardial circumferential as well as longitudinal strain showed significant differences between visually defined segmental function states and differed also significantly between the degree of infarct transmurality (all p<0.001). A cutoff peak circumferential endocardial strain value of -15% differentiated nontransmural from transmural infarcted myocardium with a sensitivity of 100% and a specificity of 86% (area under the curve (AUC) 0.94). Distinction of nontransmural infarcted myocardium from transmural infarcted myocardium was done more accurately using circumferential endocardial strain compared to longitudinal endocardial strain (AUC 0.94 vs. AUC 0.76, p=0.003).

Conclusions:
Layer-specific SENC provides objective quantification of regional myocardial function and allows accurate discrimination between different transmurality states of myocardial infarction. Circumferential endocardial strain showed the best distinction between the different degrees of infarct transmurality.