Atrial Fibrillation Occurring During Acute Hospitalization: A Scientific Statement From the American Heart Association.

Acute atrial fibrillation is defined as atrial fibrillation detected in the setting of acute care or acute illness; atrial fibrillation may be detected or managed for the first time during acute hospitalization for another condition. Atrial fibrillation after cardiothoracic surgery is a distinct type of acute atrial fibrillation. Acute atrial fibrillation is associated with high risk of long-term atrial fibrillation recurrence, warranting clinical attention during acute hospitalization and over long-term follow-up. A framework of substrates and triggers can be useful for evaluating and managing acute atrial fibrillation. Acute management requires a multipronged approach with interdisciplinary care collaboration, tailoring treatments to the patient's underlying substrate and acute condition. Key components of acute management include identification and treatment of triggers, selection and implementation of rate/rhythm control, and management of anticoagulation. Acute rate or rhythm control strategy should be individualized with consideration of the patient's capacity to tolerate rapid rates or atrioventricular dyssynchrony, and the patient's ability to tolerate the risk of the therapeutic strategy. Given the high risks of atrial fibrillation recurrence in patients with acute atrial fibrillation, clinical follow-up and heart rhythm monitoring are warranted. Long-term management is guided by patient substrate, with implications for intensity of heart rhythm monitoring, anticoagulation, and considerations for rhythm management strategies. Overall management of acute atrial fibrillation addresses substrates and triggers. The 3As of acute management are acute triggers, atrial fibrillation rate/rhythm management, and anticoagulation. The 2As and 2Ms of long-term management include monitoring of heart rhythm and modification of lifestyle and risk factors, in addition to considerations for atrial fibrillation rate/rhythm management and anticoagulation. Several gaps in knowledge related to acute atrial fibrillation exist and warrant future research.

Electrocardiographic measures of repolarization heterogeneity are not predictive for Torsades de Pointes among undifferentiated patients with prolonged QTc: A case control study.

INTRODUCTION: Torsades de Pointes (TdP) is a potentially lethal polymorphic ventricular tachydysrhythmia associated with and caused by prolonged myocardial repolarization. However, prediction of TdP is challenging. We sought to determine if electrocardiographic myocardial repolarization heterogeneity is necessary and predictive of TdP. METHODS: We performed a case control study of TdP at a large urban hospital. We identified cases based on a hospital center electrocardiogram (ECG) database search for tracings from 1/2005 to 6/2019 with heart rate corrected QT (QTc) > 500, QRS < 120, and heart rate (HR) < 60, and a subsequent natural language search of electronic health records for the terms: TdP, polymorphic ventricular tachycardia, sudden cardiac death, and relevant variants. Controls were drawn in a 2:1 ratio to cases from a similar pool of ECGs, and matching for QTc, heart rate, sex, and age. We abstracted historical, laboratory, and ECG data using detailed written instructions and an electronic database. We included a second blinded data abstractor to test data abstraction and manual ECG measurement reliability. We used General Electric (GE) QT Guard software for automated repolarization measurements. We compared groups using unpaired statistics. RESULTS: We included 75 cases and 150 controls. The number of current QTc prolonging medications and serum electrolytes were substantially the same between the two groups. We found no significant difference in measures of QT or T wave repolarization heterogeneity. CONCLUSION: Electrocardiographic repolarization heterogeneity is not greater in otherwise unselected patients with QTc prolongation who suffer TdP and does not appear predictive of TdP. However, previous observations suggest specific repolarization characteristics may be useful for defined patient subgroups at risk for TdP.

Increased ventricular ectopy precedes Torsades de Pointes in patients with prolonged QT.

OBJECTIVE: Torsades de Pointes (TdP) is a potentially lethal ventricular tachydysrhythmia. Prolonged heartrate corrected QT interval (QTc) predicts TdP; however, with poor specificity. We performed this study to identify other predictors of TdP among patients with prolonged QTc. METHODS: We performed a retrospective case control study with 2:1 matching at an urban academic hospital. We searched our hospital electrocardiogram (ECG) database for tracings with heartrate ≤ 60, QTc ≥ 500, and QRS < 120, followed by a natural language search for electronic records with "Torsades," "polymorphic VT," or similar to identify TdP cases from 2005 to 19. We identified controls from a similar ECG database search matching for QTc, heartrate, age, and sex. We compared cardiologic and historical factors, medications, laboratory values, and ECG measurements including ectopy using univariate statistics. For those cases with saved telemetry strips that included preceding beats or TdP onset, we compared ectopy and TdP onset characteristics between the ECG and telemetry strips using mixed linear modeling. RESULTS: Seventy-five cases including 50 with telemetry strips and 150 controls were included. Historical, pharmacologic, laboratory, and cardiologic testing results were similar between cases and controls. The proportion of telemetry tracings with premature ventricular contractions (PVC's) preceding TdP was 0.78 compared to 0.16 for case ECG's (difference 0.62(95%CI 0.44-0.75)) and 0.10 for control ECGs (difference 0.68(95%CI 0.56-0.80)). Average telemetry heartrate was 72 and QTc 549 immediately preceding TdP, similar to the ECG values. CONCLUSIONS: Clinical factors don't differentiate patients with long QTc who develop TdP, however, an increase in PVC's in patients with prolonged QTc may usefully predict imminent TdP.

Diagnostic and prognostic test assessment in emergency medicine: likelihood and diagnostic odds ratios.

Emergency physicians use diagnostic and prognostic tests on a daily basis to assess for life-threatening illness and to inform clinical decisions. Current and new tests must be scientifically evaluated for their diagnostic utility. We discuss the evaluation of diagnostic and prognostic tests using the Bayesian likelihood ratio (LR) and logistic regression diagnostic odds ratio (OR) frameworks. These approaches can be applied to a single test in isolation using univariate techniques, or to a group of tests as commonly applied in clinical practice using multivariate methods. We compare and contrast the relative benefits and challenges of the LR and OR approaches, and assess their interchangeability. The concepts of diagnostic multivariate testing also underlie the framework of clinical decision rules which have gained acceptance in emergency medicine. Clinical decision rules can be viewed as a subanalysis within the joint LR framework. Ultimately, a variety of approaches may be acceptable and even complementary to assess a diagnostic test, each with its own merits and limitations.

Synchronized Chest Compressions for Pseudo-PEA: Proof of Concept and a Synching Algorithm.

Objective: The two objectives of this report are: first, to describe a comparison of chest compressions unsynchronized or synchronized to native cardiac activity in a porcine model of hypotension, and second, to develop an algorithm to provide synchronized chest compressions throughout a range of native heart rates likely to be encountered when treating PEA cardiac arrest. Methods: We adapted our previously developed signal-guided CPR system to provide compressions synchronized to native electrical activity in a porcine model of hypotension as a surrogate of PEA arrest. We describe the first comparison of unsynchronized to synchronized compressions in a single animal as a proof-of-concept. We developed an algorithm to provide optimal synchronized chest compressions regardless of intrinsic PEA heart rate while simultaneously maintaining the chest compression rate within a desired range. We tested the algorithm with computer simulations measuring the proportion of intrinsic and compression beats that were synchronized, and the compression rate and its standard deviation, as a function of intrinsic heart rate and heart rate jitter. Results: We demonstrate and compare unsynchronized versus synchronized chest compressions in a single porcine model with an intrinsic rhythm and hypotension. Synchronized, but not unsynchronized, chest compressions were associated with increased blood pressure and coronary perfusion pressure. Our synchronized chest compression algorithm is able to provide synchronized chest compressions to over 90% of intrinsic beats for most heart rates while maintaining an average compression rate between 90 and 140 compressions per minute with relatively low variability. Conclusions: Synchronized chest compression therapy for pulseless electrical rhythms is feasible. A high degree of synchronization can be maintained over a broad range of intrinsic heart rates while maintaining the compression rate within a satisfactory range. Further investigation to assess benefit for treatment of PEA is warranted.

Is myocardial repolarization duration associated with repolarization heterogeneity?

BACKGROUND: Dispersion of repolarization is theorized as one mechanism by which myocardial repolarization prolongation causes lethal torsades de pointes, (TdP). Our primary purpose was to determine whether prolongation of myocardial repolarization as measured by the heart rate-corrected J-to-T peak interval (JTpkc), is associated with repolarization heterogeneity as measured by transmural dispersion, defined as the median duration from the peak to the end of the T wave (TpTe). METHODS: A retrospective cohort study was performed at a single urban tertiary ED from July 2011-September 2012. Inclusion criteria included all consecutive ED patients with ECG based on QTc and QRS intervals. Automated measurements of all intervals were performed. The association of JTpkc with the dependent variable TpTe was assessed after adjustment for QRS and RR interval durations with a multiple linear regression model. A secondary analysis included a similar adjusted assessment of the association of JTpkc with QT dispersion, QTd. Finally, we constructed two multiple regression models to assess the association of clinical causative factors of TdP with TpTe and JTpkc. RESULTS: Eight hundred seventy-four cases were included: 186 with QTc <500 ms, 118 with QTc ≥500 and QRS ≥120 ms, and 570 with QTc ≥500 and QRS <120 ms. The coefficient for association of JTpkc with TpTe was -0.10 (95%CI -0.15 to -0.05), and for JTpkc with QTd was 0.03 (95% CI -0.01 to 0.06). Clinical causative TdP factors were associated more with JTpkc than TpTe. CONCLUSION: Repolarization duration as measured by JTpkc is not positively associated with dispersion of repolarization as measured by TpTe or QTd. Dispersion of repolarization may not be a critical mechanistic link between QTc prolongation and TdP.

Hypokalemia in women and methadone therapy are the strongest non-cardiologic factors associated with QT prolongation in an emergency department setting.

BACKGROUND: Our primary objective was to determine the adjusted quantitative associations of clinical predictors with QT prolongation, a defining cause of Torsades de Pointes (TdP). METHODS: A retrospective cohort study was performed on consecutive emergency department patients identified by ECG acquisition date, and heart rate corrected QT (QTc) and QRS durations. QTc was modeled as a function of clinical predictors with multiple linear regression. RESULTS: 1010 patients were included. The strongest predictors of QTc and their coefficients were: antidysrhythmic (26.1ms, 95% CI 15.6-36.6) and methadone (43.6ms, 95% CI 28.1-59.2) therapies, and genetic long QT syndrome diagnosis (32.6ms, 95% CI -4.7-70.0). The association of QTc with serum potassium was approximated by a two piecewise linear function that differed by sex. For potassium below 3.9mmol/L, QTc increased by 43.0ms (95% CI 26.2-59.7) and 29.5ms (95% CI 19.1-40.0) for every 1mmol/L decrease in potassium in women and men, respectively. TdP occurred in only 4/686 (0.6%) of patients with QTc≥500 and QRS<120, but mortality during the visit including hospitalization was 8.0%. CONCLUSIONS: QTc duration is highly sensitive to hypokalemia, particularly in women. Methadone prolongs QTc remarkably compared to other non-cardiologic medicines. QTc>500 with normal QRS often signifies profound illness and substantial mortality risk, though not necessarily imminent TdP.

Predictors of patients who present to the emergency department with sepsis and progress to septic shock between 4 and 48 hours of emergency department arrival.

OBJECTIVES: Approximately one in every four patients who present to the emergency department with sepsis progresses to septic shock within 72 hours of arrival. In this study, we describe key patient characteristics present within 4 hours of emergency department arrival that are associated with developing septic shock between 4 and 48 hours of emergency department arrival. DESIGN AND SETTING: This study was a retrospective chart review study of all patients hospitalized from the emergency department with two or more systemic inflammatory response syndrome criteria present within 4 hours of emergency department arrival from September 2010 to February 2011 at two large academic institutions. Patients were excluded if they presented with a ST-elevation myocardial infarction, acute stroke, or trauma; had a cardiac arrest prior to arrival; were pregnant; or admitted from the emergency department psychiatric unit or transferred from an outside hospital. We identified patients with within 4 hours of emergency department arrival and identified those with septic shock at 48 hours after emergency department arrival, using a standard set of guidelines. The primary objective was identifying the number of patients who present with sepsis and progress to septic shock between 4 and 48 hours of emergency department arrival. As to the second objective, we used multivariate logistic regression analysis to identify patient factors associated with the progression of sepsis to septic shock for the aforementioned population. MEASUREMENTS AND MAIN RESULTS: A total of 18,100 patients were admitted from the emergency department, of which 3,960 patients had two or more systemic inflammatory response syndrome criteria, and 1,316 patients had sepsis within 4 hours of emergency department arrival. Although 50 patients presented to the emergency department with septic shock within 4 hours of arrival, 111 patients with sepsis (8.4%) progressed to septic shock between 4 and 48 hours of emergency department arrival. Characteristics associated with the progression of septic shock between 4 and 48 hours of emergency department arrival included female gender (odds ratio, 1.59; 95% CI, 1.02-2.47), nonpersistent hypotension (odds ratio, 6.24; 95% CI, 3.58-10.86), bandemia at least 10% (odds ratio, 2.60; 95% CI, 1.50-4.51), lactate at least 4.0 mmol/L (odds ratio, 5.30; 95% CI, 2.59-10.84), and past medical of coronary artery disease (odds ratio, 2.01; 95% 1.26-3.44). CONCLUSION: Approximately 12% of septic emergency department patients develop shock within 48 hours of presentation, and more than half of these patients develop shock after the first 4 hours of emergency department arrival. Over a third of patients who have sepsis within 4 hours of emergency department arrival and develop septic shock between 4 and 48 hours of emergency department arrival are not admitted to an ICU.

Tachydysrhythmia treatment and adverse events in patients with wolff-Parkinson-white syndrome.

BACKGROUND: Current guidelines recommend avoiding atrioventricular-nodal blocking agents (AVNB) when treating tachydysrhythmias in Wolff-Parkinson-White syndrome (WPW) patients. STUDY OBJECTIVES: We investigated medications selected and resulting outcomes for patients with tachydysrhythmias and WPW. METHODS: In this single-center retrospective cohort study, we searched a hospital-wide database for the following inclusion criteria: WPW, tachycardia, and intravenous antidysrhythmics. The composite outcome of adverse events was acceleration of tachycardia, new hypotension, new malignant dysrhythmia, and cardioversion. The difference in binomial proportions of patients meeting the composite outcome after AVNB or non-AVNB (NAVNB) treatment was calculated after dividing the groups by QRS duration. A random-effects mixed linear analysis was performed to analyze the vital sign response. RESULTS: The initial database search yielded 1158 patient visits, with 60 meeting inclusion criteria. Patients' median age was 52.5 years; 53% were male, 43% presented in wide complex tachycardia (WCT), with 75% in atrial fibrillation (AF) or flutter. AVNBs were administered in 42 (70%) patient visits. For those patients with WCT in AF, the difference in proportions of patients meeting the composite outcome after AVNBs vs. NAVNBs treatment was an increase of 3% (95% confidence interval [CI] -39%-49%), and for those with narrow complex AF it was a decrease of 13% (95% CI -37%-81%). No instances of malignant dysrhythmia occurred. Mixed linear analysis showed no statistically significant effects on heart rate, though suggested a trend toward increasing heart rate after AVNB in wide complex AF. CONCLUSION: In this sample of WPW-associated tachydysrhythmia patients, many were treated with AVNBs. The composite outcome was similarly met after use of either AVNB or NAVNB, and no malignant dysrhythmias were observed.

Bedside ultrasound maximizes patient satisfaction.

BACKGROUND: Bedside ultrasound (US) is associated with improved patient satisfaction, perhaps as a consequence of improved time to diagnosis and decreased length of stay (LOS). OBJECTIVES: Our study aimed to quantify the association between beside US and patient satisfaction and to assess patient attitudes toward US and perception of their interaction with the clinician performing the examination. METHODS: We enrolled a convenience sample of adult patients who received a bedside US. The control group had similar LOS and presenting complaints but did not have a bedside US. Both groups answered survey questions during their emergency department (ED) visit and again by telephone 1 week later. The questionnaire assessed patient perceptions and satisfaction on a 5-point Likert scale. RESULTS: Seventy patients were enrolled over 10 months. The intervention group had significantly higher scores on overall ED satisfaction (4.69 vs. 4.23; mean difference 0.46; 95% confidence interval [CI] 0.17-0.75), diagnostic testing (4.54 vs. 4.09; mean difference 0.46; 95% CI 0.16-0.76), and skills/abilities of the emergency physician (4.77 vs. 4.14; mean difference 0.63; 95% CI 0.29-0.96). A trend to higher scores for the intervention group persisted on follow-up survey. CONCLUSIONS: Patients who had a bedside US had statistically significant higher satisfaction scores with overall ED care, diagnostic testing, and with their perception of the emergency physician. Bedside US has the potential not only to expedite care and diagnosis, but also to maximize satisfaction scores and improve the patient-physician relationship, which has increasing relevance to health care organizations and hospitals that rely on satisfaction surveys.

Diagnostic testing and the average absolute likelihood ratio: application to diagnosing wide QRS complex tachycardia and other ED diseases.

The Bayesian approach to disease diagnosis in the emergency department is facilitated by the use of likelihood ratios (LRs) to evaluate diagnostic tests. The use of dichotomous, interval, and joint LRs for single and multiple tests is reviewed, and comparison is made to regression modeling. The clinical motivation for a single statistic to describe the average change in the odds of disease associated with the use of a particular test or series of tests is described. This new extension of the LR concept is termed the average absolute LR (AALR). Illustrative examples include the use of elevated electrocardiogram ST segment and troponin to diagnose acute myocardial infarction, and serum D-dimer and computed tomographic angiography to diagnose pulmonary embolism. Finally, a detailed example with original data demonstrating the use of the AALR to compare QRS duration, QRS axis, and the 2 tests combined to diagnose ventricular tachycardia in patients with stable sustained regular wide QRS tachycardia is provided. Application of both tests together to patients with wide QRS complex tachycardia changes the odds of ventricular tachycardia, on average, by a factor of 3.5 (95% confidence interval, 2.4-6.2). Challenges are described, and methods are provided to estimate the 95% confidence interval of the LR and AALR using bootstrapping techniques. The AALR is a test statistic that may be helpful for clinicians and researchers in evaluating and comparing diagnostic testing approaches.

Carotid Ultrasound in Assessing Fluid Responsiveness in Patients with Hypotension and Suspected Sepsis.

PURPOSE: We sought to assess whether ultrasound (US) measurements of carotid flow time (CFTc) and carotid blood flow (CBF) predict fluid responsiveness in patients with suspected sepsis. METHODS: This was a prospective observational study of hypotensive (systolic blood pressure < 90) patients "at risk" for sepsis receiving intravenous fluids (IVF) in the emergency department. US measurements of CFTc and CBF were performed at time zero and upon completion of IVF. All US measurements were repeated after a passive leg raise (PLR) maneuver. Fluid responsiveness was defined as normalization of blood pressure without persistent hypotension or need for vasopressors. RESULTS: A convenience sample of 69 patients was enrolled. The mean age was 65; 49% were female. Fluid responders comprised 52% of the cohort. CFTc values increased significantly with both PLR (P = 0.047) and IVF administration (P = 0.003), but CBF values did not (P = 0.924 and P = 0.064 respectively). Neither absolute CFTc or CBF measures, nor changes in these values with PLR or IVF bolus, predicted fluid responsiveness, mortality, or the need for intensive care unit admission. CONCLUSION: In patients with suspected sepsis, a fluid challenge resulted in a significant change in CFTc, but not CBF. Neither absolute measurement nor delta measurements with fluid challenge predicted clinical outcomes.

Confidence at 100%: Characteristics of Likelihood Ratio Confidence Intervals in the Emergency Medicine Diagnostics Literature.

OBJECTIVE: We hypothesized that "perfect" 100% sample sensitivity or specificity (PSSS) is common in the emergency medicine (EM) literature. When results yield PSSS, calculating the likelihood ratio (LR) 95% confidence interval (CI) has been challenging. Consequently, we also hypothesized that studies with PSSS would be less likely to report the LR and associated CI, and those that did would use imperfect methods. METHODS: We searched PubMed or Scopus for all articles reporting diagnostic test results in the 20 top EM journals from 2011 to 2016 and randomly sampled 124 articles. Trained researchers coded the articles as having PSSS or not ("controls"). We separately sampled 100 articles with PSSS and compared them to 100 controls in terms of their reporting of diagnostic tests and associated CIs. RESULTS: Of the 124 articles, 19.4% (95% CI = 13% to 27.6%) feature a diagnostic test with PSSS. The LR is reported significantly less often in PSSS studies versus control studies: 18 of 100 articles (18% [95% CI = 11.3% to 27.2%]) versus 34 of 100 articles (34% [95% CI = 25% to 44.2%]), with an odds ratio (OR) of 0.43 (95% CI = 0.21 to 0.86). The LR 95% CI is also reported less often in PSSS versus control studies: five of 100 articles (5% [95% CI = 1.9% to 11.8%]) versus 27 of 100 articles (27% [95% CI = 18.8% to 37%]), with an OR of 0.11 (95% CI = 0.02 to 0.44). Five articles with perfect sample sensitivity reported their negative LR CI. The bootstrap method resulted in CIs that were 42.7% smaller on average (range = 16.6% to 63.6%). CONCLUSION: This analysis provides systematic evidence of diagnostic test reporting in the EM literature. Sample sensitivity or specificity of 100% is common. LRs and their associated 95% CIs are infrequently reported, particularly for PSSS samples. When the LR CI is reported in this scenario, it is overly wide. Improved reporting and methods can enhance the utility and confidence in diagnostic tests in EM.

Adenosine for wide-complex tachycardia: efficacy and safety.

OBJECTIVES: : To determine whether adenosine is useful and safe as a diagnostic and therapeutic agent for patients with undifferentiated wide QRS complex tachycardia. The etiology of sustained monomorphic wide QRS complex tachycardia is often uncertain acutely. DESIGN: : A retrospective observational study. SETTING: : Treatment associated with emergency visits at nine urban hospitals. PATIENTS: : Consecutive patients treated with adenosine for regular wide QRS complex tachycardia between 1991 and 2006. INTERVENTIONS: : Treatment with adenosine infusion. MEASUREMENTS AND MAIN RESULTS: : Measured outcomes included rhythm response to adenosine, if any, and all adverse effects. A positive response was defined as an observed change in rhythm including temporary atrioventricular conduction block or tachycardia termination. A primary adverse event was defined as emergent electrical or medical therapy instituted in response to an adverse adenosine effect. A rhythm diagnosis was made in each case. The characteristics of adenosine administration as a test for a supraventricular as opposed to ventricular tachycardia were determined, and the adverse event rates were calculated. A total of 197 patients were included: 104 (90%) of 116 (95% confidence interval, 83%-95%) and two (2%) of 81 (95% confidence interval, 0.3%-9%) supraventricular tachycardia and ventricular tachycardia patients demonstrated a response to adenosine, respectively. The odds of supraventricular tachycardia increased by a factor of 36 (95% confidence interval, 9-143) after a positive response to adenosine. The odds of ventricular tachycardia increased by a factor of 9 (95% confidence interval, 6-16) when there was no response to adenosine. The rate of primary adverse events for patients with supraventricular tachycardia and ventricular tachycardia was 0 (0%) of 116 (95% confidence interval, 0%-3%) and 0 (0%) of 81 (95% confidence interval, 0%-4%), respectively. CONCLUSIONS: : Adenosine is useful and safe as a diagnostic and therapeutic agent for patients with regular wide QRS complex tachycardia.

Cardioplegia defibrillation of circulatory and metabolic phase ventricular fibrillation in a swine model.

INTRODUCTION: We previously found potassium cardioplegia followed by rapid calcium reversal (Kplegia) can achieve defibrillation in a swine model of electrical phase of ventricular fibrillation (VF) comparable to standard care. HYPOTHESIS: Exploring 3 possible potassium dose and timing protocols, we hypothesize Kplegia may benefit resuscitation of longer duration untreated VF. METHODS: Three separate blinded randomized placebo-controlled trials were performed with electrically-induced VF untreated for durations of 6, 9, and 12min in a swine model. Experimental groups received infusion of 1 or 2 boluses of intravenous (IV) potassium followed by a single calcium reversal bolus. Potassium was replaced by saline in the control groups. Outcomes included: amplitude spectrum area (AMSA) during VF, resulting rhythms, number of defibrillations, return of spontaneous circulation (ROSC), and hemodynamics for 1h post ROSC. Binomial and interval data outcomes were compared with exact statistics. Serial interval data were assessed with mixed regression models. RESULTS: Twelve, 12, and 8 animals were included at 6, 9, and 12min VF durations for a total of 32. ROSC was achieved in: 4/6 Kplegia and 3/6 control animals in the 6min protocol, (p=1.00), 4/6 Kplegia and 2/6 control animals in the 9min protocol,(p=0.57), and 0/5 Kplegia and 1/3 control animals in the 12min protocol,(p=0.38). Two of 8 Kplegia animals achieved ROSC with chemical defibrillation alone. CONCLUSIONS: The majority of animals achieved ROSC after up to 9min of untreated VF arrest using K plegia protocols. K plegia requires further optimization for both peripheral IV and intraosseous infusion, and to assess for superiority over standard care. Institutional Animal Care and Use Committee protocol #15127224.