High-Energy Pacing Inhibits Slow Wave Dysrhythmias in the Small Intestine

The motility of the gastrointestinal tract is coordinated in part by rhythmic slow waves, and disrupted slow wave patterns are linked to functional motility disorders. At present, there are no treatment strategies that primarily target slow wave activity. This study assessed the use of pacing to suppress glucagon-induced slow wave dysrhythmias in the small intestine. Slow waves in the jejunum were mapped in vivo using a high-resolution surface-contact electrode array in pigs (n=7). Glucagon was intravenously administered to induce hyperglycemia. Slow wave propagation patterns were categorized into antegrade, retrograde, collision, pacemaker and uncoupled activity. Slow wave characteristics such as period, amplitude and speed were also quantified. Post-glucagon infusion, pacing was applied at 4 mA and 8 mA and the resulting slow waves were quantified spatiotemporally. Antegrade propagation was dominant throughout all stages with a prevalence of 55 ± 38% at baseline. However, glucagon infusion resulted in a substantial and significant increase in uncoupled slow waves from 10 ± 8% to 30 ± 12% (p=0.004) without significantly altering the prevalence of other slow wave patterns. Slow wave frequency, amplitude and speed remained unchanged. Pacing, particularly at 8 mA, significantly suppressed dysrhythmic slow wave patterns and achieved more effective spatial entrainment (85%) compared to 4 mA (46%, p=0.039).This study defined the effect of glucagon on jejunal slow waves and identified uncoupling as a key dysrhythmia signature. Pacing effectively entrained rhythmic activity and suppressed dysrhythmias, highlighting the potential of pacing for gastrointestinal disorders associated with slow wave abnormalities.

Unveiling the Multifaceted Problems Associated with Dysrhythmia

Dysrhythmia is a term referring to the occurrence of spontaneous and repetitive changes in potentials with parameters deviating from those considered normal. The term refers to heart anomalies but has a broader meaning. Dysrhythmias may concern the heart, neurological system, digestive system, and sensory organs. Ion currents conducted through ion channels are a universal phenomenon. The occurrence of channel abnormalities will therefore result in disorders with clinical manifestations depending on the affected tissue, but phenomena from other tissues and organs may also manifest themselves. A similar problem concerns the implementation of pharmacotherapy, the mechanism of which is related to the impact on various ion currents. Treatment in this case may cause unfavorable effects on other tissues and organs. Drugs acting through the modulation of ion currents are characterized by relatively low tissue specificity. To assess a therapy's efficacy and safety, the risk of occurrences in other tissues with similar mechanisms of action must be considered. In the present review, the focus is shifted prominently onto a comparison of abnormal electrical activity within different tissues and organs. This review includes an overview of the types of dysrhythmias and the basic techniques of clinical examination of electrophysiological disorders. It also presents a concise overview of the available pharmacotherapy in particular diseases. In addition, the authors review the relevant ion channels and their research technique based on patch clumping.

Excitation-Inhibition Imbalance in Migraine: From Neurotransmitters to Brain Oscillations

Migraine is among the most common and debilitating neurological disorders typically affecting people of working age. It is characterised by a unilateral, pulsating headache often associated with severe pain. Despite the intensive research, there is still little understanding of the pathophysiology of migraine. At the electrophysiological level, altered oscillatory parameters have been reported within the alpha and gamma bands. At the molecular level, altered glutamate and GABA concentrations have been reported. However, there has been little cross-talk between these lines of research. Thus, the relationship between oscillatory activity and neurotransmitter concentrations remains to be empirically traced. Importantly, how these indices link back to altered sensory processing has to be clearly established as yet. Accordingly, pharmacologic treatments have been mostly symptom-based, and yet sometimes proving ineffective in resolving pain or related issues. This review provides an integrative theoretical framework of excitation-inhibition imbalance for the understanding of current evidence and to address outstanding questions concerning the pathophysiology of migraine. We propose the use of computational modelling for the rigorous formulation of testable hypotheses on mechanisms of homeostatic imbalance and for the development of mechanism-based pharmacological treatments and neurostimulation interventions.

Epidemiology, Risk Factors, and Outcome of Cardiac Dysrhythmias in a Noncardiac Intensive Care Unit

Introduction

Several extrinsic factors contribute to the development of cardiac dysrhythmias. In intensive care unit (ICU) settings and among critically ill patients who are exposed to a large number of risk factors, cardiac disturbances are more common.

Objectives

This study aimed to examine the epidemiology, risk factors, and outcome of cardiac dysrhythmias in a non-cardiac ICU.

Methods

This is a retrospective, single-center, observational study conducted in a tertiary noncardiac ICU at Imam Khomeini Hospital in Ahvaz, Iran. Out of the 360 adult patients aged 18 years and older who were admitted to ICU for longer than 24 h, 340 cases who met the study inclusion criteria were recruited between March 2018 until October 2018.

Results

The most common nonsinus dysrhythmias were new-onset atrial fibrillation (NOAF) (12.9%) and ventricular tachycardia (21 patients—6.2%). According to our results, previous percutaneous coronary instrumentation, acute kidney injury, sepsis, and hyperkalemia act as risk factors in the development of cardiac dysrhythmias. Additionally, we found out that thyroid dysfunction and pneumonia can predict the development of NOAF in critically ill patients. The estimated mortality rate among patients with NOAF in this study was 15.7% (p < .05).

Conclusion

Cardiac dysrhythmias are common in ICU patients and treating the risk factors can help to prevent their development and improve patient management and outcome.

Hemodynamic and Rhythmologic Effects of Push-Dose Landiolol in Critical Care-A Retrospective Cross-Sectional Study

BACKGROUND

The highly β1-selective beta-blocker Landiolol is known to facilitate efficient and safe rate control in non-compensatory tachycardia or dysrhythmia when administered continuously. However, efficacy and safety data of the also-available bolus formulation in critically ill patients are scarce.

METHODS

We conducted a retrospective cross-sectional study on a real-life cohort of critical care patients, who had been treated with push-dose Landiolol due to sudden-onset non-compensatory supraventricular tachycardia. Continuous hemodynamic data had been acquired via invasive blood pressure monitoring.

RESULTS

Thirty patients and 49 bolus applications were analyzed. Successful heart rate control was accomplished in 20 (41%) cases, rhythm control was achieved in 13 (27%) episodes, and 16 (33%) applications showed no effect. Overall, the heart rate was significantly lower (145 (130-150) vs. 105 (100-125) bpm, p < 0.001) in a 90 min post-application observational period in all subgroups. The median changes in blood pressure after the bolus application did not reach clinical significance. Compared with the ventilation settings before the bolus application, the respiratory settings including the required FiO2 after the bolus application did not differ significantly. No serious adverse events were seen.

CONCLUSIONS

Push-dose Landiolol was safe and effective in critically ill ICU patients. No clinically relevant impact on blood pressure was noted.

Acupuncture ameliorates Mobile Phone Addiction with sleep disorders and restores salivary metabolites rhythm

OBJECTIVES

Mobile Phone Addiction (MPA) is a novel behavioral addiction resulting in circadian rhythm disorders that severely affect mental and physical health. The purpose of this study is to detect rhythmic salivary metabolites in MPA with sleep disorder (MPASD) subjects and investigate the effects of acupuncture.

METHODS

Six MPASD patients and six healthy controls among the volunteers were enrolled by MPA Tendency Scale (MPATS) and Pittsburgh Sleep Quality Index (PSQI), then the salivary samples of MPASD and healthy controls were collected every 4-h for three consecutive days. Acupuncture was administered for 7 days to MPASD subjects, then saliva samples were collected again. Salivary metabolomes were analyzed with the method of LC-MS.

RESULT

According to our investigation, 70 (57.85%) MPA patients and 56 (46.28%) MPASD patients were identified among 121 volunteers. The symptoms of the 6 MPASD subjects were significantly alleviated after acupuncture intervention. The number of rhythmic saliva metabolites dropped sharply in MPASD subjects and restored after acupuncture. Representative rhythmic saliva metabolites including melatonin, 2'-deoxyuridine, thymidine, thymidine 3',5'-cyclic monophosphate lost rhythm and restored after acupuncture, which may attribute to promising MPASD treatment and diagnosis biomarkers. The rhythmic saliva metabolites of healthy controls were mainly enriched in neuroactive ligand-receptor interaction, whereas polyketide sugar unit biosynthesis was mainly enriched in MPASD patients.

CONCLUSION

This study revealed circadian rhythm characteristics of salivary metabolites in MPASD and that acupuncture could ameliorate MPASD by restoring part of the dysrhythmia salivary metabolites.

Hyperkalemia and Electrocardiogram Manifestations in End-Stage Renal Disease

Hyperkalemia is one of the more common acute life-threatening metabolic emergencies. The aim of our study is to determine the correlation and accuracy of abnormal ECG parameters as a function of serum potassium concentration in the end-stage renal disease (ESRD) population. We performed a retrospective chart review of emergency department patients presenting with ESRD and receiving emergent hemodialysis treatment. A total of 96 patients, each with five independent ED visits, provided 480 sets of ECGs and electrolytes. Of these, four ECGs were excluded for inability to interpret, leaving a total of 476 patient encounters that met all inclusion criteria. Linear regression analysis on the limited data set for serum potassium versus T/R in V2, V3, and V4, PR, and QRS found weak correlations (r2 = 0.02 to 0.12) with statistical significance <0.05 level for T/R in V2, V3, and V4. In summary, we found that a QRS duration of 120 ms or greater is most predictive of hyperkalemia in the ESRD population. On the other hand, T/R ratio, PR interval and QRS duration have poor correlations with serum potassium and are not predictive of hyperkalemia in patients with ESRD.

Localized bioelectrical conduction block from radiofrequency gastric ablation persists after healing: safety and feasibility in a recovery model

Gastric ablation has demonstrated potential to induce conduction blocks and correct abnormal electrical activity (i.e., ectopic slow-wave propagation) in acute, intraoperative in vivo studies. This study aimed to evaluate the safety and feasibility of gastric ablation to modulate slow-wave conduction after 2 wk of healing. Chronic in vivo experiments were performed in weaner pigs (n = 6). Animals were randomly divided into two groups: sham-ablation (n = 3, control group; no power delivery, room temperature, 5 s/point) and radiofrequency (RF) ablation (n = 3; temperature-control mode, 65°C, 5 s/point). In the initial surgery, high-resolution serosal electrical mapping (16 × 16 electrodes; 6 × 6 cm) was performed to define the baseline slow-wave activation profile. Ablation (sham/RF) was then performed in the mid-corpus, in a line around the circumferential axis of the stomach, followed by acute postablation mapping. All animals recovered from the procedure, with no sign of perforation or other complications. Two weeks later, intraoperative high-resolution mapping was repeated. High-resolution mapping showed that ablation successfully induced sustained conduction blocks in all cases in the RF-ablation group at both the acute and 2 wk time points, whereas all sham-controls had no conduction block. Histological and immunohistochemical evaluation showed that after 2 wk of healing, the lesions were in the inflammation and early proliferation phase, and interstitial cells of Cajal (ICC) were depleted and/or deformed within the ablation lesions. This safety and feasibility study demonstrates that gastric ablation can safely and effectively induce a sustained localized conduction block in the stomach without disrupting the surrounding slow-wave conduction capability.NEW & NOTEWORTHY Ablation has recently emerged as a tool for modulating gastric electrical activation and may hold interventional potential for disorders of gastric function. However, previous studies have been limited to the acute intraoperative setting. This study now presents the safety of gastric ablation after postsurgical recovery and healing. Localized electrical conduction blocks created by ablation remained after 2 wk of healing, and no perforation or other complications were observed over the postsurgical period.

Attention: Cardiac contusion

BACKGROUND

The objective of the study is to investigate diagnostic and clinical processes performed for cardiac contusion in patients with blunt thoracic trauma.

METHODS

This study was conducted retrospectively on 65 patients admitted with isolated blunt thoracic trauma to the Emergency Medicine Department. The CT images, the cardiac enzyme levels, the periodic 4-h follow-up electrocardiography (ECGs) in the emer-gency department, and the results of echocardiography, performed at admission and when required according to the clinical status, were investigated. The 1-h and 4-h high-sensitivity troponin I levels were studied, and values above 0.04 ng/ml were considered as positive.

RESULTS

Sixty-five patients with isolated thoracic trauma were included in the study, 23 (35.38%) had pulmonary and cardiac contu-sions both. In 23 (35.38%) patients, pulmonary contusion had been present, and cardiac contusion had not been identified at the initial evaluation. However, during clinical follow-up, troponin became positive, dysrhythmia developed, and the trauma affected the heart in four of these patients. In six (9.24%) patients, cardiac contusion was identified without pulmonary contusion. In 13 (20%) patients, no cardiac or pulmonary contusion was identified. troponin elevation was detected in 10 patients without a diagnosis of cardiac contusion who had a pulmonary contusion, hemothorax, and/or pneumothorax at the time of hospital admission and then with normal troponin levels at 4-h control. We found that there was a statistical agreement between cardiac contusion and troponin-ECG results at 4th h.

CONCLUSION

We advise that all blunt thoracic trauma patients should be screened for cardiac contusion by continuous ECG monitoring and troponin levels.

Targeted ablation of gastric pacemaker sites to modulate patterns of bioelectrical slow wave activation and propagation in an anesthetized pig model

Gastric motility is coordinated by underlying bioelectrical slow waves. Gastric dysrhythmias occur in gastrointestinal (GI) motility disorders, but there are no validated methods for eliminating dysrhythmias. We hypothesized that targeted ablation could eliminate pacemaker sites in the stomach, including dysrhythmic ectopic pacemaker sites. In vivo high-resolution serosal electrical mapping (16 × 16 electrodes; 6 × 6 cm) was applied to localize normal and ectopic gastric pacemaker sites in 13 anesthetized pigs. Radiofrequency ablation was performed in a square formation surrounding the pacemaker site. Postablation high-resolution mapping revealed that ablation successfully induced localized conduction blocks after 18 min (SD 5). Normal gastric pacemaker sites were eliminated by ablation (n = 6), resulting in the emergence of a new pacemaker site immediately distal to the original site in all cases. Ectopic pacemaker sites were similarly eliminated by ablation in all cases (n = 7), and the surrounding mapped area was then entrained by normal antegrade activity in five of those cases. Histological analysis showed that ablation lesions extended through the entire depth of the muscle layer. Immunohistochemical staining confirmed localized interruption of the interstitial cell of Cajal (ICC) network through the ablation lesions. This study demonstrates that targeted gastric ablation can effectively modulate gastric electrical activation, including eliminating ectopic sites of slow wave activation underlying gastric dysrhythmias, without disrupting surrounding conduction capability or tissue structure. Gastric ablation presents a powerful new research tool for modulating gastric electrical activation and may likely hold therapeutic potential for disorders of gastric function.NEW & NOTEWORTHY This study presents gastric ablation as a novel tool for modulating gastric bioelectrical activation, including eliminating the normal gastric pacemaker site as well as abnormal ectopic pacemaker sites underlying gastric dysrhythmias. Targeted application of radiofrequency ablation was able to eliminate these pacemaker sites without disrupting surrounding conduction capability or tissue structure. Gastric ablation presents a powerful new research tool for modulating gastric electrical activation and may likely hold therapeutic potential for disorders of gastric function.

Cardiac responses in paediatric Pompe disease in the ADVANCE patient cohort

Pompe disease results from lysosomal acid α-glucosidase deficiency, which leads to cardiomyopathy in all infantile-onset and occasional late-onset patients. Cardiac assessment is important for its diagnosis and management. This article presents unpublished cardiac findings, concomitant medications, and cardiac efficacy and safety outcomes from the ADVANCE study; trajectories of patients with abnormal left ventricular mass z score at enrolment; and post hoc analyses of on-treatment left ventricular mass and systolic blood pressure z scores by disease phenotype, GAA genotype, and "fraction of life" (defined as the fraction of life on pre-study 160 L production-scale alglucosidase alfa). ADVANCE evaluated 52 weeks' treatment with 4000 L production-scale alglucosidase alfa in ≥1-year-old United States of America patients with Pompe disease previously receiving 160 L production-scale alglucosidase alfa. M-mode echocardiography and 12-lead electrocardiography were performed at enrolment and Week 52. Sixty-seven patients had complete left ventricular mass z scores, decreasing at Week 52 (infantile-onset patients, change -0.8 ± 1.83; 95% confidence interval -1.3 to -0.2; all patients, change -0.5 ± 1.71; 95% confidence interval -1.0 to -0.1). Patients with "fraction of life" <0.79 had left ventricular mass z score decreasing (enrolment: +0.1 ± 3.0; Week 52: -1.1 ± 2.0); those with "fraction of life" ≥0.79 remained stable (enrolment: -0.9 ± 1.5; Week 52: -0.9 ± 1.4). Systolic blood pressure z scores were stable from enrolment to Week 52, and no cohort developed systemic hypertension. Eight patients had Wolff-Parkinson-White syndrome. Cardiac hypertrophy and dysrhythmia in ADVANCE patients at or before enrolment were typical of Pompe disease. Four-thousand L alglucosidase alfa therapy maintained fractional shortening, left ventricular posterior and septal end-diastolic thicknesses, and improved left ventricular mass z score.Trial registry: ClinicalTrials.gov Identifier: NCT01526785 https://clinicaltrials.gov/ct2/show/NCT01526785.Social Media Statement: Post hoc analyses of the ADVANCE study cohort of 113 children support ongoing cardiac monitoring and concomitant management of children with Pompe disease on long-term alglucosidase alfa to functionally improve cardiomyopathy and/or dysrhythmia.

The pathophysiology of uncontrolled hemorrhage in horses

BACKGROUND

Hemorrhagic shock in horses may be classified in several ways. Hemorrhage may be considered internal versus external, controlled or uncontrolled, or described based on the severity of hypovolemic shock the patient is experiencing. Regardless of the cause, as the severity of hemorrhage worsens, homeostatic responses are stimulated to ameliorate the systemic and local effects of an oxygen debt. In mild to moderate cases of hemorrhage (<15% blood volume loss), physiological adaptations in the patient may not be clinically apparent. As hemorrhage worsens, often in the uncontrolled situation such as a vascular breach internally, the pathophysiological consequences are numerous. The patient mobilizes fluid and reserve blood volume, notably splenic stored and peripherally circulating erythrocytes, to preferentially supply oxygen to sensitive organs such as the brain and heart. When the global and local delivery of oxygen is insufficient to meet the metabolic needs of the tissues, a cascade of cellular, tissue, and organ dysfunction occurs. If left untreated, the patient dies of hemorrhagic anemic shock.

CLINICAL IMPORTANCE

An understanding of the pathophysiological consequences of hemorrhagic shock in horses and their clinical manifestations may help the practitioner understand the severity of blood volume loss, the need for referral, the need for transfusion, and potential outcome. In cases of severe acute uncontrolled hemorrhage, it is essential to recognize the clinical manifestations quickly to best treat the patient, which may include humane euthanasia.

KEY POINTS

Uncontrolled hemorrhage may be defined as the development of a vascular breach and hemorrhage that cannot be controlled by interventional hemostasis methods such as external pressure, tourniquet, or ligation. Causes of uncontrolled hemorrhage in horses may be due to non-surgical trauma, surgical trauma, invasive diagnostic procedures including percutaneous organ biopsy, coagulopathy, hypertension, cardiovascular anomaly, vascular damage, neoplasia such as hemangiosarcoma, toxicity, or idiopathic in nature. When a critical volume of blood is lost, the respondent changes in heart rate, splenic blood mobilization, and microcirculatory control can no longer compensate for decreasing oxygen delivery to the tissues In spite of organ-specific microvascular responses (eg, myogenic responses, local mediator modulation of microvasculature, etc), all organs experience decreases in blood flow during severe hypovolemia Acute, fatal hemorrhagic shock is characterized by progressive metabolic acidosis, coagulopathy, and hypothermia, often termed the "triad of death," followed by circulatory collapse.

Localized gastric distension disrupts slow-wave entrainment leading to temporary ectopic propagation: a high-resolution electrical mapping study

Gastric distension is known to affect normal slow-wave activity and gastric function, but links between slow-wave dysrhythmias and stomach function are poorly understood. Low-resolution mapping is unable to capture complex spatial properties of gastric dysrhythmias, necessitating the use of high-resolution mapping techniques. Characterizing the nature of these dysrhythmias has implications in the understanding of postprandial function and the development of new mapping devices. In this two-phase study, we developed and implemented a protocol for measuring electrophysiological responses to gastric distension in porcine experiments. In vivo, serosal high-resolution electrical mapping (256 electrodes; 36 cm²) was performed in anaesthetized pigs (n = 11), and slow-wave pattern, velocity, frequency, and amplitude were quantified before, during, and after intragastric distension. Phase I experiments (n = 6) focused on developing and refining the distension mapping methods using a surgically inserted intragastric balloon, with a variety of balloon types and distension protocols. Phase II experiments (n = 5) used barostat-controlled 500-mL isovolumetric distensions of an endoscopically introduced intragastric balloon. Dysrhythmias were consistently induced in all five gastric distensions, using refined distension protocols. Dysrhythmias appeared 23 s (SD = 5 s) after the distension and lasted 129 s (SD = 72 s), which consisted of ectopic propagation originating from the greater curvature in the region of distension. In summary, our results suggest that distension disrupts gastric entrainment, inducing temporary ectopic slow-wave propagation. These results may influence the understanding of the postprandial stomach and electrophysiological effects of gastric interventions.NEW & NOTEWORTHY This study presents the discovery of temporary dysrhythmic ectopic pacemakers in the distal stomach caused by localized gastric distension. Distension-induced dysrhythmias are an interesting physiological phenomenon that can inform the design of new interventional and electrophysiological protocols for both research and the clinic. The observation of distension-induced dysrhythmias also contributes to our understanding of stretch-sensitivity in the gut and may play an important role in normal and abnormal postprandial physiology.

Association between exposure to Efavirenz and substrates of dysrhythmia in HIV-infected young adults

Background

Dysrhythmia and sudden cardiac arrest occur more likely in HIV patients than healthy subjects. Thus, we need to examine dysrhythmias adverse effects of medications including Efavirenz as early as possible especially in young subjects.

Hypothesis

Efavirenz might have contributed to increased risk of developing common types of dysrhythmia in young HIV infected patients.

Methods

We performed a retrospective cohort study among 62 patients on Efavirenz and 38 controls. All participants were under 40 years old without cardiovascular disease. Total significant dysrhythmia in 24‐hour ECG monitoring was the primary endpoint determined as the composite of high premature ventricular contraction (PVC) (>500 beats per 24 hours), high premature atrial contraction (PAC) (>500 bp24h), sinus pause, atrioventricular blocks, ventricular tachycardia, prolonged QTc, and low heart rate variability (HRV). Modified composite dysrhythmia consisted of low HRV (SD of normal‐to‐normal [SDNN]), high PVC and prolonged QT.

Results

Mean heart rate, Efavirenz regimen, male gender, and CD4 count predicted total dysrhythmia. Odds ratios were 1.108, 2.90, 4.36, and 0.96, respectively. The incidence of total dysrhythmia, high PVC, high PAC, low HRV(SDNN), and prolonged QTc were 54.8%, 41.85%, 9.71%, 45.2%, and 12.9% in patients on Efavirenz against 42.11%, 31.64%, 0%, 34.2%, and 7.91% in controls, respectively (p‐values: .031, .001, <.0001, .063, and .043 respectively). Modified composite dysrhythmia was also more frequent in Efavirenz group than that of control group (69.42% vs. 52.60%, respectively p = .032).

Conclusions

We found that patients with Efavirenz had higher prevalence of frequent PVC, frequent PAC, total significant dysrhythmia, Low HRV and prolonged QTc than controls.

Gastric ablation as a novel technique for modulating electrical conduction in the in vivo stomach

Gastric motility is coordinated by underlying bioelectrical "slow wave" activity. Slow wave dysrhythmias are associated with motility disorders, including gastroparesis, offering an underexplored potential therapeutic target. Although ablation is widely used to treat cardiac arrhythmias, this approach has not yet been trialed for gastric electrical abnormalities. We hypothesized that ablation can create localized conduction blocks and modulate slow wave activation. Radiofrequency ablation was performed on the porcine serosa in vivo, encompassing a range of parameters (55-85°C, adjacent points forming a line, 5-10 s/point). High-resolution electrical mapping (16 × 16 electrodes; 6 × 6 cm) was applied to define baseline and acute postablation activation patterns. Tissue damage was evaluated by hematoxylin and eosin and c-Kit stains. Results demonstrated that RF ablation successfully induced complete conduction block and a full thickness lesion in the muscle layer at energy doses of 65-75°C for 5-10 s/point. Gastric ablation may hold therapeutic potential for gastric electrical abnormalities in the future.NEW & NOTEWORTHY This study presents gastric ablation as a new method for modulating slow wave activation and propagation in vivo, by creating localized electrical conduction blocks in the stomach, validated by high-resolution electrical mapping and histological tissue analysis. The results define the effective energy dose range for creating conduction blocks, while maintaining the mucosal and submucosal integrity, and demonstrate the electrophysiological effects of ablation. In future, gastric ablation can now be translated toward disrupting dysrhythmic slow wave activation.

Arrhythmia in tumor lysis syndrome and associated in-hospital mortality: A nationwide inpatient analysis

BACKGROUND

Tumor lysis syndrome (TLS) is a life-threatening oncologic emergency associated with fatal complications including arrhythmia. The epidemiology and mortality outcomes of arrhythmia in TLS are scarcely studied in the literature.

METHODS

We used the National Inpatient Sample (NIS) to study the prevalence and outcome of arrhythmia in patients hospitalized with TLS (ICD-9 code 277.88) from 2009 to 2014. Baseline characteristics, burden of arrhythmia, and pertinent outcomes were analyzed. Multivariable regression analysis was performed to identify the impact of underlying malignancy in predicting TLS-related mortality.

RESULTS

A total of 9034 cases of arrhythmia among 37 861 TLS patients were identified. More than half of the arrhythmia cases (67%) were found among white old (>65) males admitted to large bed size and urban teaching hospitals. Arrhythmic cohort showed higher frequency of comorbidities such as fluid-electrolyte disturbances, hypertension, congestive heart failure, renal failure, dyslipidemia, diabetes, pulmonary circulatory disorders, chronic pulmonary disease, coagulopathy, and deficiency anemia. The most common malignancies were leukemia, lymphoma, metastatic tumor, and solid tumor without metastasis. We found significantly higher odds of in-hospital mortality among patients with TLS compared to general inpatient population on unadjusted (OR 9.69, 95% CI: 9.27-10.13, P < .001) and adjusted (OR 4.62, 95% CI: 4.39-4.85) multivariable analyses. Overall in-hospital mortality (32% vs 21.3%), median length of stay (11 days vs 9 days), and hospital charges were higher among arrhythmic than nonarrhythmic patients.

CONCLUSION

With the availability of more advanced cancer therapy in the US, nearly one in four inpatient encounters of TLS had arrhythmia. Arrhythmia in TLS patients was associated with higher odds of mortality and increased resource utilization. Therefore, strategies to improve the supportive care of TLS patients plus timely diagnosis and treatment of arrhythmia are of utmost importance in reducing mortality and health-care cost.

Utility of Hypertonic Saline and Diazepam in COVID-19-Related Hydroxychloroquine Toxicity

Background

Hydroxychloroquine (HCQ) poisoning is a life-threatening but treatable toxic ingestion. The scale of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection (COVID-19) and the controversial suggestion that HCQ is a treatment option have led to a significant increase in HCQ use. HCQ poisoning should be at the top-of-mind for emergency providers in cases of toxic ingestion. Treatment for HCQ poisoning includes sodium bicarbonate, epinephrine, and aggressive electrolyte repletion. We highlight the use of hypertonic saline and diazepam.

Case Report

We describe the case of a 37-year-old man who presented to the emergency department after the ingestion of approximately 16 g of HCQ tablets (initial serum concentration 4270 ng/mL). He was treated with an epinephrine infusion, hypertonic sodium chloride, high-dose diazepam, sodium bicarbonate, and aggressive potassium repletion. Persistent altered mental status necessitated intubation, and he was managed in the medical intensive care unit until his QRS widening and QTc prolongation resolved. After his mental status improved and it was confirmed that his ingestion was not with the intent to self-harm, he was discharged home with outpatient follow-up.

Why Should an Emergency Physician Be Aware of This?

For patients presenting with HCQ overdose and an unknown initial serum potassium level, high-dose diazepam and hypertonic sodium chloride should be started immediately for the patient with widened QRS. The choice of hypertonic sodium chloride instead of sodium bicarbonate is to avoid exacerbating underlying hypokalemia which may in turn potentiate unstable dysrhythmia. In addition, early intubation should be a priority in vomiting patients because both HCQ toxicity and high-dose diazepam cause profound sedation.

Comparison of the Mean Minimum Dose of Bolus Oxytocin for Proper Uterine Contraction during Cesarean Section

BACKGROUND

Cesarean section is the most common midwifery operation. The aim of this study is to determine the mean minimum dose of bolus oxytocin for proper uterine contraction during cesarean section.

METHODS

Patients were divided into two groups: elective cesarean section (n=41) and cesarean section due to difficulty in labor (n=42 patients). Patients underwent spinal anesthesia and oxytocin infusion was begun at 30 drops per minute (20 units of oxytocin per 1000 cc serum), and was also administered as a half-dose in cc to achieve effective contraction of the uterus. Meanwhile, the information of patients including systolic and diastolic blood pressure (SBP and DBP), heart rate and amount of bleeding during the operation was recorded in a questionnaire.

RESULTS

In the elective cesarean section group, the average SBP was about 117.10mmHg, average DBP 70.50 mmHg, the amount of bleeding during surgery was 623.63mL, and heart rate was 88.88bpm. In the cesarean section group due to difficulty in labor progress, SBP was 113.5 mmHg, DBP 62.69 mmHg, and bleeding was 573.81mL. In addition, 9 patients in the elective group and 3 patients in the lack of progress group, did not require bolus oxytocin. In the lack of a progress group, 8 patients needed more than 5 doses of oxytocin. In addition, about 10 (12%) of all patients had no side effects, and hypotension.

CONCLUSION

Given that, the minimum effective dose of oxytocin in the elective cesarean section was 1IU, and in those in labor progress was 1-1.5IU, less oxytocin administration represents lesser side effects. It is recommended that patients who are candidates of cesarean section should be administered 1.5IU of oxytocin in the form of bolus.

Ventricular Fibrillation Caused by Primary Carnitine Deficiency

BACKGROUND

Primary carnitine deficiency (PCD) is a rare but potentially life-threatening genetic disorder if left untreated. Although some patients remain asymptomatic lifelong, a few patients present with hepatic encephalopathy, hypoglycemia, cardiomyopathy, dysrhythmia, and even sudden death.

CASE REPORT

A 25-year-old woman with PCD collapsed suddenly while eating lunch. Bystander cardiopulmonary resuscitation (CPR) was performed for 8 min, with automated external defibrillation once before admission. Upon arrival at our emergency department (ED), she was unresponsive without a pulse or spontaneous breathing. The initial heart rhythm on the electrocardiogram monitor was ventricular fibrillation (VF). The medical staff continued CPR with defibrillation for sustained VF. Return of spontaneous circulation (ROSC) was achieved after a total resuscitation time of 14 min, with defibrillation twice after cardiac arrest. The heart rhythm after ROSC was atrial fibrillation, with a rapid ventricular rate initially and subsequent progression to sinus tachycardia with diffuse ST segment depression and a prolonged QT interval. Her low carnitine level was consistent with her underlying disease. Cardiac magnetic resonance imaging and sonography for detection of cardiomyopathy showed no significant findings. With carnitine supplementation for a few days, her plasma carnitine level returned to 30 μM, with no recurrence of ventricular dysrhythmia. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: PCD is rare but could be life-threatening, and compiling detailed histories may help emergency physicians to determine the cause of sudden cardiac death after resuscitation. This information may be used to correct potential underlying problems and prevent recurrence of the condition after treatment.

Implantable loop recorders for cardiac dysrhythmia monitoring

Incorporation of technological advances in healthcare delivery has played a foundational role in development of modern healthcare. With the use of wireless transmission in conjunction with digitization of electrocardiography, continuous monitoring strategies have redefined our approach to dysrhythmia. These devices show promising results in evolving implantable loop recorder technology. In this review, we summarize the history of remote monitoring, indications for loop recorders, devices available, evidence for specific devices and anticipated studies.

Diagnosis and treatment of adults with congenital heart disease

Approximately 50 million adults worldwide have known congenital heart disease (CHD). Among the most common types of CHD defects in adults are atrial septal defects and ventricular septal defects followed by complex congenital heart lesions such as tetralogy of Fallot. Adults with CHDs are more likely to have hypertension, cerebral vascular disease, diabetes and chronic kidney disease than age-matched controls without CHD. Moreover, by the age of 50, adults with CHD are at a greater than 10% risk of experiencing cardiac dysrhythmias and approximately 4% experience sudden death. Consequently, adults with CHD require healthcare that is two- to four-times greater than adults without CHD. This paper discusses the diagnosis and treatment of adults with atrial septal defects, ventricular septal defects and tetralogy of Fallot.

Melatonin Relations with Energy Metabolism as Possibly Involved in Fatal Mountain Road Traffic Accidents

Previous results evidenced acute exposure to high altitude (HA) weakening the relation between daily melatonin cycle and the respiratory quotient. This review deals with the threat extreme environments pose on body time order, particularly concerning energy metabolism. Working at HA, at poles, or in space challenge our ancestral inborn body timing system. This conflict may also mark many aspects of our current lifestyle, involving shift work, rapid time zone crossing, and even prolonged office work in closed buildings. Misalignments between external and internal rhythms, in the short term, traduce into risk of mental and physical performance shortfalls, mood changes, quarrels, drug and alcohol abuse, failure to accomplish with the mission and, finally, high rates of fatal accidents. Relations of melatonin with energy metabolism being altered under a condition of hypoxia focused our attention on interactions of the indoleamine with redox state, as well as, with autonomic regulations. Individual tolerance/susceptibility to such interactions may hint at adequately dealing with body timing disorders under extreme conditions.

P wave dispersion in assessment of dysrhythmia risk in patients with secundum type atrial septal defect and the effect of transcatheter or surgical closure

Atrial dysrhythmia is an important cause of mortality and morbidity in patients with atrial septal defect. Increased P wave duration can predict the risk of atrial dysrhythmia. The aim of this study is to evaluate the risk of atrial dysrhythmia by measuring P wave dispersion, and to observe the effect of surgical and transcatheter closure. Sixty-one patients and 30 controls were investigated. In patient group, before and after closure and in control group at the time of presentation, 12-lead electrocardiography records were evaluated. P wave duration and amplitude, P wave axis, PR interval, P wave dispersion, QRS axis, corrected QT interval, and QT dispersion were calculated. The measurements in patient and control groups, measurements before and after closure, and measurements of surgical and transcatheter group were compared. There were 27 patients in surgical group and 34 patients in transcatheter group. In patient group, signs of right heart volume overload were apparent but there was no significant difference in terms of P wave dispersion between two groups. We compared patient group in itself and found that while the use of medication, cardiothoracic index, ratio of right ventricular dilation, and paradoxical movement in interventricular septum were increased, mean age of closure was younger in surgical group. While P wave dispersion decreased in transcatheter group after closure, it increased in surgical group (p = 0.021). In conclusion, atrial septal defects may cause atrial repolarisation abnormalities and this effect persists even after surgical closure. Transcatheter closure in childhood may decrease dysrhythmia risk in long-term follow-up.

Importance of early diagnosis in LMNA-related muscular dystrophy for cardiac surveillance

INTRODUCTION

The identification of LMNA-related muscular dystrophy is important because it poses life-threatening cardiac complications. However, diagnosis of LMNA-related muscular dystrophy based on clinical features is challenging.

METHODS

We reviewed the clinical phenotypes of 14 children with LMNA variants, focusing on the cardiac function and genotypes.

RESULTS

Most patients presented with motor developmental delay or gait abnormalities. Eight (57%) patients had prominent neck extensor weakness or contractures. All patients showed ankle contractures at an early stage. Regular cardiac surveillance allowed for the detection of dysrhythmias in 57% of patients at a mean age of 14 years (range, 5-26). All patients had missense variants; however, there were no clear phenotype-genotype correlations.

DISCUSSION

Early diagnosis of LMNA-related muscular dystrophy provides an opportunity for cardiac surveillance, potentially leading to the prevention of cardiac mortality in children.

Slow-wave coupling across a gastroduodenal anastomosis as a mechanism for postsurgical gastric dysfunction: evidence for a "gastrointestinal aberrant pathway"

Postsurgical gastric dysfunction is common, but the mechanisms are varied and poorly understood. The pylorus normally acts as an electrical barrier isolating gastric and intestinal slow waves. In this report, we present an aberrant electrical conduction pathway arising between the stomach and small intestine, following pyloric excision and surgical anastomosis, as a novel disease mechanism. A patient was referred with postsurgical gastroparesis following antrectomy, gastroduodenostomy, and vagotomy for peptic ulceration. Scintigraphy confirmed markedly abnormal 4-h gastric retention. Symptoms included nausea, vomiting, postprandial distress, and reflux. Intraoperative, high-resolution electrical mapping was performed across the anastomosis immediately before revision gastrectomy, and the resected anastomosis underwent immunohistochemistry for interstitial cells of Cajal. Mapping revealed continuous, stable abnormal retrograde slow-wave propagation through the anastomosis, with slow conduction occurring at the scar (4.0 ± 0.1 cycles/min; 2.5 ± 0.6 mm/s; 0.26 ± 0.15 mV). Stable abnormal retrograde propagation continued into the gastric corpus with tachygastria (3.9 ± 0.2 cycles/min; 1.6 ± 0.5 mm/s; 0.19 ± 0.12 mV). Histology confirmed ingrowth of atypical ICC through the scar, defining an aberrant pathway enabling transanastomotic electrical conduction. In conclusion, a "gastrointestinal aberrant pathway" is presented as a novel proposed cause of postsurgical gastric dysfunction. The importance of aberrant anastomotic conduction in acute and long-term surgical recovery warrants further investigation.NEW & NOTEWORTHY High-resolution gastric electrical mapping was performed during revisional surgery in a patient with severe gastric dysfunction following antrectomy and gastroduodenostomy. The results revealed continuous propagation of slow waves from the duodenum to the stomach, through the old anastomotic scar, and resulting in retrograde-propagating tachygastria. Histology showed atypical interstitial cells of Cajal growth through the anastomotic scar. Based on these results, we propose a "gastrointestinal aberrant pathway" as a mechanism for postsurgical gastric dysfunction.

The use of heart rate variability analysis to detect arrhythmias in horses undergoing a standard treadmill exercise test

Background

Little is known about normal heart rate variability (HRV) in horses during exercise. It can be difficult to separate premature beats from normal beat‐to‐beat variation at higher heart rates.

Objectives

The aim was to quantify HRV in healthy horses during a high‐speed treadmill‐standardized exercise test (HSET) and to compare with the HRV in horses observed to have arrhythmias during exercise.

Animals

Thirteen healthy horses (Group H), 30 horses with arrhythmias (Group A), and 11 horses with poor performance but no observed arrhythmias (Group O).

Methods

Prospective, observational study. All horses performed a HSET with simultaneous electrocardiograph (ECG) recorded. The ECGs were corrected for artifacts, and arrhythmias noted. Percent instantaneous beat‐to‐beat cycle length variation (% R‐R variation) was calculated, and HRV analyses were performed on trot, canter, and recovery segments.

Results

Group H showed between −4.4 and +3.8% R‐R variation during trot and between −6.1 and +5.4% R‐R variation during the canter phase of the HSET. Group A had significantly larger maximum and 1st percentile R‐R shortening and lengthening compared with Group H and Group O during the recovery phase where most arrhythmias were observed. During recovery, a cutoff of 6% maximum % R‐R shortening predicted the presence of arrhythmia with 88% sensitivity and 97% specificity and likelihood ratio of 26.

Conclusions and Clinical Importance

Healthy horses have little instantaneous R‐R variation during exercise. If a cardiac cycle shortens more than 6% from the previous cycle during the recovery phase, this R‐R interval is likely to represent an arrhythmic event.

Comprehensive review of cardiovascular toxicity of drugs and related agents

Cardiovascular diseases are a leading cause of morbidity and mortality in most developed countries of the world. Pharmaceuticals, illicit drugs, and toxins can significantly contribute to the overall cardiovascular burden and thus deserve attention. The present article is a systematic overview of drugs that may induce distinct cardiovascular toxicity. The compounds are classified into agents that have significant effects on the heart, blood vessels, or both. The mechanism(s) of toxic action are discussed and treatment modalities are briefly mentioned in relevant cases. Due to the large number of clinically relevant compounds discussed, this article could be of interest to a broad audience including pharmacologists and toxicologists, pharmacists, physicians, and medicinal chemists. Particular emphasis is given to clinically relevant topics including the cardiovascular toxicity of illicit sympathomimetic drugs (e.g., cocaine, amphetamines, cathinones), drugs that prolong the QT interval, antidysrhythmic drugs, digoxin and other cardioactive steroids, beta-blockers, calcium channel blockers, female hormones, nonsteroidal anti-inflammatory, and anticancer compounds encompassing anthracyclines and novel targeted therapy interfering with the HER2 or the vascular endothelial growth factor pathway.

Evaluation of anticoagulation status for atrial fibrillation on early ischaemic stroke outcomes: a registry-based, prospective cohort study of acute stroke care in Surrey, UK

OBJECTIVE

The relationship of anticoagulation therapies with stroke severity and outcomes have been well documented in the literature. However, none of the previous research has reported the relationship of atrial fibrillation (AF)/anticoagulation therapies with urinary tract infection (UTI), pneumonia and length of stay in hyperacute stroke units (HASUs). The present study aimed to evaluate AF and anticoagulation status in relation to early outcomes in 1387 men (median age=75 years, IQR=65-83) and 1371 women (median age=83 years, IQR=74-89) admitted with acute ischaemic stroke to HASUs in Surrey between 2014 and 2016.

METHODS

We conducted this registry-based, prospective cohort study using data from the Sentinel Stroke National Audit Programme. Association between AF anticoagulation status with severe stroke on arrival (National Institutes of Health Stroke Scale score ≥16), prolonged HASU stay (>3 weeks), UTI and pneumonia within 7 days of admission, severe disability on discharge (modified Rankin Scale score=4 and 5) and inpatient mortality was assessed by logistic regression, adjusted for age, sex, hypertension, congestive heart failure, diabetes and previous stroke.

RESULTS

Compared with patients with stroke who are free from AF, those with AF without anticoagulation had an increased adjusted risk of having more severe stroke: 5.8% versus 14.0%, OR=2.4 (95% CI 1.6 to 3.6, P<0.001), prolonged HASU stay: 21.5% versus 32.0%, OR=1.4 (1.0-2.0, P=0.027), pneumonia: 8.2% versus 19.1%, OR=2.1 (1.4-2.9, P<0.001), more severe disability: 24.2% versus 40.4%, OR=1.6 (1.2-2.1, P=0.004) and mortality: 9.3% versus 21.7%, OR=1.9 (1.4-2.8, P<0.001), and AF patients with anticoagulation also had greater risk for having UTI: 8.6% versus 12.3%, OR=1.9 (1.2-3.0, P=0.004), pneumonia: 8.2% versus 11.5%, OR=1.6 (1.1-2.4, P=0.025) and mortality: 9.7% versus 21.7%, OR=1.9 (1.4-2.8, P<0.001). The median HASU stay for stroke patients with AF without anticoagulation was 10.6 days (IQR=2.8-26.4) compared with 5.8 days (IQR=2.3-17.5) for those free from AF (P<0.001).

CONCLUSIONS

Patients with AF, particularly those without anticoagulation, are at increased risk of severe stroke, associated with prolonged HASU stay and increased risk of early infection, disability and mortality.

A Perfect Storm: Tyrosine Kinase Inhibitor-Associated Polymorphic Ventricular Tachycardia

BACKGROUND

Oral tyrosine kinase inhibitors (TKIs) are becoming increasingly common in oncology practice due to ease of administration and patient preference. This class of medications is relatively unknown to emergency physicians.

CASE REPORT

Here we present a case of electrical storm (ES) thought to be associated with ibrutinib, a TKI. The ES was unabated despite antidysrhythmic therapy and electrical cardioversion, and was treated with supportive care, which eventually included the use of extracorporeal membrane oxygenation. This patient had no risk factors or apparent causes of recurrent ventricular tachycardia. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: ES has not previously been described with ibrutinib, but may be associated with off-target effects of the drug.

Permanent cardiac pacing in patients with end-stage renal disease undergoing dialysis

BACKGROUND

Studies investigating the risk of cardiac dysrhythmia warranting permanent pacemaker therapy for end-stage renal disease (ESRD) patients are limited. This study investigated the incidence rate of permanent cardiac pacing in dialysis patients.

METHODS

Using the Taiwan National Health Insurance Database, we identified 28 471 newly diagnosed ESRD patients in 2000-2010 [9700 on peritoneal dialysis (PD) and 18 771 on hemodialysis (HD)] and 113 769 randomly selected controls without kidney disease, frequency-matched by sex, age and diagnosis date. We also established propensity score-matched HD and PD cohorts with 9700 patients each. Incidence rates and hazard ratios (HRs) of implantation were evaluated by the end of 2011. Complications were also evaluated among patients with implantation.

RESULTS

The incidence rates of permanent pacemaker implantation were 5.93- and 3.50-fold greater in HD and PD patients than in controls (1.44 and 0.85 versus 0.24 per 1000 person-years, respectively). The adjusted HRs (aHRs) of implantation were 3.26 [95% confidence interval (CI) = 2.41-4.42] and 2.36 (95% CI = 1.56-3.58) for HD and PD patients, respectively, compared with controls. The pacemaker implantation rate was 0.33 per 1000 person-years greater in the propensity score-matched HD cohort than in the PD cohort, with an aHR of 1.30 (95% CI = 0.82-2.05) for the HD cohort compared with the PD cohort.

CONCLUSIONS

Dialysis patients are at an increased risk of dysrhythmia requiring pacemaker implantation compared with the general population. The risks are not significantly different between HD and PD patients.

Vestibulo-ocular reflex function in children with high-functioning autism spectrum disorders

Sensorimotor processing alterations are a growing focus in the assessment and treatment of Autism Spectrum Disorders (ASD). The rotational vestibulo-ocular reflex (rVOR), which functions to maintain stable vision during head movements, is a sensorimotor system that may be useful in understanding such alterations and their underlying neurobiology. In this study, we assessed post-rotary nystagmus elicited by continuous whole body rotation among children with high-functioning ASD and typically developing children. Children with ASD exhibited increased rVOR gain, the ratio of eye velocity to head velocity, indicating a possible lack of cerebellar inhibitory input to brainstem vestibular nuclei in this population. The ASD group also showed less regular or periodic horizontal eye movements as indexed by greater variance accounted for by multiple higher frequency bandwidths as well as greater entropy scores compared to typically developing children. The decreased regularity or dysrhythmia in the temporal structure of nystagmus beats in children with ASD may be due to alterations in cerebellum and brainstem circuitry. These findings could potentially serve as a model to better understand the functional effects of differences in these brain structures in ASD. Autism Res 2017, 10: 251-266. © 2016 International Society for Autism Research, Wiley Periodicals, Inc.

Current conceptual challenges in the study of rhythm processing deficits

Interest in the study of rhythm processing deficits (RPD) is currently growing in the cognitive neuroscience community, as this type of investigation constitutes a powerful tool for the understanding of normal rhythm processing. Because this field is in its infancy, it still lacks a common conceptual vocabulary to facilitate effective communication between different researchers and research groups. In this commentary, we provide a brief review of recent reports of RPD through the lens of one important empirical issue: the method by which beat perception is measured, and the consequences of method selection for the researcher's ability to specify which mechanisms are impaired in RPD. This critical reading advocates for the importance of matching measurement tools to the putative neurocognitive mechanisms under study, and reveals the need for effective and specific assessments of the different aspects of rhythm perception and synchronization.

Multi-channel wireless mapping of gastrointestinal serosal slow wave propagation

BACKGROUND

High-resolution (HR) extracellular mapping allows accurate profiling of normal and dysrhythmic slow wave patterns. A current limitation is that cables traverse the abdominal wall or a natural orifice, risking discomfort, dislodgement or infection. Wireless approaches offer advantages, but a multi-channel system is required, capable of recording slow waves and mapping propagation with high fidelity.

METHODS

A novel multi-channel (n = 7) wireless mapping system was developed and compared to a wired commercial system. Slow wave signals were recorded from the porcine gastric and intestinal serosa in vivo. Signals were simultaneously acquired using both systems, and were filtered and processed to map activation wavefronts. For validation, the frequency and amplitude of detected events were compared, together with the speed and direction of mapped wavefronts.

KEY RESULTS

The wireless device achieved comparable signal quality to the reference device, and slow wave frequencies were identical. Amplitudes of the acquired gastric and intestinal slow wave signals were consistent between the devices. During normal propagation, spatiotemporal mapping remained accurate in the wireless system, however, during ectopic dysrhythmic pacemaking, the lower sampling resolution of the wireless device led to reduced accuracy in spatiotemporal mapping.

CONCLUSIONS & INFERENCES

A novel multichannel wireless device is presented for mapping slow wave activity. The device achieved high quality signals, and has the potential to facilitate chronic monitoring studies and clinical translation of spatiotemporal mapping. The current implementation may be applied to detect normal patterns and dysrhythmia onset, but HR mapping with finely spaced arrays currently remains necessary to accurately define dysrhythmic patterns.

Cardiac stimulation with electronic control device application

BACKGROUND

Electronic control devices (ECDs) are weapons used to incapacitate violent subjects. Subjects have died suddenly after ECD application, but because cardiac dysrhythmias have been inconsistently observed during ECD application in animals, the cause for death is uncertain.

OBJECTIVES

The objective was to identify the factors contributing to cardiac stimulation during ECD application detected by transesophageal echocardiography.

METHODS

Four Yorkshire pigs were anesthetized, paralyzed with vecuronium, and restrained in a supine position. A GE 6T echo probe was placed in the esophagus to directly visualize left ventricular function. M-mode echocardiography was used to estimate heart rate. Two dart locations, chest and abdomen, were assessed. ECD applications were delivered from one of five commercially available devices (Taser X26, Singer S200 AT, Taser M26, Taser X3, and Taser C2) in random order to each pig, four times in each orientation.

RESULTS

Cardiac stimulation, characterized by multiple PVCs or the sudden increase in ventricular contraction rate during application, did not occur with abdominal dart location. With chest dart application in small pigs, cardiac stimulation occurred with all ECDs except with the Taser X3 (p < 0.0001). In large pigs, cardiac stimulation occurred only during chest application of the S200 AT (chest vs. abdomen: 207 beats/min, vs. 91 beats/min, p < 0.0001).

CONCLUSION

Cardiac stimulation occurs during ECD application in pigs, and is dependent upon subject size, dart orientation, and ECD. The Taser X3 did not result in cardiac stimulation in small or large pigs.

A case of commotio cordis treated with therapeutic hypothermia

BACKGROUND

Therapeutic hypothermia is used as a neuroprotective strategy for patients who have persistent neurologic compromise after return of spontaneous circulation from cardiac arrest. The 2010 American Heart Association Guidelines recommend the use of therapeutic hypothermia in adult cardiac arrest patients when the initial rhythm is ventricular fibrillation. These recommendations are based on primary research in patients with a cardiac cause of their ventricular fibrillation.

CASE REPORT

A 43-year-old male was brought to our emergency department (ED) with commotio cordis. He was struck in the chest with a baseball bat, after which he collapsed at the scene and was pulseless. Return of spontaneous circulation was achieved after defibrillation by treating paramedics, and the patient remained comatose on arrival to the ED. He was transferred to the intensive care unit and treated with therapeutic hypothermia at target temperature of 32-34°C. He was extubated on day 3, and discharged home on day 8 with good neurologic function. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: We report a case of commotio cordis in which the adult patient was treated with therapeutic hypothermia and had a favorable outcome. To our knowledge, this is the first reported case of its kind. Evidence for the use of therapeutic hypothermia is incomplete in patients with a traumatic cause of cardiac arrest, such as commotio cordis, despite probable similarities in the pathophysiology of anoxic brain injury. Our case illustrates that there may be benefit from use of therapeutic hypothermia for a broader population than is currently recommended.

Atrial fibrillation with rapid ventricular response resulting from low-voltage electrical injury

BACKGROUND

Cardiac dysrhythmias after electrical injury have been reported previously, however, atrial fibrillation after low-voltage electrical injury is extremely rare. We present a case of atrial fibrillation with rapid ventricular response resulting from a low-voltage electrical injury.

CASE REPORT

A 24-year-old active duty Navy sailor presented to the emergency department after an electrical shock from a 440-V furnace. He experienced severe pain in both hands and a racing sensation in his chest. He denied other symptoms. An electrocardiogram was performed demonstrating atrial fibrillation with a rapid ventricular response (132 beats/min). After analgesia and sedation, synchronized cardioversion (100 J) was performed with complete resolution of cardiac symptoms and restoration of normal sinus rhythm (75 beats/min). Cutaneous wounds were bandaged and the patient was discharged with cardiology follow-up. At follow-up, the patient reported no symptoms and an echocardiogram revealed no structural abnormalities.

CONCLUSIONS

Atrial fibrillation in the setting of electrical injury is rarely reported in the published medical literature. In patients without history suggestive of cardiac structural abnormalities, synchronized cardioversion is a potential option for restoration of normal sinus rhythm and resolution of symptoms after electrical injury-induced atrial fibrillation with rapid ventricular response.

Changing the waveform of circadian rhythms: considerations for shift-work

Circadian disruption in shift-work is common and has deleterious effects on health and performance. Current efforts to mitigate these harms reasonably focus on the phase of the circadian pacemaker, which unfortunately in humans, shifts slowly and often incompletely. Temporal reorganization of rhythmic waveform (i.e., the shape of its 24 h oscillation), rather than phase, however, may better match performance demands of shift-workers and can be quickly and feasibly implemented in animals. In fact, a bifurcated pacemaker waveform may permit stable entrainment of a bimodal sleep/wake rhythm promoting alertness in both night and daylight hours. Although bifurcation has yet to be formally assessed in humans, evidence of conserved properties of circadian organization and plasticity predict its occurrence: humans respond to conventional manipulations of waveform (e.g., photoperiodism); behaviorally, the sleep/wake rhythm is adaptable; and finally, the human circadian system likely derives from the same multiple cellular oscillators that permit waveform flexibility in the rodent pacemaker. In short, investigation into untried manipulations of waveform in humans to facilitate adjustment to challenging schedules is justified.

Using a virtual cortical module implementing a neural field model to modulate brain rhythms in Parkinson's disease

We propose a new method for selective modulation of cortical rhythms based on neural field theory, in which the activity of a cortical area is extensively monitored using a two-dimensional microelectrode array. The example of Parkinson's disease illustrates the proposed method, in which a neural field model is assumed to accurately describe experimentally recorded activity. In addition, we propose a new closed-loop stimulation signal that is both space- and time- dependent. This method is especially designed to specifically modulate a targeted brain rhythm, without interfering with other rhythms. A new class of neuroprosthetic devices is also proposed, in which the multielectrode array is seen as an artificial neural network interacting with biological tissue. Such a bio-inspired approach may provide a solution to optimize interactions between the stimulation device and the cortex aiming to attenuate or augment specific cortical rhythms. The next step will be to validate this new approach experimentally in patients with Parkinson's disease.

Review article: gastric electrical stimulation for gastroparesis--physiological foundations, technical aspects and clinical implications

BACKGROUND

Application of electrical stimulation to the gut, primarily the stomach, has rapidly advanced in the last two decades, from mostly animal studies to the clinical arena. Most studies focused on the use of electrical stimulation for gastroparesis, the only approved indication for such intervention.

AIM

To review the physiological basis of gastric electrical activity and the technical aspects and clinical outcome of gastric electrical stimulation (GES) for gastroparesis.

METHODS

PubMed search from 1966 to 2009, using gastroparesis and GES as search terms. Areas in focus were systematically reviewed.

RESULTS

The literature consists of open-label studies, mostly from single centres, published in the last decade. Improvement in symptoms, quality of life and nutritional status was reported by most studies. Physiologically, stimulation parameters approved in clinical practice do not regulate gastric slow wave activity and have inconsistent effect on gastric emptying. The mechanism of action of GES is not fully known, but data support modulation of gastric biomechanical activity and afferent neural mechanisms.

CONCLUSIONS

Gastric electrical stimulation is a helpful intervention in recalcitrant gastroparesis. Controlled studies and better understanding of mechanisms of action of electrical stimulation are needed to evaluate further the clinical utility of this intervention and to exploit its therapeutic potential better.

A placebo-controlled study examining the effect of allopurinol on heart rate variability and dysrhythmia counts in chronic heart failure

AIMS

Allopurinol improves endothelial function in chronic heart failure by reducing oxidative stress. We wished to explore if such an effect would attenuate autonomic dysfunction in CHF in line with many other effective therapies in CHF.

METHODS

We performed a prospective, randomized, double-blind cross-over study in 16 patients with NYHA Class II-IV chronic heart failure (mean age 67 +/- 10 years, 13 male, comparing allopurinol (2 months) at a daily dose of 300 mg (if creatinine < 150 micromol l-1) or 100 mg (if creatinine > 150 micromol l-1) with matched placebo. Mean heart rate and dysrhythmia counts were recorded from 24 h Holter tapes at monthly intervals for 6 months. We assessed autonomic function using standard time domain heart rate variability parameters (HRV): SDNN, SDANN, SDNN index, rMSSD and TI.

RESULTS

Allopurinol had no significant effect on heart rate variability compared with placebo; the results are expressed as a difference in means +/- s.d. with 95% confidence interval (CI) between allopurinol and placebo: SDNN mean = 6.5 +/- 4.8 ms, P = 0.18 and 95% CI (-3.7, 17); TI mean = -2.1 +/- 1.4, P = 0.16 and 95% CI (-5.2, 0.8); SDANN mean = -2.8 +/- 7 ms, P = 0.68 and 95% CI (-18, 12); SDNNi mean = 2 +/- 6.6, P = 0.7 and 95% CI (-12, 16); RMSSD mean = -0.9 +/- 2, P = 0.68 and 95% CI (-5.6, 3.7). For mean heart rate the corresponding results were 0.9 +/- 1.4, P = 0.5 and 95% CI (-2, 3.8). Log 24 h ventricular ectopic counts (VEC) were 0.032 +/- 0.37, P = 0.7 and 95% CI (-0.1, 0.2). Patient compliance with study medication was good since allopurinol showed its expected effect of reducing plasma uric acid (P < 0.001).

CONCLUSIONS

Allopurinol at doses, which are known to reduce oxidative stress appear to have no significant effect on resting autonomic tone, as indicated by time domain heart rate variability or on dysrhythmia count in stable heart failure patients.