Cardiac Instability Research Articles

N-octanoyl dopamine is superior to dopamine in protecting graft contractile function when administered to the heart transplant recipients from brain-dead donors

The major source of heart transplantation comes from brain-dead (BD) donors. However, brain death and myocardial ischemia/reperfusion injury during transplantation may lead to cardiac dysfunction and hemodynamic instability. A previous work demonstrated that pre-treatment of BD donors with dopamine improved the graft survival of heart allograft in recipient after transplantation. However, low-dose dopamine treatment might result in tachycardia and hypertension. Our previous experimental study showed that pre-treatment of BD donor rats with the dopamine derivate N-octanoyl dopamine (NOD), devoid of any hemodynamic effects, improved graft function after transplantation. Herein, we hypothesized that NOD confers superior myocardial protection than dopamine, in terms of graft function. Male Lewis donor rats were either subjected to sham-operation or brain death via a subdurally placed balloon followed by 5.5 h monitoring. Then, the hearts were explanted and heterotopically transplanted into Lewis recipient rats. Shortly before the onset of reperfusion, continuous intravenous infusion of either NOD (14.7 μg/kg/min, BD + NOD group, n = 9), dopamine (10 μg/kg/min, BD + Dopamine group, n = 8) or physiological saline vehicle (sham, n = 9 and BD group, n = 9) were administered to the recipient rats. In vivo left-ventricular (LV) graft function was evaluated after 1.5 h reperfusion. Additionally, immunohistochemical detection of 4-hydroxy-2-nonenal (HNE, an indicator of oxidative stress) and nitrotyrosine (a nitro-oxidative stress marker), was performed. After heart transplantation, systolic and diastolic functions were significantly decreased in the BD group compared to sham. Treatment with NOD but not dopamine, resulted in better LV graft systolic functional recovery (LV systolic pressure BD + NOD 90 ± 8 vs BD + Dopamine 66 ± 5 vs BD 65 ± 4 mmHg; maximum rate of rise of LV pressure dP/dtmax BD + NOD 2686 ± 225 vs BD + Dopamine 2243 ± 70 vs BD 1999 ± 147 mmHg/s, at an intraventricular volume of 140 μl, p < 0.05) and myocardial work compared to BD group. The re-beating time (time to restoration of heartbeat) was significantly shorter in BD + NOD group than that of BD hearts (32 ± 4 s vs. 48 ± 6 s, p < 0.05), Dopamine treatment had no impact on all of these parameters. Furthermore, NOD as well as dopamine decreased HNE and nitrotyrosine immunoreactivity to the same level. NOD is superior to dopamine in terms of protecting LV graft contractile function when administered to the heart transplant recipients from BD donors.

Selective chemical ablation of transient receptor potential vanilloid 1 expressing neurons in the left stellate ganglion protects against ischemia-induced ventricular arrhythmias in dogs

ObjectivesFindings from prior investigations show that left stellate ganglion (LSG) inhibitory approaches protect the heart from ventricular arrhythmias (VAs) caused by acute myocardial infarction (AMI), which still remain many side effects. Targeted transient receptor potential vanilloid 1/tyrosine hydroxylase (TRPV-1/TH) expressing sympathetic neurons ablation is a novel neuro-ablative strategy. The aim of this investigation was to explore if targeted molecular neuro-ablative strategy by resiniferatoxin (RTX) stellate microinjection could protect against ischemia-induced VAs. MethodsTwenty-four anesthetized beagles were assigned to a control group (n = 12) and RTX group (n = 12) in a random manner. Targeted molecular neuro-ablative was produced by RTX stellate microinjection and DMSO was microinjected into LSG in the same way as control. Plasma norepinephrine (NE) level, heart rate variability (HRV), Tpeak-Tend interval (Tp-Te), LSG neural activity and function, ventricular effective refractory period (ERP), beat-to-beat variability of repolarization (BVR) and ventricular action potential duration (APD) were measured at baseline and 60 min after RTX or DMSO microinjection. AMI model was established by the ligation of left anterior descending coronary artery and 60-minute electrocardiography was continuously recorded for VAs analysis. Subsequently, HRV, Tp-Te, plasma NE level from jugular vein and coronary sinus, LSG neural activity and function, ventricular ERP, ventricular APD, BVR, action potential duration alternans (APDA) cycle length and ventricular fibrillation threshold (VFT) were evaluated after AMI. Finally, tissue collection of LSG was performed for examining the TRPV-1, nerve growth factor (NGF) protein and c-fos protein. ResultsTRPV-1 was highly expressed in the TH-expressing neurons and RTX injection significantly ablated TRPV-1/TH-positive neurons in LSG. Compared with baseline, RTX stellate microinjection significantly reduced plasma NE level, the sympathetic component of HRV, LSG neural activity and LSG function, shortened Tp-Te, prolonged ventricular ERP and APD, but there were no remarkable differences existed for control group. AMI resulted in the significant raise in plasma NE level from jugular vein and coronary sinus, the sympathetic component of HRV, LSG neural activity and LSG function, the marked prolongation in Tp-Te and BVR, the significant decrease in ERP and APD from ischemia area, and the increase in APDA cycle length in the ischemic region of the control group, which were remarkably attenuated in the RTX group. RTX pretreatment markedly rose the VFT in the RTX group. Furthermore, the AMI-triggered VAs was significantly prevented by RTX injection in the RTX group. RTX microinjection down-regulated significantly TRPV-1, NGF and c-fos expression in the LSG compared with the control group. ConclusionTargeted ablation of TRPV-1/TH positive sympathetic neurons induced by RTX stellate microinjection could suppress ischemia-induced cardiac autonomic imbalances and cardiac electrophysiology instability to protect against AMI-induced VAs.

P6383Cardiac output during targeted temperature management and renal function after out-of-hospital cardiac arrest

Abstract Background After resuscitation from out-of-hospital cardiac arrest (OHCA), renal injury and hemodynamic instability are common. Low blood pressure during targeted temperature management (TTM) is associated with acute renal injury (AKI). The aim of this study is to test the hypothesis, that low cardiac output during TTM is associated with acute kidney injury after OHCA. Methods Single-center substudy of 171 patients included in the prospective, randomized TTM-trial. Hemodynamic evaluation was performed with serial measurements by pulmonary artery catheter. Mean arterial pressure ≥65 mmHg and central venous pressure of 10 to 15 mmHg were hemodynamic treatment goals. Acute kidney injury (AKI) was the primary endpoint and was defined according to the KDIGO-criteria. Differences between groups were tested by repeated measurements mixed models. Measurements and main results Of 152 patients with available hemodynamic data, 49 (32%) had AKI and 21 (14%) had AKI with need for renal replacement therapy (RRT) in the first three days. At admission, cardiac index was higher in the AKI-group (mean (confidence interval): 2.6 (2.2–3.0) L/min/m2 versus 2.2 (2.0–2.3) L/min/m2, p=0.003). During 24 hours of targeted temperature management, patients with AKI had increased heart rate (11 beats/min, pgroup&lt;0.0001) and increased lactate (1 mmol/L, pgroup&lt;0.0001) compared to patients without AKI. However, there was no overall difference in cardiac index (pgroup = 0.25) (Figure). In multivariate models, adjusting for potential confounders including targeted temperature, mean arterial pressure (odds ratio: 0.69 (0.50–0.96) per 5 mmHg increase, p=0.03), heart rate (1.04 (1.01–1.08) per beat/min increase, p=0.01) and lactate (1.59 (1.14–2.2) per mmol/L increase, p=0.006) were independently associated with AKI, but cardiac index remained unrelated with AKI. Figure 1 Conclusions Blood pressure, heart rate and lactate, but not cardiac output, during 24 hours of targeted temperature management were associated with renal injury in comatose OHCA-patients. Acknowledgement/Funding The research fund Gangstedfonden and the Research fund of Rigshospitalet has supported this study with unrestricted salary in Dr. Grand's PhD project.

Feasibility and Challenges of Microsurgical Resection of Colloid Cysts in Patients with Preexisting Ventriculoperitoneal Shunts

Colloid cysts are the most common third ventricular tumor and may present with symptoms related to obstructive hydrocephalus. Although definitive endoscopic or microsurgical resection is the standard of care, patients may receive temporizing ventriculoperitoneal shunts when definitive management is deferred. Subsequent definitive treatment can be challenging because of the ventricular collapse and narrowing of the operative corridor. There is currently no literature evaluating the feasibility of definitive colloid cyst resection in patients with preexisting ventriculoperitoneal shunts. We retrospectively reviewed records for patients undergoing colloid cyst resection between 2009 and 2019 to identify patients with preexisting shunts prior to surgery. Three patients had preexisting ventriculoperitoneal shunts. Two patients had been shunted at outside institutions where microsurgical or endoscopic resection was not available. One patient received a shunt from an outside surgeon when she was deemed a poor surgical candidate because of cardiac instability. All 3 patients underwent successful gross total colloid cyst resection via the transcallosal approach without recurrences during a mean follow-up of 4.2 years. All patients had intact cognitive and memory function and returned to work. Surgical resection of colloid cysts is possible despite a preexisting ventriculoperitoneal shunt. Because the ventricular space may be collapsed postoperatively because of cerebrospinal fluid diversion, a transcortical route (either endoscopic or microscopic) can be complicated by a small operative corridor with reduced visibility. The transcallosal approach was safe and feasible in these cases for providing midline access with adequate visualization for complete resection despite ventricular collapse.

Loss of consciousness at onset of aneurysmal subarachnoid hemorrhage in good-grade patients.

Loss of consciousness (LOC) at presentation with aneurysmal subarachnoid hemorrhage (aSAH) has been associated with early brain injury and poor functional outcome. The impact of LOC on the clinical course after aSAH deserves further exploration. A retrospective analysis of 149 aSAH patients who were prospectively enrolled in the Cerebral Aneurysm Renin Angiotensin Study (CARAS) between 2012 and 2015 was performed. The impact of LOC was analyzed with emphasis on patients presenting in excellent or good neurological condition (Hunt and Hess 1 and 2). A total of 50/149 aSAH patients (33.6%) experienced LOC at presentation. Loss of consciousness was associated with severity of neurological condition upon admission (Hunt and Hess, World Federation of Neurosurgical Societies (WFNS), Glasgow Coma Scale (GCS) grade), hemorrhage burden on initial head CT (Fisher CT grade), acute hydrocephalus, cardiac instability, and nosocomial infection. Of Hunt and Hess grade 1 and 2 patients, 21/84 (25.0%) suffered LOC at presentation. Cardiac instability and nosocomial infection were significantly more frequent in these patients. In multivariable analysis, LOC was the predominant predictor of cardiac instability and nosocomial infection. Loss of consciousness at presentation with aSAH is associated with an increased rate of complications, even in good-grade patients. The presence of LOC may identify good-grade patients at risk for complications such as cardiac instability and nosocomial infection.

Extracorporeal rewarming from experimental hypothermia: Effects of hydroxyethyl starch versus saline priming on fluid balance and blood flow distribution.

What is the central question of this study? Mortality in accidental hypothermia patients rewarmed by extracorporeal circulation remains high. Knowledge concerning optimal fluid additions for extracorporeal rewarming is lacking, with no apparent consensus. Does colloid versus crystalloid priming have different effects on fluid balance and blood flow distribution during extracorporeal rewarming? What is the main finding and its importance? In our rat model of extracorporeal rewarming from hypothermic cardiac arrest, hydroxyethyl starch generates less tissue oedema and increases circulating blood volume and organ blood flow, compared with saline. The composition of fluid additions appears to be important during extracorporeal rewarming from hypothermia. Rewarming by extracorporeal circulation (ECC) is the recommended treatment for accidental hypothermia patients with cardiac instability. Hypothermia, along with initiation of ECC, introduces major changes in fluid homeostasis and blood flow. Scientific data to recommend best practice use of ECC for rewarming these patients is lacking, and no current guidelines exist concerning the choice of priming fluid for the extracorporeal circuit. The primary aim of this study was to compare the effects of different fluid protocols on fluid balance and blood flow distribution during rewarming from deep hypothermic cardiac arrest. Sixteen anaesthetized rats were cooled to deep hypothermic cardiac arrest and rewarmed by ECC. During cooling, rats were equally randomized into two groups: an extracorporeal circuit primed with saline or primed with hydroxyethyl starch (HES). Calculations of plasma volume (PV), circulating blood volume (CBV), organ blood flow, total tissue water content, global O2 delivery and consumption were made. During and after rewarming, the pump flow rate, mean arterial pressure, PV and CBV were significantly higher in HES-treated compared with saline-treated rats. After rewarming, the HES group had significantly increased global O2 delivery and blood flow to the brain and kidneys compared with the saline group. Rats in the saline group demonstrated a significantly higher total tissue water content in the kidneys, skeletal muscle and lung. Compared with crystalloid priming, the use of an iso-oncotic colloid prime generates less tissue oedema and increases PV, CBV and organ blood flow during ECC rewarming. The composition of fluid additions appears to be an important factor during ECC rewarming from hypothermia.

Cardiac output during targeted temperature management and renal function after out-of-hospital cardiac arrest

PurposeAfter resuscitation from out-of-hospital cardiac arrest (OHCA), renal injury and hemodynamic instability are common. We aimed to assess the association between low cardiac output during targeted temperature management (TTM) and acute kidney injury (AKI) after OHCA. Materials and methodsSingle-center substudy of 171 patients included in the prospective, randomized TTM-trial. Hemodynamic evaluation was performed with serial measurements by pulmonary artery catheter. AKI was the primary endpoint and was defined according to the KDIGO-criteria. ResultsOf 152 patients with available hemodynamic data, 49 (32%) had AKI and 21 (14%) had AKI with need for renal replacement therapy (RRT) in the first three days. During targeted temperature management, patients with AKI had higher heart rate (11 beats/min, pgroup < 0.0001), higher mean arterial pressure (MAP) (4 mmHg, pgroup = 0.001) and higher lactate (1 mmol/L, pgroup < 0.0001) compared to patients without AKI. However, there was no difference in cardiac index (pgroup = 0.25). In a multivariate logistic regression model, adjusting for potential confounders, MAP (p = .03), heart rate (p = .01) and lactate (p = .006), but not cardiac output, were independently associated with AKI. ConclusionsBlood pressure, heart rate and lactate, but not cardiac output, during 24 h of TTM were associated with AKI in comatose OHCA-patients.

Resistant Ventricular Arrhythmia and the Role of Overdrive Pacing in the Suppression of the Electrical Storm

Ventricular arrhythmia storm is a state of cardiac instability characterized by multiple ventricular arrhythmias or multiple ICD therapies within a 24-hour duration. Management of this life-threatening state depends on the reversal of the cause besides either electrical or medical management of the arrhythmia. We report a case of a 54-year-old male who underwent a percutaneous coronary intervention following massive acute myocardial infarction. Afterwards, he developed frequent life-threatening ventricular arrhythmias that required multiple shocks and antiarrhythmic medications. Despite all these interventions, it was very difficult to control the electrical instability, but after overdrive ventricular pacing, the storm subsided and within a few days the case was stabilized. Overdrive pacing is an easy temporary modality to control the resistant arrhythmia following myocardial infarction.

Central Ambulatory Veno-Arterial Extracorporeal Membrane Oxygenation in Lung Transplantation

Purpose Central veno-arterial (VA) ECMO provides reliable cardiopulmonary support in selected patients with end-stage lung diseases and severe pulmonary hypertension or cardiac instability. Ambulation dramatically improves patient outcomes. We investigated the outcomes of a new technique of ambulatory central VA ECMO via tunneled cannula insertion and right thoracotomy. Methods Candidates for lung transplantation who required respiratory and cardiac support were taken to the operating room for central VA ECMO cannulation. In the OR, the right 3rd rib is identified and a medial segment is removed. The pericardium is opened and pursestrings are placed on the mid-ascending aorta and right atrial appendage. Aortic and venous cannula are advanced through 1cm incisions lateral to the thoracic incision. Heparin is administered and the aorta and right atrium are then cannulated. A chest tube is placed and the incision is closed. A prospectively maintained institutional database was analyzed. All patients who were cannulated for central ECMO via right thoracotomy for the purpose of ambulatory circulatory support were included. Results Fifteen patients underwent central VA-ECMO cannulation from April 2016 to July 2018 via the above technique. The mean age was 51 (range 29-67). 8 (53%) were male. The indications for VA ECMO were end-stage lung diseases and pulmonary hypertension/cardiac instability in all patients. 12 patients ultimately underwent lung transplantation, and 3 patients expired prior to definitive therapy. The mean duration of ECMO support was 546.4 hours (range of 46-2004 hours). All patients were either ambulatory while on ECMO, or able to stand. One patient had post-operative bleeding requiring return to the operating room. One patient had an embolic cerebrovascular event without residual deficits. All patients who survived to transplantation were discharged from the hospital. Conclusion We describe a central ECMO cannulation strategy that allows ambulation while avoiding the vascular, infectious, and flow limiting issues associated with alternative site cannulation. The above technique offers a minimal access approach that allows full pre-transplant optimization with an acceptable risk profile.

Effect of myocardial heterogeneity on ventricular electro-mechanical responses: a computational study

BackgroundThe heart wall exhibits three layers of different thicknesses: the outer epicardium, mid-myocardium, and inner endocardium. Among these layers, the mid-myocardium is typically the thickest. As indicated by preliminary studies, heart-wall layers exhibit various characteristics with regard to electrophysiology, pharmacology, and pathology. Construction of an accurate three-dimensional (3D) model of the heart is important for predicting physiological behaviors. However, the wide variability of myocardial shapes and the unclear edges between the epicardium and soft tissues are major challenges in the 3D model segmentation approach for identifying the boundaries of the epicardium, mid-myocardium, and endocardium. Therefore, this results in possible variations in the heterogeneity ratios between the epicardium, mid-myocardium, and endocardium. The objective of this study was to observe the effects of different thickness ratios of the epicardium, mid-myocardium, and endocardium on cardiac arrhythmogenesis, reentry instability, and mechanical responses during arrhythmia.MethodsWe used a computational method and simulated three heterogeneous ventricular models: Model 1 had the thickest M cell layer and thinnest epicardium and endocardium. Model 2 had intermediate layer thicknesses. Model 3 exhibited the thinnest mid-myocardium and thickest epicardium and endocardium. Electrical and mechanical simulations of the three heterogeneous models were performed under normal sinus rhythm and reentry conditions.ResultsModel 1 exhibited the highest probability of terminating reentrant waves, and Model 3 exhibited to experience greater cardiac arrhythmia. In the reentry simulation, at 8 s, Model 3 generated the largest number of rotors (eight), while Models 1 and 2 produced five and seven rotors, respectively. There was no significant difference in the cardiac output obtained during the sinus rhythm. Under the reentry condition, the highest cardiac output was generated by Model 1 (19 mL/s), followed by Model 2 (9 mL/s) and Model 3 (7 mL/s).ConclusionsA thicker mid-myocardium led to improvements in the pumping efficacy and contractility and reduced the probability of cardiac arrhythmia. Conversely, thinner M cell layers generated more unstable reentrant spiral waves and hindered the ventricular pumping.

Dynamic Changes of Cardiac Repolarization Instability during Exercise Testing.

Physical exercise triggers efferent cardiac sympathetic activation. Here, we tracked the spatiotemporal properties of cardiac repolarization on a beat-to-beat basis throughout a standardized exercise test and hypothesized a detectable change at the point of the anaerobic threshold (AT). The study included 20 healthy adults (age 35.3 ± 6.7 yr) undergoing a standardized incremental exercise test on a cycle ergometer. During exercise testing, high-resolution (2000 Hz) ECG monitoring in Frank lead configuration was performed. Three-dimensional beat-to-beat repolarization instability (dT°) was assessed by a novel vector-based method according to a previously published technology. In parallel, the lactate threshold (LT) was detected according to Dickhuth and Mader. We could identify a characteristic pattern of dT° signal during exercise testing. With increasing physical activity, dT° increased concordantly to heart rate. At an average of 164 ± 38 W, dT° and heart rate abruptly showed a discordant behavior, characterized by a transient drop of dT°. The maximal discordance between dT° and heart rate was defined as ATdT° and highly significantly correlated with LTDickhuth (r = 0.841, P < 0.001) and LTMader (r = 0.819, P < 0.001), which were at 156 ± 39 and 172 ± 46 W, respectively. The characteristic of dT° could not be provoked by fast atrial pacing in the absence of exercise. Repolarization instability shows a characteristic pattern during standardized exercise in healthy individuals that allows for a noninvasive estimation of AT.

Perfil do risco cardiovascular de mulheres adultas triadas para um programa de exercício físico

O objetivo do estudo foi descrever o perfil de risco cardiovascular (RCV) de mulheres adultas triadas para participação de um programa de exercício físico. Foram avaliadas 409 mulheres, com idade entre 20 e 59 anos. Seguiu-se a recomendação de triagem e estratificação do RCV proposta pelo Colégio Americano de Medicina Esportiva por meio da aplicação de um questionário face a face que identificou o Risco Alto (RA) pela presença de doença cérebro-cardiovascular ou sintomas de instabilidade cardíaca, Risco Moderado pela presença de três ou mais fatores de risco e o Risco Baixo pela presença de até dois fatores de risco para mulheres com idade inferior a 55 anos. Entretanto, para atender ao desfecho primário do estudo (prevalência do alto risco) foram agrupadas as categorias de risco baixo e moderado (RBM). A frequência das mulheres para o RA foi de 35,2%, sendo: 22,9% cardiopatas, 56,9% apresentavam dispneia, 45,1% vertigem e 32,6% dor no peito. A frequência de mulheres classificadas como RBM, foi de 64,8%. O fator de risco mais prevalente foi a obesidade, sendo 47,5% no RBM e 61,8% no RA, seguido da hipertensão para o RA (43,1%). Houve correlação entre RA e hipertensão (r=0,193; p&lt;0,01); diabetes (r=0,108; p&lt;0,05); obesidade (r=0,158; p&lt;0,01) e sintomatologia climatérica (r=0,150; p&lt;0,01). Para o RA, não houve diferença estatisticamente significante na proporção de mulheres que se autodeclaram hipertensas (χ²=0,071; p&gt;0,05) e diabéticas (χ²= 0,500; p&gt;0,05). Entretanto, houve diferença significante em favor de uma maior proporção de mulheres obesas e que foram classificadas na condição cardiovascular de RA (χ²= 6,367; p =0,01). Em conclusão, há grande prevalência de mulheres classificadas como RA, reforçando a importância da triagem pré-participação ao exercício.

Beta-blockers in Septic Shock

The therapy of patients suffering from sepsis and septic shock is one of the greatest challenges in critical care medicine. In the initial phase of septic shock patients often present with hyperdynamic circulatory conditions with elevated cardiac index, tachycardia and progressive hemodynamic instability. The type of tachycardia differs from atrial fibrillation or flatter to sinus tachycardia. The latter might be persistent even in case of adequate volume therapy according to the surviving sepsis campaign recommendations and may represent an independent pathology due to adrenergic overstimulation. Despite predominantly β2-mediated immunomodulatory effects the administration of a selective β1-adrenergic blocker may be beneficial in some cases. On the other hand, incautious administration of beta-blockers especially in case of insufficient volume replacement may result in direct negative inotropic effects rapidly aggravating hypotension and shock. This review focused on pharmacology of the β-adrenergic system, the pathophysiological rationale and current literature on clinical practice of the use of beta-blockers in sepsis and septic shock.

Surgical Treatment of the Medullary Cavernous Malformations: 53 Cases

The aim of this study was to investigate patient clinical features, surgical complications and outcomes, and the prognostic risk factors of surgical treatment of cavernous malformations (CMs) involving the medulla oblongata. The charts of 53 patients who underwent surgical treatment for CMs involving the medulla oblongata between 2011 and 2017 were reviewed retrospectively. Patient demographics, lesion characteristics, operative documents, and patient outcomes were examined. The study population consisted of 53 patients, with a male/female ratio of 1.4 and a mean age of 32.6 years. Eighteen patients (34.0%) had respiratory dysfunction, and 2 patients (3.8%) had cardiac instabilities, preoperatively. The mean modified Rankin Scale score was 2.7 on admission. Gross total resection was achieved in 52 patients (98.1%). Postoperatively, 23 patients (43.4%) had respiratory dysfunction, and 16 patients (30.2%) had dysphagia or cough. The mean follow-up duration was 35.7 months. At the last follow-up evaluation, the mean modified Rankin Scale score was 1.7, and 42 patients (84%) had favorable outcomes, with mRS scores ≤2. The conditions of the patients improved in 34 cases (68%), remained unchanged in 10 cases (20%), and worsened in 6 cases (12%) relative to the preoperative baseline. The independent adverse factors for long-term outcome were age ≥50 years and increased time of reservation of tracheal intubation after surgery. Surgical treatment of CMs involving the medulla oblongata was challenging, notably, perioperative respiratory dysfunction, with which patients tend to have unfavorable long-term outcomes, especially for elder patients.

Positive Airway Pressure for Sleep-Related Breathing Disorders in Heart Failure—Overview and Discussion of Potential Mechanisms of Harm

The impact of positive airway pressure (PAP) therapies on cardiovascular outcome in obstructive sleep apnea (OSA) and central sleep apnea (CSA) is currently under debate. The goal of this review is to critically analyze the current findings and discuss hypotheses on benefits or even harm in patients with heart failure (HF). While PAP sufficiently improves OSA, symptoms and cardiac parameters, the SAVE trial failed to show survival benefits. However, it was limited due to low adherence, non-sleepy population and maximal cardiac pre-treatment. SERVE-HF showed increased mortality in secondary analysis in patients with severe systolic HF with predominant CSA under adaptive servo-ventilation (ASV). Criticism of the trial emanated from high crossover, low compliance, use of older devices, and contradictory beneficial results in other studies. As sudden cardiac deaths was the reported main cause of mortality, influences of pre-medication and methods of pressure support on cardiac instability may have contributed to the pathogenesis. OSA and CSA are main risk factors for poor outcome in cardiovascular disease. However, the effect of CPAP and ASV on cardiovascular comorbidities and prognosis requires further evaluation. Further insights from ongoing trials are urgently needed to clarify benefits and risk.

Sternal semi-closure using a bioresorbable osteosynthesis device: a new method for delayed sternal closure.

To evaluate the safety and efficacy of our new delayed sternal closure (DSC) method, involving sternal semi-closure using a bioresorbable osteosynthesis device and complete skin closure. Between 2013 and 2017, 36 patients underwent DCS at our hospital. The patients were divided into two groups based on the method used for DSC. The later conventional DSC group consisted of 18 patients undergoing late complete sternal closure following fixation of pulmonary and hemodynamic instability, and the new DSC group consisted of 18 patients undergoing early sternal semi-closure a few days after surgery. In the new DSC group, the sternum was fixed with Super Fixsorb MX40, followed by complete skin closure. Respiratory and hemodynamic conditions, such as systolic blood pressure, cardiac index, tidal volume, and regional oxygen saturation, were significantly more stable in the new DCS group than in the conventional DSC group. The hospital stay was also significantly shorter in the new DSC group. Although there were no serious complications, one patient from the new DCS group suffered deformity of the sternum, which was managed successfully. The sternal semi-closure method decreases pulmonary and cardiac instability during DSC, making early DSC possible.

Spiral breakup in a RD system of cardiac excitation due to front–back interaction

We consider a two-variable partial differential equations model of cardiac excitation and study spiral wave instability in a one-parameter family of solutions. We investigate numerically the existence of periodic traveling wave solution and show the front and the back interaction far away from the bifurcation point in one dimension. In two dimensions, we show the emergence of a stable spiral pattern before the bifurcation point. The most complex spatiotemporal pattern is called ventricular fibrillation when the breakup of one spiral wave makes another wave and the medium becomes chaotic. We show spiral wave instability and periodic traveling wave instability in the same computational settings. It is found that the pattern of the front–back interaction in two dimensions is similar with that of in the one dimension.

Real-Time Closed Loop Diastolic Interval Control Prevents Cardiac Alternans in Isolated Whole Rabbit Hearts.

Cardiac alternans, a beat-to-beat alternation in action potential duration (APD), can lead to fatal arrhythmias. During periodic pacing, changes in diastolic interval (DI) depend on subsequent changes in APD, thus enhancing cardiac instabilities through a 'feedback' mechanism. Recently, an anti-arrhythmic Constant DI pacing protocol was proposed and shown to be effective in suppressing alternans in 0D and 1D in silico studies. However, previousexperimental validation of Constant DI pacingin the heart has been unsuccessful due to the spatio-temporal complexity of 2D cardiac tissue and the technical challenges in its real-time implementation. Here, we developed a novel closed loop system to detect T-waves from real-time ECG data, enabling successful implementation of Constant DI pacing protocol, and performed high-resolution optical mapping experiments on isolated whole rabbit hearts to validate its anti-arrhythmic effects. The results were compared with: (1) Periodic pacing (feedback inherent) and (2) pacing with heart rate variability (HRV) (feedback modulation) introduced by using either Gaussian or Physiological patterns. We observed that Constant DI pacingsignificantly suppressed alternans in the heart, while maintaining APD spatial dispersion and flattening the slope of the APD restitution curve, compared to traditional Periodic pacing. In addition, introduction of HRV in Periodicpacing failed to prevent cardiac alternans, and was arrhythmogenic.

Early prognosis and predictor analysis for positive coronary angiography after out-of-hospital cardiac arrest (OHCA)

Background: Key predictors of survival after OHCA have been described in the literature. Current guidelines recommend emergency angiography in patients without an obvious extra-cardiac cause of arrest. However, the value of this strategy is debated. Moreover, diagnosis of acute coronary ischaemia after OHCA remains challenging, especially in patients without ST-segment elevation.Objectives: The primary objective was to identify qualitative variables associated with an increased chance of 30-d survival after OHCA. The secondary objective was to identify predictors of 30-d survival among patients with ischaemic cardiomyopathy and patients without ST-segment elevation. Afterwards, we sought to identify parameters associated with acute coronary ischaemia and positive coronary angiography in patients without ST-segment elevation.Methods: Retrospective single-centre study including 123 patients resuscitated from OHCA. Baseline characteristics, resuscitation settings and angiographic findings were analysed.Results: The predictors of 30-d survival after OHCA included witnessed cardiac arrest, haemodynamic instability and coronary angiography. Convertible cardiac rhythm, history of coronary disease and presence of at least two cardiovascular risk factors were associated with acute coronary ischaemia. Predictors for a positive angiography in patients without ST-segment elevation included history of coronary disease, gender, diabetes, dyslipidaemia and presence of at least two cardiovascular risk factors (all p < .05).Conclusions: We identified qualitative predictors of 30-day survival after OHCA. Our findings suggest that the recognition of acute coronary ischaemia after OHCA might be improved. The identification of risk criteria may help to select the best candidates for emergency angiography.

The role of endothelial nitric oxide synthase −786 T/C polymorphism in cardiac instability following aneurysmal subarachnoid hemorrhage

IntroductionCardiac abnormalities are observed frequently after aneurysmal subarachnoid hemorrhage (aSAH). A subset of aSAH patients develops neurogenic cardiomyopathy, likely induced by catecholamine excess. Genetic polymorphisms of the endothelial nitric oxide synthase (eNOS) gene have been linked to decreased nitric oxide (NO) levels, coronary artery spasm, and myocardial infarction. The role of the eNOS single nucleotide polymorphism (SNP) −786 T/C in cardiac instability following aSAH has not been previously investigated. MethodsFrom 2012 to 2015, aSAH patients were prospectively enrolled in the Cerebral Aneurysm Renin Angiotensin System (CARAS) study at two academic institutions. Blood samples were used to assess the eNOS SNP -786 T/C rs2070744 through 5'exonuclease (Taqman) genotyping assays. Associations between this polymorphism and cardiac instability following aSAH were analyzed. ResultsMultivariable analysis demonstrated a dominant effect of the C allele of eNOS SNP -786 T/C on cardiac instability in patients with aSAH. A lower Glasgow Coma Scale score and a history of ischemic vascular disease were also associated with cardiac instability. Furthermore, cardiac instability independently predicted poor functional outcome upon discharge from the hospital. ConclusionsThe C allele of the eNOS SNP -786 T/C was independently associated with an increased risk for cardiac instability following aSAH. Cardiac instability itself was a risk factor for an unfavorable functional outcome upon discharge from the hospital.