Electrical Defibrillation Research Articles

NON-UNIFORMITY OF THE DISTRIBUTION OF ELECTRICAL TRANSMEMBRANE POTENTIALS IN CARDIAC DEFIBRILLATION

The need for emergency cessation of ventricular fibrillation is one of the problems of modern reanimatology. In spite of searches for novel methods, there is the only effective method — electrical cardiac defibrillation. Objective: to investigate the effect of different forms of pulses on cell membranes in a model experiment and to assess their use for effective cardiac defibrillation. Materials and methods. The Maxwell model was used for theoretical analysis of the spatial distribution of an electric field in the red blood cell membrane. The electric effect on a single cell was calculated using the experimental findings and the equivalent electrical circuit of the myocardial structure during a defibrillation procedure. The cardiomyocyte membrane potential upon exposure to defibrillator discharge was estimated. Exposure of the red blood cell membrane to single, two unipolar and two heteropolar pulses was examined. Results. There is non-additivity of speeds upon double exposure as compared to single one. Single pulse causes a lower effect of electroporation than two double pulses. Hyperpolarization and depolarization processes in the cardiomyocyte membranes occur successively during electrical cardiac defibrillation. Conclusion. Two heteropolar pulses cause an effect of biological membrane electroporation with a greater probability than two unipolar ones.

Short period of mild hypothermia improves resuscitation outcome in a porcine model of prolonged ventricular fibrillation

Objective To investigate the resuscitation outcome after a short period of mild hypothermia in porcine model of prolonged ventricular fibrillation (VF). Methods Fourteen male healthy domestic swine weighting 34 to 36 kg were used. VF was induced electrically and maintained untreated for 11 mins, followed by manual cardiopulmonary resuscitation (CPR) procedure. Two investigators initiated chest compression and bag-valve mask ventilation in pattern of 2 min rotation. A biphasic wave of 120 J electric defibrillation (ED) was attempted 6 mins after CPR. If there was no return of spontaneous circulation (ROSC), CPR was restored and ED was delivered when necessarily. Resuscitation was considered unsuccessful if absence of ROSC for 12 mins. However, if ROSC occurred, animals were randomly(random number) diveded into normothermia (NT) group and hypothermia treatment (CH) group. Animals in CH group were immediately cooled by using intravenous infusion of ice-cold saline and surface cooling. Core temperature was reduced to 32-34 degrees centigrade within 120 mins and maintained at this level for 2 h. Active rewarming was completed within 2 h until baseline body temperature was reached. Data of hemodynamic variables, blood-gas analysis and blood lactate before VF of two groups were recorded. Meawhile, cardiac output (CO), heart rate and Tc after ROSC were recorded. Neurological defect scores (NDS) were evaluated every 24 h until 96 h after ROSC. Variables were compared using either Fisher test or repeated measures analysis of variance, followed by Bonferroni for multiple comparisons. A two-sided P value<0.05 was regarded statistically significant. Results There was no significant difference in body weight, mean arterial pressure, CO, pH, pressure of end-tidal carbon dioxide (ETCO2) and lactate between groups before VF. In the period of CPR, there were also no significant difference in total resuscitation time, first shock success rate, ROSC rate, shock ROSC rate, total number of shock and doses of epinephrine. However, animals in CH group survived longer time than that in NT groups [（96.00±0.00)h vs (49.71±43.65)h,P=0.031]. Meanwhile, the survival rate of 96 h was significantly higher in CH than that in NT (P<0.05). For neurological function, there was a obviously better NDS in CH group than that in NT group within ROSC 96 h (P<0.05). Conclusion Even a short duration of 2 hour mild hypothermia could improve resuscitation outcome in porcine model of 11 minute VF. Key words: Cardiopulmonary resuscitation; Mild hypothermia; Short duration; Resuscitation outcome

3D Cardiac Electrical Activity Model

The aim of this study is to develop a new, computationally-efficient, anatomically-realistic 3D bidomain cardiac electrical activity model using widely available software and standard low-cost hardware. The model incorporates whole-heart embedded in a human torso, spontaneous activation of sinoatrial node and specialized conduction system with heterogeneous action potential morphologies. The model is capable of generating realistic body surface electrocardiograms (ECGs) and is proposed as a useful tool for investigating some major issues in heart pathophys-iology and in stimulation; such as simulating and optimizing synchronized electrical cardioversion, defibrillation and pacing stimulation.

Cardioprotective Effect of Reamberin in Ischemic — Reperfusion Injury

Objective: to identify the effectiveness of the drug Reamberin in complex intensive threatment of patients with cardiac surgery in heart fibrillation and remodeling of prosthetic heart valves and plastic defects of atrial and ventricular septa. Reamberin according the following protocol: 400 ml in the first 6 hours of the postoperative period as an intravenous drip at a rate of 60—90 drops/min. In group 2 (control group), 26 patients received standard intensive care medication. In addition to standard clinical and laboratory tests during the study following components were quantitavile determined in blood: troponin I, lactate dehydrogenase, creatine kinase, isofractions of creatine kinase MB, transaminases (alanine aminotransferase and aspartate aminotransferase). Results. Treatment of patients from the main group revealed the recovery of functional parametersof the myocardium, improved dynamics of cardiac enzymes and normalization of blood acid-base status. Conclusion. Inclusion in the complex intensive therapy of post#cardiac surgery of the Reamberin in patients experiencing heart fibrillation after the cardiopulmonary bypass followed by electrical defibrillation improved the clinical course of the early postoperative period and reduced the risk of complications and early mortality.

PDE constrained optimization of electrical defibrillation in a 3D ventricular slice geometry.

A computational study of an optimal control approach for cardiac defibrillation in a 3D geometry is presented. The cardiac bioelectric activity at the tissue and bath volumes is modeled by the bidomain model equations. The model includes intramural fiber rotation, axially symmetric around the fiber direction, and anisotropic conductivity coefficients, which are extracted from a histological image. The dynamics of the ionic currents are based on the regularized Mitchell-Schaeffer model. The controls enter in the form of electrodes, which are placed at the boundary of the bath volume with the goal of dampening undesired arrhythmias. The numerical optimization is based on Newton techniques. We demonstrated the parallel architecture environment for the computation of potentials on multidomains and for the higher order optimization techniques.

Low-energy defibrillation with multi-electrodes stimulation: A simulation study.

The objective of this study is to explore the possible ways to reduce defibrillation energy and further reveal the mechanism of electric defibrillation. A bidomain simulation study was performed on a rabbit whole-ventricle electrophysiological model and the feasibility of the defibrillation strategy with multi-electrodes stimulation was verified. Simulation results indicate that the new approach is effective in low-energy defibrillation.

Jacob Chose Hospice: A Critique of Invasive End-of-Life Care

Jacob Chose Hospice: A Critique of Invasive End-of-Life Care

A Grouped Up-and-Down Method Used for Efficacy Comparison Between Two Different Defibrillation Waveforms.

Electrical defibrillation, which consists of delivering a therapeutic dose of the electrical current to the fibrillating heart with the aid of a defibrillator, is still the only effective way to treat life-threatening ventricular fibrillation (VF). However, the efficacy of electrical therapy for terminating VF is highly dependent on the waveform applied. When new defibrillation waveforms or techniques are developed, their efficacy needs to be accurately evaluated and compared to those in use. A common method for the comparison of defibrillation efficacy is to estimate and compare the individual defibrillation threshold (DFT) by constructing dose response curves or using an up-and-down method. Since DFT is calculated by repetitive and sequential shocks, there will be variability for each measurement and for each individual. This creates a considerable uncertainty for paired comparison. In this paper, a novel grouped up-and-down method is developed for the comparison of defibrillation efficacy between two different defibrillation waveforms or techniques. The efficacy of two commonly used biphasic defibrillation waveforms was compared in a porcine model of cardiac arrest using the developed method. Experimental results demonstrate that the proposed method is more sensitive for efficacy comparison and requires less defibrillation attempts compared with traditional DFT methods.

Resuscitation

The primary aim of cardiopulmonary resuscitation after cardiac arrest is to achieve the return of spontaneous circulation (ROSC). However, following ROSC the clinical and neurologic outcome is mainly influenced by adequate treatment in the postresuscitation period. There are several novel recommendations in the current 2010 guidelines of the European Resuscitation Council (ERC) concerning advanced life support (ALS). In addition to established standards for mechanical, electrical (defibrillation), and pharmacological resuscitation during the initial phase, the guidelines moreover deal with recommendations for standardized therapy in the postresuscitation period. Major aspects concerning the therapy of the postcardiac arrest syndrome include temperature management with therapeutic hypothermia, mechanical ventilation and the extent of oxygenation and blood glucose control. Thus, the initial cardiopulmonary resuscitation and the following postresuscitation treatment have to be considered as merging therapy concepts. Only a standardized therapeutic approach in these different phases of treatment will result in successful resuscitation with high rates of survival and good neurologic outcome.

Decreased repolarization reserve increases defibrillation threshold by favoring early afterdepolarizations in an in silico model of human ventricular tissue.

Sudden cardiac death due to ventricular fibrillation is the largest cause of death in the industrialized world. 1 Zheng Z.J. Croft J.B. Giles W.H. Mensah G.A. Sudden cardiac death in the United States, 1989 to 1998. Circulation. 2001; 104: 2158-2163 Crossref PubMed Scopus (1332) Google Scholar The most effective way for terminating ventricular fibrillation is electrical defibrillation, which is the application of a strong electrical shock to the heart via a set of electrodes placed on the body surface or directly in the heart itself (implantable devices). Because such a shock is painful and can damage the tissue, it is of paramount importance to understand the factors determining the defibrillation threshold (DFT) and how these factors relate to the underlying type of arrhythmia and the affected cardiac tissue. Therefore, several experimental, theoretical, and clinical investigations have been performed to determine DFT. 2 Pidlaoan J.S. Singh V. Bharadwaj J.A. Carrillo M.P. High defibrillation threshold: the science, signs and solutions. Indian Pacing Electrophysiol J. 2010; 10: 21-39 PubMed Google Scholar

Wearable sensors in syncope management.

Syncope is a common disorder with a lifetime prevalence of about 40%. Implantable cardiac electronic devices, including implantable loop recorders (ILR) and implantable cardioverter-defibrillators (ICD), are well established in syncope management. However, despite the successful use of ILR and ICD, diagnosis and therapy still remain challenging in many patients due to the complex hemodynamic interplay of cardiac and vascular adaptations during impending syncopes. Wearable sensors might overcome some limitations, including misdiagnosis and inappropriate defibrillator shocks, because a variety of physiological measures can now be easily acquired by a single non-invasive device at high signal quality. In neurally-mediated syncope (NMS), which is the most common cause of syncope, advanced signal processing methodologies paved the way to develop devices for early syncope detection. In contrast to the relatively benign NMS, in arrhythmia-related syncopes immediate therapeutical intervention, predominantly by electrical defibrillation, is often mandatory. However, in patients with a transient risk of arrhythmia-related syncope, limitations of ICD therapy might outweigh their potential therapeutic benefits. In this context the wearable cardioverter-defibrillator offers alternative therapeutical options for some high-risk patients. Herein, we review recent evidence demonstrating that wearable sensors might be useful to overcome some limitations of implantable devices in syncope management.

The effect of lidocaine and amiodarone on prevention of ventricular fibrillation in patients undergoing coronary artery bypass grafting.

Ventricular fibrillation is common after aortic declamping in patients undergoing open heart surgery. This situation has a negative impact on morbidity and mortality. The aim of this prospective study was to compare the effect of administering lidocaine versus amiodarone before aortic declamping during elective coronary bypass grafting, paying close attention to when the initial effect of amiodarone sets in. In this double blind, prospective, randomized, controlled study, 86 patients who were candidates for elective coronary artery bypass grafting were recruited into three groups: group lidocaine (group L, n=29); group amiodarone (group A, n=27); and group placebo (group P, n=30). Group L patients received 1.5 mg/kg of lidocaine 2 minutes before aortic declamping and group A patients received 300 mg of amiodarone intravenously 15 minutes before release of the aortic cross clamp. The primary endpoints were the incidence of ventricular fibrillation and the number of shocks required to terminate ventricular fibrillation. The frequency of ventricular fibrillation occurrence was significantly higher in group P (70%) when compared with group A (37%) and group L (38%) (P=.017). There was no statistically significant difference between the amiodarone and the lidocaine groups regarding ventricular fibrillation. However, when ventricular fibrillation occurred, the percentage of patients requiring electrical defibrillation was significantly higher in both group L and group P when compared with group A (P=.023). We suggest that during coronary arterial bypass surgery, administration of an amiodarone regime before release of the aortic cross clamp, paying particular attention to the start of the initial effect of amiodarone, is no more effective than lidocaine for prevention from arrhythmia; however, amiodarone reduces the need for electrical defibrillation.

A clinical analysis of 188 cases of pregnancy complicated with critically heart disease

To investigate the factors that affect the outcome of pregnancies complicated with critically heart disease admitt ed to obstetric Intensive Care Unit (ICU). A retrospective study was conducted for 188 pregnant and postpartum patients complicated with heart disease who were admitted to the ICU in West China Second University Hospital from July 2009 to March 2013. During the 4 years, there were 619 cases of pregnancy complicated with heart disease hospitalization. Among them, 188 (30.37%) patients complicated with severe heart disease were admitted to the ICU, accounting for 39.17% of the total ICU admission (480); the mean maternal age was (28.45 ± 6.08) years old and the mean gestational time was (36.03 ± 4.19) weeks. 23 (12.23%) patients received regular antenatal care in our hospital. 61 (32.45%) patients never received antenatal care before hospitalization. Among them, 5 patients were dead. The ratio for diagnosis of heart disease before pregnancy, during pregnancy and after admission were 39.89%, 25.54% and 34.57%, respectively; the most common heart diseases during pregnancy were congenital cardiac disease (80, 42.55%) and rheumatic heart disease (45, 23.94%) followed by arrhythmias (20, 10.64%). The most common complication were pulmonary arterial hypertension (51, 27.13%), arrhythmias (47, 25.00%) and severe heart failure (30, 15.96%); the cardiac function of 164 (87.23%) patients was at stage I-II and 5 (2.66% ) patients died when discharged from hospital. 151 (80.32%) patients received multidisciplinary consultation and 34 (18.09%) used central venous catheterization to control central venous pressure (CVP). 21 (11.17%) patients required mechanical ventilation. 11 (5.85%) patients required emergency life support (cardiopulmonary resuscitation 9 + electric defibrillation 3). Pregnancy complicated with heart disease is the leading reason for admission to ICU. The congenital cardiac disease, rheumatic heart disease and arrhythmias are the main heart diseases during pregnancy. Multidisciplinary cooperation and intensive care are the key measures to improve the outcomes of patients with critically illness. It is very important for reduction of the maternal mortality rate through strengthening preconception care and antenatal care.

История электрической дефибрилляции с древнейших времен и до наших дней

История электрической дефибрилляции с древнейших времен и до наших дней

Myocardial protective effect of hypoxic preconditioning with double cardiopulmonary bypass in canine hearts

Objective To investigate the myocardial protective effect of hypoxic preconditioning in thein vivo canine hearts.Methods Healthy beagle dogs were randomly divided into two groups:the hypoxic preconditioning group (HPC group,n =8) and the control group (C group,n =8).The dog model of the double cardiopulmonary bypass (systemic and coronary circulation) was established after chest opening under general anesthesia.In HPC group,dog hearts were perfused by the coronary circulation and subjected to hypoxic preconditioning (3 min of hypoxia followed by 5 min of reoxygenation,repeated 3 times).The animals in C group were not subjected to hypoxic preconditioning.Both groups underwent cold cardioplegia perfusion through coronary circulation to induce cardiac arrest.At 60 min after cardiopulmonary bypass,we observed one-time rebeat rate,the incidence of arrhythmia and electric defibrillation times.At 30 min after rebeating,the left anterior descending coronary arteries were ligated with suture at the lower 1/3.The myocardial infarction area size was observed 60 min later,and samples were taken for examination by electron microscopy.At T1 (before operation),T2 (before cardiopulmonary bypass),T3 (immediately after the rebeat),and T4 (30 min after the ligation of left anterior descending coronary),the troponin and myocardial enzymes spectrum were measured.Cardiac function and myocardial structure were also observed in both groups.Results Myocardial enzymes at T3 were higher in HPC group than in C group (P ＜ 0.05),and myocardial enzymes and troponin at T4 were significantly lower in HPC group (P ＜ 0.05).As compared with C group,one-time rebeat rate and defibrillation times were significantly reduced in HPC group (7/8 vs.4/8 and 1/8 vs.5/8,P＜0.05).The infarct area size was significantly smaller in HPC group than in C group [(15.37 ± 1.64) ％ vs.(29.77 ± 3.38) ％,P ＜ 0.05],and electron microscopy revealed that the damage of mitochondrial structure and edema of cardiomyocytes were significantly reduced in HPC group as compared with C group.Conclusion Hypoxia preconditioning of the whole heart in vivo had protective effect on myocardia.It could improve the tolerance of myocardia to hypoxic injury. Key words: Hypoxic preconditioning; Cardiopulmonary bypass; Myocardial protection

Rapidly switching multidirectional defibrillation: Reversal of ventricular fibrillation with lower energy shocks

Cardiac arrest after open surgery has an incidence of approximately 3%, of which more than 50% of the cases are due to ventricular fibrillation. Electrical defibrillation is the most effective therapy for terminating cardiac arrhythmias associated with unstable hemodynamics. The excitation threshold of myocardial microstructures is lower when external electrical fields are applied in the longitudinal direction with respect to the major axis of cells. However, in the heart, cell bundles are disposed in several directions. Improved myocardial excitation and defibrillation have been achieved by applying shocks in multiple directions via intracardiac leads, but the results are controversial when the electrodes are not located within the cardiac chambers. This study was designed to test whether rapidly switching shock delivery in 3 directions could increase the efficiency of direct defibrillation. A multidirectional defibrillator and paddles bearing 3 electrodes each were developed and used in vivo for the reversal of electrically induced ventricular fibrillation in an anesthetized open-chest swine model. Direct defibrillation was performed by unidirectional and multidirectional shocks applied in an alternating fashion. Survival analysis was used to estimate the relationship between the probability of defibrillation and the shock energy. Compared with shock delivery in a single direction in the same animal population, the shock energy required for multidirectional defibrillation was 20% to 30% lower (P < .05) within a wide range of success probabilities. Rapidly switching multidirectional shock delivery required lower shock energy for ventricular fibrillation termination and may be a safer alternative for restoring cardiac sinus rhythm.

Pathophysiology of the Heart and Clinical Cardiac Anesthesiology

The paper analyzes the results of the investigations made at the V. A. Negovsky Research Institute of General Reanimatology, Russian Academy of Medical Sciences, on the pathophysiology and applied aspects of cardiac performance and the anesthetic maintenance of cardiac operations. The main tasks presented to its investigators were to improve electric cardiac defibrillation and cardioversion, to elaborate the optimal infusiotransfusion therapy tactics during cardiac surgery, to optimize intraoperative myocardial protection, to maintain lung functions under extracorporeal circulation, to search for the most effective and safe schemes of general and epidural anesthesia in cardiosurgical patients, and to substantiate algorithms for their postoperative activation. The findings could solve the problem of treating circulatory disorders in the practice of critical care medicine on a new plane. At the same time new areas of a further scientific search have been identified.

Microparticles and sudden cardiac death due to coronary occlusion. The TIDE (Thrombus and Inflammation in sudden DEath) study.

The pattern of coronary occlusion might contribute to the onset of ventricular arrhythmia and sudden cardiac death (SCD). We hypothesized that the concentrations of microparticles might differ between SCD and ST-elevation myocardial infarction (STEMI) patients without rhythmic disturbances. The study sample includes consecutive patients hospitalized in two French tertiary centres between 2006 and 2011 for SCD with angiographically-proven acute coronary occlusion (n=23), for STEMI (n=61) and for a planned percutaneous coronary angioplasty (PCI) (n=35, controls). During PCI blood was collected in the arch of aorta (systemic blood) before and after the procedure and in the culprit coronary lesion with an aspiration catheter. Microparticles were analysed by flow cytometry in a blinded manner to quantify endothelial (CD144+), platelet (CD41+), leucocyte (CD11a+) and erythrocyte (CD235a+) derived microparticles. After multivariate analysis, intracoronary concentrations of endothelial-derived microparticles were significantly higher in SCD than in STEMI patients (129 (74-185) vs. 50 (21-118) nb/µl; p < 0.01). Intracoronary and systemic blood concentrations of platelet-derived microparticles were not different between SCD and controls, suggesting limited impact of cardiac massage and electric defibrillation in microparticle concentrations. The higher concentrations of endothelial-derived microparticles in SCD due to acute coronary occlusion compared with STEMI without rhythmic disturbances suggests different patterns of acute coronary occlusion.

A shocking past: a walk through generations of defibrillation development.

Defibrillation is one of the most successful and widely recognized applications of electrotherapy. Yet the historical road to its first successful application in a patient and the innovative adaptation to an implantable device is marred with unexpected turns, political and personal setbacks, and public and scientific condemnation at each new idea. Driven by dedicated scientists and ever-advancing creative applications of new technologies, from electrocardiography to high density mapping and computational simulations, the field of defibrillation persevered and continued to evolve to the life-saving tool it is today. In addition to critical technological advances, the history of defibrillation is also marked by the plasticity of the theory of defibrillation. The advancing theories of success have propelled the campaign for reducing the defibrillation energy requirement, instilling hope in the development of a painless and harmless electrical defibrillation strategy.

Does Ephaptic Coupling Contribute to Propagation in Cardiac Tissue?

Does Ephaptic Coupling Contribute to Propagation in Cardiac Tissue?