Ictal ECG-based assessment of sudden unexpected death in epilepsy.

Introduction: Previous case-control studies of sudden unexpected death in epilepsy (SUDEP) patients failed to identify ECG features (peri-ictal heart rate, heart rate variability, corrected QT interval, postictal heart rate recovery, and cardiac rhythm) predictive of SUDEP risk. This implied a need to derive novel metrics to assess SUDEP risk from ECG. Methods: We applied Single Spectrum Analysis and Independent Component Analysis (SSA-ICA) to remove artifact from ECG recordings. Then cross-frequency phase-phase coupling (PPC) was applied to a 20-s mid-seizure window and a contour of -3 dB coupling strength was determined. The contour centroid polar coordinates, amplitude (alpha) and angle (theta), were calculated. Association of alpha and theta with SUDEP was assessed and a logistic classifier for alpha was constructed. Results: Alpha was higher in SUDEP patients, compared to non-SUDEP patients (p < 0.001). Theta showed no significant difference between patient populations. The receiver operating characteristic (ROC) of a logistic classifier for alpha resulted in an area under the ROC curve (AUC) of 94% and correctly classified two test SUDEP patients. Discussion: This study develops a novel metric alpha, which highlights non-linear interactions between two rhythms in the ECG, and is predictive of SUDEP risk.

Random effects inducing heart pathological dynamics: An approach based on mathematical models.

This work deals with an investigation of randomness effects on heart rhythm analysis. A mathematical model composed by three-coupled nonlinear oscillators coupled by time-delayed connections is employed for this aim. In this regard, heart rhythm is governed by delayed-differential equations. Nondeterministic aspects are incorporated considering random connections among oscillators. The main idea is to show that nonlinearities and randomness define together the great variety of possibilities in the heart dynamical system. In general, results corroborate that the model is able to capture the main behaviors of the cardiac system showing that pathological behaviors can evolve from normal rhythms due to random couplings. Experimental data corroborate this argues pointing that nonlinear dynamical analysis is useful for a proper physiological comprehension.

ECG Interpretation Using the CRISP Method: A Guide for Nurses.

Nurses often struggle with identifying electrocardiogram (ECG) rhythms, but rapidly interpreting these rhythms is an essential skill that every nurse should master, especially in the perioperative setting. The CRISP (Cardiac Rhythm Identification for Simple People) method is an algorithm designed to help nurses rapidly interpret ECGs. Key aspects of assisting patients with suspected cardiac issues include the nursing assessment, correct three-lead ECG placement, and calculation of the heart rate. Then the perioperative nurse can use the steps of the CRISP method to identify nursing actions related to specific arrhythmias, including determining whether QRS complexes are present, P waves are present, and QRS complexes are wide or narrow or whether there are more P waves than QRS complexes.

Epidemiology and outcomes in out-of-hospital cardiac arrest: a report from the NEDIS-based cardiac arrest registry in Korea.

Sudden cardiac death (SCD) is a significant issue affecting national health policies. The National Emergency Department Information System for Cardiac Arrest (NEDIS-CA) consortium managed a prospective registry of out-of-hospital cardiac arrest (OHCA) at the emergency department (ED) level. We analyzed the NEDIS-CA data from 29 participating hospitals from January 2008 to July 2009. The primary outcomes were incidence of OHCA and final survival outcomes at discharge. Factors influencing survival outcomes were assessed as secondary outcomes. The implementation of advanced emergency management (drugs, endotracheal intubation) and post-cardiac arrest care (therapeutic hypothermia, coronary intervention) was also investigated. A total of 4,156 resuscitation-attempted OHCAs were included, of which 401 (9.6%) patients survived to discharge and 79 (1.9%) were discharged with good neurologic outcomes. During the study period, there were 1,662,470 ED visits in participant hospitals; therefore, the estimated number of resuscitation-attempted CAs was 1 per 400 ED visits (0.25%). Factors improving survival outcomes included younger age, witnessed collapse, onset in a public place, a shockable rhythm in the pre-hospital setting, and applied advanced resuscitation care. We found that active advanced multidisciplinary resuscitation efforts influenced improvement in the survival rate. Resuscitation by public witnesses improved the short-term outcomes (return of spontaneous circulation, survival admission) but did not increase the survival to discharge rate. Strategies are required to reinforce the chain of survival and high-quality cardiopulmonary resuscitation in Korea.

Epidemiology and Outcomes in Out-of-hospital Cardiac Arrest: A Report from the NEDIS-Based Cardiac Arrest Registry in Korea

Sudden cardiac death (SCD) is a significant issue affecting national health policies. The National Emergency Department Information System for Cardiac Arrest (NEDIS-CA) consortium managed a prospective registry of out-of-hospital cardiac arrest (OHCA) at the emergency department (ED) level. We analyzed the NEDIS-CA data from 29 participating hospitals from January 2008 to July 2009. The primary outcomes were incidence of OHCA and final survival outcomes at discharge. Factors influencing survival outcomes were assessed as secondary outcomes. The implementation of advanced emergency management (drugs, endotracheal intubation) and post-cardiac arrest care (therapeutic hypothermia, coronary intervention) was also investigated. A total of 4,156 resuscitation-attempted OHCAs were included, of which 401 (9.6%) patients survived to discharge and 79 (1.9%) were discharged with good neurologic outcomes. During the study period, there were 1,662,470 ED visits in participant hospitals; therefore, the estimated number of resuscitation-attempted CAs was 1 per 400 ED visits (0.25%). Factors improving survival outcomes included younger age, witnessed collapse, onset in a public place, a shockable rhythm in the pre-hospital setting, and applied advanced resuscitation care. We found that active advanced multidisciplinary resuscitation efforts influenced improvement in the survival rate. Resuscitation by public witnesses improved the short-term outcomes (return of spontaneous circulation, survival admission) but did not increase the survival to discharge rate. Strategies are required to reinforce the chain of survival and high-quality cardiopulmonary resuscitation in Korea.

Continuous monitoring of cardiac rhythms in left ventricular assist device patients.

Monitoring of cardiac rhythms is of major importance in the treatment of heart failure patients with left ventricular assist devices (LVADs) implanted. A continuous surveillance of these rhythms could improve out-of-hospital care in these patients. The aim of this study was to investigate cardiac rhythms using available pump data only. Datasets (n = 141) obtained in the normal ward, in the intensive care unit, and during bicycle ergometry were analyzed in 11 recipients of a continuous flow LVAD (59.1 ± 9.7 years; male 82%). Tachograms and arrhythmic patterns derived from the pump flow waveform, and a simultaneously recorded ECG were compared, as well as heart rate variability parameters such as: the average heart beat duration (RR interval), the standard deviation of the beat duration (SDNN), the root-mean-square of the difference of successive beat durations (RMSSD), and the number of pairs of adjacent beat duration differing by >50 ms divided by the number of all beats (pNN50). A very good agreement of cardiac rhythm parameters from the pump flow compared with ECG was found. Tachycardia, atrial fibrillation, and extrasystoles could be accurately identified from the tachograms derived from the pump flow. Also, Bland-Altman analysis comparing pump flow with ECG indicated a very small difference in average RR interval of 0.3 ± 1.0 ms, in SSDN of 0.5 ± 2.7 ms, in RMSSD of 1.0 ± 5.6 ms, and in pNN50 of 0.3 ± 1.0%. Continuous monitoring of cardiac rhythms from available pump data is possible. It has the potential to reduce the out-of-hospital diagnostic burden and to permit a more efficient adjustment of the level of mechanical support.

Changes of cardiac rhythms in a swine model of adult asphyxial cardiac arrest / 中华急诊医学杂志

Objective To observe the changes of cardiac rhythms in a swine model of adult asphyxia! cardiac arrest. Method Sixteen Pigs were aphyxiated by endotracheal tube clamping until 8 min after loss of aortic pulsations. Resuscitation was then provided and swinds were assigned to received 0.045 mg/kg epinephrine intravenously after 3 min of basic life support. The animals with restoration of spontaneous circulation within 20 min from CPR were defined as successfully resuscitated, while the rest were identified as unresuscitation. Electrocardiogram ( EGG) were monitored from the start of asphyxia to the start of the CPR. Results When loss of pulsations occurred, 2 of 16 animals had ventricular fibrillation; 10 pigs exhibited pulseless electrical activity, and 4 pigs had asystole. During the 8 min after the loss of aortic pulsations, pulseless electrical activity converted to VF in 7 pigs. Immidiatedly prior to resuscitation, VF occurred in 9 pigs, asystole in 4 pigs, and PEA in 3 pigs. Conclusions Most of animals in this swine model of asphyxial cardiac arrest presented PEA, but most of them converted to VF especially late in the asphyxial process.

Actividad rítmica del músculo papilar inducida por estimulación de alta frecuencia: ritmos n:1, formas de transición e histéresis / Arrhytmic actiitty of the papilary muscle induced by high frecuency stimulatiion: rhythm n:1, transition forms and hysteresis

Los tejidos cardíacos son capaces de trabajar en un amplio intervalo de frecuencias con el fin de atender las distintas demandas que el organismo impone al sistema cardiovascular. Sin embargo, bajo un régimen de cambios de frecuencia y con ciertas condiciones patológicas, pueden desarrollarse arritmias, como bloqueos, taquicardias, fibrilaciones, etc. de posibles consecuencias fatales. Esto motiva la realización de diversos arreglos experimentales en los cuales se explora el comportamiento del corazón, o de regiones de éste. En este artículo reportamos diversos fenómenos que ocurren en el músculo papilar de cobayo cuando se le estimula eléctricamente, desde una frecuencia basal de un pulso por segundo (pps) hasta frecuencias muy altas, de varias decenas de pps, pero incrementando paulatinamente la frecuencia de estimulación. Describimos que en nuestras condiciones experimentales, el músculo despliega sucesivamente ritmos tipo n:1 (una respuesta cada n estímulos) con n creciente; encontramos también que entre uno y otro de estos ritmos aparecen diversas formas de transición, entre las cuales describimos una totalmente nueva en este sistema, que hemos denominado por "ráfagas"; finalmente mostramos que este sistema exhibe de manera generalizada histéresis en la frecuencia, siendo el primer reporte que se hace para esta especie y además el primer reporte en el que se muestran varias "asas" o regiones de histéresis por frecuencia dentro de una misma excursión experimental. Debido al gran volumen de datos generados, hemos introducido una forma de presentación y análisis concisa y eficiente, basada en los espectros de potencia de los datos obtenidos a través de la transformada rápida de Fourier. Este método también se describe brevemente en el artículo.

Cardiac tissues are able to work within a wide range of frequencies to respond to the changing requirements an organism may have. However, during these frequency variations and under certain pathologic conditions arrhythmias such as blocks, tachycardia, fibrillation, etc, may arise some with fatal consequences. For this reason several experimental procedures have been developed that have shown to be useful in studying whole heart properties, or as an alternative from portions of it when changes in its work rate are imposed. This study reports different phenomena occurring in the papillary muscle of the guinea pig heart when stimulated at very high frequency, of several tens of pps, while analyzing its responses during gradual increments starting at 1 (pulses per second). We found that in our conditions papillary muscles display N:1 rhythms with progressive higher N; further more we found that between one and the next rhythm diverse transition patterns appear, among them a new one that we have named "burst pattern". Finally we show that our system exhibits a generalized process of hysteresis by frequency, being this the first report for guinea pig cardiac tissue and the first one to show also the presence of several hysteresis loops in the same experiment. Due to the large volume of generated data we used a faster and easier way to analyze and display them, based on the fast Fourier transform (FFT). The method is briefly described. (Arch Cardiol Mex 2004; 74:11-24).