Research Progress of External Defibrillation Technique and Its Application / 中国医疗器械杂志

Defibrillator is an important first aid equipment with people attach importance to life and health in today, people pay more attention to the development of defibrillator. This paper reviews the development history of the defibrillator, gives a brief introduction to the structure and working principle of the defibrillator, and then analyzes the key technology of defibrillator, compares the mainstream products on the market and prospects the development trend of defibrillator.

Role of peak current in conversion of patients with ventricular fibrillation

<p><b>INTRODUCTION</b>Peak currents are the final arbiter of defibrillation in patients with ventricular fibrillation (VF). However, biphasic defibrillators continue to use energy in joules for electrical conversion in hopes that their impedance compensation properties will address transthoracic impedance (TTI), which must be overcome when a fixed amount of energy is delivered. However, optimal peak currents for conversion of VF remain unclear. We aimed to determine the role of peak current and optimal peak levels for conversion in collapsed VF patients.</p><p><b>METHODS</b>Adult, non-pregnant patients presenting with non-traumatic VF were included in the study. All defibrillations that occurred were included. Impedance values during defibrillation were used to calculate peak current values. The endpoint was return of spontaneous circulation (ROSC).</p><p><b>RESULTS</b>Of the 197 patients analysed, 105 had ROSC. Characteristics of patients with and without ROSC were comparable. Short duration of collapse < 10 minutes correlated positively with ROSC. Generally, patients with average or high TTI converted at lower peak currents. 25% of patients with high TTI converted at 13.3 ± 2.3 A, 22.7% with average TTI at 18.2 ± 2.5 A and 18.6% with low TTI at 27.0 ± 4.7 A (p = 0.729). Highest peak current conversions were at < 15 A and 15-20 A. Of the 44 patients who achieved first-shock ROSC, 33 (75.0%) received < 20 A peak current vs. > 20 A for the remaining 11 (25%) patients (p = 0.002).</p><p><b>CONCLUSION</b>For best effect, priming biphasic defibrillators to deliver specific peak currents should be considered.</p>

Effect of transthoracic impedance on defibrillation efficacy and safety in a porcine model / 中华急诊医学杂志

Objective Two different transthoracic impedances were made with an adjustable impedance instrument to compare the success rate of defibrillation,heart and skin damage in a porcine model.Methods A total of sixteen pigs were randomly (random number) divided into two groups:low impedance group (about 50 Ω,n =8) and high impedance group (about 100 Ω,n =8).Defibrillation (recommended 150 J) was first attempted at 15 s after induction of ventricular fibrillation (VF).If spontaneous circulation was not recovered,2-minute chest compression and subsequent defibrillation attempts (maximum 200 J) were attempted.Model animal kept stabilization for 30 min after return of spontaneous circulation before induction of the next episode of VF,which was induced five episodes in each pig.Results In the low impedance group,VF was induced 39 times,39 of 43 attempted defibrillations were successful.In the high impedance group,VF was induced 40 times,40 of 70 attempted defibrillations were successful.The current and success rate of the first defibrillation were (34.9 ±3.2) A and 94.9％ respectively in the low impedance group,while those of the high impedance group were (19.1 ±2.1) A and 50％ respectively (both P ＜ 0.05).There were no significant differences in skin damage between two groups,but myocardial injury was lighter in the high impedance group.Conclusions Success rate of the first defibrillation with recommend 150 J obviously decreases with the increase of transthoracic impedance.The main factor of myocardial injury is current instead of the numbers of defibrillation.

La cardioversión eléctrica en fibrilación auricular / Electrical cardioversion in atrial fibrillation

La cardioversión eléctrica para el tratamiento de la fibrilación auricular (FA) se introdujo en la década de los 60 y se mantiene actualmente como el tratamiento más efectivo y seguro para la conversión a ritmo sinusal. El método óptimo para la cardioversión eléctrica de la FA incluye tanto la selección del paciente adecuado como una técnica de cardioversión eléctrica apropiada. Los factores que han sido implicados en el éxito de la cardioversión eléctrica transtorácica incluyen aquéllos relacionados con: 1) la presencia de cardiopatía; 2) el habitus corporal del paciente; 3) la energía proporcionada; 4) la forma de onda eléctrica proporcionada, y 5) misceláneas. En vista de las consecuencias hemodinámicas y tromboembólicas, la conversión a ritmo sinusal puede esperarse que reduzca o suprima los síntomas y morbimortalidad asociadas con la FA. El éxito de la cardioversión eléctrica es alto de acuerdo al paciente seleccionado y la frecuencia de recurrencia inmediata o tardía postcardioversión puede ser alta y se requiere el uso de antiarrítmicos especialmente en presencia de comorbilidad como insuficiencia cardiaca o hipertensión descontrolada. El objetivo del tratamiento antiarrítmico concomitante es aumentar la posibilidad de éxito y prevenir las recurrencias, el cual debe considerarse de manera individual tomando en cuenta sobre todo el tiempo de evolución de la FA y la presencia y severidad de la cardiopatía. La posibilidad de cardioversión eléctrica exitosa en más probable en FA de corta duración y ausencia de cardiopatía.

Electrical cardioversion for treatment of atrial fibrillation (AF) was introduced in the early 1960s and remains today as the most effective and safe treatment for conversion to sinus rhythm. The optimal method for electrical cardioversion of AF includes appropriate patient selection as well as an appropriate electrical cardioversion technique. Factors that have been implicated in the success of transthoracic electrical cardioversion include those associated with: 1) the presence of heart disease; 2) the patient body habitus; 3) the energy applied; 4) the electrical waveform supplied and 5) miscellaneous. In view of the hemodynamic and thromboembolic consequences, conversion to sinus rhythm can be expected to reduce or abolish symptoms and morbidity associated with AF. The success of electrical cardioversion is high according to selected patient and the frequency of immediate or delayed recurrence post-cardioversion may be high and require the use of antiarrhythmics, especially in the presence of co-morbidities like heart failure or uncontrolled hypertension. The objective of concomitant antiarrhythmic therapy is to increase the likelihood of success and prevent recurrences, which must be considered individually taking into account especially the duration of AF and the presence and severity of heart disease. The possibility of successful electrical cardioversion is more likely in AF of short duration and absence of heart disease.

Doble choque eléctrico secuencial transtorácico para la fibrilación auricular refractaria / Double sequential electrical transthoracic shocks for refractory atrial fibrillation

Antecedentes: Estudios clínicos han mostrado que el éxito de la cardioversión transtorácica en fibrilación auricular depende de alcanzar un flujo de corriente adecuado al corazón y que es dependiente de la impedancia transtorácica. Cuando múltiples cardioversiones convencionales fallan para restaurar el ritmo sinusal en pacientes con fibrilación auricular el doble choque secuencial transtorácico puede ser una alternativa. Métodos y resultados: 21 pacientes consecutivos con fibrilación auricular paroxística o persistente refractaria al menos a dos choques monofásicos con energía inicial alta 360 J ó 200-300 y 360 J recibieron choques secuenciales con 720 J mediante dos desfibriladores. Edad media 64 ± 11 años y peso medio 97 ± 19 kg (intervalos, 49 a 112). La evolución de la fibrilación auricular fue < 3 meses en el 76%. La hipertensión presente en 38% y ausencia de cardiopatía en 33%. El tamaño medio de la aurícula izquierda fue 4.5 ± 0.7 cm (intervalos, 3.5 a 6.0). El ritmo sinusal se alcanzó en 19 (90.4%), incluyendo 2 casos refractarios a choques bifásicos con una mediana de 1,050 J (intervalos, 660 a 1,440 J) sin complicaciones mayores. El análisis multivariable identificó a la duración de la fibrilación auricular, > 90 días (RR 0.98, IC 0.95-0.98 p = 0.02) y al peso corporal, 101 ± 11 kg (RR 0.64, IC 0.46-0.90 p = 0.01) como variables independientes asociadas con el fracaso de la cardioversión. El peso corporal, p = 0.002 fue el predictor univariable de cardioversión no exitosa. La cardioversión de alta energía no causa daño miocárdico evidenciado por estimación con troponina T. Conclusión: Para la fibrilación auricular refractaria a la cardioversión eléctrica convencional el doble choque secuencial transtorásico representa una alternativa segura y altamente eficaz y puede tener una aplicabilidad general.

Background: Clinical studies have shown that transthoracic cardioversión of atrial fibrillation is dependent on achieving adequate current flow to the heart, which is dependent on transthoracic impedance. When multiple standard cardioversión fails to restore sinus rhythm in patients with atrial fibrillation the double sequential transthoracic shock may be an alternative. Methods and results: Twenty one consecutive patients with paroxysmal or persistent atrial fibrillation refractory to at least two initial high energy 360 J or 200-300 and 360 J monophasic shocks underwent double sequential shocks with 720 J by means two defibrillators. Mean age was 64 ± 11 years and mean weight 97 ± 19 kg (range, 49 to 112). Duration of atrial fibrillation was present < 3 months in 76%. Arterial hypertension was present in 38% and lone atrial fibrillation in 33%. Mean left atrial size was 4.5 ± 0.7 cm (range, 3.5 to 6.0). Sinus rhythm was achieved in 19 (90.4%). Two refractory to biphasic shocks with a median 1,050 J (range, 660 to 1,440 J) without major complications. Multivariate analysis identified duration of atrial fibrillation, > 90 days (RR 0.96, Cl 0.95-0.98 p = 0.02) and body weight, 101 ± 11 kg (RR 0.64, Cl 0.46-0.90 p = 0.01) variables independently associated with cardioversión unsuccessful. Patient weight, p = 0.002 was the univariate predictor of unsuccessful cardioversión. High energy cardioversión does not cause cardiac damage evidenced from cardiac troponin T estimation. Conclusion: For refractory atrial fibrillation to conventional cardioversión double sequential transthoracic shocks represents a safe and highly efficacious alternative and may have a general applicability.