Bases fisiológicas de la desfibrilación ventricular / Physiological bases of ventricular defibrillation

La desfibrilación ventricular es un procedimiento básico para una adecuada reanimación cardiopulmocerebral, pero sus principios no son comúnmente abordados en la literatura. Este trabajo tuvo como objetivo describir las bases fisiológicas de la desfibrilación ventricular para lo cual se realizó, en el primer cuatrimestre del 2018, una revisión documental que incluyó 21 referencias bibliográficas. Se concluyó que las bases fisiológicas integran a las funciones celulares propias del corazón, las modificaciones físico-moleculares celulares que condicionan la arritmia o se generan por la hipoxia, a los cambios que sobre el tejido cardiaco produce el paso de electricidad y a las características de la onda de choque eléctrica del desfibrilador. La desfibrilación detiene la actividad eléctrica cardiaca y permite el inicio de potenciales de acción de sus células marcapaso. La eficacia del procedimiento depende del estado metabólico del miocardio (dado por causa y tiempo de la parada cardiaca), y de la correcta realización del protocolo de desfibrilación.

Ventricular defribrillation is a basic procedure from an adequate cardio-pulmonary-cerebral resuscitation, but its principles are not commonly approached in literature. This work was aimed at describing the physiological basis of ventricular defibrillation for which it was, in the first quarter of 2018, a documentary review which included 21 bibliographical references. It was concluded that these bases integrate the cellular functions of the heart, the physical-molecular cellular modifications which condition arrythmia or are produced due to hypoxia, the changes on the cardiac tissue which allow the passage of electrical cardiac activity and the characteristics of the electrical shock wave of the defibrillator. Defibrillation stops cardiac electrical activity and allows the action potential start of its pacemaker cells.. The efficacy of the procedure depends on the metabolic condition of the myocardium (due to the cause and the time cardiac failure) and the correct performance of the defibrillation protocol.

Effect of single intraoperative dose of amiodarone in patients with rheumatic valvular heart disease and atrial fibrillation undergoing valve replacement surgery.

Maintenance of sinus rhythm (SR) is superior to rate control in atrial fibrillation (AF). In order to achieve SR, we administered single-dose intravenous amiodarone intraoperatively and evaluated its effect on conversion of rheumatic AF to SR in patients undergoing valvular heart surgery. Patients were randomly assigned to amiodarone (n = 42) or control (n = 40) group in a double blind manner. The amiodarone group received amiodarone (3 mg/kg) intravenously prior to the institution of cardiopulmonary bypass and the control group received the same volume of normal saline. In the amiodarone group, the initial rhythm after the release of aortic cross clamp was noted to be AF in 14.3% (n = 6) and remained so in 9.5% (n = 4) of patients till the end of surgery. In the control group, the rhythm soon after the release of aortic cross clamp was AF in 37.5% (n = 15) (p = 0.035) and remained so in 32.5% (n = 13) of patients till the end of surgery (p = 0.01). At the end of first post-operative day 21.4% (n = 9) of patients in amiodarone group and 55% (n = 22) of patients in control group were in AF (p = 0.002). The requirement of cardioversion/defibrillation was 1.5 (+/-0.54) in amiodarone group and 2.26 (+/-0.73) in the control group (p = 0.014), and the energy needed was 22.5 (+/-8.86) joules in the amiodarone group and 40.53 (+/-16.5) in the control group (p = 0.008). A single intraoperative dose of intravenous amiodarone increased the conversion rate of AF to normal sinus rhythm, reduced the need and energy required for cardioversion/defibrillation and reduced the recurrence of AF within one day.

Incidência de choques e qualidade de vida em jovens com cardioversor-desfibrilador implantável / Incidence of shock and quality of life in young patients with implantable cardioverter-defibrillator

OBJETIVOS: Avaliar a incidência e a causa de choques de CDI em crianças e adolescentes e sua repercussão na qualidade de vida (QV). MÉTODOS: De março/1997 a fevereiro/2006, 29 pacientes (15,7±5,4 anos) foram submetidos a implante de CDI. Parada cardiorrespiratória recuperada (41,5 por cento), taquicardia ventricular sustentada (27,6 por cento) e profilaxia primária de morte súbita cardíaca (30,9 por cento) motivaram os implantes. O número de terapias foi avaliado por entrevista e pela telemetria dos CDI. A QV foi avaliada pela aplicação do questionário SF-36 e comparada à de indivíduos saudáveis. Empregou-se o método de Kaplan-Meier para análise da sobrevida livre de choques. RESULTADOS: Após 2,6±1,8 anos de seguimento, 8 (27,6 por cento) pacientes receberam 141 choques apropriados em razão de TV polimórfica (6) ou FV (2), e 11 (37,9 por cento) sofreram 152 choques inapropriados em razão de taquiarritmias supraventriculares (8) ou oversensing (3). A expectativa de sobrevida livre de choques apropriados foi de 74,2 por cento±9,0 após um ano, e de 66,7 por cento±10,7 após três anos. Observou-se diminuição da QV nos aspectos físicos (61,7±28,7), na vitalidade (64,7±19,1), na saúde mental (65,9±22,7) e nos aspectos emocionais (66,7±38,5). Medo e preocupações relacionados ao CDI foram referidos por todos os pacientes. CONCLUSÃO: A despeito da grande eficácia dessa terapêutica, a incidência elevada de choques interferiu na QV e na adaptação ao dispositivo.

OBJECTIVES: To analyze the incidence and causes of ICD therapies in children and young adults and verify their impact on the quality of life (QoL). METHODS: From March/1977 to February/2006, 29 patients (15.7±5.4 years old) were submitted to ICD implants. Aborted cardiac arrest (41.5 percent), sustained ventricular tachycardia (27.6 percent) and primary prophylaxis of sudden cardiac death (30.9 percent) indicated device therapy. The number of therapies was evaluated by interviewing patients and by ICD diagnostic data. The SF-36 questionnaire was used to measure the QoL and the results were compared to healthy population. The expectative of freedom from ICD therapies were estimated by the Kaplan-Meier method. RESULTS: After 2.6±1.8 years follow-up, 8 (27.6 percent) patients received 141 appropriate ICD shocks due to ventricular tachycardia (6) or ventricular fibrillation (2), and 11 (37.9 percent) patients received 152 inappropriate ICD shocks due to supraventricular tachyarrhythmias (8) or oversensing (3). Expectative of freedom from appropriate shocks was 74.2±9.0 percent and 66.7±10.7 percent after one and three years, respectively. Compared to healthy population, QoL decreased in physical function (61.7±28.7), vitality (64.7±19.1), mental health (65.9±22.7) and role-emotional domains (66.7±38.5). All patients referred fear and concern related to ICD use. CONCLUSION: Despite the efficacy of ICD therapies, the high incidence of appropriate and inappropriate shocks interfered in patients' QoL and adaptation to the device.