Seguimiento del paciente con cardiodesfibrilador automático implantable / Follow-up of the patient with automatic implantable cardioverter-defibrillator

RESUMEN Introducción: Los cardiodesfibriladores mejoran la supervivencia de los pacientes con riesgo de muerte súbita cardíaca. Existen escasos datos en nuestro país acerca de su eficacia en el seguimiento. Objetivo: Describir la evolución en el seguimiento de los pacientes con primoimplante de un cardiodesfibrilador automático. Método: Estudio ambispectivo, longitudinal, en 47 pacientes con primoimplante de un cardiodesfibrilador en el período septiembre de 2007 a diciembre de 2016, con cierre el 31 de diciembre de 2017. La probabilidad acumulada de supervivencia se estimó a través de las curvas de Kaplan-Meier. Resultados: La edad media fue de 57 ± 14,6 años, con predominio del sexo masculino (74,5%) y la indicación en prevención secundaria (83%). Presentaron terapias apropiadas el 57,4% de los pacientes, terapias inapropiadas un 23,4%, proarritmia del cardiodesfibrilador un 14,9% y tormenta arrítmica el 12,8% de los pacientes. Las terapias apropiadas se relacionaron con la fracción de eyección ≤ 35% (p=0,022) y la edad (p=0,031). La supervivencia acumulada libre del primer evento a los cuatro años fue 34,7%. La mortalidad cardiovascular se relacionó con: existencia de cardiopatía estructural (p=0,044), fracción de eyección ≤ 35% (p<0,001), clase funcional III-IV (p=0,046), terapias apropiadas (p=0,014) y tormenta arrítmica (p=0,002). La supervivencia acumulada libre de mortalidad cardiovascular fue de 70,7% al cuarto año. Conclusiones: La supervivencia de los pacientes con cardiodesfibrilador es buena. La mortalidad se asocia a un mayor deterioro del estado cardiovascular y a las terapias del dispositivo.

ABSTRACT Introduction: Implantable cardioverter-defibrillators improve the survival of patients at risk of sudden cardiac death. There is relatively little data in our country about their follow-up effectiveness. Objective: To describe the outcome of patients with primo-implantation of an automatic cardioverter-defibrillator during follow-up. Methods: An ambispective longitudinal cohort study was conducted in 47 patients with primo-implantation of a cardioverter-defibrillator in the period September 2007 to December 2016, ending on December 31, 2017. The cumulative probability of survival was estimated through the Kaplan-Meier curves. Results: Mean age was 57 ± 14.6 years, with male predominance (74.5%) and indication in secondary prevention (83%). Adequate therapies were found in 57.4% of patients, inadequate therapies in 23.4%, implantable cardioverter-defibrillator proarrhythmia in 14.9% and arrhythmic storm in 12.8% of patients. Adequate therapies were related to an ejection fraction ≤ 35% (p=0.022) and age (p=0.031). Cumulative free survival from the first event at four years was 34,7%. Cardiovascular mortality was related to: existence of structural heart disease (p=0.044), ejection fraction ≤ 35% (p<0.001), functional class III-IV (p=0.046), adequate therapies (p=0.014) and arrhythmic storm (p=0.002). Cumulative free survival of cardiovascular mortality was 70.7% at the fourth year. Conclusions: The survival of patients with implantable cardioverter-defibrillator is satisfactory. Mortality is associated with further deterioration of cardiovascular status and with device therapies.

Effect of Ivabradine Prolonging the Cardiac Action Potential Duration With its Proarrhythmic Action in Experimental Rabbitin vitro / 中国循环杂志

Objective: To observe the effect of ivabradine (IVA) on atrial and ventricular monophasic action potential duration (MAPD) and its proarrhythmic action at presence of sea anemone toxin-II (ATX-II) in isolated rabbit heart modelin vitro. Methods: The perfusion of isolated heart from female New Zealand white rabbit was conducted by Langendorff method in vitro. Left atrial and left ventricular endo- , epi-cardial action potential were recorded when pacing with ifxed frequency of 350 ms (in correspondence with the heart rate of 171 times/min) to observe the effect of IVA alone and ATX-II (3 nmol/L) with IVA on MAPD90. In addition, to observe the action of IVA alone and ATX-II with IVA on proarrhythmia when IVA reducing the heart rate to autonomous cardiac rhythm as (156±10) times/min. Results: IVA at (3-10) μmol/L prolonged atrial and ventricular endo- , epi-cardial MAPD90 by (15.9 ± 2.0) ms, (31.5 ± 4.0) ms and (23.9 ± 3.0) ms (n=6,P<0.01), respectively. ATX-II at 3 nmol/L prolonged atrial and ventricular MAPD90 by (36.5 ± 5.0)ms and (19.9 ± 3.0) ms, (19.5 ± 4.0) ms (n=6,P<0.01) respectively. With ATX-II treatment, IVA at (6-10) μmol/L decreased atrial MAPD90 by (14.4 ± 4.0) ms (n=6,P<0.01), it induced atrial arrhythmia. With 3 nmol/L of ATX-II treated ventricle, IVA at (3-10) μmol/L obviously prolonged endo- and epi-cardial MAPD90 by (36.2 ± 7.0) ms and (27.5 ± 5.0) ms(n=6,P<0.01), respectively. IVA didn’t increase ventricular beat-to-beat variability and transmural dispersion of MAPD90 no matter with or without ATX-II treatment, no ventricular arrhythmia occurred. Conclusion: IVA prolongs both atrial and ventricular MAPD, with increased late sodium current, IVA may induce atrial arrhythmia but not ventricular arrhythmia in experimental rabbits in vitro.

Pro-fibrillatory Effects of KATP Channel Opener and the Action Potential Duration Restitution Kinetics in Isolated Swine Right Ventricle

BACKGROUND AND OBJECTIVES: It remains to be defined how K[ATP] Channel Opener facilitates to induce ventricular arrhythmias. The purposes of this study are to assess the effects of K[ARP] Channel Opener, PCO400, on the action potential duration (APD) and APD restitution (APDR) kinetics, and their relationship with induction of ventricular tachycardia (VT)/fibrillation (VF), pro-fibrillatory effects. MATERALS AND METHODS: We recorded transmembrane potentials (TMPs) by microelectrode technique to explore the effects of PCO400 in ninetecn isolated perfused swine right ventricles. TMPs were recorded on the endoeardial side at the concentrations 0 micrometer, 1 micrometer, 2.5 micrometer, 5 micrometer, 10 micrometer, and washed-out period (1 hour). Ventricular refractory periods were measured while scanning djastole with premature ventricular beats during pacing at the cycle length of 600 ms at each concentration. The maximal slopes (Smax) of APDR were calculated with the data of S1S2 pacing and VF. RESULTS: PCO400 reduced APD90 (208+/-76 ms to 41+/-9 ms during S1, p<0.001, 111+/-32 ms to 54+/-28 ms during VF, p<0.001). While PCO400 tended to increase Smax of APDR at the concentration of 1 micrometer (0.6 to 0.7 by S1S2, 2.3 to 3.0 during VF), it reduced Smax at higher concentrations (-0.01 by S1-S2, p<0.05;-1.1 during VF, p<0.01). The increment of PCO400 concentration was associated with facilitated VT/VF induction (24.4% to 100%, p<0.001). Spontaneous VF induction rate was the highest at 1 micrometer (38.5%) which resulted in the highest Smax. CONCLUSION: PCO400 shows pro-fibrillatory effect by APD reduction and dynamic changes of Smax, Smax is closely related to spontancous induction of VT/VF, and APD90 shortening below 70 ms is critical for the maintenance of VT/VF.