RESUMEN
Hyperpolarization-activated cyclic nucleotide-gated channels (HCNs) are expressed in the ventricles of fetal hearts but are normally down-regulated as development progresses. In the hypertrophied heart, however, these channels are re-expressed and generate a hyperpolarization-activated, nonselective cation current (Ih), which evidence suggests may increase susceptibility to arrhythmia. To test this hypothesis, we generated and analyzed transgenic mice overexpressing HCN2 specifically in their hearts (HCN2-Tg). Under physiological conditions, HCN2-Tg mice exhibited no discernible abnormalities. After the application of isoproterenol (ISO), however, ECG recordings from HCN2-Tg mice showed intermittent atrioventricular dissociation followed by idioventricular rhythm. Consistent with this observation, 0.3 µmol/L ISO-induced spontaneous action potentials (SAPs) in 76% of HCN2-Tg ventricular myocytes. In the remaining 24%, ISO significantly depolarized the resting membrane potential (RMP), and the late repolarization phase of evoked action potentials (APs) was significantly longer than in WT myocytes. Analysis of membrane currents revealed that these differences are attributable to the Ih tail current. These findings suggest HCN2 channel activity reduces the repolarization reserve of the ventricular action potential and increases ectopic automaticity under pathological conditions such as excessive ß-adrenergic stimulation.
Asunto(s)
Expresión Génica , Ventrículos Cardíacos/metabolismo , Ventrículos Cardíacos/fisiopatología , Canales Regulados por Nucleótidos Cíclicos Activados por Hiperpolarización/genética , Miocitos Cardíacos/metabolismo , Ritmo Idioventricular Acelerado/inducido químicamente , Potenciales de Acción/efectos de los fármacos , Animales , Electrocardiografía , Ventrículos Cardíacos/citología , Ventrículos Cardíacos/efectos de los fármacos , Canales Regulados por Nucleótidos Cíclicos Activados por Hiperpolarización/metabolismo , Isoproterenol/farmacología , Ratones , Ratones Transgénicos , Miocitos Cardíacos/efectos de los fármacosRESUMEN
Aconite poisoning was examined in five patients (four males and one female) aged 49 to 78 years old. The electrocardiogram findings were as follows: ventricular tachycardia and ventricular fibrillation in case 1, premature ventricular contraction and accelerated idioventricular rhythm in case 2, AIVR in case 3, and nonsustained ventricular tachycardia in cases 4 and 5. The patient in case 1 was given percutaneous cardiopulmonary support because of unstable hemodynamics, whereas the other patients were treated with fluid replacement and antiarrhythmic agents. The main aconitine alkaloid in each patient had a half-life that ranged from 5.8 to 15.4 h over the five cases, and other detected alkaloids had half-lives similar to the half-life of the main alkaloid in each case. The half-life of the main alkaloid in case 1 was about twice as long as the half-lives in the other cases, and high values for the area under the blood concentration-time curve and the mean residence time were only observed in case 1. These results suggest that alkaloid toxicokinetics parameters may reflect the severity of toxic symptoms in aconite poisoning.
Asunto(s)
Aconitina/farmacocinética , Aconitum , Arritmias Cardíacas/inducido químicamente , Medicamentos Herbarios Chinos/farmacocinética , Ritmo Idioventricular Acelerado/inducido químicamente , Aconitina/análogos & derivados , Aconitina/sangre , Aconitina/envenenamiento , Aconitina/orina , Anciano , Área Bajo la Curva , Arritmias Cardíacas/fisiopatología , Biotransformación , Cromatografía Líquida de Alta Presión , Medicamentos Herbarios Chinos/envenenamiento , Electrocardiografía , Femenino , Semivida , Humanos , Masculino , Persona de Mediana Edad , Índice de Severidad de la Enfermedad , Taquicardia Ventricular/inducido químicamente , Espectrometría de Masas en Tándem , Toxicología/métodos , Fibrilación Ventricular/inducido químicamente , Complejos Prematuros Ventriculares/inducido químicamenteAsunto(s)
Ritmo Idioventricular Acelerado , Amiodarona , Taquicardia Ventricular , Ritmo Idioventricular Acelerado/inducido químicamente , Amiodarona/efectos adversos , Antiarrítmicos/efectos adversos , Electrocardiografía , Humanos , Taquicardia Ventricular/inducido químicamente , Fibrilación Ventricular/inducido químicamenteAsunto(s)
Ritmo Idioventricular Acelerado/veterinaria , Anestesia Intravenosa/veterinaria , Anestésicos Intravenosos/efectos adversos , Enfermedades de los Perros/cirugía , Propofol/efectos adversos , Procedimientos Quirúrgicos Refractivos/veterinaria , Ritmo Idioventricular Acelerado/inducido químicamente , Anestesia Intravenosa/efectos adversos , Animales , Enfermedades de los Perros/inducido químicamente , Enfermedades de los Perros/fisiopatología , Perros , Masculino , Procedimientos Quirúrgicos Refractivos/efectos adversosRESUMEN
We report the case of a 41-year-old ASA I patient who experienced during endometrial resection a transient idioventricular cardiac rhythm with hypotension related to a major glycine intoxication. The total volume of absorbed irrigating fluid was over six liters when these clinical signs occurred. The biological data were as following: Na = 89 mmol.L-1, Cl = 60 mmol.L-1 and osmolarity = 215 mOsm.L-1. Simultaneously, the glycine concentration in the plasma was 54.6 mmol.L-1, i.e 160 times higher than the normal value. The clinical course was unremarkable except vomiting. The treatment included only the administration of a diuretic agent, as the correction of the disorder took place spontaneously. The paucity of clinical symptoms when compared to the severity of the biological disorders explain why preventive measures are essential in this type of surgery.
Asunto(s)
Ritmo Idioventricular Acelerado/inducido químicamente , Endoscopía/efectos adversos , Glicina/envenenamiento , Histeroscopía/efectos adversos , Complicaciones Intraoperatorias , Adulto , Endometrio/cirugía , Femenino , Glicina/sangre , Humanos , Hiponatremia/etiología , Metrorragia/cirugíaRESUMEN
Accelerated idioventricular rhythm (AIVR) is a ventricular arrhythmia most commonly seen in adults with underlying cardiac disease. It is important to establish the diagnosis when it occurs to differentiate this benign phenomenon from dangerous ventricular tachycardia. We present the case of a healthy child who developed episodes of AIVR associated with propranolol treatment. Her 24-hour electrocardiography recording showed AIVR with difference between sinus and ventricular beats. The arrhythmia resolved with the discontinuation of propranolol, and eventually the case was in sinus rhythm. This patient is the first case of AIVR associated with propranolol treatment in the literature.
Asunto(s)
Ritmo Idioventricular Acelerado/inducido químicamente , Antagonistas Adrenérgicos beta/efectos adversos , Antiarrítmicos/efectos adversos , Propranolol/efectos adversos , Taquicardia Supraventricular/tratamiento farmacológico , Ritmo Idioventricular Acelerado/diagnóstico , Niño , Electrocardiografía , Femenino , Humanos , Taquicardia Supraventricular/diagnósticoAsunto(s)
Ritmo Idioventricular Acelerado/inducido químicamente , Antihipertensivos/efectos adversos , Glaucoma de Ángulo Abierto/tratamiento farmacológico , Sulfonamidas/efectos adversos , Tiofenos/efectos adversos , Timolol/efectos adversos , Ritmo Idioventricular Acelerado/diagnóstico , Combinación de Medicamentos , Electrocardiografía , Femenino , Humanos , Persona de Mediana Edad , Soluciones OftálmicasAsunto(s)
Ritmo Idioventricular Acelerado , Ritmo Idioventricular Acelerado/inducido químicamente , Ritmo Idioventricular Acelerado/fisiopatología , Ritmo Idioventricular Acelerado/terapia , Anciano de 80 o más Años , Antiarrítmicos/efectos adversos , Diagnóstico Diferencial , Electrocardiografía , Femenino , Humanos , Masculino , Guías de Práctica Clínica como AsuntoRESUMEN
We report a case of hypervagotonia manifested by idioventricular rhythm in a healthy, athletic man who participated in a Phase I study of an investigational calcium-channel blocker. Upon breaking the study's double-blind study code, it was discovered that the subject had received placebo. We discuss this unusual finding and the implications of including athletic subjects in safety/tolerance studies.