RESUMO
Las frecuencias anormalmente rápidas sobre un corazón con una estructura menos distensible, rodeado por una coraza que sólo le permite defenderse con la frecuencia cardiaca para sostener el gasto cardiaco, hacen que este sea un corazón con márgenes estrechos de tolerancia frente a las taquiarritmias. Las frecuencias persistentes y superiores a 220 latidos por minuto, generan presiones anormalmente altas sobre todo el corazón y el sistema venoso. Hidrops y edema placentario son secuelas finales antes de la muerte fetal, y aún hasta este punto se pueden controlar y revertir. Aunque en teoría cualquier tipo de arritmias común en la vida extrauterina se podría desencadenar en el feto, 90% de éstas están incluidas en la taquicardia supraventricular reciprocante y en el flutter. Ambos tipos de arritmias pueden responder a la digoxina, aunque algunas son refractarias a este medicamento. La aplicación de ultrasonido sobre el corazón, permite no sólo descartar anomalías cardiacas asociadas, sino realizar protocolos de tratamiento. La medición de la relación de los tiempos ventrículo atrial:atrio ventricular, permite considerar otro tipo de arritmias como la taquicardia ectópica de la unión y la forma permanente reciprocante de la unión, etc., e incluir otros anti-arrítmicos, como amiodarona, flecainida, sotalol, entre otros. La principal vía de uso de los anti-arrítmicos es la transplacentaria. Por lo tanto, no sólo el feto se expone a posibles efectos secundarios, sino también la madre. Un grupo multidisciplinario enfrentará esta situación con el fin de ofrecer el mejor resultado para los dos.
A heart with a not much distensible structure, surrounded by a membrane, and only able to react with the heart rate for maintaining its cardiac output, has a narrow margin of tolerance in front of tachyarrhythmias. Persistent heart rates >200/min generate abnormally high pressure on the heart and the venous system. Hydrops and placental edema are common final outcomes before fetal death, that still at this point can be controlled and reverted. Although theoretically any type of arrhythmias could be developed in the fetus, 90% of fetal tachyarrhythmias correspond to supraventricular reciprocant tachycardia and flutter. Both types of arrhythmias may respond to digoxin, although some are refractory to this drug. Ultrasound application to the heart allows not only to rule out associated heart anomalies, but to realize treatment protocols. The measurement of the relation between ventricular-atrial and atrio-ventricular times allows to consider another type of arrhythmias such as junctional ectopic tachycardia, permanent junctional reprocicant tachycardia, etc., and to include other antiarrhythmics such as amiodarone, flecainide and sotalol among others. The main administration route of antiarrhythmics is the transplacental. Therefore not only the fetus but also the mother is exposed to drug side effects. A multidisciplinary group will confront this situation in order to offer both mother and fetus the best result.
Assuntos
Arritmias Cardíacas , Ecocardiografia , TaquicardiaRESUMO
OBJECTIVE: To review the diagnosis, treatment, and perinatal outcome of fetal tachyarrhythmias. METHODS: We reviewed the medical records of pregnant women diagnosed with fetal tachyarrhythmia at Asan Medical Center from June 1997 to December 2004. Tachyarrhythmias were classified as either supraventricular tachycardia (SVT) or atrial flutter (AF), and the intrauterine management and long-term outcomes of the infants were analyzed. RESULTS: There were three cases of SVT and four cases of AF. Fetal hydrops was noted in 4 of 7 fetuses and there were no cardiac anomalies. All of them were treated in utero with antiarrhythmic agents including digoxin and flecainide. During antiarrhythmic therapy, sinus rhythm was achieved in 100% of them and the survival rate was 100%. Two infants diagnosed prenatally with SVT developed Wolff-Parkinson-White syndrome after birth. One of them developed paroxysmal SVT but after adenosine treatment she needed no treatment. One fetus with AF was diagnosed with an atrial ectopic tachyarrhythmia postnatally which needed medication for one year and resulted in normal sinus rhythm. At the time of this study, all of them showed normal development without neurological morbidity. CONCLUSION: Fetal tachyarrhythmias diagnosed prenatally can be effectively treated with antiarrhythmic drugs in utero or postnatally even if they had hydropic feature. So they must be referred to a tertiary care center for appropriate counseling and management. We recommend that every SVT or AF should be treated in utero regardless of the presence of hydrops.