THE LONG QT SYNDROME WITH IMPAIRED ATRIOVENTRICULAR-CONDUCTION - A MALIGNANT VARIANT IN INFANTS

Introduction: The long QT syndrome (LQTS) is occasionally complicated by impaired AV conduction, mostly 2:1 AV block. This form of LQTS can manifest before birth or during neonatal life, and it is more sporadic than familial. It is usually an isolated disorder, although it can be accompanied by a variety of cardiovascular and other anomalies. In sp ite of different treatment modes, mortality is high. Methods and Resul ts: The reported case presented not only with 2:1 AV conduction, but a lso with Wenckebach episodes with impaired right and left bundle branc h conduction, and decremental conduction in the His-Purkinje axis, We also observed sinus pauses and accelerated AV junctional escape beats. Conclusion: Our findings, and similar observations by others, suggest involvement of the sinus node and the distal conduction system in thi s form of the LQTS. Several histologic studies have documented abnorma lities within the conduction system, including apoptosis. Because of t he rare occurrence and poor prognosis of the LQTS with impaired AV con duction, international guidelines for diagnosis and treatment are need ed. Development of an internal cardiac defibrillator for this young ag e group is necessary.