[Myocardial dysfunction secondary to persistent tachycardia]

Abstract

This study demonstrates the presence of variable degrees of reversible ventricular dysfunction in five patients with incessant atrioventricular tachycardia (IAVT) submitted to surgical ablation of the anomalous pathway. The patients were three females and two males, with age ranging from four to 39 years (mean 15.2). Preoperative EKG presented persistent tachycardia with narrow QRS and RP greater than PR in every case. The P wave was negative in leads D2, D3, AVF from V2 to V6. The 24 hours Holter monitoring demonstrated IAVT rhythm with few sinus beats. The heart rate variated from 140 to 190 bpm (mean 158 bpm). The echocardiogram ejection fraction ranged from 33% to 59% (mean 49.6%). The left ventricular diastolic diameter varied from 47 to 66 mm (mean 53.8). The chest X-ray showed moderate heart enlargement in two patients and mild enlargement in one. All the patients were refractory to isolated or associated antiarrhythmic drugs. Postero-septal anomalous A-V pathway (with exclusively slow retrograde conduction, was demonstrated by electrophysiologic study. After surgery every patient was asymptomatic without medication. Permanent sinus rhythm with heart rate of 62 to 100 bpm (mean 78.4 bpm) in a four months to two years follow-up. The postoperative echocardiogram ejection fraction ranged from 63% to 81% (mean 71.6%) and the left ventricular diastolic diameter was 42 to 57 mm (mean 48.2 mm). The heart area was normal in four patients and mildly increased in one patient. Thus, persistent increase in heart rate induces variable degrees of reversible myocardial dysfunction.