Disturbed atrioventricular electromechanical function long after mustard operation for transposition of great arteries: A potential contributing factor to atrial flutter

Objective: The objectives were to study atrial and ventricular electromecha nical function in patients long after Mustard repair for transposition of g reat arteries and to identify possible causes and physiologic disturbances in those with recurrent atrial flutter. Methods: Electromechanical atrial and ventricular function was assessed in 22 patients (11 women) aged 27 +/- 5 years, 10 to 29 (mean 24) years after initial Mustard operation with electrocardiography and echocardiography. Th e study subjects involved 12 patients with documented atrial flutter and th e remaining 10 without history of atrial arrhythmia served as controls. All patients were studied while in sinus rhythm. Results. There was no difference in age, gender, or age at original Mustard surgery between the 2 patient groups. The P wave and QRS duration were sig nificantly broader in patients compared with controls (128 +/- 14 ms vs 100 +/- 10 ms, P < .05 and 120 20 ins vs 93 6 ins, P < .01). Right ventricular end diastolic dimension was not different, whereas left ventricular fracti on shortening was less (20% +/- 10% vs 35% +/- 12%, P < .01) in the patient group. Left and septal total ventricular long axes amplitude were signific antly lower in patients compared with controls (1.4 +/- 0.4 cm vs 1.7 +/- 0 .3 cm, P < .05 and 0.6 +/- 0.2 cm vs 1.0 +/- 0.3 cm, P < .01). Right-sided total long axis excursion was equally reduced in the 2 groups (1.0 +/- 0.3 cm). Septal and right-sided but not left-sided 'a' wave was smaller in the patients (1.2 +/- 1 nun vs 3 +/- 1.2 mm, P < .001 and 1 +/- 1.3 min vs 3 +/ - 0.9 mm, P < .01). Right atrial electromechanical delay was significantly longer in patients with respect to controls (110 +/- 14 ins vs 84 +/- 25 in s, P < .001), but on the left there was no difference. The P wave duration correlated closely with right atrial electromechanical delay, r = 0.79, P < 003. Significant tricuspid regurgitation was found in 9 of 12 patients but none of the controls. Conclusion: Right ventricular dysfunction is present long after Mustard ope ration for transposition of great arteries whether flutter occurs. However, in patients with history of atrial flutter, evidence of left ventricular d ysfunction, significant tricuspid regurgitation, impaired right atrial elec trical and mechanical function, and reversed onset of atrial systole is als o present. The consistent association of the disturbed atrial and ventricul ar electromechanical behavior suggests a multifactorial etiology for atrial arrhythmia.