Right ventricular mechanics and QRS duration in patients with repaired tetralogy of Fallot: implications of infundibular disease.
BACKGROUND
Patients after repair of tetralogy of Fallot (ToF) frequently have right ventricular (RV) dysfunction and prolonged QRS duration (QRSd) and thus could be candidates for cardiac resynchronization therapy. We aimed to assess the relationship between QRSd and the timing of RV wall motion, including the RV outflow tract (RVOT), in these patients.


RESULTS
Sixty-seven repaired ToF patients (median age, 34 years; interquartile range, 24 to 43 years) and 35 age-matched control subjects were studied by echocardiography and cardiovascular magnetic resonance (n=55 of 67 ToF patients). Time intervals of the RV cardiac cycle were measured from Doppler recordings. Long-axis M-mode recordings were acquired from the right ventricular (RV) free wall and RV outflow tract (RVOT), and the delay in onset of long-axis shortening was measured. ToF patients showed minor abnormalities of the RV cardiac cycle unrelated to QRSd. RV ejection time was prolonged and correspondingly filling time was reduced compared with control subjects (22.3+/-2.6 versus 20.0+/-2.9 s/min, P<0.0001; 29.0+/-3.8 versus 32.7+/-3.5 s/min, P<0.0001). Total isovolumic time was normal in ToF patients (8.7+/-4.0 versus 7.4+/-2.9 s/min; P=NS). QRSd correlated with the delay in RV free wall motion (r=0.55, P<0.0001) and more so with the delay in RVOT shortening (r=0.82, P<0.0001). QRSd also correlated with measures of RVOT abnormality such as long-axis RVOT excursion and akinetic area length (r=-0.46, P=0.004; r=0.33, P=0.01).


CONCLUSIONS
QRSd in postoperative ToF patients reflects mainly abnormalities of the RVOT rather than the RV body itself. Thus, prevention and treatment of mechanical asynchrony and malignant arrhythmia should focus on the RV infundibulum. Indications for cardiac resynchronization therapy after ToF repair warrant further investigation.
Uebing
Anselm
A
Adult Congenital Heart Disease Centre, Royal Brompton Hospital, Sydney St, London SW3 6NP, UK.
Gibson
Derek G
DG
Babu-Narayan
Sonya V
SV
Diller
Gerhard P
GP
Dimopoulos
Konstantinos
K
Goktekin
Omer
O
Spence
Mark S
MS
Andersen
Kai
K
Henein
Michael Y
MY
Gatzoulis
Michael A
MA
Li
Wei
W
D000328:Adult; D002037:Bundle-Branch Block / Q000175:diagnosis* / Q000503:physiopathology* / Q000628:therapy; D002304:Cardiac Pacing, Artificial; D004452:Echocardiography / Q000592:standards; D004562:Electrocardiography; D006329:Heart Conduction System / Q000503:physiopathology / Q000601:surgery; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000592:standards; D009200:Myocardial Contraction; D011446:Prospective Studies; D015203:Reproducibility of Results; D013771:Tetralogy of Fallot / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000601:surgery; D016278:Ventricular Function, Right / Q000502:physiology*