Objectives: Longstanding pulmonary regurgitation(PR) leads to progressive RV volume overload and dysfunction after repair of tetralogy of Fallot(TOF). Although it was suggested that some associated factors have an effect on this mechanics, the influences of pressure load have not been evaluated. The aim of our study was to determine whether RV mechanics differ in patients with PR and pressure load compared with those without pressure load.
Methods: From June, 2004 to December, 2007, 202 cardiac magnetic resonance imaging(CMR) was performed in 185 patients after repair of TOF to assess the RV volume, function, and the degree of PR, The CMR data were analyzed and RV end-diastolic volume(EDV), end-systolic volume(ESV), ejection fraction(EF), and fraction of PR(PR%) were measured. Patients in whom echocardiography demonstrated significant RV outflow obstruction(Doppler gradient ≥30mmHg) and RV pressure overload(estimated RV pressure by tricuspid regurgitation jet velocity ≥50mmHg) were defined as PR with PS groups(n=50), and compared with the patient without obstruction(PR group, n=88). Patients with significant tricuspid regurgitation and/or residual intracardiac shunts were excluded.
Results:Although PR% was not different between two groups(42.6 ± 11.5% in PR group, 40.8 ± 10.0% in PR with PS group, P=0.3), PR with PS group showed a significantly smaller RVEDV index(136.7 ± 26.5 mL/m2, 151.2 ± 34.7mL/m2, P=0.01) and RVESV index(68.1 ± 23.7mL/m2, 80.2 ± 27.5mL/m2, P=0.01) than PR group. In correlation study, RV estimated pressure showed significant inverse correlation with PR% in PR with PS group(r=-0.43, P=0.002). However in PR group, RV estimated pressure was not correlated with PR% and RVEF.
Conclusions : After repair of TOF, patients with pressure load tended to less RV enlargement inspite of severe PR. Proper residual RVOT obstruction has not adverse effects on RV volume overload from PR. It is suggested that proper relief of RVOT obstruction with acceptable residual stenosis has more advantage than aggressive RVOT enlargement in longterm outcome of these patients.
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