Background: The aim of this study was to identify non-invasively the potential impact of pulmonary regurgitation and age at surgical repair on the right ventricular (RV) textural and functional myocardial properties in patients operated on for tetralogy of Fallot (TOF).
Methods: We assessed the average intensity (Int.(1B)) and the cyclic variation (CV(IB)) of the echocardiographic backscatter curve in 30 TOF patients (mean age 16.2 +/- 8.3 years), who had undergone corrective surgery (mean age at repair 3.2 +/- 2.6 years, range 0.2-11 years). They were divided into three age- and body surface area (BSA)-matched subgroups according to the results of the surgical repair: 12 patients had no significant postsurgical sequelae (group I), 12 patients had isolated moderate-severe pulmonary regurgitation (group II), and 6 patients had pulmonary regurgitation associated with significant (> 30 mmHg) RV outflow tract obstruction (group III). In addition, 30 age-, sex- and BSA-matched normal subjects were identified as the control group.
Results: In our study population, CV(IB) was lower (7.86 +/- 2.5 vs 10.6 +/- 1.4 dB, p < 0.001) and Int.IB higher (-18.6 +/- 4.1 vs -21 +/- 2.8 dB, p = 0.01) compared to the control group. Comparison between the control group and each subgroup of TOF patients showed: a) comparable values of CV(IB) and Int.(IB) in group I (10.6 +/- 1.4 vs 9.4 +/- 2.3 dB, p = 0.07; and -21 +/- 2.8 vs -21.4 +/- 2.3 dB, p = 0.7, respectively); b) Int.(IB) was significantly different only in group III (-21 +/- 2.8 vs -13.3 +/- 4.6 dB, p < 0.0001), c) CV(IB) was different either in group II or III (10.6 +/- 1.4 vs 7.42 +/- 2, p < 0.001; and 10.6 +/- 1.4 vs 5.56 +/- 1.8, p < 0.001, respectively). In addition, comparison of integrated backscatter indexes among the TOF subgroups revealed significant differences of CV(IB) between group I and II (9.4 +/- 2.4 vs 7.4 +/- 2, p = 0.03) and between group I and III (9.4 +/- 2.4 vs 5.56 +/- 1.8, p = 0.004), and of Int.(IB) between group I and III (-21.4 +/- 2.3 vs -13.3 +/- 4.66, p < 0.001) and between group II and III (-21.4 +/- 2.3 vs -18.6 +/- 2.8, p = 0.006). Group III patients, who had the most significant RV dilation, expressed as the ratio between RV and left ventricular end-diastolic diameter (0.55 +/- 0.8) compared to group II (0.67 +/- 0.11, p = 0.038) and group I (0.55 +/- 0.87, p < 0.001), showed the lowest values of CV(IB) (5.56 +/- 1.8 dB) and the highest values of Int.(IB) (-13.3 +/- 4.6 dB) Finally, in our study population, both the degree of RV dilation and the age at surgical repair significantly correlated with Int.(IB) (r = 0.49 and r = 0.4, p = 0.06 and p = 0.033, respectively) and inversely correlated with CV(IB) (r = -0.55 and r = -0.53, p = 0.002 and p = 0.003, respectively).
Conclusions: In patients operated on for TOF: a) integrated backscatter analysis may identify patients with significant RV myocardial abnormalities related to postsurgical sequelae; b) residual pulmonary regurgitation, particularly if associated with pulmonary stenosis, appears to affect RV myocardial properties; c) an earlier repair of TOF may result in better preservation of myocardial characteristics.