Right ventricular strain rate and strain analysis in patients with repaired tetralogy of Fallot: possible interventricular septal compensation.J Am Soc Echocardiogr. 2004 Apr; 17(4):338-44.JA
Indices such as strain rate (SR) and strain (epsilon) are free of geometric assumptions and, thus, may provide new insights into right ventricular (RV) function and compensatory mechanisms in repaired tetralogy of Fallot (TOF).
All those with postoperative (>1 year) TOF had echocardiography evaluation of SR and epsilon indices along the RV lateral free wall (RVFW) and the interventricular septum (IVS) in the apical 4-chamber view. Pulmonary regurgitation, pulmonary stenosis, QRS duration, RV ejection fraction, and RV dimension were also measured and compared with control subjects.
There were 15 patients with TOF (7 +/- 4 years old) 6 +/- 3 years remote from surgical repair and 25 control subjects (10 +/- 5 years old). In the patients with TOF, systolic and diastolic SR and epsilon in the RVFW were significantly reduced but were normal in the IVS. In the RVFW, reduced systolic SR and epsilon correlated with reduced RV ejection fraction (r = -0.7 [P <.01] and -0.6 [P <.03], respectively), and poorer early diastolic SR correlated with poorer RV ejection fraction (r = 0.7, P <.01).
In patients with postoperative TOF, systolic and diastolic RV SR and epsilon were impaired in the RVFW but preserved in the IVS. We speculate that IVS myocardial function is preserved as a compensatory mechanism for impaired RVFW function.