Right ventricular restrictive physiology in repaired tetralogy of Fallot is associated with smaller respiratory variability

Background: Long-term outcomes of patients with repaired tetralogy of Fallot (TOF) are known to be related with right ventricular (RV) volume overload, severity of pulmonary insufficiency (PI) and the type of outflow repair. Right ventricular restrictive physiology (RVRP) has also been reported to interfere with several factors influencing the late result in repaired TOF patients. However, the mechanism and physiology of this unique myocardial property in the chronically overloaded right ventricle are not yet clearly understood. Methods: We investigated 43 patients after repair of TOF to assess the relationships among biventricular diastolic function, volume characteristics, and influence of respiratory effort. The patients were classified into 3 groups; 15 patients with RVRP and significant PI (RP group, 35%), 19 without RVRP in the presence of significant PI (NR + PI group, 44%), and 9 without RP or significant PI (NR - PI group, 21%). Doppler spectrals obtained by echocardiography from systemic and pulmonary veins, main pulmonary artery (MPA), and both ventricular inlets, and biventricular diastolic function were compared according to the respiratory cycle. Results: The RP group revealed higher pulmonary venous systolic/diastolic flow ratio (S/D ratio) and the NR + PI group showed larger velocity-time integral (VTI) ratio of total regurgitant/antegrade flow at the MPA and more respiratory variability in the systemic vein. Conclusion: RP is associated with less volume overload of the RV and smaller respiratory variability is also associated with the restrictive RV. The diastolic function and volume status of the RV may influence the diastolic properties of the left heart.