Purpose: Atrioventricular valve regurgitation is a known risk factor for adverse outcomes in patients who undergo Fontan palliation. However, the mechanism of atrioventricular valve regurgitation development has not been clarified in these patients. We aimed to assess the relationship between atrioventricular valve regurgitation and annulus morphology and examine the mechanism of atrioventricular valve regurgitation in Fontan palliation.

Patients and Methods: A total of 102 patients who underwent Fontan palliation and three-dimensional transthoracic echocardiography were retrospectively evaluated. The dataset of the atrioventricular valve obtained by three-dimensional transthoracic echocardiography and the following parameters were measured to characterize the three-dimensional geometry of the atrioventricular valve annulus: annulus area, annulus height, and bending angle. The atrioventricular valve was classified into the following five groups: common atrioventricular valve, single tricuspid valve, single mitral valve, tricuspid valve in two separate valves, and mitral valve in two separate valves. The atrioventricular valve annulus parameters were compared between the five groups. The atrioventricular valve regurgitation severity was assessed by the vena contracta width, and its relationship with the atrioventricular valve annulus parameters was evaluated.

Results and Discussion: Atrioventricular valve morphology was the common atrioventricular valve in 33 patients, single tricuspid valve in 22 patients, single mitral valve in 32 patients, and two separate valves in 15 patients. The common atrioventricular and single tricuspid valves had a larger annulus area, smaller height, and larger bending angle than the other atrioventricular valve morphologies. The frequency of greater than or equal to moderate atrioventricular valve regurgitation was higher in patients with the common atrioventricular and single tricuspid valves. In the common atrioventricular and single tricuspid valves, vena contracta width correlated with annulus area, and functional single ventricular size. The annulus area was an independent determinant of vena contracta width after adjustment for functional single ventricular size.

Conclusion: Atrioventricular valve regurgitation was observed significantly more frequently in patients with the common atrioventricular and single tricuspid valves than with the other atrioventricular valve morphologies after Fontan palliation. The increased annulus area and functional single ventricular size are suggested to be important features in the mechanism of atrioventricular valve regurgitation.

Purpose: Sonographic measurements of the inferior vena cava parameters are common noninvasive methods for estimating the right atrial pressure. In intermediate cases in which the inferior vena cava parameters showed an indeterminate value, the current guidelines of the American Society of Echocardiography recommended using the secondary indices, which include the restrictive right-sided diastolic filling pattern, ratio of early-diastolic transtricuspid flow velocity to tricuspid annular velocity, and hepatic venous systolic filling fraction. We aimed to clarify whether the aforementioned secondary indices improve the diagnostic ability of an elevated right atrial pressure using the inferior vena cava parameters and test the incremental predictive value of the right atrial area measurement.

Patients and Methods: In 128 consecutive patients with various cardiac diseases referred for cardiac catheterization, the elevated right atrial pressure was defined as ≥ 8 mmHg. Based on the inferior vena cava morphology, the estimated right atrial pressures were determined as 3, 8, and 15 mmHg (model 1). Additionally, the restrictive filling pattern, ratio of early-diastolic transtricuspid flow velocity to tricuspid annular velocity, and systolic filling fraction were evaluated to reclassify the intermediate value of 8 mmHg (model 2). The right atrial minimum and maximum areas and volumes were measured at the ventricular end diastole and systole, respectively, and the expansion indices were calculated.

Results: An elevated right atrial pressure was observed in 29 patients. Logistic regression analysis showed that the estimated right atrial pressure based on the inferior vena cava indices and systolic filling fraction were significantly associated with an elevated right atrial pressure (p < 0.05). The restrictive filling pattern was not observed in any of the patients, and the ratio of early-diastolic transtricuspid flow velocity to tricuspid annular velocity was not associated with an elevated right atrial pressure. The right atrial morphological and functional parameters were significantly associated with an elevated right atrial pressure (p < 0.05). Notably, the minimum right atrial area demonstrated the strongest association with the right atrial pressure elevation (odds ratio adjusted for right ventricular systolic function, 10.64; p < 0.01). The predictive ability of model 2 was comparable with that of model 1 (global χ² values, 9 and 11 for models 1 and 2, respectively; p =  0.28). In contrast, incorporated with the systolic filling fraction and minimal right atrial area as the secondary indices, the predictive ability of the new model was improved compared with that of model 1 (global χ² values, 9 and 25 for model 1 and the new model, respectively; p < 0.01).

Conclusion: Reclassification using the guideline-recommended secondary indices failed to improve the predictive ability of an elevated right atrial pressure. In contrast, a combination of the systolic filling fraction and minimal right atrial area with the inferior vena cava indices improved the predictive ability of an elevated right atrial pressure.