Eccentric Enlargement of the Aortic Sinuses in Pediatric and Adult Patients with Bicuspid Aortic Valves: A Cardiac MRI Study.

Aortic root size and cusp fusion pattern have been related to disease outcomes in bicuspid aortic valve (BAV). This study seeks to characterize symmetry of the aortic sinuses in adult and pediatric BAV patients and its relationship to valvulopathy and root aortopathy. Aortic sinus-to-commissure (S-C) lengths were measured on cardiac MRI of adult and pediatric BAV patients with right-and-left coronary (RL) or right-and-non-coronary (RN) leaflet fusion and tricuspid aortic valve (TAV) controls. Coefficient of variance (CoV) of S-C lengths was calculated to quantify sinus asymmetry, or eccentricity. BAV cohort included 149 adults (48 ± 15 years) and 51 children (15 ± 5 years). TAV cohort included 40 adults (60 ± 13 years) and 20 children (15 ± 5 years). In adult and pediatric BAV patients, the non-fused aortic sinus was larger than either fused sinus. In RL fusion, the non-coronary S-C distance was larger than right or left S-C distances in adults (n = 121, p < 0.001) and larger than the right S-C distance in children (n = 41, p = 0.013). Sinus eccentricity (CoV) in BAV patients was higher than in TAV patients (p < 0.001) and did not correlate with age (p = 0.12). CoV trended higher in RL adults with aortic regurgitation (AR) compared to those without AR (p = 0.081), but was lower in RN adults with AR than without AR (p = 0.006). CoV did not correlate to root Z scores (p = 0.06-0.55) or ascending aortic (AAo) Z scores in adults (p = 0.45-0.55) but correlated negatively to AAo Z score in children (p = 0.005-0.03). Most adult and pediatric BAV patients with RL and RN leaflet fusion demonstrate eccentric dominance of the non-fused aortic sinus irrespective of age. The degree of eccentricity varies with valve dysfunction and BAV phenotype but does not relate to the degree of aortic root dilatation, nor does eccentricity correlate with ascending aorta dilatation in adults.

MR angiography and 2-D phase-contrast imaging for evaluation of meso-rex bypass function.

BACKGROUND: The meso-Rex bypass restores blood flow to the liver in patients with extrahepatic portal vein thrombosis. Stenosis occurs in some cases, causing the reappearance of portal hypertension. Complications such as thrombocytopenia present on a spectrum and there are currently no guidelines regarding a threshold for endovascular intervention. While Doppler ultrasound (US) is common for routine evaluation, magnetic resonance (MR) angiography with two-dimensional phase-contrast MRI (2-D PC-MRI) may improve the assessment of meso-Rex bypass function. OBJECTIVES: To determine the feasibility and utility of MR angiography with 2-D PC-MRI in evaluating children with meso-Rex bypass and to correlate meso-Rex bypass blood flow to markers of portal hypertension. MATERIALS AND METHODS: MR angiography and 2-D PC-MRI in meso-Rex bypass patients were retrospectively analyzed. Minimum bypass diameter was measured on MR angiography and used to calculate cross-sectional area. Meso-Rex bypass blood flow was measured using 2-D PC-MRI and divided by ascending aortic flow to quantify bypass flow relative to systemic circulation. Platelet and white blood cell counts were recorded. Correlation was performed between minimum bypass area, blood flow and clinical data. RESULTS: Twenty-five children (median age: 9.5 years) with meso-Rex bypass underwent MR angiography and 2-D PC-MRI. The majority of patients were referred to imaging given clinical concern for complications. Eighteen of the 25 patients demonstrated >50% narrowing of the bypass cross-sectional area. The mean platelet count in 19 patients was 127 K/µL. There was a significant correlation between minimum cross-sectional bypass area and bypass flow (rho=0.469, P=0.018) and between bypass flow and platelet counts (r=0.525, P=0.021). CONCLUSION: Two-dimensional PC-MRI can quantify meso-Rex bypass blood flow relative to total systemic flow. In a cohort of 25 children, bypass flow correlated to minimum bypass area and platelet count. Two-dimensional PC-MRI may be valuable alongside MR angiography to assess bypass integrity.

Comprehensive MR Analysis of Cardiac Function, Aortic Hemodynamics and Left Ventricular Strain in Pediatric Cohort with Isolated Bicuspid Aortic Valve.

Bicuspid aortic valve (BAV) disease demonstrates a range of clinical presentations and complications. We aim to use cardiac MRI (CMR) to evaluate left ventricular (LV) parameters, myocardial strain and aortic hemodynamics in pediatric BAV patients with and without aortic stenosis (AS) or regurgitation (AR) compared to tricuspid aortic valve (TAV) controls. We identified 58 pediatric BAV patients without additional cardiovascular pathology and 25 healthy TAV controls (15.3 ± 2.2 years) who underwent CMR with 4D flow. BAV cohort included subgroups with no valvulopathy (n = 13, 14.3 ± 4.7 years), isolated AS (n = 19, 14.5 ± 4.0 years), mixed valve disease (AS + AR) (n = 13, 17.1 ± 3.2 years), and prior valvotomy/valvuloplasty (n = 13, 13.9 ± 3.2 years). CMR data included LV volumetric and mass indices, myocardial strain and aortic hemodynamics. BAV patients with no valvulopathy or isolated AS had similar LV parameters to controls excepting cardiac output (p < 0.05). AS + AR and post-surgical patients had abnormal LV volumetric and mass indices (p < 0.01). Post-surgical patients had decreased global longitudinal strain (p = 0.02); other subgroups had comparable strain to controls. Patients with valvulopathy demonstrated elevated velocity and wall shear stress (WSS) in the ascending aorta (AAo) and arch (p < 0.01), while those without valve dysfunction had only elevated AAo velocity (p = 0.03). Across the cohort, elevated AAo velocity and WSS correlated to higher LV mass (p < 0.01), and abnormal hemodynamics correlated to decreased strain rates (p < 0.045). Pediatric BAV patients demonstrate abnormalities in LV parameters as a function of valvular dysfunction, most significantly in children with AS + AR or prior valvotomy/valvuloplasty. Correlations between aortic hemodynamics, LV mass and strain suggest valvular dysfunction could drive LV remodeling. Multiparametric CMR assessment in pediatric BAV may help stratify risk for cardiac remodeling and dysfunction.