4D flow MRI of the aorta demonstrates age- and gender-related differences in aortic size and blood flow velocity in healthy subjects

Early Intraluminal Frozen Elephant Trunk Stent Graft Thrombosis After Aortic Arch Surgery

BACKGROUND

Partial intraluminal thrombosis of the frozen elephant trunk (FET) stent graft is a poorly described but not infrequent complication after aortic arch surgery. This study aims to describe and analyze the occurrence of early FET stent graft thrombosis.

METHODS

Retrospective single-center analysis including patients who underwent aortic arch replacement with FET technique between 2006 and 2020. Stent graft thrombosis was diagnosed through computed tomography scan. Several computed tomography scan parameters and clinical variables were analyzed as predictors of this event.

RESULTS

A total of 125 patients were included for analysis. Among these, 21 (16.8%) patients developed early postoperative FET stent graft thrombosis. Mean volumetric size of the aorta was 12.2 ± 2.0 mL in patients with FET stent graft thrombosis and 10.1 ± 2.8 mL in patients without thrombosis (P < .01). Thrombosis occurred more frequently among patients requiring thoracic endovascular aortic repair completion (15 of 21 [71.4%] patients) than in patients with completely excluded aneurysms (6 of 21 [28.6%] patients) (P = .01). Mean stent-to-aneurysm diameter ratio was 0.8 ± 0.2 among patients with thrombosis and 1.0 ± 0.2 among patients without thrombosis (P < .01). Thrombosis was more frequently observed among patients with conservative management of postoperative bleeding (P = .04). Patients with early FET thrombosis had a nonsignificantly higher in-hospital all-cause mortality than patients without thrombosis (19.0% vs 8.7%; P = .3).

CONCLUSIONS

Early postoperative intraluminal thrombosis is a frequent complication post FET surgery. Smaller stent graft sizes, larger or partially covered aneurysms, and major bleeding are associated with early thrombosis. Slight FET oversizing, prompt thoracic endovascular aortic repair completion, and early reintervention for major bleeding may prevent early thrombosis.

Population-based reference values for 4D flow MRI derived aortic blood flow parameters

Objective. This study assesses age-related differences of thoracic aorta blood flow profiles and provides age- and sex-specific reference values using 4D flow cardiovascular magnetic resonance (CMR) data.Approach. 126 volunteers (age 20-80 years, female 51%) underwent 4D flow CMR and 12 perpendicular analysis planes in the thoracic aorta were specified. For these planes the following parameters were evaluated: body surface area-adjusted aortic area (A'), normalized flow displacement (NFD), the degree of wall parallelism (WPD), the minimal relative cross-sectional area through which 80% of the volume flow passes (A80) and the angle between flow direction and centerline (α).Main results. Age-related differences in blood flow parameters were seen in the ascending aorta with higher values for NFD and angle and lower values for WPD and A80 in older subjects. All parameters describing blood flow patterns correlated with the cross-sectional area in the ascending aorta. No relevant sex-differences regarding blood flow profiles were found.Significance. These age- and sex-specific reference values for quantitative parameters describing blood flow within the aorta might help to study the clinical relevance of flow profiles in the future.