Heartbeat-related distension and displacement of the thoracic aorta in healthy volunteers

Abstract

Purpose: To test our hypothesis that distension and displacement in various segments of the healthy thoracic aorta are significant and can be predicted based on clinical characteristics.

Materials and methods: Sixty-one Caucasian volunteers without cardiovascular disease (49 ± 16 years, range 19-82; 28 men, 33 women) divided into two age groups (A: <50, B: ≥ 50 years) underwent 1.5-T MRI. ECG-gated dynamic data sets were acquired at five locations perpendicular to the thoracic aorta. Aortic distension and Centre of Mass (CoM) displacement were determined as percentages of diastolic aortic diameter. A multiple linear regression model including age group, gender, location, mean arterial blood pressure, heart rate and body mass index was tested.

Results: Mean aortic distension averaged over all locations was 11.2 ± 4.1% (age group A) and 6.7 ± 3.3% (age group B), mean displacement 15.1 ± 8.3% (A) and 11.0 ± 6.2% (B). Systolic and diastolic aortic diameter and CoM position significantly differed at all locations (p<0.001). Distension and displacement could be predicted based on the regression model (p<0.001). Age group A and women exhibited significantly greater distension and displacement compared to age group B (p<0.001) and men (p<0.01), respectively. Distension increased, displacement decreased from proximal to distal.

Conclusion: Distension and translational displacement are significant at all levels of the thoracic aorta and can be predicted based on clinical characteristics.