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Determinants of thoracic aortic size in normotensive and hypertensive individuals
Michael H C Pham1,2, Jørgen T Kühl3, Andreas Fuchs1,2
1Department of Cardiology, The Heart Center.
Aims:
Thoracic aortic diameter is modulated by various factors including both physiological and pathological mechanisms. The aim of this study was to explore the determinants of thoracic aortic size focusing on arterial blood pressure and physical activity in normotensive and hypertensive individuals.
Methods:
Ascending and descending aortic diameters were measured in participants of the Copenhagen General Population Study using thoracic CT angiography. To assess the relation between arterial blood pressure and thoracic aortic diameters, individuals with diabetes, hypercholesterolemia, smoking, and prescribed antihypertensive medication were excluded. Intensity of physical activity was recorded based on self-reported questionnaire data.
Results:
A total of 1214 normotensive and 284 hypertensive individuals were examined. In all individuals, male sex, older age, and body surface area were associated with higher diameters of the ascending and descending aorta ( P < 0.01). In normotensive individuals, hard physical activity > 4 h/week was independently associated with higher thoracic aortic diameters (ascending β:1.09[0.52;1.66] and descending β : 0.47[0.14;0.80], both P < 0.01), whereas higher systolic blood pressure was not associated with thoracic aortic diameters (ascending P = 0.12 and descending p = 0.33). In hypertensive individuals, higher systolic blood pressure (per 10 mmHg) was independently associated with higher thoracic aortic diameters (ascending β : 0.55[0.17;0.94] and descending β : 0.23[0.10;0.37] mm/10 mmHg, both P < 0.01), whereas hard physical activity was not associated with higher aortic diameters (ascending P = 0.11 and descending P = 0.51).
Conclusion:
In normotensive individuals hard physical activity, and in hypertensive individuals increasing systolic blood pressure are factors each independently associated with larger thoracic aortic size. These findings suggest a context sensitive mode of aortic vascular response to size modulating adaptation.
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Monitoring Both Arms:
Monitoring BP in both arms during the initial assessment is advisable, as the systolic value may differ by five to ten mm Hg between arms. For subsequent BP assessments, use the arm with the higher reading.