From the Guidelines
The normal aortic root diameter typically ranges from 2.0 to 3.7 cm in adults, with variations based on age, gender, and body size, and referral to a cardiologist or cardiothoracic surgeon is generally recommended when the aortic root diameter exceeds 5.5 cm or shows rapid enlargement (greater than 0.5 cm per year) 1.
Key Considerations
- The aortic root diameter can vary based on age, gender, and body size, with average diameters ranging from 34.1 ± 3.9 mm for the ascending thoracic aorta in men and 31.9 ± 3.5 mm for women 1.
- Patients with genetic conditions predisposing to aortic dilation, such as Marfan syndrome, Loeys-Dietz syndrome, or bicuspid aortic valve, may require referral at smaller diameters (4.0-4.5 cm) due to their higher risk of complications 1.
- Monitoring of aortic root size is typically done via echocardiography, CT, or MRI imaging, with regular follow-up imaging at 6-12 month intervals recommended for patients with borderline enlargement to monitor for progression 1.
Referral Thresholds
- For asymptomatic patients with aneurysms of the aortic root or ascending aorta, surgery is indicated when the maximum diameter exceeds 5.5 cm, and is reasonable when the diameter exceeds 5.0 cm and performed by experienced surgeons in a Multidisciplinary Aortic Team 1.
- For patients with Marfan syndrome, an aortic root diameter of 4.5 cm or greater and features associated with an increased risk of aortic dissection, surgery to replace the aortic root and ascending aorta is reasonable 1.
- For patients with a bicuspid aortic valve, a diameter of the aortic root or ascending aorta of 5.0 to 5.4 cm and an additional risk factor for aortic dissection, surgery to replace the aortic root and/or ascending aorta is reasonable when performed by experienced surgeons in a Multidisciplinary Aortic Team 1.
From the Research
Normal Size of Aortic Root
- The normal size of the aortic root varies according to age, sex, and race 2.
- Studies have shown that all aortic root dimensions are larger in men compared to women, and after indexing to body surface area (BSA), all measured dimensions are significantly larger in women 2.
- The upper limits of normal for all aortic dimensions are lower across all age groups compared to current guidelines 2.
- Aortic dimensions are larger in older age groups in both sexes, a trend that persists regardless of BSA or height adjustment 2.
- Asians have the smallest non-indexed aortic dimensions at all levels 2.
Referral Criteria
- An aortic root diameter greater than the upper limit of normal for the individual's age, sex, and race may indicate the need for referral 3, 4.
- High aortic root dimension is associated with an increased risk of incident congestive heart failure, stroke, cardiovascular mortality, and all-cause mortality 3.
- The full range of aortic root diameters by transthoracic echocardiography has been established, providing a basis for detecting aorta dilatation and planning therapeutic interventions 5.
- Aortic root dimensions can be significantly underestimated with measurements performed in only one plane, emphasizing the importance of using multiple imaging modalities and planes to accurately assess aortic root size 6.