What is calcification in the aorta?

What is Calcification in the Aorta

Aortic calcification is the deposition of calcium in the aortic wall, representing a central component of atherogenesis that signals long-standing inflammation and directly correlates with the extent of atherosclerosis. 1

Pathophysiology and Types

Aortic calcification occurs through two distinct mechanisms:

• Intimal calcification develops as part of atherosclerosis, beginning with a patchy distribution in the innermost layer of the aortic wall 2
• Medial calcification (Mönckeberg's arteriosclerosis) occurs in the middle layer of the vessel wall, often appearing more concentric and associated with metabolic disorders, aortitis, and radiation-associated cardiovascular disease 2

The atherosclerotic process involves massive intimal thickening with fibrosis and calcification, typically at the edges of plaques 3. This compromises the nutrient supply to the media, resulting in smooth muscle cell necrosis and fibrotic changes in elastic structures, ultimately increasing vessel stiffness and vulnerability to shear stress 3.

Clinical Significance and Prognosis

The presence of aortic calcium predicts coronary heart disease and is associated with increased risk of death and cardiovascular disease. 1

Prognostic Implications:

• Calcification of the thoracic aorta correlates with coronary calcification, aortic valve calcification, and mitral annulus calcification 4, 5
• Age-adjusted hazard ratios for cardiovascular events in patients with aortic calcification are 2.70 (95% CI, 1.33 to 5.47) 5
• Severe calcification (thickness ≥5 mm) of the descending aorta increases the risk of ischemic cerebrovascular events by nearly 5-fold (OR 4.9,95% CI 1.8 to 13.5) 4
• Abdominal aortic calcification is associated with increased mortality, coronary heart disease, and stroke 6

Porcelain Aorta

The most severe form of aortic calcification is termed "porcelain aorta":

• Appears as an "eggshell" pattern with curvilinear calcifications on chest x-ray or CT 7
• Represents circumferential calcification that significantly increases the risk of stroke and distal embolism during cardiac procedures 1, 7
• Direct manipulation may result in unrepairable aortic injury and/or distal embolization 7
• Documented in 15.1% of inoperable patients in the PARTNER trial 7

Diagnostic Assessment

Imaging Characteristics:

• Chest x-ray or CT can detect calcification, with CT being superior for quantifying extent and location 1, 7
• Calcification severity can be graded semi-quantitatively as mild (few areas of dense echogenicity), moderate (multiple larger areas), or severe (extensive thickening with prominent acoustic shadow) 3
• Echocardiography can identify valve calcification but is less sensitive for aortic wall calcification 3

Risk Factors:

• Increasing age is the strongest predictor 4, 5
• Hypertension (present in 85% of patients with ruptured aneurysms) 3
• Smoking 4, 6
• Positive correlation with coronary calcification and valvular calcification 4, 5

Management Implications

Medical Management:

Implement aggressive cardiovascular risk factor modification including blood pressure control, lipid management, diabetes control, and smoking cessation. 1

Surgical Considerations:

When cardiac surgery is required in patients with significant aortic calcification:

• Document the extent and location of calcification for surgical planning 1
• Special surgical techniques are necessary, including internal aortic balloon occlusion instead of cross-clamping 1, 7
• Use "no-touch" technique to completely avoid the ascending aorta 1, 7
• Consider alternative cannulation sites (axillary/subclavian, femoral, or innominate arteries) 7
• Alternative locations for coronary bypass graft anastomoses may be required 1
• Replacement of the ascending aorta when necessary 1

Procedural Planning:

• Porcelain aorta is classified as an anatomic factor making patients high risk for surgical aortic valve replacement and represents a specific indication favoring transcatheter aortic valve replacement (TAVR) over conventional surgery 7
• Assess extent of aortic calcification as part of pre-procedural TAVR planning, as it affects device selection and delivery approach 1
• Ascending aortic calcification is associated with increased risk of heart failure following TAVR 1

Special Populations

Dialysis Patients:

• Increased prevalence of aortic and valvular calcification compared to age-matched controls 3
• High doses of calcium-based phosphate binders (mean 6,456 mg daily) are associated with progression of calcification 3
• Hyperphosphatemia and elevated calcium-phosphorus product (>55) drive vascular calcification through induction of bone-forming proteins in vascular smooth muscle 3
• Non-calcium-based phosphate binders (sevelamer) prevent progression of calcification compared to calcium-based binders 3