Preliminary Diagnosis: Aortic Stenosis
I. What imaging technique is first-line for this diagnosis?
Transthoracic echocardiography (TTE)
II. Describe the advantages and disadvantages of this technique for diagnosis of aortic stenosis.
Advantages
- Echocardiographic imaging can define the valve anatomy, the underlying cause of aortic stenosis, and the severity of valve calcification.
- Doppler echocardiography measures the transaortic jet velocity, the pressure gradient, and the aortic valve area, which predicts disease severity and clinical outcome.
- It can also demonstrate aortic regurgitation, which may also be present with aortic stenosis.
- It is important in evaluating left ventricular hypertrophy and systolic function.
Disadvantages
- Poor chest windows secondary to body habitus or chest wall abnormalities lead to poor image acquisition and evaluation.
- Incorrect calculations can result from annulus calcification and eccentric jet morphology.
III. What are the contraindications for the first-line imaging technique?
None
IV. What alternative imaging techniques are available?
- Transesophageal echocardiography (TEE)
- MRI
- CT
- Angiography
- Plain film radiography
V. Describe the advantages and disadvantages of the alternative techniques for diagnosis of aortic stenosis.
TEE
Advantages
- Allows for very accurate measurement of the aortic valve orifice
- Improved visability of the aortic cusps compared with TTE
Disadvantages
- It is an invasive procedure that may be poorly tolerated by some patients.
- Conscious sedation is required.
MRI
Advantages
- Can assess disease severity by obtaining valve dimensions and calculating pressure gradients
- Demonstrates a systolic flow jet into the proximal aorta
- Can also evalute left ventricle volume and function
Disadvantages
- Long examination times may be difficult for claustrophobic patients.
CT
Advantages
- Noncontrast CT can assess aortic valve calcification.
- Cardiac-gated CT can demonstrate leaflet thickening and left venticle hypertrophy.
- Poststenotic dilation of the aorta may be demonstrated.
- CT can also reveal concomitant coronary artery disease and aortic regurgitation.
Disadvantages
- Exposure to ionizing radiation
- Necessary for IV contrast in patients who may have marginal renal function
Angiography
Advantages
- Angiography can accurately measure pressure gradients across the aortic valve, calculate the valve area, and assess the severity of disease.
- The coronary arteries may be evaluated before surgical intervention.
Disadvantages
- It is an invasive procedure with risks of complications including access site injury, infection, and bleeding.
Plain film radiography
Advantages
- Plain radiographs may demonstrate rounding of the left ventricular border and apex, left atrial enlargement, and dilation of the ascending aorta
- Calcification of the valve may be demonstrated.
- Poststenotic dilation of the aorta may be apparent.
Disadvantages
- It is a nonspecific screening exam.
VI. What are the contraindications for the alternative imaging techniques?
TEE
- Poor tolerance of sedation may be a relative contraindication.
MRI
- Noncompatible devices, such as pacemakers, some metallic implants, and aneurysm clips
- Renal failure due to the risk of nephrogenic systemic fibrosis if contrast is given
- Pregnancy during the first trimester may be a relative contraindication.
CT
- Renal failure due to the risk of contrast-induced nephropathy
- Pregnancy
- Contrast allergy may be a relative contraindication.
Angiography
- Renal failure due to the risk of contrast induced nephropathy
- Pregnancy
- Allergy to contrast material may be a relative contraindication.
Plain film radiographs
- No significant contraindications exist.
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