Imaging

Aortic Stenosis

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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