Imaging

Mitral Stenosis

Preliminary Diagnosis: Mitral stenosis

I. What imaging technique is first-line for this diagnosis?

  • Transthoracic echocardiography

II. Describe the advantages and disadvantages of this technique for diagnosis of mitral stenosis.

Advantages

  • Most accurate approach to diagnosis

  • Echocardiography reveals leaflet thickening, symmetric fusion of the commissures, and doming of the anterior mitral leaflet. Left atrial enlargement may also be demonstrated

  • Color Doppler can determine the transvalvular pressure gradient as well as the area of the mitral valve orifice.

Disadvantages

  • Additional transesophageal echocardiography may be required before surgery to clarify the etiology of stenosis and evaluate for left atrial appendage thrombus.

III. What are the contraindications for the first-line imaging technique?

  • No significant contraindications

IV. What alternative imaging techniques are available?

  • Transesophageal echocardiogram (TEE)

  • CTA

  • MRI

  • Plain-film radiographs

  • Angiography

V. Describe the advantages and disadvantages of the alternative techniques for diagnosis of mitral stenosis.

TEE

Advantages

  • Provides detailed images of the mitral valve

  • Can also exclude left atrial thrombus

Disadvantages

  • May be poorly tolerated by some patients

  • Invasive and requires sedation

CTA

Advantages

  • Cardiac-gated CTA can demonstrate doming of the anterior leaflets and narrowing of the mitral valve orifice

  • Left atrial enlargement and thrombus can often be identified

  • The leaflets may appear thickened or fused

Disadvantages

  • May overestimate the mitral valve area

  • Physiologic valve area determined by TEE correlates better clinically than anatomic valve area

  • Does not provide hemodynamic data, such as pressure gradients

  • Exposes the patient to ionizing radiation

  • Exposes the patient to iodinated contrast

MRI with contrast

Advantages

  • Can determine mitral valve area, flow velocities, and pressure gradients

  • Spin-echo MRI can demonstrate thickening and bulging of the leaflets and dilation of the left atrium.

Disadvantages

  • Limited value in cases with atrial fibrillation

  • Expensive

  • Requires significant patient cooperation to minimize motion artifact

  • Long examination time may be difficult for claustrophobic patients

Plain film radiographs

Advantages

  • Left atrial enlargement can be observed on lateral images

  • In severe cases, enlargement of pulmonary arteries, right ventricle and right atrium can be demonstrated.

  • The mitral valve may appear calcified.

  • Interstitial pulmonary edema suggests pulmonary venous hypertension and severe mitral stenosis.

Disadvantages

  • Findings are nonspecific and best utilized as a screening exam or to follow symptoms

Angiography

Advantages

  • Provides accurate measurements of left atrial and left ventricular pressures as well as pulmonary hypertension

  • Can perform simultaneous right and left heart pressure measurements

  • Mitral-valve area may be calculated

Disadvantages

  • It is an invasive procedure that is only indicated when echocardiography is nondiagnostic or results are discrepant with clinical findings.

VI. What are the contraindications for the alternative imaging techniques?

TEE

  • Poor tolerance of sedation may be a relative contraindication

CTA

  • Renal failure due to risk of contrast-induced nephropathy

  • Pregnancy

  • Contrast allergy may be a relative contraindication

MRI

  • Renal failure due to risk of nephrogenic systemic fibrosis if contrast is given

  • Pacemakers, aneurysm clips, and other metallic implants that are not MRI compliant

  • Pregnancy may be a relative contraindication in the first trimester

Plain film radiographs

  • No significant contraindications exist. Some institutions may require consent for pregnant patients.

Angiography

  • Renal failure due to risk of contrast-induced nephropathy

  • Pregnancy

  • Contrast allergy may be a relative contraindication

  • Hypocoagulable states (platelets <50k or INR>2.0).

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