Imaging

Congestive Heart Failure

Preliminary Diagnosis: Congestive Heart Failure

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

Chest radiography.

II. Describe the advantages and disadvantages of this technique for diagnosing congestive heart failure.

Advantages

  • Vascular distribution can indicate increased left-ventricular filling pressure.

  • Kerley lines, peribronchial cuffing, and ill-defined vessel margins sugget interstitial edema.

  • A "batwing" pattern of perihilar opacity is demonstrated in alveolar edema.

  • Increased vascular pedicle width corresponds to increased systemic blood volume.

  • Cardiomegaly can be diagnosed when heart size is >1/2 the thoracic diameter.

  • Simple and cost-effective.

Disadvantages

May be difficult in critically ill patients unable to hold their breath and position easily.

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

None. However, proper procedures should be taken in pregnant patients.

IV. What alternative imaging techniques are available?

  • Transthoracic echocardiography.

  • CT with intravenous contrast.

  • MRI.

  • PET/SPECT.

V. Describe the advantages and disadvantages of the alternative techniques for diagnosing congestive heart failure.

Transthoracic echocardiography

Advantages

  • Can determine systolic ejection fraction.

  • Can evaluate valvular and left ventricular morphology.

  • Quick and easy to perform.

Disadvantages

  • Normal echocardiography does not exclude pulmonary edema.

  • Poor windows due to body habitus can lead to suboptimal images.

CT with intravenous contrast

Advantages

  • Can show interlobular septal thickening, bronchovascular bundle thickening, and ground-glass opacities, which indicate pulmonary edema.

  • ECG gated coronary CT data can calculate ejection fraction accurately.

  • May reveal the underlying cause of heart failure, such as valvular disease or CAD.

Disadvantages

  • Artifact from pacemakers can obscure anatomy.

  • Exposure to ionizing radiation.

  • Exposure to iodinated contrast material.

MRI

Advantages

  • Can determine ejection fraction with good reproducibility and correlation with echocardiography.

  • Can help distinguish underlying CAD from dilated cardiomyopathy as the underlying etiology of heart failure.

Disadvantages

  • Long examination times may be difficult for claustrophobic patients.

  • Relatively expensive examination.

SPECT/PET

Advantages

  • Measures EF and chamber volumes.

  • Nuclear methods do not require an assumption of ventricular geometry when calculating EF.

  • Nuclear imaging is helpful for diagnosing CAD as the etiology of heart failure.

Disadvantages

Guidelines do not recommend routine evaluation of LV function with nuclear imaging in the absence of information obtained with another modality, such as echocardiography.

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

Transthoracic echocardiography

No significant contraindications exist.

CT with intravenous contrast

  • Risk of contrast-induced nephropathy in patients with renal failure.

  • Contraindicated during pregnancy.

  • Contrast allergy is a relative contraindication.

MRI

  • Certain metallic implants, such as pacemakers and aneurysm clips, may not be MRI compliant.

  • Risk of nephrogenic systemic fibrosis in patients with renal failure.

  • Pregnancy in the first trimester may be a relative contraindication.

SPECT/PET

  • Contraindicated during pregnancy.

  • Contraindicated while breast feeding.

Plain-film radiography

No significant contraindications exist.

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