Chronic thromboembolic pulmonary hypertension (CTEPH)

Clinical presentation:

Patient often complaining of dyspnea on exertion, chest pain, cough and syncope.

High risk patients: Cancer patient; chronic cardiac or pulmonary disease and clotting disorders.

Imaging manifestations:

Chest radiography would be normal early in the course of the development of CTEPH; later on there will be enlargement of the pulmonary arteries. Subpleural opacities representing recent or remote pulmonary infarction may be encountered. 

CTPA:

• The study of choice.
• Enlarged pulmonary artery.
• Eccentric filling defects representing organizing thrombi. 
• Linear intraluminal filling defects representing intravascular webs.
• Abrupt narrowing of the pulmonary arteries with reduction in the arterial diameter.
• Markedly hypertrophied bronchial arteries. 
• Right ventricular enlargement and hypertrophy. 

 HRCT:

• Mosaic perfusion.
• Small foci of subpleural scarring related to prior pulmonary infarction. 

Enlarged bronchial arteries may occur in the response to chronic right ventricular outflow tract or pulmonary arteries obstruction. In normal status it account for 1% of cardiac output; however; in case of CTEPH those demonstrate significant enlargement and a count as much as 30% of the cardiac output. Enlarged bronchial arteries are more commonly seen in patients with CTEPH than in patients with nonembolic causes of pulmonary hypertension, and the presence of these vessels tends to favor chronic PE over acute PE.  

Right ventricular enlargement and hypertrophy are seen on CTPA with leftward bowing of the interventricular septum. When tricuspid annulus dilates, tricuspid regurgitation develop and associated with reflux of contrast into the inferior vena cava. However; these findings can be seen as a result of increased right heart pressure in the absence of significant tricuspid valvular dysfunction.