Pulmonary artery intramural hematoma

Last revised by Yuranga Weerakkody on 18 Jul 2022

Pulmonary artery intramural hematoma (PA-IMH) refers to a hemorrhage within the wall of the pulmonary arteries. It can occur alone in the setting of a thoracic aortic injury or as a complication of an acute aortic dissection for example in a setting where the posterior wall of the aortic root is affected 1-4.

So far intramural hematoma of the pulmonary arteries has been considered rare and is not often described. However, it seems to occur in 9-16% of patients with Stanford type A acute aortic dissection 1-4.

Pulmonary artery intramural hematoma has been strongly associated with the following conditions 1,2:

The diagnosis of intramural hematoma of the pulmonary arteries is typically established by typical radiological features on CT 1,2.

Symptoms are those of an acute aortic syndrome and include sudden onset of chest pain, dyspnea and hypertension 2.

Pulmonary artery intramural hematoma can lead to the following 1,2:

  • alveolar hemorrhage
  • pulmonary artery obstruction

Pulmonary artery intramural hematoma is characterized by hemorrhage within the wall of the main pulmonary artery and/or left and right pulmonary arteries. The pulmonary arteries and the aorta share a common adventitia which constitutes a possible pathway for extravasation of blood in the setting of acute aortic dissection of the ascending aorta where the posterior wall is affected or a traumatic thoracic aortic injury 1,2. 

Pulmonary artery intramural hematoma can occur due to the extravasation of blood into the common aortopulmonary adventitia 1-3.

On echocardiography pulmonary artery intramural hematoma might present as dilation of the pulmonary arteries with or without dilation of the right cardiac chambers 2.

On CT pulmonary artery intramural hematoma might appear as a crescentic or circumferential high attenuation spreading along the course of the pulmonary arteries and with an obtuse angle towards the pulmonary arterial walls 1,2.

It might be associated with centrally located perivascular ground-glass opacities on the pulmonary window indicating alveolar hemorrhage 1,2.

The radiological report should include a description of the following:

  • extent and affected pulmonary arteries
  • associated findings such as:
    • aortic intramural hematoma
    • acute aortic dissection
    • alveolar hemorrhage
    • hemopericardium
    • aortic transection

So far the clinical significance of the prognosis and long-term sequelae of pulmonary artery intramural hematoma has not yet been established 2.

Since pulmonary artery intramural hematoma is strongly associated with Stanford type A aortic dissection treatment of the patient in this setting will be likely surgical 6-8.

The differential diagnosis of pulmonary artery intramural hematoma includes 2:

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