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.
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Epidemiology
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.
Associations
Pulmonary artery intramural hematoma has been strongly associated with the following conditions 1,2:
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acute aortic dissection: usually Stanford type A 1-3, but it has been also described in Stanford type B 4
Diagnosis
The diagnosis of intramural hematoma of the pulmonary arteries is typically established by typical radiological features on CT 1,2.
Clinical presentation
Symptoms are those of an acute aortic syndrome and include sudden onset of chest pain, dyspnea and hypertension 2.
Complications
Pulmonary artery intramural hematoma can lead to the following 1,2:
alveolar hemorrhage
pulmonary artery obstruction
Pathology
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.
Etiology
Pulmonary artery intramural hematoma can occur due to the extravasation of blood into the common aortopulmonary adventitia 1-3.
Radiographic features
Ultrasound
Echocardiography
On echocardiography pulmonary artery intramural hematoma might present as dilation of the pulmonary arteries with or without dilation of the right cardiac chambers 2.
CT
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.
Radiology report
The radiological report should include a description of the following:
extent and affected pulmonary arteries
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associated findings such as:
aortic intramural hematoma
acute aortic dissection
alveolar hemorrhage
hemopericardium
Treatment and prognosis
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.
Differential diagnosis
The differential diagnosis of pulmonary artery intramural hematoma includes 2:
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