Thickening of the pulmonary artery wall in acute intramural hematoma of the ascending aorta

Acute aortic dissection, acute intramural hematoma and aortic penetrating ulcer are entities with high mortality known as acute aortic syndromes. The usual fatal course of these conditions is closely related to their lethal complications [1]. The most frequent complications are rupture of the aorta with hemorrhage into the pericardial cavity, pleural space or mediastinum, or the occurrence of acute aortic valve regurgitation. The involvement of the pulmonary artery with wall thickening or even pulmonary flow obstruction in these circumstances is far less common. There are few reports in the literature of pulmonary artery involvement in the course of acute aortic dissection, but none of them in the scenario of acute intramural hematoma.

An 87-year-old woman with history of systemic hypertension and dyslipidemia was admitted to our hospital after having had severe chest pain of sudden onset radiating to the back and followed by syncope. She presented with marked hypotension (60/40), sinus tachycardia (130 beats per minute), and livid legs. She needed oral tracheal intubation, mechanical respiratory assistance, volume expansion and inotropic support. An urgent transesophageal echocardiogram revealed aortic intramural hematoma compromising the anterior wall of the ascending aorta (Fig. 1) with no evidence of aortic dissection, and severe pericardial effusion with cardiac tamponade and periaortic hematoma that involved the pulmonary artery generating circumferential wall thickening of its trunk (Fig 2) and right branch (Fig. 3) with no evidence of flow obstruction (Fig. 4) [see Additional file 1]. Urgent surgery was performed (drainage of pericardial hematoma and replacement of ascending aorta) but the patient died in the operating room.

The post mortem examination, in the operating room, confirmed that there was an extensive hematoma around the aorta and beneath the adventitial layer of the pulmonary artery with no evidence of flow obstruction.

This rare complication of the acute aortic syndromes has been carefully described by Buja et al. in a case of aortic dissection [2]. Since the ascending aorta and pulmonary trunk share a common adventitia, the extravasation of blood into the adventitia of the ascending aorta may well extend into the adventitia of the pulmonary artery producing thickening of the artery wall and even causing, at times, compression of the pulmonary trunk or its main branches. Since extravasated blood in the adventitia is driven by aortic pressure, it can compress the lumen of pulmonary artery, which has relatively low pressure. The resultant hematoma in the adventitia around the pulmonary arteries plays an essential role in obstruction of these vessels, with no compromise of the medial layer. Given that it is located just behind the ascending aorta, obstruction often involves the right pulmonary artery [3].

There are few reports of this rare complication of acute aortic syndromes in the literature. Many of these reports are in patients who were initially thought to have pulmonary embolism. Indeed the ventilation-perfusion lung scan demonstrates mismatched absence of perfusion to the entire right lung in these cases [4, 5]. Furthermore, a patient with this condition was treated with intravenous heparin and urokinase after being wrongly diagnosed with pulmonary embolism [6]. This rare complication should be kept in mind since the misdiagnosis as thromboembolism can lead to delayed and/or incorrect treatment in a particularly critical patient.

The reason we thought of presenting this case is threefold – there are few reports of this uncommon complication of acute aortic syndromes in the literature; this is the first time that it is described in the scenario of acute intramural aortic hematoma; and it is the first time that transesophageal echocardiogram is used as the diagnostic tool [7‐9].

The transesophageal echocardiogram seems to be an accurate diagnostic tool not only to diagnose the aortic pathology but also to rule out this uncommon complication.