This study demonstrates the safety and efficacy of treating pulmonary artery pseudoaneurysms of various etiologies by embolizing the pseudoaneurysm sac with permanent embolic agents. All but two patients and cases were treated by embolizing the inflow pulmonary artery and pseudoaneurysm sac, and in most cases embolizing the pulmonary artery outflow as well. Previous studies evaluating mycotic aneurysms were treated with both pulmonary artery embolization and systemic-bronchial artery embolization. The rationale behind this treatment is the known phenomena of systemic-pulmonary fistulas in the setting of chronic lung inflammation7. However, in this study the bronchial arteries were neither interrogated nor embolized, including in the seven patients with mycotic aneurysm, chronic lung disease and lung neoplasm for which systemic-pulmonary artery fistulas can arise. The rationale for treatment of the pseudoaneurysm sac, ideally with both inflow and outflow embolization is that any backflow from systemic arteries should be sufficiently prevented from filling the aneurysmal sac. Although the bronchial arteries do not routinely need to be interrogated if the aneurysm is identified on pulmonary angiography, careful attention to possible shunting must be made. In this study no shunting was identified and PVA was safely used in three cases.
Pulmonary angiography generally requires pre-procedural imaging or a high suspicion for pulmonary arterial injury. In this study, eleven patients had pre-procedural imaging (11/13), five of which showed clear pseudoaneurysm on CTA and four demonstrating nonspecific contrast irregularity likely arising from the pulmonary arteries on routine CT. In two cases a large lung tumor with close involvement of the pulmonary artery was suggestive of the need to interrogate the pulmonary arteries rather than systemic arteries. In one case, a patient developed a pseudoaneurysm with active extravasation causing hypotension during a cardiac right heart catheterization. This was emergently treated by the interventional radiology team in the cardiac catheterization lab, obviating the need for pre-procedural imaging. Similarly, a second patient who was immediately post cardiac catheterization developed massive hemoptysis. This patient was immediately brought to the interventional suite with coil embolization of the pulmonary artery aneurysm inflow, sac, and outflow. However, shortly before closure the patient developed ventricular tachycardia and went into cardiac arrest for which resuscitation was unsuccessful.
Embolization of the pseudoaneurysm sac proved to be effective. There was only one case of minor recurrent hemoptysis secondary to reperfusion which was treated with PVA particles injected into the new feeding pulmonary artery. There were no major complications and only two minor self-resolving episodes of pleuritis. There were two extenuating cases where the pseudoaneurysm sac was not embolized. One case already mentioned, an intraprocedural aneurysm with active extravasation occurred resulting in hypotension, necessitating rapid cessation of bleeding and a proximal embolization of the feeding artery was performed. The second case involved a large irregular PSA arising from the left main pulmonary artery, secondary to a large lung tumor, for which embolization of the sac was not technically feasible. In this case, PVA was injected distally to prevent back filling of the PSA, a large Amplatzer plug was placed across the PSA.
Pulmonary artery pseudoaneurysms are both emergent and ominous findings. Of the ten patients who were treated at least one year prior to the date of this study, half of the PAPs (5/10) were noted to be deceased at the time of this study. The average survival period in these five patients was 7-months with a range of 0–14 months. More specifically, of the ten patients treated at least one year prior to the time of the study who presented with massive hemorrhage or hemoptysis, 5/6 were found to be deceased at the time of the study. All deaths were due to underlying disease, i.e., cardiac disease and lung neoplasms.
There are limitations of this study, the most significant being the small patient population in this study. Another limitation is the differentiation between true aneurysms and pseudoaneurysm. True peripheral pulmonary artery aneurysms and pseudoaneurysms typically cannot be differentiated based on imaging and are therefore assumed based on history. Little literature exists describing true aneurysms and the two entities are typically managed as one6. Therefore, some of these lesions, especially the two patients with idiopathic lesions, may represent true aneurysms rather than pseudoaneurysms, although there is no medical history (i.e., congenital heart disease or connective tissue disease) to support the diagnosis of true aneurysm. Given the peripheral location and morphology being inseparable from pseudoaneurysms, as well as the theoretical risk of rupture, these incidental lesions were treated in the same manner as known pseudoaneurysms.