Introduction
Massive haemoptysis is defined as the expectoration of greater than 500ml of blood per day and has a mortality rate of more than 50%. Most patients have bronchial artery (BA) and/or nonbronchial systemic artery (NBSA)-related haemoptysis, with only 5-10% of patients having pulmonary artery (PA)-related haemoptysis [
1].
Haemoptysis is also caused by pulmonary artery pseudoaneurysms (PAPs), which have diverse aetiologies, including trauma, iatrogenesis (percutaneous lung biopsy or tumour ablation), infection (tuberculosis, aspergillosis), and tumours [
2]. The 1-year mortality rate of patients with a PAP is approximately 50–100%, and the main cause of PAP-related deaths is asphyxia caused by rapid and massive intrapulmonary haemorrhage [
3,
4]. Therefore, early diagnosis and treatment are crucial for the prognosis and survival of PAP patients.
In 1960, pneumonectomy was reported to reduce mortality by up to 15% for PAP patients. Due to the high risk of surgery and the fact that some patients cannot tolerate surgery, BAE or NBSAE is suggested as first-line measures in most studies. Research also shows that 38% of patients who have successfully experienced BAE or NBSAE will have haemoptysis again [
5]. There are only few literature reports on the management of PAPs through the PA pathway during simultaneous BAE and NBSAE if there are BA-PA or NBSA-PA fistulas. The main purposes of this study were to retrospectively analyse the outcomes of 23 PAP patients with massive haemoptysis, explore the safety and efficacy of PAPE and BAE and/or NBSAE for such patients, and provide feasible treatment methods for massive haemoptysis caused by pulmonary pseudoaneurysm.
Discussion
PAP induces a large amount of dark haemoptysis with no specific clinical manifestations in the intermittent stage [
10,
11]. In this study, all 23 patients were admitted to the hospital due to massive haemoptysis, and a PAP was found during CTA before intravascular treatment. Most patients had an abnormally dilated tortuous BA and/or NBSA, but it could not be determined whether there was a definite BA and/or NBSA-PA fistula.
The upper lobe of the lungs is involved in recurrent tuberculosis [
2,
12,
13,
14]. In this study, 2, 8, and 7 cases were located in the upper lobe of both lungs, upper lobe of the right lung, and upper lobe of the left lung, respectively (73.91% of the patients), which were consistent with the reported literature [
11]. A PAP was detected in all the patients, of which two cases were reported in the main pulmonary lobar arteries (8.70%), and 21 cases were reported in the pulmonary lobar artery branch (91.30%). However, in the largest retrospective study conducted to date, a PAP was detected in 83% of patients, of which 63% of cases occurred in the pulmonary artery subsegment [
11]. The discrepancy in this study could be because of the small sample size, or because most patients had pulmonary tuberculosis.
The source of bleeding can be first detected by CTA combined with PA and BA/NBSA angiography, providing information on the location, size, quantity, shape, and origin of PAP. In addition, CTA and angiography can detect dilation and tortuosity of the BA and NBSA [
6,
8]. In this study, a PAP was detected by thoracic CTA in all the patients. An abnormally dilated tortuous BA or NBSA was also detected in most patients, but it could not be determined whether there were definite BA and/or NBSA-PA fistulas.
However, there is no consensus regarding the treatment guidelines for PAP. Conservative treatment can be conducted once the cause of PAP is identified to prevent rupture and bleeding. However, medication alone may not be effective in preventing an enlarged or ruptured PAP in patients with massive haemoptysis. Although various nonendovascular methods, such as image-guided percutaneous direct puncture embolization, PAP resection, and lobotomy, are applied in the treatment of patients who cannot receive endovascular treatment, they are associated with high mortality [
15‐
18].
Endovascular treatment is minimally invasive, safe, and effective and is associated with low mortality. Endovascular therapy using different embolization materials has been explored. However, liquid embolization is poorly controlled and may result in ectopic embolism, pulmonary infarction, or catheter adhesion risk. Furthermore, vascular embolization can only embolize the inflow tract but cannot completely embolize the cavity and outflow tract, and thus, the blood may cause a countercurrent flow into the cavity. As a result [
6,
8,
19], coil embolization, as a safe and effective method, is widely used for systemic aneurysms or pseudoaneurysms [
20‐
22]. However, breathing or coughing is associated with a high risk of PAP rupture and position change during coil embolization. Therefore, coil embolization procedures should be carefully performed. The interlocking microcoil is very flexible and can be implanted via a microcatheter to ensure that the coil is very smooth in propulsion and can pass through very tortuous vessels. In addition, the forwards thrust force is small once the catheter has been inserted into the cavity, thus reducing the possibility of cavity rupture. Furthermore, the catheter tail has a mechanical torsion lock structure; thus, it can be recovered and released after adjustment if the release position is not ideal as long as the mechanical twist locking device of the tail is in the catheter [
23]. In this study, interlock microcoils were used as PAP embolization material in all the patients.
PAP in the main pulmonary lobar arteries should be embolized with microcoils assisted by a bare stent. This is mainly because it is difficult for the coils to build a stable coil pack for wide-necked aneurysms. Furthermore, lung tissue contraction and expansion movements during breathing may cause coil migration for narrow-necked aneurysms. Although the covered stent can resolve the localized stenosis and isolate the aneurysm, the patency time of the covered stent is shorter than that of the bare stent, and the push delivery system of the covered stent is thicker, resulting in poor flexibility of the stent. This significantly increases the difficulty of release, and the tumour cavity cannot be filled. Microcoils combined with bare stents can more tightly embolize and make PA blood flow faster. The stent can resolve the PA stenosis caused by the inflammatory tissue around the aneurysm. Furthermore, the bare stent push device is thinner, more compliant than the covered stent, and easier to operate.
Embolization of a PAP in the pulmonary lobar artery branch vessels is relatively simple. In this study, an appropriately selected microcatheter was advanced as far as possible into the PA, and embolization was performed from the distal part of the pseudoaneurysm neck, resulting in the complete embolization of the entire aneurysm. This was conducted to prevent blood from returning to the aneurysm cavity and causing rupture and bleeding.
However, endovascular therapy for PAPs is relatively complex due to the presence of a BA and/or NBSA-PA fistula. As a result, PA angiography may not detect PAPs due to an A-P shunt but may be visible under BA and/or NBSA angiography [
24]. As a result, simple embolization of the PAP and parent pulmonary artery may lead to recurrence. In this study, all patients underwent CTA of the BA and NBSA. A BA and/or NBSA-PA fistula was detected in 19 patients (82.61%) and was treated with embolization. In PAPE, the catheter was placed in the target BA and/or NBSA and then BAE and/or NBSAE was performed. PAPs be easily detected via pulmonary angiography before BAE and/or NBSAE.
A BA-PA and/or NBSA-PA fistula may be caused by pulmonary and pleural infection, pneumothorax, malignant tumour, or chest trauma leading to pulmonary hypertension [
25‐
27]. Our results indicate that BA and/or NBSA-PA fistulas significantly increase PA pressure because the pressures and velocities of the BA and NBSA supplied by the systemic circulation are higher than those of the pulmonary artery [
28,
29]. However, the fistula disappeared after embolization, and the PA pressure decreased. Furthermore, PAP coil embolization alone or pulmonary artery branch embolization did not significantly increase the PA pressure, suggesting that embolization is safe.
Although endovascular PAP therapy is less risky than surgery, it has similar risks to other systemic endovascular embolization procedures, including contrast-induced nephropathy, ectopic embolism, vascular dissections, thrombosis, and tissue infarction. In this study, 11 patients had postoperative chest and back pain, discomfort, and other minor complications, possibly caused by ectopic embolization during protective embolization or by a granulated embolization agent during NBSAE.
However, this study has some limitations. First, the sample size was small, thus limiting the generalizability of the conclusions. Second, a prospective, randomized, multicentre study is needed to clarify the effectiveness of PAPE for the treatment of massive haemoptysis.
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