Surgical Therapy for Pulmonary Artery Aneurysm

Abstract

Background

Pulmonary artery aneurysm is a rare disease, with only limited reports available in the literature and no current guidelines for management. In this study, we report the course of patients with pulmonary artery aneurysms that were repaired surgically. We also discuss the surgical indication for and management of pulmonary artery aneurysm.

Methods

This report describes a retrospective study in our institution (University of Utah School of Medicine, Salt Lake City, UT). We included patients who underwent pulmonary artery aneurysm repair from 2010 to 2024. We collected preoperative and surgical information on these patients retrospectively by reviewing their charts.

Results

A total of 11 patients underwent pulmonary artery aneurysm repair during this period. The aneurysm extended to branches in 7 patients. Pulmonary valve involvement was seen in 9 patients. Pulmonary hypertension was noted in 5 of 8 patients. Seven patients underwent graft replacement, 3 patients underwent aneurysmorrhaphy, and 1 patient underwent double-lung transplantation. Only 1 of the 11 patients died.

Conclusions

Given that there is no guideline for the management of pulmonary artery aneurysm, a surgical indication needs to be considered on a case-by-case basis. If the risks of surgery are thought to outweigh the benefits, conservative management is also an option even if the pulmonary artery diameter is greater than 55 mm. Surgical repair of pulmonary artery aneurysm, including graft replacement and aneurysmorrhaphy, can be performed safely. Replacement with a Dacron graft is the most common and feasible approach.

In Short.

• ▪We recommend surgical intervention for PAA once the PA diameter exceeds 55mm or has a greater than 5-mm increase in 6 months.
• ▪Replacement with a Dacron graft is the most common and feasible approach for PAA.

Because of the low incidence of pulmonary artery aneurysm (PAA), management of this disorder is still controversial, and there are no definitive guidelines related to medical or surgical approach or indications for intervention. Only a few reports are available on the surgical management of PAA. Most of these publications are case reports. Here we describe a case series that offers different perspectives regarding diagnosis and surgical therapy that we hope will provide a resource for future patients with this rare disease.

Patients and Methods

Study Population

This is a retrospective study in a single institution (University of Utah School of Medicine, Salt Lake City, UT). The Institutional Review Board approved this study, and specific informed consent was waived because of the determination of minimal risk to the patients. We used the department database to collect all the data. From 2010 to 2024, 229 patients received a diagnosis of PAA at our institution. PAA is defined as a diameter greater than 40 mm measured in the trunk of the pulmonary artery (PA). We used computed tomography with a pulmonary embolism protocol to diagnose PAA. Among these 229 patients, 11 underwent surgery for PAA.

Baseline Characteristics and Operative Data

Data on baseline preoperative characteristics were collected from the medical record. The patients’ age, sex, size of main PA, location of aneurysm (main PA, right PA, or left PA), pulmonary valve condition, PA pressure, and preoperative symptoms were evaluated. In addition, we collected data from the operative notes on the PA procedure type, concomitant surgery, cardiopulmonary bypass (CPB) time, and aortic cross-clamp time.

Results

Baseline Characteristics

Among the 11 patients who underwent surgery for PAA, measures of variations in baseline characteristics were presented as mean ± SD. The age of these patients was 49 ± 14.2 years. There were 7 male and 4 female patients in the group. The maximum diameter of the main PA was 53.1 ±17.5 mm. Seven patients had pulmonic valve regurgitation, 2 patients had normal pulmonic valve, 1 patient had pulmonic valve stenosis, and 1 patient had prosthetic pulmonic valve endocarditis (this patient had a history of pulmonic valve replacement). Eight of the 11 patients underwent preoperative right-sided heart catheterization, and PA hypertension (PH) was seen in 4 patients. Systolic PA pressure was 48.6 ± 20.7 mm Hg, and mean PA pressure was 30.3 ± 14.3 mm Hg. All except 1 patient had symptoms, including shortness of breath, dyspnea on exertion, fatigue, and chest pain, or bacteremia. Baseline characteristics are summarized in Table 1.

Table 1.

Baseline Characteristics of the Patients

No.	Age, y	Sex	PA, mm	Location	Pulmonic Valve	PA Pressure, mm Hg	Symptoms
1	53	Male	70	Main only	Severe PS	No data	SOB, dyspnea
2	72	Male	47	Main only	Severe PR	49/10 (24)	Fatigue, dyspnea
3	53	Male	59	Left	Normal	25/10 (17)	No symptoms
4	49	Female	54	Main, rt, lt	Severe PR	38/10 (19)	SOB
5	50	Female	68	Main, rt, lt	Mild PR	26/11 (17)	Chest pain, SOB
6	52	Female	74	Main, rt, lt	Mild-moderate PR	80/31 (48)	Dyspnea
7	62	Male	109	Main, rt, lt	Moderate-severe PR	74/37 (51)	Respiratory failure
8	30	Male	55	Main only	Severe PR	No data	Heart failure
9	50	Male	61	Main, rt	Severe PR	No data	Dyspnea
10	19	Male	44	Main, rt, lt	Endocarditis	39/13 (24)	Bacteremia
11	46	Male	42	Main only	Normal	58/32 (42)	SOB

lt, left; PA, pulmonary artery; PR, pulmonic valve regurgitation; PS, pulmonic valve stenosis; rt, right; SOB, shortness of breath.

PA pressure is shown as systolic/diastolic (mean).

Operative Data

PA replacement with a Dacron graft was performed in 5 patients, and a homograft was used in 2 patients. Aneurysmorrhaphy was performed in 3 patients, and 1 patient underwent double-lung transplantation. Five patients had a history of cardiothoracic procedures and required redo sternotomy. Moreover, concomitant procedures were performed in 8 patients. Mean CPB time was 204 ± 99.7 minutes, and mean aortic cross-clamp time was 121 ± 86.4 minutes. Seven patients required an aortic cross-clamp as a result of concomitant procedures and to have better exposure. No one required circulatory arrest. The mean follow-up time was 53.2 months, ranging from 4 to 172 months. One patient died, on postoperative day 27. The data are summarized in Table 2.

Table 2.

Patients’ Surgical Details

No.	Surgery	Concomitant Surgery	Surgical History	CPB, min	Cross-clamp, min	Follow-up, mo
1	PA replacement with 30-mm homograft	Patent foramen ovale closure	…	138	94	172
2	PVR, aneurysmorrhaphy	CABG × 1	…	85	0	118
3	PA replacement with 24-mm graft	No	…	117	75	32
4	PVR, aneurysmorrhaphy	Tricuspid valve repair	…	174	92	26
5	PA replacement with 26-mm graft, rt PA with 22-mm graft	Ligation of rt PA and coronary artery fistula	H/o patent ductus arteriosus closure	173	124	25
6	Main, rt, lt PA replacement with 30-mm graft	No	…	147	107	7
7	Main, rt, lt PA replacement with 38-mm graft, PVR with valved conduit	CABG × 2, ECMO	S/p PTE 5 years previously	448	293	Died on POD 27
8	PVR with valved conduit, rt PA replacement with 22-mm graft	Aortic root replacement with 27 Valsalva conduit, zone 2 arch replacement	S/p atrial septal defect repair	247	185	96
9	PVR with valved conduit, rt PA replacement with 22-mm graft	ECMO (decannulated on POD 5)	H/o type A repair 11 years previously	269	0	31
10	PA replacement with 29-mm homograft	No	H/o PVR and TPVR	254	0	4
11	Double-lung transplantation	Tricuspid valve repair	…	201	0	21

CABG, coronary artery bypass graft surgery; CPB, cardiopulmonary bypass; ECMO, extracorporeal membrane oxygenation; H/o, history of; lt, left; PA, pulmonary artery; POD, postoperative day; PTE, pulmonary artery thromboendoarterectomy; PVR, pulmonic valve replacement; rt, right; S/p, status post; TPVR, transcatheter pulmonic valve replacement.

Comment

PAA is a rare disease and is usually associated with congenital malformations, connective tissue diseases, idiopathic conditions, or acquired disorders, including infection, vasculitis, inflammation, trauma, or PH.¹ PAA is defined as a diameter greater than 40 mm measured in the trunk of the PA.² Pathologically, PAA classically involves degenerative changes of the elastic media, especially cystic medial necrosis. Among the risk factors, PH is particularly important, and its presence is strongly associated with prognosis. Indeed, in a large series of PA dissections, 75% to 80% of patients had PH as an underlying condition.³ PH is observed in 66% of patients with PAA.⁴ Anatomically, PAA extending beyond the bifurcation tends to involve the left PA more frequently than the right PA because of its straighter orientation, which makes it subject to higher shear force. Patients rarely have any symptoms unless there are complications such as bronchial or tracheal compression leading to cough or dyspnea, dissection, or rupture, which leads to hemoptysis.^2,4

Some studies reported that most patients had progressive dilation of the PA during the follow-up period after the diagnosis of PH. These investigators mentioned that this dilation was not related to changes in pressure. Even those patients with decreased PA pressure at follow-up were found to have a dilated PA.⁵ It has also been observed that patients with PH associated with congenital heart disease tend to develop PAA more commonly. Patients with PH associated with connective tissue disease have a smaller diameter of PA dilation.^4,6 Therefore, the etiology of PAA is an important consideration during follow-up in these patients. Treatment must be tailored to the underlying etiology.

As compared with aortic dissections, PA dissections have a higher proclivity to rupture than to extend distally because the PA media is markedly thinner than that of the aorta.³ As such, the diagnosis of PA dissection usually results in urgent surgical repair. That said, decision making and patient management are often complex, with some patients possibly requiring lung or heart-lung transplantation.

Because PAAs are rarely reported, there are no existing guidelines for their management. Some experts recommend surgical repair for patients with a PA diameter greater than 55 mm, similar to ascending aortic aneurysms,¹ to prevent dissection, rupture, airway compression, or thrombus formation. It is said that mild PA dilation, less than 55 mm, is not prognostic in patients with PH,⁵ and a PA diameter greater than 55 mm is associated with compressive complications. In patients with a PA diameter larger than 55 mm and PH, the incidence of sudden unexpected death and left main coronary artery compression was reported to be higher.⁶ On the basis of these reports, it is reasonable to recommend surgical intervention once the PA diameter exceeds 55 mm.

Additional recommendations include surgical therapy in patients with compression of adjacent structures, thrombus formation in the aneurysm, a greater than 5-mm increase in the diameter of the PA in 6 months, and the appearance of clinical symptoms.¹ Surgical repair should be recommended if a patient meets these criteria regardless of its etiology or underlying disease, to prevent the fatal complication of rupture if the patient has an acceptably low operative risk.

Our current approach conforms with these suggestions. Our recommended algorithm is shown in the Figure. However, if the patient is asymptomatic and hemodynamically stable, and the risks of the surgery outweigh the benefits, conservative management is still an option even for the patient with a large PAA. One case report noted that a 5.0 cm × 6.4 cm PAA had a 15% reduction in size after 6 months without any surgical intervention.⁷ Although these investigators did not mention whether this patient had PH, conservative management can be an option for the high-risk patient if the patient’s condition is stable.

Figure 1.

Algorithm of pulmonary artery (PA) aneurysm management. (CT, computed tomography; LHC, left-sided heart catheterization; PE, pulmonary embolism; RHC, right-sided heart catheterization; TTE, transthoracic echocardiogram.)

All PAA surgical procedures require CPB. Bicaval venous cannulation is recommended, especially when right PA replacement is needed. Aortic cross-clamp and cardiac arrest are not required, nor is cooling of the patient during CPB. However, if the patient needs a concomitant cardiac procedure or if we need a better exposure, a cross-clamp is recommended. If pulmonic valve surgery is needed at the same time, we recommend arresting the heart for better exposure.

Surgical repair of a PAA by aneurysmorrhaphy and graft replacement is relatively straightforward and can be safely performed. We believe that replacement with a Dacron graft using 4-0 polypropylene (Prolene, Ethicon) is the most common and feasible approach, but replacement with Gore-Tex (W.L. Gore & Associates), a homograft, or a xenograft can be performed.¹ If the aneurysm involves the pulmonic valve, repair or replacement should be considered to relieve right ventricular volume overload and hemodynamic burden on the vessel wall.¹ We can repair the valve by reconstructing the leaflet with the use of autologous pericardium, a valved conduit, or a valve-sparing technique.

Aneurysmorrhaphy is performed by excision of a large portion of the aneurysmal wall of the PA followed by approximation of the 2 free edges of the arterial wall. Even though aneurysmorrhaphy is a relatively simple procedure and can be performed quickly, there is a possibility of recurrent dilatation of the PAA because of the continued presence of the aneurysmal wall, especially in cases of associated PH. Therefore, aneurysmorrhaphy is not currently recommended to prevent PAA recurrence.

Postoperative anticoagulation is not necessary, similar to aortic replacement. If a patient has PAA with PH, transplantation should be considered in addition to medical treatment. Because patients with severe PH tend to have diffuse disease in the pulmonary arterioles, replacement of the main PA cannot cure the condition. In these cases, lung transplantation is the only surgical intervention that can provide a complete cure. Hence we favor aggressive and early surgical intervention because of the theoretically high risk of rupture given the thin-walled PA.

In conclusion, PAA is a rare disease, and it is sometimes fatal once it ruptures or is dissected. However, there is no guideline for management and surgical indication because of the small number of cases reported. The surgical indication needs to be considered on a case-by-case basis. However, we recommend surgical intervention once the PA diameter exceeds 55 mm or the patient has a greater than 5-mm increase in the diameter of the PA in 6 months. If the risks of surgery are thought to outweigh the benefits, conservative management is also an option even if the PA diameter is greater than 55 mm. Replacement with a Dacron graft is the most common and feasible approach, even though some patients with severe PH may require heart-lung transplantation.