PH Grand Rounds: Giant Pulmonary Artery Aneurysm and Severe Multifactorial Pulmonary Hypertension: A Case Report

PRESENTATION

A 63 year-old morbidly obese female with chronic hypercarbic and hypoxic respiratory failure was referred to our program for severe pulmonary hypertension (PH) identified on right heart catheterization (RHC).

On presentation, she complained of increasing shortness of breath on exertion, in setting of PH directed therapy with macitentan and sildenafil prescribed 3 years before. She had initially improved on this regimen and supplemental oxygen. The patient remained compliant with a continuous positive airway pressure device and supplemental oxygen for obstructive sleep apnea. In clinic, vital signs were unremarkable; she had normal O2 saturation on 3 L/min supplemental oxygen. Physical exam revealed no jugular venous distention or right ventricular heave. S1 and S2 were equal; lungs were clear to auscultation bilaterally. Trace lower extremity edema was present. A comprehensive evaluation for pulmonary arterial hypertension (PAH) excluded connective tissue disease and other Group 1 etiologies. A severe restrictive ventilatory defect and impairment of diffusing capacity were reported on pulmonary function testing. Echocardiogram revealed left ventricular ejection fraction of 80%, normal right ventricular size and function, moderate to severe pulmonic regurgitation, and a previously unreported large pulmonary artery aneurysm (PAA), measuring over 7 cm. Computed tomography angiography of the chest confirmed a main pulmonary artery aneurysm of 7.4 cm at its greatest dimension (Figures 1 and 2). Serologies for associated infection (syphilis and tuberculosis) were negative. A repeat RHC demonstrated elevated mean pulmonary arterial pressure of 48 mm Hg, pulmonary capillary wedge pressure 21 mm Hg, pulmonary vascular resistance 5.38 Wood units, and Fick cardiac index 2.49 L/min/m². Diuresis was intensified. Patient was referred to an academic center for consideration of surgical management. Her pulmonary function tests and functional status excluded her from surgery. Pulmonary hypertension directed therapy was reconsidered; macitentan was discontinued in view of pulmonary vascular congestion, while sildenafil was continued.

View Figure

• Download as Powerpoint
• Download Figure

View Figure

• Download as Powerpoint
• Download Figure

Right heart catheterization repeated 10 months later revealed worsening hemodynamics: mean pulmonary arterial pressure 50 mm Hg, pulmonary capillary wedge pressure 14 mm Hg, pulmonary vascular resistance 7.8 Wood units, and Fick cardiac index 2.34 mL/min/m². Selexipag was added and titrated to maximal tolerated dose. Exertional dyspnea, peripheral swelling, and oxygen requirement have improved with continued directed PH therapy. The PAA has remained stable in size on serial computed tomography pulmonary angiography for 2 years.

DISCUSSION

A giant PAA with coexistent severe multifactorial PH represents a management challenge. Pulmonary artery aneurysm is an unusual defect that can be seen in patients with PH. Pulmonary artery aneurysms are defined by vessel diameter greater than 4 cm and are relatively rare, with a reported incidence of 0.0073%.1 There is a slight female predominance, with peaks of occurrence in the third and sixth decades.2 Congenital heart disease with left-to-right shunt accounts for more than half of PAA cases. The remainder are associated with connective tissue disease (vasculitis), infections (including syphilis and tuberculosis), PAH, chronic pulmonary thromboembolic disease, pulmonary vascular neoplasm, and cystic medial necrosis. Of note, prior studies have reported a PAA prevalence of 1.3% to 24% in PAH.3 However, a recent retrospective cohort study reported 38% of PAH patients having evidence of aneurysmal dilation of one of the proximal pulmonary arteries.4

Pulmonary artery aneurysms are often asymptomatic but can present with heart failure symptoms of dyspnea, chest pain, and cough due to mass effect.5 The mechanism by which PA dilation progresses in PH patients with a PAA remains unclear.4 Several small studies have suggested PH and PAAs progress independently.6,7

Other literature suggests that increased pulmonary pressures superimposed on large-radius aneurysms may increase parietal wall stress, causing intimal tearing and increasing risk for PA dissection or rupture.8,9 Reducing hemodynamic stress on the PA wall may prevent progression of PAA dilation.10

Surgery is the treatment of choice in selected patients, but there is not consensus on a vessel diameter threshold or growth rate for surgery.5,8 One report suggested operating at a diameter greater than 5.5 cm, based on the guidelines for aortic disease, or with an increase in diameter of greater than 0.5 cm in 6 months.5 Our patient was not a surgical candidate due to comorbid chronic respiratory failure complicated by coexistent severe PH. Also, a vascular lesion involving a proximal pulmonary artery and more distal arterioles would not be corrected by surgery.5,11 Therefore, PAH targeted therapy was continued, given RHC data that met the hemodynamic definition of PAH, as well as for potential salutary effect of reduction of shear force on this patient's giant, inoperable PAA.

Our case describes challenges in management of a giant PAA complicated by severe multifactorial PH. Though the patient's PH had characteristics of Group 1 and Group 3 disease, in this case, management with PH directed therapy was associated with decreased oxygen requirement and improved exertional tolerance. The Sixth World Symposium on Pulmonary Hypertension (WSPH) does not currently recognize an indication for PH directed therapy in patients with combined Group 1 and 3 disease.

In conclusion, PH directed medical therapy might be a useful adjunct to management of inoperable PAAs complicated by coexisting PH.

KEY POINTS

• A pulmonary artery aneurysm (PAA) is comparatively rare, with reported incidence of 0.0073% in the general population.

• Congenital heart disease, vasculitis, and infection (mycotic) are recognized etiologies for PAAs. An association of PAAs with pulmonary arterial hypertension is more common than previously thought.

• There is no consensus as to what threshold PAA diameter requires operative intervention. Literature suggests surgical intervention at a diameter greater than 5.5 cm based on guidelines for aortic disease.

• A beneficial effect of PH directed therapy might be seen in management of cases of combined Group 1 and 3 disease, as in this patient with coexistent PAA. However, this is not currently a recognized indication for PH directed therapy.