Article Text
Summary
Aneurysms of the pulmonary artery are very rare. Here, the authors report the clinical scenario of a middle aged diabetic who presented with suppurative cardiac tamponade that was complicated by mycotic aneurysm of the pulmonary artery. In addition to the clinical presentation, aetiology, diagnostic modalities and therapeutic options are discussed.
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Background
This case represents clinical presentation of a pulmonary artery aneurysm. The patient presented with suppurative pericarditis and bilateral pneumonia. His hospital course was complicated, and could not be weaned from artificial ventilation. His diabetes mellitus and the prolonged courses of multiple antibiotics exposed him to the risk of fungal infection. The patient’s acute illness and pulmonary artery aneurysm were challenging. The lack of guidelines, and the few reported cases of such aneurysms led us to report it.
Case presentation
A 48-year-old Bahraini man came to the emergency department with progressive shortness of breath that had lasted for 5 weeks. This symptom was associated with intermittent fever, productive cough, anorexia and chest pain. He described the onset of his symptoms after his return from pilgrimage (holy trip to Makkah) 2 months prior. He was subjected to multiple courses of antibiotics without improvement. Of particular note, he was diabetic and a heavy smoker.
On admission, his body temperature was 38.8°C, his heart rate was 125 beats/min and his blood pressure was 110/65 mm Hg.
Upon arrival at the emergency room, he was electively intubated due to his severe shortness of breath and marked cyanosis. His jugular venous pressure was elevated, and his face was plethoric. Cardiac sounds were muffled, and fine inspiratory crackles were noted at his lung bases.
Investigations
His complete blood count showed haemoglobin 17.5 g/dl, a platelet count of 178×109 and white cell count of 7.5×109, with polymorphs ~81% and lymphocytes at 19%. Room air arterial gas showed PaO2=60.9 mm Hg, PaCO2=86.2 mm Hg and pH=7.22.
A chest radiograph revealed a flask-shaped heart with an increased cardiothoracic ratio. His electrocardiogram displayed electrical alternans with peaked P waves. Additionally, echocardiography was performed, which showed features of pericardial tamponade and normal ejection fraction, and his pulmonary artery systolic pressure was calculated to be 27 mm Hg. He underwent emergency pericardiocentesis. The catheter was left in place, and it drained up to 1.5 l of turbid yellowish fluid over 48 h. Analysis of the fluid revealed a white cell count of 80 000 with 91% polymorphs and 9% lymphocytes. The fluid was exudative, with 40 g/l protein and ~2275 u/l lactic dehydrogenase, but culturing failed to grow any organism.
Treatment
The initial clinical impression was purulent pericardities with adult respiratory distress syndrome. The patient was started on parenteral antibiotics after full septic screening.
The patient remained pyrexic with progressive hypoxia and an inability to wean from artificial ventilation. His inspired oxygen remained high, and he required high ventilator pressure support.
He underwent bedside bronchoscopy with biopsy, but the procedure could not be completed because the left bronchus was occluded by an external pulsating mass that was not biopsied.
A CT scan of his chest with contrast revealed aneurysmal dilatation of the pulmonary trunk and its main branches. The bifurcation and left pulmonary artery were approximately 5 cm in diameter, and the right pulmonary artery was 3 cm in diameter (figure 1).
A deep bronchial wash culture grew Candida albicans. Antifungal therapy (intravenous fluconazole) was initiated. Pulmonary angiogram findings were identical to those of the CT scan (figure 2).
Outcome and follow-up
He became afebrile 48 h after starting antifungal therapy and was extubated after 7 days. He remained in the hospital for 4 weeks and received active rehabilitation in addition to a full course of antifungal therapy. The initial high uptake at the aneurysm site during a gallium scan subsided at the 12-week follow-up study (figures 3 and 4).
His condition has been discussed in the cardiothoracic meeting, and conservative therapy was agreed upon provided close follow-up.
He was discharged to his home in stable clinical condition with a special emphasis on controlling his diabetes and quitting smoking. Upon serial follow-up, he was asymptomatic and his pulmonary artery aneurysm has not progressed in size over the last 2 years.
Discussion
Aneurysms of the pulmonary artery are considered to be rare in comparison to those of the aorta or intracranial vessels.1 The estimated incidence of main pulmonary artery aneurysm is 1 in 14 000 autopsies.2
The causes of pulmonary artery aneurysms vary from congenital heart disease-related (e.g., atrial and ventricular septal defects), infections, trauma, vasculitis and secondary to pulmonary hypertension.3 4
Mycotic pulmonary aneurysms are commonly caused by suppurative bacterial infections, such staphylococci and streptococci, but treponemal, mycobacterial and rarely fungi (including Candida and Aspergilli) have been reported.1
The proposed mechanisms for infection dissemination include direct involvement of pulmonary artery from an adjacent focus, such as tuberculosis of the lungs.3 Infection of the vasa vasorum with subsequent arterial wall ischemia (as in syphilis), direct extension into the vessel wall from an intraluminal septic thromboembolus, or haematogenous spread (as in bacterial endocarditits) are alternative mechanisms of infection dissemination.3
Direct spread of the infection from the adjacent infected pericardium is the most likely scenario in our patient. Imaging is the main diagnostic modality. Although pulmonary angiography was previously the gold standard diagnostic modality, CT and MRI have recently become important alternatives. In our patient, the CT and pulmonary angiograms revealed saccular dilation of his pulmonary trunk along with the bifurcation.5 During bronchoscopy, it can mimic endobronchial neoplasm, but being pulsatile precludes its biopsy to avoid catastrophic bleeding.6
The initial positive gallium nuclear scan at the site of aneurysm, which subsided at subsequent study after 12 weeks, supports the fact that the aneurysm was infective in origin.7
The management of pulmonary artery aneurysm is a major challenge that lacks clear guidelines addressing the surgical indications. The proposed surgical interventions include aneurysmectomy, lobectomy, aneurysmorrhaphy and banding.8 9
Low pressure pulmonary artery aneurysms stands against future risk of rupture and dissection. Furthermore, preserved right ventricle systolic function and the absence of pulmonary valve regurgitations justify conservative medical therapy. This includes infection eradication with subsequent clinically and radiologically guided follow-up.10 11
Learning points
▶ The low pressure pulmonary artery aneurysms are at lower risk of dissection and rupture than the high pressure ones.
▶ Prolonged courses of antibiotics and diabetes mellitus are risk factors for fungal infections.
▶ Pulsating intrabronchial masses should not be biopsied.
Footnotes
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Competing interests None.
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Patient consent Obtained.