Compression of the Left Main Bronchus Between a Descending Thoracic Aortic Aneurysm and an Enlarged Right Pulmonary Artery: Discussion
The lung beyond the compression was filled with fluid and bronchiectatic. Also noted were calcified pleural plaques and patchy right upper lobe pneumonia, which had not been apparent on the chest radiograph obtained on admission.
A thoracic surgical opinion was obtained. Buy birth control pills online more A pneumonectomy was considered but the the risks of doing the procedure were judged to be prohibitive. First, a pneumonectomy would be technically difficult in this patient because of pre-existing pleural disease and the large vascular structures near the hilum. Second, the patient had poor physiologic reserve. Third, there was active ongoing infection of both lungs. His pneumonia was treated with cefuroxime 750 mg IV every 8 hours and metronidazole 500 mg IV every 8 hours pending sputum cultures and bronchodilator therapy was maximized in an attempt to clear his right lung of infection and wean him from the ventilator. This approach was unsuccessful. After 2 weeks of aggressive medical therapy, mechanical ventilation was discontinued because of continued clinical deterioration.
It is well recognized that ascending and transverse aortic arch aneurysms can cause tracheal or main bronchial compression. In contrast, aneurysms of the descending thoracic aorta though common, only rarely cause tracheobronchial compression.’ This case is unique in that the right pulmonary artery played a significant role in compressing the left mainstem bronchus. Not only was the right pulmonary artery markedly enlarged (32 mm; upper limit of normal =24.3 mm), but the presence of pulmonary hypertension made it relatively uncompressable. Pulmonary hypertension was not confirmed, as right heart catheterization was not performed, but such diffuse enlargement of the proximal pulmonary vasculature (left pulmonary artery, 30 mm, upper limit of normal =28.0 mm; main pulmonary trunk, 37 mm, upper limit of normal =28.6 mm) is highly specific for pulmonary hypertension.
Because an autopsy was not done, the mechanism responsible for occlusion of the bronchus is not known. Possibilities include (1) slow evolution of both right pulmonary artery and descending aortic dilatation or (2) an acute on chronic event such as bleeding into the aneurysm wall, or an increase in pulmonary artery pressure and diameter from relatively worse gas exchange caused by acute infection.
This case also presented a challenging management problem: a descending thoracic aortic aneurysm at risk for rupture and a severely infected and bronchiectatic left lung. The surgical options of pneumonectomy and of aneurysmectomy were considered but were rejected in the acute setting because the risk of doing either procedure was thought to be prohibitive. Instead, a conservative approach was adopted—the rationale being that correction of the gas exchange abnormality and treatment of infection would relieve hypoxic vasoconstriction and reduced pulmonary artery pressure. The latter, it was reasoned, would permit the left-main bronchus to open, allowing drainage of the left lung. If this approach had been successful, the patient could have been considered for definitive surgical treatment.
Category: Respiratory Symptoms
Tags: aortic aneurysm, pulmonary hypertension, tracheobronchial compression