Case Description
A twenty-five year old man presented to the emergency department with chest pain and was found to have a spontaneous pneumothorax on chest x-ray. His past medical history was significant for prior bilateral spontaneous pneumothoraces in 2012 and 2013 treated with tube thoracostomy and uniportal VATS pleurodesis. He was admitted overnight for observation and serial x-rays. An irregular contour of the left superior heart border was noted on plain films, which prompted review of imaging from the patient’s previous hospitalizations in 2012 and 2013. A similar abnormal cardiac silhouette was noted at that time. The patient did undergo a non-contrast CT scan in 2013 however no definite abnormality was noted, likely due to lack of contrast. He did not obtain additional imaging in the interim. A CT scan with contrast was subsequently obtained which revealed a 5.4 x 6.6 x 6.3 cm anterior mediastinal mass with heterogeneous attenuation superior to the left ventricle. Initial workup did include germ cell tumor markers and testicular ultrasound to rule out malignancy. His apical pneumothorax remained stable without need for additional intervention and he was discharged home for continued outpatient workup. Because of concern for potential invasion of the heart, a cardiac gated MRI was obtained which demonstrated that the cystic mass was exhibiting mass effect on the anterior wall of the left ventricle, the aortic root and the main pulmonary artery (Figure 1). It appeared to be in communication with the vasculature however the origin was unclear on this study. Subsequent coronary CT angiography demonstrated a diffusely dilated LAD measuring 7mm x 6mm which was contiguous with the superior aspect of the mass. (Figure 2a) It was again characterized as a separate entity from the left ventricular wall, ruling out LV aneurysm. The aneurysm was confirmed to arise from the proximal-mid LAD after the takeoff of a large septal perforator. The distal/apical LAD was not visualized. A dominant right coronary artery appeared unremarkable, and no additional coronary anomalies were observed on subsequent coronary angiography (Figure 2b). A planned surgical approach was discussed with the patient including aneurysmal ligation and coronary artery bypass bypass, and he elected to proceed. Operative intervention was performed with a median sternotomy and myocardial arrest. A large aneurysm arising from the proximal LAD was identified (Figure 3). After myocardial arrest, the aneurysm was opened in its entirety from its origin at the proximal LAD down to the base, taking care to preserve a large septal perforator and smaller collateral vessels. The LAD was ligated and the remainder of the aneurysm sac was dissected off the heart exposing raw myocardium. Upon careful inspection, there was no continuation of the distal LAD that would be an appropriate target for bypass grafting or patch repair. The patient was weaned off cardiopulmonary bypass without much difficulty and discharged home on post-operative day 3 without any perioperative complications.