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.