Large saphenous venous graft aneurysm mimicking atypical mediastinal mass

Background. Saphenous venous graft (SVG) aneurysm is a very rare but potentially fatal complication of the coronary artery bypass surgery. Case report. We reported a case of 72-year-old man admitted to hospital because of atypical chest pain related to body motions in horizontal position, especially to the left side. Pain was followed by dispnea, palpitations, fatigue, cough, yellow sputum expectorations, as well as elevated temperature. He had had coronary artery bypass grafting (CABG) surgery with saphenous vein grafts (SVGs) to the left anterior descending artery (LAD) and right coronary artery (RCA) 27 years earlier. Chest X-ray revealed a poor-defined shadow in the region of the right atrium. A transthoracic echocardiogram revealed an atypical tumorous mediastinal mass near the right atrium and right ventricle that seemed partially calcified on transesophaeal echocardiography (TEE). CT scan confirmed an atypical mediastinal mass in contact with the right ventricle that might be a right ventricle aneurysm, pericardial cyst or SVG aneurysm. Coronary angiography was performed subsequently and it revealed a big saphenous venous graft aneurysm originating from the previous venous graft to the RCA. The aneurysm was resected and a new bypass graft was placed. Histopathology confirmed a true aneurysm of the venous graft. Conclusion. Although SVG aneurysm is a very rare complication of CABG surgery, patients presenting with atypical hilar or mediastinal mass following CABG should always be evaluated firstly for existence of this cardiosurgical complication.


Introduction
Saphenous venous graft (SVG) aneurysm is a very rare but potentially fatal complication of coronary artery bypass surgery (CABG) with a wide variation in clinical presentations ranging from recurrent atypical chest pain to a sudden cardiac death.Aneurysms of saphenous vein grafts to coronary arteries were first reported in 1975.Since that time only a few cases have been described in medical literature 1, 2 .We reported a case of saphenous venous graft aneurysm diagnosed 27 years after coronary artery bypass surgery, presented with atypical chest pain and X-ray shadow in the paracardial right position.

Case report
In April 2006, a 72-year-old man was admitted to the hospital because of atypical chest pain followed by fatigue, dispnea, elevated blood temperature, coughing and yellow sputum expectorations.Chest pain was related to body motions in horizontal position, especially on the left side.The patient had been submitted to coronary artery bypass surgery with SVG to the left anterior descending artery (LAD) and to the right coronary artery (RCA) 27 years earlier.His medical history showed hypertension for 30 years and atrial fibrillation for eight years; he had been receiving oral anticoagulant therapy.Three years before this hospitalization he had been submitted aortofemoral bypass graft surgery and preoperative echocardiogram, without any atypical findings.
On admission, a grade III/IV systolic murmur was audible at the right side of the second intercostals space.Physical examination revealed lower breathing at the basal part of the right lung and inspiratory crepitant hales at the basal part of the left lung.ECG was without any ischemic changes.Chest radiography revealed an abnormal right-sided cardiac contour.A transthoracic echocardiogram revealed an atypical mediastinal mass in close contact with the right atrium and right ventricle, of 70 × 60 mm (Figure 1).Transesophageal echocardiography (TEE) confirmed atypical formation of 70 × 50 mm, in close contact to the right atrium, partially calcified, without causing pathological intracardial gradient.After TEE the origin of this mass yet was not clear, thus thoracal CT scan was performed.CT scan confirmed the existence of an oval atypical mediastinal mass of the largest dimensions of 71 × 73 mm, in contact with the right ventricle and right atrium (Figure 2).The right ventricle aneurysm with thrombotic masses was discussed as a more likely diagnosis, as well as tumorous mediastinal mass, pericardial cyst and pericardial tumor.Coronary angiography finally resolved the problem, revealing a big saphenous venous graft aneurysm in convolutes, originating from the previous venous graft to the RCA (Figure 3).Both grafts (RCA and LAD) were patent.Native RCA was occluded before graft insertion, while LAD and circumflex coronary artery (ACx) had nonsignificant atherosclerotic changes.The surgery was done on the beating heart.During the surgery it could be seen that the graft aneurysm was partially filled with thrombotic debris, but patent (Figure 4).Ligation of graft aneu- rysm was followed by acute ECG elevation on monitor, and after a fast resection and successful placement of the new venous graft ECG was completely normalized.Histopathology confirmed a true aneurysm of the venous graft.The patient recovered successfully and control echocardiography showed normal cardiac structure (Figure 5).

Fig. 5 -Control echocardiography showed normal cardiac structure Discussion
We presented a patient who developed a large aneurysm of SVG to the right coronary artery 27 years after the coronary artery surgery.Aneurysms of vein grafts are late complications of CABG surgery, rare, but potentially fatal.Reported time of development of these complications can vary from 10-20 years postoperatively, but in this case it was even longer 1, 2 .Almost all of the patients with a big SVG aneurysm have atypical chest pains.In all the reported cases anamnesis, physical examination and non-regular chest radiography were not enough to reveal the diagnosis of SVG aneurysm.In this case, as well as in the majority of reported cases, additional CT scan and echocardiography were necessary in order to find out the diagnosis, but the final solution was found out after coronarography.Most of the reported SVG aneurysms were described during echocardiography as a mass of unknown origin in close contact to heart, especially to right cardiac structures -right atrium, right ventricle and pulmonary artery outflow tract [3][4][5] .In this case only coronary angiography revealed the true origin of atypical mediastinal mass previously seen by CT scan and echocardiography.
Most frequent lesions in venous grafts, found by histopathological analysis in patients with previous heart revascularization were lesions of the endothelium, causing thrombosis formation and a partial or complete lumen occlusion.In this case graft aneurysm was partially filled with thrombotic debris, but patent 6,7 .
Options for SVG treatment are still discussed.There have been only a few reported cases managed with percutaneous endovascular procedures 8,9 .However, most cases were successfully resolved by surgical ligation of the graft or resection of aneurysm by the replacement of a new conduit in the native coronary artery 10,11 .Early surgery is a treatment of choice, preventing fatal graft rupture and potential embolization of muralthrombi to distal coronary artery segments 12 .In this case, although graft aneurysm was partially filled with thrombotic debris, it was patent and ST elevation that was seen immediately after its ligation is a marker of preserved function.

Conclusion
Although SVG aneurysm is a very rare complication of CABG surgery, patients presenting with atypical hilar or mediastinal mass following CABG should always be evaluated firstly for the existence of this cardiosurgical complication, no matter how long ago the surgery had been done.