Severe Functional Tricuspid Stenosis Secondary to a Giant Saphenous Vein Bypass Graft Aneurysm.

A 75-year-old man presented with dyspnea requiring home oxygen, on a background of partial colectomy for colon cancer, chronic renal failure, and coronary artery bypass graft surgery in 1978 (left internal mammary artery to left anterior descending graft and saphenous vein grafts [SVG] to the right coronary artery [RCA] and left circumflex artery). Clinically, he had jugular venous distension and bibasal crepitations, without overt ascites or peripheral edema. Chest x-ray demonstrated remote postoperative changes, cardiomegaly, mild pericardial calcification, and other radiographic findings of congestive heart failure, without apparent mediastinal mass (Figure 1). However, echocardiography revealed a large (9.4×8.7 cm), apparently extracardiac, mass compressing the right ventricle with severe functional tricuspid stenosis (mean gradient, 10 mm Hg) and turbulence of forward transtricuspid flow on color Doppler imaging (Figures 2A, 2B, and 3; Movie IA and IB in the online-only Data Supplement). Noncontrast cardiac MRI revealed a large (10.9×7.4×6.5 cm), relatively homogenous structure adjacent to the atrioventricular groove anteriorly, which was compressing the right heart and obstructing the tricuspid valve. The mass was distinct from adipose tissue, well circumscribed by overlying pericardium, and had no invasive characteristics. Cine imaging demonstrated flow within the mass. The structure location and characteristics were consistent with a partially thrombosed SVG aneurysm (Figure 4; Movie II in the online-only Data Supplement). Coronary angiography showed a proximally patent SVG to RCA, which terminated in a 14-mm focal aneurysm with absence of distal filling of the native RCA. Contrast was noted washing out of the aneurysm into a large, partially calcified, adjacent pseudoaneurysm (Figure 5; Movie III in the onlineonly Data Supplement). At surgery, a large 10-cm pseudoaneurysm, arising from an aneurysmal SVG to the RCA, was found compressing the right heart. The pseudoaneurysm was opened with removal of extensive organized thrombus (Figure 6). The proximal graft and distal native RCA were identified and both ostia were oversewn, enabling resection of the aneurysmal SVG graft (Figure 7). Redo SVG bypass was then performed. The patient made an uneventful recovery with significant improvement in his presenting symptoms. Postoperative echocardiography demonstrated normal tricuspid valve morphology, with mild (1–2+) tricuspid regurgitation and no intrinsic valvular or residual functional stenosis (Figure 8A and 8B; Movie IVA and IVB in the online-only Data Supplement). SVG aneurysms and pseudoaneurysms are rare and typically late complications of coronary artery bypass graft surgery. Incidence is reported at 0.07% with a mean time to presentation of 13 years. The prevalence of true aneurysms (SVG-A) is twice that of pseudoaneurysms (SVG-PA), which are typically larger. Chest pain is typically the reason for presentation, especially in subjects with SVG-PA, because a large proportion of subjects with SVG-A are asymptomatic and diagnosed incidentally on chest x-ray. Chronic aneurysm development is generally attributed to vein graft atherosclerotic degeneration, endothelial changes, or increased wall stress from arterial pressures. Acutely, surgical technical failure or anastomosis disruption attributable to infection can result in SVG-PA. As in this case, aneurysmal grafts are most commonly anastomosed to the RCA, largely related to preferential use of arterial grafts for the left coronary system. Complications of SVG-A/SVG-PA include compression of adjacent vascular and cardiac structures, along with rupture, embolization of mural thrombus, and fistula formation. Accurate identification of SVG-A/SVG-PA is particularly important, given the high likelihood of symptom reversal with surgical resection. This case of giant SVG-A causing symptomatic, functional tricuspid stenosis illustrates the benefits of multimodality cardiac imaging. In particular, cardiac MRI provides tissue characterization, assessment of aneurysm dimensions, relationship with surrounding structures, patency of grafts/coronaries, and data regarding ventricular and valvular function, which may be relevant for redo cardiac surgery. Although coronary angiography remains important to determine graft patency and aneurysm location, it may understimate SVG-A size because of intramural mural thrombus or poor appreciation of an associated SVG-PA. Surgical graft ligation and aneurysm resection with or without redo bypass surgery has been the typical treatment, especially when surrounding structures are intimately involved. However,