Abstract
We report a case of a 56-year-old Caucasian man who presented with acute onset of substernal chest pain at rest with electrocardiogram showing diffuse ST segment depression. He had coronary artery bypass graft surgery 16 years ago with a left internal mammary artery graft to the left anterior descending artery and saphenous vein grafts to the right coronary artery (RCA) and left circumflex artery. He underwent coronary angiography, which showed two large aneurysms in the saphenous venous graft (SVG) to the RCA and a venous leak from the aneurysm. The venous leak was later confirmed with computer tomographic scan to be a fistulous communication between the SVG and the right atrium. We discuss in detail about the treatment options of SVG aneurysm.
Key words: Aneurysm, coronary artery bypass graft surgery, right atrial fistula, saphenous venous graft
INTRODUCTION
Saphenous venous graft (SVG) aneurysm is an extremely rare complication after aorto-coronary bypass surgery with fatal outcomes. Fistulous communication between the SVG with a cardiac chamber is an even more unusual entity. We report a SVG aneurysm with right atrial fistula formation, 16 years after coronary artery bypass graft surgery (CABG).
CASE REPORT
A 56-year-old Caucasian man presented from an outlying facility 2 h after acute onset of substernal chest pain at rest with diffuse ST segment depression. Sixteen years ago he had triple vessel CABG with two subsequent cardiac catheterization procedures and percutaneous coronary interventions in the last few years.
On presentation, the physical examination was unremarkable. Electrocardiogram had shown diffuse ST segment depression. Laboratory data were unremarkable, including cardiac biomarkers. He underwent cardiac catheterization with coronary and SVG angiography. It revealed severe native vessel coronary artery disease with 100% occlusion of all three native vessels. Left internal mammary artery graft to the left anterior descending artery was patent. SVG to right coronary artery (RCA) angiography revealed two aneurysms, one in the mid-body of the vein graft measuring 3 cm, followed by another 5 cm large aneurysm at the distal segment [Figure 1]. There appeared to be a leak of the contrast into the right atrium (RA) from the distal aneurysm. The aneurysm also had a posterior descending artery (PDA) runoff through the prior placed stent to the PDA at the anastomosis.
Figure 1.
(a) Saphenous venous graft angiogram showing an aneurysm in the proximal portion of the graft, and (b) another large aneurysm in the distal portion
The patient was hemodynamically stable and reviewing the coronary anatomy we did not find any lesions that were amenable to intervention. He was monitored on the cardiac floor and had further imaging studies for better visualization of the SVG leak. A poorly defined right atrial mass was also appreciated in the subcostal view of the transthoracic echocardiogram for which he underwent a transesophageal echocardiogram (TEE). TEE revealed the aneurysm measuring 5.0 cm × 5.3 cm with Doppler flow within and extending from the structure into the RA [Figure 2]. A chest computed tomographic scan with contrast revealed a partially thrombosed aneurysm measuring 2.8 cm × 3.0 cm about 3.4 cm distal to the RCA graft origin and a large aneurysm measuring 5.0 cm × 4.2 cm distal to the first aneurysm both in the SVG to the RCA. The aneurysm also demonstrated a fistulous connection to the RA [Figures 3 and Figure 4].
Figure 2.
(a) Trans esophageal echocardiogram shows a large mass, (b) adjacent to the right atrium with a fistulous connection
Figure 3.
Three-dimensional reconstruction of the computed tomography angiography showing the two aneurysms (a, b) with fistulous connection (c) to the right atrium
Figure 4.
Computed tomography angiography showing the saphenous vein graft with the two aneurysms (a, a) with fistulous connection to the right atrium. Related structures: Right ventricle, left atrium, left ventricle) are shown
The cardiovascular surgical consultation was requested regarding further management options given the above findings. Percutaneous treatment including covered stent placement across the aneurysmal segments of the SVG was discussed. After a thorough discussion with the patient, he decided conservative management at the point.
DISCUSSION
A SVG aneurysm is a very rare complication of CABG with a reported incidence of 0.07% from an estimated review of >5,500 grafts at one institution.[1]
The most likely cause of the SVG aneurysm would be degeneration of the graft from atherosclerosis causing graft dilatation.[2,3,4] SVG aneurysms may be incidental finding (32.5%) during the coronary angiography. However, patients most commonly present with chest pain/angina (46.4%), dyspnea (12.9%) and myocardial infarction (7.7%). The incidence of these aneurysms has been reported in the RCA (38%), left anterior descending (25.3%), obtuse marginal (10.9%) and left circumflex (10.5%) arteries.[5]
Complications of SVG aneurysms include fistula formation (16 case reports up until 2012, of which 9 involved the RA), compression of various cardiac chambers and great vessels, aneurysm rupture, hemothorax, and cardiac tamponade.
Management of SVG aneurysms has traditionally been surgical (58.4% of cases reported), with either aneurysmal resection or ligation, followed by bypass grafting in high-risk patients. Conservative medical management with drug optimization is the second most common treatment option (20.1% of reported cases). In the past 10 years, percutaneous intervention including coil embolization, Amplatzer vascular occlusion, and covered stent placement has been reported (15.8% of cases). In our case, we did not proceed with any percutaneous options due to the enormous size of the aneurysm and the patient decision to pursue conservative management.
Despite the very rare nature of this entity, SVG aneurysm with fistula formation carries a high morbidity and mortality risk given the high likelihood of catastrophic complications. Physicians should maintain a high index of suspicion in postCABG patients who present with new radiographic or clinical findings.
Footnotes
Source of Support: Nil
Conflict of Interest: None declared.
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