Anterior Descending Coronary Artery Pseudoaneurysm in an 85-Year-Old Male Hemodialysis Patient: A Surgical Case Report

Background

Coronary artery pseudoaneurysm is extremely rare and can lead to myocardial ischemia, acute myocardial infarction, acute coronary artery rupture, and death due to cardiac tamponade if not treated appropriately [1]. Here, we report an extremely rare case of coronary artery pseudoaneurysm in a hemodialysis patient who underwent aneurysmectomy and coronary artery bypass grafting (CABG). In this case, the aneurysm was thought to have been caused by vessel wall rupture due to atherosclerotic degeneration of the coronary artery. Since this is an extremely rare cause of coronary artery pseudoaneurysm, we report this case with a review of the literature.

Case Report

An 85-year-old man presented to the emergency room with fever and chest pain and was admitted to the cardiology department for a urinary tract infection and acute coronary syndrome.

He had a history of hypertension and type 2 diabetes mellitus. He had previously undergone emergency percutaneous coronary intervention (PCI) for the left anterior descending artery (LAD) for acute coronary syndrome 9 years ago and had been undergoing hemodialysis for the last 4 years due to diabetic nephropathy.

His urinary tract infection was treated with intravenous ampicillin and sulbactam at a dose of 3 g per day for 8 days from the day of admission and showed improvement. Subsequently, diarrhea was observed. Clostridium enteritis was diagnosed, and the patient was treated with oral vancomycin at a dose of 500 mg per day for another 10 days. On day 21 of admission, when the infection was controlled, coronary angiography was performed, which revealed a pseudoaneurysm proximal to the LAD stent (Figure 1D). Coronary computed tomography (CT) showed a pseudoaneurysm measuring 28×20 mm (Figure 1B, 1C). Consequently, the patient was referred to our department for further surgical treatment.

Surgery was performed under general anesthesia. After median sternotomy and pericardiotomy were performed, inspection of the pericardial sac’s interior revealed that the pseudoaneurysm wall was adherent to the pericardium (Figure 2A). After establishing cardiopulmonary bypass, the patient experienced cardiac arrest. First, the saphenous vein graft was anastomosed end-to-side to the distal end of the LAD. Subsequently, the pseudoaneurysm wall was opened, and the inside of the aneurysm was examined, which revealed an intramural thrombus in the aneurysm. The intima of the coronary artery was highly calcified and completely ruptured on the proximal side of the pseudoaneurysm (Figure 2B, 2C). Since repair with preservation of the coronary artery was impossible, the pseudoaneurysm was removed.

As the highly calcified intima was difficult to simply ligate, proximal and distal endarterectomies were performed to the extent possible. A portion of the stent was removed during the distal endarterectomy. Both proximal and distal closures were performed with a 3-0 monofilament felt, such that the myocardium was pulled close to the mass. The pseudoaneurysm was then closed with a band-felt and 4-0 monofilament (Figure 2D). Cardioplegia was induced to confirm the absence of bleeding. Finally, after proximal anastomosis of the saphenous vein graft with the ascending aorta, the patient was withdrawn from cardiopulmonary bypass.

Histopathology showed partial swelling of the coronary artery wall, edematous fibrosis in the surrounding fatty tissue, and mild lymphocytic infiltration, consistent with a pseudoaneurysm (Figure 3A, 3B). There was no bacterial or neutrophilic infiltration or any obvious signs of infection. Two months postoperatively, coronary angiography CT showed patency of the bypass graft without pseudoaneurysm recurrence (Figure 4A, 4B). Three months postoperatively, the patient was transferred to a convalescent hospital.

Discussion

Coronary artery pseudoaneurysm is extremely rare; however, its exact incidence is unknown [1]. A pseudoaneurysm is an extravascular hematoma that communicates with an intravascular lumen. The vessel wall is ruptured, and the external wall of the aneurysmal sac consists only of the outer arterial layer, perivascular tissue, or thrombus [2]. From this case, we can learn that atherosclerotic changes can lead to the formation of coronary artery pseudoaneurysms in elderly hemodialysis patients.

The most common cause of coronary artery pseudoaneurysm is coronary artery dissection or perforation induced by catheterization or coronary artery bypass surgery [1,3,4]. Other cases have been associated with infections, pregnancy, and blunt trauma [5]. It can also occur as a complication of collagen diseases, such as Behçet’s disease and anti-phospholipid antibody syndrome [6,7]. In catheter interventions, factors such as the type of catheter used, inappropriate placement, mal-position of the stent, dissection of the edge of the stent, rapid injection of contrast agent, and simple balloon angioplasty can cause dissection or perforation of the artery and result in pseudoaneurysm [8–10]. The frequency of pseudoaneurysms associated with PCI is reported to be 0.3–6%, usually occurring 6–9 months after PCI [11]. Although this patient also had a history of PCI for LAD, because PCI had been performed 9 years earlier, pseudoaneurysm associated with PCI was ruled out. Plain CT on admission showed no findings of a pseudoaneurysm (Figure 1A), and intraoperative findings indicated that the proximal side of the stent was distal to the site of intimal disruption. Intraoperative findings showed severe calcification of the coronary intima and its disruption, suggesting that atherosclerosis was the likely cause of pseudoaneurysm in this case.

This patient was elderly and had a history of hemodialysis. Circumferential calcification of the coronary arteries often occurs in hemodialysis patients with chronic renal failure [12]. If a non-calcified portion of the wall is present, there may be a risk of physical damage due to changes in vascular elasticity at the borders of the wall. The histopathological findings in this case also support the possibility of physical damage, as part of the external elastic lamina of the coronary artery disappeared with no signs of infection.

The natural history of pseudoaneurysm is poorly understood. The pathophysiology of pseudoaneurysm is believed to include inflammation, endothelial dysfunction, and platelet aggregation. Therefore, thrombosis may be induced by distal embolization, leading to myocardial infarction [1]. The risk of pseudoaneurysm rupture has also been reported in patients over 40 years of age with angina pectoris, infective endocarditis, congestive heart failure, and distal embolization, which, if ruptured, can result in death from cardiac tamponade [8]. Therefore, prompt and appropriate treatment of patients with angina symptoms, such as chest pain, is essential.

Currently, no standard treatment exists for coronary artery pseudoaneurysm. If the pseudoaneurysm is small, anticoagulation is the treatment of choice to prevent myocardial ischemia due to thromboembolism. If the pseudoaneurysm is large, there is a possibility of rupture, necessitating endovascular treatment, including coronary angioplasty with a covered stent or coil embolization. Surgical procedures include removal of the pseudo-aneurysm with simultaneous CABG [13,14], the interposition of a graft in situ after pseudoaneurysm resection [15,16], and coronary patch formation [17,18]. Since endovascular treatment was considered difficult in this case due to severe coronary artery calcification, we selected surgical treatment consisting of patch repair of the LAD and CABG. To ensure that the pseudoaneurysm was treated, the surgical procedure was performed during cardiac arrest using cardiopulmonary bypass.

Intraoperatively, we opened the pseudoaneurysm and found a highly calcified intima and its rupture; therefore, we judged coronary angioplasty to be difficult and decided to remove the pseudoaneurysm. Since infection was also a potentially concerning cause of the pseudoaneurysm, stent removal in the LAD was performed concurrently with endarterectomy. After accomplishing CABG to the LAD, the patient was weaned off cardiopulmonary bypass. Postoperatively, the patient’s chest pain symptoms resolved, and contrast-enhanced CT showed that the pseudoaneurysm had disappeared and that the graft had good patency.

Conclusions

In this case, atherosclerotic degeneration of the coronary artery was believed to cause arterial wall rupture, resulting in the formation of the pseudoaneurysm. Although coronary artery pseudoaneurysm is extremely rare, the possibility of coronary pseudoaneurysm due to severe calcification of the coronary arteries should be considered in patients undergoing hemodialysis.