Background

Acute mesenteric ischemia (AMI) is a rare but lethal complication after cardiac surgery. The incidence ranges from 0.4 to 2.9% and is associated with higher mortality (67–100%) [1, 2]. The aetiology of AMI includes superior mesenteric artery embolization, mesenteric venous thrombotic occlusion, and splanchnic vasoconstriction [3]. AMI due to contained rupture of the superior mesenteric artery is very rare following cardiac surgery. We report the case of a patient who developed AMI following double valve replacement due to superior mesenteric artery pseudoaneurysm.

Case report

A 25-year-old male underwent double valve replacement surgery at our hospital. Intraoperatively, there was healed vegetation on the aortic leaflet. During surgery, mild hypothermia and blood flow were maintained with a cardiac index of 2.2 L/min. The total bypass time was 110 min, and the surgery was uneventful. Postoperatively, the patient was extubated within 24 h, and he was maintaining good hemodynamics. The postoperative course was uneventful, with no prolonged intensive care unit (ICU) stay and minimal inotropic support. On postoperative day 10, the patient experienced diffuse abdominal pain with abdominal distention and vomiting. Subsequent laboratory findings showed anaemia with the haemoglobin (Hb) of 7 mg/dl, leucocytosis, and raised amylase and lipase levels, suggesting the possibility of acute pancreatitis. To confirm and further delineate the diagnosis, a multidetector computed tomography scan of abdomen was done, which showed a large irregular saccular pseudoaneurysm with a size of 49.5×45.5×59.6 mm after superior mesenteric artery (SMA) origin (Fig. 1); it also showed another 15×13 mm small true aneurysm arising from the jejunal branch of the SMA (Fig. 2). The study revealed fluid-filled dilated few jejunal and ilieal loops and an ascending colon, with subsequent wall enhancement suggesting bowel ischemia and sub-acute intestinal obstruction (Fig. 3). The study also revealed moderate ascites and clots in the pelvis. A gastrosurgical opinion was sought immediately, and the patient was taken for surgical exploration. The patient underwent a successful exploratory laparotomy with resection of the gangrenous small bowel, hemicolectomy, jejulostomy, and ligation of the large pseudoaneurysm of SMA. Histopathologic report showed extensive mucosal necrosis, transmural inflammation, and haemorrhage. The mesenteric blood vessels were congested and thrombosed (Fig. 4) Post exploration, the patient recovered well and maintained good hemodynamics. The patient was put on oral feeds on postoperative day 4, when jejunostomy started functioning. On postoperative day 15, the patient was discharged with overall good hemodynamics and recovery.

Fig. 1
figure 1

Computed tomography of abdomen showing large irregular saccular pseudoaneurysm arising from superior mesenteric artery

Full size image
Fig. 2
figure 2

Computed tomography of abdomen showing another 15 × 13 mm small psuedoaneurysm arising from jejunal branch of SMA. SMA, superior mesenteric artery

Full size image
Fig. 3
figure 3

Serial computed tomography of abdomen showing multiple fluid filled dilated jejunal and ileal loops and ascending colon with absent wall enhancement

Full size image
Fig. 4
figure 4

Histopathology report of excised gangrenous bowel showing extensive mucosal necrosis, transmural inflammation and haemorrhage and thrombosed blood vessels (A and B hematoxylin and eosin stain, original magnification 4×; C and D hematoxylin and eosin stain, original magnification 10×)

Full size image

Discussion

Visceral artery aneurysm (VAA) is a rare condition, accounting for only 5% of all intraabdominal aneurysms [4]. VAA comprises true aneurysm and pseudo aneurysm, depending on vessel wall involvement. The superior mesenteric artery aneurysm (SMAA) accounts for 3.5–8% of all VAA, whereas the development of pseudoaneurysm is exceedingly uncommon, with an incidence of 0.01–2.6% of all visceral artery pseudoaneurysm (VAPA) [5, 6].

The aetiology of SMA aneurysm and pseudoaneurysm includes various factors, including infection, inflammatory conditions (especially acute pancreatitis), atherosclerosis, collagen vascular disorders, inflammatory disorders, and infrequently, trauma and iatrogenic injury [5]. Based on existing research, it has been observed that a majority of these aneurysms are of mycotic origin, accounting for around 60% of cases, and are commonly associated with sub-acute bacterial endocarditis. Over the years, the development and usage of broad-spectrum antibiotics have led to a reduction in the occurrence of mycotic aneurysms. However, it is pertinent to note that this condition can still develop in patients who are receiving therapy or have already received it [7]. Patients with SMAA may present in various ways from rupture of the artery and causing sudden haemoperitoneum in 30–50% of cases to acute mesenteric ischemia leading to mortality of (67–100%) [8].

Polyarteritis nodosa (PAN) is rare, systemic, necrotizing vasculitis that involves medium-sized arteries. Gastrointestinal complications are prevalent and occur in up to 50% of patients suffering from PAN [9]. The multiple aneurysm formation is most common and involves medium size arteries like a hepatic artery, superior and inferior mesenteric arteries, renal arteries, and gastric artery [10]. Catastrophic bleeding can occur from the rupture of aneurysms, and prompt surgical and catheter-based intervention is required to control the source of bleeding.

Intra-abdominal complications are well mentioned following cardiac surgery. The incidence ranges from 0.5 to 2.6%. The most common being gastrointestinal bleeding followed by bowel ischemia [11]. The development of acute pancreatitis following cardiac surgery can vary depending on diagnostic criteria, and the incidence is estimated between 0.05 and 19% [12]. These complications can be attributed to risk factors like prolonged bypass time, valvular heart surgeries, perioperative hypo-perfusion, low cardiac output state, use of vasopressors, use of an intra-aortic balloon pump, and old age(> 70) [3]. Recognition at the earliest and prompt treatment is the key factor in helping the patients. Diagnosis is best established by computed tomography angiography (CTA).

Various interventions are being used for the treatment of visceral artery aneurysms and pseudoaneurysms, depending on the location of the artery and subsequent organ involvement. Catheter-based techniques are the primary modality of treatment for patients with significant comorbidities and favourable aneurysmal anatomy [13]. Open surgical repair of an artery is a preferred option for ruptured aneurysms with hemoperitoneum and bowel ischemia. The acute mesenteric ischemia due to spontaneous SMA pseudoaneurysm following cardiac surgery was scarcely reported earlier. In our case report, the probable reason is the release of pancreatic autoenzymes in the perivascular space and injury to the arterial wall, resulting in pseudoaneurysm formation [8]. This is a rare case of superior mesenteric artery pseudoaneurysm resulting in acute mesenteric ischemia following cardiac surgery.

Conclusion

Visceral artery aneurysms and pseudoaneurysms are rare complications following cardiac surgery. This case report describes the development of such complication following cardiac surgery.VAPA are more prone to rupture and catastrophic bleeding can occur. In cases where there is suspicion of intestinal ischemia or subacute bowel obstruction, it is imperative to quickly establish a diagnosis and proceed with surgical exploration.