Saved by the Collaterals: A Case of Chronic Mesenteric Ischemia

Abstract

A 59-year-old male with a history of peripheral vascular disease came to the hospital with worsening, dull but diffuse abdominal pain for one month. The pain was worsened after eating and associated with episodes of loose, non-bloody bowel movements. He had a decreased appetite and steadily lost about 20lbs of weight over the past few months. On initial presentation, he was frail and ill appearing with hypothermia of 36°C, tachypnea of 24bpm and tachycardia around 120bpm. He was otherwise awake with stable blood pressures. His abdomen was diffusely tender on palpation but soft with normal bowel sounds and no guarding, rebound or rigidity. He was found to have leukocytosis of 21x103/uL and a lactate of 15.9mmol/L. He had an elevated anion gap metabolic acidosis with a gap of 44, bicarbonate of 5mmol/L, pCO2 of 15mmHg and pH 7.11. He was immediately started on aggressive fluid resuscitation in an effort to clear his lactic acidosis. A CTA of the abdomen revealed a celiac artery occlusion, proximal SMA occlusion and occlusion of the IMA by his aorto-bifemoral bypass graft. It was diagnostic of mesenteric ischemia. Fortunately, he had collateral circulation supplying his liver and colon, which protected him from complete necrosis of the bowel and ischemic liver disease. The left gastric artery and iliac collaterals to the distal colon provided much of the circulation. He underwent angiography and stenting of his SMA. There was atherosclerotic disease with an acute thrombus overlapping. He improved after the surgery and fluid stabilization with his lactate declining to 1.3mmol/L, acidemia, anion gap and white blood cell count improving back to normal range. He was anticoagulated with heparin to warfarin bridging and then later discharged to a short-term rehab facility. Chronic mesenteric ischemia is episodic or constant hypo-perfusion of the intestines usually caused by stenosis or occlusion. Atherosclerosis of the mesenteric vessels is fairly common in the general population. 18 percent of the population above 65 is eventually found to have significant stenosis. Clinical manifestations are usually rare due to the development of a large collateral circulation network over time. Patients usually present with dull, cramping, post-prandial pain with gradual weight loss. An acute thrombosis can set off acute mesenteric ischemia requiring prompt revascularization usually with angiography and stenting. Close follow-up is needed, as restenosis is common.