Case Files Surgery, (LANGE Case Files) 4th Ed.

SECTION II. Clinical Cases

CASE 37

A 66-year-old woman is seen in the outpatient clinic for an evaluation of weight loss. The patient says that 6 months ago her weight was 155 lb (70.5 kg) but over the past several months has steadily declined to 105 lb (47.7 kg). The patient attributes her weight loss to an inability to eat. She indicates that whenever she tries to eat a meal, she develops intense abdominal pain that is severe and diffuse throughout the entire abdomen. To avoid this pain, the patient has limited herself to small meals and soups. She denies any fever, malaise, nausea, vomiting, or constipation. Her past medical history is significant for hypertension for which she takes an angiotensin-converting enzyme inhibitor. She smokes approximately one pack of cigarettes per day and consumes two glasses of wine per day. The physical examination reveals a thin woman in no distress. Her skin and sclera are nonicteric, and bilateral carotid bruits are present. The results of her cardiopulmonary examination are unremarkable. The abdomen is scaphoid, nontender, and without masses. Her stool is Hemoccult negative. Her femoral pulses are diminished, with audible bruits bilaterally. The pulses are diminished in both lower extremities. Laboratory evaluations are obtained revealing a normal complete blood count and normal electrolyte levels. The serum urea nitrogen, creatine, and glucose values are within the normal range, as are the results from a urinalysis. The 12-lead electrocardiogram reveals a normal sinus rhythm.

Images What is the most likely diagnosis?

Images What is the most likely mechanism causing the problem?

Images What is the best treatment?

ANSWERS TO CASE 37: Mesenteric Ischemia

Summary: A 66-year-old woman with carotid and femoral artery bruits presents with signs and symptoms consistent with mesenteric angina leading to “food fear” and massive unintentional weight loss.

• Most likely diagnosis: Postprandial abdominal pain, massive weight loss, and signs of advanced atherosclerotic changes suggest possible chronic mesenteric ischemia.

• Most likely mechanism causing the problem: Occlusion of the mesenteric arteries related to atherosclerotic changes.

• Best treatment: Aortomesenteric bypass grafting.

ANALYSIS

Objectives

1. Learn the causes, presentations, diagnosis, and treatment of mesenteric ischemia.

2. Learn the diagnosis and treatment of patients with mesenteric angina related to mesenteric occlusion.

Considerations

The patient presents with the classic symptom complex of food fear with postprandial pain and significant weight loss, which are the hallmarks of chronic mesenteric ischemia. However, a thorough workup for other conditions causing abdominal pain is important because mesenteric revascularization is a procedure associated with some morbidity. When more common causes of upper and lower intestinal sources of abdominal pain are ruled out (either by strong clinical impression, endoscopy, or imaging studies), the mesenteric arteries can be studied. At centers with high-quality vascular laboratories, duplex ultrasonography is an excellent screening test. In this setting, a normal study performed both before and after a food challenge can accurately rule out proximal mesenteric artery vascular disease. Magnetic resonance angiography (MRA) and computed tomographic angiography (CTA) can give an accurate assessment of the superior mesenteric and celiac artery origins. Selective arteriography with lateral aortic projections remains the gold standard for definitive diagnosis and therapy planning. The best treatment for chronic mesenteric ischemia is operative revascularization.

APPROACH TO: Mesenteric Ischemia

CLINICAL APPROACH

Chronic Mesenteric Ischemia

The most common cause of chronic mesenteric ischemia is atherosclerotic occlusive disease of the mesenteric arteries. Typically, a patient has occlusion of two of the three major mesenteric vessels (Table 37–1), with significant disease in the remaining vessel. In mesenteric ischemia without atherosclerotic disease, arteriography can be useful in guiding the therapy. Rarely, patients develop celiac artery compression causing an ischemic syndrome.

Table 37–1 • VISCERAL BLOOD SUPPLY

Images

Open revascularization procedures with antegrade aortomesenteric bypass and perivisceral aortic endarterectomy are the best treatment options for maintenance of long-term arterial patency. In the face of higher operative risks or complicating aortic atherosclerosis, a retrograde bypass from an alternative arterial source (such as the iliac artery) has a role. Advanced age, the presence of typical cardiovascular comorbidities, and severe nutritional depletion are factors contributing to the increase in morbidity and mortality associated with open mesenteric reconstructions. Given the high-risk profile of patients with chronic mesenteric ischemia, endovascular reconstruction is being increasingly applied by many groups; the results reported have demonstrated reduced complication rates in comparison to open revascularization and 2-year primary patency rates of 70% to 95%.

Acute Mesenteric Ischemia

Acute mesenteric ischemia is a surgical emergency. It can be caused by an acute embolus in the superior mesenteric artery (SMA) or the celiac artery, with the heart being the source of the embolus (Figure 37–1). Embolism involving the celiac artery is exceedingly rare. These patients generally do not report history of chronic symptoms prior to the acute event. Arteriography can aid in the diagnosis but may lead to treatment delays and should not be applied toward individuals who are suspected of having intestinal ischemic necroses. Clinical judgment should be exercised in deciding whether imaging should be performed prior to emergent laparotomy. On laparotomy, the bowel can range in appearance from frankly necrotic (a late presentation) to dusky and nonmotile. With an embolus, the proximal jejunum is spared because of small proximal collaterals. The embolus tends to lodge in the more distal main SMA trunk. Embolectomy may be all that is required, and with ischemia, resection of the involved bowel segment is often required. A second-look laparotomy should be strongly considered if the remaining bowel does not appear perfectly viable. In selective cases of acute SMA embolism without clinical evidence of bowel ischemia, a trial of catheter-directed thrombolytic therapy may be attempted; however, the surgeon should be prepared to proceed with prompt abdominal exploration if worsening abdominal symptoms develop or clot lysis fails to occur.

Images

Figure 37–1. Origins of the visceral arteries arising from the abdominal aorta.

Less Common Causes of Mesenteric Ischemia

Nonocclusive mesenteric ischemia due to low-flow states can develop in a setting of critical illness or as a result of vasoconstrictive medications administration. Mesenteric venous thrombosis is uncommon and can occur as the result of advanced infectious processes related to gastrointestinal tract pathologies, such as appendicitis and diverticulitis. Also, mesenteric venous thrombosis may occur as a manifestation of a hypercoagulable state. Chronic mesenteric ischemia symptoms can occur as the result of external compression of the celiac artery by the diaphragm, which is referred to as the celiac artery compression syndrome or median arcuate ligament syndrome.

COMPREHENSION QUESTIONS

37.1 A 66-year-old man is admitted to the coronary care unit because of new-onset atrial fibrillation. After 24 hours, he develops the acute onset of abdominal pain and distension, and on examination he is found to have diffuse peritonitis. The patient undergoes exploratory laparotomy with resection of necrotic bowel. Which of the following is the most important postoperative treatment for this patient?

A. Intra-arterial thrombolytic therapy with streptokinase

B. Cardioversion

C. Systemic heparinization

D. Early oral feeding to stimulate intestinal lengthening

E. Revascularization of the SMA and celiac arteries

37.2 Which of the following clinical presentations is the most typical of mesenteric angina?

A. Diarrhea that occurs following fatty meals, steatorrhea, and chronic epigastric and back pain

B. Daily postprandial abdominal pain, associated with a 40-lb weight loss

C. Recurrent, intermittent epigastric abdominal pain that occurs approximately 1 hour after meals

D. Chronic, persistent abdominal and back pain of 1-month duration and a 10-lb weight loss

E. Recurrent intermittent postprandial abdominal pain

37.3 In which segment of the intestine is ligation of the inferior mesenteric artery during aortic aneurysm repair most likely to produce ischemia?

A. Transverse colon

B. Low rectum

C. Splenic flexure colon

D. Right colon

E. Distal small bowel

37.4. A 69-year-old woman with cardiogenic shock following an anterior wall myocardial infarction develops diffuse abdominal pain. On physical examination she is noted to have BP 85/50 mm Hg, pulse 90 beats/min, nontender abdomen, and cool extremities, with skin mottling in the lower extremities. Which of the following is the best management approach at this time?

A. Exploratory laparotomy

B. Dobutamine drip

C. Mesenteric angiography

D. Heparin drip

E. Mesenteric revascularization

ANSWERS

37.1 C. This patient likely has a mural thrombus of the left atrium, which has embolized to the SMA, leading to bowel necrosis. Initiation of intravenous heparin is important to stabilize and prevent further extension of the clot. Other important steps include antibiotic therapy to prevent sepsis, echocardiography to assess for an intracardiac thrombus, and possibly a second-look laparotomy to evaluate the viability of the remaining bowel. Thrombolytic therapy is indicated in patients with SMA embolism with ischemic pain and no clear evidence of bowel necrosis, therefore is not indicated in this patient. Mesenteric arterial reconstruction is not needed in patients with SMA embolism, because the arterial occlusion is an acute secondary process rather than a primary occlusive process such as in chronic mesenteric ischemia.

37.2 B. Mesenteric angina produces symptoms after an increase in GI tract workload such as after meals, and the weight loss develops because the patient learns to avoid this challenge. Choice A is more consistent with chronic pancreatitis with pancreatic exocrine insufficiency. Choice C is more typical of biliary tract disease, and D correlates with pancreatic malignancy. Choice E could be produced by a variety of GI obstructive processes.

37.3 C. Splenic flexure colon. The SMA supplies the bowel from distal duodenum to the midtransverse colon. The IMA supplies the descending colon down to the upper rectum. The lower rectum receives blood supply from the hemorrhoidal arteries that originate from the iliac artery. The “water-shed” areas (areas between defined blood supplies that rely on blood flow from collateral circulations) of the GI tract include the splenic flexure of colon and distal sigmoid colon/upper rectum.

37.4 B. Dobutamine drip. The patient described appears to have a systemic low-flow state related to poor left ventricular output, resulting in inadequate mesenteric and lower extremity blood flow. The patient’s physical examination does not suggest frank necrosis of the bowel at this point; therefore exploratory laparotomy is not indicated. In fact, given the patient’s current cardiac condition, unnecessary exploration of the abdomen could be a fatal insult. Because the current problem is caused by “pump failure” rather than mechanical obstruction of the arteries, treatment should be directed toward improving cardiac functions.

CLINICAL PEARLS

Images A patient with chronic mesenteric ischemia almost always has significant unexplained weight loss. If there is no weight loss, the diagnosis should be questioned.

Images An abdominal bruit is a very nonspecific finding. It does not pay to be dogmatic about its presence or absence.

Images Acute mesenteric ischemia is a surgical emergency.

Images Exposure of the SMA for embolectomy is accomplished via the root of the small bowel mesentery.

REFERENCES

Lin PH, Kougias P, Bechara C, et al. In: Brunicardi FC, Andersen DK, Billiar TR, et al, eds. Schwartz’s Principles of Surgery. 9th ed. New York, NY: McGraw-Hill; 2010:701-775.

Melzer AJ, Melo N, Balcom IV JH. Acute mesenteric ischemia. In: Cameron JL, Cameron AM, eds. Current Surgical Therapy. 10th ed. Philadelphia, PA: Mosby Elsevier; 2011:853-854.

Wang GJ, Resnick AS. Management of chronic mesenteric ischemia. In: Cameron JL, Cameron AM, eds. Current Surgical Therapy. 10th ed. Philadelphia, PA: Mosby Elsevier; 2011:855-857.