Acute Abdominal Pain in a Patient With Atrial Fibrillation

Case Study

The bedside nurse initiated a rapid response event after the patient had an abrupt onset of severe abdominal pain while sitting calmly watching television. On prompt arrival of the rapid response team, the patient started to have severe nausea and vomiting. It was noted that the patient was a 70-year-old female with a known history of persistent atrial fibrillation, coronary artery disease with coronary stent placement a month before. She was admitted to the hospital for evaluation after a mechanical fall at home. Her apixaban was currently being held while the safety of restarting anticoagulation in the patient was being determined.

Vital Signs

Temperature: 98.2 °F, axillary
Blood Pressure: 130/85 mmHg
Pulse: 120 beats per min – irregular rhythm with rapid ventricular rate on telemetry
Respiratory Rate: 25 breaths per min
Pulse Oximetry: 97% on room air

Focused Physical Examination

A quick exam showed an elderly African American female in significant distress. Her abdominal exam showed a soft, non-tender, non-distended abdomen without peritoneal signs indicating pain out of proportion to the exam. A cardiovascular exam showed an irregular rhythm with no abnormal heart sounds. The pulmonary exam was benign.

Interventions

A cardiac monitor with pacer pads was attached. The patient was immediately given 2 mg intravenous (IV) morphine with some improvement in pain. 4 mg IV ondansetron was administered for nausea. A stat abdominal X-ray was unremarkable. Lab workup, including a complete blood count, comprehensive metabolic panel, lactic acid level, and lipase level, were sent. Fluid resuscitation was provided after the laboratory results showed increased hematocrit with concerns for hemoconcentration and metabolic derangements. Because of the pain out of proportion of abdominal exam and history of atrial fibrillation, there was a high suspicion of mesenteric ischemia; thus, a stat mesenteric angiography was ordered. Computed tomography (CT) angiography showed a complete lack of visualization of the superior mesenteric artery (SMA) origin. Stat general surgery consult was placed, the patient was started on therapeutic heparin infusion, and was transferred to the intensive care unit for further care.

Final Diagnosis

Acute mesenteric ischemic secondary to arterial embolism.

Acute Mesenteric Ischemia

The gastrointestinal (GI) tract has a rich blood supply which aids in the absorption of nutrients in the gut. The intestines derive a significant portion of their blood flow through direct branches of the aorta: celiac trunk, SMA, and inferior mesenteric artery ( Table 54.1 ). The venous circulation parallels the arterial circulation. The presence of significant collateral circulation between the branches of these three major vessels protects the gut from ischemia. This collateral blood flow allows the intestine to tolerate up to 12 h of reduced blood flow without significant damage. However, some “watershed” areas of the colon (splenic flexure and rectosigmoid junction) are not as richly supplied by collateral circulation and are more prone to develop ischemia in the setting of reduced blood flow.

Table 54.1

Blood supply of gastrointestinal tract

Artery	Supply
Celiac artery	Distal esophagus, stomach, liver, spleen, pancreas, proximal duodenum
Superior mesenteric artery	Duodenum, pancreas, small intestine, cecum, ascending colon, proximal two-third of the transverse colon
Inferior mesenteric artery	Distal one-third of transverse colon, descending colon, sigmoid colon, rectum

Definition and Diagnosis

Acute mesenteric ischemia (AMI) generally refers to ischemia of the small bowel in contrast to acute colonic ischemia (or ischemic colitis), which refers to ischemia of the large bowel. AMI is a life-threatening vascular emergency requiring early diagnosis and intervention to adequately restore mesenteric blood flow and prevent bowel necrosis and patient death.

AMI remains a diagnostic challenge for clinicians, and the delay in diagnosis contributes to the continued high mortality rate ( Table 54.2 for common differential diagnosis of AMI). Early diagnosis and prompt, effective treatment are essential to improve the clinical outcome. The classic presentation of AMI remains “pain out of proportion to the exam.” Involvement of proximal small bowel can also produce signs and symptoms such as nausea and vomiting. AMI has often been classified into four distinct types ( Table 54.3 ).

Table 54.2

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