14

CASE 14


A 49-year-old man presented to his physician complaining of lower back pain. The pain has lasted for 3 days and is unaffected by movement, though the pain is alleviated somewhat when the patient’s thighs are flexed. When the anterior abdominal wall was palpated, a tender pulsatile mass was detected just superior to the umbilicus. The physician also detected diminished pulses in the femoral and dorsalis pedis arteries, and bruits were heard over the palpable mass. Imaging studies showed an abdominal aortic aneurysm (Fig. 3-1) with atherosclerotic lesions of the common iliac arteries. The aneurysm was surgically repaired by the insertion of a synthetic prosthesis.


image

FIGURE 3-1 CT images of an infrarenal abdominal aortic aneurysm. Upper right, lateral view. Upper left, anterior view with intravenous contrast infusion. Lower left, anterior view. Lower right, posterior view.


(Towsend C et al.: Sabiston Textbook of Surgery, 17e. WB Saunders, 2004. Fig. 64-4.)



ANATOMICALLY, WHERE DO AORTIC ANEURYSMS COMMONLY OCCUR?


Most aortic aneurysms occur below the level of the renal arteries (Figs. 3-1 and 3-2). Less frequently the aneurysm involves the suprarenal abdominal aorta and thoracic aorta.


image

FIGURE 3-2 Human aorta showing an infrarenal abdominal aortic aneurysm at the arrow.


(Towsend C et al.: Sabiston Textbook of Surgery, 17e. WB Saunders, 2004. Fig. 64-2.)


Patients with abdominal aneurysms frequently have involvement of the common iliac and internal iliac (hypogastric) arteries. Rarely are the external iliac arteries involved.



WHERE DO ABDOMINAL AORTIC ANEURYSMS MOST COMMONLY RUPTURE?


The abdominal aorta runs retroperitoneally in the abdomen. Consequently, abdominal aortic aneurysms most commonly rupture into the retroperitoneal space. Although rupture is a life-threatening condition, bleeding into the retroperitoneum may contain the rupture. Specifically, 80% rupture into the left retroperitoneal space. Most of the other 20% rupture into the peritoneal cavity. The rupture in this case is not contained, and massive bleeding leads to a rapid deterioration in circulatory function.



AT WHAT VERTEBRAL LEVELS DOES THE ABDOMINAL AORTA BEGIN AND END?


The abdominal aorta is a continuation of the thoracic aorta. The thoracic aorta passes through the aortic hiatus of the diaphragm at the level of the tenth thoracic vertebra. The abdominal aorta continues its inferior course until it bifurcates into the common iliac arteries at the level of the fourth lumbar vertebra.



WHAT ARE THE BRANCHES OF THE ABDOMINAL AORTA?

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Jun 16, 2016 | Posted by in ANATOMY | Comments Off on 14

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