Review Question - QID 214334

This patient has bilateral lower extremity claudication (numbness, tingling, and pain due to decreased blood flow), hypertension, a systolic murmur, and decreased dorsalis pedis pulses, which are consistent with coarctation of the aorta. Patients with coarctation of the aorta can have rib notching due to increased collateral blood flow through the intercostal arteries.

Coarctation of the aorta is an acyanotic congenital heart defect marked by narrowing of the aorta at the aortic isthmus. The decreased aortic cross-sectional area causes increased blood flow proximal and decreased blood flow distal to the obstruction. To compensate for the decreased blood flow distal to the obstruction, collateral circulation forms between the pre- and post-coarctation systems. Most commonly, blood travels from the subclavian artery -> internal mammary arteries -> intercostal arteries -> post-coarctation descending thoracic aorta. The increased perfusion through the intercostal arteries causes pressure atrophy and resorption of the neighboring ribs, which may be visible on chest radiograph as inferior rib notching. Rib notching is a result of chronic disease and is often seen in children > 5 years of age and young adults.

Incorrect Answers:
Answer 1: Anti-intrinsic factor autoantibodies are associated with pernicious anemia, a condition of vitamin B12 deficiency. Vitamin B12 deficiency causes megaloblastic anemia and neurological symptoms such as paresthesias (not claudication), spasticity, ataxia, and neuropsychiatric disorders.

Answer 2: Hyaline arteriosclerosis is associated with essential hypertension, normal aging, and chronic diabetes. Hyaline arteriosclerosis is the cause of diabetic nephropathy, ophthalmopathy, and peripheral neuropathy in a stocking and glove distribution (not claudication).

Answer 4: Spinal cord arteriovenous malformation is a rare cause of bilateral lower extremity paresthesias and pain in young patients. The onset of paresthesias and pain is often acute (not gradual) due to rupture, and may be associated with neurological deficits depending on the extent of oxygen deprivation to the spinal cord.

Answer 5: Spinal nerve compression is associated with lumbar spinal stenosis, a common cause of neurogenic (not vascular) claudication. Impingement or inflammation of the nerves emanating from the spinal cord causes pain, numbness, and weakness of the bilateral lower extremities that are classically relieved by a change in position or flexion of the waist.

Bullet Summary:
Coarctation of the aorta causes retrograde blood flow through the intercostal arteries causing inferior rib notching on chest radiograph.