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6. Coarctation of the Aorta
Clinical Presentation: Preductal and severe postductal coarctation: presents shortly after birth with symptoms of heart failure. Preductal also causes differential cyanosis—the upper body is normal and the lower body is cyanotic. (The pressure after the constriction is low, causing deoxygenated blood to flow from the PA through the ductus arteriosus and into the aorta. RÆL shunt) Moderate coarctation: child presents with hypertension (usually postductal)
Elevated BP in upper body (Most common presentation)
Weak and delayed femoral pulses
If coarctation is distal to branching of left subclavian, then BP in arms > BP in legs (normal person has higher BP in legs). If coarctation is proximal to branching of the left subclavian, then BP in right arm > BP in left arm
Weak, systolic ejection murmur caused by flow through coarctation.
Continuous murmurs over chest from collateral circulation
Diagnostic Imaging and Testing:
Chest x-ray: notching of inferior surface of ribs, indented aorta at coarct.
ECG: LVH due to pressure load
Echo: visualize coarctation, determines pressure across coarctation
MRI: length and severity of coarctation
Treatment: Severe obstruction in neonates: prostaglandin infusion to keep ductus arteriosus open and maintain blood flow to descending aorta until surgery. Surgical repair for kids: excise coarctation and put in a synthetic patch. For older kids and adults (or people with recurrent coarctation), use a transcatheter balloon to dilate, may/ may not use stent. Antibiotic prophylaxis for endocarditis
Etiology: Discrete narrowing of aortic lumen, 2 types:
Preductal (2%): narrowing occurs proximal to the ductus arteriosus, results from intracardiac anomaly during fetal life, causing decreased blood flow through left side of heart and hypoplastic development of the aorta
Postductal (98%): narrowing occurs distal to the ductus arteriosus, caused by ductal tissue extending into the aorta. When the ductus constricts after birth, ductal tissue in aorta constricts too, obstructing the aorta.
Pathology: LVH Pathophysiology: coarctation causes increase in LV pressure, decreased blood flow to descending aorta and lower extremities (head and upper extremities rarely affected.) LV pressure load Æ LVH and dilation of collateral (intercostals) blood vessels (latter causes erosion of lower ribs = rib notching) Epidemiology: 1/6000, associated with Turner’s syndrome (45, XO)