Coarctation of the Aorta

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Chapter 15 Coarctation of the Aorta

PATHOPHYSIOLOGY

Coarctation of the aorta is a localized narrowing or obstruction of the aortic lumen. The narrowing usually occurs adjacent to the site of insertion of the ductus arteriosus. Narrowing increases pressure in the ascending aorta, which results in higher pressure to the coronary arteries and vessels that arise from the aortic arch. Pressure is decreased distal to the site of obstruction. Coarctation of the aorta is often associated with bicuspid aortic valve. Other associated defects include other forms of left-sided obstruction, patent ductus arteriosus, and ventricular septal defect. Prognosis is excellent with surgical intervention.

INCIDENCE

1. Accounts for 8% to 10% of individuals with congenital cardiac defects

2. Male-female ratio is 2:1

3. More common in families of European descent

4. Known familial clustering of left ventricular outflow tract obstructions, including coarctation of the aorta

5. Occurs in 30% of patients with Turner’s syndrome

CLINICAL MANIFESTATIONS

1. Absent or diminished femoral pulses

2. Cool lower extremities with prolonged capillary refill time

3. Blood pressure differential between upper and lower extremities

4. May have systolic or diastolic murmurs

5. May have an ejection click

6. Two patterns of presentation:

a. Neonatal—asymptomatic until ductus arteriosus closes or until onset of left ventricular failure. Present with severe congestive heart failure that can progress to shock if untreated
b. Postneonatal—typically, asymptomatic and present with hypertension. Other symptoms are sequelae of coarctation of the aorta and include calf pain, headache, epistaxis, dizziness, and fainting

COMPLICATIONS

1. Cardiovascular: hypertension, recurrent coarctation of the aorta, aortic aneurysm, cerebrovascular accident

2. Infectious disease: bacterial endocarditis

LABORATORY AND DIAGNOSTIC TESTS

1. Electrocardiogram (ECG)—normal or may reveal left ventricular hypertrophy or right bundle branch block.

2. Chest radiograph—neonates with severe coarctation of the aorta may have cardiomegaly and pulmonary edema; infants and older children may have normal or slightly enlarged heart with visible dilation of the ascending aorta. Rib notching may be present in older children.

3. Echocardiogram—reveals site and extent of coarctation, presence of other abnormalities, left ventricular dysfunction.

4. Cardiac catheterization—required to evaluate other defects or if echocardiography provides insufficient information.

5. Magnetic resonance imaging—most useful in older children and adults to assess for recurrent coarctation.

6. Preoperative laboratory data—refer to Appendix D for normal values and ranges of laboratory and diagnostic tests.

a. Complete blood count—used to screen hematologic status preoperatively, including evaluation of baseline white blood cell count, hemoglobin, and hematocrit.
b. Baseline electrolyte levels and renal function panels—to assess renal function and metabolic status preoperatively: sodium, potassium, chloride, carbon dioxide, blood urea nitrogen, and creatinine.
c. Blood coagulation studies—prothrombin time, partial thromboplastin time, platelet count.
d. Type and cross-match—in the event that transfusion is required.

MEDICAL AND SURGICAL MANAGEMENT

Management strategies vary by age of child and severity of the coarctation of the aorta. Neonates with critical coarctation of the aorta require intravenous infusion of prostaglandin E1 to reopen the ductus arteriosus. They may also require stabilization with inotropic agents and respiratory support, and are scheduled for repair when medically stable. Traditionally, defects in children with hypertension who were otherwise asymptomatic were repaired between the age of 3 and 5 years. At present, many centers schedule for repair at presentation to decrease the risk of residual hypertension and postoperative complications.

Repair refers to using one of several methods including resection with end-to-end anastomosis, subclavian flap aortoplasty (ligation and use of the subclavian artery to enlarge the aorta), patch aortoplasty, or conduit insertion. The team selects the method of repair most appropriate for the child’s age and anatomy. The overall mortality rate for repair of isolated coarctation of the aorta is less than 5% and in older children is less than 1%. Balloon dilation is an effective treatment for recurrent coarctation of the aorta and is being used in some institutions to treat native coarctation of the aorta. Finally, stents may be placed in the aorta for mild native or recurrent coarctation of the aorta in older children and adults.

Postoperative Complications

1. Cardiovascular

a. Hypertension is the most common postoperative problem and is more common in older children
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