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
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
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.
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
Antihypertensive Medications
1. Sodium nitroprusside (Nipride)—continuous infusion used to treat acute postoperative hypertension; acts on the smooth muscle to produce peripheral vasodilation, causing decreased arterial pressures
2. Propranolol (Inderal)—used to treat postoperative hypertension; acts as a beta-blocker of cardiac and bronchial adrenoreceptors, decreasing heart rate and myocardial irritability and potentiating contraction and conduction pathway
3. Captopril (Capoten)—used to treat postoperative hypertension; works on the renin-angiotensin system to reduce afterload
Nursing Interventions
Preoperative Care
2. Promote child’s understanding by use of age-appropriate terminology (see Appendix F).
3. Provide information to assist parents in understanding child’s condition.
4. Stress the importance of normal well-child care and immunizations.
5. Stress the importance of age-appropriate social and recreational activities (see Appendix D).
Postoperative Care
1. Monitor cardiac status frequently per institutional policy.
2. Control hypertension if present. Since pain or anxiety can increase blood pressure, ensure adequate treatment of pain and/or anxiety before starting antihypertensive medications.
3. Use no cuff pressure or arterial punctures in left arm if left subclavian flap was performed, because only collateral vessels are providing arterial circulation.
4. Promote optimal respiratory status.
5. Monitor for signs and symptoms of hemorrhage.
6. Monitor and correct hydration status.
7. Monitor child’s response to medications and blood products.
8. Resume oral feedings slowly; monitor tolerance and abdominal status.
9. Relieve postoperative pain and anxiety using medication, parental presence, and age-appropriate interventions (see Appendix I).
10. Provide age-appropriate diversional activities (see the relevant section in Appendix F).
11. Provide age-appropriate explanations before treatments and painful procedures (see the Preparation for Procedures and Surgery section in Appendix F).
12. Perform wound care according to instutitional policy.
13. Assess for signs and symptoms of infection.
Discharge Planning and Home Care
Review the following points with parents and caregivers before discharge:
1. Appropriate wound care according to institutional policy
2. Observe for signs and symptoms of infection
3. Activity limitations as instructed by the health care team
4. Appropriate lifting techniques for infants and toddlers: avoid grabbing child under the arms, support child’s head and shoulders with one arm and the lower body with the other
5. Pain management (refer to Appendix I)
6. Administration of medications and monitoring child’s response
7. Importance of follow-up to screen for hypertension, recurrent coarctation, and other complications
8. Good dental hygiene and antibiotic prophylaxis before and after invasive procedures to prevent bacterial endocarditis
9. Importance of routine well-child care and immunizations
10. Importance of developmentally appropriate social and recreational activities (refer to Appendix B)
11. Importance of maintaining expectations for behavior and discipline, and supporting the child’s complete recovery
CLIENT OUTCOMES
1. Child will be free of postoperative complications.
2. Child will have adequate pain management.
3. Child will demonstrate sense of mastery of the surgical experience as evidenced by expression of feelings and resumption of normal activity level.
4. Child will participate in physical activities appropriate for age.
5. Parent will verbalize home care and follow-up instructions.
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