Tetralogy of Fallot

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Chapter 77 Tetralogy of Fallot

LABORATORY AND DIAGNOSTIC TESTS

MEDICAL AND SURGICAL MANAGEMENT

Several medications may be used to medically manage TOF. The specific medication or combination of medications used depends on the child’s phsyiology. Propranolol (Inderal) is a beta-blocker that may be used to prevent or treat hypercyanotic spells and to treat arrhythmias. Diuretics, such as furosemide, may be used to promote diuresis. Though most children with TOF do not develop CHF because the pulmonic stenosis limits pulmonary blood flow, diuretics may be particularly useful in children with large ventricular septal defects and minimal pulmonic stenosis. In these same children, digitalis may be prescribed to improve cardiac performance by improving contractility and decreasing venous pressures. Further, digitalis slows conduction through the atrioventricular node and can therefore be used to treat selected cardiac arrhythmias (rarely given before correction unless shunt is too large).

Hypercyanotic spells are a medical emergency. A child experiencing a hypercyanotic spell should be placed in a knee-chest position and be given 100% oxygen by face mask. The knee-chest position improves venous return to the heart and therefore improves pulmonary blood flow. Oxygen is a potent pulmonary vasodilator and will also improve pulmonary blood flow. There are several medications that may also be helpful. Morphine is a sedative that decreases irritability, suppresses the respiratory center, and abolishes hyperpnea. Children with hypercyanotic spells quickly become acidotic. Therefore sodium bicarbonate, a potent systemic alkalizer, may be used to treat acidosis.

Palliative Surgical Procedures

Owing to the preference for earlier complete repair, the need for palliative procedures is diminishing. Historically, a Blalock-Taussig (BT) shunt was placed to increase the pulmonary blood flow until complete repair could be performed. A classic BT shunt is created when the subclavian artery opposite the side of the aortic arch is ligated, divided, and anastomosed to the contralateral pulmonary artery. The advantages of this shunt procedure are the ability to construct very small shunts that grow with the child and the ease of shunt removal during definitive repair. Collateral circulation will develop to ensure adequate arterial flow to the arm, although a blood pressure reading will not be obtainable in that arm.

More commonly used is the modified Blalock-Taussig shunt, which is essentially the same but uses a prosthetic material to connect the pulmonary artery to the subclavian artery. With the modified BT shunt, the size can be better controlled, which is critical in preventing CHF while providing adequate pulmonary blood flow. The modified BT shunt allows for placement despite aortic arch anomalies; however, a right-sided shunt is most often performed to ensure ease of removal at the time of complete repair. The removal of either the classic or the modified BT shunt is generally uncomplicated.

Both the classic and the modified BT shunts increase pulmonary blood flow by providing a means for systemic blood to enter the pulmonary circulation through the subclavian artery. This increases pulmonary blood flow under low pressure and avoids pulmonary congestion. This stabilizes pulmonary blood flow and improves cardiac and respiratory status until conditions are more favorable for complete repair.

NURSING INTERVENTIONS

Maintenance Care

1. Monitor for changes in cardiopulmonary status as described in the Nursing Assessment section in this chapter.

2. Monitor and maintain hydration status.

3. Monitor child’s response to medications (see the Medical Management section in this chapter).

4. Provide foods high in iron (to prevent iron deficiency anemia) and protein (to promote healing).

5. Protect child from potentially infectious contacts and promote preventive practices (to prevent subacute bacterial endocarditis).

6. Monitor for signs of complications and child’s response to treatment regimen.

7. Monitor growth and development to ensure timely achievement of developmental milestones.

Postoperative Care

TOF corrective surgery—monitor child’s clinical status for postoperative complications.

1. Monitor child’s cardiac function frequently per institutional policy.

2. Arrhythmias

3. CHF or ventricular dysfunction (more likely if ventricular incision is required)

4. Hemorrhage

5. Low cardiac output as evidenced by irritability, fatigue, poor feeding, change in neurologic responsiveness, tachycardia, auscultation of a gallop, diaphoresis, oliguria, pallor, peripheral cyanosis, and decreased capillary refill

6. Neurologic complications (refer to section in this chapter on Complications)

7. Pulmonary insufficiency as evidenced by rales, wheezing, increased respiratory effort, use of accessory muscles for respiratory effort, and cyanosis

8. Residual ventricular septal defect as evidenced by ongoing failure and echographic findings

9. Monitor child’s response to medications.

10. Monitor and maintain child’s fluid and electrolyte balance.

11. Monitor and maintain child’s respiratory status.

12. Monitor for chylothorax as evidenced by persistent pleural effusions.

13. Provide for child’s and family’s emotional needs (see the Supportive Care section in Appendix F).

14. Monitor and alleviate child’s pain (see Appendix I).

15. Provide developmentally appropriate stimulation and/or activities (see Appendix B).