TETRALOGY OF FALLOT (TOF)

Mary Beth Sanders BSN & Laura Durbin BSN

East Carolina University

College of Nursing, Greenville, North Carolina

Incidence and Risk• occurs in 3 of every 10,000 live births. • most common cause of cyanotic cardiac

disease in patients beyond the neonatal age• accounts for up to one-tenth of all

congenital cardiac lesions• There are a number of state-based

programs monitoring CHDs among newborns and young children, but currently no population-based tracking system exists to look at this growing population of older children and adults with heart defects.

• It is the least diagnosed CHD during the prenatal period.

• Factors that increase the risk for this condition during pregnancy include:• Alcoholism in the mother• Diabetes• Mother who is over 40 years old• Poor nutrition during pregnancy• Rubella or other viral illnesses during

pregnancy• Maternal intake of retinoic acid in 1st trimester

• Associated conditions• trisomies 21, 18, 13• microdeletions of chromosome 22

• DiGeorge Syndrome.

• 3% risk of recurrence in a family

Surgical Treatment of TOF

Primary Repair• VSD is closed• widening of the pulmonary valve or artery to increase

pulmonary blood flow.• Pulmonary regurgitation is a complication patching to

pulmonary artery.• Severe cases may need pulmonary valve replacement• Ventricular arrhythmia is the most common long term

complication of repair

Blalock-Taussig procedure (temporary procedure)• surgical construction of a shunt between the right subclavian

artery and the right pulmonary artery as a temporary measure to increase pulmonary blood flow to the lungs.

• Can be used as a palliative procedure to establish pulmonary blood flow prior to primary repair.

Prostaglandin E (PGE)

• Stabilizes infants with severe cyanosis by reopening or maintaining the ductus arteriosus • In most infants, the ductus will reopen within 30

minutes to 2 hours after starting PGE1

• Administered as a continuous IV infusion at 0.05-0.2 ug/kg/min.

• Side effects include• Refractory hypotension from vasodilation• Apnea• Hyperthermia/ Flushing• Seizures

• Pharmacology• Prostaglandins are long chain

unsaturated fatty acids produced by the action of the enzyme clooxygenase and are classified into groups E,D,A, F & B• PGE is also produced in the kidney in response

to decreased renal blood flow prevents vasoconstriction and renal ischemia

• PGE vasodilates all arterioles, inhibits platelet aggregation, and stimulates uterine and intestinal smooth muscles.

Physiology of TOF

Four Different Defects In TOF• large ventral septal defect: An opening between the 2 bottom

chambers of the heart.• Pulmonary valve stenosis or atresia: Pulmonary blood flow

obstruction. This is due to a narrowing at the pulmonary valve or the pulmonary arteries. • Right ventricular hypertrophy: Caused by the heart working harder to

pump blood through the body because of the narrow pulmonary valve.

Overriding aorta: The aorta overrides the ventral septal defect.

Tetralogy of Fallot

Pink TOF• Mild outflow tract obstruction

• Blood is shunted from left to right.• Blood is able to enter the pulmonary

system thus, it is oxygenated. • Infant is “pink”.• Infants and children can experience

TET spells.• Surgical repair is between 18 months

and 3 years old.

Blue TOF• Severe outflow tract obstruction

is present.• Blood is shunted from right to left.• Pulmonary blood flow is

dependent upon R to L shunting through the PDA.• Infant will require PGE until

surgical repair is undertaken.

Radiographic Findings in TOF

• Classic boot-shaped heart• This finding is a result of

the upward lifting of the apex of the heart.

• This is due to the hypertrophy of the right ventricle.

• The more pronounced the upward lifting, the greater the outflow obstruction is.

Blood Flow in Infants with Tetralogy of Fallot• Narrowing of the right

ventricular outflow tract at the pulmonary artery.

• Deoxygenated blood is prevented from entering pulmonary system.

• Right ventricle hypertrophies attempting to push blood through stenosis.

• VSD allows shunting left to right in mild stenosis “ pink” TET

Blood flow in infants with Tetralogy of Fallot• Cyanosis occurs when the right

tract outflow obstruction impedes the blood flow significantly.

• Blood in the right ventricle takes the path of least resistance into the left ventricle.

• This creates a right-to-left shunt

• Blood is directed away from the pulmonary system

• Blood leaves heart before being oxygenated.

• Thus, the infant is cyanotic.

References

• Bailliard, F., & Anderson, R. H. (2009, January 13). Tetralogy of Fallot. Orpanet journal of rare diseases, 4. http://dx.doi.org/10.1186/1750-1172-4-2

• Buck, M. L. (2000). Alprostadil (pge1) for maintaining ductal patency. Pediatric Pharmacotherapy, 6. Retrieved from http://www.medscape.com/viewarticle/410907_2

• Ferguson, E. C., Krishnamurthy, R., & Oldham, S. A. (2007). Classic imaging signs of congenital cardiovascular abnormalities. RadioGraphics, 27, 1323-1334.

http://dx.doi.org/10.1148/rg.275065148• Ismail, S. R., Kabbani, M. S., Najm, H. K., Abusuliman, R. M., & Elbarbary, M. (2010,

April ). Early outcome of tetralogy of fallot repair in the current era of management. J Saudi Heart Association, 22(2), 55-59. http://dx.doi.org/10.1016/j.jsha.2010.02.006

• Quek, S. C., & Lee, C. N. (2010). The modified blalock-taussig shunt revisited. Cardiology in the Young, 20, 208-209. http://dx.doi.org/10.1017/S1047951109991041

References

• Martínez, J., Gómez, O., Bennasar, M., Olivella, A., Crispi, F., Puerto, B., & Gratacós, E. (2010). The 'question mark' sign as a new ultrasound marker of tetralogy of Fallot in the fetus. Ultrasound In Obstetrics & Gynecology, 36(5), 556-560. doi:10.1002/uog.7614• Westmoreland, D. (1999). Critical congenital cardiac defects in the

newborn. Journal Of Perinatal & Neonatal Nursing, 12(4), 67-87.

References

• Scholz, T. D., & Reinking, B. E. (2012). Congenital heart disease. In Avery’s diseases of the newborn (9th ed., pp. 762-768). Phildelphia, PA: Elsevier• U.S. National Library of Medicine website. (2011).

http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0002534/• Westmoreland, D. (1999). Critical congenital cardiac defects in the

newborn. Journal Of Perinatal & Neonatal Nursing, 12(4), 67-87.