History
In the current era, a large proportion of patients are diagnosed prenatally. Postnatally, the most common clinical presentation is an asymptomatic cardiac murmur. In early infancy, cyanosis may be mild or absent but tends to be progressive. Dyspnea upon exertion, squatting, or hypoxic spells may develop later.
Infants with acyanotic tetralogy of Fallot (pink tetralogy of Fallot) may be asymptomatic or may show signs of congestive heart failure (CHF) from a large left-to-right ventricular shunt.
Immediately after birth, severe cyanosis is seen in patients with tetralogy of Fallot and pulmonary atresia or severe pulmonary stenosis. These neonates may be ductal dependent and require urgent prostaglandin infusion to maintain ductal patency.
The natural history of untreated tetralogy of Fallot includes the following:
-
The degree of cyanosis is related to the severity of right ventricular (RV) outflow tract obstruction (RVOTO)
-
Infants with acyanotic tetralogy of Fallot gradually become cyanotic
-
Patients who are already cyanotic become more cyanotic than before as a result of worsening infundibular stenosis and polycythemia
-
Polycythemia develops secondary to cyanosis
-
A relative state of iron deficiency (ie, hypochromia) may develop; patients require monitoring for this condition
-
Hypoxic spells may develop in infants
-
Growth retardation may be present if cyanosis is severe
-
Brain abscess and stroke can occur but are rare
-
Subacute bacterial endocarditis is occasionally a complication
-
Aortic regurgitation may develop in some patients, particularly those with severe tetralogy of Fallot
-
Coagulopathy is a late complication of a long-standing cyanosis
Physical Examination
Varying degrees of cyanosis, tachypnea, and clubbing are present.
An increased right ventricular (RV) impulse along the left sternal border and a systolic thrill at the mid-left and upper-left sternal borders are commonly present.
An ejection click that originates in the aorta may be audible.
The S2 is usually single, because only the aortic component can be heard.
A long, loud (grade 3 to 5 or 6), ejection-type, systolic murmur is heard at the mid-left and upper-left sternal borders. This murmur originates from the pulmonary stenosis, but it may be easily confused with the holosystolic murmur of a ventricular septal defect (VSD). The more severe the RVOTO, the shorter and softer the systolic murmur.
In a neonate with tetralogy of Fallot, pulmonary atresia, and profound cyanosis, the heart murmur is either absent or soft, although a continuous murmur representing patent ductus arteriosus (PDA) may occasionally be audible.
In the acyanotic form, cyanosis is absent, and a long systolic murmur resulting from VSD and infundibular stenosis is audible along the entire left sternal border.
