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Page 2 of 13 Misra et al. Vessel Plus 2022;6:32 https://dx.doi.org/10.20517/2574-1209.2021.104

[2,3]
years . In the current era, with the advances in diagnoses and management, survival of patients with
[4,5]
repaired TOF exceeds 98% in the first year, and 30-year survival approaches 90% . This has led to an
interesting phenomenon where the adult survivors of this condition outnumber the incidence of children
[6]
with this condition . Today, TOF is one of the most common diagnoses seen in an adult congenital clinic.
Under optimal conditions, complete repair of TOF is performed during infancy, while some of the patients
may require a palliative procedure such as a systemic to pulmonary shunt, most likely a modified Blalock-
Taussig shunt prior to complete repair. Despite a complete repair at an optimal time, almost all patients
with TOF will have residual anatomic and hemodynamic sequelae that will require follow-up and or
intervention at a later time . This makes lifelong surveillance imperative for this group of patients.
[7,8]

Several imaging modalities are available for the purposes of surveillance [9,10,11,12] . The commonly used
diagnostic tools include echocardiography, cardiac computed tomography (CT), cardiac magnetic
resonance imaging (CMR), cardiac catheterization, and nuclear scan. None of the diagnostic tools
mentioned here stands perfect in isolation in terms of obtaining all the necessary information. A tailored
multimodality approach is needed to identify anatomic and functional abnormalities, assess the degree of
severity, and associated abnormalities to help the clinical decision making.

In this review, we will discuss the role of each of the imaging modalities mentioned above, along with its
advantages and limitations. We will also focus on repaired TOF patients.

ECHOCARDIOGRAPHIC IMAGING FOR EVALUATION OF REPAIRED TOF
Diagnostic role
Echocardiography is the mainstay of imaging of the patient with TOF. An experienced operator can obtain
valuable information regarding the physiology of a patient with repaired TOF, which can be used to guide
clinical management . The echocardiogram provides valuable qualitative information regarding right
[13]
ventricular (RV) size and function as well as pulmonary regurgitation.

Clinical information
[12]
Evaluation of a new patient with a history of Tetralogy of Fallot typically starts with an echocardiogram .
Based on the clinical status of the patient, a routine transthoracic echocardiogram should be obtained at
least every 1-2 years . Transesophageal echocardiogram is utilized for peri- and post-operative evaluation
[12]
of the right ventricular outflow tract (RVOT) and pulmonary valve in patients undergoing surgical revision
of their cardiac lesion.

Repair of Tetralogy of Fallot typically consists of patch closure of the ventricular septal defect (VSD),
resection of muscle bundles that are obstructing the RVOT, and transannular patch repair, in which the
RVOT is augmented in order to provide adequate forward pulmonary blood flow. A sequela of this
procedure is that patients can develop significant pulmonary regurgitation over time, leading to RV volume
overload [Figure 1] and free pulmonary insufficiency [Figure 2, Video 1].

The key elements of the echocardiographic evaluation of the patient with repaired TOF include evaluation
of the RV size and function, measurement of the severity of obstruction and/or regurgitation of the
[13]
pulmonary valve, as well as the measurement of right ventricular systolic pressure . Fractional area change
(FAC) and tricuspid annulus plane systolic excursion (TAPSE) have been shown to correlate with Magnetic
Resonance Imaging (MRI) measurements of ejection fraction, with one study suggesting a FAC < 40% or a
TAPSE < 17 mm correlated with RV ejection fraction < 47% on MRI . For PR, there is some evidence that
[14]
the ratio of the pulmonary regurgitation jet width to the valve annulus can correlate with MRI