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Misra et al. Vessel Plus 2022;6:32 https://dx.doi.org/10.20517/2574-1209.2021.104 Page 11 of 13

CARDIAC CATHETERIZATION IMAGING FOR EVALUATION OF REPAIRED TOF
Diagnostic role
Cardiac catheterization has redefined its role since the advent and advancement of other imaging modalities
of noninvasive nature such as echocardiography, CMR, CT scan. Cardiac catheterization is no longer the
primary diagnostic modality though it assumes an important role when along with diagnostic components,
therapeutic intervention is desired [37,38,39] . This could include dilation of pulmonary artery/conduit, stent
placement, percutaneous pulmonary valve placement, coiling of aorto-pulmonary collaterals, and closure of
residual septal shunts and or coronary artery intervention. With the increase in the number of adult patients
with repaired TOF and they are advancing age, coronary artery assessment/interventions may assume a
disproportionately increased role. Inherently, hemodynamic data at various levels in the heart/great
vessel/conduit allows assessment of narrowing in the vascular structures, residual shunt by oximetry,
diastolic function by pressure measurement, and cardiac index by oximetry/thermo-dilution method. As a
result, pulmonary vascular resistance and systemic vascular resistance can be calculated. Angiography
allows the assessment of degree of valvular narrowing or regurgitation in addition to aorto-pulmonary
collateral and great vessel anatomy such as pulmonary artery stenosis, aortic root dilation, aneurysm
formation, pseudo-aneurysm formation or dissection. Angiography also allows visual assessment of
ventricular function and residual shunt.

Advantages
Cardiac catheterization is the gold standard modality of imaging in patients with repaired TOF when it
comes to measurement of hemodynamics such as pressures inside the heart and great vessels (aorta and
pulmonary arteries/conduit), course of coronary arteries in relation to right ventricular outflow tract and
the impact on the coronary lumen from percutaneous valve implantation. It is definitely a modality of
choice for intervention for branch pulmonary arteries, if needed coronary arteries and if percutaneous
valves are feasible. This is the only imaging modality that can be therapeutic in nature.

Limitations
Need for venous/arterial access with floating of intra-cardiac catheters, devices, stents, coils makes it
invasive in nature with the potential for complications related to invasive nature. High cost, need for
sedation/anesthesia/intubation, exposure to ionizing radiation, increasing the risk of carcinogenesis, and
need for training and expertise in the field are some of the other limitations.

CONCLUSIONS
Long-term prognosis of patients with repaired TOF fulcrums on optimal outpatient surveillance due to high
incidence of residual anatomic and hemodynamic sequelae and need for re-intervention. We have reviewed
the commonly used and available imaging modality in terms of the role it plays, questions it can answer,
and limitations. It is clear that the various available diagnostic tools are not exclusive of each other but
complementary. A diagnostic tool can be selected depending on the age of the patient, clinical
[9]
circumstances, questions to be answered, and institutional preferences/expertise . Hence a multimodality
approach is recommended. Younger patients who are less than 10 years of age may not be able to cooperate
for a CMR, while echocardiography may provide excellent images and all the required information. A CMR
may be more appropriate for older patients who may require a quantitative assessment of the right
[19]
ventricle/pulmonary insufficiency . Those with contraindications for CMR may utilize CT scan as an
option keeping in mind the increased risk of cancer due to exposure to ionizing radiation. Nuclear scan can
be beneficial to calculate the differential flow to the lungs when CMR fails to provide that information. This
could be related to artifacts from previously placed coils/metal. Once again, we have to be cognizant of the
radiation exposure and risks involved. Cardiac catheterization may not only be used as a diagnostic tool but
will have the advantage of performing therapeutic interventions at the same time and can prove extremely