Pectus - Preoperative Assessment - Radiology and Cardiac Evaluation

Pectus excavatum repair is arguably the most painful operation that could be done in a child.

The Cincinnati Children's approach is selective in identifying patients who will benefit from surgery and emphasizes helping patients and parents deal with pain and discomfort, minimizing workup risks (ionizing radiation), and mitigating chronic pain and substance abuse risk.

Standard preoperative workup includes cardiac MRI, genetics referral for connective tissue evaluation, and allergy testing (particularly for nickel and vanadium in bar materials).

Patients with connective tissue disorders and hyperflexibility may be at higher risk for chronic pain after pectus repair.

Depending on the phase of respiration, the Haller index can change—some patients have abnormal indices at end expiration but normal indices at end inspiration despite clinical pectus excavatum.

Haller found that patients with a Haller index greater than 3.25 were ones he operated on, but this was an observational retrospective study, not a rigorous scientific or prospective study.

There is a very large overlap between patients with normal chests and patients with pectus excavatum regarding Haller indices—normal patients can have technically abnormal Haller index without pectus, and vice versa.

The correction index (greater than 10%) shows no overlap between normal and abnormal patients, unlike the Haller index.

The depression index (greater than 0.2) accounts for variable chest shapes (barrel-shaped versus elliptical) and should be abnormal in pectus excavatum regardless of chest configuration.

Cardiac MRI can replace CT and echocardiogram, providing anatomical and functional evaluation without contrast in approximately 25 minutes.

Cardiac MRI allows screening for valve disease and aortopathy, both part of the connective tissue spectrum, in addition to assessing pectus anatomy and cardiac function.

Echocardiogram image quality in most pectus patients is atrocious—you can't see much of anything because the right ventricle and sternum are in the very near field of the transducer.

Approximately 15% of pectus patients had right ventricular ejection fractions less than 50% (normal is 50%).

Patients with RV compression had depressed right ventricular ejection fractions, particularly when compression affected the free wall versus the groove between right atrium and right ventricle.

Kids can have right ventricular ejection fractions in the 40s and be asymptomatic; symptoms often don't manifest until very late in the disease process.

As kids with pectus age, the heart appears to get extruded into the left chest, though whether this is a growth developmental phenomenon is unknown.

Children tolerate MRI very well; video goggle technology allows them to watch movies during the procedure, relieving anxiety.

MRI can be performed with pectus bars in place; there may be small localized susceptibility artifacts where the bar is on top of the heart, but they are minimal.

Insurance companies require some metric (abnormal pectus index plus evidence of cardiac dysfunction or abnormality) to approve coverage; providing multiple indices (Haller, correction, depression) plus cardiac dysfunction evidence has been effective in reversing denials.

The earlier you get a CT and the higher the dose, the greater your long-term risk of developing malignancy; pediatric tissues divide more rapidly and have more time to develop DNA breaks.

A standard CT dose for pectus can deliver about 7 millisieverts of radiation, equivalent to about 2 years of background radiation in one scan.

There is data suggesting an increased risk of malignancy long term from even one CT, and the younger you are, that risk increases over your lifetime.

When operating on younger patients, bars need to be shorter (not extending to mid-axillary line) to avoid impeding chest wall growth.