Cath Lab Digest

Congenital Heart Disease
Accurate measurement of gradients is important in children with valve disease and in congenital lesions, since valve area may change with patient size, and decisions to intervene are often based on gradient alone.
Coarctation of the aorta is a difficult lesion to assess hemodynamically. In some cases, even if the coarctation is not very tight, it may be eccentric. It is sometimes a struggle to cross the coarct lesion with anything but a wire. Figure 14 is a case where there is a 20 mm gradient across the coarctation segment. The patient is symptomatic, with leg fatigue with modest activity. Interpretation of the gradient is challenging in the de novo coarctation because collaterals can be so good that there may be almost no gradient across a virtually occluded aorta.

Recently, percutaneous valve replacement in pulmonary artery (Fontan) conduits has been performed in congenital heart disease patients with stenosis in their bioprosthetic valves.8 Figure 15 is a case in which it was impossible to get a catheter beyond the conduit inlet into the distal PA conduit. Properly assessing whether the prosthetic valve in these pulmonary artery conduits is or is not functioning is essential for proper management. Reoperations may be a second, sometimes a third or a fourth procedure for these patients. In Figure 15, a conventional catheter could not be passed into the distal pulmonary conduit, but a 0.014” pressure wire could be placed relatively easily. There is a large gradient, indicating severe pulmonic prosthetic stenosis, which warrants intervention.

Conclusions
The application of translesional pressure gradient assessment has been well studied in the coronary circulation, and fractional flow reserve measurement has become a routine part of practice largely due to the ability to place a pressure wire into the coronary circulation. Limitations on pressure gradient measurement that were common when only standard fluid-filled catheters were available have been overcome by pressure wire technology. Gradient measurement in renal artery stenosis and other peripheral lesions, and in valvular and congenital heart diseases, can solve a wide variety of both mundane and unusual clinical problems.

Address for correspondence: Ted Feldman, MD, FSCAI, FACC, Professor of Medicine, Northwestern University Medical School; Director, Cardiac Catheterization Laboratory, Evanston Hospital, Cardiology Division, Burch 300, 2650 Ridge Ave., Evanston, IL 60201. E-mail: TFeldman@enh.org