Pressure recovery in pediatric aortic valve stenosis

Abstract

This study was designed to evaluate the phenomenon of pressure recovery in pediatric patients with aortic stenosis and also to evaluate how observed differences between catheter and Doppler gradients can be predicted by Doppler echocardiography. Doppler measurements of aortic valve stenosis gradients are known to overestimate observed gradients in the catheterization laboratory. Pressure recovery has been shown to be a contributing factor to this discrepancy. However, the clinical relevance of correcting Doppler gradients using the pressure recovery equation has not been evaluated in the pediatric population. Simultaneously obtained catheter and Doppler gradients were studied in 14 patients (range, 0.03-18 years; mean, 4.1 years) with aortic valve stenosis. A total of 23 data points were measured because 9 patients underwent balloon valvuloplasty and had both a pre- and a post-balloon valvuloplasty data point in the study. The catheter gradients were then compared to peak, mean, and pressure recovery corrected Doppler gradients. Pressure recovery was calculated using a previously validated equation. As expected, measured echocardiographic continuous-wave peak Doppler gradients overestimated the observed catheter gradients (range, 16-93 mmHg; mean, 43 mmHg). The continuous-wave peak Doppler gradients, mean, and pressure recovery adjusted gradients were equally as good in correlating the observed catheter gradients to those obtained by Doppler echocardiography (r = 0.92). However, pressure recovery corrected Doppler gradients were in better agreement with catheter gradients than echocardiographic mean or peak Doppler gradients (95% limit of agreement: -9 to 19 mmHg for pressure recovery corrected gradients, -30 to 11 mmHg for mean Doppler gradients, and 2-83 mmHg for peak Doppler gradients). Measured continuous-wave peak Doppler gradients consistently overestimated catheter gradients. The noted differences may be predicted using the pressure recovery equation. Pressure recovery is a significant factor in children with aortic valve stenosis.