Prediction of recurrent coarctation by early postoperative blood pressure gradient

OBJECTIVE

Blood pressure gradients that are noted early after repair of coarctation in neonates and infants are often attributed to proximal arch hypoplasia. Rapid growth of the hypoplastic proximal arch is usually observed, although in some individuals an early gradient predicts the subsequent need for reintervention. To define the predictive reliability of blood pressure gradients between arms and legs and to identify predictors of arch growth, we undertook a retrospective study.

METHODS

Between January 2000 and June 2008, 77 infants underwent surgical repair of coarctation. Data collected included preoperative dimensions of aortic segments. Blood pressure gradients between arms and legs determined by cuff were compared intraoperatively and postoperatively, as well as 2-dimensional echocardiographic dimensions of the aorta between those who did not require reintervention for recoarctation (group A) and those who did (group B). Receiver operating characteristic curve analysis was applied to evaluate discrimination of the systolic gradient in differentiating the 2 groups of patients.

RESULTS

At surgery, patients' median age was 10 days and weight was 3.3 kg. There was 1 early death. Median follow-up was 40 months (interquartile range, 24-63 months). Recoarctation developed in 11 patients (14.3%), defined as a resting blood pressure gradient of greater than 20 mm Hg with a corresponding decrease in the diameter of the aorta by 50%. Freedom from recoarctation was 87% at 1 year and 85% at 5 years. Multivariable logistic regression analysis identified the size of the ascending aorta as a risk factor for recoarctation. Blood pressure gradient at the end of surgery was not predictive of recoarctation. The ascending aorta and transverse arch showed rapid growth in group A, and this was associated with a decrease in blood pressure gradient over time. In comparison, the growth of the ascending aorta and arch in group B was significantly less than in group A and associated with worsening of gradients. Receiver operating characteristic curve analysis revealed that gradients at the time of hospital discharge (>13 mm Hg) had excellent discriminative accuracy in identifying patients in whom subsequent recoarctation developed.

CONCLUSIONS

Small size of the ascending aorta is a risk factor for recoarctation. Limb gradient in the operating room at completion of surgery is not a reliable tool to assess repair of coarctation, although the gradient at the time of hospital discharge can be used to accurately predict recoarctation. Rapid growth of both the ascending and the transverse aorta is frequently observed and associated with improvement in gradients over time.