The significance of the residual blood pressure drop across the site of coarctation repair

Abstract

SirsStudies published in recent years have brought new insight into the blood pressure regulation in patients operated for coarctation of the aorta. However, the results are not consistent, which fuels the discussion on how blood pressure is best measured, what treatment is most efficient, and how the effect is best evaluated. The letter to the Editors in the present issue, from Vriend and Mulder (2005), is an important contribution to this discussion.As part of our follow-up program of patients operated for coarctation of the aorta, their exercise capacity was studied (Instebø et al. 2004). Most of these patients had dropped out of the program (Thu et al. 1999). Although some had a significant sustained hypertension, none was on antihypertensive medication. Vriend and Mulder ask for our surgical results following coarctation repair. We have previously published these data (Thu et al. 1999). A total number of 102 patients were operated for coarctation of the aorta in our hospital during the period 1975-1995. Eighteen patients died, of whom six died within 30 days after the surgery and 12 later. Among these patients, 11 had associated congenital heart defects. Four were re-operated. Three had balloon dilatation.In the new guidelines from the European Society of Cardiology (2003), re-intervention is recommended for patients with a resting blood pressure gradient of 30 mmHg or more. These guidelines had not been published when our study was accepted for publication. In addition, the evidence for the recommendation has not been reported.We studied how the resting drop in blood pressure across the coarctation site is associated with the resting blood pressure and exercise capacity, measured by aerobic phase and maximal oxygen consumption.A pressure drop of more than 20 mmHg (2.67 kPa) is associated with hypertension at rest, and with an increased blood pressure drop during exercise and with reduced exercise capacity. However, we did not find an association either between the resting blood pressure and the resting drop in blood pressure or peak blood pressure during exercise. This is in accordance with a recent study by Swan et al. (2003), who reported a lack of correlation between peak blood pressure during exercise and an increased repair site gradient. Vriend et al. (2003) studied how, on the one hand, the mean daytime systolic ambulatory blood pressure is correlated to the peak blood pressure during exercise and, on the other hand, how it is correlated to resting systolic blood pressure. This does not necessarily imply any correlation between resting blood pressure and peak systolic blood pressure during exercise or the blood pressure drop across the repair site at rest or during exercise. We did not find such an association in our study.A major problem in our study was the highly variable resting blood pressure in many patients. However, an elevated peak systolic blood pressure during exercise seems to predict an elevation of the mean systolic daytime blood pressure.In summary, our data suggest that a blood pressu...