Therapy and Prevention - Congenital Heart Disease

The incidence and possible causes of paradoxical hypertension were evaluated in eight children who underwent balloon dilatation and seven children who underwent surgical repair of coarctation of the aorta. Both procedures resulted in a significant reduction in the coarctation gradient. Both systolic and diastolic blood pressures increased in the surgical group after repair, whereas systolic pressures decreased and diastolic pressures remained unchanged after balloon angioplasty. In the surgical group, but not in the balloon angioplasty group, plasma catecholamines and plasma renin activity rose during the first 2 days after relief of the coarctation. The data presented in this report support the hypothesis that the sympathetic nervous system and the renin angiotensin system are important mediators of the paradoxical hypertension that occurs after surgical repair of coarctation. Furthermore, balloon angioplasty of coarctation of the aorta does not stimulate either system and thus paradoxical hypertension is not a complication of this procedure. Circulation 75, No. 6, 1186-1191, 1987. IN CONTRAST TO other surgical procedures, severe hypertension commonly occurs during the first week after surgical repair of coarctation of the aorta.' Such paradoxical hypertension usually resolves after several days provided that the repair has been satisfactory, but it frequently requires intensive antihypertensive therapy during the early postoperative period. Both the sympathetic nervous system' 2, 5 6 and the renin angiotensin system' 7` have been implicated in the pathogenesis of paradoxical hypertension. Benedict et al.6 demonstrated that patients undergoing surgical repair of coarctation have a larger rise in plasma norepinephrine concentration than either normotensive or hypertensive patients undergoing other thoracic or abdominal surgical procedures. Rocchini et al.' demonstrated a marked increase in plasma renin activity in patients during the first week after coarctectomy compared with patients undergoing other cardiovascular surgery. More recently Gidding et al. 0 demonstrated that proFrom the Department of Pediatric Cardiology, C. S. Mott Children's Hospital, Ann Arbor, MI. Supported in part by NIH grant MO-1 RR-00042-21. Address for correspondence: Albert P. Rocchini, M.D., Pediatric Cardiology, C. S. Mott Children's Hospital, 1500 E. Medical Center Dr., Ann Arbor, MI 48109-0204. Received Dec. 11, 1986; revision accepted Feb. 25, 1987. 1186 pranolol treatment for 2 weeks before surgery and throughout the first postoperative week reduced the postoperative increase in plasma renin activity and prevented the development of paradoxical hypertension, although it did not affect the increase in plasma norepinephrine. Although these studies have demonstrated the importance of activation of the sympathetic nervous system in the pathogenesis of paradoxical hypertension, the mechanism of this activation remains unknown. Balloon angioplasty has recently been introduced as a nonsurgical technique for treating coarctation of the aorta. The purpose of the present investigation was to determine if either activation of the sympathetic nervous system or the development of paradoxical hypertension occur after balloon dilatation of coarctation of the aorta.