ARM-ANKLE SYSTOLIC BLOOD-PRESSURE DIFFERENCE AT REST AND AFTER EXERCISE IN THE ASSESSMENT OF AORTIC COARCTATION

Objective-To evaluate the difference in systolic blood pressure at the arm and ankle at rest and after various exercise tests for the assess ment of aortic coarctation. Methods-22 patients (mean age 33 years, ra nge 17-66) were investigated on the suspicion of having haemodynamical ly significant aortic coarctation. Eight had undergone previous coarct ation surgery, of whom five had received vascular grafts and three end to end anastomoses. The patients exercised submaximally while supine, seated on a bicycle, and walking on a treadmill, as well as exercisin g maximally on a treadmill. Arm and ankle blood pressure were measured with a cuff at rest and 1-10 minutes after exercise. Invasive pressur es and cardiac output by thermodilution were recorded during catheteri sation while patients were at rest and during and after supine bicycle exercise. The degree of constriction was assessed by angiography. Twe lve healthy volunteers (mean age 32 years, range 17-56) provided refer ence values for cuff pressures after exercise.Results-All patients wit h a difference in cuff pressure at rest of 35 mm Hg or more had a diff erence in invasive pressure of 35 mm Hg or more. Increasing severity o f constriction on angiography correlated with larger pressure gradient s at rest and during exercise (P < 0.0001). When cuff measurements aft er exercise were considered singly or combined to form a predictor the y did not improve the prediction of the invasive pressure gradients at rest or after maximal exercise. A pressure gradient between arm and a nkle also developed in normal subjects after maximal but not after sub maximal exercise. Conclusion-In most patients with suspected haemodyna mically significant coarctation the difference in cuff pressure betwee n arm and ankle at rest is sufficient to select patients in need of fu rther evaluation. If exercise is performed submaximal exercise is pref erable.