Coarctation hypertension is renovascular, modified by ambulation. Coarctation hypertension renovascular variant

In coarctation, bipedal exercise induces a pressure triad: exaggerated systolic arm hypertension, unchanging leg pressure, and markedly increased systolic gradient. Constancy of leg pressure derives from the lower body sharing the poststenotic compartment with the kidneys. Exercise-induced poststenotic hypotension stimulates the juxtaglomerular apparatus (JGA) to raise renal pressure to pre-exercise levels. Ambulation during the greater part of each day stimulates the JGA repetitively. Thereby, this chronic Single-Kidney-Goldblatt model is modified by increased plasma renin, fluid volumes, and cardiac output. It also accounts for hyper-responsive renin output after renin blockage and for mild poststenotic hypertension. Hypertension after repair which corrected the resting gradient, is almost always associated with the exercise triad, indicating that renal ischemia exists during ambulation. Thus, residual hypertension usually means residual coarctation. Mesenteric ischemia complicating postoperative paradoxic hypertension is probably due to spasm in the superior mesenteric artery and not to fixed occlusion of necrotizing arteritis.