Coarctation of the aorta is a cause of right arm hypertension in children and of heart failure in infants after ductal closure. We present two cases with these presentations that were initially thought to be coarctation of the aorta. They were subsequently diagnosed as Takayasu's arteritis in the older child and a large cerebral arteriovenous malformation in the infant. These conditions should be in the differential of right arm hypertension and of aortic flow reversal on echocardiography.