Fetal congenital midaortic syndrome with unilateral renal artery stenosis prenatally presenting with polyhydramnios and postpartum as hyponatremic hypertensive syndrome

The midaortic syndrome (MAS) is a rare anomaly, characterised by narrowing of the distal aorta and its major branches. The most common symptom is severe arterial hypertension. The combination of hyponatremia, polyuria and renovascular hypertension caused by a unilateral renal artery stenosis is described as hyponatremic hypertensive syndrome. We report a case of MAS with unilateral renal artery stenosis in a preterm female neonate. A pregnant woman at 34 weeks of gestation was referred with fast growing abdominal circumference and pain. The ultrasound revealed severe polyhydramnios and fetal myocardial hypertrophy. Within the first 48 hours of the neonatal period, the diagnosis of MAS was made. We conclude that symptomatic MAS, caused by unilateral renal artery stenosis, resulting in increased renin–angiotensin–aldosterone system activity and subsequent polyuria of the non-stenotic kidney, lead to clinically significant polyhydramnios.

A pediatric patient with hyponatremic hypertensive syndrome without persistent hypertension in acute phase: A case report and review of literature

Hyponatremic hypertensive syndrome is characterized by hypertension, hyponatremia, and hypokalemia due to unilateral renal artery stenosis. We herein report a 1-year-old hyponatremic hypertensive syndrome infant without persistent hypertension in the acute phase. On the ninth hospital day, his systolic and diastolic blood pressure increased up to 154–160 and 70–84 mmHg, respectively. Acute gastroenteritis and dehydration might transiently mask his hypertension. By percutaneous transluminal balloon angioplasty for right renal artery, his blood pressure finally normalized without antihypertensive drugs. We reviewed 23 previously reported pediatric patients with hyponatremic hypertensive syndrome under the age of 15 years. Including our patient, there are only three reports on hyponatremic hypertensive syndrome without persistent hypertension in the acute phase. Hyponatremic hypertensive syndrome is curable with proper diagnosis and timely intervention. Therefore, pediatricians should pay attention to the signs and symptoms associated with hyponatremic hypertensive syndrome, even if persistent hypertension was absent in the acute phase.