Evaluation of the hypertensive infant: a rational approach to diagnosis.

This article reviews the literature and describes a methodologic approach to the diagnosis of hypertension in the young infant. The numerous etiologies of hypertension have been discussed and normative blood pressure data for neonates and infants have been provided. Techniques for accurate blood pressure measurement in the intensive care setting and for routine outpatient settings, are discussed. The lengthy discussion of radiologic approach to imaging can be summarized with the following suggested algorithm. Initial screening should be performed with gray-scale sonography, to identify renal parenchymal or collecting system abnormalities, including mass lesions and congenital anomalies. Further imaging with color and duplex Doppler sonography detects renal arterial or aortic thrombosis, and alterations in the arterial waveform caused by intrinsic or extrinsic renal artery narrowing. The major limitation of Doppler sonography is the recognition that disease in accessory renal arteries or in small segmental intrarenal arteries may frequently be undetected. Functional imaging with ACEI renography should follow renal sonography to detect hemodynamically significant renovascular disease (with a sensitivity and specificity of approximately 90%); intravenous enalaprilat is the preferred ACEI. Angiography should be reserved for older children in whom interventional percutaneous angioplasty may be more feasible. A young infant with hypertension caused by renal artery stenosis should be controlled medically until he or she is large enough to undergo angiography and angioplasty successfully. CT angiography and MR angiography, although promising in the adult population, may not adequately resolve the small intrarenal vessels, which are frequently the culprit in renovascular hypertension of infancy.