Isotope renograms, using radiohippuran, were carried out in a series of 569 hypertensive patients. In 20 patients with active renal artery stenosis, i.e. with renal ischaemia, three types of renogram abnormality were found: the C type of curve, in which there was a delay in the fall of radioactivity during the excretory phase, was present in nine patients; seven patients had a B type of curve in which there was a lowering of the peak level of radioactivity with a delay in fall during the excretory phase; and four had an A type of curve, in which there was a reduced vascular spike with flattening of the secretory and excretory phases.The effect of hydration and dehydration on the renogram pattern is described, and the relationship between the renogram pattern and the severity of stenosis together with renal parenchymal changes discussed. The value of the renogram in the assessment of the significance of a renal artery stenosis demonstrated by aortography, and its value in the follow-up of patients following reconstructive vascular surgery is discussed. It is pointed out that misleading results may be obtained in segmental ischaemia, bilateral stenosis, and where an unrelated renal lesion coexists with a renal artery stenosis.In conclusion, it is suggested that the isotope renogram, when used in conjunction with an intravenous pyelogram, is a safe and effective screening procedure for use in the detection of renovascular hypertension.
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