The usefulness of renal vein renin studies in hypertensive children: a 25-year experience

Abstract

Lateralised renin secretion predicts improvement following surgery/angioplasty of the affected kidney in paediatric hypertension. We retrospectively analysed all our renal vein renin (RVR) studies undertaken in hypertensive children and their subsequent clinical outcomes over a 25-year period. The outcomes were categorised as cure, improvement or no change in hypertension. The proportions that benefited by 'following' or 'ignoring' the RVR results in relation to the aetiology of hypertension and subsequent therapy were compared. A ratio between the RVR value of the dominant kidney and that of the contralateral kidney (R/Rc ratio) above 1.5 was considered to show significant lateralisation. A ratio between RVR value of the contralateral kidney and that of the caudal inferior vena cava (Rc/P ratio) of less than 1.3 was considered to indicate contralateral renin suppression. Of 233 RVR records, 137 were suitable for analysis. Of these, 39 had reflux nephropathy (RN), 73 renovascular disease (RVD) and the others miscellaneous conditions. Of the 39 hypertensive children with RN, the R/Rc ratio was over 1.5 in 20 subjects, of whom 11 underwent surgery. Amongst the 19 with an R/Rc less than 1.5, 4 also had surgery. Of the 73 hypertensive children with RVD, the R/Rc ratio was over 1.5 in 38 subjects, of whom 20 underwent surgery/angioplasty. Amongst the 35 with an R/Rc less than 1.5, 7 also underwent surgery/angioplasty. In RN there was no significant difference in the proportion that improved with allocated treatment, as suggested by the 'test' when compared with those who were 'misallocated'. In RVD, however, the proportion improved (35.0%) by 'following the test' (i.e. R/Rc ratio) was significantly greater than the proportion improved (12.5%) in the group in whom the test was 'ignored'. This was true for both R/Rc and Rc/P ratios. Thus, RVR measurements are useful for identifying hypertensive children with RVD that may have a favourable outcome after surgery, but this does not apply to children with RN. Measurements, however, may have diagnostic value even if surgery or angioplasty is not anticipated.

A diagnostic approach for the child with hypertension

“…Other specific diagnostic procedures are also available to investigate affected individuals [44,47], but experience in their use in children is limited. Nonimaging tests include measurement of peripheral plasma renin activity [48], the captopril test [49] and renal vein renin sampling [50], all of which have inherent limitations. ACE inhibition renal scintigraphy has been proven to be a useful initial screening test [51,52].…”

“…They include MR angiography [53], spiral CT scan angiography [54], renal vein renin studies [50], renal angiography [55], MIBG scanning [62], venous catecholamine sampling, somatostatin receptor imaging by 111 In-octreotide scan [62], cerebral isotope scan, cerebral angiography and newer molecular genetic studies for identifying genetic syndromes [63].…”

The utility of renal venous renin studies in selection of patients with renal artery stenosis for angioplasty

“…On the contrary and more recently, an RVRR of at least 1.55 was found to be useful in identifying patients with RAS more than 70% who benefit from revascularization, while a ratio greater than 1.72 was found to be associated with good outcomes from nephrectomy when renal artery occlusion was present [8]. Other studies also found that lateralization of renin secretion normalized after revascularization [42], that a negative RVRR was predictive of absence of improvement [43] and RVRs were useful in assessing children with RAS [44].…”

Hypertension Caused by Renal Arteriovenous Fistula

“…However, it may be difficult to distinguish arteriovenous fistula from aneurysm at color Doppler US, and flow in normal vessels grouped in the renal hilum obscures lighter-colored flow in a small central renal AVF. Although other diagnostic imaging tools might be helpful, angiography remains the standard of reference for confirming or excluding the existence of renal AVF, and selective segmental renal vein renin sampling is invaluable for locating the renin producing lesion 6-8)…”