Physiological assessment of renal artery stenosis: Comparisons of resting with hyperemic renal pressure measurements

Abstract

Renin production, an index of renal ischemia, was markedly greater at hyperemia than at rest, suggesting that RAS, with either an HSG of 21 mm Hg or a renal FFR of 0.90, can be considered a hemodynamically significant stenosis. Intrarenal papaverine neither prolonged the QT interval nor induced ventricular arrhythmias and the safety of which will need to be corroborated in a large study. © 2010 Wiley-Liss, Inc.

Can we apply coronary physiologic methods to renal artery stenosis assessment?

“…The new finding in the report of Kapoor et al [3] besides reproducing the findings of De Bruyne et al [4] is the effect of intra renal papaverine on the ECG. Intracoronary papaverine is no longer used for coronary hyperemia because of QT prolongation and Torsade de Pointe but as Kapoor et al [3] demonstrated it has no electrocardiographic effects when given intrarenally likely due to the dilution effect before the drug reaches the heart.…”

“…Nonetheless, the application of a measurable endpoint of significant renal artery pathophysiology is preferable to prior statements on what constituted a significant narrowing. Despite the use of different hyperemic agents, both studies [3,4] had similar renal FFR cut points suggesting reduced blood pressure and maintained or improved renal function should follow stenting of these lesions. Long-term clinical correlations validating this postulated benefit are underway.…”

“…The renal FFR calculation was made exactly like coronary FFR. In this issue, Kapoor et al [3] also report a renal FFR with a threshold of <0.90 or a hyperemic stenosis gradient of >21 mmHg as significant and associated with a dramatic increase in renal vein renin activity (RVRA) compared with renal FFR of >0.93 or hyperemic stenosis gradient of <16 mmHg. These data were acquired in 55 patients with renal artery stenosis, in whom the resting ratio between distal renal pressure to the aortic pressure (Pd/Pa ratio), renal FFR, and resting and hyperemic systolic gradients (RSG and HSG, respectively) were measured.…”

“…The report of Kapoor et al [3] is another of a continuing series attempting to establish an objective test to support an ad hoc indication for renal artery stenting. Both Kapoor et al [3] and De Bruyne et al [4] used elevations of RVRA as a marker of renal ischemia.…”

“…Both Kapoor et al [3] and De Bruyne et al [4] used elevations of RVRA as a marker of renal ischemia. Unlike coronary FFR, renal FFR has been particularly difficult to validate as the clinically established gold standard of stress-induced ischemia may not be culled from simple renin activity data alone.…”