Renal fractional flow reserve: A hemodynamic evaluation of moderate renal artery stenoses

Abstract

The objective of this study was to perform a hemodynamic evaluation of moderate (50-90%) renal artery stenosis (RAS) under conditions of rest and maximum hyperemia. Identifying patients with RAS who have hemodynamically significant stenoses and are most likely to benefit from revascularization is clinically important. Current methods used to evaluate RAS, including angiography, have limitations. Physiologic evaluation of RAS may have a role in identifying patients with hemodynamically significant stenosis. Patients with suspected renovascular hypertension due to aorto-ostial RAS were included in the study. Hyperemia was induced by administration of intrarenal papavarine. Translesional pressure gradients were measured and renal fractional flow reserve (FFR) was calculated using a 0.014'' pressure guidewire. Thirteen patients and 14 arteries with moderately severe (50-90%) RAS were studied. The mean translesional pressure gradient rose from a baseline of 6.3 +/- 3.9 to 17.5 +/- 10.8 mm Hg with maximal hyperemia. The renal FFR ranged from 0.58 to 0.95. There was a poor correlation between angiographic stenosis measurement and the renal FFR (r = -0.18; P = 0.54) and the hyperemic translesional mean pressure gradient (r = 0.22; P = 0.44). There was an excellent correlation between renal FFR and the resting mean translesional pressure gradient (r = -0.76; P = 0.0016) and the hyperemic mean translesional pressure gradient (r = -0.94; P < 0.0001). Selective renal arterial papavarine administration induces maximum hyperemia, permitting the calculation of renal FFR in renal arteries with aorto-ostial stenoses. The renal FFR correlates well with other hemodynamic parameters of lesion severity, but poorly with angiographic measures of lesion severity.

Prognostic value of renal fractional flow reserve in blood pressure response after renal artery stenting (PREFER study)

“…First of all, we used only papaverine bolus as hyperemic stimulus. 30 mg of papaverine as adequate dose in achieving of maximal hyperemia was previously proved [13]. Mangiacapra et al [22] used not only papaverine but also dopamine in hyperemia inducement.…”

“…The utility of Pd/Pa ratio and rFFR as diagnostic tools in RAS assessment was demonstrated in only several trials [13][14][15][16]. Thus, the evaluation of its potential prognostic value in hypertension response after renal revascularization was urgently required.…”

“…During previous years several studies focused on physiological assessment of RAS with intrarenal pressure measurements. Both resting pressures ratio, called "Pd/Pa ratio", and hyperemic renal fractional fl ow reserve (rFFR), after papaverine or dopamine administration became helpful diagnostic tools [13][14][15][16]. First studies suggested also that translesional systolic pressure gradient and rFFR may predict the outcome after renal revascularization.…”

Fractional flow reserve guided renal artery angioplasty – a new method of optimal patient selection?

“…If we take into consideration the fact that many authors use vasodilators to estimate the importance of renal artery stenosis, we can find that the majority of researchers consider this kind of measurement to be useful [9][10][11][12]. In recently published reports there has been growing evidence of the usefulness of fractional flow reserve (FFR) in patient qualification for percutaneous transluminal renal angioplasty (PTRA).…”

The Need for Randomized Trials to Prove the Safety and Efficacy of Parachutes, Bulletproof Vests, and Percutaneous Renal Intervention

“…Even with quantitative measurement, angiography is unable to discriminate between nonobstructive and significant ARAS (Figure). 17 One solution that would improve patient selection for PRI is hemodynamic assessment of ARAS. Hemodynamic confirmation of severity of angiographic lesions can be accomplished by placing a small nonobstructive catheter (≤3 F) or a micromanometertipped pressure measuring guidewire (0.014-in) across the renal artery stenosis to measure a simultaneous translesional pressure gradient.…”