Usefulness of the indexed effective orifice area at rest in predicting an increase in gradient during maximum exercise in patients with a bioprosthesis in the aortic valve position

Authors: Pibarot, PhilippeDumesnil, Jean G.Jobin, JeanLemieux, MichelHonos, George; Durand, Louis-Gilles
Abstract: This study examines the hemodynamic behavior of aortic bioprosthetic valves during maximum exercise. Nineteen patients with a normally functioning stented bioprosthetic valve and preserved left ventricular function were submitted to maximum ramp bicycle exercise. In 14 of the 19 patients, valve effective orifice area and mean gradient were measured at rest and during exercise using Doppler echocardiography. At peak exercise (mean maximal workload 118 ± 53 W), the cardiac index increased by 122 ± 34% (+3.18 ± 0.71 L/min/m2, p <0.001), whereas mean gradient increased by 94 ± 49% (+12 ± 8 mm Hg, p <0.001), and effective orifice area by 9 ± 13% (+0.15 ± 0.22 cm2, p = 0.02). A strong correlation was found between the increase in mean gradient during maximum exercise and the valve area at rest indexed for body surface area (r = 0.84, p <0.0001). Due to the increase in valve area, the increase in gradient was less (-9 ± 7 mm Hg, -41 ± 33%, p = 0.0006) than theoretically predicted assuming a fixed valve area. These results suggest that the effective orifice area of the bioprostheses has the capacity to increase during exercise; therefore, limiting the increase in gradient. The relation found between the indexed effective orifice area at rest and the increase in gradient during exercise should be useful in predicting the hemodynamic behavior of a stented bioprosthesis during exercise. Previous studies have shown that many patients with an aortic bioprosthesis can have a relatively high transprosthetic pressure gradient despite a normally functioning valve.1, 2, 3 and 4 This is most often due to prosthesis–patient mismatch, which is defined as a disproportion between the size of the prosthesis and the patient’s body surface area. Despite this adverse hemodynamic condition, these patients do relatively well clinically, and there are only small differences in the medium-term prognosis of these patients when compared with patients without evidence of mismatch.2, 3 and 5 To explain this apparent discrepancy, we hypothesized that the behavior of the bioprosthesis during exercise might be different from that predicted from theoretical models1 and 4 and in particular, that the increase in gradient occurring in bioprostheses during exercise might be less than expected. To investigate this hypothesis, we performed Doppler echocardiographic studies of patients with a stented bioprosthesis in the aortic position at rest and during exercise.
Document Type: Article de recherche
Issue Date: 15 February 1999
Open Access Date: Restricted access
Document version: VoR
This document was published in: The American journal of cardiology, Vol. 83 (4), 542–546 (1999)
Alternative version: 10.1016/S0002-9149(98)00910-2
Collection:Articles publiés dans des revues avec comité de lecture

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