Objectives To investigate the impact of blood pressure (BP) on the Doppler echocardiographic (Doppler-echo) evaluation of aortic stenosis (AS) severity.
Methods Handgrip exercise or phenylephrine infusion was used to increase BP in 22 patients with AS. Indices of AS severity [mean pressure gradient (ÄPmean), aortic valve area (AVA), valve resistance, percent left ventricular stroke work loss (%LVSW loss) and the energy loss coefficient (ELCo)] were measured at baseline, peak BP intervention and recovery.
Results From baseline to peak intervention, mean BP increased (99±8 vs. 121±10mmHg, p<0.0001), systemic vascular resistance (SVR) increased (1294±264 vs. 1552±372dyne∙s∙cm-5, p=0.0005) and mean transvalvular flow rate (Qmean) decreased (323±67 vs. 306±66ml/s, p=0.02). There was no change in ÄPmean (36±13 vs. 36±14mmHg, p=NS). However, there was a decrease in AVA (1.15±0.32 vs. 1.09±0.33cm2, p=0.02) and ELCo (1.32±0.40 vs. 1.24±0.42cm2, p=0.04), and an increase in valve resistance (153±63 vs. 164±74dyne∙s∙cm-5, p=0.02), suggesting a more severe valve stenosis. In contrast, %LVSW loss decreased (19.8±6 vs. 16.5±6%, p<0.0001) suggesting a less severe valve stenosis. There was an inverse relationship between the change in mean BP and AVA (r=-0.34, p=0.02); however only the change in Qmean was an independent predictor of the change in AVA (r=0.81, p<0.0001).
Conclusions Acute BP elevation due to increased SVR can affect the Doppler-echo evaluation of AS severity. However, the impact of BP on the assessment of AS severity depends primarily on the associated change in Qmean, rather than an independent effect of SVR or arterial compliance, and can result in a valve appearing either more or less stenotic depending on the direction and magnitude of the change in Qmean.
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