Key result
In vitro testing of prosthetic aortic valves showed pressure recovery slopes were significantly higher in smaller valves (P<0.01), bioprosthetic valves (P<0.001), and at higher flows (P<0.0001).
Why the study?
How do valve type, size, and flow rate affect errors in pressure gradient measurement due to pressure recovery in prosthetic aortic valves in vitro?
How do valve type, size, and flow rate affect errors in pressure gradient measurement due to pressure recovery in prosthetic aortic valves in vitro?
Pressure recovery causes significant errors in catheter pressure gradient measurements, particularly in smaller, bioprosthetic valves at higher flow rates, which clinicians must consider during diagnostic evaluations.
May inform gradient interpretation in small bioprosthetic valves at high flow; hypothesis-generating pending in vivo validation.
We assessed errors in valvular pressure gradients due to pressure recovery, the variation in aortic pressure with distance from the valve, to explain errors in catheter measurements and simultaneous continuous‐wave Doppler/catheter studies. Ten types and three sizes of valves were tested in vitro. Aortic pressure was measured by catheter between 1 and 6 cm from the valve. Pressure recovery was quantified as the slope of the gradient with distance from the annulus. Valve type, size, and flow rate effects were determined by analysis of variance. Relationships between Doppler and maximal catheter gradients were also analyzed statistically. The slope of pressure recovery was significantly higher in smaller valves (P< 0.01), in bioprosthetic rather than mechanical valves (P < 0.001), and at higher flows (P < 0.0001). Doppler I catheter slopes were dependent on valve type and size, with more overestimation by Doppler in mechanical (P < 0.01) and larger valves (P < 0.01). Errors due to catheter positioning are more likely wherever effects of pressure recovery are higher: in bioprosthetic valves, smaller valves, and at higher flow rates. Pressure recovery can explain overestimation by Doppler only if localized gradients closer than 1 cm from the valve exist. Clinicians should be aware of these effects of pressure recovery when making major diagnostic and therapeutic decisions.
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Stewart et al. (1994) studied Prosthetic aortic valves. In vitro testing of valve type, size, and flow rate was evaluated on Slope of pressure recovery (gradient with distance from the annulus). In vitro testing of prosthetic aortic valves showed pressure recovery slopes were significantly higher in smaller valves (P<0.01), bioprosthetic valves (P<0.001), and at higher flows (P<0.0001).
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