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PubMed2026

Transvalvular Flow Rate is Associated With Mortality Rate and Lifetime Loss in Aortic Valve Stenosis: A Meta-Analysis of Reconstructed Time-to-Event Data.

Low-flow states are associated with adverse outcomes in aortic stenosis (AS), but the prognostic value of transvalvular flow rate (TFR) has not been consistently established across studies. This study is a systematic review and meta-analysis of reconstructed time-to-event data was performed in accordance with Preferred Reporting Items for Systematic Reviews and Meta-analyses. PubMed/MEDLINE, EMBASE, and Cochrane Library were searched for studies (published by November 14, 2025) comparing low versus normal TFR in AS. Data were collected from Kaplan-Meier curves. The primary endpoint was all-cause mortality. Survival was assessed using pooled Kaplan-Meier curves, Cox regression, flexible parametric survival models, and restricted mean survival time (RMST) analysis. A total of 9 studies including 6,494 patients were analyzed; 2,575 (39.7%) had low TFR. At 8 years of follow-up, estimated survival was 34.1% (95% confidence interval [CI] 24.7% to 47%) in the low-TFR group and 63% (95% CI 58.9% to 67.4%) in the normal-TFR group. Low TFR was associated with higher all-cause mortality (hazard ratio 1.59, 95% CI 1.45 to 1.74, p < 0.001). We observed a progressively greater hazard over time, with the hazard ratio approaching 1.9 by 8 years. At 8 years, RMST in the normal-TFR group was 7.37 years (95% CI 7.21 to 7.53 years) versus 5.07 years (95% CI 4.91 to 5.23 years) in the low-TFR group, representing a lifetime loss of 2.3 years in the low-TFR group (ΔRMST -2.30 years, 95% CI -2.53 to -2.07 years, p < 0.001). In patients with AS, low TFR is associated with significantly higher mortality and lifetime loss. These findings support TFR as a clinically meaningful marker for risk stratification in AS.

Aortic Valve Stenosis↗

PubMed1976

Valve dynamics.

Flow between two contiguous elastic sheets (valve leaflets) generates one of two types of behavior. At low pressure differences, e.g. 1 cm H2O, the sheets part slightly and the fluid passes silently between them. The aperture under these silent conditions varies with the square of the length of the orifice, the transvalvular pressure difference and the kinetic energy, divided by the thickness of the leaflets. At higher transvalvular pressure differences the downstream end of the bicuspid valve alternately closes and reopens (flitter), and functions as an acoustic oscillator. The recurrence rate of flitter varies with the tension on the leaflets and inversely with the thickness. The threshold of the onset of flitter varies with the product of the pressure and the square of the length of the valve aperture, divided by the wall tension and thickness. The significance of these data in the onset of the flitter and of the recurrence rate is discussed in terms of the production of sounds and murmurs at the heart valves, vocal cords and other sites.

Acoustics↗

PubMed1978

In vitro hydrodynamic comparison of mitral valve prostheses at high flow rates.

A pulse duplicator system for evaluating the hemodynamic performance of mitral prostheses is described. Under conditions stimulating normal resting physiology, all valves tested had measurable but acceptably small pressure drops. Under conditions simulating exercise, all were moderately to severely stenotic. Valves with nearly equal mounting diameters were compared. The Hancock, Beall, and Starr-Edwards valves (Group A) were found to be significantly more stenotic than the Björk-Shiley, Cutter-Cooley, Ionescu-Shiley, and Lillehei-Kaster valves (Group B). In the 29 to 30 mm. mounting diameter size at cardiac outputs of 5 and 9 L. per minute, Group A had average pressure drops of 3.2 and 10.5 mm. Hg and Group B, pressure drops of 1.6 and 5.3 mm. Hg, respectively. In the 24 to 26 mm. mounting diameter size, at cardiac outputs of 9 L. per minute, all the valves had critically large pressure drops (9 to 17.6 mm. Hg). The standard Gorlin formula is inappropriate for computing the orifice area of prosthetic valves. The discharge coefficient for a valve (a measure of how well the valve uses its primary flow area) and a performance index (a measure of how well the valve uses its mounting area) have been computed from a knowledge of the orifice size, without the necessity of assuming a value for the discharge coefficient required by the Gorlin formula. The biological valves (Hancock and Ionescu-Shiley) provide an efficient orifice for fluid flow at the free leaflet margins and have large discharge coefficients. On the basis of the fluid dynamic equation of motion, steady flow, root mean square (RMS) flow, and peak flow, combined with the appropriate transvalvular gradients, were all shown to yield equally accurate characterizations of valvular hydrodynamic performance. Mean flow, unfortunately the only value obtainable clinically, yielded effective orifice areas 10 percent smaller than either of the other three flow values.

Bioprosthesis↗