PubMed · 6021984
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U Williams. 1967-04-28. Aortic valve prothesis.. https://pubmed.ncbi.nlm.nih.gov/6021984/
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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.
BACKGROUND: Noninvasive assessment of functionally stenotic small-diameter aortic mechanical prostheses is complicated by theoretical constraints relating to the hemodynamic relevance of Doppler-derived transprosthetic gradients. To establish the utility of Doppler echocardiography for evaluation of these valves, 20-mm Medtronic Hall and 19-mm St Jude prostheses were studied in vitro and in vivo. METHODS AND RESULTS: Relations between the orifice transprosthetic gradient (equivalent to Doppler), the downstream gradient in the zone of recovered pressure (equivalent to catheter), and fluid mechanical energy losses were examined in vitro. Pressure-flow relations across the 2 prostheses were evaluated by Doppler echocardiography in vivo. For both types of prosthesis in vitro, the orifice was higher than the downstream gradient (P<0.001), and fluid mechanical energy losses were as strongly correlated with orifice as with downstream pressure gradients (r2=0.99 for both). Orifice and downstream gradients were higher and fluid mechanical energy losses were larger for the St Jude than the Medtronic Hall valve (all P<0.001). Whereas estimated effective orifice areas for the 2 valves in vivo were not significantly different, model-independent dynamic analysis of pressure-flow relations revealed higher gradients for the St Jude than the Medtronic Hall valve at a given flow rate (P<0.05). CONCLUSIONS: Even in the presence of significant pressure recovery, the Doppler-derived gradient across small-diameter aortic mechanical prostheses does have hemodynamic relevance insofar as it reflects myocardial energy expenditure. Small differences in function between stenotic aortic mechanical prostheses, undetectable by conventional orifice area estimations, can be identified by dynamic Doppler echocardiographic analysis of pressure-flow relations.
The abnormality most often found at physical examination of the heart is a systolic murmur. Aortic valve stenosis is a feared cause of systolic murmurs, which is also well evaluated with respect to the predictive value of physical diagnostic findings. Auscultatory characteristics of the murmur and palpatory findings of the carotid arteries show an acceptable predictive value and can be used by the general practitioner in the referral or reassurance of individuals with a systolic murmur. The different forms of the systolic murmur can be heard on the Internet address of this journal (http:@appendix.niwi. knaw.nl).