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Aortic shear stress in patients with bicuspid aortic valve with stenosis and insufficiency.

ABSTRACT: OBJECTIVES:Bicuspid aortic valve, characterized by valve malformation and risk for aortopathy, displays profound alteration in systolic aortic outflow and wall shear stress distribution. The present study performed 4-dimensional flow magnetic resonance imaging in patients with bicuspid aortic valve with right-left cusp fusion, focusing on the impact of valve function on hemodynamic status within the ascending aorta. METHODS:Four-dimensional flow magnetic resonance imaging was performed in 50 subjects with right-left bicuspid aortic valve and 15 age- and aortic size-matched controls with tricuspid aortic valve. Patients with bicuspid aortic valve were categorized into 3 groups according to their aortic valve function as follows: bicuspid aortic valve with no more than mild aortic valve dysfunction (bicuspid aortic valve control, n = 20), bicuspid aortic valve with severe aortic insufficiency (n = 15), and bicuspid aortic valve with severe aortic stenosis (n = 15). RESULTS:All patients with right-left bicuspid aortic valve exhibited peak wall shear stress at the right-anterior position of the ascending aorta (bicuspid aortic valve vs trileaflet aortic valve at the right-anterior position: 0.91 ± 0.23 N/m2 vs 0.43 ± 0.12 N/m2, P < .001) with no distinct alteration between bicuspid aortic valve with severe aortic insufficiency and bicuspid aortic valve with severe aortic stenosis. The predominance of dilatation involving the tubular ascending aorta (82%, type 2 aortopathy) persisted, with or without valve dysfunction. Compared with bicuspid aortic valve control subjects, the bicuspid aortic valve with severe aortic insufficiency group displayed universally elevated wall shear stress (0.75 ± 0.12 N/m2 vs 0.57 ± 0.09 N/m2, P < .01) in the ascending aorta, which was associated with elevated cardiac stroke volume (P < .05). The bicuspid aortic valve with severe aortic stenosis group showed elevated flow eccentricity in the form of significantly increased standard deviation of circumferential wall shear stress, which correlated with markedly increased peak aortic valve velocity (P < .01). CONCLUSIONS:The location of peak aortic wall shear stress and type of aortopathy remained homogeneous among patients with right-left bicuspid aortic valve irrespective of valve dysfunction. Severe aortic insufficiency or stenosis resulted in further elevated aortic wall shear stress and exaggerated flow eccentricity.

SUBMITTER: Shan Y

PROVIDER: S-EPMC5438758 | biostudies-literature | 2017 Jun

REPOSITORIES: biostudies-literature

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Aortic shear stress in patients with bicuspid aortic valve with stenosis and insufficiency.

Shan Yan Y Li Jun J Wang Yongshi Y Wu Boting B Barker Alex J AJ Markl Michael M Wang Chunsheng C Wang Xiaolin X Shu Xianhong X

The Journal of thoracic and cardiovascular surgery 20170210 6

<h4>Objectives</h4>Bicuspid aortic valve, characterized by valve malformation and risk for aortopathy, displays profound alteration in systolic aortic outflow and wall shear stress distribution. The present study performed 4-dimensional flow magnetic resonance imaging in patients with bicuspid aortic valve with right-left cusp fusion, focusing on the impact of valve function on hemodynamic status within the ascending aorta.<h4>Methods</h4>Four-dimensional flow magnetic resonance imaging was perf ...[more]

PMID: 28268004

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Project description:ImportanceThe outcomes of transcatheter aortic valve replacement (TAVR) in low-risk patients with bicuspid aortic valve stenosis have not been studied in a large scale, multicentered, prospective fashion.ObjectiveTo evaluate the procedural safety, efficacy, and 30-day outcomes of TAVR in patients with bicuspid aortic stenosis at low surgical risk.Design, setting, and participantsThe Low Risk Bicuspid Study is a prospective, single-arm trial study with inclusion/exclusion criteria developed from the Evolut Low Risk Randomized Trial. Follow-up is planned for 10 years. Patients underwent TAVR at 25 centers in the United States who were also participating in the Evolut Low Risk Randomized Trial from December 2018 to October 2019. Eligible patients had severe bicuspid aortic valve stenosis and met American Heart Association/American College of Cardiology guideline indications for aortic valve replacement.InterventionsPatients underwent attempted implant of an Evolut or Evolut PRO transcatheter aortic valve, with valve size based on annular measurements.Main outcomes and measuresThe prespecified primary end point was the incidence of all-cause mortality or disabling stroke at 30 days. The prespecified primary efficacy end point was device success defined as the absence of procedural mortality, the correct position of 1 bioprosthetic heart valve in the proper anatomical location, and the absence of more than mild aortic regurgitation postprocedure.ResultsA total of 150 patients underwent an attempted implant. Baseline characteristics include mean age of 70.3 (5.5) years, 48.0% female (n = 72), and a mean Society of Thoracic Surgeons score of 1.4 (0.6%). Most patients (136; 90.7%) had Sievers type I valve morphology. The incidence of all-cause mortality or disabling stroke was 1.3% (95% CI, 0.3%-5.3%) at 30 days. The device success rate was 95.3% (95% CI, 90.5%-98.1%). At 30 days, the mean (SD) AV gradient was 7.6 (3.7) mm Hg and effective orifice area was 2.3 (0.7) cm2. A new permanent pacemaker was implanted in 22 patients (15.1%). No patients had greater than mild paravalvular leak.Conclusions and relevanceTranscatheter aortic valve replacement in low-surgical risk patients with bicuspid aortic valve stenosis achieved favorable 30-day results, with low rates of death and stroke and high device success rate.Trial registrationClinicalTrials.gov Identifier: NCT03635424.

Project description:OBJECTIVES:The objectives of this study were to investigate an association between the magnitude of flow-mediated aortic wall shear stress (WSS) and medial wall histopathology in patients with bicuspid aortic valve (BAV) with aortopathy. METHODS:Patients with BAV (n = 27; 52 ± 15 years; 3 women; proximal thoracic aorta diameter = 4.4 ± 0.7 and 4.6 ± 0.5 cm) who underwent prophylactic aortic resection received preoperative 3-dimensional time-resolved phase-contrast magnetic resonance imaging with 3-dimensional velocity encoding to quantify WSS relative to a population of healthy age- and sex-matched tricuspid aortic valve control participants (n = 20). Quantitative histopathology was conducted on BAV aorta tissue samples resected at surgery (n = 93), and correlation was performed between elastic fiber thickness and in vivo aortic WSS as continuous variables. Validation of elastic fiber thickness was achieved by correlation relative to tissue stiffness determined using biaxial biomechanical testing (n = 22 samples). RESULTS:Elastic fibers were thinner and WSS was higher along the greater curvature compared with other circumferential regions (vs anterior wall: P = .003 and P = .0001, respectively; lesser curvature: both P = .001). Increased regional WSS was associated with decreased elastic fiber thickness (r = -0.25; P = .02). Patient stratification with subanalysis showed an increase in the correlation between WSS and histopathology with aortic valve stenosis (r = -0.36; P = .002) and smaller aortic diameters (<4.5 cm: r = -0.39; P = .03). Elastic fiber thinning was associated with circumferential stiffness (r = -0.41; P = .06). CONCLUSIONS:For patients with BAV, increased aortic valve-mediated WSS is significantly associated with elastic fiber thinning, particularly with aortic valve stenosis and in earlier stages of aortopathy. Elastic fiber thinning correlates with impaired tissue biomechanics. These novel findings further implicate valve-mediated hemodynamics in the progression of BAV aortopathy.

Project description:BackgroundBicuspid aortic valve (BAV) is common congenital malformation, bicuspid aortic stenosis accounts for a substantial proportion of patients with aortic valve stenosis (AS). Bicuspid AS are more likely to have aortic dilatation with slightly less elliptical annuli, which might lead to paravalvular aortic valve regurgitation (AR) and permanent pacemaker implantation (PPM) after TAVI with higher mortality. Our study aims to understand the therapeutic efficacy and safety of transcatheter aortic valve implantation (TAVI) with a supra-annular structure-based sizing strategy in Chinese AS patients with BAV versus tricuspid aortic valve (TAV).MethodsSeventy-four consecutive tricuspid AS patients and 44 bicuspid AS patients were included and enrolled in the study for analysis. Both groups underwent TAVI performed using balloon sizing less than mild paravalvular AR to assess the proper prosthesis size. The myocardial function within 1 year postoperative were sequentially evaluated using the New York Heart Association (NYHA) class, and echocardiography measurements. The incidence rates of complications at 30 days and 1 year were analyzed. During the 1-year follow-up, the time of death from any cause or complications in both groups was recorded.ResultsThe study found that the percentage of patients with class III-IV of NYHA dropped after TAVI in both groups, and no significant difference between both groups at 1 year. Compared with the tricuspid AS group patients, Bicuspid group patients had more improvement in mean aortic valve gradient from baseline to 1year (-47.47±13.38 vs. -50.22±19.25 mmHg, P<0.05). There were no significant differences in 30-day and one-year compliance outcomes except a lower incidence of AR at post-procedure and 30 days in the tricuspid AS group as the Bicuspid AS group. There were no statistically significant differences in the time of death from any cause or significant complications between groups.ConclusionsTAVI has acceptable therapeutic efficacy and safety and is feasible for AS patients with BAV in China.

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Aortic shear stress in patients with bicuspid aortic valve with stenosis and insufficiency.

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Aortic shear stress in patients with bicuspid aortic valve with stenosis and insufficiency.

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