Quantification of pressure gradients across stenotic valves by Doppler ultrasound

Stamm, R. Brad; Martin, Randolph P.

doi:10.1016/s0735-1097(83)80311-8

Cited by 272 publications

(62 citation statements)

References 22 publications

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“…the Bernoulli equation) for selected 0.5, 1.0, and 1.5 cm2 tunnels. For all three cross-sectional areas studied, results for the 4 figure 5, bottom, the slope of the relationship was significantly greater than 1 for the regression equation with measured gradient on the abscissa and Doppler gradient on the ordinate (i.e., Doppler gradient = 1.58 x measured gradient + 4.5 mm Hg), suggesting 662 that the Doppler method significantly overestimated the measured interventricular gradients.…”

Section: Resultsmentioning

confidence: 86%

Continuous-wave Doppler velocities and gradients across fixed tunnel obstructions: studies in vitro and in vivo.

Yoganathan¹,

Valdes-Cruz²,

Schmidt-Dohna³

et al. 1987

Circulation

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The simplified Bernoulli relationship appears to be quite accurate for predicting gradients across discrete valvular obstructions. Controversy exists about how accurately it predicts the severity of disease in longer segment obstructions. In this study we constructed a pulsatile model of subvalvular pulmonary stensosis in vitro to study nine custom-made subvalvular tunnels 2, 4, and 7 mm in length with flow cross sections of 0.5 to 1.5 cm2 and with the stenotic segment proximal to a nonstenotic bioprosthetic valve, and a pulsatile model in vitro of a 16 mm long tunnel-like ventricular septal defect (VSD) of varying cross-sectional area (0.20 to 0.64 cm2). We also compared the observations in vitro with those in an open-chest dog preparation with a tunnel-like interventricular communication. In the subpulmonic stenosis model, for each individual tunnel, 10 instantaneous peak gradients between 15 to 105 mm Hg were available. The pressure gradients across the tunnel alone, measured in the subvalvular area, were consistently higher than the measured gradients across the tunnel plus valve, suggesting some relaminarization of flow (i.e., a decrease in velocity) and pressure recovery (i.e., an increase in pressure) distal to the obstruction. Continuous-wave Doppler velocities across the 4 and 7 mm tunnels for the highest gradients were slightly lower than for the 2 mm tunnel at the same gradients, and it was only for the 0.5 cm2 cross section, 4 and 7 mm tunnels that there was a suggestion of minor viscous energy loss. For all the subvalvular tunnels studied, the Bernoulli relationship accurately predicted the results of the pressure drop across the tunnel only, while the gradient across tunnel plus valve was consistently lower. For the VSD tunnel model in vitro, the Doppler-derived gradients were approximately 40% higher than the measured gradients. The findings for the subvalvular and VSD tunnels in vitro and similar findings in the open-chest dogs with VSD suggest that relaminarization of flow and recovery of pressure occurred distal to the tunnel orifice, whereas continous-wave Doppler findings correlate with the highest instantaneous gradients measured in the lowest pressure areas at the vena contracta of the tunnel.

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Section: Resultsmentioning

confidence: 86%

Continuous-wave Doppler velocities and gradients across fixed tunnel obstructions: studies in vitro and in vivo.

Yoganathan¹,

Valdes-Cruz²,

Schmidt-Dohna³

et al. 1987

Circulation

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“…The accuracy and validity of the ultrasonographic approach, in aortic stenosis quantification, have been confirmed in numerous laboratories. 12,13 The effective orifice area (EOA) on the aortic valve was calculated as follows…”

Section: Echocardiographic Evaluationmentioning

confidence: 99%

Arterial Remodeling of the Common Carotid Artery After Aortic Valve Replacement in Patients With Aortic Stenosis

Irace

Gnasso

Cirillo

et al. 2002

Stroke

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Background and Purpose-Aortic stenosis, causing flow abnormalities, disturbs the normal hemodynamics in the common carotid arteries. The aim of the present study was to investigate the remodeling process of the common carotid arteries after surgical correction of aortic stenosis. Methods-Eleven subjects with aortic stenosis were studied before and 1 and 6 months after aortic valve replacement.Arterial diameter, intima-media thickness (IMT), and flow velocity were measured by echo-Doppler examination. Shear stress, blood flow, and pulsatility index were calculated. Blood viscosity and hematocrit were measured by standard methods. A control group was also enrolled. Results-Before surgery, compared with controls, patients had lower systolic peak velocity but higher mean and end-diastolic velocity. Arterial diameter, IMT, and blood flow were comparable in the 2 groups. Blood viscosity, hematocrit, wall shear stress, and pulsatility index were markedly lower in patients. After surgery, IMT was reduced (0.741Ϯ0.152 versus 0.627Ϯ0.108 mm before and 6 months after surgery, respectively; PϽ0.0001), and hematocrit and blood viscosity increased, leading to increased wall shear stress (mean wall shear stress, 7.83Ϯ1.97 versus 9.65Ϯ3.12 dyne/cm 2 before and 6 months after surgery, respectively; PϽ0.02). Conclusions-The present results demonstrate that aortic valve replacement, in subjects with aortic stenosis, leads to reduction of the common carotid artery IMT. Wall shear stress is increased after the intervention and probably mediates the remodeling process.

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“…Some may argue that Doppler gradients may be a little higher than catheterization gradients and a higher Doppler gradient should have been chosen (70 and above) when considering aortic valve replacement. However, transvalvular aortic pressure gradient measured by Doppler is as accurate as the catheterization gradient [10][11][12][13]. All 11 patients who had an aortic pressure gradient between 50 and 70 and heart failure died within 1-33 months (with a mean of 16 months) from the time of echocardiographic diagnosis.…”

Section: Discussionmentioning

confidence: 99%

Why do so few older people with aortic stenosis have valve replacement surgery?

Abdul-Hamid

Mulley²

1999

Age and Ageing

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Background: many older patients with severe aortic stenosis do not have valve replacement surgery. Objective: to determine the proportion of older people with symptomatic aortic stenosis referred for specialist assessment and the reasons for non-referral. Methods: retrospective study of all patients over 75 attending the geriatric department of an English teaching hospital. Confirmation was by reviewing all echocardiographic reports. Results: of 40 patients with symptomatic aortic stenosis, only four had undergone surgery. Seven patients refused operation; five were medically unfit (for reasons other than heart failure) and reasons for not referring could not be found in 13 casenotes. Of the 15 patients referred to a cardiologist, eight were considered suitable for surgery. Conclusion: only one in five patients over 75 with echocardiographically-confirmed aortic stenosis was considered for surgery. Prospective studies are needed to determine why patients and geriatricians do not seek specialist assessment for this treatable condition.

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Quantification of pressure gradients across stenotic valves by Doppler ultrasound

Cited by 272 publications

References 22 publications

Continuous-wave Doppler velocities and gradients across fixed tunnel obstructions: studies in vitro and in vivo.

Continuous-wave Doppler velocities and gradients across fixed tunnel obstructions: studies in vitro and in vivo.

Arterial Remodeling of the Common Carotid Artery After Aortic Valve Replacement in Patients With Aortic Stenosis

Why do so few older people with aortic stenosis have valve replacement surgery?

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