Flow Characteristics of the SAPIEN Aortic Valve: The Importance of Recognizing In-Stent Flow Acceleration for the Echocardiographic Assessment of Valve Function

Background: Echocardiographic evaluation after transcatheter aortic valve implantation (TAVI) includes estimation of effective orifice area (EOA). EOA calculation depends on sub-valvular stroke volume (SV), which depends on sub-valvular diameter and velocity time integral (VTI). The Medtronic CoreValve area changes throughout its length. We aimed to (i) compare SV at two sites of flow acceleration: ‘pre-stent’ and ‘in-stent, pre-valve’, (ii) assess effects of possible differences in sub-valvular SV on EOA, and (iii) assess agreement of measurement of EOA calculation after CoreValve TAVI. Methods: We studied 43 patients after CoreValve implantation. All had transthoracic echocardiography 5-7 days after TAVI. Sub-valvular SV was measured ‘pre-stent’ and ‘in-stent, pre-valve’. Measurement agreement was assessed by root mean square (RMS) differences and Bland-Altman analyses. Results: SV was consistently higher ‘in-stent, pre-valve’ compared with ‘pre-stent’ (62±20ml vs. 53±19ml, p<0.001), so that EOA was correspondingly larger using ‘in-stent, pre-valve’ measurements (1.7±0.5cm2 vs. 1.4±0.5cm2, p<0.001). Betweenobserver RMS difference for calculation of EOA was higher ‘in-stent, pre-valve’ compared to ‘pre-stent’ (0.53 cm2 vs. 0.23cm2, difference from zero 0.17, p=0.002). Though sub-valvular diameter measurements were variable, VTI variability was additionally higher ‘in-stent, pre-valve’ compared to ‘pre-stent’ (0.42cm vs. 0.6cm, difference from zero -1.74, p=0.11). Conclusion: Calculation of EOA after CoreValve TAVI is highly dependent on sub-valvular sample position. EOA may be underestimated using ‘pre-stent’ SV, and overestimated using ‘in-stent, pre-valve’ SV. Limitations in SV reproducibility suggests EOA should be used in conjunction with other indices of valve function in serial assessment of CoreValve function following TAVI.

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Doppler Echocardiographic Assessment of Prosthetic Aortic Valve Function

CHEST Journal ◽

10.1378/chest.99.2.399 ◽

1991 ◽

Vol 99 (2) ◽

pp. 399-403 ◽

Cited By ~ 2

Author(s):

Toshiji Iwasaka ◽

Charles Z. Naggar ◽

Tetsuro Sugiura ◽

Noritaka Tarumi ◽

Yasuo Takayama ◽

...

Keyword(s):

Aortic Valve ◽

Prosthetic Aortic Valve ◽

Valve Function ◽

Echocardiographic Assessment

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Doppler echocardiographic assessment of prosthetic aortic valve area: Estimation with the continuity equation compared to the Gorlin formula

International Journal of Cardiology ◽

10.1016/s0167-5273(96)02676-9 ◽

1997 ◽

Vol 55 (2) ◽

pp. 177-181

Author(s):

J Mohan

Keyword(s):

Aortic Valve ◽

Continuity Equation ◽

Aortic Valve Area ◽

Area Estimation ◽

Prosthetic Aortic Valve ◽

Echocardiographic Assessment ◽

Valve Area

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The Influence of the Aortic Root Geometry on Flow Characteristics of a Prosthetic Heart Valve

Journal of Biomechanical Engineering ◽

10.1115/1.4029747 ◽

2015 ◽

Vol 137 (5) ◽

Cited By ~ 11

Author(s):

Oleksandr Barannyk ◽

Peter Oshkai

Keyword(s):

Aortic Valve ◽

Heart Valve ◽

Aortic Root ◽

Reynolds Shear Stress ◽

Prosthetic Heart Valve ◽

Flow Characteristics ◽

Aortic Pressure ◽

Valve Prosthesis ◽

Aortic Heart Valve ◽

Valve Diseases

In this paper, performance of aortic heart valve prosthesis in different geometries of the aortic root is investigated experimentally. The objective of this investigation is to establish a set of parameters, which are associated with abnormal flow patterns due to the flow through a prosthetic heart valve implanted in the patients that had certain types of valve diseases prior to the valve replacement. Specific valve diseases were classified into two clinical categories and were correlated with the corresponding changes in aortic root geometry while keeping the aortic base diameter fixed. These categories correspond to aortic valve stenosis and aortic valve insufficiency. The control case that corresponds to the aortic root of a patient without valve disease was used as a reference. Experiments were performed at test conditions corresponding to 70 beats/min, 5.5 L/min target cardiac output, and a mean aortic pressure of 100 mmHg. By varying the aortic root geometry, while keeping the diameter of the orifice constant, it was possible to investigate corresponding changes in the levels of Reynolds shear stress and establish the possibility of platelet activation and, as a result of that, the formation of blood clots.

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