Dysfunction of aortic valve prostheses

Transcription

1 Dysfunction of aortic valve prostheses Kai Andersen Oslo University Hospital Rikshospitalet, Norway

2 Dysfunction of aortic valve prostheses Kai Andersen Oslo University Hospital Rikshospitalet, Norway No conflicts of interest

3 Valve prostheses: Principal types Mechanical prostheses Singleleaflet Bi-leaflet Biologic prostheses Stented Stentless

4 Aortic valve replacement (AVR): Echo imaging Bi-leaflet mechanical prosthesis Stented biologic Short-axis view Long-axis view

5 Assessment of AVR: General aspects Needed clinical information: - type, size and date of AVR - symptoms/ clinical findings, heart rate/ blood pressure - height, weight and body surface area Echocardiographic assessment: - prosthetic valve structure and function - aortic root/ ascending aorta (Ao); morphology and size - left ventricular (LV) size and function Supplementary diagnostics if needed: - fluoroscopy, computer tomography

6 Doppler-derived pressure gradient (ΔP) ΔP = 4 x V 22 ; by the simplified Bernoulli equation (V 2 = jet velocity) Ao ΔP = x (V 22 V 12 ); when LV outflow velocity (V 1 ) >1.5 m/s Pressure recovery, along with energy transformation LO = lateral orifice, CO = central orifice area Overestimation may occur in bi-leaflet prostheses Zoghbi et al. J Am Soc Echocardiogr 2009;22:

7 Doppler-derived measures of AVR function Peak flow velocity Mean gradient Effective orifice area (EOA) Doppler velocity index (DVI); DVI = VTI LVO / VTI JET Acceleration time (AT) Zoghbi et al. J Am Soc Echocardiogr 2009;22: VTI = velocity time integral

8 AVR : Complications Valve thrombosis Bi-leaflet valve thrombosis Pannus in-growth Medtronic Hall prostheses (n=816): 25 years follow-up Valve degeneration; stenosis, regurgitation Paravalvular leakage Endocarditis VT = valve thrombosis TE = thromboembolism Svennevig et al. Circulation 2007; 116:

9 AVR stenosis: Diagnostics Normal function Obstruction; pannus in-growth Peak velocity and mean ΔP; increased PW Doppler LVO 0.9 m/s 0.9 m/s EOA and DVI; reduced Gradually occurred or chronic findings? CW Doppler AVR Leaflet motion, restricted? 2.3 m/s Mean ΔP = 11 mm Hg EOA = 2.0 cm 2 DVI = m/s Mean ΔP = 53 mm Hg EOA = 0.8 cm 2 DVI = 0.18

10 Leaflet motion: Assessment Difficult by echo in the aortic position, particularly as for the closing angle Leaflet motion assessed by TEE Fluoroscopy often necessary TTE = transthoracic echo TEE = transoesophageal echo White = TTE, gray = TEE, dashed gray = fluoroscopy, SDP = single-leaflet, BLP = bi-leaflet Muratori et al. Am J Cardiol 2006;97:94-100

11 Grading of prosthetic aortic stenosis Normal Possible Significant function stenosis stenosis Peak velocity (m/s) <3 3-4 >4 Mean ΔP (mm Hg) < >35 EOA (cm 2 ) > <0.8 DVI <0.25 AT (ms) < >100 Adapted from: Zoghbi et al. J Am Soc Echocardiogr 2009;22:

12 Causes of obstruction: Valve thrombosis PW Doppler LVO CW Doppler AVR 0.9 m/s 4.7 m/s Mean ΔP 58 mm Hg, EOA 0.6 cm 2, DVI 0.22 Fluoroscopy; asymmetric/ restricted leaflet motion

13 Pannus in-growth: Concomitant thrombosis may occur Subvalvular pannus possibly, adherent mobile thrombus as well? Though - leaflet motion apparently normal

14 Degenerated biologic valves Moderately stenotic stented valve mean ΔP 33 mm Hg, EOA 1.0 cm 2 Regurgitation (top) in severely degenerated valve (bottom)

15 AVR: Regurgitation Normal; minor, physiologic leaks in mechanical valves Abnormal; - central (mostly in biologic) - paravalvular Physiologic leak in bi-leaflet valve Localization; may need TEE Quantitation; as in native valves TTE long-axis view

16 Grading of prosthetic aortic regurgitation Mild Moderate Severe Valve structure/ motion Normal Abnormal Abnormal Jet width (% LVO diam.) <25% 26 64% 65% Jet density (CW Doppler) Faint Dense Dense Pressure half time (ms) > <200 Flow reversal desc. Ao Brief Intermediate Holodiast. Adapted from: Zoghbi et al. J Am Soc Echocardiogr 2009;22:

17 Paravalvular regurgitation Severe regurgitation jet width >65% of LVO diameter Paravalvular - predominantly located in non-coronary sinus

18 AVR: Endocarditis Vegetation Paravalv. abscess Valve dehiscense Paravalv. leakage Haemodynamics; diast. MR suggesting severely increased LV EDP MR = mitral regurgitation, EDP = end-diastolic pressure

19 Dysfunction of aortic valve prostheses: Summary Echo/ Doppler; modality of choice for assessment after AVR Doppler modalities essential, also due to possible limitations of imaging alone, as particularly in mechanical valves In suspected AVR dysfunction, TEE frequently needed The assessment often more challenging than of native valves; importantly findings should be taken in clinical context High gradients not necessarily due to prosthetic dysfunction Serial comparison with postoperative findings is essential