Echocardiographic Assessment of Heart Valve Prostheses.

Patients submitted to valve replacement with mechanical or biological prosthesis, may present symptoms related either to valvular malfunction or ventricular dysfunction from other causes. Because a clinical examination is not sufficient to evaluate a prosthetic valve, several diagnostic methods have been proposed to assess the functional status of a prosthetic valve. This review provides an overview of echocardiographic and Doppler techniques useful in evaluation of prosthetic heart valves. Compared to native valves, echocardiographic evaluation of prosthetic valves is certainly more complex, both for the examination and the interpretation. Echocardiography also allows discriminating between intra- and/or peri-prosthetic regurgitation, present in the majority of mechanical valves. Transthoracic echocardiography (TTE) requires different angles of the probe with unconventional views. Transesophageal echocardiography (TEE) is the method of choice in presence of technical difficulties. Three-dimensional (3D)-TEE seems to be superior to 2D-TEE, especially in the assessment of paravalvular leak regurgitation (PVL) that it provides improved localization and analysis of the PVL size and shape.

INTRODUCTION

Prosthetic heart valves have been successfully used in heart valve replacement over the past 40 years and can be classified into three categories: Mechanical, biologic, and transcatheter valves [Figure 1]. Despite numerous advances have been made for the development of better prostheses, remain several problems related to their use as thrombosis, thromboembolism, hemolysis, tissue overgrowth, regurgitation, and damage to endothelial lining.[1]

Figure 1

Different types of prosthetic valves. (a) Bileaflet mechanical valve (St Jude); (b) monoleaflet mechanical valve (Medtronic Hall); (c) caged ball valve (Starr-Edwards); (d) stented porcine bioprosthesis (Medtronic Mosaic); (e) stented pericardial bioprosthesis (Carpentier- Edwards Magna); (f) stentless porcine bioprosthesis (Medtronic Freestyle); (g) percutaneous bioprosthesis expanded over a balloon (Edwards-Sapien); and (h) self-expandable percutaneous bioprosthesis (Core Valve)

MECHANICAL VALVES

The three classes ofmechanical valves aretilting disk, bileaflet, and ball-and-cage which differ primarily in the type and function ofocclude [Figure 1a–c]. Tilting disk or monoleaflet valves consist of a circular occluder disk which typically opens to 60-80° resulting in two distinct orifices of different sizes. Bileaflet valves are made of two semilunar disks attached to a rigid valve ring by small hinges and are the most common valve. The opening angle of the leaflets relative to the annulus plane ranges from 75° to 90°, and the open valve consists of three orifices: A small, slit-like central orifice between the two open leaflets and two larger semicircular orifices laterally. Caged-ball valves are no longer implanted and consist of a silastic ball with a circular sewing ring and a cage formed by three metal arches.[2]

BIOLOGIC VALVES

Biologic valves are classified into three categories: Stented, unstented, and homograft valves [Figure 1d–f]. These valves are manufactured from biologic tissues which is less thrombogenic thanmechanical valves and do not require anticoagulation treatment. Bioprosthesis share the characteristics of flexible leaflets, a single orifice, and no leakage after valve closure; but suffer more easily from calcification. Stented bioprosthesis consists of three biologic leaflets made from the porcine aortic valve or bovine pericardium, mounted on a metal or polymeric stented ring. Unstented bioprosthesis are manufactured from porcine, bovine, or equine tissue and do not have rigid stents. Homograftsare cryopreserved human valves.[12]

TRANSCATHETERVALVES

Transcatheter valves are essentially bioprosthetic valve mounted in aortic and pulmonary position [Figure 1g and h]. In particular, percutaneous aortic valve implantation is an alternative to standard aortic valve replacement in patients with symptomatic aortic stenosis at high operative risk.[3456] The valves are usually implanted using a percutaneous transfemoral approach or a transapical approach througha small thoracotomy.[7]

DOPPLER-ECHOCARDIOGRAPHIC EVALUATION OF PROSTHETIC VALVES

Baseline assessment

Doppler echocardiography is the method of choice to evaluate prosthetic valve function and follows the same principles used for the evaluation of the native valves. A completeechocardiography includes two-dimensional (2D) imaging of the prosthetic valve, evaluation of valve leaflet/occlude morphology and mobility, measurement ofthe transprosthetic gradients and effective valvar orifice area (EOA), estimation of the degree of regurgitation, evaluation ofleft ventricle left ventricle (LV) size and systolic function, and calculation of systolic pulmonary arterial pressure.[12] Before echocardiography, evaluation is extremely important to know some clinical data as:

The type and size of the replacement valve

The date of surgery

Blood pressure and heart rate

The patient's height, weight, and body surface area (BSA) to identify a possible patient prosthesis mismatch (PPM).

EVALUATION OF PROSTHETIC VALVE STENOSIS

Qualitative parameters

In the recognition of prosthetic valve stenosis, first it is extremely important to evaluate valve leaflet/occlude morphology and mobility. Generally, the leaflets oftissue valve appear thin with no evidence of prolapsed and unrestricted motion [Figure 2]. Stentless, homograft, or autograft valves may be indistinguishable from native valves. However, transesophageal echocardiography (TEE) allows a more detailed assessment about cusps calcification, endocarditis vegetations, thrombus, pannus, and reduced disk/ball/leaflet mobility. Prosthetic valve stenosis is generally associated with an abnormal valve morphology and mobility. In the case of mechanical valves there is a reduced or absent occluder mobility. For example, direct signs of prosthetic valve thrombosis include immobility or reduced leaflet mobility, and the presence of thrombus on either side of the prosthesis. Instead, pannus ingrowth appears as a progressive obstruction due to a subvalvular annulus.[891011] Biologic valves stenosis areoften associated with calcification, thickening, and reduced mobility of the leaflets [Figure 3].

Figure 2

Example of normal aortic biologic valve in systole as seen by TEE. TEE = Transesophageal echocardiography

Figure 3

Marked calcification of mitral biologic valve

Quantitative parameters

Quantitative parameters of prosthetic valve function include:

Transprosthetic velocity and pressure gradient;

Transprosthetic jet contour and acceleration time;

Doppler velocity index (DVI);

EOA.

Transprosthetic velocity and gradient

The flow velocity through a prosthetic valve is carried out with the Doppler as a native valve and includes pulsed-wave (PW) and continuous wave (CW) and color Doppler. Measurements of the prosthetic velocity and gradients must be performed by several windowsin order to minimize angulation between the Doppler beam and flow direction and to obtain the highest velocity.[101112] However, the fluid dynamics of the mechanical valves may differ from those of the native valve. Generally, the flow is eccentric in monoleaflet valves and composed of three jets in bileaflet valves [Figure 4]. Sometimes, an abnormally high jet gradient may be detected by CW Doppler through the smaller central orifice ofbileaflet mechanical aortic or mitral prostheses leading to an overestimation of gradient. Pressure gradient is calculated with the use of the simplified Bernoulli equation: AP = 4 × VPr2, where VPr is the velocity of the peak transprosthetic flow jet in meters per second. Prosthetic valve stenosis is generally associated with increased transprosthetic peak flow velocity or mean gradient (at least 3 m/s or 20 mmHg for aortic prostheses and at least 1.9 m/s or 6 mmHg for mitral prostheses) [Tables 1 and 2, Figures 5 and 6].

Figure 4

Example of bileaflet mechanical valve

Table 1

Doppler parameters of prostethic aortic valve (PrAV) function

Parameter	Normal	Possible stenosis	Significant stenosis
Peak velocity (m/s)	<3	3-4	>4
Mean gradient (mmHg)	<20	20-35	>35
DVI	>0.30	0.29-0.25	>0.25
EOA (cm2)	>1.2	1.2-0.8	>0.8
Contour of the jet velocity through the PrAV	Triangular, early peaking	Triangular to intermediate	Rounded, symmetrical contour
AT (ms)	<80	80-100	>100

Adapted from Zoghbi et al. Recommendations for evaluation of prosthetic valves with echocardiography and Doppler ultrasound: A report from the American society of echocardiography’s guidelines and standards committee and the task force on prosthetic valves. J Am Soc Echocardiogr 2009. DVI = Doppler velocity index, EOA = Effective valvar orifice area

Table 2

Doppler parameters of prosthetic (Pr) mitral valve function

Parameter	Normal	Possible stenosis	Significant stenosis
Peak velocity (m/s)	<1.9	1.9-2.5	>2.5
Mean gradient (mmHg)	<5	6-10	>10
VTIPr/VTILVOT	<2.2	2.2-2.5	>2.5
EOA (cm2)	>2	1-2	>1
PHT (m/s)	<130	130-200	>200

Adapted from Zoghbi et al. Recommendations for evaluation of prosthetic valves with echocardiography and Doppler ultrasound: A report from the American society of echocardiography’s guidelines and standards committee and the task force on prosthetic valves. J Am Soc Echocardiogr 2009. VTI = Velocity time integral, LVOT = Left ventricular outflow tract, EOA = Effective valvar orifice area, PHT = Pulmonary hypertension

Figure 5

Mechanical aortic prostheses. High transprosthetic peak flow velocity and mean gradient

Figure 6

Mitral bioprostheses. High transprosthetic peak flow velocity and mean gradient

Transprosthetic jet contour and acceleration time

The contour of the velocity through the prosthesis can be used to evaluate prosthetic aortic valve function. Generally, in a normal valve, the contourof the CW flow velocity has a triangular shape with early peaking of the velocity and short acceleration time (time from the onset of flow to maximal velocity <80 ms). Inprosthetic valve stenosis, is observed a more rounded velocity contour with the velocity peaking in mid-ejection, prolonged acceleration time, and ejection time as well as the ratio of acceleration time to ejection time (greater than 0.4).[10111213]

DVI

The DVI is the ratio between the velocity time integral (VTI) of the left ventricular outflow tract (LVOT) flow and the VTI of the transprosthetic flow: DVI = VTILVOT/VTIPrAV. In the case of prosthetic mitral valve is calculated by dividing the VTI of the transprosthetic flow by that of the LVOT flow: DVI = VTIPrMv /VTILVOT. The DVI is reduced (less than or equal to 0.3) in case of prosthetic aortic valve stenosis, while is increased (greater than or equal to 2.2 m/s) in case of prosthetic mitral valve stenosis.[13]

EOA

The EOA ofprosthetic aortic valves is calculated with the continuity equation: EOA= (CSALVOT ΄ VTILVOT)/VTIPrAV. CSALVOT is the cross-sectional area of the LVOT, VTILVOT the velocity-time integral obtained by PW Doppler in the LVOT, VTIPrAV the velocity-time integral obtained by CW Doppler through the aortic prosthesis. The cross-sectional area of the LVOT is obtained from diameter measurement just close the prosthesis from the parasternal long-axis view. For the assessment of LVOT velocity signal, it is important to locate the PW Doppler sample volume adjacent to the prosthesis. The VTI across the prosthesis is obtained from the same signals, used for measurement ofprosthesis peak velocity and gradient [Figure 7].[141516] The EOA ofprosthetic mitral valves is calculated as EOA = (CSALVOT ΄ VTILVOT)/VTIPrMV, where VTIPrMV is thevelocity-time integral obtained by CW Doppler through the mitral prostheses.[17] The EOAis the most validated parameter for identifying the PPM.

Figure 7

Calculation of the effective valvar orifice area (EOA) of prosthetic aortic valve with the continuity equation

PPM

PPM occurs when the EOA of a normally functioning prosthesis is too small in relation to the patient's body size resulting in abnormally high postoperative gradients. Valve EOAs between 0.8 and 1.2 cm2 and between 1.0 and 2.0 cm2 suggest the presence of possible stenosis for aortic and mitral prostheses, respectively; whereas, values less than 0.8 cm2 (aortic) and less than 1.0 cm2 (mitral) indicate the presence of significant stenosis.[19] However, the recognition of prosthetic valve stenosis is better achieved by comparing the measuredEOA to the normal reference value ofEOA for the model and size of prosthesis implanted in the patient.[18192023242526] Tables 3 and 4 shows the normal reference values of EOAs for the aortic and mitral prostheses. The most widely accepted parameter for identifying PPM is the indexed EOA, that is, the EOA of the prosthesis divided by the patient's BSA. A value of EOA <0.6 cm2/m2 in aortic position and 0.9 cm2/m2 in mitral position identify a sever PPM.[212223]

Table 3

Normal reference values of EOAs for the main aortic prostheses

Aortic prosthetic valve Size (mm)

19 21 23 25 27 29

Main stented bioprosthesis

Mosaic 1.1±0.2 1.2±0.3 1.4±0.3 1.7±0.4 1.8±0.4 2.0±0.4

Hancock II 1.2±0.1 1.3±0.2 1.5±0.2 1.6±0.2 1.6±0.2

Carpentier-Edwards Perimount 1.1±0.3 1.3±0.4 1.5±0.4 1.8±0.4 2.1±0.4 2.2±0.4

Carpentier-Edwards Magna 1.3±0.3 1.7±0.3 2.1±0.4 2.3±0.5

Aorticstentless bioprosthesis

Medtronic Freestyle 1.2±0.2 1.4±0.2 1.5±0.3 2.0±0.4 2.3±0.5

St Jude Medical Toronto SPV.1.3±0.3 1.5±0.5 1.7±0.8 2.1±0.7 2.7±1.0

Main aortic mechanical bioprosyehesis

Medtronic Hall 1.2±0.2 1.3±0.2

Medtronic Advantage 1.7±0.2 2.2±0.3 2.8±0.6 3.3±0.7 3.9±0.7

St Jude Medical Standard 1.0±0.2 1.4±0.2 1.5±0.5 2.1±0.4 2.7±0.6 3.2±0.3

Carbomedics Standard 1.0±0.4 1.5±0.3 1.7±0.3 2.0±0.4 2.5±0.4 2.6±0.4

Adapted from Pibarot P et al. Prosthetic Heart Valves: Selection of the Optimal Prosthesis and Long-Term Management. Circulation 2009). EOA = Effective valvar orifice area

Table 4

Normal reference values of EOAs for the mitral prostheses

Mitral prostetic valve Size (mm)

25 27 29 31 33

Main stented bioprosthesis

Medtronic Mosaic 1.5±0.4 1.7±0.5 1.9±0.5 1.9±0.5

Hancock II 1.5±0.4 1.8±0.5 1.9±0.5 2.6±0.5 2.6±0.7

Carpentier-Edwards Perimount 1.6±0.4 1.8±0.4 2.1±0.5

Mechanical bioprosthesis

St Jude Medical Standard 1.5±0.3 1.7±0.4 1.8±0.4 2.0±0.52.0±0.5

MCRIOn-X 2.2±0.9 2.2±0.9 2.2±0.9 2.2±0.9 2.2±0.9

Adapted fromPibarot et al. Prosthetic Heart Valves: Selection of the Optimal Prosthesis and Long-Term Management. Circulation 2009. EOA = Effective valvar orifice area, MCRI = Medical Carbon Research Institute

OTHER CAUSES OFHIGH TRANSPROSTHETIC GRADIENTS

PPM is the principle cause of high gradient after valve replacement, but should be considered other causes of elevated transprosthetic gradient as: Intrinsic valve dysfunction, high flow state, technical errors, and central jet artifact in bileaflet valve. However, in the case of prosthetic aortic valve, to better appreciate the clinical impact of an elevated gradient, it also should considered that the net gradient is less in patients with a small aortic diameter (<3cm) because of pressure recovery and it is useful to calculate the energy loss index.[19343536373841] So in patients with small aortait could be possible an overestimate ofprosthesis valve stenosis [Figure 7].[272829]

EVALUATION OF PROSTHETIC VALVE REGURGITATION

In the assessment ofprosthesis regurgitation is extremely important to distinguish physiologic from pathologic regurgitation. First, we must remember that mechanical prostheses have a normal regurgitant volume known as “leakage backflow”. This “built-in” regurgitation theoretically prevents blood stasis and thrombus formation using a washing effect. Otherwise the pathologic regurgitant jets, the normal leakage backflow jets are characterized by being short in duration, narrow, and symmetric.[240]

Prosthetic aortic valve regurgitation

General considerations

Transthoracic echocardiography (TTE) generally provides a good visualization of both transvalvular and paravalvular aortic regurgitation.[3341] However, regurgitant jets may be occulted by acoustic shadowing, especially in the noncoronary sinus region. When TTE is technically difficult, TEE may be useful to identify the origin and the mechanism of the regurgitant jets and to identify possible complications, such as flail bioprosthetic cusp, presence of pannus, thrombus, vegetations, abscess formation, or prosthesis dehiscence [Figures 8 and 9].[303132]

Figure 8

Thrombosis of mechanical mitral prosthesis as seen by TEE

Figure 9

Dehiscence of mechanical mitral prosthesis as seen by TEE

Parameters of the severity of prosthetic aortic valve regurgitation

The estimation of the severity of prosthetic aortic valve regurgitation can be performed similarly to native valve regurgitation.[40] However, there are limited data on the application and validation of quantitative parameters such as the width of the regurgitant jet or of the vena contracta, the effective regurgitant orifice area, and the regurgitant volume in the context of prosthetic valves. For this reasonis necessarya multiparametric approach [Table 5].

Table 5

Parameters for evaluation of the severity of prosthetic aortic valve regurgitation

Parameter	Mild	Moderate	Severe
Valve structure and motion
Mechanical or bioprosthetic	Usually normal	Abnormal	Abnormal
Structural parameters
LV size	Normal	Normal or mildly dilated	Dilated
Doppler parameters
Jet width in central jets (% LVO diameter): Color	Narrow (≤ 25%)	Intermediate (26-64%)	Large (≥65%)
Jet density: CW Doppler	Incomplete or faint	Dense	Dense
Jet deceleration rate (PHT, ms): CW Doppler	Slow (>500)	Variable (200-500)	Steep (<200)
LVO flow vs pulmonary flow: PW Doppler	Slightly increased	Intermediate	Greatly increased
Diastolic flow reversal in the descending aorta: PW Doppler	Absent or brief early diastolic	Intermediate	Prominent, holodiastolic
Doppler parameters (quantitative)
Regurgitant volume (mL/beat)	<30	30-59	>60
Regurgitant fraction (%)	<30	30-50	>50

Adapted from Zoghbi et al. Recommendations for evaluation of prosthetic valves with echocardiography and Doppler ultrasound: A report from the American Society of Echocardiography’s Guidelines and standards committee and the task force on prosthetic valves. J Am Soc Echocardiogr 2009. LVO = Left ventricular outflow, CW = Continuous wave, PHT = Pulmonary hypertension, PW = Pulse wave

Color Doppler parameters

The ratios of regurgitant jet diameter to LVOT diameter from the parasternal long-axis view and of jet area to LVOT area from the parasternal short-axis view just below the prosthesis can be used to estimate the severity of central regurgitation. A ratio of jet diameter to LVOT diameter greater than 25% suggests moderate regurgitation and > 65% severe regurgitation. However, using this approach, regurgitation severity may be overestimated in the case of eccentric jets and underestimated in the case of jets impinging the wall of the LVOT or of anterior mitral valve. Unlike the native valves, is difficult, in the long-axis view, to measure the vena contracta width because of the shadowing caused by the prosthesis ring or stent. For semiquantitative evaluation of the severity of paravalvular regurgitation, careful imaging of the neck of the jet in a short-axis view, at the level of the prosthesis sewing ring or stent, allows determination of the circumferential extent of paravalvular regurgitation. A regurgitant jet occupying less than 10% of the sewing ring or stent circumference suggests mild, 10-20% suggests moderate, and more than 20% suggests severe regurgitation. Rocking of the prosthesis is usually associated with greater than 40% dehiscence.[414243] Moreover, the estimation of regurgitation severity becomes complex in the case ofmultiple jets so TEE may be helpful to better identify the origin of the regurgitant leak and to better estimate its circumferential extension [Figure 10].

Figure 10

Paravalvular aortic leak

Spectral Doppler parameters

Spectral Doppler parameters are useful to assess prosthetic aortic valve regurgitation because they are less sensitive to the prosthesis position, shadowing, and artifacts. The pressure half-time of the CW regurgitant jet signal is useful when the value is less than 200 ms, suggesting severe regurgitation, or greater than 500 ms, suggesting mild regurgitation. Moderate AR is associated with the presence of holodiastolic flow reversal in the descending thoracic aorta; severe AR is suspected when the VTI of the reverse flow approximates that of the forward flow and when the end-diastolic velocity is greater than 18 cm/s.[40]

Prosthetic mitral valve regurgitation

Evaluation of prosthetic mitral regurgitation by TTE is problematic because the left atrium (LA) is largely occulted by the acoustic shadowing due to the metallic components of the prosthesis. In contrast, TEE provides excellent visualization of the LA and mitral regurgitant jet, but acoustic shadowing limits visualization of the LV.[40] At TTE, the presence of “occult” mitral prosthesis regurgitation should be suspected in the presence of some signs as: Flow convergence on the LV side of the prosthesis during systole, increased mitral peak E wave velocity (greater than 2 m/s), mean gradient greater than 6 mmHg, DVI greater than 2.2, unexplained or new worsening of pulmonary arterial hypertension, and a dilated and hyperkinetic LV.[33] In the suspicion of pathologic mitral regurgitation, it is imperative to perform a TEE study. On color Doppler, paravalvular leaks have a typical appearance of a jet that passes from the LV into the LA outside the prosthesis ring and often projects into the atrium in an eccentric direction [Figure 11].

Figure 11

Color Doppler images of severe paravalvular mitral regurgitation

Parameters of the severity of prosthetic mitral valve regurgitation

Assessment of severity of prosthetic mitral regurgitation is complex so it is recommended a multiparametricapproach [Table 6]. The estimation of regurgitant jet area in the LA is often difficult due to the shadowing and artifacts created by the prosthesis. However, a small thin jet (jet area less than 4 cm2, less than 20% of the LA) usually reflects mild mitral regurgitation; whereas, a large, wide jet (8 cm2 or larger, more than 40% of the LA) is often associated with severe regurgitation. A width of the vena contracta of less than 3, 3-6, and greater than 6 mm denotes mild, moderate, and severe regurgitation, respectively. Severemitral regurgitation is generally associated with swirling of the jet within the atrium and with retrograde systolic flow in the pulmonary veins that can be more accurately evaluated by TEE. Finally, also the density and contour of the regurgitant jet CW Doppler signal may be helpful to corroborate regurgitation severity [Figure 12]. Because mitral prosthetic regurgitation is often characterized by eccentric and/or multiple jets, the proximal isovelocity surface area method is difficult to achieve and may under- or overestimate regurgitation severity. For these reasons, the volumetric method is often preferred to the proximal isovelocity surface area method for quantitation of mitral prosthesis regurgitation.[39404144]

Table 6

Echocardiographic and Doppler criteria for severity of prosthetic MR

Parameter	Mild	Moderate	Severe
Structural parameters
LV size	Normal	Normal or dilated	Usually dilated
Prosthetic valve	Usually normal	Abnormal	Abnormal
Doppler parameters
Color flow jet area	Small, central jet (usually <4 cm2 or <20% of LA area)	Variable	Large central jet (usually >8 cm2 or >40% of LA area) or variable size wall-impinging jet swirling in left atrium
Flow convergence	None or minimal	Intermediate	Large
Jet density: CW Doppler	Incomplete or faint	Dense	Dense
Jet contour: CW Doppler	Parabolic	Usually parabolic	Early peaking, triangular
Pulmonary venous flow	Systolic dominance§	Systolic blunting§	Systolic flow reversal†
Quantitative parameters††
VC width (cm)	<0.3	0.3-0.59	≥0.6
R vol (mL/beat)	<30	30-59	≥60
RF (%)	<30	30-49	≥50
EROA (cm2)	<0.20	0.20-0.49	≥0.50

Adapted from Zoghbi et al. Recommendations for evaluation of prosthetic valves with echocardiography and Doppler ultrasound: A report from the American society of echocardiography’s guidelines and standards committee and the task force on prosthetic valves. J Am Soc Echocardiogr 2009. MR = Mitral regurgitation, LV = Left ventricle, LA = Left atrium, CW = Continuous wave, VC = Vena contracta, R = Regurgitant, RF = regurgitant fraction, EROA = Effective regurgitant orifice area

Figure 12

CW Doppler signal of severe paravalvular mitral regurgitation CW = Continuous wave

SPECIFIC CONSIDERATIONS FOR PARTICULAR VALVE

Prosthetic pulmonary valve

Prosthetic pulmonary valve are, generally, implanted in pediatric patients with congenital heart disease. Clues suspicion of prosthetic stenosis are marked thickening or immobility of the cusps, a small map to color Doppler, transvalvular peak velocity greater than 3 m/s, or 2 m/s, respectively for prosthesis and homograft, the presence of a depressed right ventricular functionor elevated right ventricular systolic pressure. In the presence of a severe pulmonary insufficiency, instead, there is a right ventricle volume overload associated with diastolic flattening and paradoxical movement of the interventricular septum.[121340]

Prosthetic tricuspid valve

A suspicion of prosthetic tricuspid stenosis is given by the presence of an abnormal morphology and mobility of the leaflet, a transvalvular peak velocity greater than 1.7 m/sec, amean gradient equal or greater than 6 mmHg and a pressure half -time at least 230 msec.[1340]

Transcathether aortic valve

Two devices are most commonly used for transcathether aortic valve implantation. One device is the EdwardsS APIEN valve which consists of three pericardial leaflets, mounted within aballoon-expandable stent. The other device is the CoreValve ReValving system which has three pericardial leaflets mounted in a self-expanding, nitinol frame. The main approaches are transfemoral and transapical.[44] Aortic regurgitation is considered the most common drawback of transcatheter valves.[454647] Traditionally, it is categorized as transvalvular, paravalvular, or combined [Figure 13]. A third form of regurgitation termed supraskirtal has recently been described.[4950515253]

Figure 13

Regurgitation mechanisms after transcatheter aortic valve implantation (a) Transvalvular regurgitation (arrow) (b) paravalvular (arrow); (c) supraskirtal regurgitation above the skirt (arrow)

Adapted from Stähli et al. Aortic regurgitation after transcatheter aortic valve implantation: Mechanisms and implications. Cardiovasc Diagn Ther 2013;3:15-22.

Paravalvular AR is the result of incomplete apposition of the prosthesis to the aortic annulus [Figures 13b and 14b]. Transvalvular AR is the result of restricted leaflet motion, leaflet destruction, and incorrect sizing or overdilatation of the valve [Figures 13a and 14a]. Supraskirtal AR [Figures 13c and 14c] may occur if the prosthesis is implanted too low in the aortic position.[455455565758]

Figure 14

Different types of regurgitation in transcatheter valves. (a) Transvalvular aortic regurgitation (b) Paravalvular aortic regurgitation, and (c) Supraskirtal regurgitation

ROLE OF 3D-ECHOCARDIOGRAPHY

Three-dimensional (3D) TEE allows an accurate assessment of prosthetic discs and planimetric evaluation of the prosthetic area [Figure 15]. However, 3D-Eco is superior to 2D-TEE, especially in the assessment of paravalvular leak regurgitation (PVL) that it provides improved localization and analysis of the PVL size and shape [Figures 16–18].[5960616263] To facilitate the communication between the interventionalist and echocardiographer, it is recommended that leak location be reported in a clockwise format from a ‘surgical view’ [Figure 18]. Aortic PVLs are more commonly located in the right and noncoronary cusps.[40] Mitral PVL location can also be reported in a similar format as the aortic valve [Figure 18]. By rotation of the echocardiographic image, the aortic valve is brought to a position at the top of the mitral ring, as viewed from the atrium.[616263] The most common locations for mitral PVLs are near the anterolateral commissure.[626364656667]

Figure 15

Three-dimensional TEE ofa mitral prosthetic discs

Figure 16

(a) Three-dimensional TEE ofa mitral paravalvular leak (b) Three-dimensional colorDoppler imaging of the paravalvular leak with arrow identifying the regurgitant jet. (c) Measurements of length, width, and area

Adapted from Chad Kliger et al. Review of surgical prosthetic paravalvular leaks: Diagnosis and catheter-based closure. European Heart Journal 2013; 34: 638-648.

Figure 18

Aortic and mitral valves from a surgeon's perspective H = Head, LAA = Left atrial appendage, LC = Left coronary cusp, LM = Left main coronary artery, NC = Noncoronary cusp, P = Posterior, R = Right, RC = Right coronary cusp, RCA = Right coronary artery

Three-dimensional TEE ofa mitral paravalvular posteromedial leak as seen from surgical view