REVIEW ARTICLE

Year : 2022  |  Volume : 6  |  Issue : 3  |  Page : 227-235

Transesophageal Echocardiography for Mitral Valve Transcatheter Edge-to-Edge Repair

Nitin J Burkule¹, Manish Bansal^2
1 Department of Cardiology, Jupiter Hospital, Thane, Maharashtra, India
² Department of Cardiology, Medanta- The Medicity, Gurugram, Haryana, India

Correspondence Address:
Dr. Nitin J Burkule
Department of Cardiology, Jupiter Hospital, E. Ex. Highway, Thane - 400 606, Maharashtra
India

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jiae.jiae_40_22

Transcatheter edge-to-edge repair (TEER) has emerged as a viable treatment option for patients with degenerative or functional severe mitral regurgitation (MR) who are at high risk for mitral valve surgery but have mitral valve anatomy suitable for TEER. The MitraClip and Pascal repair system are the two TEER devices currently approved for clinical use for transcatheter treatment of MR in selected patients. Of these two, the MitraClip has become a more established modality for TEER and is currently available in India. This review describes the role of echocardiography in patient selection and procedural guidance during TEER with MitraClip.

Keywords: COAPT trial, MitraClip, Pascal repair system, primary mitral regurgitation, secondary mitral regurgitation

Introduction

MitraClip Design

Figure 1: MitraClip design and different variants Click here to view

Role of Echocardiography in Transcatheter Edge-to-Edge Repair with MitraClip

1. Carpentier type II MR (AML or PML A2/P2 segment prolapse or flail): TEER may be considered in symptomatic patients^[2],[3] (class IIb B) if the following conditions are met:



1. Eligible by echocardiographic criteria (discussed subsequently),
2. A heart team evaluation considers the patient inoperable or at high surgical risk, and
3. The procedure is not considered futile by the heart team.



2. Secondary MR: TEER is beneficial in patients with persistent symptoms (with at least one heart failure hospitalization within the previous year or increased natriuretic peptide levels) without hemodynamic instability, shock, or ongoing inotropic or mechanical circulatory support^[2],[3] (class IIa B), if:



1. On optimized guideline-directed medical therapy and, when indicated, cardiac resynchronization therapy,
2. Eligible by echocardiographic criteria,
3. Left ventricular ejection fraction (LVEF) between 20% and 50%, and
4. Not undergoing surgical revascularization.

1. Effective regurgitant orifice area (EROA) by 2D proximal isovelocity surface area (PISA) method >40 mm² (a lower cutoff value of >30 mm² may be acceptable in secondary MR due to elliptical regurgitant orifice)
2. Regurgitant volume >60 mL (per beat) for primary MR and >45 mL in secondary MR (if low LV stroke volume)
3. Regurgitant fraction >50%. In secondary MR, due to low stroke volume, regurgitant fraction is a more reliable measure of MR severity than regurgitant volume.

• No rheumatic heart disease
• No infective endocarditis
• LVEF 20%–50%
• LV end-systolic diameter <70 mm
• Leak from A2 to P2 scallops
• Single/dominant central jet
• Mitral valve orifice area (MVA) >4.0 cm² on 3D TEE
• Baseline mitral valve mean gradient <3 mmHg
• Estimated pulmonary artery systolic pressure <70 mmHg
• No evidence of moderate or severe right ventricular systolic dysfunction
• Transseptal crossing height from mitral annulus >4 cm
• No calcification at the leaflet grasping site
• Secondary MR: Leaflet coaptation depth <11 mm and coaptation length >2 mm [Figure 2]^[6]
• Carpentier type II MR (A2/P2 prolapse/flail): Non-tethered PML length >10 mm, flail width <15 mm, and flail gap <10 mm [Figure 3].^[7]

Figure 2: Echocardiographic criteria for suitability for transcatheter edge-to-edge repair in a patient with secondary mitral regurgitation Click here to view

Figure 3: Echocardiographic criteria for suitability for transcatheter edge-to-edge repair in a patient with degenerate mitral regurgitation. (a) A patient with flail anterior mitral leaflet, (b) a patient with flail posterior mitral leaflet. PML: Posterior mitral leaflet Click here to view

• Carpentier type IIIA abnormality (e.g., rheumatic MR)
• Infective endocarditis
• Left atrial (LA)/LA appendage clot
• Calcification of the leaflets at the grasp site
• Mitral valve mean gradient >5 mmHg
• MVA <3 cm² on 3D TEE
• Severe right ventricular systolic dysfunction and pulmonary hypertension unrelated to MR
• Atrial septal defect (ASD) closure device in situ
• Inferior vena cava thrombosis.

• Commissural prolapse involving A1–P1 or A3–P3 scallops
• Large AML prolapse with ruptured chordae
• Multisegment prolapse/flail (Barlow's disease)
• Cleft in the leaflet as the major source of MR
• Previous mitral valve repair/ring annuloplasty surgery
• Severe mitral annular calcification involving PML with <5 mm of leaflet available for grasping
• Leaflet or chordal calcification at the grasping site
• Mobile PML length <7 mm
• Tethering height >11 mm in secondary MR
• MVA 3–4 cm²
• Mitral valve mean gradient 4–5 mmHg
• Small LA size (medial-lateral diameter <3.7 cm)
• Lipomatous interatrial septum (IAS), patent foramen ovale, or previous surgical ASD closure or small ASD device closure
• 3D mitral valve annular area >140 cm²
• Annular dilatation: Adynamic mitral valve annulus with mitral annular height <7 mm
• LV size >70 mm or LV end-diastolic volume >120 ml/m².

1. Define the leaflet target and major MR jet
2. Guide the transseptal puncture
3. Guide safe steering of steerable guiding catheter (SGC) in the LA to advance the clip delivery system (CDS) to the targeted leaflets
4. Guide the alignment of clip arms perpendicular to the coaptation line
5. Confirm leaflet capture within the clip arms during the grasp maneuver
6. Assessment of MR reduction after clip arm closure and exclusion of significant mitral stenosis
7. Assessment of IAS shunt and procedural complications once SGC is removed.

1. Obtain pulsed-wave (PW) Doppler spectral tracing of right and left superior pulmonary veins
2. Obtain mitral valve PW Doppler velocity time integral for transmitral mean gradient
3. Measure MVA by planimetry in mid-diastole at the tip of mitral leaflets, either using 3D or in transgastric short-axis en face 2D view of the mitral valve
4. Obtain PW velocity time integral of the LVOT flow in the 2D TEE transgastric view as a surrogate for LV stroke volume
5. Some of the latest echocardiography systems have the capability to automatically compute aortic and mitral stroke volumes and thus MR regurgitant volume and fraction from 3D CFD data. If this capability is available, then the same can be utilized for quick, automated assessment of MR severity at various stages of the TEER procedure.
6. Look for any preexisting pericardial effusion. Rule out intracardiac clots.

• While guiding the IAS puncture, the 2D TEE bicaval view (90°–120°) is used for superior-inferior orientation and the short-axis view (45°–60°) for anteroposterior orientation [Figure 4] and [Video 1]
• Using biplane imaging, one can set bicaval view as the primary image and follow the sharp tenting caused by the septal puncture needle as the needle is withdrawn from the superior vena cava into the LA. The orthogonal imaging plane should be constantly positioned on the tenting site to obtain the secondary short-axis image showing the needle tip location
• It is important to avoid the center of fossa ovalis, thick portion of the septum secundum, and the proximity to aorta or posterior atrial wall. Crossing through patent foramen ovale can lead to IAS tear and unfavorable trajectory.^[9] A highly mobile (aneurysmal) portion of IAS should be avoided as the puncture needle may injure the LA free wall^[9]
• Before septal puncture, the tenting site should be checked in 2D TEE, four-chamber view (0°–20°) to determine the distance between the puncture site and the mitral annular plane. Approximately 4–4.5 cm distance is considered adequate.^[8] If the leaflet coaptation is deeper in the LV, then <4 cm may also be acceptable. In contrast, if there is an excessive flail segment which needs to be grasped, then even >4.5 cm may be necessary. The height and position of the transseptal puncture can be lower for A1/P1 target and higher for A3/P3 target^[9]
• Biplane imaging (0°–30° and 90°–120°) is then used to guide the placement of 24F SGC which is advanced with a dilator over a stiff wire into the LA. The dilator of the SGC has an echogenic terminal end which appears like a stack of rings. Caution should be exercised to avoid the dilator tip touching the LA free wall. The dilator is removed once SGC tip is roughly 2 cm into the LA [Figure 5].

Figure 4: Use of biplane imaging for guiding interatrial septal puncture. The left image shows bicaval view for superoinferior orientation whereas the right image shows the short-axis view for anteroposterior orientation. The yellow arrow points to the tenting produced by the septal puncture needle Click here to view

Figure 5: Positioning of the steerable guide catheter (yellow arrow) in the left atrium Click here to view

• Biplane 2D TEE (four-chamber view as the primary image) with advancement/withdrawal of the probe (as needed) is used to visualize the SGC and CDS tips and guide the advancement of CDS. The CDS is advanced out of the SGC until the straddling of the radiopaque markers is seen on the fluoroscopy
• The operator should be immediately warned if the clip end is in proximity to the LA roof, LA free wall, pulmonary vein ostium, or the coumadin ridge
• The CDS is then steered down toward the mitral valve orifice [Figure 6]. As the CDS is flexed, its tip moves from its superior location in the LA to the mitral valve orifice, passing en route the ostium of the left upper pulmonary vein and the coumadin ridge but without touching these structures.^[8] Either a biplane imaging or a live multiplanar imaging (MPR view in Philips system and Flexi-slice in the General Electric system) with simultaneous three orthogonal planes + one 3D en face view of the mitral valve can be used to monitor the distal tip of the CDS^[9]
• The CDS tip should be positioned precisely at the target segments of the mitral leaflets. Biplane imaging with bicommissural view (45°–60°) for medial-lateral orientation and LVOT view (120°–135°) for anteroposterior orientation is used for guiding this step [Figure 7] and [Video 2]a, [Video 2]b. Continuous monitoring in this biplane view is needed to ensure correct positioning of the CDS at the origin of the MR jet.

Figure 6: Trajectory of the clip delivery system in the left atrium in the echocardiographic (left) and the fluoroscopic images Click here to view

Figure 7: Echocardiographic views for aligning the MitraClip with the mitral leaflet target site. (a) Bicommissural view for medial-lateral orientation, (b) left ventricular outflow tract view for anteroposterior orientation, and (c) the three-dimensional en face view from the left atrial aspect for aligning the clip perpendicular to the mitral leaflet coaptation line Click here to view

Figure 8: MitraClip with open clip arms, being aligned with the mitral leaflet target site. Biplane imaging is used to simultaneously display the bicommissural and the left ventricular outflow tract views. (a) Without color, (b) with color Doppler Click here to view

• For a successful grasp, it is crucial to ensure that the clip arms are exactly perpendicular to the coaptation line at the grasping site. To achieve this, the clip with arms opened is visualized in the 3D en face mitral valve view and the operator then rotates the clip clockwise or anticlockwise to orient it in the proper direction. The clip is oriented perpendicular (12 o'clock–6 o'clock) for A2–P2 target, slight clockwise (1 o'clock–7 o'clock) for A1–P1 target, and slight anticlockwise (11 o'clock–5 o'clock) for A3–P3 target [Figure 7]c^[9]
• Proper positioning of the clip in relation to the MR jet is confirmed using 3D CFD
• Once the proper orientation of the clip arms is achieved, the clip arms are closed to 60° and the clip is then advanced into the LV in the LVOT view below the mitral valve and the clip arms are opened once again. Both the clip arms should be seen in this LVOT view
• The torquing of the clip arms is avoided in the subvalvar area to prevent damage and entanglement of the chordae. To reassess the perpendicularity of the clip arms to the coaptation line, the 3D en face view of the mitral valve is obtained again, and the ultrasound gain is reduced such that the clip arms are visualized through the mitral leaflets.^[8] Alternately, one can use the transgastric short-axis view to locate the clip arms.

• While continuously imaging in the LVOT (120°–135°) view, the CDS with open clip arms is slowly withdrawn toward the mitral valve [Figure 10]. From the original LVOT long-axis grasping view (120°), the multiplane angle may need to be increased by approximately 10°–40° for A1/P1 pathologies and reduced by approximately 10°–40° for pathologies in the A3/P3 segment^[7]
• The leaflets “lapping” into the clip arms in both systole and diastole should be watched for [Video 4].^[8] Adequate leaflet insertion within the clips should be confirmed using multiple 2D views from 0° to 30°–60°–90°–145°. The last time that the leaflet tips can be well visualized is before the grippers come down and the clip arms are closed.^[7] The grippers are lowered when the adequate leaflet insertion (ideally >4 mm) of both the leaflets in the clip arms is confirmed. Lowering of the grippers traps the leaflet tissue between the gripper and the corresponding clip arm^[7]
• Back in the 120°–135° LVOT view, once the grippers are seen lowered, both the leaflets should appear taut over the clip arms with minimal lift
• The clip arms are closed under fluoroscopic imaging [Figure 11]. Single leaflet detachment can occur in 1%–5% of cases. Less than 2 mm insertion of the leaflet in the clip arm may increase the risk of clip detachment.^[7] To avoid this, it is important to ensure that adequate length of the leaflets is captured within the closed clip. One method to confirm this is to measure the PML and AML lengths in the four-chamber or LVOT view before the procedure and then remeasure the free leaflet length (outside the clip) in the same views after the clip closure. The difference between the two measurements indicates the captured length of the leaflets.^[9]

Figure 9: (a) Three-dimensional en face view from the left atrial aspect for aligning the clip perpendicular to the mitral leaflet coaptation line, (b) the clip is complete off-axis, (c) the clip has already been advanced into the left ventricle and is being visualized through the mitral valve leaflets by reducing the image gain Click here to view

Figure 10: Leaflet grasping in the left ventricular outflow tract view Click here to view

Figure 11: Closing the clip arms under fluoroscopic (left image) and echocardiographic (right image) guidance Click here to view

• 2D and 3D TEE CFD in all the standard views is used to qualitatively estimate the severity of residual MR. The vena contracta and PISA-derived EROA are not validated.^[8] However, the presence of PISA on CFD suggests significant MR
• The best way to assess the hemodynamic effect of reduction in MR on LA pressure is to perform PW spectral Doppler of left and right superior pulmonary veins [Figure 12]. No systolic flow reversal and restoration of systolic forward flow or increase in the systolic forward flow from the preprocedural status are the most robust indicators of significant reduction of MR^[8]
• The reduction of V-wave height and mean LA pressure on the invasive hemodynamic pressure tracing also confirm reduction in the MR severity
• LV stroke volume should be ascertained using PW Doppler at the LVOT in the 2D TEE transgastric view. If the LVOT velocity time integral postprocedure is more than the preprocedure, then it indirectly suggests a reduction in MR volume and augmentation of forward flow^[8]
• 3D TEE CFD can be used to compute mitral and aortic stroke volume and residual regurgitant volume and fraction
• The insertion of both the leaflets in the clip arms should be confirmed. The presence of any significant MR jet on either side of the clip should be looked for in various views and with the clip arms loosened and retightened. It may be necessary to reposition or upsize the clip to achieve satisfactory reduction of MR
• If there is a significant MR jet on either side of the clip or a significant MR jet emerges at a new location, then an additional clip may be necessary. If the MR increases in severity and changes its characteristics, then one should carefully look for any leaflet tear, single leaflet detachment, or chordal rupture^[7]
• Before deploying the second clip, the mean mitral gradient should be checked using PW Doppler and the MVA is calculated by planimetry. Planimetry is performed in mid-diastole, either in the 2D transgastric view or in the 3D en face view. The deployment of MitraClip converts a single-orifice mitral valve into a double orifice valve [Figure 13 and Video 7]. Areas of the two mitral valve orifices are measured separately and added to yield the total MVA. Ideally, the mean mitral gradient should be <4 mmHg and MVA >2 cm². The mean mitral valve gradient above 5 mmHg and MVA <1.5 cm² are associated with higher long-term mortality^[7-9]
• In the presence of a large flail gap/width or coaptation defect, “zip-and-clip'' technique can be used.^[7] The first clip is placed lateral or medial to the largest coaptation defect to reduce (partially zip) the coaptation gap/width, which makes it amenable to deploy additional clips at the desired location
• The clip should not be released if the mean mitral gradient is >5 mmHg or the mitral valve area by planimetry is <1.5–2 cm². Similarly, any additional clip should be avoided if the mean gradient is >4 mmHg or the mitral valve area is <3–4 cm²
• For commissural defects, it is advisable to start clipping from the periphery of the mitral valve to the center so that the second clip can be placed with less difficulty. Imaging can be challenging for second clip deployment due to artifacts resulting from the first clip.

Figure 12: Pulmonary vein flow pattern before (a) and after (b) the clip deployment. There is prominent systolic flow reversal before the procedure which is replaced by good forward systolic flow after the procedure Click here to view

Figure 13: Double-orifice mitral valve after the clip deployment Click here to view

• Look for large ASD shunt in all the standard 2D TEE views of the IAS [Figure 14]. 3D TEE may be used to planimeter the defect size. If a significant ASD (>10 mm) is present at the SGC entry site, the closure of the defect with an ASD occluder device may be needed^[8]
• Look for the appearance of new pericardial effusion or change in the size of preexisting pericardial effusion.

Figure 14: Residual atrial septal defect after the MitraClip procedure. (a) Color Doppler showing the left-to-right shunt through the defect, (b) pressure gradient across the defect Click here to view

Conclusions

References

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9.	Ramchand J, Miyasaka R. Periprocedural echocardiographic guidance of transcatheter mitral valve edge-to-edge repair using the MitraClip. Cardiol Clin 2021;39:267-80.
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