This protocol presents in detail how to perform real-time echocardiographic guidance during transcatheter mitral valve repair. The fundamental views and the necessary measurements are described for each stage of the procedure.
Percutaneous transcatheter edge-to-edge reconstruction of the mitral valve is a safe and well-established therapy for severe symptomatic mitral regurgitation in patients with high surgical risk. Echocardiographic guidance in addition to fluoroscopy is the gold standard and should be performed using a standardized technique.
This article lays out our reproducible step by step echocardiographic guide including views, measurements as well as highlighting possible difficulties that may arise during the procedure.
This article provides detailed and chronological echocardiographic views for each step of the procedure, especially preferences between 2D and 3D imaging. If needed, pulse wave, continuous wave and color doppler measurements are described. Furthermore, as there are no official recommendations for the quantification of mitral regurgitation during the percutaneous edge-to-edge-repair procedure, advice is also included for echocardiographic quantification after grasping the mitral leaflets and after device deployment. In addition, the article deals with important echocardiographic views to prevent and deal with possible complications during the procedure.
Echocardiographic guidance during transcatheter mitral valve repair is mandatory. A structured approach improves the collaboration between interventionist and imager and is indispensable for a safe and effective procedure.
Mitral regurgitation (MR) is the second-most frequent indication for valve surgery in Europe1. Untreated, it may lead to severe heart failure and reduced quality of life2,3,4. The percutaneous mitral valve repair (PMVR) is a catheter-based technique, which mimics the Alfieri stitch surgical method to mitral repair by connecting the A2 and P2 scallops5. For patients with high surgical risk, this technique offers a minimally invasive approach for the treatment of severe MR. Data from several registries and trials has shown that the MitraClip procedure, a transcatheter mitral valve repair therapy, is an effective and safe method6,7,8,9. In 2019, a similar device, the PASCAL transcatheter valve repair system, was introduced to the market. It has shown feasibility and acceptable safety in the treatment of patients with severe MR10. The duration and success of the PMVR are dependent on the individual operator's skill and experience11. In contrast to other percutaneous techniques, like the percutaneous transvalvular replacement (TAVR), which can be done with fluoroscopy only, PMVR requires echocardiographic guidance12,13.
This article describes step by step the echocardiographic approach during PMVR, including measurements, suggestions for intraprocedural quantification of the MR and important views to prevent periprocedural complications.
The protocol follows the guidelines of our's institution's human research ethics committee.
1. Evaluation before intervention
Figure 1: Modified SAX view: PW flow in the left upper pulmonary vein Please click here to view a larger version of this figure.
Figure 2: 2D biplanar view of the MV with color doppler: medial insufficiency jet Please click here to view a larger version of this figure.
Figure 3: Multiplanar reconstruction of the 3D dataset with color doppler: 3D-Vena contracta Please click here to view a larger version of this figure.
Figure 4: Wide sector zoom image: 3D en-face surgical atrial view (aortic valve at 12 o'clock) Please click here to view a larger version of this figure.
Figure 5: Wide sector zoom image: 3D en-face atrial view (aortic valve at 6 o'clock) Please click here to view a larger version of this figure.
2. Strategy
3. Transseptal puncture
Figure 6: 2D biplanar view: transseptal puncture Please click here to view a larger version of this figure.
4. Introduction of the SGC into the LA
5. Advancement of the CDS into the LA
Figure 7: Wide sector zoom image: SGC in the LA including the interatrial septum, the left lateral ridge and the MV Please click here to view a larger version of this figure.
6. Orientation of the device above and below the MV
Figure 8: 2D biplanar view of the MV: positioning of the device over the mitral valve Please click here to view a larger version of this figure.
Figure 9: Wide sector zoom image: positioning of the device over the mitral valve Please click here to view a larger version of this figure.
NOTE: The clip arms are visible only in the LAX view.
7. Grasping of the mitral leaflets and assessment of MR before and after clip deployment
Figure 10: Wide sector zoom image: double orifice of the MV after device deployment Please click here to view a larger version of this figure.
8. Final MR assessment
9. Implantation of additional devices
Percutaneous edge-to-edge valve repair is an alternative to surgical valve repair or replacement in patients not eligible for surgery with symptomatic severe MR. The first clinical application of the MitraClip was investigated in the Endovascular Valve Edge-to-Edge Repair Study I (EVEREST I)14 trial. Many other trials have proven the effectiveness of the procedure with an improvement of symptoms as well as low rates of hospital mortality and adverse events (ACCESS EU, TRAMI, EVEREST II)15,16,17. Percutaneous edge-to-edge procedures have been incorporated into the European guidelines for the intervention of primary and secondary MR18. Two randomized trials MITRA-FR and COAPT compared the MitraClip procedure with optimal medical therapy and verified the feasibility of this intervention in patients with secondary MR. Although MITRA-FR did not show any significant benefit for the MitraClip group concerning the composite endpoint (all-cause mortality and rehospitalization for heart failure) at 12 months19 (Supplementary Figure 15), COAPT showed significant superiority of the MitraClip in terms of mortality and rehospitalization rates, compared to the conservative treatment alone at 24 months20 (Supplementary Figure 16). Compared with patients in the COAPT trial, those enrolled in the MITRA-FR trial had substantially more left ventricular damage and less severe MR due to the use of different classifications of MR (Supplementary Figure 17). To classify severe MR MITRA-FR used the 2012 European guidelines21, whereas COAPT used the 2006/2008 American guidelines22, which may explain the different outcomes observed in these two trials.
Since 2019, another device for transcatheter mitral valve repair has become available. Compared to the MitraClip device, the PASCAL system has wider paddles. It can independently grasp leaflets, as the fourth generation MitraClip, in the presence of a central spacer. After a multi-centre, prospective, observational, first-in-man study23 and the multi-centre early-feasibility trial of the PASCAL transcatheter mitral repair device (CLASP study), the PASCAL repair system received CE mark approval for the treatment of both primary and secondary MR. The early feasibility study of the PASCAL repair system showed high survival, low complication rates as well as improvements in functional status and quality of life (Supplementary Figure 18). Furthermore, the CLASP study showed a significant reduction of the MR with this device. As there are no head-to-head studies available yet, the preferred device related to the valve anatomy (e.g., larger flail segments, large prolapse, cleft, short posterior leaflet, mitral annular calcification) is still not defined. A head-to-head comparison trial of the MitraClip with the Pascal System (CLASP IID trial) started in 2018 and the estimated primary completion date is expected to be in 2023.
A critical appraisal of echocardiographic assessment of MR, especially a functional one, is still to be done.
Because of its complex structure, the MV is altered by dynamic changes24 and quantification of MR requires an understanding of the normal valve anatomy. The echocardiographic guidelines for the quantification of native valvular regurgitation have been updated in 2017.25 Official recommendations for the quantification of valve regurgitation after percutaneous valve repair have been available since 2019.26 Due to missing validation of 2D vena contracta and EROA in multiple jets, neither 2D vena contracta nor EROA and regurgitant volume/fraction by PISA is recommended after PMVR (Supplementary Figure 19). Thresholds for 3D-VCA were first introduced and 3D-VCA gained a relevant role for the quantification of valve regurgitations which is superior to the 2D PISA method27,28. 3D-VCA is highly dependent on good image quality. Therefore, semi-quantitative parameters such as the signal intensity of the CW doppler of the MR-jet, the pulmonary vein flow pattern and the mitral inflow pattern are still necessary29.
Although the utility of 3D-VCA has not yet been fully validated to assess MR, further development of 3D technologies will probably improve its value.
Continuous hemodynamic monitoring may complement transesophageal echocardiography to assess and optimize percutaneous edge-to-edge mitral valve repair. Previous studies demonstrate the value of real-time monitoring of LA pressure during PMVR30,31,32,33. An increase in left atrial mean pressure is predictive of worse clinical outcomes at short-term follow-up, independent from echocardiographic findings.
Supplementary Figure 1: Modified bicaval view: PW flow in the right upper pulmonary vein Please click here to download this File.
Supplementary Figure 2: 2D biplanar view of the MV: length of the PML Please click here to download this File.
Supplementary Figure 3: Multiplanar reconstruction of the 3D dataset: mitral valve area in 3D Please click here to download this File.
Supplementary Figure 4: 2D biplanar view of the MV with color doppler: medially implanted device and residual lateral insufficiency jet Please click here to download this File.
Supplementary Figure 5: 4Ch view: puncture height Please click here to download this File.
Supplementary Figure 6 SAX view in 2D: SGC with echo bright double ring Please click here to download this File.
Supplementary Figure 7: 2D biplanar view of the MV: advancement of the CDS into the LA Please click here to download this File.
Supplementary Figure 8: Wide sector zoom image: advancement of the CDS into the LA Please click here to download this File.
Supplementary Figure 9: 2D biplanar view of the MV: grasping of the leaflets Please click here to download this File.
Supplementary Figure 10: 2D biplanar view of the MV with color doppler: residual insufficiency jets Please click here to download this File.
Supplementary Figure 11: LAX in 2D: transmitral pressure gradient before device deployment Please click here to download this File.
Supplementary Figure 12: Intercommissural view in 2D: transmitral pressure gradient after device deployment Please click here to download this File.
Supplementary Figure 13: 2D biplanar view of the MV: delivery catheter tip Please click here to download this File.
Supplementary Figure 14: Multiplanar reconstruction of the 3D dataset with color doppler: 3D-VCA after device deployment Please click here to download this File.
Supplementary Figure 15: MITRA-FR Trial: Kaplan-Meier Estimates of Survival without a Primary Outcome Event Please click here to download this File.
Supplementary Figure 16: COAPT Trial: Primary Effectiveness and Safety End Points and Death Please click here to download this File.
Supplementary Figure 17: MITRA-FR vs. COAPT: Similarities and differences between MITRAFR and COAPT with respect to baseline characteristics of the study populations Please click here to download this File.
Supplementary Figure 18: CLASP Study: Functional and Clinical Paired Analyses at Baseline and 30 Days for the PASCAL Transcatheter Valve Repair System Please click here to download this File.
Supplementary Figure 19: Guidelines for the Evaluation of Valvular Regurgitation After Supplementary Percutaneous Valve Repair or Replacement: Echocardiographic parameters and related comments in the assessment of MR severity with TTE after transcatheter MV interventions Please click here to download this File.
Echo-guidance for the PMVR is a safe method. Complications due to echocardiography may occur but rarely lead to significant damage. Nevertheless, esophageal lesions are possible after performing transesophageal echocardiography. This incidence is reduced with a shorter duration of the intervention34. On the contrary, several complications associated with the transcatheter edge-to-edge mitral valve repair are described35,36. Major bleeding is the most frequent major complication and blood transfusion after transcatheter valve procedures have been strongly associated with mortality37. Pericardial tamponade is rare and may occur during several steps of the procedure. Caution during transseptal puncture, insertion of the SGC into the left atrium and retrieving of the SGC-tip after clip deployment reduces the probability of this life-threatening complication. Rates of clip-specific complications, as embolization and partial clip detachment, are low and can be reduced by an accurate echocardiographic assessment during and after grasping of the leaflets.
Despite the carefulness during echocardiography, aggravation of the MR, may occur. Additional clip deployment in the medial and lateral position may increase the risk of entangling and rupturing of the chordae38. Furthermore, repeated grasping of the leaflets can lead to leaflet laceration and perforation. Residual MR is not only a determinant of procedural success but is also associated with poorer prognosis39,40, especially when there is a concomitant transmitral pressure gradient >5 mm Hg41,42. Clear communication with the interventionist and a meticulous echocardiographic assessment are necessary to reduce peri-procedural clip-related complications.
The percutaneous edge-to-edge repair is not eligible for every pathomechanism of MR. For some determinants of MR, such as annulus dilatation, rupture of the chordae tendinae or severe calcifications of the mitral leaflets, the device reaches its limits. In this case, mitral ring dilation can be sutured surgically or percutaneously in place to provide annular stabilization. Polytetrafluoroethylene (PTFE) neochordae can be surgically sewed as new chordae tendinee. A MV with severe calcified leaflets may be replaced with a prosthetic valve. New percutaneous devices designed to address these aspects are under development.
A structured echocardiographic approach for the PMVR is mandatory. Several techniques of how to perform echoguidance for the PMVR procedure have been described43,44,45,46,47,48. In our opinion, it is important to define a detailed sequence of steps together with the interventionist, which should be performed during every intervention. Although the 3D en-face view is defined showing the aortic valve at 12 o'clock, many centres prefer the "cardiologist" 3D en-face view, which shows the aortic valve at 6 o'clock. There is no literature comparing both views during the PMVR. Several options for the assessment of specific views in 2D or 3D as well as for the quantification of MR are available. 3D transesophageal echocardiography allows the measurement of each orifice after edge-to-edge repair. The guidelines propose thresholds for 3D-VCA as <0,2cm2 for mild, 0,2-0,39 cm2 for moderate and ≥ 0,4 cm2 for severe regurgitation26. Previous studies have shown that improvement of clinical symptoms correlates to a significant reduction of the 3D-VCA, independently from an absolute value49. Furthermore, reduction of left atrial and ventricular volume is significantly greater in patients who show a reduction in 3D-VCA of more than a 50% after MV repair50. Our experience confirms this data. Nevertheless, the percentual reduction of the 3D-VCA required to significantly improve a severe MR has not been defined. Further validation of this method is needed and the assessment of other parameters for the adequate evaluation of residual MR remains indispensable. Due to possible mild mitral stenosis caused after clip implantation, the MV inflow pattern rarely gives additional information to the MR reduction. On the contrary, the pulmonary flow pattern is a reliable parameter and predicts recurrent MR and worse long-term outcomes.
In conclusion, percutaneous transcatheter mitral valve repair is fully dependent on transesophageal echocardiography. Both, the imager and the interventionist should have a fundamental understanding of echocardiographic assessment to achieve a successful and safe procedure.
The authors have nothing to disclose.
We thank Ms. Dorothea Scheurlen for technical video support.
EPIQ 7 Ultrasound System | Philips | US218B0542 | Cardiac Ultrasound Machine |
X8-2t xMATRIX 3D-TEE probe | Philips | B34YYK | TEE-probe |
Sheath 6F 25 cm | Merit Medical | B60N25AQ | Sheath |
Dilator 16 F | Abbott | 405544 | Dilator |
BRK-1 transseptal needle 71 cm | St. Jude Medical | ABVA407201 | Transseptal Needle |
Swartz Lamp 90° | St. Jude Medical | 407356 | Transseptal Guiding Introducer Sheath |
Amplatz super stiff | Kook Medical | 46509 | Wire |
Steerable Guide Catheter | Abbott | SGC0302 | Steerable Guide Catheter |
MitraClip NTR Delivery System | Abbott | CDS0602-NTR | Clip Delivery System |
MitraClip NTR Bundle | Abbott | MSK0602-NTR | Device |