Abstract
Background
A number of transcatheter-based therapies are emerging as therapeutic options for high–surgical risk patients with moderate-to-severe or severe mitral regurgitation (MR).
Case Summary
This is the first published report of treatment with the fully percutaneous, transfemoral, transseptal Saturn mitral valve replacement device in a 66-year-old woman with 3+ symptomatic MR. Ultimately, the patient had elimination of her MR and symptomatic improvement.
Discussion
This transcatheter mitral valve replacement device allows for basal annular stabilization and preservation of the neo–left ventricular outflow tract. Despite the difficult anatomy (small left heart size and limited transseptal height), device implantation was successful with the Saturn delivery system.
Take-Home Message
Saturn transcatheter mitral valve replacement offers a feasible alternative for the treatment of secondary MR.
Key words: mitral regurgitation, transcatheter mitral valve replacement
Graphical Abstract
The patient is a 66-year-old woman who presented with shortness of breath on exertion (NYHA functional class III symptoms) and was found to have 3+ mitral regurgitation (MR). Her symptoms persisted despite goal-directed medical therapy and cardiac resynchronization therapy. She was evaluated by the local heart team and deemed high risk to undergo cardiac surgery (European System for Cardiac Operative Risk Evaluation II value 3.14%, and Society of Thoracic Surgeons predicted risk of mortality for mitral valve replacement and mitral valve repair was 6.7% and 4.2%, respectively) because of her comorbidities including a low body mass index and frail appearance.
Past Medical History
The patient was a current smoker and had medical comorbidities of low body mass index (19 kg/m2), paroxysmal atrial fibrillation, type II diabetes mellitus, chronic kidney disease, and nonischemic cardiomyopathy with a cardiac resynchronization therapy defibrillator device in place. She had the cardiac resynchronization therapy defibrillator implanted 3 months prior because of atrioventricular block in the setting of a reduced ejection fraction. Her medical therapy included an angiotensin receptor/neprilysin inhibitor, carvedilol, torsemide, spironolactone, dapagliflozin, and rivaroxaban.
Investigations
Echocardiography demonstrated a moderately reduced left ventricular ejection fraction and moderate-to-severe functional MR by multiparametric assessment with restricted posterior leaflet motion. The mitral valve stroke volume was 113.7 mL, with a regurgitant volume and regurgitant fraction of 76.5 mL and 67%, respectively. The effective regurgitant orifice area by quantitative Doppler was 37 mm2. There was evidence of systolic flow reversal in the pulmonary veins. The right ventricular function was mildly reduced with mild tricuspid regurgitation. The pulmonary artery systolic pressure was estimated to be 38 mm Hg.
Cardiac computed tomography (CT) imaging demonstrated an annular perimeter of 112.7 mm in end systole with small left atrium (LA) size (Table 1, Figure 1). The minimum average right iliofemoral venous diameter was 9.7 mm.
Table 1.
Cardiac CT Evaluation
| End Systole | End Diastole | |
|---|---|---|
| Perimeter (mm) | 112.7 | 120 |
| Annular area (cm2) | 9.6 | 10.8 |
| IC (mm) | 35.8 | 40.8 |
| AP (mm) | 31.3 | 31.6 |
| TT (mm) | 29.0 | 27.5 |
| Anterior leaflet length (mm) | Not measured | 20.5 |
| Posterior leaflet length (mm) | Not measured | 10.3 |
| LA height (mm) (from the MV plane) | 49.7 | 39.8 |
| LA diameter (mm) (at the predicted puncture location) | 46.6 | 42.3 |
| LV diameter (AP) (mm) | 44.1 | 52.3 |
| LV diameter (IC) (mm) | 47.0 | 58.7 |
AP = anterior-posterior; CT = computed tomography; IC = intercommissural; LA = left atrial; LV = left ventricle; MV = mitral valve; TT = trigone to trigone.
Figure 1.
Preprocedural Cardiac CT Assessment and Procedure Planning
(A) Mitral annular dimensions in end systole. (B, D) Left atrial and ventricular anatomy in end systole and end diastole demonstrating small left atrial size. (C) Predicted neo-LVOT in end systole of 259 mm2. (E) Fluoroscopic simulation of the delivery catheter in a coplanar and short-axis view. (F) Three-dimensional volume reconstructed CT images demonstrating delivery catheter path and the neo-LVOT after valve implantation. AP = anterior-posterior; CT = computed tomography; IC = intercommissural; LVOT = left ventricular outflow tract.
Blood work was unremarkable other than the creatinine level of 1.36 mg/dL (estimated glomerular filtration rate of 34 mL/min/1.73 m2).
Management
The patient was not an optimal candidate for transcatheter mitral edge-to-edge repair due to a small mitral valve area of only 3.2 cm2. After discussion by the heart team, the patient was screened for the CASSINI-EU early feasibility study (EFS), which is evaluating the Saturn transseptal transcatheter mitral valve replacement (TMVR) system. The Saturn valve has 2 main components forming a unit with an interlocked design. First, the native mitral leaflets are embraced in the subannular space with 2 annular segments. The annular segments are then connected to the central valve via a set of connecting arms providing a mechanical bond between the 2 components (Figure 2). The cardiac CT demonstrated adequate anatomy with an annular perimeter suitable for a 28-mm valve. The estimated neo-LVOT (left ventricular outflow tract) in early and late systole with virtual valve modeling was 316 mm2 and 259 mm2, respectively.
Figure 2.
Saturn Transcatheter Mitral Valve Replacement
(A) The subvalvular structure is developed by creating 2 loops around the medial and lateral side of the mitral annulus over which annular segments are placed. (B) The central valve is then connected to the annular segments via 2 connecting arms, anteriorly and posteriorly. (C) The valve is then deployed. TMVR = transcatheter mitral valve replacement.
The patient was approved by the screening committee, and approval was obtained from the local ethics committee. Informed written consent was obtained from the patient.
The procedure was performed under general anesthesia with transesophageal echocardiogram guidance. Percutaneous transfemoral access was obtained and preclosed with 2 sutures. A transseptal puncture was performed at 3.0 cm above the mitral annulus. Then, the 29-F delivery system was advanced into the LA. After formation of the annular ring (Video 1), the valve was inserted and deployed (Videos 2 and 3). Figure 3 and Video 4 provide a step-by-step overview of the procedural steps of the TMVR system.
Figure 3.
Transfemoral Transseptal Mitral Valve Replacement Procedure
(A) The guidewire delivery system is positioned at A2 and P2. (B, C) In the subvalvular space, 2 loops are formed medially and laterally from P2 to A2. To complete each loop, the guidewire is snared in the ascending aorta. (D) After completion of the 2 loops, annular segments are introduced over the guidewire rails. (E) The valve is connected to the annular segments via the anterior and posterior connecting arms. (F) The valve is then deployed.
Hemodynamics remained stable throughout the procedure. Echocardiographic imaging demonstrated a good final implant position with no residual MR. Laminar flow was evident in the LVOT (Figure 4, Video 5). The dimensions of the iatrogenic atrial septal defect were 8 mm × 3 mm with left to right shunting after the delivery system was withdrawn, and therefore it did not require closure.
Figure 4.
Preprocedural and Postprocedural Echocardiographic Assessment
(A) Long-axis view. (B) Three-dimensional en-face view of the mitral valve. (C) Two-dimensional color Doppler of the mitral valve demonstrating 3+ mitral regurgitation. (D) Two-dimensional echo view of Saturn transcatheter mitral valve replacement prosthesis. (E) Color Doppler through the Saturn bioprosthesis demonstrating the absence of paravalvular leak. (F) Color Doppler through the aortic valve demonstrating laminar flow in the left ventricular outflow tract.
The procedure was completed in 3 hours, and the patient was extubated at the conclusion of the procedure and mobilized on postprocedure day 1.
Follow-Up
The patient had no procedure-related complications and was discharged in good clinical status on postprocedure day 3 on oral anticoagulation with warfarin. On the transthoracic echocardiogram before discharge, the mean transmitral gradient was 4.2 mm Hg. Cardiac CT was performed on postprocedure day 8 and demonstrated favorable valve positioning with a neo-LVOT of 295 mm2 in end systole (Figure 5). At 30-day follow-up, the patient had sustained elimination of MR and favorable bioprosthetic valve function (mean transmitral gradient 4.3 mm Hg and effective orifice area 2.1 cm2). The left ventricular ejection fraction increased from 39% at baseline to 46%. The patient is currently 3 months post-TMVR and is clinically doing well with NYHA functional class II symptoms. Her 6-minute walk test increased almost 2-fold, from 229 m at baseline to 401 m at 3 months.
Figure 5.
Cardiac CT Assessment Post-Implant
(A) Three-dimensional (3D) rendering of the left ventricular long-axis view with Saturn TMVR prosthesis in place demonstrating widely patent neo–left ventricular outflow tract. (B) Short-axis view of the TMVR prosthesis in 3D. (C) Short-axis view of the TMVR prosthesis in 2D with normal appearing leaflets. CT = computed tomography; TMVR = transcatheter mitral valve replacement.
Discussion
There are multiple TMVR systems under development; however, there remains a high screen failure rate for these devices due to a multitude of reasons. Common reasons for anatomic screen failure include risk of LVOT obstruction and annulus size (either too small or large).1,2
The Saturn TMVR device has unique design features that address some of these issues. First, the valve preserves the neo-LVOT as the anterior connecting arm immobilizes the anterior leaflet preventing systolic anterior motion of the leaflet and has a low profile stent frame in the left ventricle (13 mm). Second, the annular structure is mechanically connected to the valve, which allows for basal annular stabilization and provides the ability to reduce the mitral annulus size. The 2 valve sizes available can treat annular perimeters between 90 and 146 mm. Last, the delivery system has a small bending radius that allows for valve implantation in patients with small left atrial and ventricular anatomy. The minimum transseptal height required for implantation is yet to be defined. However, as demonstrated in this case, implantation is possible in patients with a maximum transseptal height of 3 cm. In addition, the Saturn valve was successfully implanted with the same delivery system in the porcine model with a typical transseptal height of approximately 1.5 cm and small left-sided anatomy (LA height ranges between 2.5 and 3.0 cm).3
The Saturn valve was first clinically validated in transapical implantation and has demonstrated safety and feasibility in an initial EU EFS study. Patients at this point have been followed for 2 years. There have been no mortalities, the patients are doing well clinically, and all patients have demonstrated resolution of MR and stable valve function.4 Conceptually, the same valve is being used with the transseptal delivery system that has been used for the transapical patients. The delivery system and steps for transseptal delivery of the valve were developed and validated in a preclinical model.3 The patient presented here is part of the early experience in the transseptal EFS.
Conclusions
This first reported case of transseptal TMVR with the Saturn valve demonstrates the feasibility and utility of this device.
Funding Support and Author Disclosures
This study was sponsored by InnovHeart. Dr Vahl reports institutional funding to Columbia University Irving Medical Center from Abbott Vascular, Boston Scientific, Edwards Lifesciences, JenaValve, and Medtronic. He personally received consulting fees from Abbott Vascular, InnovHeart, and Philips. Dr Ranard reports institutional funding to Columbia University Irving Medical Center from Boston Scientific and consulting fees from Philips, 4C Medical, and InnovHeart. Dr Denti reports Speaker Honoraria from Abbott and consulting fees from Approxima, HVR, InnovHeart, Picardia, and Simulands. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.
Take-Home Messages
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Saturn transcatheter mitral valve replacement offers a feasible alternative for the treatment of secondary mitral regurgitation.
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This novel transcatheter mitral valve replacement system is useful for the treatment of secondary mitral regurgitation in patients with small left atrial anatomy and limited transseptal height.
Footnotes
The authors attest they are in compliance with human studies committees and animal welfare regulations of the authors’ institutions and Food and Drug Administration guidelines, including patient consent where appropriate. For more information, visit the Author Center.
Appendix
For supplemental videos, please see the online version of this paper.
Appendix
Completed Annular Ring Visualized by 3-Dimensional Transesophageal Echocardiography
Flaring of the Valve Within the Annular Ring Before Release as Visualized by Fluoroscopy
Final Release of the Valve Within the Annular Ring
Procedural Animation of the Steps for Implantation of the Transfemoral Saturn Transcatheter Mitral Valve Replacement System
Color Doppler Evaluation of the Saturn Valve in a 3-Chamber Transesophageal Echocardiographic View
References
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
Completed Annular Ring Visualized by 3-Dimensional Transesophageal Echocardiography
Flaring of the Valve Within the Annular Ring Before Release as Visualized by Fluoroscopy
Final Release of the Valve Within the Annular Ring
Procedural Animation of the Steps for Implantation of the Transfemoral Saturn Transcatheter Mitral Valve Replacement System
Color Doppler Evaluation of the Saturn Valve in a 3-Chamber Transesophageal Echocardiographic View