Mitral valve disease, when severe, often requires surgical mitral valve replacement (SMVR) when repair isn’t possible. However, bioprosthetic valve degeneration can limit long-term success, sometimes necessitating repeat SMVR, a risky procedure with significant complications. Transcatheter mitral valve replacement (TMVR) offers a less invasive alternative, particularly valve-in-valve (ViV) TMVR, which has emerged as a safe option for patients with degenerated bioprostheses who are high-risk for repeat surgery. This guide provides a step-by-step approach to transseptal ViV-TMVR using the Edwards SAPIEN 3 Transcatheter Heart Valve System. This percutaneous approach, via the femoral vein, avoids the need for a mini-thoracotomy. Early experience demonstrates its safety, efficacy, reduced morbidity, and faster recovery compared to conventional surgery.
A Step-by-Step Approach to ViV-TMVR
This detailed guide outlines the essential steps involved in transseptal ViV-TMVR, focusing on best practices and key considerations for a successful procedure. We will discuss the following steps in detail:
- Patient Selection
- Imaging
- Preparation
- Vascular Access
- Transseptal Puncture
- Valve Deployment
- Closure
1. Patient Selection: Identifying the Ideal Candidates
Careful patient selection is paramount. Transseptal ViV-TMVR is best suited for individuals with a degenerated mitral bioprosthesis at high risk for repeat open-heart surgery. However, certain factors can preclude a patient from being a good candidate. Previous atrial septal defect repairs or mitral valve surgery via a transseptal approach may complicate the procedure. Patients with a small left ventricular outflow tract (LVOT) and a long, calcified anterior mitral valve leaflet are at increased risk for LVOT obstruction, a serious complication. Severe patient-prosthesis mismatch is also a concern, as inserting a transcatheter valve into an already small bioprosthesis can worsen the problem. Active endocarditis, severe paravalvular leak (PVL), thrombosis, or bioprosthesis dehiscence are contraindications.
2. Imaging: Pre-operative Assessment and Planning
Comprehensive pre-operative imaging is crucial. Computed tomography (CT) is essential to assess the risk of iatrogenic LVOT obstruction. CT simulations with a virtual transcatheter valve can predict the neo-LVOT area after ViV-TMVR. A projected neo-LVOT area ≤1.7 cm2 indicates a high risk of postprocedural LVOT obstruction. CT is also used to measure the internal diameter of the existing bioprosthesis for proper transcatheter valve sizing. It can also identify rare anomalies like an interrupted inferior vena cava (IVC), which would make the transseptal approach impossible. Transesophageal echocardiography (TEE) identifies the cause of bioprosthetic failure and assesses the interatrial septum’s anatomy. If the septum cannot be visualized on TEE, transseptal ViV-TMVR cannot be performed. TEE also enhances safety and success in patients with a thickened atrial septum. Coronary angiography is recommended for patients at high risk for LVOT obstruction to identify the first septal perforator if pre-emptive alcohol septal ablation is needed.
3. Preparation: Setting Up for Success
The procedure takes place in a catheterization laboratory or hybrid fluoroscopy operating room with the patient in the supine position. A radial arterial line with a 20-gauge catheter is inserted for continuous hemodynamic monitoring. Following anesthesia induction, a TEE probe is placed for pre- and post-procedural mitral valve evaluation. The groins are prepped, and the patient is draped following standard surgical protocols.
4. Vascular Access: Gaining Entry to the Venous System
The bilateral common femoral veins are accessed using a 6 French (Fr) sheath under ultrasound (US) guidance (Seldinger technique). A Perclose Proglide device (Abbott Laboratories, Chicago, IL, USA) is proactively placed in the right femoral vein for suture-mediated closure of the venotomy used for large-bore sheath insertion. A steerable vascular access sheath, like the Agilis NxT Steerable Introducer (Abbott Laboratories, Lake Bluff, IL, USA), is advanced into the right femoral vein. Under fluoroscopy, the Agilis NxT Steerable Introducer is navigated up the IVC to the junction of the IVC and right atrium (RA).
5. Transseptal Puncture: Crossing the Atrial Septum
After administering 5,000 units of heparin systemically, a Mullins sheath (Cook Group, Bloomington, IN, USA) is inserted into the right femoral vein and advanced into the RA. An NRG transseptal needle (Baylis Medical, Burlington, MA, USA) is advanced through this sheath and carefully directed towards the fossa ovalis under TEE and fluoroscopic guidance. Radiofrequency energy is delivered through the transseptal needle to puncture the atrial septum, and the Agilis sheath is advanced into the left atrium (LA). Proper LA placement should be confirmed by transducing LA pressures. The transseptal needle is withdrawn, and an Inoue wire (Toray Medical Co., Ltd., Tokyo, Japan) is advanced through the sheath into the LA. Keeping the wires within the LA, the Agilis sheath is advanced further. The patient is then systemically heparinized, targeting an activated clotting time (ACT) of 250–350 seconds. The Agilis sheath is steered towards the left ventricular apex, and a standard J-wire is passed towards the left ventricle (LV). A pulmonary artery catheter can be advanced across the wire with the balloon inflated to confirm the lack of chordal entanglement. A pigtail catheter is then advanced into the LV over the J-wire. Finally, a temporary transvenous pacemaker is inserted through the left femoral venous sheath, floated up to the heart, and anchored into the trabeculae of the right ventricle.
6. Valve Deployment: Implanting the Transcatheter Valve
A Safari wire (Boston Scientific Corp., Marlborough, MA, USA) is advanced through the pigtail catheter, across the mitral valve, and into the apex of the LV using standard wire exchange techniques. Over the Safari wire, a 14 Fr Edwards eSheath (Edwards LifeSciences Corp., Irvine, CA, USA) is inserted. The interatrial septum is then dilated with a 14 mm balloon. The balloon is withdrawn, and an Edwards SAPIEN 3 Transcatheter Heart Valve System (Edwards LifeSciences Corp., Irvine, CA, USA) is advanced into the IVC. The valve must be mounted on the delivery catheter with the skirt towards the handle, opposite the direction used for TAVR. To load the valve, the sheath typically needs to be moved back to provide adequate space. After loading, the entire sheath is rotated 180 degrees clockwise, angling the device’s flexing mechanism rightwards, opposite of the leftward curve in TAVR. The device is advanced across the atrial septum into the LA. Additional curvature may be needed to advance the valve into the mitral valve.
Once satisfactory positioning is achieved, the valve is deployed under rapid ventricular pacing. While the valve may not be perfectly coaxial to the annular plane initially, it often autocorrects during inflation. Slow inflation is essential, and the operator closest to the valve must be prepared to adjust the position. Following deployment, TEE is used to evaluate valve position, leaflet motion, trans-mitral gradients, PVLs, and LVOT gradient. If PVL is present, the valve can be further dilated by injecting additional contrast into the delivery system under fluoroscopy. Completion TEE reassesses PVL after post-balloon dilation.
7. Closure: Completing the Procedure
Iatrogenic septal defects are not routinely closed. However, in the presence of a significant right-to-left inter-atrial shunt or pulmonary hypertension with right ventricular failure, the septostomy can be closed using a percutaneous closure device. The temporary pacing wire, delivery system, and sheaths are then removed from the femoral veins. Protamine is administered, and the Perclose Proglide device in the right femoral vein is secured. Manual compression is applied over the left venous access site for hemostasis, often with a subcutaneous u-stitch. The radial artery sheath is removed, and a TR band (Terumo Interventional Systems, Somerset, NJ, USA) is applied to achieve hemostasis at the radial artery access site.
Transseptal ViV-TMVR: Clinical Outcomes and Considerations
Transseptal ViV-TMVR has emerged as a valuable option for patients with degenerated mitral bioprostheses who are at high risk for repeat surgical mitral valve replacement. While ViV-TMVR is still evolving, recent studies have demonstrated its safety and efficacy in carefully selected patients. In 2017, the FDA approved ViV-TMVR for deteriorated mitral valve prostheses in high-risk patients. Transseptal access has gained prominence due to advancements in steerable delivery catheters. According to the Society of Thoracic Surgeons/American College of Cardiology TVT Registry, transseptal access has surpassed trans-apical access since 2016, with 84.1% of cases performed via the transseptal route. Transseptal access offers several advantages over trans-apical access, including lower rates of conversion to open surgery and lower 30-day cardiovascular mortality. The Valve-in-Valve International Data (VIVD) Registry showed an improvement in left ventricular ejection fraction (LVEF) after transseptal ViV-TMVR in patients with baseline LVEF ≤50% compared to trans-apical access.
Advantages and Disadvantages of Transseptal ViV-TMVR
Transseptal ViV-TMVR offers a safer and effective approach to treat a degenerated bioprosthesis in high-risk patients. It eliminates the need for cardiopulmonary bypass and excising the deteriorated bioprosthesis. It also avoids the trauma to the LV associated with trans-apical access. Furthermore, the femoral vein typically allows for safe introduction of large sheaths and facilitates low-pressure closure with a reduced risk of vascular injury.
A key challenge of ViV-TMVR is iatrogenic LVOT obstruction, which occurs when the transcatheter valve pushes the anterior leaflet of the old bioprosthesis towards the interventricular septum. Techniques like intentional transcatheter laceration of the anterior mitral valve leaflet (LAMPOON) and pre-emptive alcohol septal ablation have been described to mitigate this risk. Achieving coaxial alignment with the mitral annulus can be more challenging with the transseptal approach. Finally, the long-term durability of transcatheter valves in the mitral position remains an area requiring further research.
Conclusion: A Promising Approach
Transseptal ViV-TMVR represents a significant advancement in the treatment of degenerated mitral bioprostheses for high-risk surgical patients. As the technology advances and long-term data accumulates, this approach will likely become even more prevalent in the management of mitral valve disease.
