SamDawkins Consultant Cardiologist

Transcatheter Mitral Valve Replacement (TMVR)

Transcatheter mitral valve replacement (TMVR) is a family of techniques for replacing the mitral valve without open-heart surgery. It is offered to patients with severe mitral regurgitation or mitral stenosis who are not suitable for surgery and where transcatheter repair (Mitral TEER with the Pascal or MitraClip device) is not the right option.

The mitral valve is a more complex target than the aortic valve — it sits in a saddle-shaped, non-calcified annulus, with chords tethered to the heart muscle. There is no single way to anchor a new valve in this position, so several different transcatheter strategies have evolved. Dr Dawkins offers the full range.

When is transcatheter mitral valve replacement considered?

  • Severe mitral regurgitation in patients at increased risk for surgery, where the anatomy or mechanism of the leak does not lend itself to edge-to-edge repair (TEER).
  • Severe mitral stenosis in patients at increased surgical risk — particularly with heavy mitral annular calcification (calcific MS).
  • Failed previous mitral valve surgery — either a degenerated tissue (bioprosthetic) replacement or a failed mitral repair with a residual annuloplasty ring. A re-operation in these patients is often high risk.

Every patient is reviewed in the structural valve multidisciplinary team meeting before a procedure is offered.

The four transcatheter mitral replacement techniques

1. Dedicated TMVR — the SAPIEN M3 system

The SAPIEN M3 (Edwards Lifesciences) is a dedicated transcatheter system designed specifically for native mitral disease. It uses a two-step “dock-then-valve” approach:

  • Step 1 — the dock. A nitinol coil is delivered through the femoral vein and wrapped around the native mitral leaflets and chords. The dock creates a circular landing zone with a defined size and a friction surface for the valve to grip.
  • Step 2 — the valve. A modified SAPIEN balloon-expandable valve is then deployed inside the dock, locking the two together.

The M3 design overcomes the central challenge of native-mitral TMVR — the lack of natural anchoring features — by creating its own. It is available in selected cases through structural valve programmes in the UK; suitability is decided in the structural valve multidisciplinary meeting on a case-by-case basis.

2. Valve-in-Ring (ViR)

Some patients have had previous mitral valve repair with a surgical annuloplasty ring. Years later, the repair can fail — either because the leaflets recur or because the ring becomes a source of stenosis. A repeat operation in these patients is often high risk.

In valve-in-ring, a transcatheter valve (most commonly a SAPIEN) is deployed inside the existing surgical ring. The ring provides the circular landing zone the valve needs to anchor against. Suitability depends on the type of ring (complete vs partial), its size, and the geometry of the surrounding anatomy — all of which are worked out from a planning CT scan.

3. Valve-in-Valve (ViV)

Patients with a previous surgical mitral valve replacement using a tissue (bioprosthetic) valve will, over time, see that valve degenerate — calcifying, narrowing, leaking, or both. A redo sternotomy carries significant risk.

In valve-in-valve, a transcatheter valve is deployed inside the failing surgical bioprosthesis. The metal frame of the surgical valve provides a precise, predictable landing zone. Mitral valve-in-valve is the most established of the transcatheter mitral replacement techniques and is now part of routine care for patients with degenerated surgical mitral bioprostheses.

4. Valve-in-MAC (Mitral Annular Calcification)

Mitral annular calcification (MAC) is heavy calcification of the mitral annulus, increasingly common in elderly patients, those with chronic kidney disease and those with previous radiotherapy. Heavy MAC can cause mitral stenosis, regurgitation or both, and surgery is technically very difficult — the calcium cannot easily be debrided without risking injury to the heart muscle or the circumflex coronary artery.

In valve-in-MAC, a transcatheter valve is anchored within the heavily calcified mitral annulus, using the calcium as the anchor. Of the four techniques, valve-in-MAC is the most demanding — there is a meaningful risk of obstructing the left ventricular outflow tract (LVOT) by displacing the anterior mitral leaflet, and patient selection on planning CT is critical.

How is the procedure performed?

The general flow is similar across all four techniques, with technical differences specific to each.

  • The procedure is carried out under general anaesthetic with transoesophageal echocardiography (TOE) guidance throughout, by a structural imaging cardiologist working alongside the operator.
  • Access is through the femoral vein in the leg. From there a long sheath is steered into the right atrium and across the inter-atrial septum into the left atrium — the same trans-septal approach used for mitral TEER.
  • The new valve (and, for the M3, the dock) is then delivered across the mitral valve and deployed under combined fluoroscopy and TOE guidance.
  • After deployment, the valve is checked carefully on TOE for normal function, absence of paravalvular leak, and that the LVOT remains unobstructed.
  • The femoral access point is closed with a vascular closure device. Patients usually spend one or two nights in hospital.

Who is suitable?

Suitability for transcatheter mitral valve replacement is decided in the structural valve multidisciplinary team meeting. Key factors include:

  • The mechanism and severity of the mitral disease (regurgitation, stenosis, or both)
  • Whether TEER is a feasible alternative (preferred where suitable)
  • The size and geometry of the mitral annulus and left ventricle on planning CT
  • The risk of LVOT obstruction (especially relevant for valve-in-MAC and the M3)
  • The condition of the femoral veins and the inter-atrial septum
  • The patient’s overall surgical risk

A planning cardiac CT is the cornerstone of selection — it provides the measurements that determine whether the technique is feasible, and helps simulate the position and angle of the new valve.

Dr Dawkins’s experience

Dr Dawkins offers the full range of transcatheter mitral valve replacement techniques, including the SAPIEN M3, mitral valve-in-ring, valve-in-valve, and valve-in-MAC. He works closely with cardiac surgeons, imaging cardiologists and anaesthetists in the structural valve MDT, and every transcatheter mitral case is reviewed in detail before a procedure is booked.