19.2 Transcatheter Mitral Valve Repair

Transcatheter Mitral Valve Repair

ARRT Cardiac-Interventional Procedures 2.B.5 is transcatheter mitral valve repair. The official name is repair, not replacement. The workhorse the R.T.(CI) must actually run is edge-to-edge repair (MitraClip-class / transcatheter edge-to-edge repair, TEER). Annuloplasty and transcatheter mitral valve replacement (TMVR) sit in the same structural toolkit as awareness — they are not a license to treat every 2.B.5 item as a TAVR-style valve implant. The Focus of Questions still applies: anatomy and pathophysiology, indications, contraindications, imaging, access, ultrasound, equipment, complications, and closure.

Quick Answer: Edge-to-edge (MitraClip-class) TEER treats selected primary (degenerative) and secondary (functional) mitral regurgitation (MR). Access is femoral venous, then transseptal. TEE guides grasping, typically A2-P2. Trade residual MR against iatrogenic mitral stenosis. Named failures: single-leaflet detachment and tamponade. Aftercare antiplatelet or anticoagulation is protocol-based. Know that annuloplasty and TMVR exist; the exam stem is still repair.

Anatomy and pathophysiology

The mitral valve has anterior and posterior leaflets, each with scallops A1–A2–A3 and P1–P2–P3. A2-P2 is the central pair and the usual first clip target. Chordae and papillary muscles tether the leaflets to the LV. Coaptation fails when a leaflet is too long or flail, when a chord ruptures, or when a dilated ventricle pulls the leaflets apart.

Primary (degenerative) MR: the leaflet or chord is the disease — prolapse, flail from chordal rupture, myxomatous degeneration. A discrete jet through a graspable malcoaptation is the TEER sweet spot when there is enough leaflet length to capture.

Secondary (functional) MR: the leaflets may be structurally normal; the ventricle or atrium is dilated, the annulus is large, and leaflets are tethered. Repair here is selected: guideline-directed medical therapy already optimized, anatomy that will allow a grasp, and a ventricle that can benefit. Platform trials (COAPT-class teaching versus less favorable functional-MR cohorts) explain why not every functional jet is a clip. ARRT is not asking for p-values; it is asking you not to clip a jet that is really untreated cardiomyopathy.

Edge-to-edge repair approximates A2 to P2 (Alfieri-style) and creates a double orifice. MR falls if both leaflets are in the clip; orifice area also falls, so a mean mitral gradient can rise. That is the residual MR versus iatrogenic MS tradeoff.

Indications, contraindications, and what is not TEER

Indications (teaching): severe primary MR in a patient who is not a straightforward surgical candidate (or who is selected for TEER by the heart team), and selected secondary MR after GDMT, with anatomy that will allow a grasp. Symptoms include dyspnea, recurrent heart-failure hospitalizations, and pulmonary edema.

Contraindications / stops: active endocarditis, intracardiac thrombus, insufficient leaflet length to grasp, a valve already so stenotic that a clip will create prohibitive MS, a rheumatic valve that needs commissurotomy or surgery rather than a clip, and inability to take the planned antithrombotic regimen. TEE that cannot image the leaflets (impossible airway and no ICE backup) is a practical stop. A functional-MR patient still volume-overloaded on no GDMT is not an automatic clip.

Awareness, not the core 2.B.5 procedure: transcatheter annuloplasty (direct or indirect rings or cinches that shrink the annulus) and TMVR (dedicated transcatheter mitral prostheses, or valve-in-MAC / valve-in-ring / valve-in-valve inside a failed surgical mitral bioprosthesis). TMVR is replacement. If the stem says repair, think TEER. Other TEER platforms (Pascal-class teaching) still do leaflet approximation; they do not change the access-and-TEE story.

Imaging, access, and ultrasound

Imaging. TEE is implant-level guidance: X-plane and 3D for clip-arm orientation, leaflet insertion into the grippers, residual color MR, and the transmitral mean gradient. Fluoroscopy shows the delivery system in the LA; it does not prove both leaflets are in the clip. ICE is adjunctive in some labs, not a default replacement for mitral TEE. Baseline TTE/TEE grades mechanism (primary vs secondary), pulmonary pressures, and LV function so you know whether you are clipping a flail P2 or a tethered functional jet.

Access. Femoral venous is the workhorse (usually right). A large steerable guide goes to the RA. Transseptal puncture is required — this is not the PFO “cross the tunnel” story (18.1). Height and posterior-ness of the puncture are chosen so the clip approaches the mitral coaptation perpendicularly (typically a superior-posterior fossa puncture in mitral TEER teaching). Arterial access is not required for the clip itself unless the operator wants an arterial line. Vascular ultrasound guides the large venous stick and later finds a hematoma on antithrombotics.

Ultrasound in the Focus-of-Questions sense is both that vascular ultrasound and the TEE (or ICE) that watches the grasp. Surface TTE is follow-up, not implant guidance.

Equipment and the grasp

A steerable guide in the LA, a clip delivery system, and one or more clips (nitinol arms with grippers that sandwich leaflet tissue). Newer independent-gripper systems still do the same job: capture both leaflets. Typical first grasp is A2-P2. Additional clips go medial or lateral if residual MR remains and the gradient still allows it. Heparin while left-sided is expected; ACT targets are lab protocol, not an unpublished ARRT second.

The tradeoff: more clips or a tighter grasp → less MR, higher gradient. Lab teaching often worries when the mean mitral gradient climbs into a stenotic range (classic discussion around ~5 mm Hg — lab teaching, not an unpublished ARRT cutoff). Leave moderate residual MR rather than create iatrogenic MS the LV cannot fill through. A pretty color-Doppler frame with a mean gradient the LA cannot live with is not success.

Complications, antithrombotics, and closure

Single-leaflet detachment (single-leaflet device attachment, SLDA): one leaflet slips out; the clip hangs on the other leaflet; MR returns, and the clip can embolize. TEE makes the diagnosis. Management is recapture/snare if the platform allows, another clip if tissue remains, or surgery. Do not call a one-leaflet clip “partial success.”

Tamponade: transseptal or LA-wall perforation — echo now, pericardiocentesis (16.3), surgical backup if the hole is more than a needle puncture. This is why mitral TEER is not a casual table-suite diagnostic.

Other named failures: iatrogenic MS, residual MR, clip embolization, chordal entanglement (the clip grabs chords instead of free leaflet edge), a residual iatrogenic ASD at the transseptal site (usually watched; a large shunt is a different conversation), stroke, and vascular injury from a large venous sheath.

Antithrombotic aftercare is protocol-based, not an unpublished ARRT cocktail. Teaching patterns: antiplatelet therapy (often aspirin, sometimes a short DAPT window) if the patient is in sinus rhythm; continue anticoagulation if the indication is AF. Do not invent a mandatory warfarin-plus-DAPT recipe for every clip, and do not stop indicated AF anticoagulation because “we repaired the valve.”

Closure of the access site is venous hemostasis: figure-of-8 stitch, manual pressure, or a venous closure device. This is not TAVR arterial preclose unless you also placed an arterial sheath.

Table: step / imaging / complication

Worked case

An 82-year-old with a flail P2 (primary MR) and high surgical risk. Femoral venous sheath, TEE-guided transseptal, clip to A2-P2, both leaflets seen in the device, MR falls from severe to mild, mean gradient stays acceptable. If the next frame shows the clip attached only to P2 and A2 is free, that is single-leaflet detachment — not “the MR will remodel.” If instead MR is gone but the mean gradient is high and the LA cannot empty, you have iatrogenic MS — do not add another clip. Sudden hypotension during puncture with a new effusion is tamponade, not oversedation. A dilated-LV functional-MR patient still volume-overloaded on no GDMT is not an automatic clip. If the heart team’s plan is a dedicated mitral prosthesis because the leaflets will not hold a clip, that is TMVR awareness, not the 2.B.5 repair you just ran.

Exam traps

• Treating 2.B.5 as TMVR replacement rather than repair.
• Arterial access as the default clip route.
• Grasping without TEE confirmation that both leaflets are in the device.
• Ignoring iatrogenic MS while chasing zero MR.
• Missing single-leaflet detachment.
• Inventing a single ARRT-mandated antithrombotic cocktail, or stopping indicated AF anticoagulation because a clip was placed.