Mitral valve replacement refers to the substitution of the mitral valve either by a mechanical valve or bioprosthesis.

Indications

Mitral valve replacement has been superseded by mitral valve repair in most situations of mitral valve dysfunction ^1-3. Further existing indications of operative mitral valve replacement include the following ^1-3:

• irreparable mitral valve pathology

• expected poor durability outcomes with mitral valve repair

  • significant mitral annular calcification

  • severe dystrophic, inflammatory or infective leaflet alterations

  • subvalvular thickening or fusion

  • progressive cardiomyopathy with mitral annular dilation

  • low comorbidity

• rheumatic valve disease with mitral stenosis (in situations where percutaneous mitral commissurotomy is contraindicated or unavailable)

Indications regarding mechanical and bioprosthetic valves are subject to the desired impact on cardiac function and the perioperative and long-term risks involved. Generally, mechanical valves are preferred in structural valve failure and younger patients who have no contraindications to long-term anticoagulation or already receive it for another reason ^1,2. Bioprosthetic valves are preferred in situations where higher doses of anticoagulation is an issue, in older age groups or when future interventions are considered low risk or after mechanical valve thrombosis despite good anticoagulation ^1,2.

Contraindications

Contraindications of mitral valve replacement include the following conditions ^1-3:

• mitral valvular pathologies suitable to mitral valve repair or transcatheter mitral valve replacement

• contraindications to respective therapeutic anticoagulation levels for mechanical valves

Prosthesis design

The following prosthetic mitral valve implants have been in use:

• mechanical

  • tilting disc

  • bi-leaflet disc

  • cage ball valve (no longer implanted)

• biological

  • stented porcine bioprostheses

  • pericardial bovine prostesis

Procedure

A rough overview of the surgical procedure includes the following steps ¹:

• median sternotomy or by endoscopic and robotic approaches

• cardiopulmonary bypass

• transseptal incision via access through the Sondergaard groove or transarterial oblique approach

• excision of the native valve and implantation of the prosthesis with preservation or reinforcement of the native subvalvular structures

• fixation preferably with non-everting stitches

Complications

Complications of mitral valve replacement include the following ^1,2:

• left ventricular rupture (annulus, papillary muscles, midventricular zone)

• thromboembolism including valve thrombosis (most common)

• anticoagulant-related haemorrhage

• infective endocarditis (3-6% within the 5 years)

• paravalvular leak (rare in about 1.5%) and haemolysis

• annular pannus formation with leaflet dysfunction in mechanical valves

• structural valve degeneration in bioprosthetic valves

• regurgitation

• progressive stenosis

Radiographic features

Plain radiograph

In particular mechanical valves might show up on chest x-ray, which might aid in the identification.

Echocardiography

Echocardiography is considered is the imaging modality of choice for follow-up of mitral valve replacement. In the first five years after implantation it is recommended annually for evaluation and detection of the following complications ¹:

• structural valve degeneration

• mitral regurgitation

• mitral stenosis with leaflet calcification and stiffening

• paravalvular leak

Radiology report

The radiological report should include a description of the following features:

• mitral valve prosthesis and type

• left ventricular volumes and measurements

• complications (if present)

  • structural valve degeneration

  • mitral regurgitation

  • mitral stenosis with leaflet calcification and stiffening

  • paravalvular leak

Outcomes

Perioperative mortality rates of isolated mitral valve replacement are estimated in the 4-7% range. Reported 10-year survival is not significantly different between mechanical and bioprosthesis and in the range between 50% and 60% ¹.

Advantages

An advantage of mitral valve replacement is that it is also feasible in complex situations, where mitral valve repair is no longer possible.

Disadvantages

Disadvantages of mitral valve replacement over mitral valve repair include the following ¹:

• higher operative mortality

• replacement-related complications 

• lower mid and long-term survival

See also

• prosthetic heart valve

• mitral valve repair

• transcatheter mitral valve intervention