Mitral valve annuloplasty is a surgical technique for the repair of leaking mitral valves. Due to various factors, the two leaflets normally involved in sealing the mitral valve to retrograde flow may not coapt properly. Surgical repair typically involves the implantation of a device surrounding the mitral valve, called an annuloplasty device, which pulls the leaflets together to facilitate coaptation and aids to re-establish mitral valve function.

Need

Mitral regurgitation

Mitral regurgitation

Mitral regurgitation , mitral insufficiency or mitral incompetence is a disorder of the heart in which the mitral valve does not close properly when the heart pumps out blood. It is the abnormal leaking of blood from the left ventricle, through the mitral valve, and into the left atrium, when...

 is the most common form of mitral valve dysfunction. Today more than 2.5 million Americans are estimated to be affected by mitral regurgitation. This number is expected to double by the year 2030. Every year, 300,000 people worldwide undergo open heart surgery for mitral valve repair

Mitral valve repair

Mitral valve repair is a cardiac surgery procedure performed by cardiac surgeons to treat stenosis or regurgitation of the mitral valve. The mitral valve is the "inflow valve" for the left side of the heart. Blood flows from the lungs, where it picks up oxygen, through the pulmonary veins, to the...

, 44,000 people in the US alone.

Relevance

Since it was initially established 40 years ago by Professor Alain Carpentier, mitral valve annuloplasty has been continuously improved and is considered the gold standard for the treatment of most etiologies of mitral valve dysfunction today.

Rationale

The goal of mitral valve annuloplasty is to regain mitral valve competence by restoring the physiological form and function of the normal mitral valve apparatus. Under normal conditions the mitral valve undergoes significant dynamic changes in shape and size throughout the cardiac cycle

Cardiac cycle

The cardiac cycle is a term referring to all or any of the events related to the flow or blood pressure that occurs from the beginning of one heartbeat to the beginning of the next. The frequency of the cardiac cycle is described by the heart rate. Each beat of the heart involves five major stages...

. These changes are primarily due to the dynamic motion of the surrounding mitral valve annulus, a collageneous structure which attaches the mitral leaflets and the left atrium to the ostium

Ostium

Ostium may refer to:Anatomy*Ostium of Fallopian tube*Ostium primum or foramen ovale of the developing heart*Ostium maxillare of the maxillary sinus*Ostium of female lepidoptera genitalia...

 of the left ventricle and the aortic root.
Throughout the cardiac cycle, the annulus undergoes a sphincter motion, narrowing down the orifice area during systole

Systole

Systole may refer to:*Systole , a term describing the contraction of the heart*Systolic array, a term used in computer architecture*Systolic geometry, a term used in mathematics...

 to facilitate coaptation of the two leaflets and widens during diastole

Diastole

Diastole is the period of time when the heart fills with blood after systole . Ventricular diastole is the period during which the ventricles are relaxing, while atrial diastole is the period during which the atria are relaxing...

 to allow for easy diastolic filling of the left ventricle. This motion is further enhanced by a pronounced three-dimensional configuration during systole, the characteristic saddle shape. These changes throughout the cycle are believed to be key to optimize leaflet coaptation and to minimize tissue stresses.
The challenge of mitral valve annuloplasty is to improve the diseased and distorted shape of the mitral valve and to reestablish the physiological configuration, while preserving normal annular dynamics. Today, cardiac surgeons can select from a variety of annuloplasty devices, flexible, semi-rigid, or rigid, incomplete or complete, planar or saddle-shaped, adjustable and non-adustable. While the general goal of all devices is the same, namely to increase leaflet coaptation and to support the posterior annulus against dilation, flexible bands are designed to maintain the three-dimensional contour of the native annulus and some of its natural dynamics. The goal of semi-rigid rings is to maintain coaptation and valve integrity during systole, while allowing for good hemodynamics during diastole. Rigid rings are designed to provide rigid support in large dilation and under high-pressure.

Sizing

Annuloplasty devices usually come in different sizes. The surgeon can estimate the dimensions of the patient’s mitral valve and decide on an appropriate ring size. Depending on the disease etiology different approaches are taken. Surgeons can decide to “undersize” the device, “truesize” the device, or “oversize”.

Device classification and regulatory considerations

Annuloplasty devices are classified by the U.S. Food and Drug Administration

Food and Drug Administration

The Food and Drug Administration is an agency of the United States Department of Health and Human Services, one of the United States federal executive departments...

 (FDA) as class II medical device. According to the FDA following issues need to be addressed before annuloplasty rings can be approved for marketing :

Performance testing

• Biocompatibility testing
• Computational structural analysis
• Tensile testing
• Suture pull-out testing
• Sterilization validation
• Biological testing including bioburden and pyrogen testing
• Shelf-life validation

Labeling

• Contraindications
• Potential complications
• Instructions for use
• Specific warnings of potential risks

Commercially available devices

Edwards Life Science

• Carpentier-Edwards Classic Annuloplasty Ring
• Carpentier-Edwards Physio Annuloplasty Ring
• Carpentier-Edwards Physio II Annuloplasty Ring
• Carpentier-McCarthy-Adams IMR ETlogix Annuloplasty Ring
• GeoForm Ring
• Cosgrove-Edwards Annuloplasty System

St. Jude Medical

• St. Jude Medical Séguin Annuloplasty Ring
• St. Jude Medical Tailor Annuloplasty Ring
• St. Jude Medical Tailor Annuloplasty Band
• St. Jude Medical Rigid Saddle Ring
• St. Jude Medical Attune Annuloplasty Ring

Medtronic

• Profile 3D Ring
• CG Future Ring and Band System
• Duran AnCore Ring and Band System
• Simulus Adjustable Annuloplasty System
• Simulus Flexible Annuloplasty System
• Simulus Semi-Rigid Annuloplasty System

Minimally invasive annuloplasty

New technologies that allow for minimally invasive surgery have also begun to change mitral valve surgery. A number of devices and techniques have been developed that do not necessitate open-heart surgery for the repair of the mitral valve. Following is a list of minimally invasive annuloplasty devices or related :

Coronary Sinus Delivery

• Cardiac Dimensions
• Mitralign
• Monarc (Edwards LifeSciences)
• Viaco

Other

• Accucinch
• ExTensia
• MitralSolution