Annuloplasty Ring

Introduction:

As we age, the valves in our hearts may become damaged due to infection or heart disease. Some issues in the hear are a result of congenital birth defects. The affected valve leaflets can grow and form scar tissue, or grow thin and weak leading to a valve that does not function properly.[1] Over time the damaged valve may not open and close correctly causing blood to leak backward into the valve. The damaged valve also makes the heart work harder to pump blood throughout the body. [1]

Anterior cut view of heart. Healthy and damaged mitral valve shown.

Symptoms of a Damaged Heart Valve:

• Becoming tired with small activities
• Irregular heartbeat
• Shortness of breath
• Dizziness
• Fainting

An annuloplasty is a procedure done to tighten or to strengthen the ring, or annulus, around a valve in the heart that is damaged. [1] The damaged valve leaflets grow thicker and more brittle from scar tissue or calcium deposits. This causes the leaflets to become thin and weak. This procedure is typically performed using open-heart surgery. During this procedure, a surgeon measures the size of the existing ring and a band is sewn onto the ring around the valve by tucking in the leaflets. [1] In doing so, platelets tend to stick to the artificial material of the annuloplasty ring cause the receiver to attend anti-coagulation therapy for the rest of their life in order to prevent blood clots. 

Implantation of an Annuloplasty Ring

A mitral valve repair offers excellent results in the case of degenerative heart disease, both in immediate and long-term scenarios. [1] This procedure is performed with low surgical risk and a high success rate. The technique used during the implantation of the annuloplasty ring is crucial and has been observed to be the leading role of success. The correct technique ensures the stabilization of the annulus and the restoration of the physiological systolic relationships.  However, for these things to occur, placement of every suture, proper ring selection, and proper ring sizing must be done correctly. [2]

Alternative Treatments:

• A commissurotomy 
• Implanting a tissue valve
• Implanting a mechanical valve

If the damaged heart valve is tight, or suffering from aortic stenosis, then a commissurotomy can be performed. This procedure cuts the valve leaflets to loosen the valve enough for blood to pass through easily. [2] However, depending on the extent of the valve disease, the valve may need to be completely repaired or even replaced. In this case, an annuloplasty ring can not be used. Instead, a surgeon might replace the damaged valve with a bio-prosthetic, tissue valve, or a mechanical valve. [3] If a tissue valve is used, the valves are retrieved from animals such as cows or pigs. Mechanical valves are made from plastics or metals.

Types of Annuloplasty Rings:

Annuloplasty ring manufacturers:

• Medtronic
• LivaNova
• Edwards Lifesciences 
• St. Jude Medical.

Left: Medtronic (Braided Polyester) Right: LivaNova (Knitted Silicone and Polyester)

The rings are composed of a core and a fabric. The core is typically a metal such as titanium, although silicone is sometimes used too, which determines the rigidity of the ring: flexible, semi-rigid, or rigid. [4] The core is covered using fabric, usually composed of polyester. The fabric structures used for the polyester vary. Traditionally, the polyester is knitted or braided because these structures allow control over the porosity of the fabric cover. Porosity control enables tissue growth and allows for more flexibility to accommodate dynamic valve function. [4]

Implantation of an Annuloplasty Ring:

An Annuloplasty is a procedure that helps tightens and improves the ring around a valve that is present in the heart. The three main reasons for proceeding with this type of intensive surgery include: reshaping the valve by removing the excess tissue that is around the valve, adding support to the valve itself by adding more tissue, or by attaching a sewing band or sometimes a ring around the outside of the valve.

In the video below,  the procedure of an annuloplasty on the mitral valve that is left of the atrium and left of the ventricle is shown.

There are some critical steps that are involved during the procedure. The different techniques for the placement of suture which can help stop future perivascular leaks and folds on the annular edge. Sizing is also an important factor that must be considered when correcting the ring that is around the heart valve. Once sizing the heart valve for the new annuloplasty ring its important to remake the sizing after placing the sutures. 

 

Disadvantages and Advantages of Annuloplasty Ring:

Some of the advantages of the Annuloplasty ring includes: new saddle-like design that can help with the flexible properties within the medical device, this structure can help preserve that life of the annuloplasty ring by five years inside of the patient before a repair is needed. Another advantage of an Annuloplasty ring is the new material that is available (ex: knitted silicone and polyester) can help with the imitate the original heart valve by having similar shapes and sizes available. Some of the disadvantages of the annuloplasty ring is that the new flexible band that is popular can cause potential risk in the future like, pannus formation (abnormal layer of fibrovascular tissue) and even calcification. The Annuloplasty Ring would soon become rigid.

The picture below shows calcification of the mitral annular

 

Studies involving Testing of Annuloplasty Rings:

One of the most known about procedure that pertains to the Annuloplasty Rings is in-vivo.  The reason for this trial is to prove the concept of surgical implantation of a personalized bio-compatible mitral annuloplasty ring. Six healthy pigs were placed under anesthesia. Based on the different sizes of the pig’s mitral annulus, a customized solid ring with integrated suturing holes was the design and manufactured from a biocompatible titanium alloy. 50 % of the personalized mitral annuloplasty ring was perfectly matched. The results proved that it is reasonable to create annuloplasty rings.

Another study on Annuloplasty rings is their morphology. Flexible, semirigid, and rigid were compared from clinical studies and animal studies on their effectiveness. The results from the study revealed that ring morphology and consistency do not seem to play a major clinical role in mitral valve repair based on the present literature. This means that until demonstrated otherwise, surgeons should choose their ring upon their judgment, tailored to specific patient needs. [5]

Business Strategy:

According to the WHO, cardiovascular diseases is the leading cause of death worldwide, which claims around 17.7 million lives every year and the Mayo Clinic reported that there are more than 200,000 cases of Mitral valve regurgitation every year. The demand for cardiovascular products will not decline anytime in the foreseeable future.

Above: Line chart on the interest over time of worldwide Google searches from 2004-present of heart valve disease and annuloplasty ring.

This graph shows a line chart plotting Google searches for heart valve disease in blue and annuloplasty ring in red. The numbers represent search interest relative to the highest point on the chart for the given region and time. A value of 100 is the peak popularity for the term. A value of 50 means that the term is half as popular. A score of 0 means there was not enough data for this term. [6] A graph interpretation would suggest that worldwide Google searches for heart valve disease is increasing while the interest in annuloplasty rings has stayed consistent for the past eleven years. 

The end-users of annuloplasty rings are the hospitals and surgeons that use the annuloplasty rings during surgeries. Websites and advertisements market annuloplasty rings towards doctors and healthcare officials with specifications and healthcare terminology. Surgeons select annuloplasty rings based on their judgment tailored towards the patients’ needs. Therefore, the best way to sell annuloplasty rings is to get feedback on the product from surgeons and healthcare officials to make improvements. There is a market for more personalized annuloplasty rings for patients with severe mitral regurgitation. In a study, surgeons constructed personalized rings in the operating room to custom-fit individual mitral annulus shape and size. Conclusions showed that the precise fit of the PR to the mitral annulus better preserves valve area and sphincter function of the mitral annulus, prevents SAM, and provides excellent short and long-term results.  [7]

Resources:

1. “Mitral Valve Repair and Mitral Valve Replacement.” Mayo Clinic, Mayo Foundation for Medical Education and Research, 17 May 2019, http://www.mayoclinic.org/tests-procedures/annuloplasty/pyc-20384965.
2. “Cardiovascular.” SecantGroup, secant.com/capabilities/research-and-development/medical-applications/cardiovascular.
3. Sesupport, Sesupport. “Mitral Valve Surgery.” Mitral Valve Surgery, 25 May 2017, http://www.hopkinsmedicine.org/heart_vascular_institute/conditions_treatments/treatments/valve_mitral.html.
4. Medtronic. “Mitral Valve Repair Surgery – What Is It.” Medtronic, http://www.medtronic.com/us-en/patients/treatments-therapies/surgical-heart-valve-repair-and-replacement/mitral-valve-repair/what-is-it.html.
5. Khamooshian A, et al. “Mitral valve annuloplasty rings: review of literature and comparison of functional outcome and ventricular dimensions.” Innovations, vol. 9, no. 6, Dec. 2014. Pubmed, doi:https://www.ncbi.nlm.nih.gov/pubmed/25469460.
6.  “Google Trends.” Google, https://trends.google.com/trends/explore?date=all&geo=US&q=Heart%20valve%20disease,annuloplasty%20ring

7. Boudoulas, H. et al. “Mitral valve repair: moving towards a personalized ring.” J Cardiothorac Surgery, vol. 14, no. 108, 13 June 2019, doi:https://www.ncbi.nlm.nih.gov/pubmed/31196216.