TRANSCATHETER AORTIC VALVE REPLACEMENT (TAVR): AN OPEN HEART ALTERNATIVE

Transcatheter aortic valve replacement (TAVR) is an advanced minimally invasive procedure done to replace a diseased aortic valve.

Traditionally, aortic valve stenosis has been treated by open heart surgery, which is largely invasive and carries moderate surgical risks. Before TAVR, many patients were denied surgery since they were deemed unfit.

The introduction of TAVR allowed cardiologists to offer aortic valve replacement to patients with high operative risk. No thoracotomy (middle chest incision). No need to cut the vessels and heart open. All of the procedure is done through a catheter that travels the blood vessels.

If you have aortic valve stenosis and are considering valve replacement, keep reading to know more about this open heart alternative!

What is Aortic Stenosis?

To understand how TAVR works, you first need to understand some heart anatomy.

The heart has 4 main valves:

• Pulmonary valve
• Mitral valve
• Aortic valve
• Tricuspid valves

These valves separate the chambers of the heart and prevent the backflow of blood. The aortic valve is arguably the most important valve of the heart. It sits at the beginning of the major blood vessel that comes out of the heart to distribute blood to the body - called the aorta.

Normally, this valve opens freely and closes firmly as the heart pumps blood during each contraction. Aortic stenosis is when this valve becomes narrow (usually happens with aging) and hence does not allow enough blood to pass through. The symptoms of aortic stenosis include shortness of breath, chest pain, syncope, and loss of exercise ability.

What is TAVR?

Transcatheter aortic valve replacement (TAVR) is also sometimes called Transcatheter aortic valve implantation (TAVI).

As the name implies, the procedure is done completely through the blood vessels without opening up the thoracic cavity or cutting the heart open.

The new biological prosthetic aortic valve is implanted inside the old diseased valve (valve-in-valve). A biological prosthetic valve is made of pig or cow tissue.

This procedure is done by an interventional cardiologist.

TAVR has some excellent advantages:

• It is less invasive and hence incurs fewer intraoperative risks
• It is suitable for patients with high surgical risk
• It can be done under sedation (without general anesthesia)
• The benefit is comparable to that of surgical aortic valve replacement

These are the reasons why cardiologists are excited about this fairly new treatment of aortic valve stenosis.

Who is a candidate for TAVR?

Previously, TAVI was indicated only in patients who are not candidates for surgery (aka high-risk patients with lung disease or other serious health problems).

As of 2019, however, the FDA approved TAVR also for low-risk patients. So, you’re a candidate for TAVR if you have symptomatic aortic valve stenosis, regardless of your surgical risk.

In general, the medical community seems to be heading toward normalizing TAVR and making it the treatment of choice for aortic stenosis, regardless of the patient’s surgical risk. This means that, in the future, TAVI might be the first choice treatment for all patients with aortic valve stenosis.

More and more studies are being done in the low-surgical risk population to support such a move toward a less invasive procedure.

How does TAVR compare to Surgical Aortic Valve Replacement (SAVR)?

One major meta-analysis done in 2019 compared TAVR and SAVR in terms of benefits and risks. The study involved both low-risk and high-risk patients. This is what the authors concluded:

• Patients who had TAVR were more likely to be alive at 2 years after the procedure (regardless of the cause of death in others)
• Patients who had TAVR had less risk of stroke
• Patients who had SAVR had less risk of blood vessel complications
• Patients who had SAVR were less likely to require a pacemaker

So, although TAVR seems to generally be superior to open-heart surgery, more studies are needed to show that these added benefits outweigh any added risks.

What are the risks of TAVR?

Transcatheter aortic valve replacement is thought to be less invasive, and hence less risky than surgical valve replacement. In fact, this is why it is indicated in patients with high surgical risks.  Nevertheless, it still carries some risks. Some of the reported complications with TAVI include:

• Bleeding
• Stroke
• Heart rhythm abnormalities
• Requiring a pacemaker
• Blood vessel injury

These complications are not common, however, you should discuss their risk in more detail with your cardiologist before you make a decision.

How is TAVR performed?

The procedure is done by an interventional radiologist at a hospital’s specialized unit.

TAVR can be done under general anesthesia or with sedation. General anesthesia means that you will be put to deep sleep and intubated (for breathing). With sedation, you will not feel pain and you might fall asleep, but can be easily woken up and won’t need assistance to breathe.

Next, your cardiologist will insert a catheter through a major blood vessel and advance it to reach your heart. There are four sites where your doctor might insert the catheter through:

• Transcarotid: Through the carotid artery in your neck
• Subclavian: Through the subclavian artery under your collar bone
• Transfemoral: Through your femoral artery in your groin area
• Transapical: Directly into the heart, through the space between your rib bones

The catheter is inserted into your vessel and then your doctor will push it inside until it reaches the aortic valve. During this maneuver, your doctor will be visually observing the catheter on a screen connected to an X-ray machine directed at your body. They will inject contrast material to better visualize the vessels.

Once they reach the aortic valve, a balloon will be blown to widen the diseased valve.

Then, the prosthetic valve is advanced along the catheter and fixed into place inside the old valve.

The catheter is then pulled out and you will be woken up.

Recovery After TAVR

After TAVR, you will be taken to the intensive care unit (ICU) to spend the night for monitoring. After that, you will spend 2-3 days on the regular floor before you are discharged.

You can generally regain your strength within days or weeks after a TAVI. In comparison, patients who get open heart surgery might need 2-3 months to fully recover.

You will be prescribed aspirin or another antiplatelet medication that you should take indefinitely after TAVR.

Since you will have a prosthetic heart valve, you will be instructed to maintain good mouth hygiene and to inform your dentist before any procedure. Dental procedures can push bacteria into the blood, which might cause a valve infection.

Outlook

Transcatheter valve replacement is an advanced and promising procedure for patients with aortic valve stenosis.

Doctors are continuously exploring TAVI to understand its risks and benefits better as compared to surgical valve replacement. Medical device companies are also working hard on designing the perfect prosthetic valve for TAVR to make the procedure even more successful.

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Sources:

• https://www.fda.gov/news-events/press-announcements/fda-expands-indication-several-transcatheter-heart-valves-patients-low-risk-death-or-major
• https://www.uofmhealth.org/conditions-treatments/frequently-asked-questions-tavr#
• https://www.practiceupdate.com/content/tavi-vs-savr-symptomatic-for-severe-aortic-stenosis/82978
• https://www.nhlbi.nih.gov/health-topics/tavr
• https://www.medtronic.com/us-en/patients/treatments-therapies/transcatheter-aortic-valve-replacement.html
• https://www.heart.org/en/health-topics/heart-valve-problems-and-disease/understanding-your-heart-valve-treatment-options/what-is-tavr

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