Why is Transcatheter Aortic Valve Implantation (TAVI) needed?
Transcatheter Aortic Valve Implantation (TAVI) is used to treat severe Aortic Stenosis, a condition in which the aortic valve becomes narrowed, obstructing the outflow of blood from the heart and thereby requiring the heart to work harder to pump blood around the body.
TAVI is a procedure performed using the Edwards Sapien Transcatheter Heart Valve (THV), an artificial heart valve designed to be inserted into your heart so that it holds open and replaces your diseased aortic valve. It consists of a metal stent (made of steel or cobalt-chromium) which secures the device in its intended position inside your own valve, and valve leaflets (made of biological material derived from cows) to direct the flow of blood out of your heart.
TAVI now offers effective treatment to patients who are at high risk for conventional open heart surgery. It is also intended to prevent further damage to the heart from Aortic Stenosis and to prolong life, which medical therapy cannot do.
What can I expect before the procedure?
Before the procedure, you will undergo routine investigations to evaluate whether TAVI is possible and which of the two techniques for TAVI (Transfemoral or Transapical route) is most appropriate for you. The investigations will also and to identify any other considerations that need to be addressed for your treatment.
The investigations include:
A physical examination
Whether you are selected to undergo the transfemoral or the transapical approach, this procedure will be performed under general anesthesia. As the heart is not opened to expose the aortic valve, fluoroscopy (X-rays) and transesophageal echocardiography (ultrasound) are used to visualize the heart and THV, and to guide the insertion of the THV. The duration of X-ray exposure that you will receive will normally be not more than 30 minutes, the normal length of time it takes for a coronary artery procedure in the cardiac catheterization laboratory.
The transfemoral device is designed to be implanted through the blood vessel (femoral artery) in your leg. Due to the size of the catheter (hollow tube) being placed in your artery for this approach, your doctors will evaluate the angiograms and/or CT scans to ensure your blood vessels are big enough for this device. Prior to implantation, the THV is “crimped” (carefully compressed to a size that fits inside your femoral artery) using a specifically designed crimping device. The crimped THV is mounted onto a balloon delivery catheter, a special device which is used to carry the THV up to the heart and directly into your aortic valve. The valve is then expanded using a balloon to fit inside your stenotic aortic valve, holding your own valve open permanently. Once the valve is in position and the delivery system is removed from your femoral artery, the artery is closed using a special suture device designed for this purpose. After the procedure, you will be transferred to the Coronary Care Unit (CCU).
The transapical approach is used for patients whose arteries are too small or too diseased for the transfemoral approach.
The delivery system for this approach is designed for THV implantation through the tip (apex) of your heart, which is reached through a small incision made between the ribs just below the left nipple. The crimped THV and delivery system is inserted through the apex of your heart directly into your stenotic aortic valve. The valve is then expanded using a balloon to fit across your stenotic aortic valve, holding it open permanently. After the procedure you will be transferred to the Cardiothoracic Intensive Care Unit (CTICU).
What happens after the procedure?
After the TAVI procedure, you will be transferred to either the CCU ward or the CTICU ward for close monitoring. When you are first transferred, you may be under sedation and on ventilatory support. Over the course of the next 24 hours, you will be awakened from the sedation and allowed to breathe on your own with the ventilation tube removed. You will remain in the CCU or CTICU ward until your doctor feels that you can be transferred to a regular hospital ward, where you will continue to be monitored until your discharge from the hospital, usually within 5 – 7 days.
You will be given blood thinning medications such as aspirin and clopidogrel (Plavix). You should continue taking these or other blood thinners for 6 months after the procedure and aspirin for life (as recommended for routine stenting of coronary blood vessels and any replacement heart valve). The following routine checks will be completed while you are in hospital:
A physical examination
Daily electrocardiogram (ECG)
Standard blood tests
Transthoracic echocardiogram (TTE)
Thereafter, you will be required to see your doctor in the clinic after 30 days, 6 months, 12 months, and then once a year. The routine checks such as echocardiography are repeated at your first and subsequent outpatient follow-ups.
What are the potential risks/complications of the procedure?
Like any other kind of operations, there are risks associated with this procedure. However, the long-term risk to your life and your quality of life may be higher if severe Aortic Stenosis is not treated.
The risks of TAVI include the following:
Death (1 – 10%)
Heart or blood vessel injury, such as perforation or damage of blood vessels, heart muscle valve structures that may require emergency surgery (1 – 10%)