Transcatheter Aortic Valve Replacement / Implantation (TAVR / TAVI)

Introduction

Transcatheter aortic valve implantation/replacement, referred to as TAVI/TAVR, is a minimally invasive cardiac procedure to replace a faulty valve in the aorta that either prevents it from opening completely, or causes a severe leak back. In TAVI/TAVR, the interventional cardiologist implants an artificial (or human-made) valve using a long, thin, flexible tube called the catheter. The procedure does not require open-heart surgery as the catheter is inserted through an artery, usually from the groin (femoral artery). 

Transcatheter aortic valve implantation/replacement (TAVI/TAVR), the procedure uses minimal incisions at the groin compared to open-heart valve surgery, making it a viable therapeutic option for people with severe aortic valve disease (Aortic stenosis or Regurgitation). 

What is an Aortic Valve? 

The heart has four valves, and the aortic valve is one of them. It is located between the left lower heart chamber (ventricle) and the aorta, the body’s main artery. This aortic valve acts as a doorway between the heart and the aorta. The aortic valve opens when the heart contracts and pumps blood across it into the aorta. When open, this valve sends oxygen-rich blood from the heart to the rest of the body. The valve then closes to prevent blood from leaking into the ventricle. The valve generally has three flaps or leaflets that regulate the direction of the blood flow. The flaps open when the ventricle contracts and close on relaxation of the ventricle.

Aortic stenosis is a condition where the aortic valve becomes narrow and stiff. This condition may cause the heart to work too hard to pump blood through the small valve opening to the rest of your body. Hence, it may obstruct blood flow and can lead to chest pain, fainting, and fatigue, thereby increasing the risk of heart failure. For eligible patients, TAVI/TAVR offers a safer alternative to open heart surgery to replace the valve.

Causes of Aortic Stenosis

Some of the common causes of aortic stenosis include

• Age-related calcification - an increase in the calcium deposition on the valve with age is the most common cause
• Congenital defect - Malformed or abnormal valve since birth, Bicuspid or Unicuspid aortic valve
• Rheumatic Heart Disease - Leading to inflammation of the valve and subsequent damage
• Radiation treatment - Previous radiation to the chest can cause scar tissue
• History of endocarditis - an infection of the inner lining of the heart chambers and valves exacerbates damage
• Hypertension - Chronic high blood pressure adds strain on the valves, weakening their function

As the aortic stenosis gets worse, there is severe shortness of breath, chest tightness, dizziness, and heart palpitations. Diagnostic tests like echocardiograms and cardiac catheterization help determine the severity of the stenosis.

How does TAVI/TAVR Work?

TAVR is similar to placing a stent. It involves using a catheter to place a replacement valve in place of the narrowed aortic valve. TAVI/TAVR is performed by a specialist team that includes interventional cardiologists and cardiac surgeons. The key steps of the procedure are as follows:

• The cardiologist will select an artery (usually the femoral) and get an arterial access using a needle.
• Then, they insert a catheter through it and guide it up to the heart through this artery.
• The cardiologist will use medical imaging devices (Fluoroscopy) to navigate the catheter carrying the compressed replacement valve across the old valve.
• Once correctly positioned, the replacement valve is placed firmly by expanding an attached balloon to push the leaflets outward or by unsheathing the valve in case of a self-expandable valve
• The positioning and working of the new valve are assessed and confirmed using an echocardiogram (ECHO).
• The cardiologist then carefully withdraws the catheter and closes the incision.

The procedure lasts around 1–2 hours. The replacement valve starts functioning immediately to restore normal blood flow from the heart. Once the new valve is expanded, it displaces the old valve leaflets out of the way, and the tissue in the replacement valve controls the blood flow.

Who are the perfect candidates for TAVI/TAVR?

TAVI/TAVR may be an option for patients with severe symptomatic aortic stenosis who are considered at low, intermediate, high, or extreme surgical risk for open heart valve surgery. Age, comorbidities, and reduced heart function can increase the risk. Patients who may benefit from TAVR include:

• Elderly patients whose age or frailty make surgery high-risk
• Patients with comorbid conditions like lung disease, kidney disease, or diabetes
• People with prior cardiac surgeries or chest radiation exposure
• Patients with reduced heart function or chronic obstructive pulmonary disorder
• People with certain malformed valves
• Elderly patients without any other risk factors

What is the Recovery Like After a TAVI/TAVR? 

• The patient is required to stay in the hospital for 2–3 days if there are no complications.
• The place of the incision will be sore initially, but it will heal quickly.
• The cardiologist may suggest a temporary pacemaker if the heart rate is unstable.
• Medications to prevent blood clotting will be prescribed.
• Heavy, strenuous activity should be avoided, while the patient can do low-level activities after going home.
• Follow-up visits are recommended to assess valve performance and heart function.

Potential benefits of TAVI/TAVR compared to open heart surgery

• Less invasive procedure with faster recovery
• Avoids risks associated with chest incision and cardiopulmonary bypass
• Reduced risk of operative mortality and stroke
• Decreased length of hospital stay
• Quicker return to normal daily activities after the procedure
• High rate of reducing symptoms and improving heart function

Some risks and considerations:

• Risk of major vascular complications from a large catheter
• Possibility of a paravalvular leak if the valve does not fully seal with tissue
• If the heart’s electrical conduction is disrupted, which affects the heart rhythm, it may require a permanent pacemaker
• Risk of stroke, especially in the first few days after the procedure
• Potential for valve dislodgement or misalignment if not placed properly
• Endocarditis prevention with antibiotics is needed for some procedures

FAQS

1. What is the TAVI/TAVR valve made of?

The valves are usually sourced from animal heart tissue (cow or pig) and are mounted on a stent frame made up from an alloy of either nickel and titanium (Nitinol) or cobalt and chromium. 

2. How successful is TAVI/TAVR at treating aortic stenosis?

TAVI/TAVR is very effective, with over 99% of patients seeing reduced symptoms and improved valve functioning. Long-term outcomes have been very favorable for TAVI.

3. Is TAVI/TAVR permanent or temporary?

The new valve implanted via TAVI/TAVR is long-term. Regular follow-up is needed to confirm it continues to function well.

4. When can I start exercising after the TAVR procedure?

Light exercises of 15–20 minutes are recommended after 1–2 weeks of the procedure. However, avoid strenuous activities, like lifting heavy objects, swimming, or playing sports, for at least 4–6 weeks after the procedure.