TAVI Procedure: CT Planning, Valve Types and Access Routes

A TAVI procedure is decided by its planning. A contrast CT scan of the aortic root and the arteries is analysed in detail to size the valve, choose between a balloon-expandable and a self-expanding design, check the risk of blocking a coronary artery or rupturing the annulus, and pick the access route. The implant itself then takes about 20 to 30 minutes.

For Dr. Subhash Chandra, Chairman - Interventional Cardiology - Cardiology & Structural Heart Disease, BLK-Max Super Speciality Hospital, New Delhi, India, this is the central lesson of transcatheter aortic valve implantation (TAVI), also called transcatheter aortic valve replacement (TAVR). In his words, doing the TAVI is not a great feat and does not need very high-level skills; the whole energy should go into planning before the procedure begins. This article follows that sequence: the CT analysis, the valve types, the step-by-step implant, the access routes when the groin is unsuitable, the complications and how they are prevented, and the extension of the same technique to failed surgical valves and the mitral position. Why aortic stenosis needs treatment, and when, is covered in the complete guide to TAVI for aortic stenosis.

Why the CT scan is the most important step before TAVI

The CT scan is the most important step because it decides the valve size, the valve type, the coronary and annular risks and the access route. A thorough CT scan analysis is required before any TAVI is attempted. Unlike an echocardiogram, a contrast CT scan gives a three-dimensional map of the aortic root and of the entire route from the groin to the heart. Dedicated three-dimensional reconstruction software lets the operator measure the anatomy precisely and simulate the implant before the patient reaches the catheterisation laboratory.

The CT analysis answers five questions:

1. Annulus size. The annulus, the ring at the base of the aortic root where the valve sits, is measured along with the subannular area, the supra-annular area and the left ventricular outflow tract (LVOT), the channel just below the valve. These dimensions determine the valve size. In Dr. Chandra's description, the valve is typically oversized by 10 to 20% relative to the annulus so that it anchors securely.
2. Coronary heights. The heights of the left and right coronary artery openings above the annulus are measured. If an opening sits low, the displaced native leaflet can be pushed over it when the new valve expands, blocking the artery. Coronary occlusion, he stressed, can be catastrophic.
3. Calcium. The amount and position of calcium on the valve and in the outflow tract are mapped, because heavy calcium can lead to annular rupture when the valve is expanded.
4. Valve morphology. CT confirms whether the valve has three leaflets or is bicuspid (two leaflets), which changes how the valve behaves when expanded.
5. Access vessels. The femoral and iliac arteries are assessed along their length for diameter, calcium and stenosis. Dr. Chandra's rule is that a femoral artery narrower than 5 mm is not suitable for pushing the valve through the groin.

Planning extends beyond the valve. On the same scan, the team anticipates what it will face in terms of coronary occlusion, groin complications and stroke. The CT can be done locally, in the patient's own country, and sent to the implanting centre for this analysis, which allows a TAVI to be planned before the patient travels.

Types of TAVI valves: balloon-expandable and self-expanding

Two kinds of valve are available for TAVI, and the choice depends on the anatomy the CT reveals.

Balloon-expandable valves

In a balloon-expandable valve, the valve is crimped, like a stent, on top of a balloon. Once it sits across the annulus, the balloon is inflated from outside the body under rapid ventricular pacing (a pacing wire drives the heart at a very fast rate for a few seconds so that it barely ejects blood and the valve is not pushed out of position). The valve seats itself in the annulus and starts functioning at once; the balloon is withdrawn and the valve stays in place.

Dr. Chandra named two balloon-expandable valves:

• the SAPIEN valve, from Edwards Lifesciences in the United States
• the Myval, manufactured by Meril

Meril is an Indian company, and the Myval is widely used around the world. Dr. Chandra put its price at almost 50% of the SAPIEN's, an advantage he highlighted for countries such as Ethiopia. He added that the Myval has been compared with other valves and has performed well across many countries. In the LANDMARK randomised trial, published in 2024, the Myval was non-inferior to the contemporary SAPIEN and Evolut valves at 30 days.

Self-expanding valves

A self-expanding valve sits inside a metal frame that springs open on its own as the delivery sheath is withdrawn, without a balloon. An outer skirt around the frame seals the gap between the valve and the native annulus to prevent paravalvular leak, a leak of blood around rather than through the new valve. Dr. Chandra counted at least five or six iterations of self-expanding valve, from different companies, including Abbott and Medtronic.

The TAVI procedure, step by step

A standard transfemoral TAVI moves through six steps: assessment, imaging of the aortic root, pre-dilatation where needed, delivery of the valve through the groin, deployment under rapid pacing and confirmation on angiography. Dr. Chandra illustrated the standard transfemoral procedure with the case of a man in his early seventies with pulmonary fibrosis, which made him unsuitable for open heart surgery or a heart-lung machine. He had severe calcific aortic stenosis with a valve area of 0.5 cm², preserved left ventricular function and a high STS surgical risk score (the Society of Thoracic Surgeons estimate of the risk of dying after surgery).

His CT showed a type 1 bicuspid valve, which, Dr. Chandra acknowledged, is perhaps not the most suitable anatomy for TAVI. But surgery carried a very high risk and his femoral arteries were good, so TAVI was chosen. The sequence was:

1. Assessment. ECG, echocardiography and the CT analysis described above, followed by matching the measurements to the valve size best suited to his annulus.
2. Imaging the root. An aortogram (an X-ray dye injection into the aorta) was taken in the three-cusp view, which lines up the three valve cusps on the screen for accurate positioning.
3. Pre-dilatation. The valve was crossed with a wire and opened first with a balloon, which a heavily calcified bicuspid valve needs.
4. Delivery. A Myval was advanced through the groin and positioned across the native valve.
5. Deployment. Under very rapid pacing, the balloon was inflated. The diseased valve was pushed to the side and the new valve started functioning.
6. Confirmation. A final angiogram showed blood flowing freely into the coronary arteries through the open cells of the valve frame.

The patient went home with a zero gradient across the valve and continues to attend follow-up. Dr. Chandra expects the valve to last him at least 10 to 15 years, after which another TAVI can be placed inside it.

The technique, in his experience, is swift: it barely takes 20 to 30 minutes, and the team keeps talking to the patient throughout. Most transfemoral TAVI is performed under local anaesthesia, with or without light sedation.

TAVI access routes when the groin is unsuitable

The transfemoral route, through the femoral artery in the groin, is the commonest and safest way to reach the aortic valve. When the femoral arteries are too small, too calcified or too diseased, there are alternatives. Dr. Chandra described four.

Subclavian access

The subclavian artery runs beneath the collarbone. In one of his cases the femoral arteries were very small, under 5 mm, so the subclavian arteries were analysed on CT instead. A surgeon performed a cut-down to expose the artery, the valve was inserted through it, the native valve was crossed and pre-dilated with a balloon, and the new valve was deployed. The final angiogram showed no paravalvular leak.

Carotid access

When neither the femoral nor the subclavian route is suitable, TAVI can be done through the carotid artery in the neck. In the case he presented, the CT showed poor femoral arteries with heavy calcium, so the left carotid artery was chosen. Once the valve has been reached, the technique is as simple as from the groin.

Direct aortic access

The aorta can also be reached directly through a small opening in the chest, without the full sternotomy (division of the breastbone) of open surgery.

Transcaval TAVI

Transcaval TAVI uses the femoral vein to deliver a valve into the arterial system. The route is planned on CT and performed under CT guidance and fluoroscopy:

1. From the femoral vein, a wire is passed into the inferior vena cava, the large vein that runs alongside the abdominal aorta.
2. Just above the point where the aorta divides into the iliac arteries, a small hole is made from the inferior vena cava into the abdominal aorta.
3. The wire is caught inside the aorta with a snare and pulled up.
4. The delivery equipment, and then the TAVI valve itself, is advanced from the femoral vein through the inferior vena cava into the abdominal aorta, up the descending aorta and on to the heart.

Dr. Chandra described it as another novel way of doing TAVI for patients whose arteries rule out the conventional routes. At the end of the procedure, the opening between the vein and the aorta is sealed, typically with a closure device.

TAVI complications and how they are prevented

The main complications of TAVI are:

• Stroke, from debris dislodged from the calcified valve or aorta
• Conduction disturbances requiring a permanent pacemaker, which Dr. Chandra described as now minimal; the need for a pacemaker still varies with valve type and anatomy, and is generally higher with self-expanding valves
• Paravalvular leak around the new valve
• Coronary obstruction, when the displaced native leaflet blocks a coronary opening
• Groin and vascular complications at the access site

All of these, in his view, can be avoided by meticulous planning. Cerebral embolic protection devices, which capture debris during the procedure, are available to reduce the risk of stroke. Large randomised trials (PROTECTED TAVR, 2022; BHF PROTECT-TAVI, 2025) did not show a significant reduction in stroke with their routine use. For patients whose coronary openings are at risk, techniques such as BASILICA deliberately split the leaflet that would otherwise block the artery, preserving coronary flow.

He gave the groin particular weight. Mortality after TAVI can be very high if the operator is not careful with the access site: a patient can have a successful valve implant and still be lost because of a mismanaged groin. The operator must know how to manage it. His summary of complication prevention was a single word repeated: planning.

Valve-in-valve TAVI for a failed surgical valve

Valve-in-valve TAVI places a transcatheter valve inside a worn-out surgical tissue valve, sparing the patient a second open heart operation. Surgical tissue valves wear out with time, and reopening the chest for a second operation carries higher risk. Instead, a TAVI valve can be placed inside the old surgical valve, using its frame as the landing zone. Dr. Chandra's team offers this valve-in-valve procedure as part of its work with the most complex patients, including those with previous aortic valve replacement.

TMVR: transcatheter mitral valve replacement

The same valve, used in reverse orientation, can treat the mitral valve where a previous surgical mitral valve replacement has failed. This is transcatheter mitral valve replacement (TMVR), in this setting a mitral valve-in-valve procedure.

Planning again starts on CT. A virtual valve is placed in the mitral position on the scan to predict the neo-LVOT, the new outflow channel that will remain once the valve is implanted, because a valve that narrows it can obstruct blood leaving the heart. The procedure then follows the venous route:

1. From the right femoral vein, a transseptal puncture is made through the wall between the right and left atria.
2. A wire and sheath pass into the left atrium and on through the old mitral valve into the left ventricle.
3. The hole in the atrial septum is enlarged with a balloon so that it is big enough to take the new valve.
4. Under rapid pacing, the valve is positioned inside the old mitral prosthesis and inflated, just as in TAVI, and it seats in the mitral position.

The result is a mitral valve replaced without reopening the chest. When TAVI is the right choice over surgery in the first place, and what it costs, is covered in TAVI vs SAVR: how doctors decide. Doctors' questions to Dr. Chandra on preventing TAVI complications are answered in the Live Discussion from this masterclass, and related heart conditions are covered in the cardiology specialty hub.