Pushing boundaries in minimally invasive aortic valve surgery: ART-AVR

Consultant cardiac surgeon Mr Govind Chetty was the driving force behind bringing the minimally invasive anterior right mini-thoracotomy aortic valve replacement (ART-AVR) to Sheffield Teaching Hospitals NHS Foundation Trust. Here, he talks to Allie Anderson about how he’s making best use of ART-AVR and why training in this technically demanding surgery is beneficial for both aspiring cardiac surgeons and patients alike.

Originating from the Seychelles and having studied medicine in India, Mr Govind Chetty came to the UK in 1995. He began training in cardiothoracic surgery, taking up his first consultant post in Cardiff in 2013. Two years later, Mr Chetty headed to the ‘Steel City’ where he set up the minimal access aortic valve and aortic aneurysm surgery programme at Sheffield Teaching Hospitals NHS Foundation Trust.

Today, Sheffield is one of the only centres in the UK to offer the minimally invasive anterior right mini-thoracotomy aortic valve replacement (ART-AVR). Under Mr Chetty’s tutelage, cardiac surgeons from the UK and further afield have learned this ground-breaking surgical technique for treating aortic valve disease – stenosis or regurgitation.

Minimally invasive aortic valve replacement

Aortic valve stenosis is a progressive condition more often marked by degenerative calcification and stiffening of the aortic valve, thereby not allowing blood to freely flow out of the heart. This puts the heart under pressure overload, which can lead to heart failure.

An estimated 300,000 people in the UK aged 55 and older are affected by the condition, yet many are unaware until it has reached an advanced stage.

Researchers predict that more than half of the people with untreated, advanced disease will die within five years. As such it represents a significant burden for healthcare systems.

Surgical aortic valve replacement was first performed in 1960 and remains the gold-standard treatment. Conventional, open surgery involving full sternotomy has been surpassed by developments in minimally invasive techniques in the 1990s and early 21st century.

According to Mr Chetty, technological advancements in artificial valves was a starting point for adopting minimally invasive techniques.

‘When I came to Sheffield in around 2015, we started using rapid deployment and sutureless valves. With the introduction of these valves, the interest in using minimally invasive surgery came about,’ he recalls. ‘Since we didn’t have that in our department, I was very keen to introduce it.’

Mr Chetty chose to focus on ART-AVR, which was first described in the literature in 1997. Instead of cutting through the sternum – a requirement of traditional open surgery – a transverse intercostal incision of around 5cm to 6cm is made, often between the second and third ribs. The valve is accessed through that small incision, with care taken to avoid injuring the ribs.

This technique has manifold advantages for patients, as Mr Chetty explains. ‘It causes less pain because you are not cutting any bone, and patients are able to use their arm and upper body immediately after surgery with no restriction whatsoever. Therefore, they can mobilise better,’ he says.

‘It’s a quicker recovery for patients, because with a full sternotomy, they are restricted in using their arms to get out of bed because it can cause destabilisation of their sternum, whereas with ART-AVR you don’t have to worry about that.’

In addition, the smaller incision means a more cosmetically pleasing scar, reduced bleeding and therefore decreased need for blood or blood product transfusion, less time in ICU and fewer days in hospital, and a shorter recovery time.

‘We normally advise patients not to drive for six weeks after the conventional surgery, whereas with ART-AVR they are able to drive a couple of weeks later,’ says Mr Chetty. ‘Most patients can go back to work much earlier, usually after a couple of weeks.’

Drawbacks of ART-AVR

Patients undergoing aortic valve replacement require cardiopulmonary bypass (CPB) support, and as such, the term ‘minimally invasive’ may be misleading. It has been suggested that ‘minimal access’ is a more accurate description.

Typically, surgeons place a cannula in the femoral artery in the groin to put the patient on bypass. That can lead to certain complications such as trauma to the vessels, possibility of infection and additional pain for patient. Retrograde perfusion may also be linked with a higher risk of neurological and vascular complications.

Mr Chetty’s technique instead entails CPB by direct cannulation of the aorta, as done in the conventional open technique.

‘The advantage of femoral cannulation is that it gives you more space to work in the small hole in the chest, so it makes the surgeon’s life a little bit easier,’ he explains. ‘But from the beginning I trained myself to use the same incision and I’m comfortable with that.’

This technique also minimises the risk of potential complications associated with femoral cannulation.

Furthermore, central aortic cannulation enables him to use standard cannulas that are used in open surgery, rather than femoral cannulas that come at a significantly higher cost.

‘These cannulas can be expensive – up to £400 each – so we’re looking at £800 extra for them,’ Mr Chetty says. ‘Use of rapid deployment or sutureless valves can help facilitate the procedure, but these are more expensive. In my practice, I tend to use conventional valves, so there is no increased cost.’

Patient selection

Not all patients are suitable for this minimal access procedure. Much depends on the position of the patient’s aorta, which must be accessible through the intercostal incision. Therefore, if the patient’s whole aorta is located behind the sternum, ART-AVR will not be possible, says Mr Chetty.

‘I organise a CT scan for my patients, and I judge whether I can perform the ART surgery based on that. If the aorta is 50% or more displaced to the right-hand side, meaning I can see at least half of it to the right of the sternum, then I am able to offer the procedure to my patients,’ he explains.

In patients whose aorta is not positioned suitably, a mini-sternotomy is an alternative to full sternotomy. This involves an incision from the top of the breastbone about one-third down, making it more invasive than the ART-AVR but less traumatic than splitting the breastbone in half as per a full sternotomy.

Some patients cannot safely undergo surgical valve replacement because of a higher risk of serious complications or death, such as patients who are frail, immobile and very elderly, or those with significant comorbidities. In such cases a transcatheter aortic valve implantation (TAVI) is preferable, which usually requires no general anaesthetic or CPB support.

However, TAVI is not without drawbacks, as Mr Chetty details. ‘There is an increased risk of requiring a pacemaker after the TAVI procedure, and then the length of stay will be almost the same as if they had conventional surgery,’ he says. ‘TAVI is usually done through the groin, so complications related to trauma to the vessels in the groin may also increase the length of hospital stay.’

Learning and sharing knowledge

To bring the ART-AVR procedure to Sheffield, Mr Chetty first had to learn the technique from peers. He took a team of clinicians to Centre Hospitalier Universitaire de Dijon Bourgogne, where they observed two ART-AVR procedures before beginning training themselves.

‘We brought a proctor to Sheffield and we set up some cases. I did those with the proctor overseeing, and then was signed off to be able to carry on,’ he says.

The student has since become the teacher, and Mr Chetty has delivered training to junior consultant colleagues, as well as leading a human cadaveric course for surgeons from across the UK. More recently, doctors from Malaysia have visited Sheffield to learn the technique.

‘In our unit we also host minimal access fellowships,’ he adds. ‘Candidates can apply through the Society of Cardiothoracic Surgery of Great Britain for placements. We have had two so far, who are now in consultant posts.’

The learning curve for performing the ART-AVR is slightly steep, and extensive experience in minimal access surgery with midline incision is required, according to Mr Chetty.

‘I think surgeons should have done at least 30-50 mini-sternotomies and be very comfortable with this before they can embark on the ART procedure. That gives you a perspective of how to operate in a small space, and you must be very comfortable to manage possible complications.’

The future of minimal access ART-AVR

Advancements in options and techniques mean that wider cohorts of patients are increasingly offered the non-invasive TAVI procedure. However, treatment decisions should be made in consultation with patients by multidisciplinary specialist clinicians, says Mr Chetty.

‘It should be a collaboration, not a competition,’ he comments. ‘All patients with aortic valve disease should be streamlined into a referral system where they are taken care of by an aortic valve management team.’

Minimal access AVR surgery is still growing as a discipline. UK National Institute for Health and Care Excellence guidelines recommend that if it is the preferred option but unavailable locally, patients should be referred to a centre where it is available. Where there is rising demand, there must be more skilled surgeons to meet it.

‘A giant of minimally invasive cardiac surgery, Professor Friedrich Mohr of Leipzig Heart Centre, once said, “It’s painless for the patient but more painful for the surgeon”, so one must have that mindset,’ Mr Chetty comments.

‘We need to encourage younger surgeons and trainees to take up minimally invasive cardiac procedures, even though it is more technically demanding. There is no doubt the demand for it will increase to meet patients’ expectations and choices.’