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New Procedures

SIXTEEN

New Procedures

Aortic Stenosis is common in the elderly

and without treatment can carry a poor

prognosis with a 2-year mortality as high as

50-60% with continued medical therapy. In

addition, it also interferes with quality of life,

resulting in a reduced exercise tolerance.

This is due to shortness of breath and chest

pain, along with pre-syncopal or syncopal

episodes.

The standard treatment for this condition

is surgical Aortic Valve Replacement (AVR).

Although this can be a very successful

operation in patients with no co-morbidity,

in elderly patients with co-morbidities, it

can carry a very high risk, often resulting in

withholding of this therapy.

TAVI (Transcatheter Aortic Valve

Implantation) is a very exciting innovation

where the aortic valve is replaced without

the requirement for open heart surgery

or heart bypass. This new technique is

catheter-based, where a balloon expandable

valve mounted on a stent is delivered either

retro-gradely via the femoral artery or

ante-gradely, through a small incision at

the apex, below the left breast.

The stent is compressed on a deflated balloon to allow it to be introduced through a 6-7mm

sheath; it is then placed across the aortic valve and inflated in position.

SUITABLE PATIENTS

The procedure is currently restricted to

patients considered high surgical risk, or

those who have been turned down for

conventional AVR. The selection of suitable

patients is vital and involves a consultation

with both a cardiologist and cardiac

surgeon. The screening process usually

involves a 1-2 day hospital stay and includes

echocardiography, lung function, ultrasound

of carotids, CT of aorta and peripheral

vessels and coronary and peripheral

angiography. Following this, an assessment

can be made as to whether the TAVI

procedure is suitable and, if so, the intended

approach.

The decision to perform the procedure

via the femoral artery or apex is largely

down to the presence of peripheral

vascular disease – if the ilio-femoral vessels

are <7mm and/or significantly calcified or

tortuous, the procedure may need to be

performed apically.

THE PROCEDURE

The procedure is performed under general

anaesthesia by a team including cardiologists,

cardiac surgeons, echocardiographers and

anaesthetists. It is performed either ante-

gradely, via a 4-5cm incision at the apex to

gain direct access to the left ventricle or

retro-gradely via the femoral artery. In both

approaches, a valvuloplasty is performed

prior to introducing the valve mounted

on a balloon. After careful positioning

with angiography and trans-oesophageal

echo guidance, the balloon is inflated thus

deploying the valve in the position of the

patient’s own aortic valve.

RESULTS

Worldwide, implants total greater than

20,000. The success rate of the procedure is

approximately 97%. The predicted surgical

mortality in these patients is >20% and the

current trial data demonstrate that a 30-day

survival of 95-96% can be achieved. Clinically,

a marked improvement in symptoms and

quality of life has been demonstrated and this

appears to be maintained long-term.

Recently, a randomised trial (PARTNER

A and B) of over 1,000 patients has been

performed. The results were recently

presented and published and show that, in

patients deemed too high risk for surgery,

TAVI is associated with a dramatic reduction

in 1-year mortality compared to medical

therapy (30% versus 50% respectively). In

addition, in a separate arm of the trial, in

patients felt to be high risk but suitable for

open surgery, the two were found to be

comparable in terms of mortality.

Although this is still a relatively new

procedure, these results are highly

encouraging and it is likely that over time,

this therapy will become more widely

available to younger and less high-risk

patients.

New Procedures

– Aortic Stenosis

The structure of the valve, which is sewn into a

metallic stent.