Feature


JAP  Volume 7 Issue 1


TAVI at the heart of it all


Not every patient to come in presenting with aortic stenosis (AS) is suitable for cardiac surgery. Transcatheter aortic valve implantation (TAVI) is a favourable alternative for them, but this is still not without its difficulties when it comes to anaesthetic management, sayDr Gokulnath Rajendran andDr Stephen Webb.


T


he prevalence of AS is higher in old age (Table 1).1 The commonest cause of aortic stenosis is degenerative calcific aortic valve disease (Table 2).1


Calcific aortic valve disease The risk factors are similar to those for developing atherosclerosis (male, old age, hypercholesterolemia, diabetes). Fibrosis and calcium deposition in the valve initially results in sclerosis and gradually stenosis develops during or after the sixth decade. This process seems to be accelerated if the native aortic valve is bicuspid, and in these cases stenosis occurs by fourth decade.


Congenital aortic stenosis Congenital unicuspid, unicommissural valve disease usually presents in early childhood or adolescence. These children either die (sudden death) or receive AVR at an early age.


Rheumatic valve disease This is a very rare cause of AS. Most often it is associated with rheumatic mitral valve disease and the aortic stenosis is due to commissural fusion rather than calcification.


Indication for intervention The normal aortic valve area is three to 4cm2


. The main symptoms


of AS include angina, syncope and breathlessness. Symptoms may not correlate with severity of stenosis, and when the valve area is <1cm2


medical management and balloon valvuloplasty is poor.3 , it is classified as ‘severe AS’. If left untreated, it is


associated with a survival of two to three years and the incidence of sudden death is 10-15 percent per year.2


The evidence supporting The ‘gold


standard’ treatment for symptomatic severe AS is surgical AVR. For those considered high risk for surgery, TAVI is currently the treatment of choice. The UK National Institute for Health & Clinical Excellence (NICE) states that evidence for the efficacy of TAVI is sufficient to recommend the procedure for those unsuitable for surgery, but that there is insufficient evidence to support it for those who are considered suitable for surgery.4


TAVI procedure The procedure involves balloon valvuloplasty of the stenosed valve


followed by deployment of a bioprosthetic stent within the aortic annulus. Reversible, temporary cessation of cardiac output by right ventricular pacing (for brief period of approximately 10 seconds) enables optimal deployment of the stent. Two types of stents are currently available in Europe: the self-expanding CoreValve ReValving System (CoreValve ReValving Technology Medtronic Inc., Minneapolis, MN, USA) and the balloon-expandable Edwards SAPIEN


Abstract Aortic stenosis (AS) is the most common valvular heart


disease in developed countries. As people live longer, the incidence of AS continues to rise. Transcatheter aortic valve implantation (TAVI) is a less invasive alternative to surgical aortic valve replacement (AVR) for patients considered high risk or not suitable for cardiac surgery. Anaesthetic management for TAVI can be challenging as these patients often have multiple severe co-morbidities. Perioperative care should involve multi-disciplinary planning. In this review, we discuss the perioperative management of patients with severe AS undergoing TAVI.


valve (Edwards Lifesciences, Irvine, CA, USA). The most common approach to the aortic valve is a retrograde approach via the femoral artery. Other less common approaches include: • transapical (an antegrade approach to the left ventricular apex via a left lateral minithoracotomy)


• transaortic (retrograde approach via the ascending aorta by a ministernotomy)


• transaxillary (retrograde approach via the axillary artery by a surgical cutdown)


In the UK, the procedure is undertaken in specialised cardiothoracic centres jointly by interventional cardiologists and cardiothoracic surgeons with support from echo cardiologists and cardiothoracic anaesthetists. TAVI is performed in ‘hybrid cardiac catheterisation room’ (which contains operating theatre facilities in a cardiac catheterisation room) with a cardiopulmonary bypass circuit and clinical perfusion scientist available on stand-by.


Preoperative investigations Preoperative investigations for TAVI are summarised in Table 5.


Multidisciplinary team meetings including all staff involved in the planned procedure, should take place preoperatively. The anaesthetist plays a major role in preoperative assessment of patients undergoing TAVI. The type of anaesthesia and the postoperative level of care are determined by patient characteristics and premorbid status. Full blood count, electrolytes and renal function should be checked. Packed red blood cells must be cross- matched. Although practice varies between centres, single or dual anti-


platelet (aspirin, clopidogrel) loading doses (300mg) are commonly administered preoperatively and 75mg daily continued postoperatively for three to six months. Preoperative intravenous (IV) crystalloids should be considered to prevent contrast-induced nephrotoxicity.


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