TAVI

Question 1

By reading this article, you should be able to

Answer 1

*
Describe the grading of aortic stenosis and the role of multimodality imaging to guide management.
*

Explain the limitations of traditional surgical risk classification of low, intermediate or high risk; and the refinement in assessment needed to identify which patients with severe aortic stenosis are best candidates for transcatheter aortic valve implantation (TAVI).
*

Discuss the evidence for TAVI in patients deemed high risk for aortic valve surgery (with or without coronary artery bypass grafting).
*

Outline the increasing evidence for surgery and TAVI as complementary modes of intervention in lower-risk groups.

Question 2

Key Pts

Answer 2

1 Patients with symptomatic severe aortic stenosis have a high risk of death.

2 Management options include surgical aortic valve replacement, medical therapy and transcatheter aortic valve implantation (TAVI).

3 Although echocardiography is the main tool used to grade aortic stenosis,
CT is emerging as the modality to assess the need for interventions to the aortic valve and the broader evaluation of structural heart disease.

4 Transcatheter aortic valve implantation is non-inferior to surgical aortic valve replacement in intermediate- and lower-risk candidates for surgery. It is likely that many more patients will be offered TAVI in the future.

5 It is essential that the anaesthetist providing perioperative care knows the current guidelines and evidence for TAVI.

Question 3

Aetiology

Pathophysiology of aortic stenosis

Answer 3

Normal aortic valve area (AVA) is 2.6–3.5 cm2 in adults

Clinically relevant aortic stenosis occurs as the AVA approaches 1.0 cm2,
and the aetiology is usually degenerative or congenital

increasingly a degenerative condition associated with ageing.

Degenerative calcific aortic stenosis is more common in the UK and
tends to affect people aged >70 yrs.

Mechanical stress leads to degeneration of the previously normal tricuspid valve leaflets, giving the appearance of sclerosis when imaged with echocardiography. This form of aortic stenosis is associated with risk factors for coronary artery disease.

_____________________________________________________

1. As left ventricular outflow obstruction increases,
   the left ventricle becomes increasingly hypertrophied.
2. This process eventually becomes harmful,
   with a decrease in stroke volume,
   compliance and elasticity,
   and diastolic dysfunction
   - *preserved ejection fraction

3 Increased left atrial pressure with increasing diastolic dysfunction and subsequently increased pulmonary arterial pressure can lead to exertional breathlessness; symptoms may occur without aortic stenosis being severe

4. The left ventricle becomes increasingly dependent on atrial contraction for filling, and atrial fibrillation is tolerated poorly.
   Symptoms are associated with adverse outcomes and commonly develop when compensatory mechanisms begin to fail.

5 untreated symptomatic severe aortic stenosis has a 1-yr mortality approaching 50%

6 Chest pain and breathlessness arise from a mismatch in myocardial oxygen supply and demand, even in patients with normal coronary arteries.

7 Cardiac output becomes sensitive to changes in preload and arterial systolic pressure

8 Syncope (usually after exertion) can occur secondary to
reduced cardiac output and hypotension

9 Eventually, the left ventricle becomes dilated and the syndrome of heart failure ensues

10 For patients with aortic stenosis, management options for their condition include surgical aortic valve replacement, TAVI, balloon aortic valvuloplast

Question 4

Recommendations for grading of aortic stenosis severity

Severe
(mild)

Answer 4

2017 European Society of Cardiology,

Peak velocity
≥4.0m/s
(2.6)

Mean gradient (mmHg)
>40
(20)

AVA
Cm2
<1
(>1.5)

velocity ratio
<.25

Question 5

Classification of patients with and management of severe aortic stenosis

Answer 5

Transthoracic echocardiography is the key mode for assessing the presence and severity of aortic stenosis (Table 1). The 2017 European Society of Cardiology, European Association for Cardio-Thoracic Surgery and the European Association of Cardiovascular Imaging recommended a stepwise approach to grading of severity

Question 6

There are four diagnostic categories of severe aortic stenosis.

Answer 6

First is high-gradient aortic stenosis,
which can be assumed irrespective
of ejection fraction and flow.

Second is low-flow low-gradient
aortic stenosis with a reduced ejection fraction.

Third is low-flow low-gradient aortic stenosis with a preserved ejection fraction, typically seen in the elderly

Fourth is normal-flow low-gradient aortic stenosis with a preserved ejection fraction, which encompasses those patients who will usually only have mild disease.

Question 7

Other Ix for AS

Answer 7

1. Exercise testing can be useful to risk stratify patients who are physically active.
2. Transoesophageal echocardiography may be useful
   to look in more detail at other structures,
   such as the mitral valve,
   but it is no longer routinely used before TAVI.
3. CT scanning is the standard modality for aortic valve procedures,
   TAVI assessment and structural heart disease assessment more broadly,
   and is a rapidly evolving area in preoperative assessment

Most centres in the UK do not routinely quantify aortic valve calcification; yet, it may be considered when Doppler echocardiography data are discordant.
score by CT scan can play an increasingly important role in these groups using the Agatston method

4. stress echocardiography or CT assessment of valvular calcification as a flow-independent marker of more severe disease

5 Cardiac magnetic resonance imaging has a more limited role. However, its importance for quantifying myocardial fibrosis and identifying dual pathology is recognised,

6. Serum brain natriuretic peptide concentrations can be
   useful for surveillance in asymptomatic patients
7. LHC - rare in clinical practice

Question 8

Indications for TAVI

Answer 8

severe aortic stenosis in which surgical aortic valve replacement is not suitable

Severe comorbidity

Age ≥75 yrs

Previous cardiac surgery

Favourable vascular access

Porcelain aorta

Intact coronary artery bypass grafts

Chest wall deformity

Question 9

Surgical aortic valve replacement

Answer 9

• Logistic EuroSCORE <10%
• Valvular endocarditis
• Short distance between coronary ostia and aortic valve annulus
• Size of aortic valve out of TAVI range
• Unfavourable valve morphology
• Left ventricular thrombus
• Severe coronary artery, mitral, tricuspid or aortic disease requiring surgical intervention
  __________________________________

Broadly, asymptomatic patients with a reduced ejection fraction are offered surgery

Asymptomatic patients with a normal ejection fraction, who are not physically active, have risk factors severe valve calcification, high peak velocity or progression and pulmonary arterial hypertension low risk for surgery are offered surgery.

Question 10

Contraindications to TAVI

Answer 10

The only absolute contraindication to TAVI is active endocarditis

Patient-related factors include
comorbidity or frailty precluding improvement of quality of life
and estimated life expectancy <2 yrs.

Technical factors include inadequate annulus size (<18 and >30 mm);

including short distance between the annulus and coronary ostium;
.
valve morphology; off-label use in severe aortic regurgitation

Question 11

Approaches

Answer 11

usually performed - femoral arteries

subclavian arteries

cardiac apex

directly into the aorta

Question 11

Evidence

Answer 11

30d mortality
low<4%

High Risk >8%

Partner A B
A - non inferioity - similiar 1 yr mortality

B - vs medical tx - tavi reduced mortality
CVA more common

Partner 2 - TAVI in intermed risk - non inferior all cause mortality at 2 years

PARTNER 3
educed incidence of postoperative atrial fibrillation, acute kidney injury and bleeding

Question 12

Role of the preoperative multidisciplinary ‘heart team’

Answer 12

1. TAVI registry
   Adverse events reports
2. Patient selection MDT

TAVI Operator

Cardiac Surgeon

Imaging cardiologist

Multidisciplinary team input from other specialties, including anaesthesia, vascular radiology, vascular surgery and medicine for the elderly, will be required for some patients;

3. during the consent process, patients should be told about all treatment options, including their advantages and disadvantages.
4. Specialised centres
   clinicians with xperience and training

There should be cardiac and vascular surgical support available, should complications develop, which may need to be addressed urgently.

Question 12

Organisational

Answer 12

Multidisciplinary TAVI ‘heart team’.
This team should include interventional cardiologists,
cardiothoracic surgeons,
valve clinic coordinators,
cardiac catheter laboratory staff,
a cardiac anaesthetist,
the referring cardiologist,
a structural heart disease expert and a
cardiac radiologist
and a geriatrician.

Question 13

Risks benefits

Answer 13

Need careful weighing along with patient factors and the preference of patients and other key stakeholders

coexisting medical conditions, are elderly and may be frail, which all make the risk/benefit assessment challenging.

Technical suitability and peripheral arterial access

Question 14

By reading this article, you should be able to:
*

Answer 14

1. Explain how technological advances and increased experience with transcatheter aortic valve implantation (TAVI) have reduced the requirement for general anaesthesia, transoesophageal echocardiography and pulmonary artery catheter insertion.
2. Detail the basic steps involved, including vascular access, valve deployment, haemostasis of primary interventional access and the implications of each step for the anaesthetist.
3. Describe the minimalist approach to TAVI, the possible complications and their management.

Question 15

Key points

Answer 15

1 The anaesthetist has several important roles in TAVI,
including perioperative preparation,
leadership,
risk mitigation
and management of complications.

2 The most common approach is transfemoral TAVI,
with vascular access of the femoral artery
using 14–20 Fr gauge systems.

3 Some steps require rapid ventricular pacing at
180–220 beats/min
to reduce the systolic blood pressure to
<50 mmHg for 5–10 s.

4 Injury to the femoral artery is common and
open surgical repair under general anaesthesia may be needed.

5 Other important complications include conduction abnormalities,
such as heart block requiring a permanent pacing system,
coronary artery occlusion
and stroke.

Question 16

Advantages of TAVI

Answer 16

1 avoidance of sternotomy

2 cardiopulmonary bypass,

3 expedited recovery from the procedure.

Question 17

Planning

Answer 17

Selection of patients

Net superiority of TAVI over surgical aortic valve replacement (SAVR) in high- and intermediate-risk patients.
surgical risk scores (EuroSCORE or Society of Thoracic Surgeons score)

Gated cardiac CT has become a standard of care for patients undergoing TAVI for aortic valve, aortic root and vascular access assessment.
anatomical and technical factors to be considered

It also allows for tailoring of transcatheter heart valves to the patient’s anatomy, which may result in better outcomes;

assess
iliofemoral anatomy
suitability for access
alternatives

Question 18

Transcatheter heart valves

Answer 18

TAVI are balloon- and self-expandable devices.

Question 19

Transcatheter aortic valve implantation: step by step

Answer 19

TAVI procedure are
vascular access,
valve deployment and
haemostasis of primary interventional access

Before deployment, access to the femoral artery is achieved with ultrasound guidance.

A transvenous pacing wire can also be inserted in the femoral vein.

Vascular complications at this stage include
bleeding,
dissection and
rupture.

Balloon valvuloplasty is not always required,
but allows for easier passage of the prosthesis.

This may necessitate 5–10 s rapid ventricular pacing at 180–220 beats min.

Small doses of vasopressor may be required after these short periods.

Deployment may cause interruption of cerebral perfusion,
and this phase must be undertaken rapidly.

Problems at this stage include:

migration into the aorta or left ventricle,
paravalvular regurgitation,
incorrect placement,
obstruction of the coronary ostia,
arrhythmia,
cardiac arrest,
heart block, and
impingement of the mitral valve leaflet.

After deployment,
the delivery system is removed,
the position and function of the valve are checked,
and the coronary vessels are imaged.

The femoral vessels may need to be repaired if
the on-table angiography demonstrates any evidence of bleeding.

Question 20

Steps relevant to anasethesia

Answer 20

1. Vascular access

Heparin is given i.v. at a bolus dose of ∼3000–5000 units
and repeated to achieve an activated clotting time of at least 250 s

2. Valve deployment
   Rapid pacing is required during balloon aortic valvuloplasty
   and is particularly important when deploying
   balloon-expandable valves to prevent migration of the valve.

Right ventricular pacing at a rate of 180–220 beats min−1 to reduce the systolic arterial pressure to below 50 mmHg and lasts for 5–10 s

Ultimately, if the result is unsatisfactory and refractory to further interventions, implantation of a second prosthesis might be necessary as a bailout procedure.

3. Haemostasis
   devices to close the artery based on sutures or a collagen plug are used for haemostasis.

Question 21

Minimalist TAVI

Answer 21

The following general principles of the TAVI procedure remain essential to safe outcomes:

1. Safety WHO checklist and role allocation;
2. Patient-specific briefing for preparedness,
   anticipation of and equipment for potential complications;
3. Clear communication by all team members;
4. No barriers to individuals speaking up or alerting the team to problems.

Question 22

Changes

Answer 22

Previously, most patients would receive general anaesthesia, which would be of a ‘cardiac’ type including high-dose opioids, neuromuscular blockade, tracheal intubation, transoesophageal echocardiography, invasive arterial monitoring and central venous access

Now, infiltration of local anaesthesia with or without conscious sedation is preferred for transfemoral approaches.

if General anaesthesia is required, the general principles of anaesthetising patients with aortic stenosis apply, such as tracheal intubation with neuromuscular blockade; maintaining a low/normal heart rate (∼55 beats.min−1), sinus rhythm and adequate intravascular volume; and high/normal systemic vascular resistance. Inotropic drugs, heavy premedication or rapid i.v. infusion of fluids are not commonly required during induction of anaesthesia for TAVI.

Question 23

Local anaesthesia and conscious sedation

potential benefits

Answer 23

1. shorter procedural time
2. direct communication with the patient
3. Reduced vasopressors
4. Reduced Critical care requirement
5. Shorter LOS
6. Lower resource use
7. paucity of randomised evidence comparing various techniques
8. RCT - outcomes ere similar between those undergoing general anaesthesia and local anaesthesia with conscious sedation.

Question 24

LA

Answer 24

with or without a cardiac anaesthetist present. Increasing experience has emphasised greater importance on a TAVI team member at the patient’s ‘head end’ who is dedicated to communicating with the patient,

allaying anxiety and where necessary, managing the airway.

1. LA without anaes
2. LA with standby cardiac anaesthetist
   patient specific factors
   inotropes
   msk disease
   back pain
   cornaroy occlusion risk
3. GA used with alternative access routes
   local unfavourable

Question 25

Monitoring and vascular access

Answer 25

Continuous ECG monitoring and pulse oximetry are required, as per minimum standards of perioperative monitoring

Sedation drugs are given, waveform capnography monitoring in conjunction with oxygen delivery through a Hudson mask is recommended.

Continuous invasive arterial monitoring is provided via the primary interventional and secondary access sites

One peripheral i.v. access cannula is required for routine TAVI cases via a percutaneous transfemoral approach under local anaesthesia

Femoral venous access may be provided (or taken via the sheath for the transvenous pacing wire if used) in higher-risk cases

Question 26

Pacing

Answer 26

Routine use of a balloon-tipped temporary pacing wire
potentially reduces the risk of right ventricular perforation
with a fixed transvenous pacing wire

A temporary transvenous pacing wire may be avoided by pacing the left ventricle via the stiff guidewire in the left ventricle.

a transvenous pacing wire is used (mainly for balloon expandable valve deployment), it is removed in the catheter laboratory in most cases after assessment of the ECG after TAVI and with the help of a prespecified protocol based on studies predicting development of high-degree conduction disturbance

normal PR and QRS interval after TAVI did not develop delayed high-degree conduction disorders, and these patients are naturally the best candidates for remova

Question 27

Complications

Answer 27

1. Vascular access
   Computed tomography analysis,
   routine ultrasound-guided femoral arterial puncture and improved,
   lower profile valve delivery systems and sheaths have significantly reduced vascular complications to ∼3%
2. Conduction abnormalities
   direct damage on prosthesis deployment
   LBBB
   complete AV block ppm
3. Coronary artery occlusion
   The incidence of coronary artery obstruction is generally <1%, yet is associated with a very poor outcome
4. Aortic annulus rupture
   The incidence of aortic root or annulus rupture is <1%
5. Stroke
   2%

Question 28

Emergency conversion to GA

Answer 28

If it is necessary to convert to general anaesthesia, the general principles of anaesthetising a patient with aortic stenosis apply.26 These include: ensuring application of defibrillator pads, which should already be in place from the start of the procedure;
; maintaining myocardial oxygen delivery via adequate systemic pressure and diastolic time; maintenance of contractility; optimising preload for a non-compliant left ventricle; and defending sinus rhythm at a rate of ∼55 beats

An opioid-based technique minimises vasodilation and negative inotropy, and can be supported with i.v. doses of an alpha adrenergic agonis

Question 29

Postoperative care and discharge

Answer 29

Now, most patients can be safely cared for on a coronary care unit or monitored cardiology ward.

Postoperative critical care is only required for specific indications or if unexpected major complications occur.

require a temporary or permanent pacemaker system after the procedure

Analgesia requirements are minimal, and oral paracetamol is usually sufficient.

risk assessed venous thromboembolism. Inpatient prophylactic low-molecular-weight heparin is required, but patients do not require long-term anticoagulation. Patients are discharged usually from hospital after a short period of recovery of approximately 2–3 days.