FRCA Notes

Transcatheter Aortic Valve Implantation

TAVI in-and-of itself hasn't been a CRQ question, although marks were lost on a 2022 CRQ on aortic stenosis due to a lack of knowledge of the procedure.

Resources

  • The established treatment for severe aortic stenosis is surgical aortic valve replacement (SAVR)
  • TAVI may be preferable in an increasing number of patients, not just high-risk patients not suitable for SAVR but increasingly for those with lower risk surgical profiles too
  • It overall benefits from avoiding sternotomy and cardiopulmonary bypass, thus improving recovery times from the procedure
  • The main factors guiding choice of TAVI vs. SAVR are symptoms and prognosis, trying to encapsulate a more global assessment than simply relying on risk scoring systems

  • For TAVI, such patients include:
    • Severe, symptomatic aortic stenosis in whom SAVR is not suitable and there will be an appreciable QoL benefit from the procedure
    • Where various patient characteristics favour TAVI over SAVR:
      • Advanced age (>75yrs)
      • Significant comorbidity
      • Prior cardiac surgery, intact CABG or chest wall deformity
      • Porcelain aorta
      • Favourable vascular access
    • Putatively to facilitate other urgent non-cardiac surgery from which there is a survival benefit e.g. curative cancer surgery

Evidence base for TAVI (in brief)

  • All-cause 1yr mortality in high-risk surgical candidates similar to SAVR (PARTNER A Trial)
  • Reduced all-cause mortality & rehospitalisation vs. medical management alone, but higher risk of stroke (PARTNER B Trial)
  • Non-inferior all-cause 2yr mortality for intermediate-risk surgical candidates (PARTNER 2 & SURTAVI Trials)
  • Little-to-no difference for all-cause mortality, stroke, MI or cardiac death in low-risk surgical candidates (PARTNER 3, Cochrane)

Non-aortic stenosis indications for TAVI

  • Bicuspid aortic valve stenosis
  • Degenerated surgical bioprosthetic valve (i.e. instead of re-do cardiac surgery)
  • Aortic regurgitation (off-label use of procedure)

  • Active endocarditis (absolute)
  • Significant medical comorbidity with life expectancy <2yrs, e.g.:
    • Significant frailty
    • End-stage renal or respiratory disease
    • Severe mitral regurgitation
    • Severe pulmonary hypertension
  • Inadequate annulus size (either <1.8cm or >3cm)
  • Difficult anatomy
  • Mixed aortic valve disease or using TAVI for AR
  • Mobile thrombi in ascending aorta
  • Recent MI (1 month) or CVA (6 months)

Planning

  • Performed in a specialist centre with cardiac and vascular surgical support available
  • Large 'heart' MDT consisting of:
    • Cardiologists; TAVI operator, imaging specialists
    • Cardiothoracic surgeons
    • Vascular surgeons
    • Radiologists; vascular, cardiothoracic
    • (Cardiac) anaesthetists
    • ± Medicine for the elderly

  • Decision-making should not be guided by cardiac surgical risk scoring systems alone, but incorporate information regarding:
    • Clinical profile
    • Co-existing comorbidities
    • Functional status and frailty
    • Anatomical/technical factors inc. anticipated complexity
    • Pre-operative imaging e.g. gated cardiac CT

  • Adequate availability of cardiothoracic surgeons and perfusionists in case open approach and CPB is required mid-procedure

Vascular access

  • Primary access for 14-20Fr sheath
    • Trans-femoral access (90%); least invasive
    • Trans-subclavian (often left); shorter valve delivery distance means more accurate positioning and may reduce some complications (paravalvular leak, complete heart block)
    • Trans-apical; most invasive with a number of complications, but useful if trans-aortic approaches are unavailable
    • Trans-aortic; requires mini-sternotomy but may be necessary if other routes unavailable
    • Trans-carotid is described

  • Secondary access for 6Fr sheath; often right radial is used

  • Heparin IV bolus for a target ACT of 250s

Valve deployment

  • Options include:
    • Direct implantation of new valve, especially if there has been antecedent balloon valvuloplasty
    • Dilation of AV by balloon valvuloplasty then deployment of the new valve

  • If balloon valvuloplasty is performed, it requires temporary, rapid ventricular pacing in order to prevent migration of the valve
    • A temporary pacing wire is used, either arterial via existing femoral access or venous pacing wire via femoral vein or RIJV
    • Rate 180-220bpm
    • Associated intentional reduction in systolic arterial pressure to ≤50mmHg for 5-10s

Post-insertion

  • Device position and function is assessed using TTE or TOE
  • Vasculature is assessed with angiography
  • Vessels and entry points are repaired in standard fashion
  • ECG checked for dysrhythmia
    • Patients with a normal PR and QRS interval after TAVI tend not to develop delayed high-degree conduction disorders so the TPW is often removed
    • Otherwise patients may need ongoing temporary or even permanent pacing

Perioperative management of the patient undergoing TAVI


  • Planning as above (see: Surgical Process section)
  • Pre-operative assessment of the patient with aortic stenosis

  • Usually performed in the cardiac catheter lab so suffers from risks of remote anaesthesia

Monitoring and access

  • AAGBI
  • Continuous invasive arterial monitoring is provided by the interventional access sites
  • Large bore IV access in case of haemorrhagic complications
  • Consider CVC for administration of vasoactive drugs

  • TTE or TOE if under GA
  • Percutaneous defibrillation pads

Anaesthetic technique

  • Generally similar outcomes reported between GA and LA + sedation, although inadequately robust evidence base to confirm this (BJA, 2016)

  • Usually performed under LA ± conscious sedation for trans-femoral approaches

    • Benefits of LA + sedation for TAVI
    ↓ need for vasoactive drugs
    Negates need for invasive ventilation
    Facilitates intra-procedure neurological monitoring
    Shorter procedural time
    ↓ need for ICU
    Shorter length of stay
    More economical

  • GA may still be required; as per perioperative management of aortic stenosis
    • Benefits from immobile patient and ability to perform intra-procedure TOE
  • Regional techniques are described to provide analgesia for a trans-apical approach
  • E.g. thoracic epidural, paravertebral or intercostal nerve block; need to be mindful of need for anticoagulation

  • Cardiology ward or CCU in most uncomplicated cases
  • If I&V, extubate on CICU following standard post-cardiac surgery protocols

  • Maintain a high-normal intravascular volume status as:
    • There is poor LV compliance and diastolic dysfunction, so generally need higher filling pressures
    • There may be dynamic LVOT obstruction owing to a small LV cavity but normal contractility
  • VTE prophylaxis as indicated
  • Often go onto DAPT for 1yr, then single agent therapy lifelong

  • Often minimal analgesic requirements for trans-femoral approach
  • Other approaches may have greater analgesic requirements e.g.:
    • Trans-apical: consider paravertebral or serratus anterior plane blocks + PCA
    • Trans-carotid: consider superficial cervical plexus block ± PCA

  • Generally discharged 48-72hrs post-operatively

  • Females may be at higher risk of a number of in-hospital complications and all-cause mortality

Vascular

  • Overall rate of vascular complications 3-4%

  • Puncture site haemorrhage inc. retroperitoneal haemorrhage
  • Femoral artery pseudoaneurysm
  • Dissection
  • Vascular rupture
  • Bowel ischaemia due to atheromatous emboli

Conduction abnormalities

  • May be due to direct damage the AVN or bundle of His

  • LBBB (most common)
  • LV asystole or PEA during the procedure
  • Complete heart block
  • ~5% need PPM post-procedure

Peri-valvular

  • Paravalvular leak ± aortic regurgitation
  • Annulus rupture (<1%); naturally associated with a poor prognosis
  • Para-aortic haematoma
  • Aortic root rupture
  • Late valve failure (rare)

Coronary artery occlusion

  • Typically due to displacement of the native calcified valve leaflet over the coronary ostium
  • May warrant catheterisation of the coronary arteries prior to implanting the valve to ensure easy access to re-open occluded arteries
  • Patients who are undergoing valve-in-valve (i.e. redo) TAVI are at higher risk
  • Overall incidence <1% but associated with poor outcome

Other

  • Stroke (2-5%)
  • Delirium; higher risk if GA technique used (53% vs. 12% for sedation)
  • Acute rise in creatitine (5-28%)