European Association for Cardio-Thoracic Surgery 29th Annual Meeting 2015 Blog – Michael Seco

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Aortic Valve Repair

Atrio-Ventricular Valves

Heart Failure Surgery

Minimally Invasive Mitral Valve Surgery

Sutureless Aortic Valve Replacement

 

 Aortic Valve Repair

Aortic root anatomy
  • Reviews: de Kerchove et al. JTCVS 2015 & de Kerchove et al. ACS 2013
  • Aortic root (aka functions aortic annulus) – lower limit is the ventricle-aortic junction (VAJ, aka surgical annulus) & upper limit is the sinotubular junction (STJ)
  • Normal VAJ area changes during cardiac cycle – increased during isovolumetric contraction & ejection, decreased during isovolumetric relaxation, increased during diastole
  • Normal aortic annulus is oval & becomes more circular with dilation
  • The annulus is larger in a bicuspid AV than a tricuspid AV
  • The annulus becomes progressively larger with increased degree of AR

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Aortic insufficiency repair classification
  • Boodhwani et al. JTCVS 2009
    • type 1 – due to dilation of the AAo ± STJ ± sinuses of Valsalva ± VAJ or cusp perforation
    • type 2 – due to leaflet prolapse (excessive cusp tissue or commissural disruption)
    • type 3 – due to leaflet restriction (BAV, calcification, fibrosis, rheumatic)

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Aortic annuloplasty
  • Re-establishing normal annulus diameter is the basis for successful AV repair
  • When you need to do an annuloplasty:
    • Bicuspid AV annulus – 29-30mm
    • Tricuspid AV annulus – 28mm
    • STJ : VAJ ratio should also be between 1 – 1.5
  • Surgical dissection down to the annulus in VSARR:
    • NC sinus – limit is fibrous portion of the VAJ (aorto-mitral continuity)
    • NC/RC commissure – limit is membranous septum
    • RC sinus – limit is muscular septum (myocardium of interventricular septum & RVOT)
    • RC/LC commissure – limit is muscular septum
    • LC sinus – limit is roof of LA – the only area where dissection reaches the nadir of the leaflet hinge line
  • Options for annuloplasty:
    • Subcommissural annuloplasty (Cabrol stich)
      • Also increases valve coaption by closing the inter-leaflet triangles (sometimes used for this purpose instead of annuloplasty)
      • Annuloplasty is not stable over time – recurrent dilation can occur in the portions between the plication sutures – Vallabhajosyula et al. ATS 2014 & Hanke et al. JTCVS 2009
      • Also creates asymmetrical shape, abolishes normal physiology in the inter-leaflet triangles
    • External ring annuloplasty
    • Internal ring annuloplasty
      • Dacron strip
      • Novel preformed ring – 2yr follow-up showed good result – Mazzitelli et al. EJCTS 2015
      • Ring is close to leaflet insertion ?impingement, ?does it induce fibrosis that could extend to the leaflet

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Effective & geometric heightscreen-shot-2015-10-09-at-12-28-12-pm
  • standardised measurements used for cusp resuspension during VSARR
  • effective height (eH) – distance between the aorta-ventricular (basal) plane & central caption level
    • Schäfers et al. JTCVS 2006
    • used as indicator of cusp prolapse
    • requires a normal amount of cusp tissue i.e no cusp retraction (e.g. ageing & inflammatory conditions)
  • geometric height (gH) – maximum tissue height of the cusp
    • Schäfers et al. JTCVS 2013
    • cusp retraction defined as ≤16mm in tricuspid AVs & ≤19mm in BAVs
      repair of retracted cusps do not do well & should be replaced instead

 

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AV leaflet repair techniques
  • types of patches
    • autologous – fresh, glutaraldehyde-treated
    • xenograft – pericardium, anti-calcification, decellularised, ECM
    • synthetic – Gore-Tex, synthetic ECM
  • techniques
    • partial cusp repair – perforation, fenestration, commissure, raphe, cusp extension, unicuspid/dysmorphic valve
    • full cusp repair
    • aortic valve reconstruction (Ozaki procedure)
  • patch use is known to be associated with decreased durability of repair/recurrent AI

 

Aortic valve reconstruction
  • Ozaki operation is method of aortic valve reconstructiong645_1
  • Study looked at performing the Ozaki operation using Cardiocel in sheep
    • Echo at 6 months showed valves functioning well
    • Explant showed preserved structure & stability of the Cardiocel tissue
    • Low rate of calcification
    • Neo-intima formation & re-cellularisation with host cells

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Haemodynamics of David procedure
  • 3D aortic root geometry & flow dynamics were assessed during the cardiac cycle in pigs with native aortic root or David procedure
  • The David root is exposed to high pressures & low shear stress for a longer time during the cardiac cycle than the native aortic root, which would favour degeneration
  • However clinical outcomes have of the David have been very good – perhaps there is leaflet remodelling that occurs in response to this pressure
  • Not presented specifically, but apparently when same model was applied to the Yacoub repair the haemodynamic profile was superior to the David & closer the native aortic root

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Atrio-Ventricular Valves

Parachute ventricular partitioning
  • Used to partition off & exclude an apical aneurysm & increase EF
  • Nitinol-based PTFE covered parachute-like device
  • Transfemoral delivery
  • Guide catheter points at the landing zone in the ventricular apex, the device is deployed, & a balloon is used to expand the nitinol frame

Transcatheter Mitral Valve Implantation (TMVI)
  • Number of differences in the MV compared to the AV that makes designing transcatheter devices challenging
  • Differences in anatomy
    • Larger size & D shape
    • Complex subvavular apparatus
    • Some cords insert into the leaflet body rather than the free margin, the anterior commissure is close to the AV,
    • The MV is also close to the circumflex artery
  • Differences in physiology
    • MV separates low-resistance from high-resistance, whilst AV separates high-resistance from high-resistance
    • MV has low-resistance inflow (diastole) & high-resistance outflow (systole)
    • Annulus changes dimensions up to 40% in systole
    • Both aetiology & affected structures are highly varied
  • Differences in design priorities
    • Aim to decrease or maintain the EOA, as opposed to maximising
    • The height of the device affects risk of LVOTO
    • The angle of the device to the AV also affects risk of LVOTO
    • Size of ventricle affects how much room there is for the device
TMVI – CardiAQ (Edwards Lifesciences)x0000_cardiaq_transcatheter-mitral-valve-implantation-tmvi-device-copy
  • Bovine pericardial trileaflet valve with intra-annular sealing skirt to minimise PVL
  • Mostly sits in the LA to avoid risk of LVOTO
  • Transeptal & transapical delivery
  • Steps: Leaflet capture, vale delivery, valve expansion
  • Used in 8 patients so far with good success rate, reduction of MR to trace/none, low gradient, trace/no PVL
  • Currently undergoing FDA early feasibility study & CE mark study
  • http://circinterventions.ahajournals.org/content/8/7/e002135.extract
TMVI – FORTIS Valve (Edwards Lifesciences)x0000_edwards_fortis-transcatheter-mitral-valve-copy_0
TMVI – Tiara Valve (Neovasc Inc)
  • D shaped valve, anterior portion faces the aortic valve
  • Steps: atrial skirt deployed first, device is centred & orientated, then ventricular skirt deployed
  • Used in 7 patients in Canada in special access scheme with good success
  • Currently undergoing the TIARA-I early feasibility study
  • http://www.ncbi.nlm.nih.gov/pubmed/25256324
TMVI – Tendyne Valve (Tendyne)
TMVI – HighLife Procedure
  • 2 step procedure:
    1. Sub-annular ring implantation
    2. Valve-in-ring implantation
  • All chordae should be caught in the ring
  • Ventricular part delivered first, then whole valve is pushed up into the annulus, then atrial part delivered
  • Transapical or transatrial delivery
  • Self centuring & self positioning on release
  • First in man planned for next month
Tricuspid valve repair
  • The TV tends to dilate in the anterior & posterior leaflet direction (I.e not in the septal leaflet direction)
  • Bicuspidation of the tricuspid valve technique
    • Mattress sutures from the mid point of the posterior leaflet to the mid point of the septal leaflet
    • No difference in survival compared to annuloplasty
  • Mitralign transcather device for tricuspid annuloplasty
    • Insertion made using RF
    • First insertion make around the posterior-septal commisure
    • Device is sinched down 2 plegetted sutures & creates annuloplasty
    • Max distance to sinch (I.e between sutures) is 2.8cm – the tricuspid annular tissue is more fragile than mitral annular tissue, & any more distance could be damaging
    • Makes the posterior leaflet redundant
    • Used in 10 patients worldwide
  • Tricuspid valve repair using extra cellular matrix cylinder

 

Heart Failure Surgery

Heartmate III CE mark trial
  • Uses Maglev technology to magnetically suspend the impeller (no hydrodynamic or mechanical bearings) – allows for wide range of flow, artificial pulse (hopefully less aortic insufficiency, blood stasis, fewer GI bleeds), more consistent pump gaps (hoping to reduce haemolysis & thrombosis)
  • First in-human trial, prospective, non-randomised, n=60
    • Mean age 59yrs, ischaemic aetiology in 44%
    • All implants via median sternotomy
    • Drive line externalised with silicone to skin interface in 96% (designed to reduce infection)
    • 42% had concomitant procedures (valve operations, PFO, LAA occlusion)
    • mean CPB time 84min (63-110)
  • 30 day outcomes
    • Bleeding 30%
      • Quite high due to strict definition (≥4 units in first 7 days, ≥1 unit after day 7)
      • 12% required reoperation
    • Stroke 4% – 1 patient had difficulty engaging inflow conduit; 1 ischaemic stroke from anaphylactic shock
    • 8% right heart failure (2 requiring RVAD support)
    • No device malfunction, thrombosis, haemolysis
    • 98% survival (1 death in the ischaemic stroke patient)
  • 6 month endpoint also met, awaiting CE mark approval
  • In Viena (where study was) as soon as CE mark they will stop implant Heartmate II & only use III

Lavare cycle in the HeartWare HVAD
  • Lavare cycle involves periodic speed modulation which may reduce blood stasis
  • Lower speed (-200rpm) for 2 sec, then higher speed (+200rpm) for 1 sec, then baseline for 60sec, then cycle starts again
  • Step 1 – large vortex results in ventricular washout
  • Step 2 –
  • Step 3 – large ventricular washout again then normalised flow
  • ReVOLVE registry (n=248) analysis of the Lavare cycle
    • Significantly fewer stroke, sepsis, RHF
    • Other outcomes including survival were similar
  • Usually turned on after the patient leaves the OR (in Vienna)
Novel inflow cannula implant technique
  • LVAD results in servely disrupted blood flow in the LV – bloods flows to the ventriclar apex instead of the AV valve, increasing the risk of thrombosis
  • Study used an ex vivo dilated porcine heart (non-beating) on ECMO 4.5L
    • A cone shaped prosthetic tube was attached to the mitral valve annulus to funnel blood directly into the LVAD & avoid the disturbed flow in the LV
    • Resulted in higher flow rate & more streamlined elliptical shaped flow
  • Acute live animal experiment – successful implanted & weaned off CPB (onto VAD only) (animal had to be terminated at 1 hr due to ethics)
  • Next step is chronic animal model
LVAD less invasive approaches
  • Upper hemi-sternotomy + left thoracotomy approach possible
    • Helps preserve sternum for later heart transplantation
  • Alternative to hemi-sternotomy is right thoracotomy or right parasternal incision
    • Disadvantage is the outflow graft has to cross the midline twice as it travels to aorta
    • Disadvantage is more difficult access
    • Advantage is sternum is even further preserved for heart transplantation
  • Related paper: Maltais et al. ACS 2014

 

Minimally Invasive Mitral Valve Surgery

Debate for sternotomy approach – David Adams, Mount Siani Medical Center, NY
  • Achieving 100% repair rate with no residual regurgitation is the most important priority
  • Some studies of the mini-thoracotomy approach have compromised repair rate or an increased rate of residual MR (3 or 4+) post repair
  • Handling complexities such as annular calcification is much more difficult through a mini-thoracotomy
  • To achieve good outcomes with mini or robotic mitral surgery you need to be at a super-high volume centre, which most places are not
  • Meta-analyses have found increased rate of stroke, possibly due to retrograde perfusion from femoral CPB cannulation
  • Limited sternotomy is not as morbid as the traditional full sternotomy but provides the same full open access, & has smaller incision with good cosmesis
Debate for minimally invasive approach – Patrick Perier, Herz und Gefäß Klinik, Germany
  • Mini-thoracotomy with direct vision still requires rib spreading which is still morbid & not as ‘minimally invasive’ as possible – so it should be done as port-access surgery with video vision
  • The exact same repair techniques should be replicated with the mini-thoracotomy approach
  • New programs need to be highly selective of simple patients at the beginning, then progressively add more complex repairs & concomitant procedures (e.g. AF) as they gain experience
Evidence on mini-mitrals – J Grau, Cleveland Clinic, USA
  • Paper: Bolling et al. ATS 2010
    • Minimum of 40 mitral operations per surgeon per year are needed to achieve an 80% repair rate (deemed minimum acceptable rate)
  • Paper: Holzhey et al. Circulation 2013
    • Learning curve for minimally invasive approach at very high volume centre (Leipzig) was 150-200 patients
    • Learning curves are surgeon-specific as well, & some required re-mentoring
    • Minimum of 50-100 mini-mitrals per year are needed to be proficient
    • Very difficulty achieving this number as you need to be an expert in MV repair first, then expert in minimally invasive approach
Robotic-assisted mitral valve surgery

 

 

Sutureless Aortic Valve Replacement

Intuity valve (Edwards)
  • MIS AVR meta-analyses:
  • Intuity valve – essentially a Magna Ease valve (Edwards) combined with stainless steal stent & sealing cloth from the Sapien 3 valve
  • CADENCE MIS trial http://www.ncbi.nlm.nih.gov/pubmed/25441065
    • Intuity valve via upper hemi-sternotomy (n=51) vs. standard AVR via full sternotomy (n=49)
    • 3 conversions to full sternotomy with scented bioprostheses – 2 unable to fit valve properly, 1 annulus tear
    • 24% relative reduction in XC time (despite mini-incision, which usually increases XC time by 16%)
    • mortality not significantly different
    • PPM rate not significantly different, despite stent extending lower into the ventricle. Percival valve (similar sutureless valve) has higher PPM rate, but study had higher mean age than CADENCE-MIS (78 vs. 73), which may account for difference?
    • increased rate of mild PVL – potentially due to improper sizing, not aggressively debriding annular calcification
    • Intuity had significantly better EOA & gradients
Management of small aortic annulus
  • retrospective study comparing stented valves, Manougian procedure, stentless Freestyle prosthesis, & sutureless Percival S valve in patients with annulus <21mm
    • stentless group had significantly lower mean aortic gradient & higher EOA than other groups
      • this was a full root replacement with Freestyle graft, allowing for a larger prosthesis than the annulus
    • the Trifecta valve (St Jude) had significantly lower gradients & higher EOA than perimount, magna ease & mitroflow prostheses
Timing of individual steps in SAVR
  • aim to identify specific steps where time could be saved
    1. exposure (stating after XC + AV assessment) – 5.3mm (10min)
    2. resection (resection of AV leaflets + annulus decalcification + sizing) – 8.1mm (16%)
    3. suturing – 17.3mm (33%)
    4. tying – 9.1min (18%)
    5. declamping – 11.9min (23%)
  • sutureless valves & knot tying devices have potential to significantly reduce time
  • more experienced surgeons were faster

About The Author

Michael Seco

Dr Michael Seco is a Cardiothoracic Surgery Registrar at Royal Prince Alfred Hospital, Sydney, Australia. He has research interests in minimally invasive adult cardiac surgical techniques, including robotic-assisted coronary artery bypass grafting, transcatheter aortic valve implantation, and off-pump surgery. Dr Seco also builds and develops large scale databases used to perform clinical studies.

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