Aortic Figure 3: Proposed Algorithm for Decision-making Regarding Alternative Access Transcatheter Aortic Valve Implantation
Deciding on an Alternative Access Route
Decision made for alternative access TAVI
Heart team discussion
MDCT imaging Carotids Thoracic aorta Subclavian/axillary artery Abdominal aorta
Patient factors Previous CABG Depressed LV function Carotid artery disease Respiratory disease
Other factors Relevant local expertise Functional circle of Willis Patient preference
Decision made regarding most appropriate alternative access route based on all factors Transcarotid
Transaxillary/subclavian
Transaortic/apical
Transcaval
CABG = coronary artery bypass graft; LV = left ventricular; MDCT = multiple detector CT; TAVI = transcatheter aortic valve implantation.
the renal artery, renal vein and aorto-iliac bifurcation, as a covered stent may be required as a bailout strategy if there are bleeding complications during the procedure. A microcatheter is delivered into the descending aorta and a stiff guidewire is introduced. Once crossover is achieved, the TAVI introducer sheath can be introduced in the usual manner and the valve implanted using a retrograde approach. A nitinol cardiac occluder device is used to close the iatrogenic aortocaval fistula after valve implantation. The largest cohort, described in the literature by Greenbaum et al., consists of 100 patients who were ineligible for femoral artery access and had a high or prohibitive risk from transthoracic access.33 Device implantation was successful in 99 patients. They reported a 30-day survival of 92%, a life-threatening bleeding rate of 7% and a major vascular complication rate of 13%. While this technique has certainly been demonstrated to be feasible, it is probably best reserved for use in experienced, high-volume specialist centres at present, but may become more commonplace
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iontis GC, Praz F, Pilgrim T, et al. Transcatheter aortic S valve implantation vs surgical aortic valve replacement for treatment of severe aortic stenosis: a meta-analysis of randomized trials. Eur Heart J 2016;37:3503–12. https://doi. org/10.1093/eurheartj/ehw225; PMID: 27389906. Thyregod HG, Søndergaard L, Ihlemann N, et al. The Nordic Aortic Valve Intervention (NOTION) trial comparing transcatheter versus surgical valve implantation: study protocol for a randomised controlled trial. J Am Coll Cardiol 2015;65:2184–94. https://doi.org/10.1016/j.jacc.2015.03.014; PMID: 25787196. Natarajan D, Makkar R, MacCarthy P, et al. Placement of Aortic Transcatheter Valves (PARTNER) 2 Cohort A trial – transcatheter or surgical aortic-valve replacement in intermediate-risk patients. EuroIntervention 2016;12:805–8. https://doi.org/10.4244/EIJV12I6A131; PMID: 27542796. Barker CM, Reardon MJ. The CoreValve US pivotal trial. Semin Thorac Cardiovasc Surg 2014;26:179–86. https://doi.org/10.1053/ j.semtcvs.2014.10.001; PMID: 25527011.
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in future. A recent meta-analysis concluded that the initial evidence is encouraging but further prospective studies are probably required before any firm conclusions can be made.34
Multi-detector CT scanning plays a vital role in determining the most appropriate access route. It can give information on luminal diameter, calcific vessel load and tortuosity of the relevant vasculature. For TF TAVI, it allows practitioners to assess the iliofemoral vessels bilaterally to determine if a patient is suitable. If transcaval access is being considered, CT scanning can identify a suitable area on the right aortic wall for passage of the transcatheter aortic valve replacement sheath from the inferior vena cava to the abdominal aorta. For transcarotid TAVI, it provides valuable information on the subclavian, carotid and vertebral arteries. Imaging experts play an important role in the heart team discussion and can help guide operators toward the most appropriate access route. In general, vascular access site complications are a common cause of significant morbidity and mortality after a TAVI procedure. A key role of the heart team should be to identify the access route that will minimise this risk. If alternative access is considered, a vascular surgeon should be part of the heart team to identify potential risks associated with the access routes and assist in the decision-making (Figure 3).
Conclusion Since its inception, TAVI has undoubtedly revolutionised the treatment of aortic stenosis. Enormous strides have been made with regard to patient and device selection, pre-procedural planning and procedural simplification. This has resulted in improvements in patient outcomes and increased operator confidence with regards to taking on more complex cases. Unsuitable iliofemoral anatomy no longer precludes patients from undergoing TAVI and physicians have become more comfortable with alternative access routes. Without intervention, these patients have a poor prognosis with a mortality rate of around 50% at 2 years.35 While much of the published data on alternative access TAVI shows promising results, the majority of this is registry data rather than randomised controlled trials. TF TAVI remains the safest access route and should be considered in the majority of cases. However, in unsuitable patients, different access routes have been shown to be safe and feasible. The challenge is to choose the best alternative access route for the individual patient based on their vascular anatomy and comorbidities, choice of valve and the local institutional skill set.
eardon MJ, Van Mieghem NM, Popma JJ, et al. Surgical or R transcatheter aortic-valve replacement in intermediaterisk patients. N Engl J Med 2017;376:1321–31. https://doi. org/10.1056/NEJMoa1700456; PMID: 28304219. Medtronic Evolut Transcatheter Aortic Valve Replacement in Low Risk Patients (NCT02701283). Available at: https://clinicaltrials. gov/ct2/show/NCT02701283 (accessed 27 February 2019). Comparison of Transcatheter Versus Surgical Aortic Valve Replacement in Younger Low Surgical Risk Patients With Severe Aortic Stenosis (NOTION–2) (NCT02825134). Available at: https://clinicaltrials.gov/ct2/show/record/NCT02825134 (accessed 27 February 2019). The PARTNER 3 – Trial – The Safety and Effectiveness of the SAPIEN 3 Transcatheter Heart Valve in Low Risk Patients With Aortic Stenosis (P3) (NCT02675114). Available at: https:// clinicaltrials.gov/ct2/show/NCT02675114 (accessed 27 February 2019). Cribier A, Eltchaninoff H, Bash A et al. Percutaneous transcatheter implantation of an aortic valve prosthesis
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for calcific aortic stenosis: first human case description. Circulation 2002;106:3006–8. https://doi.org/10.1161/01. CIR.0000047200.36165.B8; PMID: 12473543. Leon MB, Smith CR, Mack M, et al. Transcatheter aortic-valve implantation for aortic stenosis in patients who cannot undergo surgery. N Engl J Med 2010; 363:1597–607. https://doi. org/10.1056/NEJMoa1008232; PMID: 20961243. Leon MB, Smith CR, Mack M, Makkar R et al. Transcatheter or surgical aortic-valve replacement in intermediaterisk patients. N Engl J Med 2016; 374:1609–20. https://doi. org/10.1056/NEJMoa1514616; PMID: 27040324. Petronio AS, Capranzano P, Barbato E, et al. Current status of transcatheter valve therapy in Europe: results from an EAPCI survey. EuroIntervention 2016;12:890–5. https://doi.org/10.4244/ EIJY16M06_01; PMID: 27283408. Ludman PF, Moat N, de Belder MA, et al. Transcatheter aortic valve implantation in the United Kingdom: temporal trends, predictors of outcome, and 6–year follow-up: a report from the UK Transcatheter Aortic Valve Implantation (TAVI) Registry,
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