MS 12 - Transcatheter aortic valve implantation (TAVI)
1. To understand the clinical needs of non-surgical techniques for aortic valve replacement.
2. To understand the difficult process of developing a breakthrough innovative technology in interventional cardiology.
3. To understand the importance of “translational research” for the success and expansion of TAVI.
Aimed at redressing the limitations of balloon aortic valvuloplasty developed by our group in 1985 for the treatment of inoperable patients with aortic stenosis (AS), TAVI (transcatheter aortic valve implantation) emerged in 2002 to profoundly alter the landscape of cardiovascular medicine. This new disruptive technology is among the important “medical breakthroughs” till date. It evoked scepticism and criticism in the beginning. But, thanks to innumerable clinical trials and evidence-based investigations, it is widely accepted by the medical community now and this acceptance is continuing to grow. In the last decade, TAVI has been performed in about 300 000 patients around the world and its use keeps growing 40% annually. The field of TAVI is rapidly evolving, with major refinements in technology and procedural techniques, patient selection and biomedical engineering.With the development of better devices, new approaches and new implantation strategies, TAVI has become much simpler and safer. The indications were initially limited to elderly AS patients with multiple co-morbidities. The same are now cautiously and appropriately growing to include a broader population of patients with lower surgical risk and degenerated surgical bioprosthesis. There are few examples of clinical fields in medicine that match the rapid and careful evolution of TAVI.
1. To learn the current indications of TAVI and the process of patient selection.
2. To learn the different phases of the procedure using the transfemoral approach.
3. To learn the prevention and treatment of complications.
In 2016, TAVR is clearly turning into a routine procedure. This is driven by a number of factors: increased operator’s experience, better patient selection and improved 3D adjunctive imaging. But, mainly, striking technology enhancements have changed the world of TAVR with improved systems, and the development of “minimalist strategies” making the procedure faster, simpler safer and more cost-effective. In 2016 was demonstrated the efficiency of new devices provided by the two leading companies, Edwards Lifesciences with its balloon-expandable Sapien 3 valve, and Medtronic with its self-expanding Evolut-R valve. With these new devices, the main complications of TAVR, mortality, paravalvular regurgitation (PV), vascular complications and stroke have been considerably improved. In the US, PARTNER Sapien 3 trial reported this year (583 patients), all cause mortality has decreased at 1 month to 1.1% (13% at 1 year), disabling stroke to 1.0%, PV leak to 3%, major bleeding and vascular complications to 5%. Similar improved results with the Evolut-R in a smaller series of patients were reported. In 2016, with the decreased size of the new devices, TAVR can now be performed using the transfemoral approach (the default access site) in almost 90% of cases, under local anaesthesia, allowing early discharge home within 3 days in a majority of cases (60% in Rouen). In patients non-suitable for transfemoral approach, alternative approaches include trans-aortic, trans-apical, trans-carotid and subclavian routes. TAVR is confirmed to be a breakthrough technology addressing an unmet clinical need validated by rigorous evidence-based studies.
1. To learn the different mini-surgical approaches for TAVI and the current indications.
2. To learn the different phases of TAVI using the mini-surgical approaches.
3. To learn from a cardiac surgeon the perspectives of surgical valve replacement in the TAVI era.
During many years, the only treatment of calcific aortic stenosis was surgical aortic valve replacement. Despite excellent results, numerous patients were not eligible to surgery due to comorbidities or frailty. In April 2002, the first human transcatheter aortic valve implantation(TAVI) was performed in Rouen leading to a new era in the treatment of aortic stenosis. The first cases of TAVI were performed with a surgical cut down of the groin under local anaesthesia. But, due to the large diameter of the first catheters (24Fr) and the presence in numerous patients of small calibre vessels, the idea of a transapical approach emerged and, the first patients were implanted in 2005. Few years later, new surgical approaches were developed with transaortic, trans-sub-clavian or transcarotid artery procedure. Transapical approach could be a secure procedure if a perfect analysis of the aortic valve is managed prior to surgery to avoid drastic complication. The measurement of the distances between annulus and coronary ostia, the aortic valve area and the annulus plan are the key points of procedural success. At the beginning of the procedure, a transthoracic echocardiography to determine the position of the apex of the heart is strongly recommended. Multiple studies have reported excellent results whatever the approach (transfemoral, transapical, etc.) and the initial goal, i.e. “to provide an alternative to non-surgical patients” has been reached. However, the long-term durability of the transcatheter valves still unknown and today, the use of TAVI in low risk or younger patients remains controversial.
1. To learn about the technical principles of MDCT acquisition in pre-TAVI assessment.
2. To learn about the advantages of a structured MDCT report (including key images) validated by the cardiology team.
3. To know the medical impact of the radiology team in the management of TAVI patients.
In recent years, transcatheter aortic valve intervention (TAVI) gained wide acceptance in patients with severe aortic stenosis contraindicated to surgical valve replacement. Pre-operatively, CT of the heart, aorta and iliac vessels is recommended. Various CT techniques can be performed depending on CT generation. Basically, ECG-gated examination of the heart and aortic root should be performed, completed by non-gated coverage of the abdominal aorta and ilio femoral vessels. Systolic reconstruction of the heart should be obtained to evaluate the aortic valve area and measure the annulus (diameters and planimetry). Diastolic reconstruction can be used for evaluating distances between annulus and coronary ostia, the sub-aortic septum, the calcification and cuspidity of the valve, the extent of the calcification (i) to the annulus (increasing the risk of per procedural rupture) (ii) to the septum (risk of conduction abnormality) and (iii) mitral valve. Vascular route should be evaluated from the access up to the aortic valve. All images should be transmitted to the Cath. Lab. with a structured report, including any other thoraco-abdominal abnormality/disease, a frequent situation is those elderly patients.
1. To know how to decrease the dose of iodine with new CT technology including dual-energy.
2. To know how to control the radiation dose with new CT technology.
3. To know how to characterise the myocardium with new CT technology.
Since the first introduction of transcatheter aortic valve implantation (TAVI), the number of procedures has increased worldwide. A comprehensive cardiac and aorto-iliac arteries CT angiography before the procedure has become a common and recommended clinical practice. Dual-energy CT (DECT) allows to quantify iodine within a voxel and to display two different data sets : (1) virtual monoenergetic images and (2) Iodine maps. The virtual monoenergetic images allow to increase iodine attenuation at post-processing hence to reduce the injected iodine load. This property is of importance in TAVI population with frequent impaired renal function. Up to 50% reduction of iodine volume can be attained at the expense of an increased image noise which remains acceptable for diagnosis. The iodine maps allow to measure iodine concentration within a voxel. Myocardial extracellular volume fraction (ECV) is a validated myocardial fibrosis marker; it is directly measurable from iodine maps. The ECV calculated from DECT is comparable and/or highly correlated to ECV calculated from MRI. A single delayed post-contrast DECT acquisition could add a prognosis value to the actual standard anatomic comprehensive CT evaluation.