Overtchouk P, et al. BMC Cardiovasc Disord. 2020 Jan 7;20(1):1.
Overtchouk P, et al., conducted a review to provide a descriptive review of the published literature on transcatheter mitral and tricuspid interventions.
Transcatheter mitral valve therapies
Percutaneous mitral commissurotomy (PMC) for rheumatic mitral stenosis
PMC is potent and has less procedural morbidity and mortality vs. open surgery, also stores the opportunity to interfere in the condition of reoccurrence. While eligibility standards for PMC are precise and if absent then open surgery is preferred (Table 1).
Table 1: Characteristics of unfavourable anatomy for percutaneous mitral commissurotomy
Edge-to-edge transcatheter mitral valve plasty
Devices developed for transcatheter therapy of mitral regurgitation (MR) have frequently been encouraged by surgical techniques. Therefore, transcatheter-based tools can be arranged into replacement and repair approaches.
The MitraClip (MC) tools lead from the modification of the surgical Alfieri valvuloplasty at the initiation of the century. Since then, the clipping tools go through various replications (NT, NTR, XTR) which enhances its size, desirous and mobility. Composed of cobalt-chromium wrapped with polyester, the implant consists of two arms which helps to capture the two leaflets and is supplied transseptally. It decreases the mitral regurgitation orifice by “tying” them collectively. Several clips can be located to optimize outcomes.
The Pascal™ (Edwards Lifesciences) edge-to-edge mitral plasty tool is a movable and retrieval system. This tool has two paddle-shaped holding arms that are separately sealable (clasps) as well as a basic divider that is designed to fill the regurgitant jet area.
Following favourable early incidents for compassionate use, PASCAL has been estimated to be safe and potent adequate for clinical practice in the CLASP prospective multicenter cohort study. Almost 62 participants have been involved in the CLASP cohort, with both regressive and functional MR, and lower rates of cardiovascular mortality 1.6% was found, hardly any stroke occurrences and a 98% grade of < 3+ MR at 30 days (Table 2, Figure 1).
Table 2: Baseline markers of congestion as a function of all-cause mortality
Figure 1: Transcatheter mitral (a) and tricuspid (b) valve intervention devices with reported clinical use
Transcatheter annuloplasty and chordal plasty
Most updated are the transcatheter annuloplasty (such as CardioBand™, Edwards Lifesciences) and chordal replacement (such as NeoChord™ NeoChord, Inc.; or Harpoon™ Edwards Lifesciences) systems. The Cardioband is an adjustable insert with various hooks that are connected to the annulus, and when they are all set, strains can be exerted by lowering the dilated annulus to a physiological size. This tool is delivered through a flexible catheter transseptally.
Transcatheter mitral valve replacement
In the international guidelines, the mitral repair is preferred as a replacement for the open surgical treatment of MR. Although, this recommendation is adapted from experimental evidence. Current randomized evidence observed that replacement almost evacuates the chance of a long-term repetition of moderate or severe MR at 2 years (58.8% after repair vs. 3.8% after replacement). Transcatheter mitral valve replacement (TMVR) could offer a better alternative by preventing the morbidity of open mitral surgery and efficiently inhibiting the recurrence of MR.
Transcatheter tricuspid valve therapies
Transcatheter tricuspid valve intervention (TTVI) techniques prevent open surgical morbidity providing conditions such as cardio-pulmonary bypass, sternotomy, and intubation, which could enhance peri-operative survival survey and industries are recently extremely active in this area (Table 3).
Table 3: Short term (in-hospital or 30-days) outcomes of TTVI devices
Transcatheter edge-to-edge and spacer tricuspid technology
As for transcatheter mitral valve therapies, for tricuspid valve intervention, percutaneous techniques were commonly encouraged by surgical techniques. For the tricuspid valve as well as for the mitral valve, the Alfieri-styled edge-to-edge surgery has been suggested. Several experiences with the MitraClip in the mitral position induced various operators to undertake tricuspid regurgitation (TR) correction utilizing the MitraClip in the tricuspid position. The best outcomes emerge to happen by connecting the anterior and/or posterior leaflet to the septal leaflet that can also minimize annular dimensions.
Transcatheter annuloplasty techniques
The Trialign tool is a transcatheter suture annuloplasty technique conducted transjugularly. An insulated radiofrequency wire is progressed into the right ventricle and then retrogradely crosses the tricuspid annulus tissue. Henceforward, two pledgets are positioned at the posteroseptal as well as the anteroposterior joints, which are then tightened to eliminate the posterior tricuspid leaflet, producing a “bicuspidisation” of the tricuspid valve.
The TriCinch tool is supplied through the femoral vein. It shows an epicardial coil with two haemostasis seals inserted in the mid-anterior part of the tricuspid annulus, a nitinol stent linked to the coil over a Dacron band, is positioned in the inferior vena cava (IVC), to keep strain applied to the annulus.
Transcatheter tricuspid valve replacement
The NAVIGATE (NaviGate Cardiac Structures) transcatheter heart valve (THV) is a self-enhancing bioprosthesis for orthotopic tricuspid valve replacement (TTVR) which contains 3 xenogeneic pericardial leaflets located in a tapered nitinol stent with atrial winglets and ventricular graspers for supporting the tricuspid annulus and leaflets without extending into nearby chambers. NAVIGATE is provided in four sizes designed for TA diameters varying from 36 mm to 52 mm. A 42 Fr introducer sheath is used to provide the valve under a transjugular pathway (or through transatrial minimally invasive right thoracotomy surgical approach). The NAVIGATE is recently the only clinically accessible TTVR tool.
Thus, the future seems promising for transcatheter mitral therapies, whereas their position in clinical experience still has not been evidently specified. Tricuspid transcatheter therapies may resolve the existing needs of tricuspid regurgitation treatment.
