Reconstruction of the tricuspid valve should be guided by the same basic principles described for the mitral valve—that is, preserving or restoring normal leaflet motion, ensuring a large surface of leaflet coaptation, and remodeling the dilated and deformed annulus.
The three fundamental principles of tricuspid valve reconstruction are:
- 1.
Restore or preserve full leaflet mobility.
- 2.
Provide a large surface of leaflet coaptation.
- 3.
Remodel and stabilize the annulus.
APPROACH AND INTRAOPERATIVE VALVE ANALYSIS
Different types of right atriotomy have been described to expose the tricuspid valve ( Fig. 19-1, a ). The classic incisions are either a vertical or a horizontal atriotomy. Our preferred incision is a semicircular atriotomy circumscribing the implantation of the inferior vena cava cannula (b) because it minimizes injury to the conduction pathways and provides more direct visualization of the tricuspid valve. Once the atrium has been exposed, it is carefully inspected to detect endocardial thickening, thrombus formation, or jet lesions. Jet lesions are important as they indicate leaflet prolapse opposite to the jet or restricted leaflet motion on the side of the jet. The interatrial septum is carefully inspected to detect a patent foramen ovale, which could be the cause of paradoxical emboli. The tricuspid valve is then examined to detect valvular lesions. The tricuspid annulus is measured, comparing its size with the surface area of valvular tissue in order to assess the presence and severity of annular dilatation. Significant annular dilatation compared to the surface area of the leaflet tissue and organic lesions, irrespective of the size of the annulus, require reconstructive valve surgery. A systematic analysis of the three leaflets using nerve hooks and the functional classification guide the techniques to be used ( Fig. 19-2 ).
PALLIATIVE ANNULOPLASTY TECHNIQUES
Several annuloplasty techniques have been used in the past to correct tricuspid valve dysfunctions ( Fig. 19-3 ). Since the predominant lesion was a severe dilatation of the tricuspid annulus, the goal of these techniques was to excessively narrow the orifice to achieve leaflet coaptation (a-e) . Although acceptable early results were obtained, long-term results were marred by recurrent regurgitation or stenosis. The introduction in 1968 of the annular remodeling concept to the mitral valve was soon applied to the tricuspid valve (e) , providing reliable and stable long-term results. One year later, de Vega proposed an annuloplasty using a single or double circular suture (e) , which had the advantage of not using prosthetic material but the inconvenience of being a narrowing annuloplasty and not restoring a normal shape to the annulus.
TYPE I TRICUSPID REGURGITATION
Annular Remodeling
Type I regurgitation due to annular dilatation is best treated by annular remodeling. The prosthetic ring used for tricuspid valve annuloplasty differs from the ring designed for mitral annuloplasty ( Fig. 19-4, a-b ). It has an oval shape, which replicates the systolic configuration of the normal tricuspid orifice. The “Classic ring” model consists of a short linear segment corresponding to the septal leaflet and a long, curved segment corresponding to the anterior and posterior leaflets (a) . The Classic ring is a cloth-covered titanium semirigid structure with maximal flexibility in the axial dimension (b) . This flexibility allows the ring to adapt to the natural but variable helicoidal configuration of the tricuspid annulus. A slight outward bending of the anterior and inward bending of the septal end of the ring manually before lowering it into position facilitates this adaptation. Using magnetic resonance imaging and extensive anatomical studies on beating hearts, a Physio ring has been designed (c-d) . The “wave form” contour and selective flexibility of the different segments of this ring adapt to the complex motion of the annulus. This reduces the stress on the anatomical structures and therefore minimizes the risk of arrhythmia and ring dehiscence. Optimized ring dimensions are indicated in Table 19-1 .
| Ring size (mm) | 26 | 28 | 30 | 32 | 34 | 36 |
|---|---|---|---|---|---|---|
| Transverse diameters: | ||||||
| External (mm) | 31.2 | 33.2 | 35.2 | 37.2 | 39.2 | 41.2 |
| Internal (mm) | 24.3 | 26.3 | 28.3 | 30.3 | 32.3 | 34.3 |
| Orifice area (mm 2 ) | 310 | 364 | 423 | 486 | 553 | 626 |
Ring Selection
The size of the prosthetic ring is chosen according to the surface area of the leaflet tissue . This is assessed by two measurements ( Fig. 19-5 ): (1) The first is the measurement of the base of the septal leaflet, which is not significantly affected by annular dilatation (a) . To facilitate this measurement, a suture is placed at the posteroseptal commissure (b) . Each sizer has two notches at its septal segment that are used to measure this annular segment. One notch should correspond to the anteroseptal commissure and the other to the suture placed at the posteroseptal commissure. (2) The second and most important measurement is the surface area of the leaflet tissue attached to the chordae arising from the anterior papillary muscle (c) . Traction is exerted with a right angle clamp on all the chordae arising from the anterior papillary muscle so as to expose the leaflet tissue attached to these chordae. This comprises a large portion of the anterior leaflet and a small portion of the posterior leaflet. The sizer selected from the first measurement is used to cover the portion of the exposed leaflet tissue (d) . If the surface area of the leaflet tissue is less than that of the preselected sizer, a smaller sizer should be tried and vice versa . The measured leaflet surface area indicates the optimal orifice area and therefore the size of ring to be selected.
The size of the ring is selected from the surface area of the leaflet tissue, not from the annular circumference.
Ring Implantation
Once the ring has been selected, a series of 3-0 horizontal mattress sutures are placed at equidistant points around the tricuspid annulus. To place these sutures properly within the annulus, the leaflet tissue must be grasped transversally and pulled away from its attachment to visualize its hinge ( Fig. 19-6 ). The first septal suture should be placed posterior to the midline of the septal leaflet attachment, through the very hinge of this leaflet to prevent injury to the bundle of His. The following septal mattress suture is placed in the same manner towards the posteroseptal commissure. Directing the needle through the annulus toward the ventricular cavity and then back through the annulus ensures that these bites have maximal strength. The mattress sutures corresponding to the posterior and anterior leaflets are placed within the annulus (i.e., 2 mm from the atrio-valvular junction) ( Fig. 19-7 ). A schematic rectangular presentation of the annulus illustrates the commonly used needle maneuvers and positions. For the two horizontal sides backhand sutures are used and forehand sutures for the two vertical sides. In the aortic segment of the annulus, special care should be taken not to injure the aortic root. This can be achieved by visualizing the hinge of the anterior segment and by placing suture with the tip of the needle always oriented towards the right ventricle . Sutures are then passed through the sewing band of the selected ring ( Fig. 19-8 ); equal spacing is used for sutures of the septal leaflet (a) while reduced spacing is used for sutures that arise from the posterior and anterior leaflets, especially for those arising from the commissures ( b-d ). The relative flexibility of the ring allows its adaptation to the three-dimensional configuration and complex motion of the annulus.
