Primary (leaflet abnormality): 25%
Congenital
Ebstein’s anomaly
Tricuspid valve tethering associated with perimembranous VSD and VSA
Other (giant right atrium)
Acquired disease
Carcinoid
Degenerative (myxomatous)
Endocarditis
Endomyocardial fibrosis
Iatrogenic (pacing leads, RV biopsy)
Rheumatic
Toxins
Trauma
Other (e.g., ischemic papillary muscle rupture)
Secondary (functional): 75%
Left heart disease
LV dysfunction or valve disease
Right ventricular dysfunction
RV cardiomyopathy (e.g., ARVD) RV ischemia
RV volume overload
Pulmonary hypertension
Chronic lung disease
Left-to-right shunt
Pulmonary thromboembolism
Right atrial abnormalities
Atrial fibrillation
Other
Post-operative
Recurrent TR post-surgical intervention
Right heart catheterization is important for determining the etiology of secondary TR. Evaluating both the degree and origin of PAH (pre-capillary, isolated post-capillary, or combined pre- and post-capillary) [7] impacts the decision to treat or not to treat severe functional TR. Interventions in patients with pre-capillary PAH or severe PAH may be associated with major negative clinical effects secondary to critical RV failure. Similarly, an early post-operative RV dysfunction after tricuspid surgery has been associated with a negative clinical outcome [5].
Outcomes
Significant secondary TR is frequently well tolerated in its early stages, however, progressive dilation of the tricuspid annulus and RV remodelling results in right heart failure over time. Irreversible RV damage is a common reason for the poor outcomes following late TV surgery.
Several observational studies have reported that moderate-to-severe TR is associated with excess mortality at follow-up, independent of RV function [8, 9]. It is important to optimize medical therapy of the underlying condition according to guidelines. The use of pulmonary vasodilator therapies in post-capillary PAH is not recommended in patients with PAH secondary to left heart disease according to the 2015 European guidelines [7].
Surgery for TR
In patients with severe mitral regurgitation and normal left ventricular ejection fraction, the prevalence of at least moderate TR was 24% [10]. Following mitral valve surgery in case, this has not been combined with tricuspid repair in the presence of an annulus diameter of >40 mm, nearly 50% of the population demonstrated an increase in TR severity of more than two grades over time [11].
Despite the association of severe TR and poor survival, relatively few patients undergo TV surgery. In the absence of another indication for cardiac surgery patients are mostly managed with medical therapy. Isolated TV surgery accounts for only 20% of all tricuspid interventions [12], mostly because this is associated with a high operative risk. Results from isolated TV surgery series report an in-hospital mortality rate ranging from 2% to 9.8% [12–14]. Pre-operative hemoglobin, bilirubin, creatinine levels, and measures of RV function predicted clinical outcome [15].
In patients undergoing left-sided valve surgery, the guidelines (Fig. 15.2) recommend concomitant TV repair when the tricuspid annulus is dilated, even if TR severity is mild [16, 17]. This is done to prevent the need for TV reoperation at a later date, if severe TR and RV dysfunction develop. Tricuspid annuloplasty remains the surgical technique of first choice for functional TR, either by suture annuloplasty or ring annuloplasty, which is the currently preferred technique due to increased durability compared with suture techniques [18].
Transcatheter Interventions for TR
In recent years novel transcatheter interventional options were developed for treating TR. Patients with severe TR and prior open-heart surgery are often deemed at high or prohibitive operative risk for reoperation and are mostly treated medically. In particular, those patients and patients with functional TR and progressive RV dysfunction with right heart failure are candidates for less invasive transcatheter techniques.
When performing transcatheter interventions for TR the size of a device and its placement into the RA or RV should take into account close structures that can be injured by the procedure, such as the AV node, the coronary sinus, and the right coronary artery. Pacemaker or defibrillator leads, which may cause significant TR [19] could also impact the feasibility of a transcatheter technique. To date, this has been a contraindication for most of the transcatheter TV repair techniques.
Imaging of the Tricuspid Valve
Several catheter techniques for functional TR are currently under clinical evaluation. For the application of all these devices imaging is crucial. Most of the procedures are almost completely guided by transesophageal echocardiography.
Because visualisation of the tricuspid valve for guiding transcatheter procedures is a new field, a brief introduction into this specific issue seems to be reasonable.
Transthoracic Echocardiography
Visualizing the TV should be performed from multiple transthoracic windows (Fig. 15.3a–d). The European and American Heart Association/American College of Cardiology guidelines recommend the end-diastolic septolateral dimension from the transthoracic apical 4-chamber view (Fig. 15.3c) as a criterion for intervening. A dimension of 40 mm (or >21 mm/m2) indicates severe tricuspid annular dilation [16, 17].
Fig. 15.3
Transthoracic and transesophageal imaging planes for the TV. Multiple transthoracic imaging planes (a–d) should be performed for comprehensive imaging of the tricuspid valve (TV). The parasternal inflow view.(a) Images the anterior (a) and posterior (p) leaflets when no ventricular septum is in the imaging plane. (b) Parasternal short-axis view at the level of the aortic valve; when the transducer is angled anteriorly, only the anterior (a) leaflet is seen (with no other leaflet coaptation). (c) On-axis 4-chamber view with the left ventricle (LV) in the apex of the sector. The end-diastolic frame shown should be used to measure the annular diameter (dashed yellow double arrow). A subcostal view is shown in d. Transesophageal imaging planes (e–g) should be performed from multiple levels. These examples from the mid-esophageal view (e), the deep-esophageal view (f), and the transgastric view (g) are simultaneous multiplane images showing the primary imaging plane on the left of each panel, and the orthogonal (rotated 90°) image on the right side of each panel. AV ¼ aortic valve; LA ¼ left atrium; RA ¼ right atrium; RV ¼ right ventricle; RVOT ¼ right ventricular outflow tract; s ¼ septal leaflet
Table 15.2 summarizes the parameters used for grading the severity of TR, which are described by the ASE and European Association of Echocardiography guidelines [20, 21]. Quantitative assessment of tricuspid regurgitant volume by the proximal iso-velocity surface area method has been validated [22, 23]. An effective regurgitant orifice area (EROA) >40 mm2 and regurgitant volume of >45 mL has been considered an important sign of severe TR. Three-dimensional (3D) imaging studies of the color Doppler vena contracta, however, suggest that severe tricuspid regurgitation EROA may be >75 mm2 [24, 25].
Table 15.2
Assessment of TR severity
Parameters | Mild | Moderate | Severe |
|---|---|---|---|
Qualitative | |||
TV morphology | Normal or mildly abnormal leaflets | Usually abnormal leaflets | Severe valve lesions (e.g., flail leaflet, severe tethering, malcoaptation) |
Interventricular septal motion | Normal | Typically normal | Paradoxical/volume overload pattern (diastolic interventricular septal flattening) |
Colour flow TR jet (note: not recommended for sole grading of severity) | Small RA penetration or not holosystolic | Moderate RA penetration or large penetration and late systolic | Deep RA penetration and holosystolic jet, or eccentric wall-impinging jet (variable size) |
Flow convergence zone | Not visible, transient or small | Intermediate in size and duration | Large throughout systole |
CW TR jet density/contour | Faint/parabolic or partial contour | Dense/parabolic, variable contour | Dense/triangular with early peaking (peak <2 m/s in massive TR) |
IVC size | Usually normal | Usually normal or mild dilation | Usually dilateda with reduced respirophasic variability |
RV and RA size | Usually normal | Usually normal or mild dilation | Usually dilatedb |
Semi-quantitative | |||
Tricuspid annulus | <40 mm2 or 21 mm2/m2 | May be >40 mm2 or 21 mm2/m2 | >40 mm2 or 21 mm2/m2 |
‡Color flow jet area (cm2) | Not defined | Not defined but <10 | >10 |
‡ Vena contracta width (mm) | Not defined | <7 | ≥7 |
§PISA radius (mm) | ≤5 | 6–9 | >9 |
Hepatic vein flow | Systolic dominance | Systolic bluntingc | Systolic flow reversal |
Tricuspid inflow | A-wave dominant and/or E-wave <1 m/s | Variable | E wave dominant (≥1 cm/s) |
Quantitative | |||
EROA (mm2) [by PISA] | <20 | 20–39d | ≥40 |
Regurgitant volume (mL) [by PISA] | <30 | 30–45d | ≥45 |
Transesophageal Echocardiography
Compared to transthoracic, transesophageal echocardiography (TEE) has higher spatial resolution and allows a larger number of windows to image the entire TV apparatus. The new ASE guidelines [26] advocate additional views of the TV (Fig. 15.3e–g). Low esophageal and high transgastric views may permit better imaging of the TV. Transgastric short-axis views allow simultaneous visualization of all valve leaflets (Fig. 15.3g, orthogonal plane). A deep transgastric view of the TV permits optimal color flow and spectral Doppler evaluation of TR jets.
Three-D imaging of the TV, which has also been addressed in the guidelines [27] has significantly improved the identification of the tricuspid leaflets and associated anatomic components.
Lang et al. [27] suggested a standardized imaging display for the en face view of the TV with the interatrial septum placed at the 6 o’clock position (Fig. 15.4). This standardization improves the communication with the interventionist when performing transcatheter interventions.
Fig. 15.4
3D Imaging of the TV. The surgical view of the tricuspid valve (TV) (a) places the interatrial septum inferiorly (at the 6 o’clock position), regardless of the atrial or ventricular orientation. Using 3-dimensional (3D) color Doppler (b), the effective regurgitant orifice area can be used to quantify the severity of regurgitation. TR ¼ tricuspid regurgitation
Transcatheter Treatment Modalities
Interventional strategies for functional TR comprise three different types of approaches (Fig. 15.5):
Transcatheter valve implants at the level of the SVC and IVC or the IVC only, to treat the caval reverse backflow.
Devices to improve valve leaflet coaptation by occupying the regurgitant orifice area (FORMA device) or by edge-to-edge repair (Mitraclip device).
Devices to decrease the TA dimensions in order to reduce TR severity (Trialign, TriCinch, CardioBand). As preclinical upcoming devices, TRAIPTA and the Millipede IRIS Implant.
Fig. 15.5
Transcatheter treatment modalities
Bicaval Valve Implantation
Due to the challenging anatomy of the TV complex, there is a lack of in-human experiences of transcatheter TV replacement. However, experience with valve implantation for treating TR has targeted the inferior and superior vena cava in order to limit the reverse backflow associated with severe TR.
Caval valve implantation (CAVI) has been suggested for patients with severe TR and significant regurgitation of blood into the caval veins, which is often seen in the presence of severe, long- standing TR and RV enlargement. The main challenges for this approach are the large and variable diameter of the caval veins and the proximity of the right atrium and hepatic veins.
Self-expandable dedicated Valve devices: Self-expandable dedicated valve devices are currently under clinical evaluation for a transvenous approach (Fig. 15.6a–e) [28]. The Tric Valve (P&F Products & Features Vertriebs GmbH, Vienna, Austria, in cooperation with Braile Biomedica, São José do Rio Preto, Brazil) consists of two self-expandable bio-prosthetic valves that are anchored at the cavo-atrial inflow accommodating vein sizes from 28 to 43 mm. These self-expandable devices do not require a pre-stenting of the caval veins. They are designed with the upper segment protruding into the RA, to protect from backflow and, on the other hand, avoid occlusion of hepatic veins [28, 29].
Fig. 15.6
CAVI with the Tric valve device . (a and b) The pericardial valve mounted on a self-expandable nitinol stent is loaded into a 27-F catheter for implantation. (c–e) After transfemoral access and under fluoroscopic and echocardiographic guidance, the SVC and IVC valves are sequentially deployed. Transjugular pacer leads are jailed by the SVC stent. Reprinted with permission from Lauten et al. [29]. (f and g) Pressure measurement confirms a reduction of the ventricular wave and mean pressure in IVC pressure from 32 mm Hg to 23 mm Hg and 24 mm Hg to 19 mm Hg, respectively. Blue tracing ¼ inferior vena cava; red tracing ¼ right atrium. CAVI ¼ caval valve implantation; IVC ¼ inferior vena cava; SVC ¼ superior vena cava
Chronic animal studies further showed excellent function of caval valves at midterm follow-up [30]. Since 2011, five compassionate clinical use cases have been performed confirming the technical feasibility of CAVI, as well as the immediate and sustained hemodynamic improvement from the reduction of IVC and SVC backflow (Fig. 15.6f, g) [28]. The device was implanted successfully in four cases. In one patient, the devices could not be deployed as intended, and surgery was required. After a mean clinical follow-up of 7.4 ± 13.2 months, sustained valve function was observed. Midterm symptomatic relief and moderately improved physical capacity were observed [28, 29]. Warfarin anticoagulation was effective and sufficient to prevent thromboembolic complications during follow-up. However, the mortality rate was 80%, which reflects the significant comorbidities of this patient cohort. A prospective multicenter registry is planned in the near future.
Balloon-expandable caval implants: Caval implantations of balloon-expandable valves designed to treat aortic stenosis (29 mm Edwards Sapien XT or Sapien 3, Edwards Lifesciences, Irvine, California) have also been used off-label for the treatment of severe TR. Due to size limitations this approach requires preparation of a landing zone by implanting one or more self-expandable stents (Sinus XL, Optimed Medizinische Instrumente, Ettlingen, Germany), to facilitate valve fixation. This technique has been mostly limited to the IVC.
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