Venae Cavae Anatomic Characteristics in Severe Tricuspid Regurgitation: Implications for Transcatheter Interventions

Transcatheter tricuspid valve interventions (TTVIs) are rapidly expanding with new technologies being developed and investigated to address the unmet clinical need of severe tricuspid regurgitation (TR), a condition with significant morbidity and mortality, and relatively high associated surgical risk.1Wang N. Fulcher J. Abeysuriya N. et al.Tricuspid regurgitation is associated with increased mortality independent of pulmonary pressures and right heart failure: a systematic review and meta-analysis.Eur Heart J. 2019; 40: 476-484https://doi.org/10.1093/eurheartj/ehy641Crossref PubMed Scopus (139) Google Scholar These technologies either target the valve (repair, replacement, annular remodeling) to address the TR or the venae cavae (VC) to prevent the downstream complications of the reflux. For valve therapies, VC are the main access route to deliver the equipment, ideally in a coaxial fashion, to the tricuspid valve (TV). This may be challenging and depends on the angulation, distance, and offset between the VC axes (access) and the TV axis (target). For heterotopic valve therapies, caval valve implantation (CAVI) is used in patients with right heart failure and unsuitable anatomy for orthotopic TV replacement or transcatheter edge-to-edge repair, who are at high or prohibitive surgical risk for TV surgery. However, little is known about the normal VC dimensions and how they change in patients with severe TR, important data for device sizing and anchoring. We included 71 patients with isolated severe TR and none to mild mitral regurgitation (MR), referred to the Cleveland Clinic between 2017 and 2022 who had undergone multiphase cardiac computed tomography (CT) with right-sided contrast. Comparator groups included patients with isolated severe MR and none to mild TR, matched by age and gender (caliper 0.1) and patients without any valvular dysfunction (normal coronary CT), matched by gender (caliper 0.1). We evaluated VC diameter and area at the junction with the right atrium (RA), junction with supra-hepatic veins for inferior VC (IVC) and at the level of the pulmonary artery (PA) for superior VC (SVC). These measurements were done at systole and diastole and were stratified based on TR severity. We measured the angle between VC and the TV annulus, the height between these structures and the offset to the TV as previously described by Harb et al.2Harb S.C. Krishnaswamy A. Kapadia S.R. Miyasaka R.L. The inferior vena cava-tricuspid valve anatomic relationship: an underrecognized cornerstone for transcatheter tricuspid valve interventions.JACC Cardiovasc Imaging. 2023; 16: 118-127https://doi.org/10.1016/j.jcmg.2022.07.023Crossref Scopus (0) Google Scholar All measurements were indexed to body surface area. Variables are presented as mean ± standard deviation. We used analysis of variance (ANOVA) test for comparison between groups. This study was approved by the Institutional Review Board of the Cleveland Clinic. Of 206 included patients, mean age was 77 years for the TR and MR groups and 38 years for the control group with 58%, 64%, and 56% females, respectively. Mean TV effective regurgitant orifice area was 0.66 ± 0.32 cm2 in the TR group, with 30% having torrential TR, and mitral valve effective regurgitant orifice area being 0.42 ± 0.23 cm2 in the MR group. VC dimensions were significantly larger in the severe TR cohort (Table 1), although no significant differences in systole versus diastole were observed (area of IVC at supra-hepatic veins junction mean 3.91 vs 3.87 cm2/m2; p = 0.53, and area of SVC at level of PA mean 2.67 vs 2.43 cm2/m2; p = 0.161). The IVC offset was increased in patients with severe TR compared to the MR and control group (mean 9.79, 7.08, and 5.87 mm/m2, respectively; p < 0.001). On the contrary, while the SVC to TV angle was smaller in patients with severe TR compared to the other groups, the IVC angle was larger.Table 1Cardiac CT angiography VC dimensions between groupsIndexed variables≥ Severe TR (n = 71)Stratified TR severitySevere MR (n = 64)Controls (n = 71)p val†p value for ANOVA test comparing ≥ severe TR vs severe MR vs controls.Severe TRMassive TRTorrential TRp val∗p value for ANOVA test comparing severe vs massive vs torrential TR.Indexed IVC dimensions, mean/BSA (SD) RA junction area at systole, cm2/m24.89 (1.9)4.94 (1.99)4.74 (1.74)5.22 (1.35)0.7033.56 (1.3)2.92 (0.9)< 0.001 RA junction area at diastole, cm2/m24.72 (1.7)4.80 (2.03)4.54 (1.52)5.13 (1.34)0.5213.33 (1.0)2.92 (0.9)< 0.001 RA junction diameter at systole, mm/m215.61 (3.2)18.25 (4.08)17.59 (3.27)19.44 (2.61)0.24715.61 (3.2)13.71 (2.9)< 0.001 RA junction diameter at diastole, mm/m217.82 (3.2)18.16 (3.87)17.27 (3.09)19.09 (2.46)0.20115.06 (2.5)13.77 (2.7)< 0.001 SHV junction area at systole, cm2/m23.91 (1.2)3.97 (1.14)3.53 (1.13)4.74 (1.10)0.0153.03 (0.9)2.81 (0.9)< 0.001 SHV junction area at diastole, cm2/m23.87 (1.2)3.84 (1.30)3.64 (1.18)4.62 (1.09)0.073.05 (0.9)2.91 (0.9)< 0.001 SHV junction diameter at systole, mm/m216.34 (2.8)16.59 (2.47)15.29 (2.84)18.53 (2.46)0.00615.17 (3.6)13.47 (2.9)< 0.001 SHV junction diameter at diastole, mm/m216.24 (2.6)16.47 (2.48)15.51 (2.92)18.05 (2.29)0.03414.55 (2.4)13.7 (2.9)< 0.001 Length from RA junction to SHV junction at systole, mm/m29.44 (6.4)9.19 (9.83)10.04 (6.19)8.35 (6.16)0.7839.06 (3.7)9.12 (4.8)0.934 Length from RA junction to SHV junction at diastole, mm/m29.8 (6.7)10.60 (10.20)10.47 (6.22)6.93 (4.54)0.299.17 (3.5)9.5 (5.0)0.839 Offset, mm/m29.79 (5.6)10.83 (4.59)10.03 (5.99)7.98 (4.67)0.3677.08 (4.4)5.87 (2.9)< 0.001 Angle to TVA, degrees/m251.36 (9.9)6.34 (4.71)4.83 (4.48)8.36 (4.70)0.0748.45 (11.3)46.8 (10.7)0.038 Height to TVA, mm/m227.98 (8.7)53.61 (8.72)50.52 (9.88)51.32 (9.24)0.68321.69 (8.1)16.84 (5.5)<0.001Indexed SVC dimensions, mean/BSA (SD) Level of PA area at systole, cm2/m22.67 (0.9)2.84 (0.98)2.41 (0.80)3.31 (0.90)0.0121.71 (0.7)1.26 (0.5)< 0.001 Level of PA area at diastole, cm2/m22.43 (0.9)2.51 (1.01)2.26 (0.65)2.83 (0.82)0.0851.97 (1.5)1.22 (0.5)< 0.001 Level of PA diameter at systole, mm/m213.46 (2.7)13.94 (2.65)12.63 (2.48)15.41 (2.26)0.00610.58 (2.8)9.03 (2.3)< 0.001 Level of PA diameter at systole, mm/m212.89 (2.7)13.14 (2.64)12.23 (2.14)14.31 (3.09)0.04910.89 (2.5)8.89 (2.0)< 0.001 RA junction area at systole, cm2/m23.72 (1.6)4.16 (1.63)3.36 (1.42)4.48 (1.56)0.0761.66 (0.7)1.23 (0.5)< 0.001 RA junction area at diastole, cm2/m23.34 (1.4)3.75 (1.78)3.13 (1.21)3.62 (1.53)0.3941.85 (1.4)1.11 (0.4)< 0.001 RA junction diameter at systole, mm/m215.84 (3.7)16.84 (3.50)14.79 (3.83)17.88 (3.27)0.03810.68 (2.7)8.92 (2.3)< 0.001 RA junction diameter at diastole, mm/m214.97 (3.5)15.94 (3.98)14.38 (3.48)15.81 (3.61)0.35110.72 (2.6)8.5 (1.9)< 0.001 Length from RA junction to PA level at systole, mm/m214.3 (4.9)13.29 (5.05)15.12 (5.41)12.93 (5.18)0.40714.27 (4.9)13.7 (5.6)0.817 Length from RA junction to PA level at diastole, mm/m214.8 (5.3)14.73 (6.50)15.44 (5.55)12.62 (5.00)0.30313.98 (4.5)13.5 (5.2)0.312 Offset, mm/m25.84 (4.8)6.34 (4.71)4.83 (4.48)8.36 (4.70)0.076.13 (4.8)3.43 (2.6)< 0.001 Angle to TVA, degrees/m258.34 (12.0)53.61 (8.72)50.52 (9.88)51.32 (9.24)0.68363.83 (10.4)59.11 (11.9)0.017 Height to TVA, mm/m228.02 (7.4)59.79 (9.68)55.80 (12.4)60.72 (10.02)0.35520.89 (6.2)15.58 (4.4)< 0.001Bold values indicate p < 0.05.BSA, body surface area; CT, computed tomography; IVC, inferior vena cava; MR, mitral regurgitation; PA, pulmonary artery; RA, right atrium; SD, standard deviation; SHV, supra-hepatic veins; SVC, superior vena cava; TR, tricuspid regurgitation; TVA, tricuspid valve annulus.∗ p value for ANOVA test comparing severe vs massive vs torrential TR.† p value for ANOVA test comparing ≥ severe TR vs severe MR vs controls. Open table in a new tab Bold values indicate p < 0.05. BSA, body surface area; CT, computed tomography; IVC, inferior vena cava; MR, mitral regurgitation; PA, pulmonary artery; RA, right atrium; SD, standard deviation; SHV, supra-hepatic veins; SVC, superior vena cava; TR, tricuspid regurgitation; TVA, tricuspid valve annulus. Understanding the VC anatomy, their dimensions (at various levels), and spatial relationship (angle, offset, distance) to the TV are crucial for TTVI procedural success, although these considerations remain not well studied, underappreciated, and often overlooked. To our knowledge, this is the first detailed report assessing the VC anatomic characteristics as they pertain to TTVI on cardiac CT, which is typically used for procedural planning.3Layoun H. Schoenhagen P. Wang T.K.M. et al.Roles of cardiac computed tomography in guiding transcatheter tricuspid valve interventions.Curr Cardiol Rep. 2021; 23: 114https://doi.org/10.1007/s11886-021-01547-7Crossref Scopus (2) Google Scholar Procedural evaluation for CAVI also requires the presence of significant caval reflux for proper valve function after implantation. Earlier heterotopic therapies mainly involved the IVC with complications including residual leaks, improper sizing, and device embolization and thrombosis.4Abdul-Jawad Altisent O. Benetis R. Rumbinaite E. et al.Caval valve implantation (CAVI): an emerging therapy for treating severe tricuspid regurgitation.J Clin Med. 2021; 10: 4601https://doi.org/10.3390/jcm10194601Crossref Scopus (8) Google Scholar Currently, TricValve (Products + Features) is the only dedicated CAVI system. The early experience of TricValve in 35 patients has demonstrated the procedure’s feasibility (94% procedural success) and safety (no procedural deaths or conversions to surgery) as well as functional status and patient-reported quality of life (NYHA functional class and Kansas City Cardiomyopathy Questionnaire) benefits.5Estévez-Loureiro R. Sánchez-Recalde A. Amat-Santos I.J. et al.6-Month outcomes of the TricValve system in patients with tricuspid regurgitation: the TRICUS EURO study.JACC Cardiovasc Interv. 2022; 15: 1366-1377https://doi.org/10.1016/j.jcin.2022.05.022Crossref PubMed Scopus (17) Google Scholar However, these findings are largely limited by the small sample size. With the increasing use of CAVI therapies, knowing how substantially larger the VC dimensions are in the severe TR group has important implications, particularly in terms of device sizing and catheter approach in advanced disease. First, we present the VC dimensions at multiple levels for patients with severe TR and how they compare to normal younger patients (normal coronary CT) and age-matched and gender-matched patients with nonsevere TR (MR group). Second, since these dimensions were not significantly different across the cardiac cycle, a single-phase CT rather than a multiphasic acquisition may be used, significantly limiting the amount of radiation exposure associated with such scans. Finally, the angulation, distance, and offset required to reach the TV in a coaxial fashion from both the SVC and IVC are outlined, which have important implications in terms of designing TTVI delivery guides’ physical properties and capabilities in terms of maneuverability. Careful understanding of the VC anatomic characteristics is key for TTVI procedural success, as they are either the access routes or the targets for these rapidly evolving therapies. This study was approved by the Institutional Review Board of the Cleveland Clinic, and written informed consent was waived. This work was supported by unrestricted philanthropic support to the Cleveland Clinic Heart, Vascular, and Thoracic Institute. The funding source had no role in the design or conduct of the study; the collection, management, analyses, or interpretation of the data; the preparation, review, or approval of the manuscript; or the decision to submit the manuscript for publication.