“ I think if there were a [ transcatheter ] therapy people would look for this disease and be more aggressive about it ,” said Dr . Webb in a July 2016 ACCEL interview . “ Right now there ’ s not much to do for a lot of these people so we often ignore TR unless the patient has frank severe edema or ascites or both .”
Which is too bad because moderate-to-severe TR adversely impacts functional status in patients with left heart disease and is an independent risk factor for poor survival . 5 And tricuspid surgery in high-risk patients can have an operative mortality rate as high as 22 %, so surgery is often not even attempted . 7
Tricuspid annuloplasty remains the go-to technique for functional TR in patients undergoing left-sided valve surgery in an attempt to prevent evolution to severe TR and eventual right ventricular ( RV ) dysfunction . However , there are currently no specific interventional concepts for tricuspid valve disease other than balloon valvuloplasty for tricuspid stenosis . 5
Recently , Rodes-Cabau and colleagues reviewed the novel transcatheter treatment options for treating patients with severe TR and right heart failure with prohibitive surgical risk . 8 They described the devices for implantation aimed at different levels : the junction between vena cavae and right atrium ; the tricuspid annulus ; or between TV leaflets , improving coaptation . Outcomes were collated for five different transcatheter TR therapies : Tric valve , Sapien valve , Forma , Trialign ( from the same folks who brought us the Mitralign system ), and TriCinch ( 4Tech Cardio Ltd .) None of the patient samples exceeded 10 , meaning all we can say is the findings are early but promising .
Another , albeit inelegant , approach has been to use transcatheter valves off-label to treat dysfunctional bioprostheses . To date , the literature on tricuspid valve-invalve implantation ( TVIV ) or in a previously repaired valve has been limited to small case series or case reports . TVIV replacement is an appealing option for many patients insofar as it may avoid higher-risk redo sternotomy and TV surgical replacement in patients who are often clinically compromised
Despite this growing practice , this way off-label transcatheter approach is not being studied prospectively . Recently , worldwide data were gathered and reported . 9 Data were collected on 156 patients with bioprosthetic TV dysfunction who underwent catheterization with planned TVIV . Median age was 40 and 71 % of patients were in New York Heart Association ( NYHA ) class III or IV . TVIV was attempted in 152 patients using either a Melody transcatheter pulmonary valve ( n = 94 ) or a Sapien transcatheter aortic valve ( n = 58 ). ( Remember , we ’ re in the tricuspid valve here !)
After TVIV , both the TV inflow gradient and TR grade improved significantly . The vast majority of procedures were technically successful and resulted in improved TV function , regardless of surgical or transcatheter valve type or size , patient age , or underlying cardiovascular condition . Although there was substantial mortality during median 13.3-month follow-up — 22 patients died — there were few early or valve-related deaths , and mortality was concentrated in patients who were in poor condition before TVIV .
At follow-up , 77 % of patients were in NYHA class I or II ( meaning a complete reversal from baseline , with a p < 0.001 versus before TVIV ). Outcomes did not differ according to surgical valve size or TVIV valve type . Given the hemodynamic and clinical improvement and the low incidence of adverse events , the authors concluded that the risk-benefit profile of TVIV is generally favorable , especially considering that most of the hospitalized patients were able to be discharged after TVIV and , in this very sick cohort , most of the survivors reported substantial symptomatic improvement .
As well , there are a few valve devices designed for heterotopic superior vena cava ( SVC ) and inferior vena cava ( IVC ) deployment . Heterotopic approaches , of course , do not directly address the TR but do address the regurgitation of blood into the caval veins , which is often seen in patients with severe , long-standing TR and RV enlargement . Caval valve implantation ( CAVI ) has demonstrated encouraging results in preclinical study and the technique is relatively quick and easy to perform .
The self-expanding Tric Valve ( P & F Products & Features ) is specifically designed for this purpose , but balloon-expandable valves normally used in the aortic positions have also been tested for CAVI , including the 29 mm Edwards Sapien XT or Sapien 3 , which is under evaluation for this indication in a few open-label studies . The Tric Valve uses a 27-F flexible catheter for transvenous implantation and comes sized as large as 43 mm for the IVC and up to 38 mm for the SVC .
“ If you implant two of these in the SVC and IVC , you sort of replicate the function of the tricuspid valve except you still have regurgitation into the atrium , but at least not into the SVC or IVC ,” explained Dr . Webb . “ Most implants have just been in the IVC alone with the hopes that this would reduce abdominal bloating , reduce ascites , pedal edema , hepatic congestion , and that ’ s where most of the symptoms come from .”
Transcatheter tricuspid valve replacement is so far just a dream . To date , it appears there have not been any attempts at a full transcatheter tricuspid valve replacement in humans . 8 “ The problem is the tricuspid valve is very asymmetric ,” said Dr . Webb . “ It doesn ’ t have a fibrotic or calcific structure so it ’ s difficult to transplant a valve in the tricuspid position percutaneously ; secure fixation just isn ’ t going to happen .”
“ Nonetheless ,” Figulla et al . wrote , “ it is probably correct to predict that the percutaneous approach will be the treatment of choice in patients requiring a reintervention on the tricuspid valve after previous tricuspid surgery .” 5
Pulmonic Valve : The Wallflower Pulmonary valve stenosis is related to a congenital or genetic disorder in the vast majority of cases , but 80 % occur in isolation . 10 Most with mild-tomoderate stenosis — and even some with severe stenosis — are asymptomatic . Generally , pulmonary balloon valvotomy is indicated if the instantaneous transpulmonary gradient exceeds 50 mm Hg . But in patients with degenerated RV outflow conduits
( RVOT ) and biological valve restenosis , balloon dilation alone is associated with frequent restenosis .
Transcatheter pulmonic valve replacement can be performed for patients with stenotic biological valves or grafts , RVOT dysfunction , or in those with significant pulmonary regurgitation . Available devices include the Melody transcatheter pulmonary valve ( TPV ; Medtronic ) and the Sapien XT valve , both of which are approved for pulmonic use .
The Melody valve has a size limitation ( maximum outer diameter of 24 mm ), but a good amount of data showing its efficacy and safety . The Sapien valve has a diameter of 29 mm , which allows for treatment of larger diameter RVOTs , but there are few long-term data on the Sapien valve in the pulmonary position .
Aortic root compression can occur during balloon angioplasty of the RVOT prior to pulmonary valve interventions but it appears it can be avoided using precautions and , in most cases , is transient
11 , 12 and benign .
Valve Futures It seems pretty likely that more and more valve interventions will be performed percutaneously in the near and , let ’ s say , less-near future . What ’ s next ? “ We are at the beginning of understanding the genetic background of [ aortic stenosis ] but the understanding of environmental factors contributing to valvular heart disease is beyond the scope of our present understanding ,” wrote Figulla and colleagues in their comprehensive review of transcatheter valve therapies . 5 Could prevention be the final frontier , grad school so to speak ? They concluded their review with a call for more basic science research looking at the causes of valvular heart disease , going far beyond poorly treated strep infections to gaining a better understanding of the “ pathophysiology of valvular tissue destruction .” ■
REFERENCES : 1 . Nkomo VT , Gardin JM , Skelton TN , et al . Lancet .
2006 ; 368:1005-11 .
2 . Mozaffarian D , Benjamin EJ , Go AS , et al . Circulation . 2016 ; 133 : e38-e360 .
3 . Reynolds MR , et al . J Am Coll Cardiol . 2016 ; 67:29-38 .
4 . Leon MB , Smith CR , Mack MJ , et al . New Engl J Med . 2016 ; 374:1609-20 .
5 . Figulla HR . Eur Heart J . 2016 May 8 [ Epub ahead of print ].
6 . Testa L , Latib A , Montone RA , et al . J Thorac Cardiovasc Surg . 2016 Apr 29 [ Epub ahead of print ].
7 . Filsoufi F , Anyanwu AC , Salzberg SP , et al . Ann Thorac Surg . 2005 ; 80:845-50 .
8 . Rodes-Cabau J , Hahn RT , Latib A , et al . J Am Coll Cardiol . 2016 ; 67:1829-45 .
9 . McElhinney DB , Cabalka AK , Aboulhosn JA , et al . Circulation . 2016 ; 133:1582-93 .
10 . Lin G , Bruce CJ , Connolly HM . Diseases of the tricuspid and pulmonic valve . In : Otto CM , Bonow RO , editors . Valvular Heart Disease , A Companion to Braunwald ’ s Heart Disease . 4 th ed . Philadelphia , PA : Elsevier , 2014 .
11 . Torres EJ , McElhinney DB , Anderson BR , et al . J Interv Cardiol . 2016 ; 29:197-207 .
12 . Lindsay I , Aboulhosn J , Salem M , Levi D . Catheter Cardiovasc Interv . 2016 Apr 28 [ Epub ahead of print ].
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