**3. Historical insight on allograft valve substitutes for tricuspid valve surgery**

The first mitral homograft in humans was performed in 1965 by Senning. Since that time, there has been a limited number of implants mainly because of technical difficulties related to the insertion of the papillary muscles. Homologous transplantation of the mitral valve was also applied for TVR in the case of infective endocarditis or for the replacement of a degenerated bioprosthesis. Satisfactory results have been reported. However, due to the lack of anatomical landmarks, the implantation procedure has remained technically challenging. Thus until further progress demonstrated a clear superiority of the mitral homograft, bioprosthesis has remained the gold standard for replacing the mitral or the tricuspid valve with a biological substitute [25].

The most significant surgical experience with allografts in tricuspid surgery was reported by Hvass U., et al., 2002–9 patients, Couetil J.-P.A., 2002–7 patients, Kalangos A., 2004–8 patients [26–28].

The largest world experience with tricuspid homografts in the tricuspid position was depicted by Shrestha B.M.S. in 2010 and included 14 patients [9].

It should be mentioned that the overall allografts data regarding both mitral and tricuspid valve surgery is confined to small case series with a lack of initial and longterm results. Surgical techniques have not been described properly as well.

#### **3.1 Indication for surgery and types of allografts used in tricuspid position**

According to world surgical experience of allografts for tricuspid valve disease, the most relevant indications for interventions were: infective endocarditis, rheumatic heart disease, degenerative and congenital heart diseases including Ebshtein anomaly, bioprosthetic dysfunction (**Table 1**) [9, 29, 30]. Allografts had been utilized both in primary and redo cases [9, 29].

#### **3.2 Surgical techniques**

Historically, mitral and tricuspid homografts in the tricuspid position were used either for total (complete) valve replacement or for partial TVR, usually anterior tricuspid leaflet. Positioning of the mitral homograft in the tricuspid annulus also varied throughout the studies. Anti-anatomical orientation of the mitral homograft (anterior homograft leaflet to the septal portion of tricuspid annulus) was first introduced by J.L.Pomar, C.A.Mesters and many other authors followed such technique (**Table 2**) [30]. Conversely, anatomical orientation (anterior homograft leaflet to anterior portion of tricuspid annulus) was proposed only by Couetil J.-P.A., 2002 and Kalangos A., 2004 [27, 28].

The most challenging issue has always been securing homograft's papillary muscles in the right ventricle cavity. Right ventricle papillary muscles, along with the free wall and interventricular septum had been proposed for papillary muscle fixation (**Table 2**). Annuloplasty as a bail-out procedure was described in some studies, by the way, the data is inconclusive.

#### **3.3 Outcomes**

Initial and long-term results of allografts in tricuspid surgery are summarized in **Table 3**. Early and 30-day mortality was not reported in any study. Postoperative complications included a complete atrioventricular block in one study from Ostrovsky Y., 2015 and – postoperative bleeding that required resternotomy in another study from Luciani G.B., 2021 [32, 33]. Overall survival at the end of the follow-up period was 100 [90,7–100] %, freedom from graft dysfunction — 100%, and freedom from reoperation — 100 [79–100] %. All authors confirmed complete recovery from infection in patients who had undergone surgery due to infective endocarditis.


#### **Table 1.**

*Indication for surgery and allograft type for tricuspid valve (world data).*

*Contemporary Approach with Mitral Valve Allograft in the Treatment of Tricuspid Valve… DOI: http://dx.doi.org/10.5772/intechopen.111687*


**Table 2.**

*Surgical aspects for homograft tricuspid valve replacement (world experience).*
