**4. Contemporary approach for mitral allograft as a feasible prosthetic substitute in tricuspid valve surgery. Two-center experience**

#### **4.1 Patients and methods**

#### *4.1.1 Patient's population*

Between October 2021 and February 2023, a total of 20 patients underwent TVR by means of mitral homograft at the two institutions ("Chelyabinsk Regional Clinical Hospital" and the "Sechenov University"). This study was approved by the Regional Ethics Committee of the 2 hospitals, and all patients signed their informed consent. The Institutional Review Board approved this study (# 19\_2021) on 18 October 2021. The baseline clinical characteristic is depicted in **Table 4**.

#### *4.1.2 Preoperative assessment and indication for surgery*

Preoperative assessment included calculating EuroScore II risk, Tri-Score band, and MELD Score regarding the patient's age, clinical symptoms of right heart failure, ejection fraction, daily Furosemide intake, and major laboratory findings. Estimated and predicted in-hospital mortality and morbidity along with 3-month predicted mortality were taken into consideration [34–36].


#### **Table 3.**

*Early and long-term outcomes for homograft tricuspid valve replacement (world experience).*

### *4.1.3 Surgical intervention*

TVR was performed using conventional cardiopulmonary bypass with bicaval cannulation and either cold blood or crystalloid cardioplegia infusion under the full-sternotomy.

### **4.2 Surgical technique for tricuspid valve replacement by means of mitral homograft**

Homograft delivery was carried out by means of express airlines as soon as the decision to use homograft as a valve substitute had been made. All homografts were ordered from Saint-Petersburg Homograft Bank. Homografts implanted in patients were produced according to the specifications TU 9398-001-80,966,705. The starting material for the manufacture of homografts is the tissue components of the cardiovascular system of a deceased person. Unlike other similar methods of preservation, a sparing technique of osmolar decellularization and preservation of the native structure of the connective tissue matrix has been used. The manufacturing technology of this medical product ensures maximum preservation of the native properties of the connective tissue matrix and high hemocompatibility.

Important features of these products are their elasticity and plasticity, which makes it easy to model products during their implantation, taking into account the *Contemporary Approach with Mitral Valve Allograft in the Treatment of Tricuspid Valve… DOI: http://dx.doi.org/10.5772/intechopen.111687*


*M ± SD – mean and standard deviation; Me [Q1-Q3] – median and interquartile range. NYHA – New York Heart Association; HIV – human immune virus; ARVT – anti-retrovirus therapy.*

#### **Table 4.**

*Patient characteristics.*

characteristics of the patient's individual anatomy. Homografts are stored at a temperature of 0 to 4 degrees Celsius or be cryopreserved and stored at a temperature of minus 150 degrees Celsius.

A homograft for mitral valve replacement is represented by a mitral valve with a muscular layer in the area of the annulus fibrosus, a 5 mm rim of the left atrial endocardium, a chordal apparatus of the mitral valve, and a section of papillary (papillary) muscles with a sutured platform.

**Figure 1.** *Mitral homograft with papillary muscles reinforced with pericardial flap.*

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

In the manufacture of a medical product, the distance of the marginal chords to the papillary area is estimated and taken into account during its formation.

Freshly prepared products are stored in solution for 3 months. During this period should be implanted.

The sterility of each product is confirmed by negative microbiological and virological tests. It should be mentioned that the base of each homograft papillary muscle is reinforced with a pericardial flap for reliable suturing (**Figure 1**).

Assuming there is no guideline for sizing homografts preoperatively, our choice was based on measured tricuspid annulus diameter and surgical experience. The patient's body size, right ventricle dimensions, and pulmonary artery pressure were taken into account as well.

The original technique for TVR with mitral homograft that was proposed and utilized in our clinical had been described previously [37]. Further steps were partially modified in order to simplify the procedure and make results more predictable and stable. Those were: 1. keeping mitral homograft posterior leaflet totally oriented to septal portion of tricuspid annulus and anterior mitral homograft leaflet oriented straight opposite to the septal part, which is believed to preserve natural orientation of all homograft structures as a functional unit; 2. Harvesting and taking away any residual muscular tissue of homograft annulus; 3. Systematic use of rigid ring, either synthetic or biological (bovine pericardium); 4. Correction of any residual leaflet prolapse by suturing polytetrafluoroethylene (PTFE) chords. We did not take into account the complex anatomy of papillary muscle and diverse papillary head distribution, whereas the number of main muscles (generally 2), and their size was given full respect. Homograft papillary muscles were pre-implanted first in order to reduce the risk of tear of interventricular myocardium when the annulus was in place. The proper point for papillaries was chosen in accordance with measurements made on homograft (**Figures 2** and **3**).

In all cases, homograft papillary muscles were reimplanted to the interventricular septum just above the reflection of the supraventricular crest of the RV (for anterolateral homograft papillary muscle) and left to the anterior papillary muscle of the RV (for posteromedial homograft muscle) (**Figure 3**). Interpapillary distance was measured in all cases as well in order not to distort homograft anatomy (**Figure 4**). For papillary muscle, fixation were routinely used PTFE chords. Not only did it provide firm fixation, but also allowed further leaflet repair in case of residual prolapse (**Figure 5**).

Based on these principles, mitral homograft was oriented as a functional unit in the inlet part of the right ventricle cavity, given full respect to mitral valve apparatus and RV hemodynamic. Never have we ever considered the RV-free wall for papillary muscle fixation.

#### *4.2.1 Echocardiographic assessment*

Transthoracic ECHO was routinely performed by experienced medical technologists, before surgery, at 1 week, 6 months, and 1 year postoperatively. Preoperative and postoperative assessments, including grading of valve regurgitation, ventricles volumes, and function, were obtained according to guidelines [38]. All patients underwent intrapreoperative TOE ECHO to determine the degree of severity and location of tricuspid regurgitation and the final repair result.
