**3. Discussion**

Cardiac valve allografts have been thought to be plausible valve substitutes in wide spectrum of surgical scenarios. In addition, it is also believed that allograft's availability enables to broad technical opportunities [5, 6]. Regarding radical treatment of hepatocellular carcinoma with tumor thrombi in the inferior vena cava or right atrium, surgical removal of thrombotic masses from the inferior vena cava and the right atrium remains to the most efficient method of treatment that can reduce the risk of systemic metastasis and sudden death due to pulmonary thromboembolism or occlusion of the tricuspid valve by a tumor thrombus [7]. Without surgical repair, the median survival is less than 12 months, and chemotherapy has not demonstrated acceptable survival [8, 9]. Descriptive and comparative analysis of different types of allograft tissue in inferior vena cava replacement has not been provided in available databases. Arterial and venous allografts could also be considered feasible prosthetic material, although pulmonary homograft conduit was optimal for two main reasons. Firstly, pulmonary allograft was available for subsequent use. Secondly, a bigger size

#### **Figure 10.**

 *Postoperative TTE. Apical 4-chamber view. Excellent leaflet coaptation without residual regurgitation on mitral homograft in tricuspid position.* 

of pulmonary conduit seemed to be more advantageous for dilated patient's inferior vena cava and more suitable for right atrium reconstruction. Nevertheless, diverse spectrum of allograft tissue conduits should be carefully investigated in such procedures. Our experience suggests in favor of radical surgical treatment where allograft tissue demonstrated its relevant implication with excellent results.

 Another challenging circumstance is destructive double valve infective endocarditis with central fibrous body involvement. There are no systematic results of aortomitral homograft implantation for such patients, and these operations are rarely performed [ 10 , 11 ]. Theoretically, the main advantages of the method are the absence of synthetic material and no need for anticoagulation. Another potential benefit of the aortomitral homograft is the preservation of mobility of the supporting apparatus, which may be important for long-term homograft function and cardiac performance. Mechanical valves remain the most commonly used substitute for double valve replacement, still carrying the high risk of bleeding and thromboembolic events in the long run. Potential benefits of allografts in favor of re-infection resistance have not been proved in randomized trials; by the way, such trials are limited. Current clinical guidelines are inconclusive regarding valve choice in different clinical scenarios, which formally enables the heart team to create their own strategy based on the patient's clinical status, urgency, and graft availability. From our point of expertise, allograft double valve replacement might well be taken into account, given full respect to obvious benefits and potential drawbacks in the mid- and long-term.

 Concomitant cardiac procedures with cardiac valve allografts are rare and have not been described precisely. Cardiac involvement in Bekhterev's disease usually

#### *Clinical Implication of Cardiac Valve Allografts in Rare Surgical Circumstances DOI: http://dx.doi.org/10.5772/intechopen.112865*

manifests as aortic insufficiency, aortitis, or cardiac conduction abnormalities. Mitral insufficiency is less commonly defined, predominantly when subaortic fibrosis reaches the anterior mitral valve leaflet [12, 13]. Experience with mitral homograft implantation has shown that valve lesions of rheumatic etiology, which include Bekhterev's disease, may be a major indication for this technique [14]. When it comes to the method of aortic valve repair, there was a choice between a biological valve, the Ross procedure, and neocuspidization, because the patient avoided anticoagulation. Low durability of the Ross procedure in rheumatic disorders may be due to autoimmune response to type IV collagen, which is contained in the valve leaflets [15]. The experience with biological valves in rheumatic diseases is similarly unsatisfactory, with early degeneration and an increased risk of reoperation [16]. We reckon that allografts and reconstructive surgery using autologous materials provide a better hemodynamic profile along with avoidance of lifelong anticoagulation therapy. Autopericardial neocuspidization could be under the scope of surgical interest, regarding their potential "bridging" role in reconstructive surgery, avoiding anticoagulation-related complications and enabling more radical surgery (allograft root replacement) or transcatheter aortic valve replacement in long-term.

Considering MAs application in reconstructive tricuspid surgery, there is a sustained interest in terms of superior initial results, high hemodynamic performance, and potentially lower risk of complication in long-term follow-up [1, 17, 18]. A recent meta-analysis shows neither biological nor mechanical prosthesis provide satisfactory early and long-term results [19, 20]. MA could probably outweigh biological prosthesis in hemodynamic performance and long-term outcomes, but the data is confined to few clinical studies but with promising initial results, which encourage wider acceptance of MA in tricuspid position. Moreover, in cases where tricuspid repair cannot be performed, current guidelines and markets give no particular feedback regarding prosthetic choice, and stented biological valves along with mechanical are still recommended. Our study gives practical insight into feasibility of MA in the treatment of degenerative TV pathology in patients who does not accept traditional prosthetic options. Concomitant cryoablation for atrial fibrillation in combination with homograft implantation has not been described in available databases.

### **4. Conclusion**

Assuming our surgical experience with cardiac valve allografts in unusual clinical cases, we can conclude that allograft valves might take place as a plausible prosthetic tissue in a wide spectrum of diseases. Marked hemodynamic performance and excellent early and mid-term results could be achieved with low risk of complications and zero mortality in selected patients. Technical procedure-related challenges could be confidently resolved by having pliable allograft material available at the time of operation. Patient's desires and preferences still play a crucial role in decision-making. Further investigations are needed to prove potential benefits of allografts in cardiovascular surgery.
