**7. Outcomes**

### **7.1 Valved conduits**

Dacron conduits create thick intimal peel that requires explantation at the time of repeat operations. Homografts and bovine jugular veins show variable degrees of durability, but early degeneration and calcifications are sometimes inevitable (**Figure 10**). Added to this is their limited availability in many countries.

### **Figure 10.**

*Preoperative CT scan showing calcified bovine jugular vein graft in patient who underwent repeat sternotomy for pulmonary conduit replacement.*

A multicenter study in Japan included 794 patients (aged 14 days to 56.8 years old) in which e-PTFE valves were used for RVOT reconstruction at 52 Japanese institutes had a mean follow-up of 3.6 years (maximum 10 years) [16]. The e-PTFE was in the form of fan-shaped valved conduits and patches with bulging sinuses. The freedom from reoperation at 10 years was 95.4% in patients with conduits and 92.3% in those with patches. No or mild pulmonary regurgitation was present in 95 and 79.6% of those with conduits and those with patches, respectively.

### **7.2 Biological prostheses**

In general, there are conflicting reports in the literature regarding the durability of various prostheses in the pulmonary position. Bando et al. observed that 94% of homografts have good function after 5 years; however, almost 25% had evidence of moderate-to-severe calcifications (**Figure 11A** and **B**) [17].

Regarding bioprosthetic conduits, a failure rate of 15% of 3 years was observed in the study by Cleveland et al. and calculated that 55% would have avoided a reoperation at 5 years [18].

In the study by Batlivala et al., the authors compared bioprostheses and homograft conduits in the pulmonary position [19]. This included 254 patients aged 10–21 years old. The median follow-up was 4.4 years. Freedom from valvar dysfunction was 72% ± 4% at 5 years and 48% ± 8% at 10 years. Freedom from RVOT re-interventions was 90% ± 3%, and 67% ± 5% at 5 and 10 years, respectively. No differences were present between bioprosthesis and homografts.

### **7.3 Mechanical prostheses**

In a study from Mayo Clinic, 59 patients underwent mechanical PVR between 1965 and 2013, and no valve thrombosis was observed in the settings of adequate anticoagulation with Warfarin. The maximum follow-up in this study extended to 20 years with no reoperations related to pannus formation, paravalvular leak, endocarditis, valve thrombosis, or prosthetic dysfunction.

The range of reported thrombosis for a mechanical PVR varies from 25 to 80% [20]. These thrombotic complications were reported with bileaflet mechanical prostheses, and none was reported in those with a tilting-disk prosthesis, although literature on this topic is spared in general. The reported complication rate of a bileaflet

### **Figure 11.**

*Preoperative images of a patient who had previous aortic homograft placed in the right ventricular outflow tract for repair of tetralogy of Fallot with pulmonary atresia. (A) Chest X ray showing extensive and complete calcifications of the homograft pulmonary conduit (white circle), (B) which is confirmed by preoperative cardiac catheterization (multiple white arrows). Notice the close proximity of the pulmonary conduit to the back of the sternum.*

prosthesis in the pulmonary position has been about 35%. The majority of these thrombotic events were observed in those who were not adequately anticoagulated with Warfarin. Taken together, the frequency of thrombosis if the patient was not maintained on Warfarin was 41% (15 of 37 prostheses failed); however, if the patient is adequately anticoagulated, the rate of thrombosis dropped to 3.5% [21, 22]. These observations are seen also in the series reported by Freling et al., which spanned 26 years and included 66 patients [23]. Actuarial freedom from reoperation was 96% at 5 years and 89% at 10 years.

A meta-analysis of 299 patients from 19 observational studies by Dunne et al. documented nonstructural deterioration and valve thrombosis rates of 1.5 and 2.2%, respectively [24]. Redo surgery was needed in 0.9%, and thrombolysis was used in 0.5%. This is the largest analysis to date and confirms the low incidence of valve dysfunction and thrombosis for mechanical prostheses in the pulmonary position.

### **8. Conclusions**

The pulmonary valve can be affected by a variety of congenital and acquired diseases. Although repair or preservation of the pulmonary valve may be possible in certain cases, replacement is usually required whether in primary or reoperative settings based on the original, pathology affecting the pulmonary valve/RVOT.

Surgical approaches can be through (repeat) sternotomy, left posterolateral thoracotomy, or minimally invasive left anterior minithoracotomy.

Several options are available for the replacement of the pulmonary valve with or without reconstruction of the RVOT. The most commonly used options include homografts and bioprosthetic or mechanical valves. While our first choice as a prosthesis for PVR is a biological valve that facilitates subsequent transcatheter interventions (**Figure 12**), the deciding factor between any of these options depends on the patient's clinical profile especially age, original pathology/indication, prosthesis availability, and future expectations for this patient and therefore, it should be individualized. Other novel strategies such as handmade e-PTFE conduits and autologous pericardial leaflet reconstruction may be considered.

**Figure 12.** *Melody transcatheter valve is they most commonly used transcatheter option after failed pulmonary bioprostheses and homografts.*

Although some of these conduits have long-term data in terms of durability and freedom from reintervention, literatures are limited regarding other techniques and the bottom line is we do not have the ideal pulmonary valve/conduit yet.
