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\begin{document}

\title{Hand Sewn Bovine Pericardial Conduit with Tri-leaflet Valve in Right
Ventricular Outflow Tract: Review of 41 patients.}



\author[1]{Fitoon Korea}%
\author[2]{Atul Prabhu}%
\author[1]{Rajat Dubey}%
\author[1]{Ms. Shilpi Singh}%
\author[3]{ashish katewa}%
\affil[1]{Sri Sathya Sai Sanjeevani Centre For Child Heart Care}%
\affil[2]{Sri Sathya Sai Sanjeevani hospital}%
\affil[3]{Sri Sathya Sai Sanjeevani Hospital}%


\vspace{-1em}



  
  \date{May 08, 2024}


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\selectlanguage{english}
\begin{abstract}
Introduction: The currently available options for restoring right
ventricle (RV) to pulmonary artery (PA) continuity are far from
satisfactory. In absence of an ideal conduit, hand sewn bovine
pericardial conduit with Polytetrafluroethylene (PTFE) tri-leaflet valve
(BPCTV) may serve as a satisfactory alternative particularly in low and
middle income countries (LMIC). Material and Methods: The hospital
records of all patients who received BPCTV in RV to PA position from
January 2014 to June 2019 were retrospectively analysed. A total of 41
patients were further classified into two groups; pulmonary hypertension
group (PH) and non-pulmonary hypertension group (NPH). The primary
endpoints of the study were mortality, and freedom from re-operation for
conduit failure. The secondary end point was to study the impact of
pulmonary hypertension on the conduit function and durability. Results:
The Mean age and weight of patients at time of conduit implantation was
56.8 months (range 2-196 months) and 12.3 kg (range 3-44 kg)
respectively. The mean size of conduit was 18 mm (range 12-24 mm). The
mean duration of follow up was 30 months (range 8-72 months). The
freedom from re-intervention was 86\% at 30 months (range 8-72 months).
The cost of BPCTV was less than one-sixth of the commercially available
bovine jugular vein conduit. Conclusion: The hand sewn BPCTV is a cost
effective alternative to commercially available conduits with acceptable
outcomes. However, more research with a larger sample size and a longer
follow-up is required.%
\end{abstract}%



\sloppy


\textbf{Introduction}

Restoration of right ventricle (RV) to pulmonary artery (PA) continuity
is an essential component of surgical procedures performed for many
congenital heart defects. In addition to the primary procedure, the
patient will undergo multiple re-operations for revision of the RV to PA
conduit. The cumulative cost of therapy may become substantial in the
first decade of patient's life and is comparable to that of patients
with single ventricle physiology. (1,2) The considerable resource
utilisation for this group of patients can be prohibitive in low and
middle income countries (LMICs).

An ideal RV to PA conduit should be easily available, durable, offer
resistance to infection, prevent thrombosis and able to grow with the
child. Although an ideal conduit does not exist, several options are
available. As stated previously, commercially available conduits are
expensive and can exponentially increase the cost of surgery in low and
middle income countries. Homograft valve banks are resource intensive to
maintain and as a result most paediatric cardiac programs in LMICs do
not have access to homografts. These factors have renewed the interest
in hand sewn conduits. Recent evidence has shown that the hand sewn
conduits implanted in RV to PA position have an acceptable clinical
outcome which compares favourably with the commercially available
conduits. (3) We present a single centre experience with forty one
patients who underwent for RV-PA conduit implantation using bovine
pericardial conduit with tri-leaflet valve (BPCTV).

\textbf{Material and Methods}

The single centre retrospective study included all 41 patients who
received a BPCTV in the RV to PA position between January 2014 to June
2019. Medical records were analysed for the demographic data, surgical
procedure, cardiopulmonary bypass parameters, ventilation duration,
ionotrope score, hospital stay and follow-up evaluation. These patients
were separated into two groups depending on the presence (PH group) or
absence (NPH group) of pulmonary hypertension. (Tabel 1\& 2) The primary
endpoints were mortality and freedom from re-intervention for conduit
failure. The criteria for conduit failure were defined as more than
moderate regurgitation and/or peak gradient of more than 60 mmHg.

\textbf{Surgical Technique}

The conduit was constructed prior to skin incision with a bovine
pericardial sheet (St. Jude Medical, St.Paul, MN) for the tube and 0.1mm
thick e-PTFE (Gore-Tex; W. L. Gore \& Assoc., Newark, DE) for the
tri-leaflet valve. The size of BPCTV conduit was +2 Z score of the
pulmonary valve for the body surface area. Three contiguous cusps are
fashioned from a sheet of 0.1mm e-PTFE membrane and sutured to the
smooth side of bovine pericardial sheet. The bovine pericardial sheet is
rolled over a required sizer and its free edges are sutured to create a
valved conduit. (Figure 1,2) The formula used for constructing conduits
of size 12 to 24 is given in table 3. The surgery was performed through
median sternotomy on Cardiopulmonary bypass with moderate hypothermia.
The choice of Cardioplegia was antegrade delivery of DelNido's solution
at 4 degree C. The distal end of the conduit was sutured to the
pulmonary artery confluence on beating heart in presence of pulmonary
atresia and type 1 Truncus arteriosus. In all other cases, both ends of
the conduit were sutured under cardioplegic arrest.

\textbf{Statistical Methods:}

Descriptive and inferential statistical analysis has been carried out in
the present study. Results on continuous measurements are presented on
Mean \selectlanguage{ngerman}± SD (Min-Max) and results on categorical measurements are
presented in Number (\%). Significance is assessed at 5 \% level of
significance. Student t-test (two tailed, independent) was used to find
the significance between groups (Inter group analysis) on metric
parameters.

\textbf{Results}

The Mean age, weight and conduit size were 56.8 months (range 2-196
months), 12.3 kg (range 3-44 Kg) and 18.4 mm (range 12-24 mm)
respectively. The male to female ratio was 25:16. The age and weight of
children in PH group was significantly lower than those in NPH group.
There were two early death. A child with truncus arteriosus in PH group
died due to intractable pulmonary hypertensive crisis. Another child
with Tetralogy of Fallot and anomalous coronary artery crossing the RVOT
in NPH group died due to right ventricular dysfunction and sepsis. The
conduit was functioning well in all discharged patients. Five patients
(12.2\%) had mild regurgitation, eight patients (19.5\%) had trivial
regurgitation and 28 patients (68\%) had no regurgitation at discharge.

There was one late unrelated death due to pneumonitis and three patients
were lost to follow-up. The remaining thirty-five patients were
evaluated at a mean follow-up duration of 30 months (range 8-72 months).
Four of these patients were followed up telephonically. They were said
to be asymptomatic, but could not be evaluated in the hospital due to
socio-economic constraints. Of the thirty-one patients who underwent
echocardiogram twenty-nine patients had nil to mild regurgitation and
only two patients had moderate regurgitation. The mean gradient at last
follow up was 30.7 mmHg (range 6-120 mmHg), Five of the patients had
RVOT gradients of more than 60 mmHg. One patient had gradient in the
immediate postoperative period due to technical failure and the conduit
was revised prior to discharge. The remaining four patients developed
gradients at a mean follow-up of 60 months. Two of these have under gone
conduit revision and the other two are awaiting re-operation. There was
no significant difference between the degree of regurgitation in the
pulmonary hypertensive and non-hypertensive group at last follow up
(Tabel 4)

\textbf{Discussion}

The quest for an ideal conduit to establish RV to PA continuity began in
1964, when Rastelli et al implanted the first valveless pericardial tube
in a patient with pulmonary atresia. (4) It was soon realised that
competent RVOT has its advantages and Ross et al implanted the first
valved conduit in an eight year old boy with VSD pulmonary atresia. (5)
This was closely followed by Rastelli et al when two children with
transposition of great arteries, VSD and pulmonary stenosis underwent
the eponymous Rastelli's operation. (6) Irradiated cryopreserved aortic
homografts were implanted in all three patients. However, the techniques
of cryopreservation were crude resulting in rapid degeneration of the
homografts. These were replaced by gluteraldehyde preserved porcine
aortic valves mounted in Dacron tube grafts. The midterm outcomes of
porcine xenografts are acceptable but the failure rate at 10 years as
demonstrated by Belli et al was high. (7) The freedom from re-operation
following a Hancock conduit was 98\%, 81\% and 32\% at 1, 5 and 10 years
respectively. (7) By the mid-1980s, the techniques of cryopreservation
process had improved and once again Homografts became the conduit of
choice. Though, homografts had several advantages over Dacron mounted
xenografts, ease of handling being one of them, limited availability in
smaller sizes led to the emergence of another xenograft in the form of
bovine Jugular vein (Contegra, Medtronic Inc). (8,9) The bovine Jugular
vein has a trileaflet valve and it delivered outcomes comparable to
homografts with an added advantage of availability in smaller sizes.
(10) A multi-centre European study by Breymann et al involving 165
Contegra implants found that the results were comparable to homografts.
(11). Another study by Sandica et al involving 444 consecutive
implantation concluded that the bovine jugular veins in RVOT in patients
below 25 years had superior outcomes when compared with cryopreserved
homografts. (10)

The commercially available options to choose from are pulmonary or
aortic homograft, porcine valve in Dacron tube, Porcine valve in bovine
pericardial tube and bovine jugular vein. Though, commercially marketed
conduits are easily available, high cost precludes its wider use in
countries with limited financial resources. The surgeons are often
compelled to use conduits prepared in the operating room from e-PTFE,
Dacron and autologous or bovine pericardium. (12,13) The early and
midterm outcomes of these hand sewn counts have been satisfactory and
comparable with the commercially available options. (14,15)

The majority of the published series with hand sewn conduits have used
PTFE tube graft for the conduit. Our series is perhaps the first where
bovine pericardial sheet is used to construct the conduit. The bovine
pericardium is easy to handle and is haemostatic. One of the drawbacks
of the bovine pericardial conduit is that it calcifies and forms dense
adhesions with the surrounding structures which can complicate the
re-operations. The cost of hand sewn BPCTV is \$300 which is one-sixth
of the cost of commercially available Contegra bovine jugular vein
conduit. This cost advantage makes BPCTV an attractive alternative in
low resource environments. The early and midterm results of BPCTV in our
series were acceptable with freedom from re-intervention of 86\% at 30
months.

\textbf{Limitations}

The larger sample size and a longer follow-up period is required.

\textbf{Conclusion}

This is the first study where hand sewn bovine pericardial conduits have
been used to restore RV to PA continuity. The BPCTV functioned well at
early and midterm follow-up. The presence of pulmonary hypertension had
no impact on the durability of the conduit in early and midterm follow
up. The use of the BPCTV in resource limited locations can be a
reasonable bridge. However, more research with a larger sample size and
a longer follow-up is required.

Source of funding: none to be declared.

Conflict of interest: none to be declared.

Institutional Ethics Committee has approved the study.

\textbf{References}

Kim Dalziel, Li Huang, Akshat Saxena, David S Winlaw. Utilization of
hospital resources by children requiring a right ventricle to pulmonary
artery conduit in the first 10 years of life. J Thorac Cardiovasc Surg
2020;159,Number 1 e73

Huang L, Schilling C, Dalziel KM, Xie S, Celermajer DS, McNeil JJ, et
al. Hos- pital inpatient costs for single ventricle patients surviving
the Fontan procedure. Am J Cardiol. 2017;120:467-72.

Hui-Feng Zhang , Ming Ye, Xian-Gang Yan, Gang Chen, Qi-Lin Tao, and Bing
Jia. (2017). Application of a Simplified Hand-Sewn Trileaflet Valved
Conduit in Right Ventricular Outflow Tract Reconstruction as an
Alternative for Bovine Jugular Vein Graft: Single-Center Experience.
Artificial Organs. 00(00):00--00

Rastelli GC, Ongley PA, Davis GD, Kirklin JW. 1965, Proc. Staff Meet.
Mayo Clin. 40,521

Ross DN, Somerville J. Correction of pulmonary atresia with a homograft
aortic valve. Lancet. 1966;2:1446-7

Rastelli GC, McGoon DC, Wallace RB. Anatomic correction of transposition
of great arteries with ventricular septal defect and sub pulmonary
stenosis. J Thorac Cardiovasc Surg. 1969;58:545-52

Emre Belli, Ece Salihoglu, Bertrand Leobon, François Roubertie, Mohammed
Ly et al. (2010). The Performance of Hancock Porcine-Valved Dacron
Conduit for Right Ventricular Outflow Tract Reconstruction. Ann Thorac
Surg. 89. 152-- 8

Keti Vitanovaa, Julie Cleuzioua, Jürgen Hörera, Jelena Kasnar-Sampreca,
Manfred Vogtb. (2014). Which type of conduit to choose for right
ventricular outflow tract reconstruction in patients below 1 year of
age? European Journal of Cardio-Thoracic Surgery. 46 (6) 1-6

Alsayed Mahmoud Salem. Right ventricle to pulmonary artery connection:
Evolution and current alternatives. (2016). Journal of the Egyptian
Society of Cardio-Thoracic Surgery. 24.47-57

Eugen Sandica, Dietmar Boethig,UteBlanz, Rainer Goerg, Nikolaus Andreas
Haas et al. Bovine Jugular Veins versus Homografts in the Pulmonary
Position: An Analysis across Two Centers and 711 Patients---Conventional
Comparisons and Time Status Graphs as a New Approach.(2016). Thorac
Cardiovasc Surg. 64. 25--35

Breymann T, Blanz U, Wojtalik MA, Daenen W, et al. European Contegra
multicenter study: 7-year results after 165 valved bovine jugular vein
graft implantations. Thorac Cardiovasc Surg EPub. 2009;57:257-69

Koh M, Yagihara T, Umura H, Kagisaki K et al. Long-term outcome of right
ventricular outflow tract reconstruction using a handmade trileaflet
conduit. Our J Cardiovasc Surg. 2005;27:807-14

Iyer KS, Sharma R. The right ventricle to pulmonary artery connection:
When homografts are not always available. Semin Thorac Cardiovasc Surg.
1995;7:145-7

Miyazaki T, Yamagishi M, Maeda Y, et al. Expanded poly-
tetrafluoroethylene conduits and patches with bulging sinuses and
fan-shaped valves in right ventricular outflow tract reconstruction:
multicenter study in Japan. J Thorac Cardiovasc Surg 2011;142:1122--9

Makoto Ando and Yukihiro Takahashi. (2009). Ten-year experience with
handmade trileaflet polytetrafluoroethylene valved conduit used for
pulmonary reconstruction.. The Journal of Thoracic and Cardiovascular
Surgery. 137 (1) 807--814

\textbf{Legend}

Tabel 1 : Diagnosis

ACA: Anomalous coronary artery, APVS: Absent pulmonary valve syndrome,
DOLV: Double outlet left ventricle, DORV: Double outlet right ventricle,
LTGA: l-posed transposition of great arteries, NPH: No pulmonary
hypertension, PH: Pulmonary hypertension, PA: Pulmonary atresia, PS:
Pulmonary stenosis, TA: Truncus arteriosus, TGA: Transposition go great
arteries, TOF: Tetralogy of fallot, VSD: Ventricular septal defect

Tabel 2 : Patient variables

ACC: Aortic cross clamp, CPB: Cardiopulmonary bypass, ICU: Intensive
care unit

Tabel 3 : Conduit construction guideline

A: Width of pericardial sheet, B: Height of the cusp without the free
edge,C: Free edge of the cusp, D: Commisure height, E: Width of the
e-PTFE membrane (A+3), F: Conduit length distal to valve, G: Length of
pericardial sheet ( F and G are variable and are fashioned as per
requirement during implantation)

Tabel 4: Conduit regurgitation at discharge and follow-up

PH: Pulmonary hypertension , NPH: No Pulmonary Hypertension

P value Non significant, Fisher Exact Test

Figure 1 : Construction of bovine pericardial PTFE tri-leaflet valved
conduit

Figure 2 : End-On view of the PTFE tri-leaflet valve\selectlanguage{english}
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\textbf{Hosted file}

\verb`Tabel 1 word.xlsx`  available at \url{https://authorea.com/users/360968/articles/482495-hand-sewn-bovine-pericardial-conduit-with-tri-leaflet-valve-in-right-ventricular-outflow-tract-review-of-41-patients}

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\verb`Tabel 4 word.xlsx`  available at \url{https://authorea.com/users/360968/articles/482495-hand-sewn-bovine-pericardial-conduit-with-tri-leaflet-valve-in-right-ventricular-outflow-tract-review-of-41-patients}

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