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MINISTRY OF EDUCATION AND TRAINING

MINISTRY OF DEFENCE

MILITARY MEDICAL UNIVERSITY

LE THANH KHANH VAN

EVALUATION OF THE TREATMENT
IN RIGHT VENTRICULAR OUTFLOW TRACT
OBSTRUCTION AT CHO RAY HOSPITAL
Speciality: Surgery
Code: 9720104

ABSTRACT OF MEDICAL DOCTORAL DEGREE

HA NOI – YEAR 2019


THESIS COMPLETED AT MILITARY MEDICAL UNIVERSITY
Tutor of thesis:
1. Pham Tho Tuan Anh, Assoc.Prof.PhD.
2. Mai Van Vien, Assoc.Prof.PhD.

Reviewer 1: Nguyen Hoang Đinh, Assoc.Prof.PhD.
Reviewer 2: Hoang Đinh Anh, Assoc.Prof.PhD.
Reviewer 3: Nguyen Huu Uoc, Assoc.Prof.PhD.

The thesis was defended at assembly of the university
on:

o’clock

date

months

year

Can read for this thesis at:
1. National library
2. Military medical university’s library
3. …………………………..


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ABSTRACT
Introduction
Congenital heart disease is one of the central topics that receives a lot
of attention from cardiology, obstetrics and even in society. Pulmonary
stenosis is the narrowing of the exit from the right ventricle, reducing
blood flow to the lungs.
Simple to complex lesions, appear in many pathologies: atrial septal
defect, ventricular septal defect, tetralogy of Fallot, atrioventricular septal
defect, right ventricle double outlet. If we do not fix and treat promptly
and properly, it will lead to unpredictable consequences. Children with
mental and physical delays, always live in severe hypoxia. Patients can die
from complications: acute hypoxia, endocarditis, cerebrovascular
thrombosis, brain abscess, heart failure, low quality of life and reduced life
expectancy. On the contrary, if the patient is treated, especially corrective
surgery to thoroughly expand the right ventricular outlet, it will produce

good results.
The right ventricular enlargement surgery in tetralogy of Fallot
disease or non-tetralogy of Fallot should have the suitable considerations
to preserve the morphology and function of the right ventricular outlet, not
too broad or too narrow, which leads to heart failure later. There are many
characteristics and lesions affect to result to right ventricular enlargement
surgery. So we conducted a research on the topic "Evaluation of the
treatment in right ventricular outflow tract obstruction at Cho Ray
hospital" with two goals:
1. Review some characteristics of pathology right ventricular outflow
tract obstruction for surgical treatment at Cho Ray Hospital in the
period of 2013-2017.
2. Evaluate the results of surgical treatment of right ventricular outflow
tract obstruction at Cho Ray Hospital.
Contributions of the thesis:
1. Determine an overview of congenital heart disease with right
ventricular out flowtract obstruction: physical geometry, anatomical
lesions, treatment approaches.
2. Reflect in part the diversity of the disease with right ventricular out
flowtract obstruction in tetralogy of Fallot, non-tetralogy of Fallot.


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-

Pulmonary artery annulus and main pulmonary artery
dimension in TOF group is smaller in nonTOF group

-

Mortality and complication in TOF group is higher in
nonTOF group.

3. Apply the Z scores to assess the size of pulmonary valve ring,
pulmonary artery and its branches, then suggest surgery method
suitable for different lesions of pulmonary stenosis.
4. Application of surgical methods - a transatrial, transpulmonary artery
approach. Positive results when thoroughly corrected surgical
treatment, especially early repair surgery.
Structure of the thesis:
The thesis consists of 126 pages (excluding references, appendices),
including introduction, 4 chapters (Overview, subjects and research
methods, results, discussion) and conclusions. The thesis includes 38
tables, 14 charts, 33 images. List of references 122 documents (12
Vietnamese articles, 110 English articles).

Chapter 1: OVERVIEW
1.1. A brief history of the studies of congenital heart disease with
pulmonary stenosis
1.1.1. Over the world
- Pulmonary valvular stenosis is one of the common congenital heart
diseases, described by John Baptish Morgagni in 1761.
- In 1888 Etienne Louis Arthur Fallot reported on tetralogy of Fallot
with four characteristics regarding the pathophysiology, including
pulmonary stenosis.
1.1.2. In Vietnam
In 1970, Dang Hanh De was the first Vietnamese who successfully
performed surgery to totally repair tetralogy of Fallot. At the same time,
author Le Ngoc Thanh "research on surgical treatment of pulmonary
valvular stenosis under temporary cessation of circulation at normal

temperature", Nguyen Huu Uoc reports on "research on total surgical
repair of tetralogy of Fallot in older children” is performed at Viet Duc
Hospital, in 2008 Le Quang Thuu" research on total surgical repair of
tetralogy of Fallot "at Hue Central Hospital.


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1.4. Pathophysiological of the right ventricular outflow tract
1.4.1. Abnormal development of pulmonary stenosis
The strict development of the heart step by step over time. This needs to
happen in a proper sequence to avoid abnormalities in function and
structure. Most of the congenital defects in the heart begin with the
combination of many genetic factors related to the family and the effects
of the living environment.
1.4.2. The position pulmonary stenosisi
Right ventricular outflow tract obstruction can occur in a wellcoordinated position in many different locations including: at the
pulmonary valve (valvular stenosis), below the pulmonary valve
(Subvalvar pulmonary stenosis) or just above the pulmonary valve
(Supravalvar pulmonary stenosis).
A. Valvular stenosis: congenital valvular stenosis accounts for 8 - 10% of
congenital heart disease. Damage to the valve often involves trileaflet,
markedly thickened and myxomatous cusps, leading to a narrow center.
B. Subvalvar pulmonary stenosis: Subvalvar pulmonary stenosis is often
seen in association with ventricular septal defect and rarely isolated
subvalvar pulmonary stenosis. The location of the obstruction may be a
discrete fibromuscular ridge/ring or hypertrophied muscle bundles.
Alternatively, hypertrophied supporting bands of the right ventricle may
occur, resulting in dividing the right ventricle into two chambers.
C. Supravalvar pulmonary stenosis: Supravalvar pulmonary stenosis
can be isolation, pulmonary trunk stenosis or pulmonary artery branches

stenosis. It accounts for 2-3% of congenital heart disease, is often
complicated, on both sides, and spreads into the mediastinum or lung
hilum, which is common in tetralogy of Fallot.
1.5. Congenital heart diseases with right ventricular outflow tract
obstruction
Right ventricular outflow tract obstruction may occur in many congenital
heart diseases, divided into two groups: right ventricular outflow tract
obstruction in tetralogy of Fallot (TOF) and right ventricular outflow tract
obstruction in non-tetralogy of Fallot (non-TOF).
1.5.1. Right ventricular outflow tract obstruction in tetralogy of
Fallot: Tetralogy of Fallot includes right ventricular outflow tract


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obstruction, a large ventricular septal defect, right ventricular hypertrophy
and an overriding aorta.
1.5.1.1. Anatomic defects
a. Infundibulum
The shift to the left, up and front of the infundibulum or infundibular
septum causes right ventricular out flow tract obstruction, leading to
obstruction under pulmonary artery. The subpulmonary infundibulum is
too small, it cannot fill the space above the ventricular septum and septal
band, resulting in a ventricular septal defect. Failure of normal
morphogenetic movement of the infundibular septum to occur results in
aortic overriding. The stretching of the right ventricular free wall or the
ventricular septum contributes to the pulmonary stenosis.
Therefore, author Van Praagh suggested the tetralogy of Fallot
basically is a “monology”, just 1 anomaly, namely, underdevelopment of
the subpulmonary infundibulum and its sequelae.
b. Pulmonary valve in tetralogy of Fallot: According to Kirklin

narrowing Pulmonary valve occurs about 75% of tetralogy of Fallot cases,
50% - 75% are bicuspid valves, 5% do not have pulmonary valve. Narrow
valves are often caused by dysplasia and no separation of bicuspid valve,
ligature on the valve or a combination of the above factors.
c. Pulmonary trunk and its branches in tetralogy of Fallot: Pulmonary
trunk is usually smaller and shorter than usual. The narrowest part
pulmonary trunk is usually at the junction of the sinus tube. The arterioles
in the lobules of the lungs may be smaller than normal with the thin
middle layer, due to low vascular pressure or lack of blood to the lungs.
1.5.2. Right ventricular outflow tract obstruction in non-tetralogy of
Fallot
Right ventricular out flow tract obstruction with atrial septal defect or
ventricular septal defect, or isolated right ventricular outflow tract
obstruction.
1.5.3. Right ventricular outflow tract obstruction with complex
congenital heart diseases
- Complete atrial-ventricular canal
- Double outlet right ventricle
1.6. Diagnose


7
1.6.1. Clinical
a. Tetralogy of Fallot: Patients may manifest: cyanosis, heart murmur,
finger clubbing, easy tiring, shortness of breath, and physical and mental
developmental delay. Cardiovascular: normal T1, decreased or inaudible
T2, arrhythmia. A harsh grade 2/6 to 5/6 systolic ejection murmur rib cage
II - III near the left side of the sternum spreading behind the back.
b. Right ventricular out flowtract obstruction in non-tetralogy of
Fallot disease: Severe stenosis, early clinical symptoms, severity depends

on degree of stenosis. However, in mild patients there is no clear
symptom, accidentally discovered during physical examination periodic
health. Sometimes it is found in other congenital syndromes.
1.6.2. Diagnostic Tests
a. Cardiopulmonary X-ray: The majority of patients have normal
heart size, small pulmonary trunk: an ax-shaped sign. The abnormal
"coeur-en-sabot" (boot-like) appearance of a heart due to the right
ventricular hypertrophy. Lung circulation is reduced: the two pulmonary
hilum are less dark than usual.
b. Electrocardiogram: there is increased right axis deviation from
right ventricular hypertrophy with associated high amplitude Rs waves in
V1, then accidentally rS from V2 to V6. Branches are blocked
incompletely.
c. Echocardiography: A definitive diagnosis and diagnosis of
accompanied lesions.
1.7. Treatment of right ventricular outflow tract obstruction
1.7.1. Medical treatment
Mainly temporary treatment and prevention of complications.
1.7.2. The index for evaluating the severity of right ventricular outflow
tract obstruction
a. Differential pressure through valve pulmonary artery
In clinical, based on the pressure difference through pulmonary valve
(pressure difference between right ventricle - pulmonary artery). 4 levels
of severity and based on which to give indications for treatment, or follow
the progress of the disease, or the post-surgical results.
+ Normal or negligible: pressure difference between right ventricle pulmonary artery <25 mmHg.


8
+ Light narrow: pressure difference between right ventricle pulmonary artery: 25 - 49 mmHg.

+ Medium narrow: pressure difference between right ventricle pulmonary artery: 50 - 79 mmHg.
+ Severe narrowing: pressure difference between right ventricle pulmonary artery: ≥ 80 mmHg.
b. Index
* Z scores (Z value, Z score) is the application value for calculating
the size of different heart structures.
Measured size - average normal size
Z=
Standard deviation around average size
Calculating Z to decide the size of the heart structure is suitable for
one or two phase repair surgery, to decide the surgical techniques and to
evaluate disease prognosis.
1.7.3. Surgical treatment of right ventricular outflow tract obstruction
in tetralogy of Fallot
a. Indications: Total or temporary surgical repair based on various
factors:
• pulmonary stenosis failed with balloon valvuloplasty.
• Dysplastic pulmonary valve
• Severe subvalvar pulmonary stenosis or supravalvar pulmonary
stenosis.
• Pulmonary stenosis accompanied by other congenital heart defects.
b. Temporary surgery: The main purpose is to increase the blood
flow to the lungs by creating an outflow tract of aorta or its branches to
pulmonary artery to partially improve chronic hypoxia, simultaneously
over time, the pulmonary artery system can stretch out gradually.
+ Blalock - Taussig surgery: bridge subclavian artery - pulmonary
artery.
+ Waterston surgery: bridge ascending aorta - pulmonary artery
+ Potts surgery (Willis Potts): bridge descending thoracic aorta - left
pulmonary artery
c. Total surgical repair: Pathological treatment of right ventricular

outflow tract obstruction is a total repair of defects in the heart, complete
reconstruction
of
anatomy,
physiology,
and
corresponding
pathophysiology with the support of extracorporeal circulation.


9
Chapter 2: SUBJECTS AND METHODS OF RESEARCH
2.1. Research subjects
2.1.1. Selection criteria: Patients with a definitive diagnosis of pulmonary
stenosis include tetralogy of Fallot and non-tetralogy of Fallot (atrial
septal defect, ventricular septal defect, right ventricular outflow tract
obstruction isolated). These patients had undergone the total surgical
repair at the Department of cardiac resuscitation, Cho Ray Hospital from
May 2013 to May 2017.
2.1.2. Exclusion criteria
- Cases of dysplastic pulmonary artery (Pulmonary Atresia).
- Pulmonary stenosis with aorta displacement, dysplastic right
ventricle, dysplastic left ventricle, and toal atrioventricular septal defect.
2.2. Research Methods
2.2.1. Research design: The thesis uses description method with noncontrolled group.
2.2.2. Sample size and subgroup: Convenient study sample size, 75
patients divided into two groups: right ventricular outflow tract obstruction
in tetralogy of Fallot and non-tetralogy of Fallot.
2.3. Process of implementation
2.3.1. Diagnostic procedure: Diagnosis is based on history, clinical

symptoms and laboratory tests
2.3.2. Surgical procedure
- The procedure of anesthesia: The patient is pre-operative
examination before surgery. Intubation, controlled ventilation with
mechanical ventilator.
- Surgical method: Open the chest along the vertical line between the
sternum. Establish extracorporeal circulation.
Transverse clamping of the aorta, the solution causing heart paralysis
is transmitted with blood to protect the heart muscle through aortic root,
the heart stopped beating completely and repeats every 25 minutes.
Open the right atrium, parallel and away from the atrioventricular
groove about 10 mm and open along the pulmonary artery trunk. Through
the patent foramen ovale (or create an atrial septal hole) place a suction
tube towards the heart lung machine to empty the left heart chamber.


10
Repair the whole damage: patch ventricular septal defect, widen the
right ventricular outflow tract.
Warm the patient slowly to normal temperature, close the heart
opening lines with prolene suture, filling and expelling the air.
Remove the clamp of the aorta for the heart to beat again.
Measure the pressure of the heart chambers directly at the positions:
right ventricle, funnel part and pulmonary artery trunk, by directly
inserting the needle into the position to be measured and connecting to the
pressure gauge to determine the pressure difference through the narrow
part of the right ventricular outflow tract. Ideally:
Pressure ratio right ventricle / left ventricle ≤ 0.7, differential pressure
right ventricle - pulmonayry artery ≤ 30mmHg
Put temporary electrodes at the atria and ventricles.

Place chest drainage: mediastinum and pericardium.
Thoroughly stop bleeding, especially the incision into the heart.
Chest closure by layers.
2.3.3. Resuscitation procedure: Patients continue to breathe
mechanically, routine tests.
2.5. Result evaluation
We evaluate the total repair results based on 3 aspects:
a. Clinical and subclinical improvement
Evaluate the results of widening the right ventricular outflow tract
must be according to the pressure difference between right ventricle pulmonary artery.
* Difference between right ventricle - pulmonary artery <30 mmHg: good.
* 30 mmHg ≤ difference between right ventricle - pulmonary artery ≤ 50
mmHg: average.
* Difference between right ventricle - pulmonary artery > 50 mmHg: bad.
b. Complications during and after surgery
Post-surgical bleeding, cardiac arrhythmia, reduced cardiac output, air
filled cavity, pleural fluid, collapsed lung, diaphragmatic paralysis, kidney
failure, infection.
Evaluate the results of pulmonary valve: valve opening rate, residual
narrowing rate, residual ventricular septal defect.
c. Post-surgical Death

Chapter 3: STUDY RESULTS


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During 05/2013 to 05/2017, in Cho Ray Hospital we recorded 75
patients with congenital heart disease with right ventricular outflow tract
obstruction, including 47 (62.7%) women and 28 (37.3%) men. General
results and results according to the group of narrow right ventricular

outflow tract in Tetralogy of Fallot (TOF) and non-TOF are as follows.
3.1. Grouping patients
Table 3.1. Percentage of patients with lesions (n = 75)
Congenital heart disease

Frequency Percentage (%)

Tetralogy of Fallot (tetralogy of Fallot)

59

78,7

Pulmonary stenosis and atrial septal defect

7

9,3

Pulmonary stenosis and ventricular septal defect

5

6,7

Pulmonary stenosis isolated

4

5,3

3.2. Characteristics of patients with right ventricular outflow tract
obstruction
3.2.1. General characteristics
Table 3.2. Characteristics of age, weight, BSA of patients(n=75)
General characteristics
Variables

Median

SD

Min

Max

Age
Weight(kg)
BSA(m2)

6
22
0,8

15,5
18,9
0,5

1
6,5

0,3

47
65
1,7

Subgroup characteristics
TOF
Non-TOF
M(SD)
M(SD)
15,3(15,5)
20,1(15,3)
26,5(18,9)
33,5(18,2)
0,9(0,5)
1,1(0,5)

M: medium, SD: standard deviation, Min: minimum, Max: maximum

3.2.2. History of B - T shunt
Table 3.3. Percentage of B - T shunt before operation of patients in
tetralogy of Fallot and non-tetralogy of Fallot
B-T shunt trước mổ
Yes
No

TOF
n(%)
7(11,9)

52(88,1)

Non-TOF
n(%)
0(0)
16(100)

3.2.3. Clinical characteristics before surgery
Table 3.4. Clinical characteristics before operation (n=75)


12
General characteristics
ClinicalManifestation
Frequency
s
Cyanosis
64
Finger clubbing
21
Episodes of cyanosis
8
NYHA
Stage II
60
Stage III
15

Subgroup characteristics
TOF

Non-TOF
Percentage(%)
n(%)
n(%)
85,3
57(96,6)
7(43,8)
28
21(35,6)
0(0)
10,7
8(13,6)
0(0)
80
20

45(76,3)
14(23,7)

15(93,8)
1(6,3)

Table 3.5. SpO2 of patients before operation (n=75)
General characteristics
Variables
M
SD Min
SpO2 before surgery
84,4 7,1 70

Max
99

Subgroup characteristics
TOF
Non-TOF
82,9(6,4)
89,9(6,8)

M: medium, SD: standard deviation, Min: minimum, Max: maximum

3.2.4. Paraclinical characteristics before operation
3.2.4.1. Hemodynamic changes
Table 3.6. Hemodynamic tests before operation (n=75)
Variables
The red blood cell
counts (x1012/l)
Hemoglobine (g/l)
Hct (%)
The platelets
counts (x109/l )

M
5,9

General characteristics
Median SD Min
5,6
1,3
3,7

155
48,4
267,8

153
46,6
260

30,2
10
96,3

93,3
29,8
36

Subgroup characteristics
Max
TOF
Non-TOF
10,2
6,3
4,8
(1,2)
(0,7)
233 162,3(29)
128(15)
71,4
51 (9,5)

38,9 (4,7)
535
264,9
278,4
(103,1)
(67,1)

M: medium, SD: standard deviation, Min: minimum, Max: maximum

3.2.4.2. Echocardiogram results
a. The severity of right ventricular out flowtract obstruction and heart
function
Table 3.7. Doppler echocardiography before operation (n=75)


13
General characteristics
Index

M

Median

SD

Min

Pressure
Difference
Z score

PA
MPA
LPA
RPA
Ejection
Fraction

89,8

90

24,2

41

-2,2
-2,1
0,3
0,3
69,3

-1,7
-2,2
0,5
0,3
70

2,6
2,8
2,1

1,7
5,8

-6,8
-6,9
-4,2
-3,7
56

Subgroup characteristics
TOF
Non-TOF
Max
M(SD)
M(SD)
174
94,3(41)
88,5(17,4)
3,6
5,5
5,8
4,8
81

-2,68(2,5)
-2,9(2,2)
0,1(2,1)
-0,01(1,6)
69,5(5,6)

-0,5(1,96)
0,7(3)
1,1(1,8)
1,3(1,8)
68,6(6,6)

M: medium, SD: standard deviation, Min: minimum, Max: maximum

b. The quantity of narrowed positions of right ventricular outflow
tract
Table 3.8. The quantity of narrowed positions of right ventricular outflow
tract (n=75)
General characteristics
The quantity of
narrowedpositions
Frequenc
of right
y
ventricular
outflow tract
1 position
17
2 positions
34
3 positions
24

Subgroup characteristics
Percentage(%
)

TOF
n(%)

Non-TOF
n(%)

22,7
45,3
32

8(13,6)
27(45,8)
24(40,7)

9(56,3)
7(43,8)
0

3.3. Characteristics of surgery
3.3.1. Time of extracorporeal circulation and time of aorta clamping
Table 3.9. Time of extracorporeal circulation and time of aorta clamping
(n=75)
General characteristics
Variables
M Median SD Min
(minute)
Time of
extracorporeal 129,9
130

40,4 40
circulation
Time of aorta
96,6
100
30,8 30
clamping

Max

Subgroup characteristics
TOF
Non-TOF
M(SD)
M(SD)

300

140,7
(35,5)

90,1
(32,4)

180

106,3
(23,8)

60,9

(27,4)

M: medium, SD: standard deviation, Min: minimum, Max: maximum


14
3.3.2. Characteristics of Techniques
Table 3.10. Characteristics of Techniques (n=75)
General characteristics

Subgroup characteristics
Percentage
Frequency
(%)

Techniques

Open right ventricle and pulmonary
trunk
The incision of pulmonary valve
. incision of pulmonary valve 0,5cm
. incision of pulmonary valve for
creating Monocusp
Open additional funnel-shape right
ventricle (infundibulum)
Repair tricuspid valve

TOF
n(%)

Non-TOF
n(%)

75

100

11
5

14,7
6,7

10(17)
4(6,7)

1(6,3)
1(6,3)

6

8

6(10,2)

0

5

6,7

5(8,5)

0

11

14,7

6(10,2)

5(31,3)

3.3.3. Pressure and pressure difference through pulmonary artery
after removing extracorporeal circulation
Table 3.11. Pressure of heart chambers after removing Extracorporeal
circulation (n = 75)
General characteristics
Pressure

Pressure Difference
The ratio of right
ventricle/left ventricle

Subgroup characteristics

M

Median

SD

Min

Max

TOF
M(SD)

Non-TOF
M(SD)

15,9

15

11,2

0

59

16,7(11,5)

13,1(9,6)

0,6

0,6

0,1

0,3

0,8

0,6(0,1)

0,5(0,1)

M: medium, SD: standard deviation, Min: minimum, Max: maximum

3.4. Characteristics of surgery
3.4.2. Time of mechanical ventilation, ICU and post-operation
Table 3.13. Time of mechanical ventilation, ICU and post-operation (n=75)
General characteristics
Subgroup characteristics
Variables

Time of mechanical
ventilation (hour)
Time of ICU (hour)
Time post-operation(day)

Median

SD

Min

Max

TOF
M(SD)

Non-TOF
M(SD)

15

50,7

4,8

360

29,7(56,7)

13,3(6,1)

48
9

74,7
4,7

14
1

480

27

71,6(82,3)
10,9(4,9)

41,1(24,2)
9,4(3,4)

M: medium, SD: standard deviation, Min: minimum, Max: maximum

3.7. The correlation between the severity of right ventricular outflow
tract obstruction with complications


15
3.7.1. The correlation between pressure difference through pulmonary
artery with time of mechanical ventilation, sympathomimetic drug,
complications of pericardial effusion, pleural effusion.
Table 3.20. The correlation between pressure difference through pulmonary artery
before surgery with complications of pericardial effusion, pleural effusion.
Pressure difference through pulmonary valve in
echocardiography before surgery
Complications
Total population n=75
TOF n=59
M
SD
M
SD
Yes

94,3
19,2
92,4
15,8
No
87,4
26,9
86,1
18,7
P
0.17
0,19
* Mann –Whitney test

3.7.2. The correlation between the pressure ratio of right ventricle/ left
ventricle with time of mechanical ventilation, sympathomimetic drug,
complications of pericardial effusion, pleural effusion.
Table 3.21. The correlation between the pressure ratio of right ventricle/ left
ventricle with sympathomimetic drug

Vasopressors
Not use
1 vasopressor
2 vasopressor
3 vasopressor
P

The pressure ratio of right ventricle/left ventricle
Total population n=75
TOF n=59

M
SD
M
SD
0,5
0,1
0,6
0,1
0,6
0,1
0,6
0,1
0,6
0,1
0,6
0,1
0,7
0,1
0,6
0,1
0.76*
0.93*

* Kruskal-Wallis test

3.7.3. The correlation between the number of narrowed positions with
time of extracorporeal circulation, time of aorta clamping, time of
mechanical ventilation, sympathomimetic drug and complications of
pericardial effusion, pleural effusion.
Table 3.24. The correlation between the number of narrowed positions

with time of extracorporeal circulation
The number
of narrowed
positions
1 position
2 positions
3 positions

Time extracorporeal circulation
Total population n=75
TOF n=59
M
SD
M
SD
109,7
37,2
137,3
30,9
127,7
31,3
135,8
21,9
147,4
47,6
147,4
47,6


16

P

0.01

0.82

*Kruskal Wallis test

Table 3.25. The correlation between the number of narrowed positions
with time of aorta clamping
The number
of narrowed
positions
1 position
2 position
3 position
P

Time of aorta clamping
Total population n=75
TOF n=59
M
SD
M
SD
82,3
35,9
110
31,7
95

28,2
102,7
19
109,1
26,2
109,1
26,2
0.02
0,58

3.8. Results after hospitaliztion
Table 3.32. Pressure Difference through pulmonary valve, ejection fraction
of left ventricle (n=73)
General characteristics
Variables

M

Median

SD

Min

Pressure difference
through pulmonary
valve
Ejection fraction

22,7

66,2

18
66,5

12,1
6,6

4,5
53

Subgroup characteristics
TOF
Non-TOF
Max
M(SD)
M(SD)
50
84

22,5 (11)

23,5(14,5)

M: medium, SD: standard deviation, Min: minimum, Max: maximum

Table 3.33. Residual ventricular septal defect, tricuspid valve
regurgitation, pulmonary valve regurgitation (n=73)
General characteristics
Complications

Frequency

Residual ventricular
septal defect
Tricuspid valve
regurgitation
Pulmonary valve
regurgitation

10

Subgroup characteristics
TOF
Non-TOF
Percentage(%)
n(%)
n(%)
13,7
8(14)
2(12,5)

8

11

2

2,7

4(7)

4(25)

1(1,8)

1(6,3)


17
Chapter 4: DISCUSSION
4.1. Patient groups
In the study of congenital heart disease with narrow right ventricular
outflow tract, we generally evaluated the whole narrow right ventricular
outflow tract disease and separated them into 2 groups of narrow right
ventricular outflow tract in TOF and narrow right ventricular outflow tract
in non-TOF.
Our study accounts for the majority: 78.7% (n = 59 patients) with right
ventricular outflow tract obstruction in TOF (Table 3.1). In non-TOF: 21.3% (n
= 16).
+ Right ventricular outflow tract obstruction and ventricular septal
defect (VSD): 6.7% (n = 5)
+ Right ventricular outflow tract obstruction and atrial septal defect
(ASD): 9.3% (n = 7)
+ Single right ventricular outflow tract obstruction: 5.3% (n = 4)
4.2. Characteristics of patients with right ventricular
outflow tract obstruction
4.2.1. Gender, age, weight and body surface area
In our study in Cho Ray Hospital, there were 75 patients, women
accounted for 62.7% (47 patients) and men 37.3% (28 patients), the rate of

female patients was nearly double that of men.
The mean age of all patients during the study was 6 ± 15.5 years (from
8 months to 47 years). The mean weight of patients: 22 ± 18.9 kg (from 6.5
to 65 kg). The mean body surface area is 0.8 ± 0.5 m2 (Table 3.2).
But when considering 2 groups of patients with Narrow right
ventricular outflow tract in TOF and non-TOF diseases, the mean age of
patients in TOF: 15.3, weight: 26.5 and BSA: 0.9. Results were lower than
non-TOF patients whose age: 20.1, weight: 33.5 and BSA: 1.1 (Table 3.2).
4.2.2. B - T shunt (Blalock-Taussig shunt)
In the study, 11.9% of patients were temporarily operated with B-T
shunt; This case is in TOF disease (Table 3.3). Report by Nguyen Hoang
Dinh: 3.9%, Nguyen Huu Hieu: 35.7%.
4.2.3. Clinical characteristics before surgery


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a. Functional symptoms through NYHA (New York Heart Association)
classification: Table 3.4 shows that all patients classified NYHA II had
the highest rate of 80%, NYHA III patients were 20%. Results in the TOF
group with 76.3% of patients classified NYHA II, 23.7% of patients
classified NYHA III. Patients have been tired mainly due to chronic
hypoxia.
b. Cyanosis:
Sign of cynosis often appear, may appear early 2 months postpartum
and gradually increase in patients with severely narrow right ventricular
outflow tract. Patients in surgery had relatively high cynosis symptoms
(85.3%).
The group in TOF with sign of cynosis accounted for 96.6%, while
the group in non-TOF without sign of cynosis 43.8% (Table 3.4). The level
of cynosis is related to the amount of HC, Hct, Hb in blood and blood

oxygen saturation.
c. Episode of cynosis when making every effort: Cynosis with
syncope (often accompanied by severe cynosis and syncope), among 75
patients, the incidence of cynosis is 10.7%. All cases of cynosis were
narrow right ventricular outflow tract in TOF disease, showing severe
hypoxia when the ventricular funnel must be narrow and suddenly
constricted.
d. Drumstick finger: In general, there were 28% of patients in the
study with cynosis signs. Particularly, in 59 patients (n=59) in TOF had
35.6% of drumstick fingers, while in 16 patients without TOF (n=16) there
was no patients had drumstick fingers (Table 3.4).
4.2.4. Hematological characteristics and oxygen saturation before
operation
4.2.4.1. Hematology
The number of HC, Hb and Hct in patients with narrow right ventricular
outflow tract were increased due to the adaptation over time with chronic
hypoxia. Table 3.6 shows the number of HC: 5.9 ± 1.3 x1012 / l, Hb: 155
± 30.2 g / l and Hct: 48.4 ± 10%.
For the group of narrow right ventricular outflow tract in TOF, the mean
number of HC, Hb, Hct was 6.3 x1012 / l, 162.3 g / l and 51%,


19
respectively, were higher than those of patients with narrow right
ventricular outflow tract in non-TOF.
4.2.4.2. Oxygen saturation:
The oxygen saturation in the artery of preoperative patients was 84.4 ±
7.1, especially, the number of patients with right ventricular outflow tract
obstruction in TOF was even lower: 82.9 ± 6.4 (Table 3.5).
4.2.5. Pathological characteristics of right ventricular outflow tract

obstruction:
4.2.5.1. Level of right ventricular outflow tract obstruction
a. Size of pulmonary artery
The Z score of the pulmonary artery valve was -2,2 ± 2,6, the Z score
of the pulmonary artery trunk was -2.1 ± 2.8 (Table 3.7). Therefore, there
are many cases where patients need to expand their pulmonary artery trunk
to match the ideal size according to their age and weight.
In patients of the TOF group, there is a relatively small Z-score: Z
score of the pulmonary artery valve was -2.68, Z score of the pulmonary
artery trunk was -2.9 (Table 3.7), which was smaller than the Z score at the
corresponding positions for patients belonging to the group of non TOF: Z
score of pulmonary artery valve was -0.5, Z score of the pulmonary artery
trunk was 0.7. Narrow right ventricular outflow tract in TOF is always
severe, complex, narrow in many locations.
b. Different pressure between right ventricle - pulmonary artery
Different pressure between right ventricle-pulmonary artery was 89.8 ±
24.2 mmHg (Table 3.7). The difference between the right ventricle and
pulmonary artery was the value that reflects the serious condition of
disease, the time and the degree of the narrow right ventricular outflow
tract.
When considered separately, in the group of 59 patients with narrow
right ventricular outflow tract in TOF, the difference was 94.3 mmHg,
which was higher than in the group of 16 patients with narrow right
ventricular outflow tract in non-TOF (88.5 mmHg).
4.2.5.2. The number of narrow lesions of right ventricular outflow
tract:


20
In the study (Table 3.8), when calculating the general rate of narrow

position and combination of narrow positions, we found that narrowed 2
positions: 45.3%, narrowed 3 positions: 32%, while narrowed 1 position:
22.7%. With TOF and non-TOF group, the proportion of patients with 2
and 3 narrowed positions in the TOF group was 45.8% and 40.7%,
respectively.
4.3. Characteristics of surgical process
4.3.1. Time of extracorporeal circulation and time of aortic clamping
In our study (Table 3.9): the time of aortic clamping was 96.6 ± 30.8.
The longer the clamping time, the longer the duration of myocardial
anemia. The time of extracorporeal circulation was 129.9 ± 40.4, quite
long compared to the time of surgery.
Most of the time of extracorporeal circulation was prolonged in
patients with TOF because of the difficulty level and many injuries needed
to be repaired, so the result of the mean time of extracorporeal circulation
in patients with TOF was 140.7 minutes, in patients without TOF is 90.1
minutes. The mean time of aortic clamping in patients with TOF and nonTOF is 106.3 and 60.9 minutes, respectively.
4.3.2. Surgical specification
4.3.2.1. Narrow right ventricular outflow tract in TOF
a. Road approaching:
All 75 patients (100%) with narrow right ventricular outflow tract in
this study had surgery to approach the lesions through opening the
pulmonary artery trunk and right atrium.
b. Solving pulmonary valve rings:
Do not keep the valve ring during the expansion of the right
ventricular outflow tract. We cut through the valve ring. The ratio of the
cut valve in the study with a sample of 75 patients (Table 3.10) was
14.7%, this result was less with the mention of Robert M Freedom (24%)
using transaortic valve patch or results of many other reports of transaortic
valve patch from 20 to 80%, more than 50%.
If we try to retain the valve ring when it is impossible to remain

narrowed, causing the overload of right ventricular pressure, there is a risk


21
of right ventricular anemia, right heart failure, open tricuspid valve,
threatening patient's life.
We only cut the valve ring around 0.5 cm: 6.7%, which means to
preserve the maximum valve ring.
There were 6 patients (8%) who were performed the monocusp and
all cases were narrow right ventricular outflow tract in TOF (6 patients),
there were no cases in non-TOF performed the monocusp (Table 3.10).
c. Complexly narrow, multiple positions:
In case of complexly narrow right ventricular outflow tract, many
positions are narrow, and the high number of undeveloped ventricular
funnels. We opened the right funnel with a very low rate: 6.7%. This rate
was found in the group of narrow right ventricular outflow tract in TOF
4.3.2.2. Right ventricular outflow tract obstruction in non TOF
a. Expanding right ventricular outflow tract: right ventricular outflow
tract obstruction in the group of non-TOF was mostly at 1 position: 56.3%, so
the expansion was simpler and similar to the group in TOF.
b. Closing atrial septal defect, ventricular septal defect and patent
foramen ovale: according to our statistics, the narrowing rate of right
ventricular outflow tract with atrial septal defect was 9.3% (Table 3.1). All
holes in atrial septal defect, ventricular septal are fully closed.
4.3.3. Evaluate the results of surgery to widen right ventricular
outflow tract obstruction
Our results (Table 3.11) showed that pressure difference between right
ventricle - pulmonary artery during surgery after repairing the whole
lesion and discontinuing extracorporeal circulation was 15.9 ± 11.2. Right
ventricle / left ventricle pressure ratio is 0.6 ± 0.1

When seen separately in two groups of right ventricular outflow tract
obstruction in TOF and non-TOF, differential pressure through pulmonary
artery valve, the rate of right ventricle / left ventricle pressure in patients
with TOF was 16.7 and 0.6 which were higher in non-TOF patients, 13.1
and 0.5 (Table 3.11).
4.4. Postoperative characteristics
4.4.1. Vasopressors after surgery


22
In Table 3.12, the percentage of not using vasopressors: 13.3%, using
one type of vasopressor accounts for the largest proportion: 69.4%
Nearly all patients who need to use 2 and 3 types of vasopressors were
in group of narrow right ventricular outflow tract in TOF (Table 3.12).
4.4.2. Time for mechanical ventilation, lying ICU and postoperative
lying
The mean mechanical ventilation time (Table 3.13, Figure 3.8) was 15
hours. Mean resuscitation time was 48 hours, which was the average time
for all recovery and stability of patients.
In patients with right ventricular outflow tract obstruction in TOF, the
above times are longer than those of non-TOF patients.
4.5. Early death
4.5.1. Complications after operation
In our study, there were 30 patients with early complications after
operation, accounting for 41% (Table 3.14). Of which 21.9% was pleural
effusion, 15.07% was pericardial effusion. All just need medical and
physical therapy.
Complication of bleeding after surgery was 2.7% and re-surgery to
stop hemostasis behind the sternum around the fourth hour after surgery,
no clear bleeding points, mainly from the sternum section.

There was one case (1.4%) which did not heal the sternum, it was
necessary to close the sternum on day 20th.
When observed in the pathological group (Table 3.14), the
complications occurred much in TOF, in which the rate of complication of
pleural effusion was 26.3%, while in patients without TOF was only 6.3%.
The rate of complication of pericardial effusion in TOF group was 15.8%,
non-TOF group was 12.5%. The incidence of bleeding complications and
sternal dehiscence were similar in patients in TOF at 3.5% and 1.8%,
respectively;
4.5.2. Early death
Two female patients (2.6%) died early after total repair of TOF.
4.7. The relationship between degree of the narrow right ventricular
outflow tract. and the complications.


23
4.7.1. The relationship between pressure difference through
pulmonary artery valve with the duration of mechanical ventilation,
vasopressor, complications of pleural effusion and pericardial
effusion.
The results of our study: There was no statistically significant
correlation between the degree of pressure difference through the
pulmonary valve with vasopressor, fluid perfusion complications.
4.7.2. The Relationship between the pressure of right ventricle / left
ventricle and vasopressor, complications of pleural effusion and
pericardial effusion.
The ratio of right ventricle / left ventricle pressure in patients using three
vasopressors was higher than in other patients, but not statistically
significant.
4.7.3. The relationship between narrow position and surgery time,

vasopressors
The duration of extracorporeal circulation and aortic clamping in
patients with three-position lesions were longer than in patients with two
or one position (Table 3.24 and 3.25), it was statistically significant.
4.7.4 The relationship between Z score with mechanical ventilation
duration, complications of pleural effusion and pericardial effusion.
The lower the Z score of pulmonary valve ring, the more likely the
complications of pleural effusion and pericardial effusion, this correlation
was not statistically significant (Table 3.30).
Similarly, the lower the Z score of the pulmonary artery trunk, the more
likely the complications of pleural effusion and pericardial effusion,
especially this correlation was statistically significant (Table 3.31).
4.8. Results after hospitalization
4.8.1. Postoperative duration
The mean postoperative duration of all patients (including 2 deaths)
was 9 ± 4.7 days. This time in patients with narrow right ventricular
outflow tract in TOF was longer than the others 1 day (Table 3.13).
4.8.2. Echocardiogram results
- Differential pressure through pulmonary valve: the mean was 22.7 ±
12.1 mmHg (Table 3.32). Thus, the pressure difference at the time of


24
discharge was slightly higher than the direct measurement immediately
after stopping extracorporeal circulation, but much lower than before
surgery.
The mean difference of postoperative pressure through the valve in
patients with narrow right ventricular outflow tract in TOF was 22.5, in
patients without TOF was 23.5, which was reduced considerably.
- Tricuspid valve: according to Table 3.33, the degree of tricuspid

valve regurgitation more than 2/4 accounted for 11%. Severe tricuspid
valve regurgitation appears soon after surgery.
- Pulmonary valve: the degree of pulmonary valve regurgitation at 3/4
accounted for 2.7%, due to physical injury.
- Persistent ventricular septal defect: 10 cases with ventricular septal
defect persistence, accounting for 13.7% of the total. Most of the
ventricular septal defect persistence in patients with narrow right
ventricular outflow tract in TOF was 8 patients (14%), while in non-TOF,
there were 2 patients (12,5%) (Table 3.33).

CONCLUSION
Through this study for all 75 congenital heart patients with the right
ventricular outflow tract obstruction, dividing into 2 subgroups of
tetralogy of Fallot and without tetralogy of Fallot which had undergone
total surgical repair at Cho Ray hospital, we would like to give the
following conclusions:
1. Pathophysiologic characteristics of narrowing of the right
ventricular outflow tract
The right ventricular outflow tract obstruction has a diverse
manifestation in clinical lesions from simple to complex.
Female is 62.7% and 37.3% more than male in cyanosis, finger
clubbing makes up a high rate: 85.3% and 28%, most of heart failure is
NYHA II: 80%, low oxygen saturation with SpO2: 84.4%.
Hematologic testing is therefore highly diversified: the number of
erythrocytes, Hemoglobin and Hematocrit increase.
The number of narrow positions spreads widely: 2 positions: 45.3%, 3
positions: 32%, the size of the valve and the small pulmonary trunk. The


25

rate of narrowing of the right ventricular outflow tract in tetralogy of
Fallot is 78.7%. Pressure difference between right ventricle - pulmonary
artery: 89.8 mmHg, B - T shunt: 9.3%.
The right ventricular outflow tract obstruction in patients with
Tetralogy of Fallot, cyanosis and finger manifestations were much higher
than in patients with the right ventricular outflow tract obstruction in nonTetralogy of Fallot with the following rates 96.6%, 35.6% compared to
43.8%, 0%. SpO2 in the Tetralogy of Fallot group was lower in the nonTetralogy of Fallot group.
In the Tetralogy of Fallot group, the rate of 2 narrowed positions and
3 narrowed positions are 45.8% and 40.7% respectively, more than 43.8%
and 0% in the non-Tetralogy of Fallot group
The size of the valve and pulmonary trunk in the tetralogy of Fallot group
is smaller than that in the non-Tetralogy of Fallot group with the Z-index
of pulmonary valve = -2,68, Z of pulmonary trunk = - 2.9 compared to Z =
- 0.5, 0.7. Pressure difference between right ventricle - pulmonary artery:
94.3 mmHg higher than 88.5 mmHg.
2. The results of surgery to repair the narrowing of the right
ventricular outflow tract
Surgical methods to correct the narrowing of the right ventricular
outflow tract and other accompanied lesions are safe and effective.
Using completely the incision through the right atrium and the aorta
to approach lesions, the ratio of preserving the pulmonary valve is 85.3%.
After repairing and expanding the right ventricular outflow tract as
required, measure the pressure difference between right ventricle pulmonary artery: 15.9 mmHg and pressure ratio between right
ventricle/left ventricle: 0.6. Reasonable length of time for aorta clamping
and extracorporeal circulation: 96.6 minutes, 129.9 minutes. Time for
mechanical ventilation, resuscitation, post-operation is suitable for
postoperative progression. Complications: 41% (mainly pericardial
effusion, pleural effusion), other issues such as residual ventricular septal
defect: 13.7%, tricuspid valve regurgitation: 11%, pulmonary valve
regurgitation: 2.7% are acceptable. Pressure difference between right

ventricle - pulmonary artery: 22.7 mmHg through echocardiography when