正常人右心室出口是肺動脈 左心室出口是主動脈
在人類胚胎發育心臟過程中 會經歷兩根大血管(主動脈 肺動脈) 根部Conus的發育
在主動脈根部下方的conus若沒有在發育過程中適當的消失 造成主動脈被擠壓到右心室
就會造成右心室同時發出兩根大血管 肺靜脈血流進入左心室 仍需要出口
所以一定會出現一個心室中膈缺損(VSD) 才能將血液導引到肺循環或體循環
若此VSD導引的血流大多流向肺動脈 稱為 subpulmonic VSD ; 反之，若多導引到主動脈
則稱為 subaortic VSD。若導引到主動脈與肺動脈血流一樣多，稱為 doubly-comitted VSD,
若此心室中膈缺損離兩根大血管都有一段距離，則稱為 non-comitted VSD.
以下重點整理與圖表均出自 Moss & Adams' Heart Disease in infants, Children, and Adolescents: Including the Fetus and Young Adult 10/E 2022 第49章 DORV
1.
心臟在旋轉時發育出conus, conotruncal defect 是旋轉過程中產生的缺陷
2.
Conus 在發育過程中促進心臟的旋轉
3.
Conus 通常在PV的正下方 把PA往前往上推
4.
Truncus 在發育的時候 Ao的conus被吸收掉所以落到PA後下方
5.
DORV時 AO的conus沒有被吸收 所以被往前推 造成RV同時出AO跟PA
6.
AV，ＴＶ，ＭＶ同時連接在心臟中央的fibrous body
7.
TOF type, Ao 下面有 conus, PA下面有conus -> 無AV-MV continuity
TGA type, Ao 下面有 conus, PA下面無conus -> 無PV-MV continuity
9.
Conus 在發育與退化過程中
造成大血管位置關係的改變 形成DORV 而不是VSD本身
10.
VSD 位置 subaortic, subpulmonic, doubly-comitted, remote VSD, VSD為LV的唯一出口
11.
VSD 位置通常在 outlet septum between the anterior and posterior limbs of the
septomarginal trabeculation
12.
Conal Septum tissue 越多 VSD 離它距離越遠
13.
DORV需要描述 Outlet Septum與VSD的關係 在左側或右側 通常與VSD垂直
14.
DORV有50%合併PS, 25% Secundum ASD, 10% CA anomaly (AD from RCA)
15.
若PS造成cyanosis 可在兩個月到四個月大時
做palliative shunt 例如BT shunt
16.
用buffle將LV的血流導引到Ao
課本分為五大常見DORV類型: TOF, TGA, VSD, doubly committed,
non-comitted type
TOF type (40%) : DORV with subaortic VSD with PS PV
conal septum anterior malalignment pull AV to override the IVS SpO2: 80-90%
PE: LUSB harsh systolic "PS"
murmur , no additional PS murmur
EKG: RAD, RVH
Echo: absence of mitral-aortic continuity,
chordal attachments of each AV valve and their relationships to the VSD
描述: PV下面的conus往前往上擠 造成PS Ao下面有一個subaortic VSD,
outlet septum 在VSD左側 與VSD垂直
TGA type (20%): “Taussig–Bing anomaly” or “DORV with subpulmonic
VSD
Conus 在 AO下方把AO往PA的右前方推 PV下面幾乎沒有Conus PV, MV 無 continuity
Subpulmonic
VSD 把LV血流導引到PA RV的缺氧血進到AO 所以 PA的氧分壓高於AO
此類病人出生後血氧與TGA類似 取決於ASD與PDA血流的多寡與mixing的程度
Echo:
subcostal view 要看清楚
subaortic conus的長度 是否有AS, 會影響到Arch的發育
TV
attach to subaortic conal septum
PV
override the IVS cause subpulmonic VSD
手術要將LV與AO重新連接
VSD type (15%) : DORV with subaortic VSD without PS
PV下面的conus比AV下面的conus多 AV下面的conus把Ao往PA的右邊推 PA還是在前方
Bilateral
conus, AV下面的conus 造成 AV MV lose continuity
病生理學:
large VSD with significant left-to-right shunting and pulmonary overcirculation
臨床表現: Infants typically present with signs of congestive heart failure
as the pulmonary vascular resistance falls between 4 and 8 weeks of age
DORV with doubly-committed VSD (<10%)
型態: Both great vessels override the crest of the ventricular septum.
The VSD is in the usual position, cradled between the limbs of the
septomarginal trabeculation
病生理學: The pathophysiology is predominantly left-to-right shunting with
pulmonary overcirculation unless there is valvar PS.
治療: Surgical VSD closure directs flow from the left ventricle to the
posterior and rightward aorta
超音波型態如下
DORV with Noncommitted VSD (<10%)
Significant
amount of conus beneath each great vessel such that neither vessel is truly
posterior
Typically-positioned
VSD opens primarily into the body of the RV
May be
some degree of subvalvar and valvar PS resulting in either balanced
circulations or inadequate pulmonary blood flow
Complete
repair in early infancy is seldom technically feasible
Palliative
aortopulmonary shunt may be required
Echo: define the relationships of the great
vessels, the relative position of the VSD to the great vessels, the anatomy of
the subvalvar regions and the semilunar valves, and the adequacy of both
ventricles
其他更少見的型態: DORV occurs with mitral atresia and
with AV canal defects in the constellation of heterotaxy syndrome. DORV is also noted with AV discordance. (Moss Ch50,
Ch51)
Surgical decision-making
1. The distance between the tricuspid valve and the
pulmonary valve should be large enough to employ a
left ventricle-to-aorta baffle repair. If papillary muscle tissue is located in
the pathway from the LV to aorta, relocation of the papillary muscle or valve
replacement may need to be considered.
2. How much the baffle could encroach on
the right ventricular volume : when
decide to perform BVR
3. Exact course of the coronary arteries
4. Biventricular repair is performed if it
is feasible
5. Adequate left ventricular outflow tract must be
created, even if it compromises the right ventricular
outflow (the right ventricular outflow tract can be reconstructed by
infundibulectomy, valvotomy, gusset, or conduit)
6. Physiologic correction:
VSD:
eliminate L -> R shunt
TOF:
routing LV to Ao, enlarge RVOT
TGA:
OT switch to achieve two-ventricle physiology
Stepwise decision making
1. Sizes of the ventricles and AV valves
should be measured
2. IF BVR, whether left ventricle-to-aortic
baffle can be created without creating any LV outflow tract
obstruction?
3. TGA type DORV: Patrick-McGoohan
procedure (if great vessel relationships are anterior–posterior or l-
position with a large VSD) ; Kawashima
procedure (Taussig–Bing anatomy with a large distance between
the tricuspid valve and the pulmonary
valve)
4. When a left ventricle-to-aortic baffle
cannot be created, but a left ventricle-to-pulmonary valve pathway
can be constructed without any
stenosis, an arterial switch operation can be performed.
5. If stenosis between RV to PA, Rastelli
conduit or REV procedure is added to arterial switch
6. If LV to AV or LV to PV pathway could
not be achieved without stenosis, DKS with with RV-PA conduit
(Yasui
procedure) for BVR could be performed
7. Extending biventricular repair to
borderline anatomic candidates who had hypoplastic left-sided
structures or a nonsubaortic VSD is a
questionable strategy.
8. DORV s/p BVR : Late reoperation and late
mortality were significantly higher in the patients with a
noncommitted VSD.
9. Patients who undergo a Rastelli-type
repair require one or more right ventricle-to-pulmonary artery
conduit replacements
10. Patients with a complex intracardiac
baffle are at substantial risk of LVOTO (high risk in subpulmonic
VSD)
11. TGA type DORV outcome was similar to
simple d-TGA (neo AR is more common than d-TGA)
Right
bundle branch block and QRS prolongation after repair are common and may
suggest an
increased risk of sustained
ventricular tachycardia and sudden cardiac death
DORV病人在成人期可能會出現的併發症
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