When Both Great Arteries Arise From the Right Ventricle
Introduction
Congenital cardiac defects are often easiest to understand by asking:
Where do the great arteries arise?
Where is the VSD in relation to them?
And is pulmonary blood flow increased, reduced or obstructed?
Double Outlet Right Ventricle — DORV — is a particularly good example of why the name of a congenital defect does not always predict whether the baby will be pink or blue.
In DORV, both great arteries arise predominantly from the right ventricle. A Ventricular Septal Defect is almost always present and provides the principal route by which blood from the left ventricle can leave the heart. The physiology then depends heavily upon the position of that VSD and whether pulmonary outflow is obstructed. (Merck Manuals)
Body
What is Double Outlet Right Ventricle?
In normal anatomy:
Right ventricle → Pulmonary artery → Lungs
and
Left ventricle → Aorta → Body
In Double Outlet Right Ventricle, both the aorta and pulmonary artery arise predominantly from the right ventricle. (Merck Manuals)
This means the left ventricle has no normal direct outlet to a great artery.
Its blood must therefore pass through a Ventricular Septal Defect — VSD into the right ventricle before it can reach either the aorta or pulmonary artery.
The VSD is therefore not simply an associated hole.
It is effectively the left ventricular outlet.
Why the VSD Matters So Much
The most important anatomical question in DORV is:
Where is the VSD in relation to the aorta and pulmonary artery?
The four main relationships are:
- Subaortic
- Subpulmonary
- Doubly committed
- Remote or non-committed. (PubMed Central (PMC))
This relationship largely determines where left ventricular blood is directed and therefore what physiology the child develops.
Subaortic VSD
In a subaortic VSD, the defect lies closest to the aortic valve.
Left ventricular blood therefore has a relatively direct pathway:
Left ventricle → VSD → Aorta
If pulmonary outflow is unobstructed, the physiology may resemble a large conventional VSD.
A substantial amount of blood can flow from the left ventricle through the VSD into the right ventricle and then towards both great vessels.
Pulmonary blood flow may become excessive.
The child may therefore remain relatively pink but develop:
- tachypnoea;
- poor feeding;
- sweating during feeds;
- poor weight gain;
- and heart failure.
This is essentially a pulmonary over-circulation pattern. (Merck Manuals)
Subaortic VSD With Pulmonary Stenosis
Now add pulmonary outflow obstruction.
The physiology changes dramatically.
Blood entering the right ventricle has difficulty reaching the pulmonary artery.
More blood is therefore directed towards the aorta.
Because this includes deoxygenated right ventricular blood, systemic arterial saturation falls.
The physiology can resemble Tetralogy of Fallot:
VSD + pulmonary obstruction + right-to-left shunting → cyanosis.
The baby may therefore be markedly blue. (Merck Manuals)
This demonstrates a fundamental principle:
The same broad diagnosis — DORV — can produce either heart failure or cyanosis depending upon the anatomy.
Subpulmonary VSD
In a subpulmonary VSD, the defect lies beneath or closest to the pulmonary valve.
Left ventricular blood is therefore preferentially directed towards the pulmonary artery.
This arrangement produces a physiology similar to Transposition of the Great Arteries.
Oxygenated blood from the left ventricle tends to return towards the lungs.
Deoxygenated blood in the right ventricle is preferentially directed towards the aorta.
The two streams therefore become functionally separated in the wrong direction.
This variant is commonly associated with the term Taussig–Bing anomaly. (Merck Manuals)
Taussig–Bing Anomaly
In Taussig–Bing DORV:
Left ventricular blood → VSD → Pulmonary artery
while much of the right ventricular blood exits through the aorta.
This produces a transposition-like circulation and may result in significant cyanosis.
Because pulmonary blood flow may also be high, these infants can simultaneously develop pulmonary over-circulation and heart failure.
This is another example of why congenital physiology cannot always be reduced to “blue” or “pink” alone.
Doubly Committed VSD
In a doubly committed VSD, the defect lies close to both the aortic and pulmonary valves.
Left ventricular blood therefore has relatively direct access to both great vessels. (PubMed Central (PMC))
The exact physiology depends upon:
- relative resistance of the two outflow tracts;
- any pulmonary stenosis;
- the spatial relationship of the vessels;
- and the size of the VSD.
From a surgical perspective, the relationship can sometimes make a two-ventricle repair comparatively favourable.
Remote or Non-Committed VSD
In a remote or non-committed VSD, the defect is located some distance from both great arteries.
This can make surgical reconstruction much more difficult.
The surgeon may have no straightforward route for creating an internal tunnel from the left ventricle to the aorta.
The feasibility of biventricular repair therefore depends upon detailed three-dimensional anatomy. (PubMed Central (PMC))
In some patients, a functionally single-ventricle pathway may ultimately be required.
Why Can DORV Produce Such Different Physiology?
The answer is streaming.
Blood entering the right ventricle does not simply mix completely and randomly.
Its direction is influenced by:
- VSD position;
- the geometry of the ventricular cavity;
- relationship of the great arteries;
- outflow resistance;
- and pressure gradients.
If left ventricular blood is directed predominantly towards the aorta, systemic oxygenation may be relatively good.
If it is directed predominantly towards the pulmonary artery, the physiology can resemble TGA.
If pulmonary flow is unobstructed and excessive, the child may develop heart failure.
If pulmonary flow is obstructed, cyanosis may dominate.
The key question is therefore not simply:
“Does the child have DORV?”
but:
“Where is the VSD and where is the blood actually going?”
Position of the Great Arteries
The spatial relationship between the aorta and pulmonary artery also varies in DORV.
They may lie:
- side-by-side;
- with the aorta anterior and rightward;
- with the aorta anterior and leftward;
- or in other unusual relationships.
This has major implications for surgical planning.
Cross-sectional imaging can therefore be particularly valuable when the anatomy is complex. (Merck Manuals)
Associated Pulmonary Stenosis
Pulmonary stenosis is one of the most important modifiers of DORV physiology.
If severe, pulmonary blood flow falls.
The child becomes more cyanosed.
In the most severe cases, pulmonary blood flow may become duct-dependent and Prostaglandin E1 may be required to maintain ductal patency in the neonatal period. (Merck Manuals)
If pulmonary obstruction is absent, excessive pulmonary blood flow may instead dominate.
Again:
too little pulmonary blood flow → cyanosis
too much pulmonary blood flow → heart failure
Associated Aortic Obstruction
DORV can also occur with:
- coarctation of the aorta;
- hypoplastic aortic arch;
- or Interrupted Aortic Arch.
These associated lesions can profoundly alter systemic perfusion.
This is particularly important in Taussig–Bing anatomy, where arch obstruction is well recognised.
The entire systemic outflow therefore has to be assessed, not merely the ventricular connections.
Clinical Presentation
Because DORV describes a broad anatomical spectrum, presentation varies considerably.
A child may present with:
Pulmonary over-circulation
- tachypnoea;
- sweating during feeds;
- poor weight gain;
- recurrent respiratory symptoms;
- hepatomegaly;
- and heart failure.
Reduced pulmonary blood flow
- cyanosis;
- reduced oxygen saturation;
- hypercyanotic episodes;
- or duct-dependent pulmonary circulation.
Transposition-like physiology
- profound neonatal cyanosis;
- pulmonary over-circulation;
- and dependence upon adequate mixing.
The clinical picture is therefore determined by the anatomy rather than by the diagnostic title alone. (Merck Manuals)
Diagnosis
Echocardiography
Echocardiography is central to diagnosis.
The important questions include:
- Do both great arteries arise predominantly from the right ventricle?
- Where is the VSD?
- How large is it?
- Which great artery is closest to it?
- Is pulmonary stenosis present?
- Is systemic outflow obstructed?
- What is the ventricular size and function?
- Are there associated AV valve abnormalities?
- What is the relationship of the great arteries?
These details determine the surgical strategy.
CT and MRI
CT and MRI can provide detailed three-dimensional information about:
- VSD-to-great-artery relationships;
- coronary anatomy;
- pulmonary arteries;
- aortic arch anatomy;
- ventricular volumes;
- and complex spatial relationships.
Modern three-dimensional imaging is particularly useful in DORV because surgical repair is fundamentally an exercise in rerouting blood through complex three-dimensional anatomy. (PubMed Central (PMC))
Cardiac Catheterisation
Cardiac catheterisation may be used when additional haemodynamic information is required.
It can provide information about:
- pulmonary artery pressure;
- pulmonary vascular resistance;
- pressure gradients;
- oxygen saturations;
- and associated vascular anatomy. (Merck Manuals)
It is no longer necessary for every patient purely to establish the diagnosis.
Surgical Treatment
There is no single “DORV operation.”
The operation is chosen according to the anatomy.
The principal objective, whenever possible, is to establish:
Left ventricle → Aorta
and
Right ventricle → Pulmonary artery
How this is achieved varies enormously.
Intraventricular Tunnel Repair
In many patients with a subaortic VSD, an internal patch or baffle can be used to direct blood from the left ventricle through the VSD to the aorta.
Thus:
Left ventricle → VSD → Intracardiac tunnel → Aorta
The remaining right ventricular cavity then supplies the pulmonary artery.
This is one of the most straightforward forms of biventricular DORV repair. (Merck Manuals)
Relief of Pulmonary Obstruction
If pulmonary stenosis is also present, it must be addressed.
This may involve:
- muscle resection;
- enlargement of the RV outflow tract;
- pulmonary valvotomy;
- transannular patching;
- or placement of an RV-to-PA conduit.
The principle is similar to repair of Tetralogy of Fallot.
The Rastelli Procedure
Some forms of DORV with pulmonary outflow obstruction are suitable for a Rastelli-type repair.
The operation uses an intracardiac tunnel to direct left ventricular blood through the VSD to the aorta.
A valved conduit then connects the right ventricle to the pulmonary artery.
Thus:
Left ventricle → VSD → Aorta
and
Right ventricle → Conduit → Pulmonary artery
The conduit does not grow with the child and may therefore require future replacement.
Taussig–Bing Repair
Taussig–Bing anatomy behaves much more like TGA.
The VSD directs left ventricular blood towards the pulmonary artery rather than the aorta.
Simply closing the VSD to the nearest vessel would therefore leave the left ventricle connected functionally to the pulmonary circulation.
Modern repair often involves:
VSD closure/tunnelling + arterial switch operation. (Merck Manuals)
The great arteries are repositioned so that the left ventricle ultimately supplies the systemic circulation.
This demonstrates again why DORV cannot be described by one surgical technique.
Remote VSD and Complex DORV
When the VSD is remote from both great arteries, constructing a long internal tunnel may:
- obstruct ventricular inflow;
- obstruct the right ventricular outflow tract;
- compromise ventricular volume;
- or create an excessively complex pathway.
Some patients may still be suitable for specialised biventricular repair.
Others may require staged palliation towards a Fontan circulation. (Merck Manuals)
The decision depends upon:
- ventricular size;
- VSD location;
- AV valve anatomy;
- great artery relationship;
- and associated obstructions.
One-and-a-Half or Single-Ventricle Strategies
Not every DORV heart can safely be converted into two independent ventricular circulations.
When ventricular anatomy is severely unbalanced or intracardiac routing is impossible, staged single-ventricle palliation may be considered.
This can ultimately involve:
Glenn → Fontan
rather than anatomical biventricular correction.
Again, the defect is being managed according to physiology and anatomy, not simply according to its name.
Cardiopulmonary Bypass
Most definitive DORV repairs require cardiopulmonary bypass.
The surgeon may need to:
- enlarge or reroute the VSD;
- construct a complex intracardiac baffle;
- repair pulmonary stenosis;
- perform an arterial switch;
- insert a conduit;
- reconstruct the arch;
- or combine several of these procedures.
For the theatre team, understanding the planned route of left ventricular blood is particularly useful.
The central surgical question is:
How are we getting blood from the left ventricle to the aorta?
Anaesthetic and Theatre Considerations
Because DORV physiology varies so widely, anaesthetic management has to be tailored to the individual anatomy.
The patient may have:
- excessive pulmonary blood flow;
- severely restricted pulmonary blood flow;
- systemic outflow obstruction;
- transposition-like physiology;
- or single-ventricle physiology.
Therefore, the effect of changing:
- PVR;
- SVR;
- preload;
- ventilation;
- and oxygen concentration
depends upon the specific lesion.
A strategy appropriate for one form of DORV may be harmful in another.
This makes accurate preoperative anatomical and physiological understanding essential.
After Repair
Postoperative management depends heavily upon the repair performed.
Important potential issues include:
- residual VSD;
- obstruction within an intracardiac tunnel;
- LV outflow tract obstruction;
- RV outflow tract obstruction;
- conduit dysfunction;
- pulmonary artery stenosis;
- coronary complications after arterial switch;
- ventricular dysfunction;
- AV valve regurgitation;
- and arrhythmias.
The repair may need to be reassessed repeatedly as the child grows.
Long-Term Follow-Up
DORV is classified among the more complex congenital cardiac abnormalities, and patients require lifelong congenital cardiology surveillance. (professional.heart.org)
Long-term problems may include:
- recurrent outflow obstruction;
- conduit degeneration;
- valve disease;
- ventricular dysfunction;
- arrhythmias;
- aortic root problems;
- and need for further catheter or surgical intervention.
The exact follow-up pathway depends heavily upon the original anatomy and type of repair.
DORV in One Sentence
Double Outlet Right Ventricle is a congenital abnormality in which both great arteries arise predominantly from the right ventricle, leaving the VSD as the principal outlet from the left ventricle.
The two most important questions are:
Where is the VSD?
and
Is pulmonary blood flow obstructed?
Those two answers explain much of the child’s physiology.
Key Points
Both the aorta and pulmonary artery arise predominantly from the right ventricle. (Merck Manuals)
A VSD is almost always present and provides the main exit route from the left ventricle. (Merck Manuals)
The principal VSD relationships are:
Subaortic
Subpulmonary
Doubly committed
Remote/non-committed. (PubMed Central (PMC))
A subaortic VSD without pulmonary stenosis can resemble a large VSD and produce pulmonary over-circulation and heart failure.
A subaortic VSD with pulmonary stenosis can resemble Tetralogy of Fallot and produce cyanosis.
A subpulmonary VSD can produce TGA-like physiology and is associated with Taussig–Bing anomaly. (Merck Manuals)
There is no single DORV operation.
Surgical treatment may include:
- intracardiac tunnelling;
- relief of pulmonary stenosis;
- Rastelli-type repair;
- arterial switch;
- conduit placement;
- or single-ventricle palliation.
The anatomy determines the operation.
Glossary of Terms
Arterial Switch Operation — ASO
An operation in which the great arteries are transferred to their appropriate ventricular outflows.
It can form part of the repair of Taussig–Bing DORV.
Biventricular Repair
A surgical strategy that retains both ventricles as functional pumping chambers, with one supporting the systemic and the other the pulmonary circulation.
Cardiopulmonary Bypass — CPB
A technique in which a heart-lung machine temporarily maintains circulation and gas exchange during cardiac surgery.
Conduit
A surgically implanted tube connecting two cardiovascular structures.
An RV-to-PA conduit may be used in some DORV repairs.
Cyanosis
Bluish discoloration caused by increased deoxygenated haemoglobin in systemic arterial blood.
Double Outlet Right Ventricle — DORV
A congenital abnormality in which both great arteries arise predominantly from the right ventricle.
Doubly Committed VSD
A VSD located close to both the aortic and pulmonary valves.
Fontan Circulation
A single-ventricle circulation in which systemic venous blood flows directly to the pulmonary arteries without being pumped by a subpulmonary ventricle.
Intracardiac Baffle
A surgically constructed internal pathway used to redirect blood within the heart.
In DORV, it may direct left ventricular blood through the VSD towards the aorta.
Left Ventricular Outflow Tract — LVOT
The pathway through which blood leaves the left ventricle towards the systemic circulation.
Non-Committed VSD
A VSD located remotely from both great arteries.
Also called a remote VSD.
Pulmonary Over-Circulation
Excessive blood flow through the lungs.
It may occur in DORV when pulmonary outflow is unobstructed.
Pulmonary Stenosis
Narrowing of the right ventricular outflow tract, pulmonary valve or pulmonary arterial pathway.
Its presence can convert DORV physiology from predominantly pulmonary over-circulation to cyanotic physiology.
Pulmonary Vascular Resistance — PVR
Resistance to blood flow through the pulmonary circulation.
Rastelli Procedure
A repair in which left ventricular blood is directed through the VSD to the aorta and a conduit connects the right ventricle to the pulmonary artery.
Remote VSD
See Non-Committed VSD.
Right Ventricular Outflow Tract — RVOT
The pathway carrying blood from the right ventricle towards the pulmonary artery.
Streaming
Preferential direction of blood flow through the heart according to anatomy and pressure gradients rather than complete mixing.
Streaming is particularly important in understanding DORV physiology.
Subaortic VSD
A VSD located closest to the aortic valve.
It often allows relatively direct routing of left ventricular blood to the aorta.
Subpulmonary VSD
A VSD located closest to the pulmonary valve.
This can produce TGA-like physiology.
Systemic Vascular Resistance — SVR
Resistance to blood flow through the systemic circulation.
Taussig–Bing Anomaly
A form of DORV characterised principally by a subpulmonary VSD and transposition-like physiology.
Ventricular Septal Defect — VSD
An abnormal communication between the ventricles.
In DORV, the VSD is critically important because it usually provides the only effective outlet from the left ventricle.
