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Total Anomalous Pulmonary Venous Connection And Cor Triatriatum

Total Anomalous Pulmonary Venous Connection and Cor Triatriatum

1. Embryology

A. Total anomalous pulmonary venous connection (TAPVC) develops when the primordial pulmonary vein fails to unite with the plexus of veins surrounding the lung buds. This results in return of pulmonary venous blood to the heart via a systemic vein, and subsequently to the right atrium.

2. TAPVC Classification

A. TAPVC is classified according to the site of connection
B. Supracardiac includes connections to the left innominate vein, the SVC, or the azygous
C. Cardiac includes connections to the coronary sinus or directly to the right atrium
D. Infracardiac includes connections below the diaphragm to the IVC, the portal vein, hepatic veins, or ductus venosus
E. Mixed type involves connections of two or more of these types; at least one of the main lobar pulmonary veins is draining differently from the others
TypeIncidence
Supracardiac50%
LSVC40%
RSVC10%
Cardiac25%
Coronary sinus20%
Right atrium5%
Infracardiac20%
Mixed5%

3. Anatomic Factors

A. Left atrium is reduced 50% in size due to absence of common pulmonary vein component
B. Left ventricle is normal in function and mass; the cavity may be small
C. PFO or secundum ASD is always present; these are usually non-restrictive
D. Varying degrees of pulmonary venous obstruction and congestion are present and occur most commonly in the infracardiac type

4. Pathophysiology

A. All pulmonary venous blood returns to the right atrium
B. Intracardiac systemic and pulmonary venous mixing occurs
C. A right-to-left shunt at the atrial level (PFO, ASD) must be present for survival
D. Increased pulmonary blood flow and pulmonary venous obstruction will eventually result in pulmonary hypertension

5. Diagnosis

A. Clinical features are determined by the degree of pulmonary venous obstruction
B. If obstruction is severe, infant will be critically ill
C. Tachypnea, hypoxemia, and metabolic acidosis
D. Cyanosis can be unimpressive or severe
E. Chest Xray shows ground glass (diffuse alveolar pattern) or "snowman" appearance from persistent vertical vein
F. Echocardiography useful to trace connections of all pulmonary veins and look for free space behind the left atrium
G. Catheterization delineates the exact anatommy, evaluates degree of pulmonary venous obstruction and hypertension, and identifies other structural abnormalities

6. Management

A. Patients with TAPVC should undergo operative repair when the diagnosis is made
B. Obstructed TAPVC is a surgical emergency
C. Non-obstructed TAPVC should have prompt repair as well, as the clinical status of these patients can deteriorate rapidly
D. Early repair of non-obstructed TAPVC also prevents the adverse sequelae of cyanosis and volume overload of the heart and lungs

7. Operative Technique

A. Cardiopulmonary bypass with hypothermic circulatory arrest is the preferred approach in critically ill infants
B. Surgical goals are eliminating all anomalous connections, draining the pulmonary veins into the left atrium, and closing intracardiac shunts
C. The PV-LA anastomosis must be large and undistorted
D. Supracardiac Type
1) Left SVC connection
a) Ligate left-sided vertical vein at junction with innominate vein
b) Open left atrium and incise the posterior wall
c) Find and incise the anterior wall of the confluence
d) Anastomose the pulmonary venous confluence to the left atrium
e) Close PFO or ASD through left atrium or through separate right atrial incision
2) Right SVC connection
a) Expose pulmonary venous confluence and anastomose to left atrium as above
b) Ligate anomalous connections or patch from within SVC
c) A baffle may be used instead to channel flow from the right SVC through an enlarged interatrial connection
3) Azygous connection
a) Ligate anomalous connection
b) Anastomose confluence to left atrium as above
E. Cardiac Type
1) Coronary sinus connection
a) Create common large interatrial connection by incising coronary sinus septum and septum primum
b) Close this new defect with a single patch; all pulmonary venous return and coronary sinus return now drains into the left atrium
2) Right atrium connection
a) Enlarge interatrial connection
b) Create baffle to direct flow from pulmonary venous opening across interatrial connection
F. Infracardiac Type
1) Ligate PDA once CPB is established
2) Identify and ligate anomalous descending vertical vein at the diaphragm
3) Initiate circulatory arrest
4) Open left atrium and incise the posterior wall
5) Find and incise the anterior wall of the confluence
6) Anastomose the pulmonary venous confluence to the left atrium
7) Close the interatrial communication

8. Results

A. Early (hospital) mortality ranges from 2-20%
B. 90% of patients are cured
C. 5-10% have late failure of repair due to pulmonary venous obstruction

9. Risk Factors

A. Poor pre-operative status (acidosis)
B. Pulmonary venous obstruction
C. High pulmonary vascular resistance
D. Young age
E. Small left ventricle
F. Major associated anomalies
G. Infracardiac or mixed type (see below)

10. Problems with Mixed Type

A. No pulmonary venous confluence
B. Requires 2 or more anastomoses
C. Smaller anastomoses predispose to pulmonary venous obstruction
D. Risk of mortality and late pulmonary venous obstruction is increased
E. Operative repair probably not curative

COR TRIATRIATUM

1. Morphology

A. Pulmonary veins enter proximal LA chamber and are separated from distal LA chamber by a diaphragm
B. A small hole in this diaphragm allows some communication to the distal chamber
C. The RV is enlarged
D. The fossa ovalis is patent, which allows left-to-right shunting
E. This interatrial connection usually communicates the proximal chamber to the RA and occasionally the distal chamber to the RA
F. The distal chamber contains the mitral valve and left atrial appendage

2. Clinical Features

A. Patients present in infancy with pulmonary venous hypertension
B. Low cardiac output, pallor, tachypnea, and growth failure are characteristic
C. Severity of symptoms depends on the size of the hole in the diaphragm
D. The PFO/ASD may decompress the pulmonary veins into the RA
E. If the ASD is above the diaphragm, there will be a large shunt
F. If the ASD is below the diaphragm, the clinical picture is similar to mitral stenosis

3. Operative Technique

A. Left atrial approach
1) Better if the patient is older and larger
2) Excise-A the obstructing diaphragm
3) Enlarge the left atrium as needed and close the interatrial connection
B. Right atrial approach
1) Better if the patient is younger and smaller
2) Locate the diaphragm through the ASD
3) Excise-B the obstructing diaphragm
4) Close the ASD

4. Results

A. Early (hospital) death is uncommon
B. Pulmonary vein stenosis or restenosis of the orifice are also uncommon late events