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Cor Triatriatum
Definition
Classic (or typical) cor triatriatum, or cor triatriatum sinister, is a rare congenital cardiac anomaly in which the pulmonary veins typically enter a “proximal” left atrial chamber separated from the “distal” left atrial chamber by a partition in which there are one or more restrictive ostia. 1 In the Congenital Heart Surgery Nomenclature and Database Project, cor triatriatum is classified as a pulmonary venous anomaly, with subclassifications as described in Box 32-1 .
Box 32-1
From Herlong and colleagues.
Proposed Classification of Pulmonary Venous Anomalies
I. Primary Anomalies of Pulmonary Venous Connection
- A
Partially (or partial) anomalous pulmonary venous connection (or return or drainage) (PAPVC, PAPVR)
- 1
Non-scimitar
- 2
Scimitar (right pulmonary vein[s] draining to inferior vena cava)
- 1
- B
Totally (or total) anomalous pulmonary venous connection (or return or drainage) (TAPVC, TAPVC)
- 1
Supracardiac (supradiaphragmatic, type I)
- 2
Cardiac (supradiaphragmatic, type II)
- 3
Infracardiac (infradiaphragmatic, type III)
- 4
Mixed (type IV)
- 1
II. Atresia of the Common Pulmonary Vein
III. Cor Triatriatum (Stenosis of the Common Pulmonary Vein, Triatrial Heart, Cor Triatriatum Sinister)
- A
Accessory atrial chamber receives all pulmonary veins and communicates with left atrium
- 1
No other connections (classic cor triatriatum)
- 2
Other anomalous connections
- a
To right atrium directly
- b
With TAPVC
- a
- 1
- B
Accessory atrial chamber receives all pulmonary veins and does not communicate with left atrium
- 1
Anomalous connection to right atrium directly (cardiac TAPVC with all pulmonary veins first draining to a venous confluence)
- 2
With TAPVC (supracardiac or infracardiac TAPVC)
- 1
- C
Subtotal cor triatriatum
- 1
Accessory atrial chamber receives part of the pulmonary veins and connects to left atrium
- a
Remaining pulmonary veins connect normally
- b
Remaining pulmonary veins connect anomalously (partial cor triatriatum with PAPVC)
- a
- 2
Accessory atrial chamber receives part of the pulmonary veins and connects to right atrium
- a
Remaining pulmonary veins connect normally (PAPVC with anomalously connected pulmonary veins first draining to a venous confluence)
- b
Remaining pulmonary veins connect anomalously (mixed TAPVC)
- a
- 1
IV. Stenosis of Individual Pulmonary Veins
- A
Congenital
- B
Acquired
- 1
Postoperative
- 2
Other
- 1
Historical Note
1 Cor triatriatum dexter is a term used to describe the partially divided right atrium present in some cardiac malformations. This condition is considered in the chapter on tricuspid atresia (see Morphology in Chapter 41 ) and is unrelated to cor triatriatum sinister.
Cor triatriatum was apparently first described in 1868 by Church. The name cor triatriatum was applied to the malformation by Borst in 1905. The angiographic diagnosis seems first to have been made at Mayo Clinic and described by Miller and colleagues in 1964. Echocardiographic diagnosis of this cardiac anomaly was described by Ostman-Smith and colleagues in 1984 and by Wolf in 1986. The first surgical correction is believed to have been performed by Vineberg and Gialloreto in 1956; the second by Lewis and colleagues followed shortly thereafter.
Morphology
It is unfortunate that cor triatriatum was first defined as “an abnormal septum in the left auricle” and has been described as resulting in a “subdivided left atrium,” because these terms obscure surgically important concepts about cor triatriatum.
Morphology of Classic Cor Triatriatum
Typically, the proximal (common pulmonary venous) chamber is somewhat larger than the distal (left atrial) chamber. The common wall partitioning them (“diaphragm” or “membrane”), which may have one or more openings (apertures), is usually thick and fibromuscular ( Fig. 32-1 ). The aperture is typically two dimensional, meaning it has no length, but occasionally it is three dimensional, exhibiting a tubular or tunnel-like configuration.
The proximal chamber contains all pulmonary vein connections and is usually thick-walled, whereas the distal chamber always contains the left atrial appendage, leads into the mitral valve, and is thin-walled ( Fig. 32-2 ). Despite high pressure in the proximal chamber, the pulmonary veins are not dilated. Entry of the right pulmonary veins into the proximal chamber usually bears the same relationship to the right atrium and superior vena cava as in the normal heart ( Fig. 32-3 ).
The right ventricle is usually enlarged, but this enlargement depends on the presence and degree of left-to-right shunting at the atrial level. The left ventricle is usually normal in size or small. The fossa ovalis may be in the septum between the proximal chamber and right atrium, but occasionally it is in the septum between the distal chamber and right atrium. The foramen ovale is usually patent and stretched.
Relationship of Cor Triatriatum to Partial and Total Anomalous Pulmonary Venous Connection
In classic cor triatriatum, the right and left pulmonary veins can be considered as not joining the left atrium but rather as entering a chamber, generally posterior and a little superior or medial to the left atrium, that is analogous to the common pulmonary venous sinus found in many patients with total anomalous pulmonary venous connection (TAPVC; see Chapter 31 ). Indeed, Van Praagh and Corsini did not use the term proximal left atrial chamber, but called it the common pulmonary vein chamber of cor triatriatum . Marin-Garcia and colleagues used similar terminology.
From an embryologic standpoint, the confluence of the pulmonary veins is completely incorporated into the left atrium in a normal heart, is not incorporated into the left atrium in TAPVC, and is partially incorporated into the left atrium in cor triatriatum. Just as TAPVC does not always involve all pulmonary veins connecting to a single pulmonary venous sinus (i.e., mixed TAPVC), cor triatriatum does not always involve all pulmonary veins draining to the proximal chamber. There are several examples of cor triatriatum in which some of the pulmonary veins drain to the proximal chamber, and the remainder have classic anomalous drainage.
Partial anomalous left pulmonary venous connection (from left upper lobe only or from entire left lung) may connect to a left vertical vein that connects to the left brachiocephalic vein, with all other pulmonary veins entering the proximal chamber. Partial anomalous venous connection may consist of all left pulmonary veins connecting to the coronary sinus, with the proximal chamber receiving only the right pulmonary veins and connecting through the usual small orifice into the distal left atrial chamber. Comparisons to partial anomalous pulmonary venous connection (PAPVC) also exist. In these examples, some pulmonary veins connect to the proximal chamber, and the remainder connect normally to the left atrium.
In “partial” cor triatriatum, the right pulmonary veins alone may connect to the proximal chamber, with the left pulmonary veins connecting normally to the left atrium. Other unusual variants have been documented. The proximal chamber, receiving all pulmonary veins, may have an imperforate portion between it and a typical distal chamber and instead connect to the right atrium, whereas the right and left atria are in communication through a coronary sinus atrial septal defect, with the coronary sinus itself being completely unroofed (see Chapter 33 ). In another example, all pulmonary veins may fail to join an otherwise typical proximal chamber separated from the distal chamber by a perforated partition, and instead connect to a common pulmonary venous sinus behind the heart that may connect to the coronary sinus, superior vena cava, or infradiaphragmatically.
Relationship of Cor Triatriatum to a Left Superior Vena Cava
A left superior vena cava coexists with cor triatriatum considerably more frequently than with other types of congenital heart disease. One proposed pathogenesis of cor triatriatum is impingement of a left superior vena cava on the developing left atrium. Ascuitto and colleagues reported cases in which a persistent left superior vena cava joining a dilated coronary sinus impinged on the posterior wall of the left atrium and divided it into two chambers, both of which had defects that communicated with the right atrium. It seems clear that a relationship exists between these two anomalies, at least in some patients.
Associated Anomalies
In addition to PAPVC and unroofed coronary sinus with a left superior vena cava joining the left atrium, other associated anomalies include ventricular septal defect, coarctation of the aorta, atrioventricular septal defect, tetralogy of Fallot, and (rarely) asplenia and polysplenia.
Clinical Features and Diagnostic Criteria
Infants with classic cor triatriatum, with a small aperture between the proximal and distal chambers, usually present with evidence of low cardiac output, including pallor, tachypnea, poor peripheral pulses, and growth failure. When there is associated left-to-right shunting due to connection of the proximal chamber to the right atrium or because of associated PAPVC, evidence of pulmonary overcirculation and venous obstruction may be present in the chest radiograph, and right ventricular enlargement is prominent. In children and young adults, the classic presentation is with signs and symptoms of pulmonary venous hypertension. However, like mitral stenosis, cor triatriatum may present with less classic symptoms.
Diagnosis is usually made by echocardiography ( Fig. 32-4 ). Transesophageal echocardiography has also proven useful in selected cases. Recently, three-dimensional echocardiography has been used to identify complex morphology in cor triatriatum. Magnetic resonance imaging with three-dimensional reconstruction provides excellent delineation of both simple and complex morphology in cor triatriatum and is the imaging study of choice if standard two-dimensional echocardiography is not definitive. Cardiac catheterization and cineangiographic studies are no longer considered necessary unless major associated cardiac anomalies are suspected. However, further evidence may be obtained from selective cineangiographic studies and pressure measurements in the proximal and distal chambers. If the catheter cannot be manipulated into the proximal and distal chambers from the right atrium, sometimes an arterial catheter can be advanced into the left ventricle and retrogradely across the mitral valve and into the distal and then proximal chamber. Gradients of 20 to 25 mmHg have been demonstrated between the two chambers.
Natural History
Natural history depends on the effective size of the aperture in the partition between the proximal and distal chambers. When it is small, the infant becomes critically ill during the early months of life, with signs of pulmonary venous obstruction ( Fig. 32-5, A ). Without surgical treatment, such patients die at that young age. If the aperture is larger, the patient presents in childhood or young adulthood with the signs, symptoms, and prognosis of mitral stenosis.
In most patients, the aperture is severely restrictive, and approximately 75% of persons born with classic cor triatriatum die in infancy. However, when the proximal chamber communicates with the right atrium through a fossa ovalis atrial septal defect, the prognosis is better because the proximal chamber decompresses into the right atrium ( Fig. 32-5, B ). These patients present with signs of a large left-to-right shunt and generally survive longer than those with an obstructive aperture. Rarely, cor triatriatum may be discovered in an adult. Delay in diagnosis may be accounted for by a lesser degree of obstruction by the partition or by a unilateral pulmonary venous obstruction.
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