A rare congenital heart defect, cor triatriatum, can demonstrate variability with regard to (1) location and orientation of the obstructing membrane; (2) relative position and size of atrial septal defects (ASD); and (3) pulmonary venous connection. A classification system proposed by Lucas and Krabill incorporates these variables and includes cases of "subtotal" cor triatriatum wherein only a portion of the pulmonary venous return connects to the accessory chamber. In these cases, the remainder of the pulmonary venous return may connect to the left atrium directly or to the right atrium, either directly or indirectly. The usual anatomic arrangement ("classic cor triatriatum") results in a posterosuperior accessory chamber receiving the pulmonary veins and an anteroinferior chamber which communicates with the left atrial appendage and pulmonary mitral valve. If present, an ASD can communicate with either chamber.
Imaging in Cor Triatriatum
Transthoracic echocardiographic Doppler techniques may provide high quality images. Diagnostic hemodynamic assessment can be refined with standard color flow, pulsed, and continuous wave Doppler techniques. In children (where the lesion usually presents), Doppler transthoracic echocardiography is usually diagnostic. Detailed images may be more difficult to obtain in older children and adults. A combination of parasternal long axis, apical four-chamber, and subxiphoid four-chamber views will allow visualization of the membrane and characterization of any resultant flow disturbance. Angiographic detection of the membrane is possible using pulmonary arteriography or direct left atrial injection contrast material. The membrane will appear as a lucency within the left atrium. Detailed information concerning the orientation of the membrane and its attachments may be difficult to obtain, particularly in older children and adults.
Transesophageal echocardiography places the imaging apparatus adjacent to the left atrium, and biplane transesophageal echocardiography provides an enhanced capability for complete and detailed visualization of the left atrial cavity, left atrial appendage, pulmonary veins, and vividly depicts the atrial septum as seen in the excellent images in the review by Seward and colleagues. The ability to obtain high resolution detailed images of the left atrium and of the atrial septum has resulted in application of single and multiplane transesophageal echocardiography to a multitude of clinical problems, including  precise definition of atrial sinus based on morphology of atrial appendages; (2) assessment of anomalies of the atrioventricular junction; (3) intraoperative assessment of atrioventricular septal defect; (4) postoperative assessment of intra-atrial baffles; (5) endocarditis; and (6) hemodynamic assessment of atrial pressure dynamics based on atrial septal configuration throughout the cardiac cycle, to name a few. The safety of the technique has been documented in adults and children.[12,13]
Multiplanar images coupled with computer-assisted dynamic special reconstruction, as reviewed by Belohlavek and colleagues, create almost fantastic images. The transesophageal approach provides high quality images which appear to be well suited to spatial reconstruction techniques.
In this issue of Chest (see page 601), Kacenelenbogen and Decoodt review a case in which biplane transesophageal echocardiography confirmed the presence of a left atrial membrane in what appears to be a partial cor triatriatum. Doppler data provided complete hemodynamic characterization of the severity of the lesion. In this case, the data demonstrated the lesion to be sufficiently mild to forgo any surgical therapy. The case illustrates the role for biplane technology in that imaging in the longitudinal plane provided a more complete anatomic and hemodynamic picture.
While the role of biplane technology appears to be obvious with regard to imaging capability, the clinical role of transesophageal echocardiography in general in cases such as these is unclear, particularly in the setting of a normal physical exam, ECG, and x-ray film. The case in larger context, however, illustrates that transesophageal echocardiography may be able to obtain information not completely obtained by transthoracic study, thereby avoiding the need for catheterization in some cases. Clearly, the Doppler velocities confirmed the absence of hemodynamically important left ventricular inflow obstruction and gave good support to a decision against further workup or surgery.
The capabilities of transesophageal echocardiography and now multiplanar transesophageal echocardiography are increasingly being recognized and applied. Three-dimensional image reconstruction and "virtual reality" may provide the clinician with more detailed anatomic images than ever before. The images provided by transesophageal echocardiography will no doubt make this technique an important research and clinical tool for some time to come. These techniques have evolved considerably in a relatively short period, and as yet, there is no standardized terminology analogous to that previously adopted for two-dimensional echocardiography. A standardized terminology will promote uniformity of image display which will enhance communication between diagnostic and treatment centers, as well as teaching and research.
 Lucas RV Jr, Krabill KA. Anomalous venous connections, pulmonary and systemic. In: Adams FH, Emmanouilides GC, Riemenschneider TA, eds. Moss's heart disease in infants, children, and adolescents. Baltimore: Williams & Wilkins, 1989; 580-627
 Niwayama G. Cor triatriatum. Am Heart J 1960; 59:219-317
 Snider AR, Serwer GA. Abnormalities of left ventricular inflow. In: Echocardiography in pediatric heart disease. Chicago: Yearbook Medical Publishers, 1990; 221-30
 Freedom RM, Culham JAG, Moes CAF. Abnormalities of pulmonary venous connections and obstruction to pulmonary venous flow. In: Angiocardiography of congenital heart disease. New York: Macmillan Publishing Co, 1984; 274-302
 Seward JB, Khandheria BR, Edwards WD, Oh JK, Freeman WK, Tajik AJ. Biplanar transesophageal echocardiography: anatomic correlations, image orientation, and clinical applications. Mayo Clin Proc 1990; 65:1193-1213
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 Kaulitz R, Stumper OFW, Geuskens R, Sreeram N, Elzenga NJ, Chan CK, et al. Comparative values of the precordial and transesophageal approaches in the echocardiographic evaluation of atrial baffle function after an atrial correction procedure. J Am Coll Cardiol 1990; 16:686-94
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 Kusumoto FM, Muhiudeen IA, Kuecherer HF, Cahalan MK, Schiller NB. Response of the interatrial septum to transatrial pressure gradients and its potential for predicting pulmonary capillary wedge pressure; an intraoperative study using transesophageal echocardiography in patients during mechanical ventilation. J Am Coll Cardiol 1993; 21:721-28
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 Belohlavek M, Foley DA, Gerber TC, Kinter TM, Greenleaf JF, Seward JB. Three and four dimensional ultrasound imaging: a new era for echocardiography. Mayo Clin Proc 1993; 68:221-40
 Silberbach M, Sahn DJ. Three dimensional echocardiography reconstruction: from "ice-pick" view to virtual reality. Mayo Clin Proc 1993; 68:311-12
 Henry WL, DeMaria A, Gromiak R, King DL, Kisslo JA, Popp RLM, et al. Report of the American Society of Echocardiography Committee on nomenclature and standards in two-dimensional echocardiography. Circulation 1980; 62:212-17
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