Cor triatriatum

 

Cor triatriatum: The utility of cardiovascular imaging

Amar Thakrar MD, Michael D Shapiro MD, Davinder S Jassal MD FRCPC, Tomas G Neilan MD, Mary Etta E King MD, Suhny Abbara MD

 

Cor triatriatum is a rare congenital heart defect characterized by a fibromuscular memberane dividing the left atrium into two chambers. Due to advances in cardiovascular imaging, there has been a rise in the diagnosis of cor triatrium, despite its rarity. The case of a 44 year old man in whom cor triatrium was discovered incidentally on 64-slice CT angiography and confirmed by echocais presented. The patient presented with worsening dyspnea on minimal exertion of the previous 5 months. CT angiography using a 64-slice multi-detector scanner was performed revealing minimal coronary artery disease. The left atrium was noted to be septated by a membrane into anterior and posterior chambers consistent with cor triatrium (Figure 1). Subsequent transthoracic echocardiography confirmed the diagnosis (Figure 2). Pulmonary function testing confirmed reactive airway disease as the etiology for the patient’s dyspnea. Discussion: Cor triatrium, first described by Church in 1868 (1) refers to a subdivision of the left atrium into proximal and distal chambers due to a fibromuscular membrane. The embryological basis for cor triatriatum is still a topic of debate. It is thought that the anomalous membrane may be the result of abnormal growth of the septum primum, or that it may be secondary to malincorporation of the embryonic common pulmonary vein into the left atrium. Another hypothesis postulates that persistence of a left-sided superior vena cava may impinge on the left atrium, resulting in the formation of an abnormal membrane (2,3,4). Demonstration of the membrane by two-dimensional imaging, evaluation of turbulent flow on colour Doppler and determination of any gradient across the membrane on continuous wave Doppler can be performed with echocardiography. In addition to echocardiography, cardiac CT is becoming an increasingly important cardiovascular imaging modality, especially in the noninvasive evaluation of coronary artery disease. At least two previous cases (5,6) of cor triatriatum have been diagnosed incidentally using CT. Our case is unique in that it is the first report of 64-slice multislice detector computed angiography revealing cor triatriatum. Summary: Our case illustrates a rare congenital anomaly diagnosed by noninvasive cardiac imaging. As improvements in spatial and temporal resolution continue, cardiac CT may become better suited to the dynamic imaging of anatomical defects in the heart, including, but not limited to, coronary artery disease. In addition to ischemic heart disease, valvular heart disease and cardiomyopathy, one should also consider congenital heart defects in the cardiac differential of any patient presenting with new-onset dyspnea on exertion.

 

Figures

Figure 1
A Oblique maximum intensity projection computed tomography image demonstrating the right upper pulmonary vein (RUPV) and the left lower pulmonary vein (LLPV) draining into the posterior chamber (PC), the incomplete atrial membrane, and the communication site between the PC and the anterior chamber (AC).
B Double oblique, paraseptal, long-axis view showing membrane in the left atrium, with the left upper pulmonary vein (LUPV) draining into the PC, the left atrial appendage (LAA) and the mitral valve within the AC. Ao Aorta; LCx Left circumflex artery; LV Left ventricle; RA Right atrium; RV Right ventricle
Figure 2
A Two-dimensional transthoracic echocardiographic apical four-chamber view demonstrating a membrane (aroow) in the left atrium (LA), consistent with cor triatriatum.
B Colour Doppler imaging in diastole reveals no evidence of turbulent flow across the membrane in the LA. Spectral Doppler confirmed the absence of a significant pressure gradient across the membrane (not shown). LV Left ventricle; RA Right atrium; RV Right ventricle

 

References:

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