Central shunt (ascending aorta to pulmonary artery) is a palliative procedure performed in patients with cyanotic heart disease. The assessment of congenital aorto-pulmonary communications by transthoracic echocardiography (TTE) may be suboptimal, particularly postoperatively, due to limited acoustic windows. Reports describing transesophageal echocardiography (TEE) assessment of aorto-pulmonary shunts are limited, , but have shown that the imaging is superior to that of TTE.  The imaging may be difficult due to the fact that ascending aorta is an anterior structure (farther from the TEE probe) and also the interposed carina may interfere with the imaging. We present a patient in whom the central shunt could be visualized clearly (both 2D and color flow) on TEE examination and describe its features.
A 12-year-old girl, weighing 29 kg, presented with the chief complaint of dyspnea (New York Heart Association grade III). Physical examination revealed cyanosis, clubbing, single second heart sound, and a pansystolic murmur over the lower-left sternal border. She was a follow-up case of cyanotic congenital heart disease, pulmonary atresia with ventricular septal defect (VSD) and had undergone surgery for 5 mm central Gore-Tex graft shunt [ascending aorta to right pulmonary artery (RPA)] 9 years before.
Intraoperative TEE revealed a large subaortic VSD measuring 1.35 cm in size with right to left shunt, overriding of the aorta, right ventricular hypertrophy, normal mitral and tricuspid valves, RPA of 0.5 cm and left pulmonary artery of 1.3 cm. The shunt was visualized in the upper-esophageal short axis view at 0° as a linear echogenic structure between ascending aorta and the RPA [Figure 1]. Color Doppler revealed turbulent flow with a shunt diameter of 4 mm [Figure 2], [Video 1]. Despite best efforts, a good quality spectral Doppler could not be obtained; hence, the gradient could not be measured. It may be noted that while the lower (pulmonary) end can be clearly seen opening into the RPA, the upper (aortic) end is poorly visualized. This may be related to the fact that the upper end was anastomosed to the anterior wall of the aorta (farther from the TEE probe). However, the lie of the shunt is classically along the aortic wall medial to the superior vena cava. This can be better appreciated in the video.
Figure 1: Upper esophageal short axis view (0o) showing the central shunt as a linear echogenic structure (arrow) between ascending aorta and the right pulmonary artery. (SVC: superior vena cava, RPA: right pulmonary artery, AA: ascending aorta)
Scott PJ, Blackburn ME, Wharton GA, Wilson N, Dickinson DF, Gibbs JL. Transeosophageal echocardiography in neonates, infants and children: Applicability and diagnostic value in everyday practice of a cardiothoracic unit. Br Heart J 1992;68:488-92. [PUBMED] [FULLTEXT]
Correspondence Address: Deepak K Tempe Department of Anaesthesiology and Intensive Care, G. B. Pant Hospital, New Delhi-110002 India
Source of Support: None, Conflict of Interest: None