Three simple but interesting transthoracic echocardiographic road maps for proximal superior vena cava visualisation...

Although much is known about the technical aspects of inferior vena cava visualization, it is much less about its counterpart: the superior vena cava (SVC). The aims of this study therefore, were to describe in detail the different possible two dimensional echocardiographic SVC visualization techniques in healthy young adults and to provide a series of values for its dimensions and Doppler signals.

The proximal SVC visualization through the three transthoracic windows was initially established in several adult patients, with or without cardiovascular implantable devices. Subsequently a group of 70 completely healthy adults (35 males and 35 females) were studied to determine the values of SVC dimensions and its pulse Doppler signal characteristics. The visualization windows included: a) Modified apical 5-champber view, b) Modified parasternal short axis view of great vessels and c) Modified subcostal view. The SVC dimensions were measured 3-5 cm above the RA-SVC junction at the end of both hold cardiac and respiratory cycles (systole, diastole and inspiration/expiration, respectively). The peak pulse Doppler velocities were only measured at the end-held expiration.

The largest end systolic proximal SVC dimensions at the end of the expiration and inspiration ranged from 8 to 14.0 mm (11 ± 2 mm) and 8.0-14.0 mm (11 ± 2 mm) respectively, and the highest S wave velocity ranged from 0.5 to 0.7 m/s (0.6 ± 0.0 m/s).

This study has provided a detailed technical description for transthoracic proximal SVC visualization in a group of 70 healthy adults and has furnished sets of values for its dimensions and Doppler signal parameters.