Tissue Doppler Imaging in the evaluation of abdominal aortic pulsatility: a useful tool for the neonatologist

Abstract

(English) Sonographic cardiac evaluation of newborns with suspected aortic coarctation (AoC) should tend to demonstrate a good phasic and pulsatile flow and the absence of pressure gradient along a normally conformed aortic arch from the modified left parasternal and suprasternal echocardiographic views; these findings, however, may not necessarily rule out a more distal coarctation in the descending aorta. For this reason, the sonographic exam of newborns with suspected AoC should always include a Doppler evaluation of abdominal aortic blood flow from the subcostal view. Occasionally, however, a clearly pulsatile Doppler flow trace in abdominal aorta may be difficult to obtain due to the bad insonation angle existing between the probe and the vessel. In such suboptimal ultrasonic alignment situation, the use of Tissue Doppler Imaging instead of classic Doppler flow imaging may reveal a preserved aortic pulsatility by sampling the aortic wall motion induced by normal flow. We propose to take advantage of the TDI pattern as a surrogate of a normal pulsatile Doppler flow trace in abdominal aorta when the latter is difficult to obtain due to malalignment with the insonated vessel.Keywords Tissue Doppler Imaging Á Neonatology Á Aortic coarctation Á Newborn Á Pediatric cardiology Á Echocardiography Abstract (Italian) La valutazione ecocardiografica del neonato con sospetta coartazione aortica deve poter dimostrare, dalle proiezioni parasternale sinistra alta e soprasternale, un arco aortico normoconformato con traccia Doppler normale (flusso fasico) in assenza di gradiente transistmico; tali rilievi, tuttavia, non escludono la possibilità di una coartazione aortica più distale, sita in aorta discendente toracica. Per tale motivo, la valutazione ecografica neonatale nel sospetto di coartazione aortica deve sempre includere un'analisi Doppler del flusso in aorta discendente, visualizzata tramite approccio sottocostale. Talvolta, tuttavia, l'angolo che si viene a creare tra il fascio ultrasonoro e il vaso a questo livello può risultare subottimale ai fini di un adeguato campionamento Doppler che dimostri la presenza di flusso fasico e privo di run-off diastolico in aorta addominale. In tale situazione di allineamento non ottimale per l'analisi Doppler classica, la metodica TDI (Tissue Doppler Imaging) può rivelare una preservata pulsatilità aortica tramite l'analisi della motilità di parete del vaso indotta dal normale flusso fasico. Tale metodica di valutazione della pulsatilità di parete aortica potrebbe, se validata attraverso studi di numerosità adeguata sul neonato sano, rappresentare un adeguato surrogato di una traccia Doppler normale in aorta addominale nei casi in cui quest'ultima fosse difficoltosa da ottenere a causa di un malallineamento tra il vaso ed il fascio ultrasonoro esplorante.

Right Diaphragmatic Peak Motion Velocities on Pulsed Wave Tissue Doppler Imaging in Neonates: Method, Reproducibility, and Reference Values

“…In addition, the accuracy of a diaphragmatic amplitude assessment by M‐mode US can be strongly affected by the diaphragmatic subtlety of the neonate, especially in premature neonates. We considered it more feasible to measure the peak velocities of the right diaphragmatic excursions by using PW‐TDI because the diaphragmatic dome appears as a straight echogenic line, the same as the lateral mitral annulus or the abdominal aortic wall . Indeed, we measured exact time‐to‐peak velocities by sampling the muscle with the transducer lined up as parallel as possible to the diaphragmatic line moving to and from the transducer with breathing, providing a real‐time assessment of diaphragmatic kinetics, unlike M‐mode US.…”

The Progress of Advanced Ultrasonography in Assessing Aortic Stiffness and the Application Discrepancy between Humans and Rodents

“…Previous studies have revealed that TDI could be used to evaluate arterial stiffening in humans by measuring the vessel wall motion waveforms [ 35 , 66 ]. Multiple TDI-related parameters were applied in assessing the aortic elastic properties, including wall velocities and tissue strain (TDI-ε).…”