The aim of this paper is to highlight coronary investigation by transthoracic Doppler evaluation. This application has recently been introduced into clinical practice and has received enthusiastic feedback in terms of coronary flow reserve evaluation on left anterior coronary artery disease diagnosis. Such diagnosis represents the most important clinical application but has in itself some limitations regarding anatomical and technological knowledge. The purpose of this paper is to offer a didactic approach on how to investigate the different segments of left anterior and posterior descending coronary arteries by transthoracic ultrasound using different anatomical key structures as markers.
We will conclude by underlining that, nowadays, innovative technology allows complete evaluation of both major coronary arteries in many patients in a resting condition as well as during pharmacology stress-tests, but we often do not know it.
Coronary flow investigation by ultrasound: what can we get at present ?
The application of the latest ultrasound technology, in particular the 2nd harmonic, has opened new roads in ultrasound coronary evaluation. By applying anatomical knowledge and the newest technical applications it is nowadays possible to propose a complete coronary evaluation of the left anterior descending artery and of a part of the posterior descending coronary artery in clinical practice  [see Additional File 1].
Ultrassound coronary anatomy: reference point
Left anterior descending (LAD) coronary anatomy was the first artery investigated with ultrasound by transesophageal and transthoracic approach . This vessel is visible by using ultrasound from proximal to distal tract and following key anatomical structures through the delivery of an ultrasound beam in an off-axis approach starting from the classical apical approach (Fig 1,2).
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