Contrast Echocardiography [antikvár]

FOREWORD Why a book on contrast echocardiography? Over the past dozen years enough experience has accumulated to warrant a more extensive treatment of this method. Furthermore, there are new developments that suggest increased clinical utility for contrast echocardiography in the future. This book aims to summarize the "state of the art" for those interested in echocardiography - presumably mainly cardiologists, but here and there those of a more technical bent will find useful information as well. We feel that a more basic understanding of microbubble dynamics is necessary to advance research for such applications as transmission through the lungs, videodensitometric quantitation of cardiac output, intracardiac shunts, etc. All of these topics are extensively dealt with. The reader will note that many of the clinical chapters are written by pediatric cardiologists. This is only natural, since shunt detection and analysis of flow relationships are relatively more important in congenital heart diseases, and currently represent the most important uses for contrast echocardiography in day-today practice. We would like to point out that the information content of contrast echocardiograms is frequently much greater than appreciated. The only information that many echocardiographers currently obtain from contrast studies is limited to a "yes-no" answer as to the presence or absence of a shunt or the proper identification of a structure. Systematic analysis of contrast echocardiograms reveals much more, however. For example, the slope of an individual trajectory on M-mode contrast echocardiography can yield similar information to that obtained by Doppler echocardiography: both yield the component of blood flow velocity towards or away from the ultrasonic transducer. A multigate Doppler system has even been developed at the University of Washington in Seattle that is capable of color-coding the Doppler signal and inserting it as a sort of contrast into an M-mode tracing. Thus, contrast can give "Doppler information" (velocity) and Doppler can be used to insert "contrast-like information" into an echocardiographic tracing! Contrast and Doppler echocardiography are likely to interact in a more direct manner as well: microbubbles are very strong contrast agents for Doppler ultrasound and may improve its signal-to-noise ratio. Contrast studies using microbubbles have just begun in Doppler echocardiography. The past development of echocardiography has concentrated first of all on anatomy and only later on physiology as deduced from motion of the anatomic