An understanding of the physical principles that underlie echocardiography is essential to understanding its usefulness and limitations.
Principles of Ultrasound and InstrumentationĮchocardiography is based on the standard principles of ultrasound imaging in which high-frequency sound waves in the 1- to 10-MHz range are emitted from piezoelectric crystals housed in a transducer, traverse through internal body structures, interact with tissues, reflect back to the transducer, and are then processed by microcomputers to generate an image. Knowledge of its basic principles, uses, and limitations is becoming essential for all physicians who care for patients with cardiovascular problems. The advent of small, handheld ultrasound devices, which complement the physical examination, will further open this field to a wide array of practitioners who may not currently practice echocardiography. Thus echocardiography is best described as an “examination” rather than a “test.” Although cardiologists receive this training routinely, a growing number of noncardiologists, including emergency physicians, anesthesiologists, intensivists, and others, are increasingly using echocardiography in their practice. Both acquisition and interpretation of echocardiograms require substantial training and skill.
Technical advancements in echocardiography over the past several decades have led to progressively improved diagnostic capabilities, including major advances in three-dimensional echocardiography, miniaturization of equipment leading to handheld echocardiography units, and contrast echocardiography for better cavity visualization and assessment of myocardial perfusion.īecause two-dimensional echocardiography is not a tomographic technique like cardiac computed tomography (CT) or cardiac magnetic resonance (CMR) ( see Chapters 17 and 18), acquisition of ultrasound images is dependent on an operator-either a sonographer or a physician-applying an ultrasound transducer to a patient’s chest. In most echocardiography laboratories, standard transthoracic echocardiography (TTE) is complemented by transesophageal echocardiography (TEE), which offers improved resolution because of closer proximity of the transducer to cardiac structures, and by stress echocardiography, which is routinely used to assess myocardial ischemia and valvular function with exercise. Furthermore, the real-time nature of echocardiography makes it uniquely suited to noninvasive assessment of systolic and diastolic function and intracardiac hemodynamics. Echocardiography provides detailed data on cardiac structure, including the size and shape of cardiac chambers, as well as the morphology and function of cardiac valves. When compared with other imaging methods, echocardiography can be performed quickly, with minimal patient inconvenience or discomfort, and provides immediate clinically relevant information at relatively low cost. SYSTEMIC DISEASES AND ECHOCARDIOGRAPHY, 236ĬARDIAC PROCEDURES AND FUTURE DIRECTIONS, 249Įchocardiography remains the most commonly used and comprehensive cardiac imaging modality and is generally considered the first test of choice for assessing cardiac structure and function in most clinical situations. Role of Echocardiography in Surgery for Endocarditis, 236 Malignant Involvement of the Pericardium, 228 Other Cardiomyopathies with Regional or Global Variations in Myocardial Composition, 208 Late Complications of Myocardial Infarction, 206Įchocardiographic Prognostic Indicators after Myocardial Infarction, 206 Mechanical Complications after Myocardial Infarction, 204 THE STANDARD ADULT TRANSTHORACIC ECHOCARDIOGRAPHIC EXAMINATION, 184Īssessment of Cardiac Structure and Function, 184ĮCHOCARDIOGRAPHY IN THE CONTEXT OF CARDIAC IMAGING, 200 Pulsed-Wave and Continuous-Wave Doppler, 181īlood Flow Profiles and Doppler Signals, 182ĭoppler Echocardiography in Practice, 183Īssessment of Flow and Continuity Equation, 184 PRINCIPLES OF ULTRASOUND AND INSTRUMENTATION, 179
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