echocardiography

Echocardiography is an ultrasound-based imaging technique that visualizes the heart in motion and provides measurements of its chambers, valves, and surrounding structures. By emitting high-frequency sound waves and receiving their echoes, it produces real-time images of cardiac anatomy. Doppler assessment analyzes the speed and direction of blood flow, allowing estimation of pressures and evaluation of valvular and intracardiac hemodynamics.

The most common form is transthoracic echocardiography (TTE), a noninvasive study performed with a handheld transducer on the chest. Transesophageal echocardiography (TEE) uses an ultrasound probe placed in the esophagus for higher-resolution views of posterior structures and in cases where TTE image quality is limited. Modern echocardiography includes two-dimensional imaging, three-dimensional imaging, and various Doppler techniques such as color flow, pulsed-wave, and continuous-wave Doppler. Tissue Doppler and strain imaging assess myocardial velocities and deformation for cardiac function and prognosis.

Clinical indications include evaluation of heart size and function, assessment of valvular disease (stenosis or regurgitation), investigation of suspected cardiomyopathy or congenital heart disease, pericardial disease and effusions, pulmonary hypertension, and intraoperative or critical care monitoring. Echocardiography provides measurements such as left ventricular ejection fraction, chamber dimensions, valvular gradients, and estimated filling pressures.

Advantages include wide availability, lack of ionizing radiation, and real-time functional information. Limitations include operator dependence and image quality variability due to body habitus or lung disease. TEE, while more invasive, carries anesthesia risks and small but real risks of esophageal injury. Studies are guided by professional societies, with routine oversight by cardiologists and trained sonographers.

History and context: Echocardiography began in the mid-20th century with the development of cardiac Doppler techniques by Inge Edler and Hellmuth Hertz, and has since evolved into comprehensive multimodal imaging. It is routinely integrated with clinical assessment and other imaging modalities to diagnose and manage cardiovascular disease.