Echocardiogram — Purpose, Procedure & Normal Values | MyMedicPlus

An echocardiogram (echo) is a cardiac imaging procedure that uses high-frequency ultrasound waves (typically 2–7 MHz) emitted from a transducer to produce real-time, dynamic images of the heart's four chambers, four valves, pericardium, aortic root, and surrounding great vessels. Unlike an ECG, which records only cardiac electrical signals, an echocardiogram directly visualises the mechanical function of the heart — how the chambers contract and relax, how valves open and close, and whether myocardial walls move normally. The most commonly performed type is the transthoracic echocardiogram (TTE), in which the ultrasound transducer is pressed against the chest wall at multiple acoustic windows to generate two-dimensional (2D) images, M-mode tracings, and Doppler waveforms. A transoesophageal echocardiogram (TOE or TEE) passes a specialised miniaturised transducer mounted on a flexible endoscope down the oesophagus, which lies immediately posterior to the left atrium, providing far superior image resolution — particularly for the mitral valve, left atrium, atrial appendage, and thoracic aorta. Three-dimensional (3D) echocardiography, stress echocardiography (exercise or pharmacological with dobutamine), and contrast echocardiography (using intravenous microbubble agents) extend diagnostic capability further. Echocardiograms are performed by trained cardiac sonographers (echocardiographers) and reported by consultant cardiologists in echocardiography laboratories, at the bedside in intensive care, and during cardiac surgery.

An echocardiogram is ordered to assess cardiac structure and function across a broad spectrum of indications. In heart failure, it establishes the left ventricular ejection fraction (LVEF), distinguishing heart failure with reduced ejection fraction (HFrEF, LVEF <40%) from heart failure with preserved ejection fraction (HFpEF, LVEF ≥50%), and guides guideline-directed medical therapy selection. Post-myocardial infarction echo assesses infarct size, regional wall motion abnormalities, left ventricular thrombus, mitral regurgitation, and mechanical complications. In valvular heart disease, it grades the severity of aortic stenosis, aortic and mitral regurgitation, mitral stenosis, and tricuspid valve disease. Other indications include investigation of a new or changing cardiac murmur, suspected congenital heart disease (septal defects, patent ductus arteriosus, complex anatomy), hypertrophic obstructive cardiomyopathy (HOCM), dilated cardiomyopathy, suspected pericardial effusion or cardiac tamponade, evaluation of intracardiac masses or thrombus, pre- and post-cardiac surgical monitoring, infective endocarditis diagnosis and complication assessment, aortic root and ascending aorta aneurysm measurement, and pulmonary arterial pressure estimation via tricuspid regurgitation jet velocity to diagnose pulmonary hypertension.

For a standard transthoracic echocardiogram (TTE), no fasting, bowel preparation, or medication changes are required. Continue all regular cardiac and non-cardiac medications as usual on the day of the test. Wear a two-piece outfit to allow easy access to the chest from the side — the sonographer needs to reach multiple positions on the left chest, sternum, and upper abdomen without fully undressing you. For a transoesophageal echocardiogram (TOE), fast for at least 4–6 hours before the procedure (water permitted up to 2 hours prior) to reduce aspiration risk during probe passage. Arrange a driver or companion to take you home after a TOE, as you will receive intravenous sedation (usually midazolam with or without fentanyl) and will be unfit to drive for the remainder of the day. Remove dentures, partial plates, or dental retainers before a TOE. Inform your cardiologist or sonographer of any swallowing difficulties, history of oesophageal stricture, previous oesophageal surgery, or oesophageal varices if a TOE is planned. For a stress echo, be prepared to exercise on a treadmill or stationary bicycle.

For a TTE, you lie on your left side (left lateral decubitus position) on a padded examination couch — this position shifts the heart closer to the chest wall and improves image quality. Three ECG electrodes are placed on the chest to allow simultaneous electrocardiographic gating of the images. The cardiac sonographer applies ultrasound gel to the transducer and presses it sequentially against four main acoustic windows: the parasternal window (left of the sternum, 2nd–4th intercostal space), the apical window (cardiac apex at the 5th intercostal space mid-clavicular line), the subcostal window (below the xiphisternum), and the suprasternal window (above the sternum). At each window, multiple imaging planes are acquired — long axis, short axis, four-chamber, two-chamber, and five-chamber views. Pulse-wave Doppler, continuous-wave Doppler, and colour-flow Doppler measure blood flow velocity, direction, and turbulence across valves and within chambers. Tissue Doppler imaging (TDI) assesses myocardial velocities at the mitral annulus, providing information about diastolic function. The procedure takes 30–45 minutes and is entirely painless; you may feel mild pressure from the transducer. The sonographer captures a comprehensive set of still and video clips for the cardiologist to review and report on.

The echocardiogram report quantifies cardiac structure and function using standardised measurements. Left ventricular ejection fraction (LVEF) — Normal 55–70% (some guidelines define normal as ≥55%); Mildly reduced 45–54%; Moderately reduced 30–44%; Severely reduced <30% (this threshold defines HFrEF and triggers triple neurohormonal therapy). Left ventricular end-diastolic diameter (LVEDD) — Normal 42–58 mm; above 60 mm indicates left ventricular dilatation. Interventricular septum and posterior wall thickness — Normal 6–11 mm; above 13–15 mm suggests hypertrophy. Aortic valve area (AVA) — Normal >2.0 cm²; Mild stenosis 1.5–2.0 cm²; Moderate stenosis 1.0–1.5 cm²; Severe aortic stenosis <1.0 cm². Peak aortic jet velocity — Severe aortic stenosis >4 m/s; mean pressure gradient >40 mmHg. Mitral annular e' velocity — Normal ≥10 cm/s (septal); <7 cm/s indicates impaired diastolic relaxation. E/e' ratio — Normal <8; >14 suggests elevated left ventricular filling pressure. Right ventricular systolic pressure (RVSP) — estimated from tricuspid regurgitation jet; >35 mmHg suggests pulmonary hypertension. The report also systematically describes all four valves, pericardium, inferior vena cava collapsibility, and any intracardiac masses. Preliminary findings may be discussed with you immediately after the scan; the formal cardiologist report is typically available within 24–72 hours.

A transthoracic echocardiogram uses ultrasound waves only — there is no ionising radiation whatsoever — and is completely safe with no known risks for the patient. Diagnostic ultrasound has been used in cardiac imaging for over 50 years with an excellent safety record across all patient groups including pregnant women. The main practical limitation of TTE is image quality variability related to patient factors: obesity, barrel-shaped chest deformity from emphysema or COPD, chest wall scars, and large breast tissue can reduce acoustic window access, producing technically poor images in approximately 10–15% of patients. In such cases, intravenous ultrasound contrast agents (SonoVue, Optison) can enhance endocardial border definition. If TTE image quality is persistently inadequate, cardiac MRI provides superior structural and functional assessment without radiation. A TOE carries small but real procedural risks: oropharyngeal discomfort, gagging, temporary odynophagia (painful swallowing) for 1–2 days, oesophageal perforation (incidence <0.01%), aspiration, and sedation-related cardiovascular and respiratory depression requiring monitoring. Echocardiography provides limited direct assessment of coronary artery anatomy — stress echocardiography, myocardial perfusion scintigraphy, or CT coronary angiography is needed to evaluate coronary artery disease and ischaemia-induced wall motion abnormalities.