Basic transthoracic echocardiographyBMJ 2005; 330 doi: https://doi.org/10.1136/bmj.330.7505.1432 (Published 16 June 2005) Cite this as: BMJ 2005;330:1432
[posted as supplied by author]
Figure w1 and video clip. Apical four chamber view (normal). LV = left ventricle, LA = left atrium, RV = right ventricle, RA = right atrium.Click on the figure to see the video clip
Figure w2 and video clip. Apical two chamber view (normal). LV = left ventricle, LA = left atrium.Click on the figure to see the video clip
Figure w3 and video clip. Parasternal long axis view (normal). LV = left ventricle, LA = left atrium, RV = right ventricle, Ao = aorta.Click on the figure to see the video clip
Figure w4 and video clip. Parasternal short axis view showing mitral valve opening (normal).Click on the figure to see the video clip
Figure w5. M-mode through mitral valve (normal).
Figure w6. Continuous wave Doppler study of aortic valve (mixed aortic valve disease).
Figure w7. Pulse wave Doppler study of mitral inflow (normal).
Figure w8. Doppler tissue imaging of early diastolic mitral annulus velocity (e': in this case 9cm/s). This can be used to aid assessment of diastolic function.
Figure w9 and video clip. Colour flow mapping of severe tricuspid regurgitation in a patient with mitral and aortic stenosis. Note spontaneous echo contrast in the left atrium (right of image) and the small jet of blood passing from the left to right atrium through a patent foramen ovale.
[posted as supplied by author]
American Society of Echocardiography website. http://asecho.org/
Several useful links including free access to the American Society of Echocardiography clinical guidelines. PDF format guidelines available on this site include the comprehensive 1997 joint American College of Cardiology/American Heart Association and American Society of Echocardiography guidelines on the clinical use of echocardiography, along with the 2003 guideline update. http://www.asecho.org/freepdf/echoguide.pdf
Other guidelines available on this site include those on the preferred echocardiographic techniques recommended for clinical trials, the assessment of native valvular regurgitation, Doppler echocardiography and how to perform and report a transoesophageal echocardiogram.
The Echo Manual, Oh JK, Seward JB, Tajik AJ.
Excellent, readable and well-illustrated text giving very practical summary of how to perform clinical echocardiography.
ISBN: 078171205X, Format: Hardcover, 278 pages, Published: 1999, Edition Number: 2, Publisher: Lippincott Williams & Wilkins.
RESOURCES FOR PATIENTS
The American Society of Echocardiography has an excellent website (URL below) designed specifically for patients who are going to undergo an echocardiogram (including transoesophageal and stress echocardiograms). Although designed for an American audience, this has widely generalisable basic information.
The Cleveland Clinic provides brief but useful single page explanations about what to expect when undergoing a transthoracic, transoesophageal or stress echocardiogram (dobutamine or exercise)
WEB EXTRA BOX OR EXTRA TEXT: ECHOCARDIOGRAPHIC MODALITIES
Two-dimensional echocardiography images the heart in a tomographic slice and allows the motion of the cardiac structures to be seen in 'real-time'. Lung tissue impedes the passage of ultrasound. For this reason, the two most commonly used 'windows' for ultrasound imaging are between the ribs, over the cardiac apex, and at the left sternal edge. The most easily understood projection is the apical four chamber view, in which both ventricles are visualised from base to apex; along with both atrioventricular valves and both atria (figure w1). Rotation of the transducer along its axis images the left ventricular outflow tract and the two chambers of the left heart (apical long-axis and two-chamber views: figure w2). The parasternal views (figures w3 and w4) provide images of the mitral and aortic valves, left ventricle, left atrium, right heart and proximal aorta.
The ‘motion’ or M-mode echocardiogram uses ultrasound transmitted and received along a specific line-of-interest (figure w5). Cardiac motion is sampled approximately 1000 times per second, thereby increasing temporal resolution and enabling greater appreciation of the movement of cardiac structures. It is principally used to measure chamber size and wall thickness, but is also helpful to precisely time cardiac events.
The Doppler principle can be used to assess the direction and velocity of moving blood by measuring the change in frequency of an ultrasound impulse reflected from red blood cells. If they are moving towards the ultrasound transducer they will shorten the wavelength of the returning signal; if they are moving away the wavelength lengthen. The greater the velocity of red blood cells the larger the frequency shift. The returning signals are displayed graphically, with velocity on the vertical axis plotted against time horizontally. By convention, velocities obtained from blood moving towards the transducer are displayed above the baseline, and those moving away below (figure w6). In addition, the density of the signal reflects the number of red cells moving at the indicated velocity.
Continuous-wave Doppler signals are transmitted and received constantly. They measure frequency shifts along the entire length of the ultrasound beam and are most useful for measuring high velocities (such as those that occur across a stenotic aortic valve: figure w6). The beam can be steered within the two-dimensional image so that specific areas of the heart can be interrogated. The signal can, however, originate from any point along the length of the beam.
Pulsed-wave Doppler signals are transmitted intermittently and received only after a set delay. This enables the velocity of blood within a defined area to be examined, but limits the maximum velocity that can be measured. Its main uses are to determine the pattern of ventricular filling through the mitral valve in diastole (figure w7), to assess flow patterns in the pulmonary and hepatic veins and to measure the blood velocity in the left ventricular outflow tract. Doppler tissue imaging, using low frequency ultrasound, can be used to measure the slower velocities of myocardial tissue. This is particularly useful in measuring the velocity of the mitral valve annulus during diastole – an indicator of myocardial relaxation that is relatively unaffected by loading conditions and is helpful in defining diastolic function (figure w8).
Colour flow mapping superimposes multiple pulse-wave Doppler signals onto the two-dimensional echocardiographic image and ascribes a colour code to each velocity. Normal blood flow is laminar (with similar direction and velocity) and is shown in a uniform colour; with red, conventionally, coding for blood flow towards the transducer, and blue away. As with any pulse-wave signal, the time delay between transmission and receipt limits the ability to measure high velocities. When blood flow exceeds this threshold it results in ‘aliasing’, whereby a reversal of colour occurs. Turbulent flow induces a range of velocities. This can be represented visually using multiple colours to create a ‘kaleidoscope’ reflecting the multitude of differing velocities present. Alternatively, the variation in velocities can be represented using a ‘variance’ colour, usually green (figure w9).
- PaperValue of the electrocardiogram in identifying heart failure due to left ventricular systolic dysfunctionPublished: 27 January 1996; BMJ 312 doi:10.1136/bmj.312.7025.222
- General PracticeRisk assessment of left ventricular systolic dysfunction in primary care: cross sectional study evaluating a range of diagnostic testsPublished: 22 January 2000; BMJ 320 doi:10.1136/bmj.320.7229.220
- Correction Published: 15 September 2005; BMJ 331 doi:10.1136/bmj.331.7517.613-a
- PaperCross sectional study of contribution of clinical assessment and simple cardiac investigations to diagnosis of left ventricular systolic dysfunction in patients admitted with acute dyspnoeaPublished: 29 March 1997; BMJ 314 doi:10.1136/bmj.314.7085.936
- High levels of bad cholesterol in early middle age are linked to CVD risk decades later, study findsBMJ December 04, 2019, 367 l6814; DOI: https://doi.org/10.1136/bmj.l6814
- Taking antihypertensives at bedtime nearly halves cardiovascular deaths when compared with morning dosing, study findsBMJ October 23, 2019, 367 l6173; DOI: https://doi.org/10.1136/bmj.l6173
- Physical activity: government must tackle “stark inequalities,” says BMABMJ October 23, 2019, 367 l6168; DOI: https://doi.org/10.1136/bmj.l6168
- Former footballers are more likely to die from neurodegenerative disease, study findsBMJ October 21, 2019, 367 l6130; DOI: https://doi.org/10.1136/bmj.l6130
- UK must become more self reliant for sake of healthcare workforce, says top doctorBMJ October 16, 2019, 367 l6061; DOI: https://doi.org/10.1136/bmj.l6061