presented in subspecialty cardiology seminar for final year internal medicine residents in AAU-MF, Addis Ababa, Ethiopia

1. BASICS OF ECHOCARDIOGRAPHYAND PRINCIPLES OF DOPPLER ECHO Abraha Hailu August 29, 2010

2. Topic outline

3. 1. BASICS ultrasound (1923) vibrations of the same physical nature as sound but with frequencies above the range of human hearing, namely frequencies greater than 20,000 cycles per second. the diagnostic or therapeutic use of ultrasound and esp. a noninvasive technique involving the formation of a two-dimensional image used for the examination and measurement of internal body structures and the detection of bodily abnormalities a diagnostic examination using ultrasound

8. The depth of penetration:

9. 30 cm for a 1 MHz transducer,

10. 12 cm for 2.5 MHz transducer, and

11. 6 cm for a 5 MHz transducer

12. Air has a very high acoustic impedance, resulting in significant signal attenuation when imaging through lung tissue, especially emphysematous lung, or pathologic conditions such as pneumomediastinum or subcutaneous emphysema

14. ULTRASOUND TRANSDUCERS US transducers use a piezoelectric crystal to generate and receive ultrasound wavesImage formation: is related to the distance of a structure from the transducer, based upon the time interval between ultrasound transmission and arrival of the reflected signalThe amplitude is proportional to the incident angle and acoustic impedance, and timing is proportional to the distance from the transducer

17. 2. IMAGING MODALITIES Two dimensional (2-D) imaging : A 2D image is generated from data obtained mechanically (mechanical transducer) or electronically (phased-array transducer) The signal received undergoes a complex manipulation to form the final image displayed on the monitor including signal amplification, time-gain compensation, filtering, compression and rectification. M-mode: Motion or "M"-mode echocardiography is among the earliest forms of cardiac ultrasound The very high temporal resolution by M-mode imaging permits: identification of subtle abnormalities such as fluttering of the anterior mitral leaflet due to aortic insufficiency or movement of a vegetation. dimensional measurements or changes, such as chamber size and endocardial thickening, can be readily appreciated

18. A. 2-D ECHOCARDIOGRAPHY

23. IMAGING PLANES The long-axis plane is the plane perpendicular to the posterior and anterior surfaces of the body and parallel to the long axis of the heart

24. Sweeping begins at the base of the heart which appears on the rt of the screenThe left atrium, the mitral valve and the right ventricular outflow tract are seen.

26. Parasternal WindowRight Long-Axis ViewSweeping begins at the right atrium which is on the right of the screen. In this view we can see the right atrium and the right ventricle, with the tricuspid valve in between

28. The short-axis plane is the plane that runs parallel to the posterior and anterior surfaces of the body and transects the heart from its apex to its base encompassing all four cardiac chambers

29. Parasternal Short-Axis ViewsObtained from the parasternal window by rotating the transducer clockwise by 90ºHence, the image index marker is pointed toward the patient´s right supraclavicularfossa. A series of sweeps transect the heart from the base to the apex by changes in transducer position and angulation. There are three characteristic levels: 1) great vessels, 2) mitral valve, 3) ventricles.

30. Parasternal Short-Axis ViewGreat Arteries LevelSweeping begins at the left edge of the atrium which appears on the right of the screen

31. At aortic valve level it demonstrates all three aortic valve leaflets. The pulmonary valve, the right ventricular outflow tract, the right atrium and the left atrium are seen in this view.

32. Parasternal Short-Axis ViewGreat Arteries LevelIn this view we can see the pulmonary valve (PV) and pulmonary artery (PA) with right (RPA) and left branches (LPA).

33. Parasternal Short-Axis ViewMitral Valve LevelThe anterior and posterior mitral leaflets are seen as they open in diastole and close in systole

34. Parasternal Short-Axis ViewMitral Valve Level

35. The four-chamber plane is the plane that runs parallel to the posterior and anterior surfaces of the body and transects the heart from its apex to its base encompassing all four cardiac chambers

36. Apical WindowSweeping begins at the left edge of the heart which appears on the right of the screen.

37. 4-Chamber ViewIn this view we can see the left ventricle, the right ventricle, the left atrium and the right atrium. The tricuspid annulus lies slightly (up to 10 mm) closer to the apex than the mitral annulus. The septal and posterior tricuspid leaflets are seen in this view.

38. Apical Window5-Chamber ViewBy tilting the transducer anteriorly, the aortic root is seen in an oblique long view.

39. Apical Window2-Chamber ViewSweeping begins at the anterior face of the left ventricle which appears on the right of the screen. From the four-chamber view, the transducer is rotated anti-clockwise by 60º to obtain the two-chamber view of the left ventricle, the mitral valve and the left atrium.

40. Apical Window2-Chamber ViewThis view shows the LV, the LA and the MV. The LV shows the inferior wall on the left and the anterior wall on the right.

41. Subcostal Window4-Chamber ViewSweeping starts at the apex which appears on the right of the screen. A view of all four chambers shows the right ventricular free wall, the midsection of the interventricular septum and the posterolateral left ventricular wall. In this view, the interatrial septum is perpendicular to the direction of the ultrasound beam

42. Subcostal WindowThe inferior vena cava as it enters the right atrium and the central hepatic vein are seen.

43. Suprasternal Notch WindowSweeping begins at the descending aorta which appears on the right of the screen. The long-axis view shows the ascending aorta, the arch, the proximal descending aorta and the origins of the right brachiocephalic and left common carotid and subclavian arteries.

44. Suprasternal Notch Window

45. B. M-MODE ECHOCARDIOGRAPHY a single line of sight is included, the repetition frequency of the pulse transmission is very high and sampling rates of around 1800 cycles/sec are usedContinuously-moving structures may be identified more accurately when motion versus time, as well as depth, is displayed clearly on the M-mode recording

47. AORTIC VALVE AND LEFT ATRIUM

48. AORTIC VALVE AND LEFT ATRIUM The aortic root is moving anteriorly in systole and posteriorly in diastole. The left atrium is posterior to the aortic root. The aortic leaflet coaptation point is seen as a thin line in diastole. AO is measured in end-diastole and LA in end-systole.

50. In early diastole, the leaflets separate widely, with the maximum early diastolic motion of the anterior leaflet termed the E point. The leaflets move together in mid-diastole and then separate again with atrial systole, the A point. Closure at the end of diastole is termed C point.

51. M-mode recording perpendicular to the long axis of and through the centre of the left ventricle at papillary muscle level provides standard measurements of systolic and diastolic thickness and chamber dimensions:

52. Normal Values Left ventricular end-diastole: 37 - 57 mm (23 -31 mm/m²) Left ventricular end-systole: 21 - 40 mm (14 -21 mm/m²) Interventricular septum: 7 - 11 mm Posterior wall: 7 - 11 mm

53. 3. DOPPLER ECHOCARDIOGRAPHY BASIC PRINCIPLES: utilizes ultrasound to record blood flow within the cardiovascular system (While M-mode and 2D echo create ultrasonic images of the heart) is based upon the changes in frequency of the backscatter signal from small moving structures, ie, red blood cells, intercepted by the ultrasound beam

55. This difference in frequency between the transmitted frequency (F[t]) and received frequency (F[r]) is the Doppler shift:

57. With a stationary target (panel A): the carrier frequency [f(t)] from the transmitting transducer strikes the target and is reflected back to the receiving transducer at the reflected frequency [f(r)], which is unaltered

58. with a target moving toward the transducer (panel B): An increase in f(r) is seen

59. with a target moving away from the transducer (panel C): f(r) is reduced

63. For ø of 90º (perpendicular to blood flow), cosine ø = 0 and the Doppler shift is 0

64. For ø up to 20º, cos ø results in a minimal (<10 percent) change in the Doppler shift

67. By convention, time is displayed on the x axis and frequency shift on the y axis

73. Right Ventricular InflowCan be recorded from an apical approach. The pattern is similar to mitral flow.

74. Left Ventricular OutflowAn apical window is used with a pulsed Doppler sample volume positioned on the left ventricular side of the aortic valve. Note the narrow band of the systolic velocities.

75. Right Ventricular OutflowFrom a parasternal short-axis view, the sample volume is located in the right ventricular outflow tract. The Doppler shape is similar to the left ventricular outflow curve

76. Suprahepatic Vein FlowFrom the longitudinal subcostal view, the sample volume is located at the main suprahepatic vein. There are two positive waves, (A) and (V), and two negative ones, (X) and (Y).

77. DOPPLER MODALITIES Doppler methods used for cardiac evaluation : continuous wave doppler Pulsed wave doppler color flow doppler

79. Thus, there may be overlap in certain settings, such as:

80. stenoses in series (eg, left ventricular outflow tract gradient and aortic stenosis) or

83. An ideal Doppler profile is one with a smooth "outer" contour, well-defined edge and maximum velocity, and abrupt onset and termination

88. Because PWD repeatedly samples the returning signal, there is a maximum limit to the frequency shift that can be measured unambiguouslyThe maximum detectable frequency shift (the Nyquist limit) is one-half the PRFIf velocity exceeds the Nyquist limit, signal aliasing is seen with the signal cut off at the edge of the display and the top of the waveform appearing in the reverse partHigh-PRF increases the number of sample volumes

90. with flow toward the transducer displayed in orange/red

92. apical four chamber view with color flow Doppler during diastole This color signal is used to position a pulsed wave Doppler sample volume so that quantitatable signals of flow can be obtained from the pulmonary veins and from the mitral leaflet tips

94. The long axis parasternal view with superimposed color flow Doppler mapping of the left ventricular inflow and ouflow tracts obtained during diastole

95. the long axis parasternal view of the left ventricular outflow tract during systole; a normal color flow signal (red-orange) is seen in the left ventricular outflow tract. The occasional blue patches in the signal represent aliasing and suggest that the signal is at or exceeds the Nyquist limit.

96. Short axis view through the base of the heart with CFdoppler imaging short axis view recorded from the base of the heart: Color flow Doppler imaging during systole (panel A), demonstrates normal systolic flow from the right ventricular outflow tract (RVOT) to the main pulmonary artery (MPA). The flow signal is red in the proximal RVOT as it travels towards the transducer. As it moves at right angles to the interrogating beam the signal briefly disappears. When the flow turns away from the transducer and exits into the MPA it is coded blue. short axis view through the base of the heart during diastole: shows diastolic flow signal (red) from pulmonic valve (PV) denoting trivial pulmonary regurgitation (PR) which is found in 90 percent of normals.

99. Five chamber view from a 2-D echo shows a moderate amount of AR and left ventricular enlargement

100. The parasternal long axis view with color Doppler demonstrates severe AR associated with marked dilatation of the aortic root

102. velocity in the stenotic jet (V2)

106. REFERENCES CLINICAL ECHOCARDIOGRAPHY; HOSPITAL UNIVERSITARI VALL D´ HEBRON BARCELONA, Arturo Evangelista and HerminioGarcía del CastilloCo-authors: Teresa González-Alujas, Gustavo Avegliano, ZamiraGómez-Bosch; February 2004 UpToDate 17.3

107. THANKS FOR YOUR ATTENTION