2 EchocardiographyEchocardiography is the application of ultrasound to evaluate cardiac anatomy and physiology.There are several different ways that ultrasound is used in echocardiography to assess cardiac structure/function.These different ways (or modalities) will be discussed in the following slides.
3 EchocardiographyThe standard/basic modalities that are commonly used in echo are:2-Dimensional or “real-time” echoM-Mode or “motion mode” echoColor doppler echo, andSpectral doppler echo
5 2-Dimensional EchoUltrasound waves are generated by the transducer and penetrate into the soft tissue.Each tissue density interface within the body reflects part of the ultrasound wave back to the transducer.The ultrasound platform forms an image based upon the arrival time and intensity of the returned ultrasound wave.In 2 dimensional echocardiography, each image is formed from a single fan shaped slice of returning ultrasound.Images are formed rapidly, allowing “real-time” motion of cardiac structures to be displayed.
6 2-Dimensional Echo Right Ventricle (RV) Left Ventricle (LV) Interventricular Septum (IVS)This is a (static image) cross section of the heart obtained from the left parasternal border (parasternal short axis).Imagine the heart cut in half at it’s midsection along the short axis (ventricular level).Displayed in this view:RVIVSLV
7 2-Dimensional EchoTo the left is a “real time” 2-dimensional image of the heart from the parasternal short axis view.Note how in systole, the walls of the left ventricle thicken and contract in unison, and the cavity size (dark area) decreases. This is an example of normal systolic function.The two lateral structures within this cavity are the papillary muscles of the left ventricle (part of the mitral apparatus).
8 2-Dimensional EchoThe following slides are examples of normal anatomy and cardiac function in “real time”2-dimensional echocardiography (echo).These views are a sample of the most common views that you will see in echo.Each new view will be prefaced by a static image that defines cardiac anatomy.
9 2-D Echo (Parasternal Long Axis) RVIVSLVMitral ValveAortic ValveLV ApexLeft AtriumThe parasternal long axis view is obtained from the left sternal border.Displayed in this view:RVIVSLVAortic Valve (AV)Mitral Valve (MV)Left Atrium (LA)
10 2-D Echo (Parasternal Long Axis) To the left is a “real time” clip of the parasternal long axis viewNote that walls of the left ventricle (IVS and LV posterior wall - bottom) contract simultaneously and with equal thickening of the myocardium (heart muscle).In diastole, the mitral valve is open, in systole the mitral valve is closed.Conversely, in diastole – the aortic valve is closed, and in systole the aortic valve is open.
11 2-D Echo (Parasternal Short Axis) This is a (static image) cross section of the heart obtained from the left parasternal border (parasternal short axis).Imagine the heart cut in half at it’s midsection along the short axis (ventricular level).Displayed in this view:RVIVSLVRVIVSLV
12 2-D Echo (Parasternal Short Axis) To the left is a “real time” 2-dimensional image of the heart from the parasternal short axis view.This view is a perpendicular view of the parasternal long axis viewIn this view, the right ventricle normally presents as a concave attachment (upper left) to the left ventricle
15 2-D Echo (Apical 4 Chamber) As it’s name would imply, this is a view that displays all 4 chambers of the heart.This view is obtained with the transducer placed at the 4-6th left intercostal space (imaging from the apex)The apex of the heart is displayed at the top of the image (ventricles on top, atria on the bottom)Note how the left heart structures are displayed to the right and vice versa.IVSLVRVMVTVRALA
16 2-D Echo (Apical 4 Chamber) To the left is a “real time” clip of the apical 4 chamber viewNote that walls of the left ventricle (IVS and LV lateral wall – far right) contract simultaneously and with equal thickening of the myocardium (heart muscle).In diastole, the mitral valve is open, in systole the mitral valve is closed.
17 2-D Echo (Apical 5 Chamber) Left Ventricular Outflow Tract (LVOT)The apical 5 chamber is a slight modification (anterior angulation) from the apical 4 chamber.This view brings into view the left ventricular outflow tract and the aortic valve.The right side of the heart is somewhat obscured by the angle of transducer orientation.LVMVAVLA
18 2-D Echo (Apical 5 Chamber) In this view the mitral and aortic valves are visualizedNote again that in diastole, the mitral valve is open, in systole the mitral valve is closed.Conversely, in diastole – the aortic valve is closed, and in systole the aortic valve is open.
20 Motion Mode (M-Mode) One of the first types of echocardiography M-Mode imaging utilizes a single “ice-pick” sector of the “real-time” image to display cardiac motion with a (significantly) more rapid frame rate across time.Depth is displayed on the y-axis, and time is displayed on the x-axis.
21 Motion Mode (M-Mode)To the left is displayed a 2-D image of a parasternal short axis view.The red line represents the user defined “sampling line” for the display of motion (m-mode)Note that the line sampled cuts through (or displays) in order from top to bottom:RV freewallIVSLV posterior wall
22 Motion Mode (M-Mode)In M-Mode, the motion of all cardiac structures along the sample line is displayed over time (left to right)Systole and Diastole are evident by the decrease in LV cavity size.The motion of the IVS and LV Posterior wall are synchronous in contraction.
24 Color Flow DopplerUtilizing the measured frequency shifts of blood flow though the heart as sampled by ultrasound (i.e. Doppler Shift), blood flow direction and velocity can be obtained.Color (flow) doppler echocardiography assigns a color to the blood flow within a sampled area.Blood flow is assigned a color based upon 2 factorsFlow directionFlow velocity
25 Color Flow DopplerIn color doppler echocardiography, a “color scale” is utilized. This scale determines the color of the blood flow sampled and is typically displayed in the upper left or right of the imaging screen.To the left is a typical color scale. Blood that is traveling toward the transducer (or top of image) is coded red and blood traveling away from the transducer (or bottom of image) is coded blue.Each direction has shades at their extreme ends to depict a higher velocity of flow. The numbers (56cm/sec in this example) represent the higher ends of flow velocity.
26 Color Flow Doppler To the left is an example of color flow doppler. This apical 5 chamber view in diastole shows the mitral valve open and blood flowing into the LV and toward the top of the image (labeled red).The highest velocity of the mitral inflow can be identified by it’s yellow hue (as indicated by the color scale in the top right)Note the sample area is outlined by a light blue box.LVLA
27 Color Flow Doppler This is the same apical 5 chamber view in systole. Note how the blood leaving the left ventricle through the LVOT is coded blue.Also of note is a small amount of mitral regurgitation. This is displayed as a blue signal that is passing though the closed mitral valve during systole.LVLA
28 Color Flow DopplerThis is the real time clip that demonstrates color flow doppler interrogation of the mitral and aortic valves (apical 5 chamber view)Again, in systole, note that there is a small amount of blue color flowing retrograde into the left atrium. This is mild mitral regurgitation.
29 Color Flow DopplerTo the left is another example of color doppler interrogation from the apical 4 chamber view.In systole, note again - that there is a mitral regurgitation. During systole there should be no blue signal present in the left atrium. This is classified as moderate mitral regurgitation.
57 Spectral DopplerSpectral doppler or “pulsed wave” doppler is used to measure blood flow velocity at a discrete point within the heart. (e.g. mitral valve, aortic valve, LVOT, etc.)A user defined “sample volume” is placed where the measurement is desired, and the high frequency doppler shift of the moving blood is sampled.The blood flow velocity is then displayed across time. (velocity on the y-axis, time on the x-axis)
58 Spectral DopplerThis is a static image of an apical 5 chamber view in systole.Color flow doppler displays a blue signal as blood moves away from the transducer (or towards bottom of the screen)The pulsed wave sample volume is placed in the LVOT (dotted line with slightly larger dot that represents area to be sampled)LVOTSample Volume
59 Spectral DopplerThis is a typical pulsed wave/spectral doppler display.The small picture in the upper right displays where the sample volume is placed (left ventricular outflow tract)Blood that is traveling toward the transducer or top of the screen is posted above the baseline. Conversely, blood that is traveling away from the transducer is posted below the baseline.
60 Spectral DopplerA 3-lead ECG is displayed (in this example) in green and runs across the top of the doppler display.With the sample volume placed in the left ventricular outflow tract (LVOT), during systole blood flow is moving away from the transducer (or toward the bottom of the screen) and is therefore posted below the baseline. This display may be “frozen” so that velocity measurements can be obtained.
61 Spectral DopplerThis is an example of the pulsed doppler display of mitral valve flow (or LV inflow). Blood flow is moving toward the transducer, so it is displayed above the doppler baselineNote that there are 2 distinct filling phases. The first diastolic filling phase is “passive filling” and is followed by “active filling” precipitated by left atrial contraction.The doppler term for these filling phases are called the “E” and “A” waves respectively.EAPassiveActiveDiastoleSystoleDoppler Baseline
63 Regional LV Systolic Function LV systolic function can be divided into 2 categories: Regional and Global.Regional systolic function describes the function of specific segments or walls of the left ventricular myocardium.Typically regional function is described in terms of:Normal: normal motion and thickeningHypokinetic: depressed motion or thickeningAkinetic: no motion or thickeningDyskinetic: motion in the wrong direction with no thickeningAneurysmal: “bulging out” from normal LV geometry with no thickeningTardokinetic: late motion or thickening (typical IVS motion with BBB or Paced rhythm)
64 Global LV Systolic Function Global systolic function describes how the LV pump is functioning as a whole, regardless of how the individual segments of the left ventricle myocardium are functioning.For example: global LV systolic function may be preserved even in the setting of myocardial infarction involving one specific area of the heart causing “regional” LV systolic dysfunction.The two most commonly used methods in echocardiography to quantify global LV systolic function are:Ejection FractionStroke Volume
65 Ejection Fraction (Method of Disks) Ejection fraction is a routinely measured index of global systolic function in echocardiographyThe left ventricular cavity area is measured in two long axis planes (Biplane) in both systole and diastole.From these areas, volumes are produced and the ejection fraction is calculated.
66 Ejection Fraction (Method of Disks) Below is an example of one of the two planes used to calculate ejection fraction (apical 4 chamber view). In each example, the LV is traced and long axis identified by a line running from the mitral annulus level to the LV apex.Each traced area is subdivided into “disks” along the long axis plane, and the volume of the disks is added yielding a total cavity volume.LVRVRALALVRVRALA
67 Stroke Volume (Doppler Method) Utilizing doppler echocardiography, stroke volumes can be obtained with relative ease.This doppler volume calculation is based upon the volume calculation of a cylinderBy tracing the doppler velocity profile of the LVOT, two parameters are measured:Average systolic flow velocity (cm/sec)Ejection time (sec)This traced measurement is known as the VTI or velocity time integral
68 Stroke Volume (Doppler Method) This is an example of a LVOT VTI.Note that the units of measure are centimeters (for distance).
69 Stroke Volume (Doppler Method) As distance is defined as: average velocity X time, the “stroke distance” can be calculated. That is, the distance that the blood travels with one “stroke” through the left ventricular outflow tract.By measuring the LVOT diameter and calculating its area, we have the last part of the equation needed to calculate the volume of a cylinder (the base).
70 Stroke Volume (Doppler Method) Because the LVOT diameter is relatively constant in size regardless of systolic function, the LVOT VTI can be used to follow changes in systolic function on almost a “beat to beat” basis. This method has lent itself well to the process of CRT.Care must be taken by the sonographer however, to ensure that the doppler sample volume remains steady, and that respiratory changes in the hearts position are taken into account. This is typically done by taking doppler measurements at end expiratory apnea and measuring multiple cycles to ensure reproducibility.
71 Atrioventricular (AV-PV) Optimization with Echocardiography
72 Atrioventricular Optimization There are currently two commonly used methods for atrioventricular optimization:Ritter MethodIterative MethodAn example of the Iterative Method will be shown in the following slides
73 Atrioventricular Optimization The goal of AV optimization is to give the atria time to complete its active filling phase (maximizing atrial contribution of volume/pressure) prior to the onset of ventricular contraction.Doppler echocardiography allows us to track the “active filling” phase or “A” wave in real-time.AE
74 Atrioventricular Optimization The objective, using doppler echocardiography, is to set the AV/PV interval to the shortest time possible that allows the completion of active filling – without truncation of the A wave.This is performed by setting the initial time high (usually around ms) and decreasing in ms intervals until obvious truncation is seen. Then increasing in intervals of 5-10 ms until truncation is no longer evident.
75 Atrioventricular Optimization Starting at 200 ms, the E and A waves are merged. As the time is decreased in 20 ms intervals, we can see the E and A waves (although still somewhat merged) begin to separate.Note that the doppler waveform of the A wave is symmetrical in its upslope and downslope. There is no truncation evident at the lowest setting of 160 ms. At this point we know that we need to decrease the time further.200 ms180 ms160 msAMergedE
76 Atrioventricular Optimization Proceeding from 160 ms, the time is lowered in 20 ms intervals. At 140 ms the A wave starts to lose its symmetry. Note how the downslope of the A wave is noticeably steeper than its upslope. This is truncation of the A wave.At 120 ms the truncation is more obvious.TruncationTruncation160 msA140 ms120 msE
77 Atrioventricular Optimization 200 msMergedIn this example the optimized setting was 160 ms.Note how as the time is decreased the A wave shifts to the right.It is important to note that when obtaining these doppler parameters, multiple samples should be taken, and every attempt should be made to take samples at end expiratory apnea for reproducibility.160 msAETruncation120 ms