BASICS OF ECHOCARDIOGRAGHYDr Ramachandra Barik, DNB(Cardiology)NIMS,Hydearabad-500082,India.

First, ultrasound can be directed as a beam and focused

It obeys the laws of reflection and refraction It is poorly transmitted through a gaseous

medium and attenuation occurs rapidly, especially at higher frequencies.

The amount of reflection, refraction, and attenuation depends on the acoustic properties of the various media through which the ultrasound beam passes.

Within soft tissue, velocity of sound is fairly constant at approximately 1,540 m/sec (or 1.54 m/msec, or 1.54 mm/µsec).

Wave length(in millimeters) = 1.54/f, where f is the transducer frequency (in megahertz).

higher frequency ultrasound has less penetration compared with lower frequency ultrasound.

The loss of ultrasound as it propagates through a medium is referred to as attenuation.

Attenuation has three components: absorption, scattering, and reflection.

Attenuation always increases with depth and is also affected by the frequency and the type of tissue.

Attenuation may be expressed as “half-value layer”or “half-power distance”which is a measure of the distance that ultrasound travels before its amplitude is decreased to one half its original value

As a rule of thumb, the attenuation of ultrasound in tissue is between 0.5 and 1.0 dB/cm/MHz.

The velocity and direction of the ultrasound beam as it passes through a medium are a function of the acoustic impedance of that medium.

Acoustic impedance (Z, measured in rayls) is simply the product of velocity (in meters per second) and physical density (in kilograms per cubic meter).

The phenomena of reflection and refraction obey the laws of optics and depend on the angle of incidence as well as the acoustic mismatch.

Small differences in velocity also determine refraction.

These properties explain the importance of using an acoustic coupling gel during transthoracic imaging.

This is primarily due to the very high acoustic impedance of air.

Specular echoes are produced by reflectors that are large relative to ultrasound wavelength. Eg: endocardial and epicardial surfaces, valves, and pericardium.

Targets that are small relative to the wavelength of the transmitted ultrasound produce scattering, and such objects are sometimes referred to as Rayleigh scatterers.

Scattered echoes provide the substrate for visualizing the texture of gray-scale images.

The term speckle is used to describe the tissue-ultrasound interactions that result from a large number of small reflectors within a resolution cell.

Most commercial transducers employ ceramics, such as ferroelectrics, barium titanate, and lead zirconate titanate.

Dampening (or backing) material, which shortens the ringing response of the piezoelectric material after the brief excitation pulse. An excessive ringing response lengthens the ultrasonic pulse and decreases range resolution.

At the surface of the transducer, matching layers are applied to provide acoustic impedance matching between the piezoelectric elements and the body

An important feature of ultrasound is the ability to direct or focus the beam .

The proximal or cylindrical portion of the beam is referred to as the near field or Fresnel zone.

When it begins to diverge, it is called the far field or Fraunhofer zone.

Maximizing the length of the near field is an important goal of echocardiography.

The ultrasound beam is both focused and steered electronically, beam manipulation can be achieved through the use of phased array transducer.

By adjusting the timing of excitation and adjustments in the timing allow the beam to be steered through a sector arc, resulting in a two-dimensional image.

electronic transmit focusing of the beam can either be fixed or adjustable, and the process is referred to as dynamic transmit focussing.

Focusing concentrates the acoustic energy into a smaller area, resulting in increased intensity .

By increasing beam intensity within the near field, the strength of returning signals is enhanced. An undesirable effect of focusing is its effect on beam divergence in the far field

Intensity varies across the lateral dimensions of the beam

It is customary to measure the beam width at its half amplitude or intens.

At high gain settings, the weaker portion of the ultrasound beam is recorded and beam width is greater.

Resolution has at least two components: spatial and temporal.

Spatial resolution - smallest distance that two targets can be separated .

Axial resolution

lateral resolution

Commercial echographs have repetition rates between 200 and 5,000 per second.

M-mode , pulse repetition rates of between 1,000 and 2,000 per second are used.

For two-dimensional imaging, repetition rates of 3,000 to 5,000 per second are necessary to create the 90-degree sector scan.

Because all the pulses are devoted to a single raster line, the temporal resolution is actually much higher for M-mode

• Requires more than one position.

• Tilting pt to left improves ultrasound windows.

• Rt lat decubitus-record aortic flow & congen disease.

• Subcostal imaging

• Suprasternal notch

• Sitting position

• Mid portion & base of lv ,both leaflets of MV ,AV ,AO root ,LA &RV.

• imaging plane is aligned parallel to long axis of lv.

• Reduced endocardial definition & wall motion analysis difficult.

• Medial angulation of the scan plane – RA & RV seen.

• one of the most important components of quantitation of ventricular function.

• Qualitative and quantitative data derived from echocardiography, e.g., LV dimensions and wall thickness, can influence patient management and serve as potent predictors of outcomes

• Chronic stable coronary artery disease, there is a consistent relationship between heart size and outcomes

• The same applies to patients without heart failure.• Framingham Heart Study patients without a history

of heart failure or myocardial infarction, LV size (by M-mode echocardiography) was an important predictor of subsequent risk of heart failure.

• M-mode line perpendicular to long axis of the heart and immediately distal to the tips of the mitral leaflets in thePLAX view

• diastolic measurements

septal wall thickness, the

LV internal diameter at end diastole (LVIDd) and posterior wall thickness.

In systole, the LV systolic diameter(LVIDs) is measured

• clockwise rotation of 90 degrees

• Pts lateral wall I placed to the observer”s right

• LV is displayed as if viewed from apex

• Apical level

• Papillary muscle level -

• Mitral valve level- Precise recording of mitral orifice in pts with MS.

-Basal level- aortic annulus, AV, coronory ostia, LA, TV, RVOT, PV & prox pa. -annulus regarded as clock face- LMCA at 4 & RCA at 11

-with slight superior angulation-bifurcation of PA

• Apical 4 chamber-After location of apical window ,all 4 chambers are optimally visualised when ful excursion of MV & TV leaflets occurs & true apex is seen. -false tendons of LV & moderator band of RV are normal variants. –crux of heart.

• Apical 5 chamber –tilt the transducer into a shallower angle

- Both AR & MR can be dected .

- Distinguish between subvalvular & valvular AS.

• Apical 2 chamber- rotating the transducer CCW approx 60 deg. Similar orientation to RAO angiographic view LA APPENDAGE IS VIEWED.

• Apical long axis view –transducer rotated CW 60 similar to PLAX. LV walls & ultrasound beam are parallel. Quantifying aortic valvular & subvalvular obstruction including HOCM.

• beam is oriented perpendicular to long axis of LV

• better endocardial definition• septal defects are better delineated.• Only view that visualises superior portion of

IAS• proximity of RV free wallto the

transducer(pericardial tamponade)• IVC & hepatic veins are viewed.

Far Posterior tilt to visualise pulmonary veins

Anterior tilt to image entire length of LVOT

Tilting the plane far anteriorlyLVOT not seenTrabeculated &outflow of RV, pulm valve, part of PA

• Depending on orientation of imaging planeto arch

• PARALLEL- asc & des segments of aorta, origin of innominate, lt cca, lt sca, rpa are viewed.

• PERPENDICULAR- RPA & LA are viewed

• fractional shortening and EF• Fractional shortening—the percentage change in

the LV minor axis in a symmetrically contracting ventricle

• FS(%)= (LVIDd – LVIDs)/LVIDd × 100%• FS = 25% – 45% (normal range)• LV volumes by 2D: 1. Prolate ellipsoid method. 2. Hemi-ellipsoid (bullet) method. 3. Biplane method of discs (modified

Simpson’s)

• LV DIMENSIONS

• SHORT AXIS

diastole 3.5- 6.0

systole 2.1- 4.0

Long axis

diastole 6.3- 10.3

systole 4.6- 8.4

LV volume women men

Diastolic volume, mL

59-138 96-155

Diastolic volume/BSA, mL/m2

61+_ 13 67+_9

Systolic volume, mL

18-65 33-68

Systolic volume/BSA, mL/m2

26+_7 27+_5

• Fractional shortening—the % change in the LV minor axis in a symmetrically contracting ventricle

• FS(%)= (LVIDd – LVIDs)/LVIDd × 100%

• FS = 25% – 45% (normal range)

measure

women

men

Range mild

mod

severe

range

mild mod severe

Linear method

Endocardial FS %

27-45 22-26

17-21

≤16 25-43

20-24

15-19

≤14

2D method

EF% ≥55 45-54

30-44

<30 ≥55 45-54

30-44

<30

• AORTA annulus : 1.4- 2.6 cm at leaflet tips: 2.2- 3.6 asc aorta : 2.1- 3.4LA PLAX : 2.3- 4.5 A4C med-lat : 2.5- 4.5 sup-inf 3.4-6.1MITRAL ANNULUS end diastole: 2.7 +_ 0.4 end systole 2.9+_ 0.3

• RV wall thickness 0.2- 0.5 minor dimension 2.2- 4.4 length diastole 5.5-9.5 systole 4.2-8.1PA annulus 1.0- 2.2 Main PA 0.9- 2.9IVC diametre 1.2- 2.3

• Left ventricular mass (MassLV) = 0.8 × [1.04 (IVS + PWT + LVIDd)3 – LVIDd3] + 0.6 g

women

men

mild Mod Severe

Mild Mod Severe

LV mass

67-162

163-186

187-210

≥211 88-224

225-258

259-292

≥293

LV mass/BSA

43-95

96-108

109-121

≥122 49-115

116-131

132-148

≥149

Septal thickness, cm

.6-.9 .9-1.2

1.3-1.5

≥1.6 .6-.9 .9-1.3

1.4-1.6

≥1.7

PW,cm

.6-.9 .9-1.2

1.3-1.5

≥1.6 .6-.9 .9-1.3

1.4-1.6

≥1.7

THREE DIMENSIONAL ECHOCARDIOGRAPHY

• One of the most significant developments of the last decades was the introduction of 3-dimensional (3D) imaging and its evolution from slow and labor-intense off-line reconstruction to real-time volumetric imaging

• The major proven advantage of this technique is the improvement in the accuracy of the echocardiographic evaluation of cardiac chamber volumes.

• Another benefit of 3D imaging is the realistic and unique comprehensive views of cardiac valves and congenital abnormalities

• The major breakthrough that allowed quality real-time imaging was the development of a microbeam former

• When the entire crystal of the transducer head is sampled or covered with elements, the transducer is a dense array

• The microbeam former is required for this arrangement to provide a communication of all of the approximately 3000 elements to the ultrasound system

• Transducer design

• 2 D Matrix array of transducer elements helps generate the third dimension

• The significant innovation that actually allows steering is making the elements electrically independent from each other

• This allows generating a scan line that varies azimuthally and elevationally

• Modern 2D transducers therefore consist of thousands of electrically active elements that steer a scan line left and right as well as up and down

• Beam forming in three spatial dimensions1. Beam forming constitutes the steering and focusing

of transmitted and received scan lines2. Significant portion of the beam steering is done

within the transducer in highly specialized integrated circuit

3. The main system steers at coarse angles, but the transducer circuits steer in fine increments in a process termed microbeam forming

4. Summing is the act of combining raw acoustic information from each element to generate a scan line and by summing these in a sequence (first in the transducer and then subsequently in the system)

• There are two major black and white modes run in an electronically steered 3D system

• Live mode where the system scans in realtime three dimension

• Gating, this time only four to eight beats, allows a technique to generate wider volumes while maintaining frame rate

• 3 D modes1.Live 3D mode–instantaneous2.3D zoom–instantaneous3.Full-volume–gated4.3D color Doppler–gated

• Display of 3D information1.A 3D data set consists of bricks of pixels

called volume elements or voxels• A process known as cropping can be used

to cut into the volume and make some voxels invisible

• 3D data sets of voxels are turned into 2D images in a process known as volume rendering

• All 3D echocardiography is subject to the laws of physics.

• Artifacts such as ringing, reverberations, shadowing, and attenuation occur in three and two dimensions.

• . The constraints of a 3D image are bounded by:

(1)Frame rate,

(2) 3D volume size,

(3) Image resolution. • Increasing the requirement of one of these causes a

drop in the other two

• 1) Direct evaluation of cardiac chamber volumes without the need for geometric modeling

• 2) Noninvasive realistic views of cardiac valves and congenital abnormalities , helpful for showing a variety of pathologies and assessing the effectiveness of surgical or percutaneous transcatheter interventions

• 3) Direct3D assessment of regional LV wall motion aimed at objective detection of ischemic heart disease at rest and during stress testing ,as well as quantification of systolic asynchrony to guide ventricular resynchronization therapy

• 4) 3D color Doppler imaging with volumetric quantification of regurgitant lesions shunts ,and cardiac output

• 5) Volumetric imaging and quantification of myocardial perfusion

• True myocardial motion occurs in three dimensions, and traditional 2D scanning planes do not capture the entire motion of the heart

• Quantifying implies segmenting structures of interest from the 3D voxel set

• 3D quantification of the left ventricle typically employs a surface- rendered mesh

• This allows accurate computation of volume, regional wall motion, and regional synchrony

• Most studies have been done on mitral valve. Understanding about the mitral valve annulus, leaflet tethering, tenting volumes has improved with the advent of 3 D echocardiography

M-MODE ECHOCARDIOGRPHY

• B mode echoes from an interface that changes position will be seen as echoes moving towards and away from the transducer.

• If a trace line is placed on this interface and the resulting trace is made to drift across the face of a CRT screen a motion pattern is obtained.

• The resulting display shows motion of a reflector over distance and time – a distance time graph

• The change in distance (dy) over a period of time dt is represented by the slope of the reflector line of motion.

• dy/dt = slope = velocity

• If this motion pattern is obtained on moving cardiac structures then the resulting images constitute M-mode echocardiography.

• M-mode echocardiography is use to evaluate the morphology of structures, movement and velocity of cardiac valves and walls and timing of cardiac events.

Distance

Time

• Amplitude

• Velocity

• Time intervals

• Morphology

Amplitude = Y2 –Y1

Y1

Y2

Distance

Time

Time interval = T2 – T1

T2T1

Distance

Time

dy = Y2 –Y1

Y1

Y2

T1 T2

dt = T2 – T1

Slope = dy/dt = velocity

• The mitral valve has 2 leaflets – anterior and posterior.

• Specific letters corresponding to systole and diastole are assigned to the m-mode tracing of the mitral valve.

EKG Tracing

T-wave

QRS complex

P wave

Systole Diastole

Distance

SystoleDiastole

Time

Phase of Cardiac Cycle

Assigned Letters

Diastole d,e,f, and a

Systole c and d

SystoleDiastole

dc

a

f

e

d

Time

Distance

SystoleDiastole

e

d Time

Distanced-e amplitude

SystoleDiastole

Septum

e

Time

DistanceEPSS

Systole

Diastole

e

d Time

Distanced-e slope

SystoleDiastole

f

e

Time

Distancee-f slope

M-mode at the Mitral Valve

Amplitude DescriptionNormal Value

EPSS Measure e point to septal separation

< 5 mm

d-e Measures the maximum excusion of the mitral valve following diastolic opening.

17 to 30 mm

M-mode at the Mitral Valve

Slope Description Normal Value

d-e Measure rate of initial opening of the mitral valve in early diastole.

240 to 380 mm/s

e-f Measures the rate of early closure of the mitral valve following diastolic opening.

50 to 180 mm/s

• Flail PMVL

• Fluttering of the AMVL

• Mitral Stenosis

• LA myxoma

• Vegetations

Distance

SystoleDiastole

Time

B-bump on theAC shoulder.

Distance

SystoleDiastole

Time

Premature Closure

Premature Closure- closureon or before the onset of theQRS complex.

Distance

SystoleDiastole

Time

Systolic anterior motion of the AMVL

Distance

SystoleDiastole

Time

MV prolapse posterior leaflet

Distance

SystoleDiastole

Time

MV Prolapse – both leaflet

Distance

SystoleDiastole

Time

Flail posterior leaflet

Distance

SystoleDiastole

Time

Aortic Regurgitation

Distance

SystoleDiastole

Time

Sinus Rhythm

Mitral Stenosis

Distance

SystoleDiastole

Time

Atrial Fibrillation

Mitral Stenosis

Distance

SystoleDiastole

Time

Atrial Myxoma

Distance

SystoleDiastole

Time

Vegetation

Distance

SystoleDiastole

Time

Distance

SystoleDiastole

Time

• The aortic valve has 3 cusps – right coronary, left coronary and non-coronary cusps.

• The cusps imaged in the PLAX view are the right coronary and the non-coronary cusps.

M-mode at the Aortic Valve

Coronary cusp

Non-coronary cusp

Anterior aortic root

Posterior aortic root

Left Atrium

M-mode at the Aortic Valve

LA dimension

Cusp SeparationAortic root

M-mode at the Aortic Valve

LA dimension

Cusp SeparationAortic root Measurements are made from leading edge to leading edge.

• Dilated LA• Dilated aortic root• Decreased excursion• Premature opening• Premature closing• Exaggerated anterior motion of Aortic

Root

• Reduced anterior motion of Aortic Root• Thickening• Calcification • Vegetations• Bicuspid valve• Prosthetic valve• Aortic Regurgitation

M-mode at the Aortic Valve

Premature Opening

Opening of the AV before the onset of the QRS complex

Seen in Elevated LV-EDP

M-mode at the Aortic Valve

Premature Closure

Closure of the AV before the onset of the T wave Seen in IHSS

M-mode at the Aortic Valve

Bicuspid Valve

Eccentric closure line

Seen when there is a Bicuspid aortic valve

M-mode at the Aortic Valve

Decreased Cusp Separation

Seen in Aortic Stenosis

M-mode at the Aortic Valve

Seen in aortic sclerosis

Thickened, calcified aorticvalve leaflet.

M-mode at the Aortic Valve

Seen in Mitral Stenosis

Reduced anterior motion of aortic root

M-mode at the Aortic Valve

Exaggerated anterior motion of aortic root

Seen in Mitral Regurgitation

Aortic Regurgitation

Aortic Regurgitation

Aortic Regurgitation

LVPW excursion

LVPW max velocity= slope

Post Infarct

Pericardial Effusion

• Thickening of the IVS and LVPW

• Movement of the IVS and LVPW

• IVSd

• IVS excursion

• IVSs

M-mode Measurement

• LVIDd

• LVIDd index

• LVIDs

• LVIDs index

M-mode Measurement

• LVPWd

• LVPW excursion

• LVPW max excursion velocity

• LVPWs

M-mode Measurement

• % IVS thickening

• % LVPW thickening

• IVS/LVPW ratio

M-mode LV Calculation

M-mode LV Calculation

FS = LVIDd – LVIDs LVIDd

M-mode LV Calculation

EF = LVIDd3 – LVIDs3

LVIDd3

M-mode LV Calculation

IVS % thickening = (IVSs – IVSd) x 100 IVSd

 

M-mode LV Calculation

LVPW % thickening = (LVPWs – LVPWd) x 100 LVPWd

 

M-mode LV Calculation

LV Mass = 1.04 {(LVIDd + IVSd + LVPWd)3 – (LVIDd)3} x 0.8 + 0.6g