echo tee and tte

ECHO TEE AND TTE

ECHO (CARDIAC ULTRASOUND)

Echo is something we experience all the time. If we shout into a well, the echo comes back a moment later. The echo occurs because some of the sound waves in our shout reflect off a surface (either the water at the bottom of the well or the wall on the far side) and travel back to our ears. A similar principle applies in cardiac ultrasound.

GENERATION OF AN ULTRASOUND IMAGE

Echocardiography (echo or echocardiogram) is a type of ultrasound test that uses high-pitched sound waves to produce an image of the heart.

The sound waves are sent through a device called a transducer and are reflected off the various structures of the heart. These echoes are converted into pictures of the heart that can be seen on a video monitor.

Transducers, typically made of quartz or titanate ceramic, use crystals that exhibit the piezoelectric effect

PROPERTIES OF ULTRASOUND

WAVELENGTH, AMPLITUDE FREQUENCY PROPAGATION VELOCITY IMAGE RESOLUTION ATTENUATION ACOUSTIC IMPEDENCE GAIN PRF

PROPERTIES OF ULTRASOUND sequence of compression and rarefaction is described by

sine waves characterized in terms of Wavelength distance between two peaks of the sine wave Frequency number of cycles that occur in 1 second Amplitude measure of tissue compression Propagation velocity speed of an ultrasound wave traveling through tissue

Echocardiography uses frequencies of 2.5 to 7.5 million cycles/sec (MHz)

PROPERTIES OF ULTRASOUND Image resolution is characterized in terms of

Axial resolution(along length)

Elevational resolution(thickness of image)

Temporal resolution(ability to accurately locate moving structures at a particular instant in time)

Lateral resolution(increased frequency-less divergence

LATERAL RESOLUTION


Attenuation :- a function of tissue absorption , divergence of ultrasound energy as it moves away from the transducer, reflection, and scattering

PROPERTIES OF ULTRASOUND Acoustic impedance :- refers to the resistance that

an ultrasound wave meets when traveling though tissue

Mismatches in acoustic impedance and attenuation are important to consider in imaging the heart

For example, the upper aortic arch is difficult to visualize from the esophagus


GAIN

-to amplify low amplitude ultrasound waves

reflected back to transducer

PULSE REPETITION FREQUENCY

-no of pulses that leave or are returned back

to transducer in a single second

-image depth increases PRF decreases

THE MODALITIES OF ECHO

The following modalities of echo are used clinically:1. Conventional echo Motion- mode echo (M-mode echo) Two-Dimensional echo (2-D echo) 3-D ECHO

2. Doppler Echo Continuous wave (CW) Doppler

Pulsed wave (PW) DopplerColour flow(CF) Doppler

All modalities follow the same principle of ultrasoundDiffer in how reflected sound waves are collected and

analysed

M-MODE ECHOCARDIOGRAPHY

An M- mode echocardiogram is not a "picture" of the heart, but rather a diagram that shows how the positions of its structures change during the course of the cardiac cycle.

M-mode recordings permit measurement of cardiac dimensions and motion patterns.

Also facilitate analysis of time relationships with other physiological variables such as ECG, and heart sounds.

TWO-DIMENSIONAL ECHO (2-D ECHO)

This technique is used to "see" the actual structures and motion of the heart structures at work.

Ultrasound is transmitted along several scan lines(90-120), over a wide arc(about 900) and many times per second.

The combination of reflected ultrasound signals builds up an image on the display screen.

A 2-D echo view appears cone-shaped on the monitor.

3-D ECHO

The advance from 2D to real-time 3D echocardiography has proved difficult.

The time needed to acquire the requisite 2D images, the computing challenge of collating them into 3D images, and the display challenge of depicting 3D images on a 2D video screen all contributed to the difficulty.

Matrix-array transducers typically, contain over 3000 imaging elements and electronically rotate the 2D ultrasound beam through 180 degrees in milliseconds to acquire the requisite 2D images in a fraction of the time possible with mechanically rotated multiplane transducers.

DOPPLER ECHOCATDIOGRAPHY

DOPPLER SHIFT(CHRISTIAN DOPPLER) The ultrasound that bounces off moving red

blood cells is reflected back to the transducer at a slightly different frequency than that emitted from the transducer. The shift in frequency allows the ultrasound machine to estimate blood flow velocity and direction of flow.

DOPPLER ECHOCARDIOGRAPHYDoppler echocardiography is a method for detecting the direction and velocity of moving blood within the heart.

Pulsed Wave (PW) useful for low velocity flow e.g. MV flow

Continuous Wave (CW) useful for high velocity flow e.g aortic stenosis

Color Flow (CF) Different colors are used to designate the direction of blood flow. red is flow toward, and blue is flow away from the transducer with turbulent flow shown as a mosaic pattern.

Doppler Technique

Advantages Disadvantages Clinical Uses

Pulsed wave

Measures blood flow velocities at selected areas of interest 3-5 mm wide along the ultrasound scan line

Cannot measure fast blood flow velocities (>1 m/sec) because of aliasing

To measure blood flow velocities through the pulmonary veins and mitral valve and in low-flow areas within the heart

Continuous wave

Detects blood flow velocities up to 7 m/sec (not subject to the Nyquist limit)

Cannot identify location of the peak velocity along the ultrasound scan line

To measure blood flow velocities through the aorta, aortic valve, stenotic valve lesions, and regurgitant valvular jets

Color flow Presents the spatial relationships between structure and blood flow

Like pulsed wave Doppler, cannot measure fast blood flow velocities because of aliasing

To enhance recognition of valvular abnormalities, aortic dissections, and intracardiac shunts

One limitation of PWD is that it may be too slow to capture the velocity of fast-moving blood cells. This phenomenon is known as aliasing.

The limit at which the sampling rate fails to accurately capture the true velocity is called the Nyquist limit

Aliasing of PWD occurs at blood flow velocities greater than 0.8 to 1.0 m/sec. Normal flow within the heart may reach 1.4 m/sec and pathologic flow up to 6 m/sec.

TRANSESOPHAGEAL ECHO

REASONS FOR SUCCESS OF TEE

1. Close proximity of esophagus to post wall of heart – no intervening structure like bone or lung

2. Monitor the heart over time, such as during cardiac surgeries

3. Extremely safe & well tolerated so that it can be performed in critically ill patients & very small infants

CATEGORY 1 INDICATIONS FOR TEE

Intraoperative evaluation of acute, persistent, and life-threatening hemodynamic disturbances

Intraoperative use in valve repair Intraoperative use in congenital heart surgery for most lesions

requiring cardiopulmonary bypass Intraoperative use in repair of hypertrophic obstructive

cardiomyopathy Intraoperative use for endocarditis when preoperative testing was

inadequate or extension of infection to perivalvular tissue is suspected

Preoperative use in unstable patients with suspected thoracic aortic aneurysms, dissection, or disruption who need to be evaluated quickly

Intraoperative assessment of aortic valve function during repair of aortic dissections with possible aortic valve involvement

Intraoperative evaluation of pericardial window procedures Use in the intensive care unit for unstable patients with unexplained

hemodynamic disturbances, suspected valve disease

EQUIPMENT DESIGN AND OPERATION

A miniaturized echocardiographic transducer (about 40 mm long, 13 mm wide, and 11 mm thick) mounted on the tip of a gastroscope.

Transducer is with 64 piezoelectric elements operating at 3.7 to 7.5 MHz

Like standard

gastroscopes two

rotary knobs control

the movements

CONTRAINDICATIONS

Absolute

1. Previous esophagectomy,

2. Severe esophageal obstruction,

3. Esophageal perforation, and

4. Ongoing esophageal hemorrhage

CONT.

Relative

1. Esophageal diverticulum,

2. Varices,

3. Fistula, and

4. Previous esophageal surgery, history of gastric surgery, mediastinal irradiation, unexplained swallowing difficulties

PATIENT PREPARATION

Informed consent Pt. should fast for at least 4 – 6 hrs Thorough history should be taken – any

dysphagia i.v. access Pre oxygenation Suction should be available

BASIC TRANSESOPHAGEAL EXAMINATION Patient is anesthetized (topically) The contents of the stomach are suctioned

Patient's neck is then extended and the well-lubricated TEE probe is introduced

If the probe does not pass blindly, a laryngoscope can be used

TRANSESOPHAGEAL ECHOCARDIOGRAPHY

TEE VIEWS

Upper oesophageal (UE) level 20-25cm

Mid Esophageal (ME) level 30-40cm

Trans Gastric (TG) level beyond 40 cm

MIDESOPHAGEAL VIEWS

4 CHAMBER 0 DEGREES

5-CHAMBER 0 DEGREES

5 CHAMBER 0 DEGREES

2 CHAMBER 90 DEGREES

LONG AXIS 120-140 DEGREES

SHORT AXIS 30-60 DEGREES

BICAVAL 90-110 DEGREES

TRANSGASTRIC VIEWS MOST IMPORTANT TRANSESOPHAGEAL VIEWS BEST FOR EVALUATING LEFT AND RIGHT VENTRICULAR FUNCTION COMMONLY EMPLOYED INTRA OPERATIVE TEE TO ASSESS EJECTION FRACTION AND WALL MOTION POST-OPERATIVELYDEEP TRANSGASTRIC VIEWS ARE THE BEST VIEWS TO OBTAIN ACCURATE GRADIENTS ACROSS THE AORTIC VALVE TO ASSESS THE DEGREE OF AS OR AR

TRNSGASTRIC SHORT AXIS

TRANSGASTRIC SHORT AXIS 0 DEGREES

TRANSGASTRIC SHORT AXIS 0 DEGREESAT PAPILLARY MUSCLE LEVEL

TRANSGASTRIC SHORT AXIS 0 DEGREESMITRAL VALVE LEVEL

TRANSGASTRIC SHORT AXIS 0-30 DEGREESAT TRICUSPID VALVE LEVEL

TRANSGASTRIC SHORT AXIS 30-60 DEGREESAT RVOT

TRANSGASTRIC LONG AXIS 90 DEGREES LV

TRANSGASTRIC LONG AXIS 90 DEGREESMITRAL VALVE

TRANSGASTRIC LONG AXIS 90 DEGREES LV

TRANSGASTRIC LONG AXIS 110-130 DEGREESLVOT AND AORTIC VALVE

DEEP TRANSGASTRIC 0 DEGRES

HIGH ESOPHAGEAL

HIGH ESOPHAGEAL VIEWS ARE HELPFUL FOR EVALUATING THE GREAT VESSELS INCLUDING THE AORTIC ROOT AND CORONARY ARTERIES, ASCENDING AORTA AND THE PULMONARY ARTERY. A USEFULL LANDMARK IS THE MID-ESOPHAGEAL VIEW OF THE AORTIC VALVE IN SHORT AXIS AT 40-60 DEGREES. BY WITHDRAWING FROM THE LEVEL OF THE AORTIC VALVE, THE ORIGIN OF THE CORONARY ARTERIES CAN BE VISUALIZED

TRANSTHORACIC ECHO

A standard echocardiogram is also known as a transthoracic echocardiogram (TTE), or cardiac ultrasound.

The subject is asked to lie in the semi recumbent position on his or her left side with the head elevated.

The left arm is tucked under the head and the right arm lies along the right side of the body

Standard positions on the chest wall are used for placement of the transducer called “echo windows”

PARASTERNAL LONG-AXIS VIEW (PLAX)

Transducer position: left sternal edge; 2nd – 4th intercostal space

Marker dot direction: points towards right shoulder

Most echo studies begin with this view

It sets the stage for subsequent echo views

Many structures seen from this view

PARASTERNAL SHORT AXIS VIEW (PSAX)

Transducer position: left sternal edge; 2nd – 4th intercostal space

Marker dot direction: points towards left shoulder(900 clockwise from PLAX view)

By tilting transducer on an axis between the left hip and right shoulder, short axis views are obtained at different levels, from the aorta to the LV apex.

Many structures seen

PAPILLARY MUSCLE (PM)LEVEL

PSAX at the level of the papillary muscles are used usually for the purposes of describing abnormal LV wall motion

LV wall thickness can also be assessed

APICAL 4-CHAMBER VIEW (AP4CH)Transducer position: apex of heart

Marker dot direction: points towards left shoulder

The AP5CH view is obtained from this view by slight anterior angulation of the transducer towards the chest wall. The LVOT can then be visualised

APICAL 2-CHAMBER VIEW (AP2CH)

Transducer position: apex of the heart

Marker dot direction: points towards left side of neck (450 anticlockwise from AP4CH view)

Good for assessment of

LV anterior wall

LV inferior wall

SUB–COSTAL 4 CHAMBER VIEW(SC4CH)

Transducer position: under the xiphisternum

Marker dot position: points towards left shoulder

The subject lies supine with head slightly low (no pillow). With feet on the bed, the knees are slightly elevated

Better images are obtained with the abdomen relaxed and during inspiration

Interatrial septum, pericardial effusion, abdominal aorta are seen

SUPRASTERNAL VIEW

Transducer position: suprasternal notch

Marker dot direction: points towards left jaw

The subject lies supine with the neck hyperextended. The head is rotated slightly towards the left

The position of arms or legs and the phase of respiration have no bearing on this echo window

Arch of aorta is seen

ASSESSMENT OF HEMODYNAMICS

1.Evaluation of Ventricular Filling

-measurement of EDA

-LV filling pressure 2.Estimation of Cardiac Output

- measuring both the velocity and the cross-sectional area of blood flow at appropriate locations in the heart or great vessels gives stroke volume

CONT. 3.Assessment of Ventricular Systolic

Function

Fractional area change (FAC) during systole

is a commonly used measure of global LV

function.

FAC = (EDA - ESA)/EDA

CONT. 4.Assessment of Ventricular Diastolic

Function

-E/A ratio

-E wave (higher-velocity component across mitral valve generated by atrial pressure and ventricular relaxation in early diastole)

-A wave(second lower-velocitycomponent generated by atrial contraction in late diastole)

ASSESSMENT OF VENTRICULAR DIASTOLIC FUNCTION

5.DETECTION OF MYOCARDIAL ISCHEMIA Within seconds after the onset of myocardial

ischemia, affected segments of the heart cease contracting normally

New intraoperative segmental wall motion abnormalities (SWMAs) diagnostic of myocardial ischemia

Not all SWMAs are indicative of myocardial ischemia(myocardial stunning,severe hypovolemia)

6.VALVULAR PATHOLOGIES

MS

-ME 4 chamber, 2 chamber LAX

-in 2 D ECHO appears as thickened dome

towards LV

-color flow doppler shows turbulent jet flow into LV

MR

-similar views as for MS

GRADING FOR MITRAL REGURGITATION

Jet Width at Origin (mm)

Jet Area (% LAa) Jet Depth (% LAd)

MILD >2 <25 <50

MODERATE 3-5 25-50 50-90

SEVERE >5 <50 >100

VALVULAR PATHOLOGIES

AS

-ME AV SAX shows thickening of aortic leaflets

-Deep TG LAX with CWD estimates pressure gradient across the AV

AR

-ME AV LAX

- With color Doppler positioned over the leaflets and outflow tract, aortic regurgitation is recognized as a color jet emanating from the valve during diastole

GRADING FOR AORTIC INSUFFICIENCY

Jet Width at Origin (mm)

Jet Area (% LVOT) Jet Depth into the LV (cm)

MILD <2 <33 1-2

MODERATE 3-5 <66 3-5

SEVERE >5 100 >5

7. STRESS ECHO

New regional wall motion abnormalities, a decline in ejection fraction, and an increase in end-systolic volume with stress are all indicators of myocardial ischemia. Exercise stress testing is usually done with exercise protocols using either upright treadmill or bicycle exercise. Pharmacologic testing can also be performed by infusion of dobutamine to increase myocardial oxygen demand. Dobutamine echocardiography has also been used to assess myocardial viability in patients with poor systolic function and concomitant CAD.

It determine the hemodynamic response to stress, In patients with low-output, low-gradient aortic stenosis

UNDERSTANDING ECHO REPORT

LEFT VENTRICLE

WALLS IVS(d) 0.6-1.1 cm

IVS(s) 0.8-2.0 cm

PW(d) 0.6-1.1 cm

PW(s) 0.8-2.0 cm

CHAMBERS

LVID(d) 3.7-5.6 cm

LVID(s) 1.8-4.2 cm

RWT <0.42 cm

SYSTOLIC FUNCTION

FS 34-44%

EF >50%

MASS LVMI 50-95 g/m2

women men

RANGE MILD MODER

ATESEVERE

RANGE MILD MODERATE

SEVERE

EF(%)

>55 45-54 30-44 <30 >55 45-50 30-44 <30

UNDERSTANDING ECHO REPORT

RIGHT VENTRICLE

RVD (at base) 2.6-4.3 cm LEFT ATRIUM

LAD(anteroposterior) 2.3-3.8 cm

LAV ( ml/m2) 16-28 Aortic root dimension (cm) 2.0–3.5 Aortic cusps separation (cm) 1.5–2.6 Pulmonary AA dia 1.5-2.1 cm(mild 2.2-2.5,moderate 2.6-2.9,

severe >3 cm) Mitral flow (m/s) 0.6–1.3 Tricuspid flow (m/s) 0.3–0.7 Aorta (m/s) 1.0–1.7 Pulmonary artery (m/s) 0.6–0.9

CONCLUSION

Echocardiography provides a substantial amount of structural and functional information about the heart.

Still frames provide anatomical detail.

Dynamic images tell us about physiological function

The quality of an echo is highly operator dependent and proportional to experience and skill, therefore the value of information derived depends heavily on operation and interpretation

echo tee and tte

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