CTSN - Echocardiography

Echocardiography

Go to the Digital Echocardiography Library

View the TSDA Transesophageal Echocardiography Review

View TSDA Curriculum Online for this topic

1. High frequency ultrasound = 2.0 - 7.5 MHz

Adults = 2.0 - 2.5 MHz
Pediatric = 3.0 - 5.0 MHz
TEE = 3.5 - 7.5 MHz

M-mode "ice pick view"
2D sector scanning
Doppler effect
Color flow imaging

2. Standard Transducer Position

Transthoracic - long and 90^o short axis

Parasternal - long and short

Apical

Subcostal - 4 chamber and ventricular septum

Suprasternal

Transesophageal

I. Basal short axis
II. Four chamber
III. Transgastric

3. Doppler Effect

Sound frequency increases as sound source moves toward observer; frequency decreases as source moves away.
Ultrasound of known frequency is transmitted to heart or blood vessel.
Moving RBC's reflect ultrasound waves at altered frequency depending on direction RBC's are moving.
Frequency shift is used to estimate blood flow velocity.

4. Color Flow Imaging

Doppler flow velocity sampled at multiple sites (gates)
Frequency shift converted to color scheme

   Blood flow toward transducer = RED
   Blood flow away    = BLUE
   Turbulence (multiple directions) = GREEN
   High frequency   = WRAP AROUND OR ALIASING

5. Hemodynamic Assessment by Doppler

Doppler shift measures blood flow velocity
Flow velocity converted to pressure gradient by Bernoulli equation

DP = 4 x (V₂)²

Sum of flow velocity during ejection period = time velocity integral (TVI)

Used with cross sectional area to calculate flow

Valve area

Continuity equation
Pressure half-time

Flow velocity across a regurgitant valve is related to intracardiac pressure

6. Typical 2D ECHO Patterns

Normal Anatomy

Four Chamber
-[RealVideo clip]-

Normal Valve Anatomy