Echocardiography

Echocardiography

1. High frequency ultrasound = 2.0 - 7.5 MHz
A. Adults = 2.0 - 2.5 MHz
B. Pediatric = 3.0 - 5.0 MHz
C. TEE = 3.5 - 7.5 MHz
D. M-mode "ice pick view"
E. 2D sector scanning
F. Doppler effect
G. Color flow imaging

2. Standard Transducer Positions
A. Transthoracic long
B. Transthoracic 90o short axis
C. Parasternal long
D. Parasternal short
E. Apical
F. Subcostal 4 chamber
G. Subcostal ventricular septum
H. Suprasternal
I. Transesophageal

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

4. Color Flow Imaging
A. Doppler flow velocity sampled at multiple sites (gates)
B. Frequency shift converted to color scheme
1) Blood flow toward transducer = RED
2) Blood flow away = BLUE
3) Turbulence (multiple directions) = GREEN
4) High frequency = WRAP AROUND OR ALIASING

5. Hemodynamic Assessment by Doppler
A. Doppler shift measures blood flow velocity
B. Flow velocity converted to pressure gradient by Bernoulli equation
1) DP = 4 x (V2)2
C. Sum of flow velocity during ejection period = time velocity integral (TVI)
1) Used with cross sectional area to calculate flow
D. Valve area
1) Continuity equation
2) Pressure half-time
E. Flow velocity across a regurgitant valve is related to intracardiac pressure

6. Typical 2D ECHO Patterns
A. Normal Anatomy
1) Four Chamber (RealVideo clip)
B. Normal Valve Anatomy
1) Tricuspid (RealVideo clip)
2) Mitral (RealVideo clip)
3) Aortic (RealVideo clip)
C. Pathologic variations
1) Valvular congenital aortic stenosis
2) Subvalvular congenital aortic stenosis (RealVideo clip)
3) Ebstein's Anomaly
4) Tricuspid atresia
5) Atrial septal defect
6) Ventricular septal defect (RealVideo clip)
7) Cor triatriatum
8) Total anomalous pulmonary venous connection
9) Hypoplastic left heart syndrome
10) Single ventricle
11) Transposition of great arteries
12) Aortic endocarditis (RealVideo clip)
13) Mitral endocarditis (RealVideo clip)
14) Hypertrophic obstructive cardiomyopathy (RealVideo clip)
15) Myxoma (RealVideo clip)
16) Aortic dissection
17) Coarctation
18) Congenital mitral stenosis (RealVideo clip)
19) Congenital rheumatic mitral disease (RealVideo clip)
20) Ruptured mitral chordae (RealVideo clip)

7. Intraoperative
A. Ensure optimal result of reconstructive cardiac surgery
1) Cardiac valve
2) Congenital defect repair
B. Minimize CV complications during operation
1) Air embolism
2) Cardiac wall motion (value controversial)
C. Trouble-shooting the hemodynamically unstable patient