Echocardiogram

Echocardiography

• Def:
  • most frequently used and initial imaging test to evaluate all cardiovascular disease related to a structural, functional, or hemodynamic abnormality of the heart or great vessels

Types

• transthoracic echo
  
• transesophageal echo
  
• stress echo

Structural indications

• pericardium
  
• left or right vent and cavities
  
• valves
  
• great vessels: aortic dissection
  
• atria and septa between cardiac chambers

Hemodynamic indications

• blood flow through valves and cardiac chambers.
  
• includes cardiac output calculation

Doppler

• color flow imaging provides a reliable assessment of cardiac hemodynamics and blood flow

Types of Doppler

• 1. Pulsed wave doppler
  • much more specific but cant give high speeds) Very good spatial resolution
  • (Heisenberg’s uncertainty theory you can know either the speed or position of a particle but not both)
    
  • A Doppler device or procedure that uses pulsed-wave ultrasound.
    
    • – Brief pulses of sound, followed by periods of waiting utilized to detect Doppler shift
      
    • – One element in transducer – both sends and receives sound
• 2. Continuous wave doppler
  • allows to measure higher velocity’s but don’t exactly know where its coming from
    
  • continuous sound 100% of the time.
• 3. Color doppler
  • encoding ever pixel in the box for speed and direction (halfway between both the 2 above)
  • An enhanced form of Doppler echocardiography; different colors are used to designate the direction of blood flow

Echocardiography views

• parasternal long-axis
  
• parasternal short-axis
  
• apical view
  
• -4 or 5 chamber views (aortic valve here)
  
• suprasternal view
  
• subcostal

Parasternal long-axis view

Parasternal short-axis view

• Phase-array transducer view:
  • rotate transducer 90 degrees clockwise.
    
  • plane runs between the left axilla and right costal arch.
• Assess: 
  • best view of aorta and it’s leaflets
    
  • atrial septum and its defects
    
  • tricuspid and pulmonary valves
    
  • pulmonary artery
• Short-axis with caudal tilting:
  • a cross-sectional view of mitral valve
• Short-axis with further caudal tilting:
  • a cross-sectional view of papillary muscles
    
  • evaluates contractility of the central left ventricular segments

Apical view

• View:
  • both ventricles and atria can be visualized from the apex of the heart
• Assess:
  • right and left heart size and function
    
  • tricuspid valve
    
  • mitral valve

5 chamber apical view

• View:
  • Assess the aortic valve
  • A “five” chamber view involves tilting the image plane superiorly to show the base of the aortic valve and the left ventricular outflow tract.

Doppler Effect

• About:
  • describes the change in frequency of a moving source of sound.
  • the sound of an approaching ambulance is perceived to be higher pitched than the sound driving away.
• Velocity:
  • can be calculated based on the frequency of shift
• Function:
  • it is possible to image blood flow not only in terms of velocity but also in terms of direction
• Red:
  • blood flowing toward the transducer
• Blue:
  • blood is flowing away from the transducer
• Yellow-white:
  • velocities usually greater than 1m/s.
    
  • the direction is not differentiated

Cardiac Disease

Valve Disease

• Indication:
  • jet velocity
    
  • mean gradient
    
  • valve area
    
  • valve area index

Left Ventricular Hypertrophy

• Measure:
  • LVPW diastole < 11mm
    
  • mild > 11-13mm
    
  • moderate > 14-16mm
    
  • severe > 17mm

Hypertrophic Cardiomyopathy

Innocent Murmurs

• When the flow in the heart exceeds 1m/s
• i.e in situations where INC. CO requires
  
  • – exercise
    
  • – Pregnancy (CO= 8L/min by wk8
    
  • – anaemia
    
  • – thyrotoxicosis
    
  • – children