Cardiac imaging Planes

  • ECHO imaging planes are defined in relation to the position of the heart not the anatomical planes of the body

  • heart axis is rotated in relation to the body axis (not the mean QRS axis)

Transducer

  • small footprint transducer (eg. phased array or microconvex-array) is desired to obtain images in between and around ribs

  • lower frequency allows better penetration (2-5 MHz) because takes longer for attenuation to occur

  • curvilinear probe may be used but only in the subxiphoid or subcostal position

  • selecting the cardiac modality on the point-of-care ultrasound machine will optimize image acquisition; note that the probe indicator marker is now to the right of the ultrasound screen

Transducer Movements

  • moving

    • sliding

      • probe moves parrallel to indicator​

    • sweeping

      • probe moves perpendicular to indicator​

  • rocking (heel-toeing)

    • rocking the probe parrallel to the indicator​

  • tilting (fanning)

    • rocking the probe perpendicular ​to indicator

  • rotating

    • turing the probe clockwise or counterclockwise​

  • compression

    • applying axial pressure along the long axis of the transducer​

Transducer pointer

  • as long as the indicator on the screen and probe are on the same side, your image should be anatomically correct 

  • historically, cardiologist established the probe indicator to be placed on the right side of the screen from the viewer's presepective

Windows and Views

  • parasternal long-axis

  • parasternal short-axis (mid-ventricle)

  • parasternal short axis (base)

  • apical four-chamber

  • subcostal

Parasternal Long-Axis View

  • 3rd to 5th intercostal space

  • 30 to 45 degrees toward left lateral

  • assessment of left ventricular systolic function

  • view aortic and mitral valve

  • assessment of pericardial effusion

  • not suited for right ventricle size evaluation because it varies greatly

Parasternal Short-Axis View: mid ventricular view

  • 30 to 45 degree left lateral decubitus​

  • assessment of left ventricular size and function

  • assessment of right ventricular size and function

  • assessment of pericardial effusion

Parasternal Short-Axis View: Base

  • tilt the back of the transducer toward the patients left hip

  • assessment of aortic valve morphology and function

  • assessment left atrial size & interatrial septum

  • assessment of tricuspid and pulmonic valve morphology and function

Apical Four-Chamber View

  • 30-45 degree left lateral decubitus

  • near apical impulse

  • point the probe toward the patients back

  • tricuspid annulus is closer to the apex than the mitral valve annulus

  • Assess left ventricular size and function

  • Assess right ventricular size and function

  • Assess tricuspid and mitral valve morphology and function

  • Assess right and left atrial size

Subcostal Four-Chamber View

  • supine and bend knees; deeper breathing helps

  • transducer indicator pointing toward left flank and the US beam aimed toward left shoulder

  • compression is often required

  • Assess right and left ventricular systolic function

  • Assess interatrial septum

  • Assess pericardial effusion

IVC Evaluation

  • use low frequency transducer (eg. curved or phased array)

  • starting from subcostal view, rotate counterclockwise and tilted perpendicular to the long axis of the body

  • right atrial pressure determined by the degree of collapse of the IVC upon inspiration (more predictive than diameter alone)

  • diameter measured at the junction of hepatic veins draining into IVC

Dilated Right Ventricle

  • pulmonary embolism

  • ASD

  • VSD

  • tricuspid regurgitation

  • pulmonary regurgitation

  • pulmonary hypertension

Interventricular flattening timing and right heart disease (volume vs pressure overload)

  • systolic flattening

    • pulmonary HTN​

  • diastolic flattening

    • volume overload​

RV volume overload (hyperdynamic & dilated):

  • ASD

  • tricuspid regurgitation

  • pulmonary regurgitation

Acute Pulmonary Embolism

  • McConnell's sign (hypokinesis RV base with preserved hyperdynamic contraction of apex) suggests acute pressure overload

  • "D" shaped ventricle

Pericardial Effusion

  • swinging heart, usually circumferential

  • hyperdymanic

  • early diastolic collapse of right ventricular free wall

  • IVC dilated and does not collapse 

  • epicardial fat pad

    • usually only found anteriorly​

    • heterechoic appearance

    • usualy < 1cm

    • to and from movement in concert with cardiac contractions

Cardiac Tamponade 

  • dilation of intrahepatic IVC (most sensitive)

  • early diastolic collapse (highly specific) of right or left ventricle

  • mitral inflow velocity during pulse Doppler > 25% decline during inspiration (pulses paradoxus) or exaggerated drop in systolic blood pressure during inspiration

Left Ventricular Ejection Fraction Estimation

  • normal 55-70%

  • SV = EDV - ESV

  • EF = Stroke volume / EDV

  • Simpson's rule calculator with automated border detection to aid in estimating the ejection fraction

Pleural Effusion

  • parasternal long axis 

    • coronary sinus​ (intra-cardiac)

    • descending aorta (extra-cardiac)

Right Ventricle Dimensions

  • best estimated at end-diastole

  • use a right-ventrcle focused apical 4 chamber view

  • make sure the crux and the apex are in view

  • >42 mm at the base and >35 mm at mid level indicates RV dilatation

  • >86 mm longitudinal indicates RV dilatation

RV Systolic Function

  • evaluated using several parameters

    • TAPSE (tricuspid annular plane systolic excursion)

      • measures RV longitudinal function

      • <16 mm indicates RV systolic dysfunction

      • place M-mode cursor through the tricuspid annulus and measure the amount of longitudinal motion of the annulus at peak systole

... but I would more especially commend the clinician who, in acute diseases, by which the bulk of mankind are cutoff, conducts the treatment better than others.
 
Hippocrates, 400 BC