Left Ventricular Function

Question 1

What is the MPI (myocardial performance index)?

Answer 1

The sum of isovolumic contraction and relaxation times divided by the ejection time

= isovolemic time / ejection time

Isovolemic times = regurgitation time - ejection time

Question 2

Which segments does the LAD supply?

Answer 2

Anterior, anteroseptal, and inferoseptal walls.

Question 3

Which segments does the LCx supply?

Answer 3

Anterolateral and inferolateral walls.

Question 4

Which segments does the RCA supply?

Answer 4

The inferior wall.

Question 5

Fractional shortening equation

Answer 5

FS=(LVEDd-LVESd)/LVEDd

Question 6

General equation for fractional measurements of function

Answer 6

(diastolic-systolic)/diastolic

Question 7

How is FS measured?

Answer 7

Just beyond chordal level of mitral valve perpendicular to the LAX of the LV using M-mode
(TG 2C or TG SAX)

Question 8

What is the normal value for LV fractional shortening?

Answer 8

> 30%

Question 9

Fractional area change (FAC) equation

Answer 9

(EDA-ESA)/EDA

Question 10

Where is LV FAC measured?

Answer 10

TG mid SAX view (INCLUDE the papillary muscles in the area)

Question 11

What is the normal value for LV FAC?

Answer 11

> 50%

Question 12

Ejection Fraction equation

Answer 12

(EDV-ESV)/EDV

Question 13

Stroke volume equation (using area and VTI)

Answer 13

SV = area x stroke distance = LVOT cross sectional area x time velocity integral through the LVOT

Question 14

Normal dP/dt value

Answer 14

~1300 mmHg/sec

Question 15

What is the relationship of dP/dt to preload and afterload?

Answer 15

It is dependent on preload and independent of afterload

Question 16

How is dP/dt calcualted?

Answer 16

How long it takes to increase the pressure from 4mmHg to 36mmHg (1m/sec to 3m/sec in the MR CWD profile). The slope between 1 and 3 m/sec is the dP/dt.

Question 17

What is velocity of circumferential shortening?

Answer 17

Fractional shortening with ejection time in the denominator

VCF=(LVEDd-LVESd)/LVEDd ET

Question 18

Two ways to measure ejection time

Answer 18

1. Use calipers to measure ejection through AV on cWD
2. Use M-mode to determine how long the AV is open

Question 19

What is pulsus alternans?

Answer 19

Alternating strong and weak beats, seen in severe LV dysfunction.

This is not the same as pulsus paradoxus or electrical alternans, seen in tamponade

Question 20

Normal MPI value for the LV

Answer 20

</= 0.4

Question 21

What does MPI measure?

Answer 21

Both systolic and diastolic function

Question 22

Which measures of systolic function are load independent?

Answer 22

• End-systolic elastance
• Preload recruitable stroke work
• Preload adjusted max power
• Strain rate

Question 23

What are the 12 measures of systolic function?

Answer 23

• Qualitative assessment
• Fractional shortening (FS)
• Fractional area change (FAC)
• Ejection fraction (EF)
• Velocity of circumferential shortening (Vef)
• Stroke volume/cardiac output
• Dp/dt
• Tissue doppler peak systolic velocity (S’)
• Strain rate
• End systolic elastance
• Preload recruitable stroke work
• Preload adjusted max power

Question 24

What are the two ways to measure strain rate? Which one is angle independent?

Answer 24

Tissue Doppler or speckle tracking. Speckle tracking is angle independent.