Diastolic Dysfunction

Question 1

What is the isovolumic relaxation time?

Answer 1

Time period between aortic valve closure and mitral valve opening where LV pressure decreases, but volume remains constant

Question 2

What are the 4 phases of LV filling during diastole and what is the physiological basis of each phase?

Answer 2

Isovolumic relaxation time, rapid filling, diastasis, atrial kick. Rapid filling during early diastole is due to LV relaxation and the rate of decline of early diastolic filling is related to LV stiffness. In late diastole, the LA contracts and leads to another positive transmitral P gradient.

Question 3

Which 3 variables can impair LV relaxation (i.e delay and/or slow)?

Answer 3

Increased afterload, asynchrony, inactivation (mechanisms leading to actin-myosin detachment and reduced calcium in the sarcoplasm)

Question 4

What is the time constant tau?

Answer 4

A way of invasively measuring LV relaxation

Question 5

What intrinsic and extrinsic factors affect LV chamber stiffness?

Answer 5

Intrinsic factors: LV geometry and myocardial stiffness. Extrinsic: Pericardium , RV-LV interactions

Question 6

What invasive measurements might support a diagnosis of diastolic heart failure?

Answer 6

PAWP > 12mm Hg, LVEDP > 16mm Hg, Tau > 48msec, LV chamber stiffness constant > 0.27

Question 7

What 5 parameters should be assessed from the mitral inflow for diastolic dysfunction?

Answer 7

E velocity, A velocity, E/A ratio, IVRT, E wave deceleration time

Question 8

How does IVRT change with progressive diastolic dysfunction?

Answer 8

Initially, with only impaired relaxation the IVRT is prolonged since it takes longer for a positive transmitral pressure gradient that can open the mitral valve to develop. As left atrial pressure increases significantly, the IVRT can shorten because a positive transmitral pressure gradient develops earlier.

Question 9

What are the normal values for 1. E/A ratio, 2. IVRT, 3. DT?

Answer 9

1. 0.8-2 2. 70-90msec 3. 150-240msec

Question 10

What factors can cause E/A fusion?

Answer 10

Sinus tachycardia, PAC, 1st degree HB

Think if time between QRS and p wave on ECG

Question 11

Why does E/A fusion affect interpretation of E/A ratio?

Answer 11

The E/A ratio can be reduced compared to values obtained at slower HR since the mitral inflow velocity has less time to decrease before atrial contraction

Question 12

What are the 4 grades of diastolic dysfunction?

Answer 12

Grade 1 = Impaired Relaxation Grade 2 = Pseudonormal Grade 3 = Reversible Restrictive Grade 4 = Irreversible Restrictive

Question 13

What echo parameters can differentiate normal diastolic function from pseudonormal diastology?

Answer 13

Elevated TR V max, increased LA size, reduced e’ velocity, decreased S/D pulmonary vein flow (<1), elevated reversal of flow atrial contaction velocities

Question 14

What are the main waves in the mitral valve tissue doppler annular velocity?

Answer 14

An s wave as the mitral annulus moves towards the LV apex during systole. Two waves as the mitral annulus returns to its initial position during diastole during rapid filling (e’) and atrial contraction (a’)

Question 15

What are normal septal and lateral e’ velocities?

Answer 15

Septal e’ > 10cm/s and lateral e’ > 12cm/s

Question 16

What are the ASE recommendations for interpreting E/e’ velocities?

Answer 16

There are normal, indeterminate and abnormal values. ASE suggests as average E/e’ > 13 is suggestive of elevated filling pressures in patients with normal LVEF

Question 17

In which situations does E/e’ not provide an accurate assessment of PCWP?

Answer 17

1. In the normal heart - e’ behaves as a load-dependent variable
2. Constrictive pericarditis (annulus paradoxus where E/e’ does not increase despite elevated PCWP)
3. In mitral valve disease / mitral valve replacement

Question 18

What is the Tei index and how is it calculated?

Answer 18

Tei index is an overall measure of myocardial performance in both systole and diastole.
MPI = (IVCT + IVRT)/LVET

Question 19

In which grades of diastolic dysfunction are LA pressures usually elevated?

Answer 19

Grade II to IV

Question 20

Once clinical or echocardiographic features of impaired LV relaxation are established, what values of E/A, DT, E/e’, PASP would suggest severely elevated LAP (> 25 mm Hg)

Answer 20

E/A >2, DT < 150msec, E/e’> 20, PASP > 60mm Hg

Question 21

How can LV filling pressures be estimated in patients with AF?

Answer 21

DT < 150msec is accurate in decresed LVEF; septal E/e’> 11, IVRT < 65msec, peak acceleration rate of mitral velocity > 1900cm/sec2, PASP > 35mm Hg, DT of pulmomary vein diastolic velocity < 220msec; reduced beat to beat variation in Doppler measurements (Chp 42)