Diastolic Dysfunction Flashcards
What is the isovolumic relaxation time?
Time period between aortic valve closure and mitral valve opening where LV pressure decreases, but volume remains constant
What are the 4 phases of LV filling during diastole and what is the physiological basis of each phase?
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.
Which 3 variables can impair LV relaxation (i.e delay and/or slow)?
Increased afterload, asynchrony, inactivation (mechanisms leading to actin-myosin detachment and reduced calcium in the sarcoplasm)
What is the time constant tau?
A way of invasively measuring LV relaxation
What intrinsic and extrinsic factors affect LV chamber stiffness?
Intrinsic factors: LV geometry and myocardial stiffness. Extrinsic: Pericardium , RV-LV interactions
What invasive measurements might support a diagnosis of diastolic heart failure?
PAWP > 12mm Hg, LVEDP > 16mm Hg, Tau > 48msec, LV chamber stiffness constant > 0.27
What 5 parameters should be assessed from the mitral inflow for diastolic dysfunction?
E velocity, A velocity, E/A ratio, IVRT, E wave deceleration time
How does IVRT change with progressive diastolic dysfunction?
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.
What are the normal values for 1. E/A ratio, 2. IVRT, 3. DT?
- 0.8-2 2. 70-90msec 3. 150-240msec
What factors can cause E/A fusion?
Sinus tachycardia, PAC, 1st degree HB
Think if time between QRS and p wave on ECG
Why does E/A fusion affect interpretation of E/A ratio?
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
What are the 4 grades of diastolic dysfunction?
Grade 1 = Impaired Relaxation Grade 2 = Pseudonormal Grade 3 = Reversible Restrictive Grade 4 = Irreversible Restrictive
What echo parameters can differentiate normal diastolic function from pseudonormal diastology?
Elevated TR V max, increased LA size, reduced e’ velocity, decreased S/D pulmonary vein flow (<1), elevated reversal of flow atrial contaction velocities
What are the main waves in the mitral valve tissue doppler annular velocity?
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’)
What are normal septal and lateral e’ velocities?
Septal e’ > 10cm/s and lateral e’ > 12cm/s
What are the ASE recommendations for interpreting E/e’ velocities?
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
In which situations does E/e’ not provide an accurate assessment of PCWP?
- In the normal heart - e’ behaves as a load-dependent variable
- Constrictive pericarditis (annulus paradoxus where E/e’ does not increase despite elevated PCWP)
- In mitral valve disease / mitral valve replacement
What is the Tei index and how is it calculated?
Tei index is an overall measure of myocardial performance in both systole and diastole.
MPI = (IVCT + IVRT)/LVET
In which grades of diastolic dysfunction are LA pressures usually elevated?
Grade II to IV
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)
E/A >2, DT < 150msec, E/e’> 20, PASP > 60mm Hg
How can LV filling pressures be estimated in patients with AF?
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)
