Download Diastology: What the Radiologist Needs to Know. Objectives LV

Objectives
Diastology: What the Radiologist
Needs to Know.
Jacobo Kirsch, MD
Cardiopulmonary Imaging, Section Head
Division of Radiology
Cleveland Clinic Florida
Weston, FL
• To review the physiology and clinical importance of
diastolic function.
• To briefly overview the physiology and echocardiographic
patterns of diastolic dysfunction.
• To review the current literature on assessment of diastolic
function using MRI.
LV Diastolic Function: Introduction
LV Diastolic Function: Introduction
• The ability of the ventricle to fill at low (normal) left atrial
pressure.
• Frequency increases with age
– Up to 50% of patients over 70
– At rest and with exercise.
• Of equal importance to systolic function.
• Energy-dependent process
– Susceptible to disruption by various pathologies.
– More energy-dependent than contraction, therefore:
• More likely to precede systolic dysfunction.
LV Diastolic Function: Introduction
LV Diastolic Function: Introduction
• Primary Myocardial
• Clinically indistinguishable from systolic heart failure.
• ACC/AHA Guidelines (2001):
– Dilated, Restrictive, HOCM
• Secondary Hypertrophy
– Hypertension, AS, AI or MI, Congenital
• CAD
– Ischemia, Infarct
– The diagnosis of diastolic HF is generally based on the finding
of typical symptoms and signs of HF in a patient who is shown
to have a normal left ventricular ejection fraction and no
valvular abnormalities on echocardiography.
• Extrinsic
– Tamponade, constriction
1
LV Diastolic Function: Introduction
LV Diastolic Function: Introduction
• Patients with diastolic heart failure:
• Congestive symptoms result from:
– Not capable of distending a stiff LV.
– Capable of distending a poorly compliant LV with elevated filling
pressures.
– Pulmonary congestion
– Left atrial enlargement and arrhythmia
– Reduced cardiac capacity for exercise
LV Diastolic Function: Hemodynamics
• Patients with diastolic dysfunction are also at increased
risk of future cardiac events.
• When present in combination of systolic failure, it is a
predictor of mortality.
• Additionally, the degree of diastolic dysfunction may
explain the clinical difference in patients with similar EF.
• The effect of impaired diastolic function is reflected on the
LV pressure-volume loop.
Pressure (mmHg)
LV Diastolic Function: Introduction
Volume (ml)
LV Diastolic Function: Hemodynamics
LV Diastolic Function: Hemodynamics
• LV compliance
Ventricular relaxation is divided in four phases:
• Isovolumic relaxation
– Myocardial compliance (intrinsic factor)
– External factors
• Pericardium
• Right Ventricle
• Blood volume
• Intra-thoracic pressure
– From aortic closure to LV pressure falling below LA pressure
70-80%
– From mitral valve opening to LV equaling LA pressure
• Early LV filling
• Diastasis
– Equal pressures, no LV filling occurs
20-70%
– Transmitral pressure gradient is re-established
• Atrial contraction
2
LV Diastolic Function: Hemodynamics
LV Diastolic Function: Hemodynamics
• Early LV filling
• Abnormal relaxation will result in prolongation of the isovolumic
relaxation time, a slower rate of decline in LV pressure, and a
consequent reduction in early filling.
– The predominant factors that affect early filling are
• Rate of LV relaxation
• Elastic Recoil
• LA pressure
– Due to a smaller pressure difference between the LA and LV.
LV Diastolic Function Assessment
LV Diastolic Function Assessment
• For a given LA pressure, slower LV relaxation results in a
later MV opening, reduced early diastolic transmitral
gradient, and a compensatory increase in the proportion
of filling at atrial contraction.
• Direct measurements of LV volume or pressure are
impractical and usually only used for experimental studies.
• A more practical way of assessing LV relaxation is by
measuring the transmitral pressure gradients.
LV Diastolic Function Assessment
LV Diastolic Function Assessment
• In recent years, non-invasive assessment of diastolic
function by transthoracic Doppler echocardiography has
become the most practical and clinically reliable modality
used in the evaluation of diastolic function.
• A sample volume is placed
between the mitral leaflets
and Doppler tracings are
obtained.
3
LV Diastolic Function Assessment
LV Diastolic Function Assessment
• Several parameters which reflect the diastolic function may
be obtained by analyzing the Doppler velocity tracing of
blood flow through the mitral valve:
• early and late (E and A)
diastolic flow velocities.
• the ratio between them (E/A)
• the deceleration time
• the isovolumic relaxation time
–
–
–
–
early and late (E and A) diastolic flow velocities
the ratio between them (E/A)
the deceleration time
the isovolumic relaxation time
E
Em
A
Am
LV Diastolic Function Assessment
Filling Patterns
• Three patterns of diastolic filling
(transmitral flow) are usually
recognized:
• The normal filling pattern shows a large E wave, representing most
of the filling volume, and a small A wave.
• The deceleration time is short.
E
A
– Normal
– Delayed Relaxation
– Restrictive
– Additionally, in patients with a normal
appearing mitral flow but underlying
abnormal diastolic function, a
‘Pseudonormal’ pattern is described.
Impaired Relaxation
200 ms
Em
1.0
m/s
0.0
Am
m/s
0.5
0.0
Young
E
IVRT
S
Normal
Mild
Middle Age
Older
• Patients with delayed relaxation have:
200 ms
m/s
0.5
0.0
Young
E
IVRT
Normal
Mild
Middle Age
Older
Severe
Mild
Moderate
– Reduced filling in early diastole (impaired LV relaxation)
– Normal LA pressure
E
E
A
A
Severe
A
Normal
S
Severe
AR
• However, even in normal patients, ventricular compliance will
change over time with age, therefore changing this normal pattern
with the proportion of LV filling in early diastole (E) decreasing as
age advances.
• The opposite occurs to the atrial contraction (A).
1.0
m/s
0.0
Moderate
D
Filling Patterns
Decrease in LV
Compliance
Mild
A
Filling Patterns
Impaired Relaxation
Decrease in LV
Compliance
Severe
Delayed Relaxation
D
AR
4
Filling Patterns
Filling Patterns
• Patients with a pseudonormal pattern have:
• A restrictive LV filling pattern:
– Apparently normal transmitral flow
– Moderate decrease in LV compliance with compensatory increase in LA
pressure
E
E
E
A
– Severe decrease in LV compliance
– Significantly elevated LA pressures
A
E
E
A
Normal
E
A
A
A
A
Delayed Relaxation
Pseudonormal
Normal
Filling Patterns
E
Delayed Relaxation
Pseudonormal
Restrictive
Diastology for the Radiologist
• To differentiate between the
normal and pseudonormal
patterns, the mitral annulus
velocity (E’) is a useful
parameter.
E
• What is the relevance?
A
– MRI is considered the gold standard in the evaluation of left
ventricular volumes and systolic function.
– Commonly used and fairly available nowadays.
– Newer sequences make it a robust modality for measuring flow.
E
A
A’
E’
E’
A’
What can we find in the literature
What can we find in the literature
Author
Author
Year
Type of
disease
Number of
Patients
Findings
Helbing, et al.
J Am Coll
Cardiol 1996
Fallot
19
Restrictive flow is associated with decreased
exercise.
Paelinck, et al.
Am Heart J
2005
HTN
18
Combining early mitral velocity (E) and early diastolic
septal velocities allowed similar estimation of filling
pressures by MR and Doppler in good agreement with
invasive measurement.
Rathi, et al.
J CardioVasc
MT 2008
Prior
evidence of
diastolic
dysfunction
31
Good agreement between MR and TTE evaluation
of Diastolic function.
Rubinshtein, et al.
AJC 2009
Cardiac
Amyloidosis
38
Moderate good correlation with echo and identified
most patients with restrictive patterns.
Year
Type of
disease
Number of
Patients
Findings
Mohiaddin, et al.
JCAT 1991
Normal and
stenotic MV
15
Proved the technique to have good correlation with
echo.
Hartiala, et al.
Am Heart J
1994
AS
19
Volumetric mitral flow correlates with Doppler.
Can also be used for quantitative measurement of
the volume of blood flow across the mitral valve.
Karwatowski, et al.
J Magn Reson
Imag 1995
Previous MI
11
Early diastolic filing velocities correlate with Doppler
Karwatowski, et al.
Eur Heart J
1996
CAD
25
Early diastolic long axis myocardial velocity has a
significant effect on left ventricular filling.
5