The Left Ventricle Flashcards
Define: Pump Performance
The ability of the ventricle to deliver a stroke volume
Define: Ventricular Function
LV performance relative to the end diastolic fiber length at end diastole
Define: Myocardial Contractility
Property of the myocardial tissue in its active state / its ability to contract
Define: Contractile Function
Ventricular performance affected by load, fiber length, inotropic state
What are the indirect M-mode markers for LV function?
- AO root motion
- Mitral Valve D to E excursion
- Septal and Posterior Wall motion
- B bump
- LAE
- Dilated LV
- Pulmonary Hypertension
What does decreased AO root motion affect?
The propagation of stroke volume
What does a decreased mitral valve excursion mean?
There is a poor stroke volume.
Decreased flow = Decreased pressure = Decreased valve excursion
What does a B bump in a mitral valve M-mode mean?
It indicates an increased LVEDP (LV End Diastolic Pressure).
What is a B bump?
A notch in between the A point and C point on a mitral Valve M-mode
How is pulmonary hypertension indicated on an M-mode?
On a Pulmonic Valve M-mode, the valve closes mid-systole due to abnormal pressures causing a “Flying W”
Myocardial Fibers contract _______ and _______ .
circumfrentially and longitudinally
Systolic ventricular function depends on:
- LV function
- Compliance of the myocardium
- Preload and Afterload
- LV shape and size
LV contractility is caused by the ________ fibers _______ and _________ .
Myocardial
Elongating
Shortening
LV contractility is affected by:
- MI
- Loading conditions
- pressures
- Heart rate
- blood pressure
- blood viscosity
- stress
- metabolic disorders
Define: Preload
What is let tin the ventricle at end diastole
What lesions affect preload?
Aortic insufficiency
Left Ventricular Hypertrophy
Define: Afterload
Systemic vascular resistance / What the LV has to pump against
LV volumes consist of:
LVED
LVES
What is the equation for Stroke Volume?
SV = LVED - LVES
What is the equation for Cardiac Output?
CO = SV x HR
What are the imaging views for the LV?
- Apical 4,5,2,3
- LV apex from Apical 4
- Short axis at LV
- Modified Apical 4
- Subcostal
What are the parameters for LV Systolic Evaluation?
- LV Volumes (LVED, LVES)
- Simpsons Method, Biplane EF%, Single 4 chamber EF%
- LV Mass
- Relative Wall Thickness
- LV Wall Stress
- dp / dt
What is the equation for LV mass?
LV MASS (ASE) = 1.04 [ (LVED) + IVSD + LVP)^3 - (LVED)^3 x .8 + .6 grams
What are the normal limits for LV MASS for women, men & both?
Women: 66 - 150 g
Men: 96 - 200 g
Both: 50 - 70 g
What is the equation for Relative Wall Thickness?
LVIT
What are the parameters for LV wall stress?
- Longitudinal
- Meridial
- Circumfrential
- Radial
What are the causes of LV remodeling?
- Changes in pressure
- increased stress in the LV
What are the consequences of LV remodeling?
- increased systolic wall tension & stress
- increased MVO2
- Reduced myocyte shortening (contractility)
- reduced subendocardial perfusion
- dysynchronous depolarization / contraction
- conduction delay / dyskinetic myocardium
- mitral regurge
- ventricular arrhythmias (VFIB)
What does dp / dt measure?
the rate of change in LV pressure at systole / LV systolic performance
What does a longer dp / dt mean?
poor LV function, low pressures, low EF%
What are the normal, borderline and abnormal limits for dp / dt?
Normal: > 1200 mmHG/sec or < 27 msec
Borderline: 1,000 - 1,200 mmHG/sec
Abnormal: < 1,000 mmHG/sec or > 32 msec
What is VTI?
Velocity Time Integral
Define: Velocity Time Integral
The distance that a volume of blood travels at systole / the stroke index for 1 beat.
What is the equation for VTI based on?
The volume of a cylinder: base x height
What is the equation for VTI?
VTI = Velocity x Time
What are the units for VTI?
cm
What are the normal limits for RWT for men and women?
Men: .22 - .42
Women: .24 - .4
What are the factors that affect wall stress?
- LV dilation
- LV Hypertorphy
- Increase in overall pressure
- Lesions: AS, MS, etc…
What effect does LV dilation have on LV wall stress?
the myocardium stretches and wall stress increases
What effect does LV hypertrophy have on LV wall stress?
the myocardium thickens and wall stress increases
Can wall stress be measured?
No
LV wall stress can affect a ______ or the _______ LV wall
portion
entire
How do you measure the LVOT diameter (cross sectional area)?
- Measure the LVOT just at the AO valve (@ systole) in PLAX view
- Put that measurement in the CSA equation
CSA = .785 x d^2
What are the two things you need to do a doppler exam of the LV systolic function?
- CSA of the LVOT
2. VTI
What are 4 things a good SV calculation depends on?
- Accurate caliper placement
- Valve must be open
- Where you place the sample volume / Caliper must be 1 cm away from the valve in center of flow
- Good window / clean up TGCs
How do you measure dp / dt?
- adjust sweep speed to 100 mm/sec
- place caliper at MR jet to obtain a doppler reading
- measure the point at which the velocity jet reaches 1 m/sec and another caliper at 3 m/sec
(this represents the time it takes for the pressure change of 32 mmHG to occur) - plug that number into the dp/dt formula:
dp/dt = 32000
———-
time
What are the criteria for using Simpson’s rule / The disk method?
- Ventricle is symmetrically contracting
- apical 4 or 2 chamber
- transducer must be at the true apex
- the beam must go through the center of the left ventricle
What will happen if the criteria for the Disk Method aren’t met?
There is an underestimation of LV volume
How do you calculate LAP?
LAP = E (doppler of MV) / E’ (tissue doppler of MV annulus) x 1.25 + 1.9
What factors do you need in order to calculate LAP?
- Tissue doppler
- E/A Ratio
- MV flow pattern and decel. time
In the LAP equation, what does E represent
doppler of the Mitral Valve
In the LAP equation, what does E’ represent
tissue doppler of the Mitral Valve annulus
