Term
| Calculation of volumetric flow rate is based on |
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Definition
| A simple hydraulic principle which states that the flow rate (Q) through a tube of a constant diameter is directly proportional to the CSA of the tube and the mean velocity of fluid moving through the tub when the orifice CSA is fixed & when the velocity is constant |
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Term
| Given that heart velocity is not constant as blood flow is pulsatile & velocities are constantly changing with systole & diastole, what measure is used to calculate volumetric flow rate? |
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Definition
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Term
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Definition
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Term
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Definition
SV X HR/1000
1000=conversion of milliliters (mL) to liters (L) |
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Term
| Normal values Stroke Volume |
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Definition
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Term
| Normal values: Cardiac Output (L/min) |
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Definition
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Term
| Normal values: Cardiac Index |
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Definition
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Term
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Definition
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Term
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Definition
| The cardiac output indexed for the body surface area |
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Term
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Definition
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Term
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Definition
| BSA m squared=Height X weight/3131 raised 1/2 |
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Term
| CSA area of LVOT is derived from what |
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Definition
| 2-D measurement of LVOT diameter perpdendicular to the aortic root from the inner edge of the junction between the AAW &IVS to the junction of the PAW & AML during systole |
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Term
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Definition
VTI cm=Vmax X LVET
LVET: LV ejection time (s)
Vmax: cm/s |
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Term
| Why is the LVOT the most common site for the calculation of SV & CO |
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Definition
1-LVOTd easiest to measure & most accurate of any other area of the heart
2-LVOTd can be measured in axial resolution (better than lateral resolution)
3-LVOTd more accurate and closer to the true area
4-CSA of the LVOT is constant throughout systole
5-Flow within the entrance of the LVOT has a flat flow profile |
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Term
| How is the aortic diameter obtained? |
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Definition
| From a zoomed view of the Ascending aorta obtained from the PSLA of the LV |
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Term
| How is ascending aorta VTI obtained? |
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Definition
| From the suprasternal window using PW Doppler |
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Term
| How is the CSA of MPA derived? |
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Definition
| From the 2-D measurement of the Max diameter of this vessel during systole |
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Term
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Definition
| From a zoomed view of the MPA obtained from either the PSLA/PSSA views of the RVOT using inner edge-to-inner edge of the vessel lumen |
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Term
| How is the MPA VTI obtained? |
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Definition
| From the PSLA/PSSA views of the RVOT using PW Doppler & measured by tracing the leading edge of the velocity spectrum |
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Term
| How is RVOTd CSA derived? |
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Definition
| From a zoomed view of the RVOT obtained from PSLA/PSSA views & measured perpendicular to the pulmonary artery from the inner edge to inner edge of the RVOT just proximal to the PV |
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Term
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Definition
| Measured by tracing the leading edge of the velocity spectrum from a PSLA/PSSA view; transducer approx. 0.5 cm proximal to the PV leaflets |
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Term
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Definition
| TAd is ;measured in the mediolateral plane from the inner edge to inner edge of leaflet insertion into the myocardium during early diastole |
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Term
| 3 Methods of calculating MV SV, CO & CI output |
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Definition
CSA=.785 X MAd squared
Area=3.14/4 X a X b
a: annular diameter in 1 plane (cm)
b: annular diameter in a plane perpendicular to a (cm)
Mitral valve orifice (MVO) method |
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Term
| T/F Good ejection fraction does not translate into good Cardiac output |
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Definition
| True because with severe mitral regurg, the EF may be normal yet the CO may be significantly reduced because most of the blood ejection is going back into the LA |
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Term
| Limitations to SV & CA calculations |
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Definition
Assumptions of volumetric flow calculations
Error in VTI measurements
Error in the diameter measurement
Overestimation of the CO with valvular regurg |
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Term
| When there is aortic regurg, how is calculation of CO corrupted? |
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Definition
| Calculation of CO using the LVOT will include the regurg volume as well as forward SV thus overestimating the CO |
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Term
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Definition
| A measure of the rate of rise of ventricular pressure during isovolumic contraction |
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Term
| How is peak positive dP/dt accurately measured? |
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Definition
| Noninvasively from the CW Doppler signals of MV regurg & TV regurg |
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Term
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Definition
dP/dt=32/delta t
dP/dt: Rate of pressure rise over time (mmHg/s)
32: the pressure difference between 1 m/s and 3 m/s using the simplified Bernoulli equation: 4(3) squared - 4(1) squared=32 mmHg
Delta t: time interval between 1 m/s & 3 m/s points |
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Term
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Definition
| The time it takes for the LV to generate X-amount of mm Hg of pressure during isovolumic contraction |
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Term
Normal values: dP/dt
Time taken for LV to generate 32 mm Hg |
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Definition
> 1200 mmHg/s
<0.27 s (27 ms) |
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Term
Mild-moderate dysfunction: dP/dt
Time taken for LV to generate 32 mm Hg |
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Definition
800-1200 mm Hg/s
0.027-0.04 s (27-40 ms) |
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Term
Severe dysfunction: dP/dt
Time taken for LV to generate 32 mm Hg |
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Definition
< 800 mm Hg/s
>0.04 (40 ms) |
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Term
| Utilizing dP/dt to assess RV systolic function what is the time interval for usual measurement? |
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Definition
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Term
| Using Bernoulli's equation what is the dP/dt or change in pressure over time for RV systolic function? |
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Definition
| 16 mm Hg/s during isovolumic contraction time |
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Term
| Limitations of dP/dt in the assessment of ventricular systolic function |
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Definition
Acute MV regurg
Inadequate Doppler signal
Significant Aortic stenosis or hypertension
Significance of the dP/dt for TV regurg |
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Term
| 3 layers of myocardial muscle fibers |
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Definition
Oblique
Circumferential
Longitudinal |
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Term
| What imaging allows for measuring the longitudinal Doppler velocities within the myocardium |
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Definition
| Doppler tissue imaging (DTI) |
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Term
| 3 distinct waveforms characterizing the myocardial velocity profile as obtained by pulsed DTI in apicals |
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Definition
apically directed systolic myocardial velocity (Sm)
EArly diastolic atrially directed myocardial velocity (Em)
Late diastolic atrially directed myocardial velocity (Am) |
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Term
| Normal values for Sm velocities of the LV vary |
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Definition
The wall sampled
The sampling site within each wall
The patient age |
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Term
| Normal values for RV Sm velocities vary |
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Definition
Sampling site along the RV lateral wall but unlike the MV Sm velocities
TV Sm velocities are not significantly affected by patient age |
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Term
| Limitations of Sm in the Assessment of Ventricular systolic function |
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Definition
Localized velocities
Angle of Intercept
Pulsed DTI vs. Color DTI |
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Term
| Limitations of Sm in the Assessment of Ventricular systolic function |
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Definition
Localized velocities
Angle of Intercept
Pulsed DTI vs. Color DTI |
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Term
| What is one of the principal limitations of DTI in assessing systolic ventricular function? |
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Definition
| Inability to differentiate actiavely contracting myocardium from passive myocardial motion |
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Term
| Strain & strain rate imaging have the potential to overcome what? |
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Definition
| Inability to differentiate actively contractin myocardium from passive myocardial motion in DTI assessment |
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Term
| Scientific definition of strain |
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Definition
| Deformation as a result of applied stress while strain rate (SR) refers to the rate of the deformation |
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Term
| Another definition of strain |
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Definition
| The fractional change from the original dimension; referred to as Lagrangian strain |
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Term
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Definition
ST=e/delta t
SR: strain rate (/s or s -1)
e: strain (unitless)
Delta t: change in time (s) |
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Term
| what is a standard M-mode trace of the LV a measure of? |
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Definition
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Term
| In echocardiography one-dimensional e and SR may be derived from what? |
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Definition
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Term
| Myocardial SR & strain (e) can be e measured in 3 directions or axes? In what views |
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Definition
Radial axis
Longitudinal axis
Circumferential axis
Standard transthoracic echo views along the axial plane of the ultrasound beam |
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Term
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Definition
| "expansion" in the myocardium; lengthening or thickening of tissue |
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Term
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Definition
| compression in the myocardium; either shortening or thinning of tissue |
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Term
| T/F Positive e/SR can occur in the longitudinal or circumferential axis |
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Definition
| True while negative e/SR occurs in radial axis |
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Term
| What color is displayed for positive SR in Doppler CFI? Negative SR? Zero SR? |
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Definition
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Term
| Limitations of DTI-derived strain & strain Rate |
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Definition
Marked angle dependency
Relatively poor signal-to-noise ratio
Measurements are made in the axial direction of the beam therefore providing only one dimensional estimations of myocardial deformation
e is derived by integrating the SR curve
Radial and circumferential axes can only be assessed in limited views |
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Term
| Define speckle track imaging |
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Definition
| Identification & tracking of unique acoustic speckles within the myocardium over successive frames |
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Term
| How are acoustic speckles created? |
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Definition
| By interference of the reflected ultrasound within the myocardium |
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Term
| How are acoustic speckles tracked? |
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Definition
| In both apical (longitudinal & transverse directions) & pssa axis (radial & circumferential directions) views |
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Term
| What is the advantage of STI e and STI SR over DTI e and SR? |
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Definition
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Term
| Clinical applications of Strain & strain rate |
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Definition
Evaluation of L/R ventricular systolic function
Assessment of diastolic function
Identification of myocardial involvement in systemic diseases
Identification of myocardial ischemia
Quantification of stress echocardiography
Detection of myocardial viability |
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Term
| What does the myocardial performance index (MPI) reflect? |
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Definition
| "Global" myocardial performance & incorporates both the elements of systole & diastole |
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Term
| What conditions is the MPI particularly useful in assessing? |
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Definition
Dilated cardiomyopathy
Cardiac amyloidosis
Pulmonary hypertension
RV infarction
RV dysplasia
Congenital heart disease |
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Term
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Definition
| A ration between the isovolumic contraction time (IVCT) plus the isovolumic relaxation time (IVRT) and the ejection time (ET) |
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Term
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Definition
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Term
| Principal advantage of MPI |
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Definition
| Measurement can be derived from 2 simple measurements which can be readily measured during the routine Doppler exam |
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Term
| 4 methods to calculate MPI |
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Definition
Spectral Doppler & measurement of 2 intervals
Spectral Doppler & measurement of 4 intervals
DTI & measurement of 2 intervals
M-mode with 2 measurements: MV & AoV |
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Term
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Definition
PW & m-mode methods (methods 1,2 and 4)--accuracy risk
DTI method may not reflect overall ventricular function
Arrhythmias
Organic valvular disease
Loading conditions |
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