Download Left Ventricular Function

Turandot Saul
December 19, 2007
ULTRASOUND DETERMINATION OF
LEFT VENTRICULAR FUNCTION
Strengths
 Can assess morphology and function
 Cheap
 No radiation
 Portable
 Readily available
Limitations
 Finding an acoustic window
- narrow inter-costal spaces
- all regions of LV not visualized in all patients
- obesity
- intervening lung tissue in pt with COPD
- musculoskeletal deformities e.g. kyposis,
pectus excavatum
Left Ventricular Function
 Fills at low enough pressures to not cause
pulmonary congestion
 Deliver enough blood to periphery at high
enough pressure to perfuse tissues
No one quantity measures these
assessments of performance
- ejection fraction
Ejection Fraction
 Depends on contractility, preload and
afterload, heart rate, synchronicity of
contractions
 Global parameter, regional differences in
contractility averaged
Ejection Fraction
• Qualitative - visual inspection
- severity: mild, moderate, severe
- focality
- global: reported as a range in
intervals of 5-10%
- regional: 17 segments
Global Function - PSLA
Normal
Cardiomyopathy
Global Function - PSSA
Normal
Cardiomyopathy
17 Cardiac Segments
17 Cardiac Segments
Inferior Wall - PSLA
Inferior Wall - PSSA
Anterior Wall - PSLA
Anterior Wall - PSSA
Ejection Fraction
• Quantitative
- accuracy, reproducibility limited
- assumes shape of LV cavity
- best in symmetric ventricles
Simpson’s Rule – the biplane
method of disks
LV-ED
 Volume left ventricle
- manual tracings in systole and
A4C
diastole
- area divided into series of disks
- volume of each disk ( πr2 * h )
summed = ventricular volume
A2C
LV-ES
Simpson’s Rule – the biplane
method of disks
 Once volumes determined, EF is calculated :
LV diastolic volume - LV systolic volume
LV diastolic volume
x 100%
 Normal > 50%, 35 to 50% moderately depressed,
<35% severely depressed
 Edge detection software can identify borders
Limitations
 Operator dependence
- inter/intra observer variability is 10-30%
 Limited utility
- MR high EF but little forward flow
- AS low EF but possibly reversible
Superiority of Visual Versus Computerized
Echo Estimation of Radionuclide LVEF
- Amico, A. American Heart Journal, 1989

Blinded study, 44 patients

Gold Standard - equilibrium radionuclide angiography (ERNA)

Echocardiographic methods included:
1. Cubed M-mode formula
2. Teichholz M-mode formula
3. Subjective estimation of LVEF from two-dimensional videotape
4. Area-length method in one four-chamber view
5. Average of area-length method in three four-chamber views
6. Average of area-length method in four-chamber and two-chamber views (one beat each)
7. Subjective estimation from stored videoloop of four-chamber and two-chamber view

Best correlation method 3 - subjective estimation by experienced cardiologist

More time-consuming and costly computer techniques yielded worse estimates
Determination of LV Function by EP
Echocardiography of Hypotensive Patients
- Moore, C. Academic Emergency Medicine, 2002
 Prospective, observational study, convenience sample
 Four EPs, focused echo training
 51 patients with symptomatic hypotension
 Blinded cardiologist reviewed studies
 Pearson's correlation coefficient R = 0.86.
 Echo quality rated as good 33%, moderate 43%, poor 22%.
Accuracy of Emergency Physician Assessment
of Left Ventricular Ejection Fraction
– Randazzo, M. Academic Emergency Medicine, 2003
 Cross-sectional observational study, convenience sample
 115 patients, chest pain (45.1%), congestive heart failure





(38.1%), dyspnea (5.7%), and endocarditis (10.6%)
Three-hour training session
LVEF poor (<30%), moderate (30%-55%), or normal (>55%)
Formal echo within four hours interpreted by cardiologist.
LVEF correlation 86.1% overall agreement
Highest (91%) in normal LVEF category, 70.4% poor LVEF,
47.8% moderate LVEF
Clinical utility
 Patients with active chest pain
- regional wall motion abnormality
- high sensitivity for ischemia or infarction;
absence excludes it
- moderately specific
 Prognostic information short and long term
 Other diagnosis: PE, dissection, tamponade
Diastolic function
 Impaired diastolic relaxation
 LV wall thickness usually increased
 Increase LA size
Sources

UptoDate: Noninvasive methods for measurement of left ventricular systolic function

Zipes: Braunwald’s Heart Disease: A Textbook of Cardiovascular Diseases. Elsevier Inc, 2007.

Directed bedside transthoracic echocardiography: preferred cardiac window for left ventricular
ejection fraction estimation in critically ill patients. American Journal of Emergency Medicine Volume 25, Issue 8 (October 2007) - Copyright © 2007 W. B. Saunders Company

Accuracy of emergency physician assessment of left ventricular ejection fraction and central
venous pressure using echocardiography. Randazzo MR - Acad Emerg Med - 01-SEP-2003; 10(9):
973-7

Determination of left ventricular function by emergency physician echocardiography of
hypotensive patients.
Moore CL - Acad Emerg Med - 01-MAR-2002; 9(3): 186-93

Subjective visual echocardiographic estimate of left ventricular ejection fraction as an alternative
to conventional echocardiographic methods: comparison with contrast angiography.
Mueller X - Clin Cardiol - 01-NOV-1991; 14(11): 898-902

Superiority of visual versus computerized echocardiographic estimation of radionuclide left
ventricular ejection fraction.
Amico AF - Am Heart J - 01-DEC-1989; 118(6): 1259-65
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Video: Yale Cardiothoracic Imaging www.med.yale.edu