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Turandot Saul December 19, 2007
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Strengths Can assess morphology and function Cheap No radiation Portable Readily available
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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
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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
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Ejection Fraction Depends on contractility, preload and afterload, heart rate, synchronicity of contractions Global parameter, regional differences in contractility averaged
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Ejection Fraction Qualitative - visual inspection - severity: mild, moderate, severe - focality - global: reported as a range in intervals of 5-10% - regional: 17 segments
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Global Function - PSLA Normal Cardiomyopathy
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Global Function - PSSA Normal Cardiomyopathy
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17 Cardiac Segments
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Inferior Wall - PSLA
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Inferior Wall - PSSA
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Anterior Wall - PSLA
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Anterior Wall - PSSA
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Ejection Fraction Quantitative - accuracy, reproducibility limited - assumes shape of LV cavity - best in symmetric ventricles
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Simpson’s Rule – the biplane method of disks Volume left ventricle - manual tracings in systole and diastole - area divided into series of disks - volume of each disk ( πr 2 * h ) summed = ventricular volume LV-ED LV-ES A4C A2C
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Simpson’s Rule – the biplane method of disks Once volumes determined, EF is calculated : LV diastolic volume - LV systolic volume x 100% LV diastolic volume Normal > 50%, 35 to 50% moderately depressed, <35% severely depressed Edge detection software can identify borders
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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
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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
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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%.
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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 ( 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
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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
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Diastolic function Impaired diastolic relaxation LV wall thickness usually increased Increase LA size
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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 Video: Yale Cardiothoracic Imaging www.med.yale.eduwww.med.yale.edu
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