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Left Ventricle: Ischemia and Function Small Group Discussion Mark A. Taylor, MD Allegheny Health Network Temple University Pittsburgh, PA John Fox, MD Brigham and Women’s Hospital Boston, MA Learning Objectives: 1. Review the normal LV anatomy and function using 2D ultrasound and Doppler. 2. Describe systolic LV function using 2D ultrasound and Doppler under conditions of alterations in loading conditions, dyssynchrony and pacing effects. 3. Describe how to calculate different echocardiographic measures of left ventricular volume and function 4. Recognize the echocardiographic manifestations of regional LV systolic dysfunction. Case 1: A 64 yo presents for elective coronary artery bypass graft surgery for severe three-vessel coronary artery disease. Planned surgical approach is a LIMA to the LAD and SVGs to the RCA and CX distribution. Question: What standard views will you obtain to evaluate LV global and segmental function? Key point: To evaluate LV global and segmental function, 6 standard views of the heart are obtained and include: ME 4-chamber ME 2-chamber ME LAX TG Midpapillary SAX TG Basal SAX TG Apical SAX Question: Describe how you will systematically evaluate LV global systolic function? Key point: Evaluate all 6 images and assess overall contractility qualitatively and quantitatively. Overall wall motion and systolic thickening of all 16 segments should be included in this global measure. Qualitative interpretation should be followed by quantitative measures. Ejection fraction represents the difference between EDVESV/EDV x 100 or SV/EDV x 100. Normal systolic ejection fraction is 55-70%. Measurements below 52% in males and 54% in females are abnormal and lower values are consistent with evidence of heart failure or cardiomyopathy. An EF between 40 and 55% indicates myocardial damage but may not represent heart failure. Heart failure is classified as either: Heart failure with preserved ejection fraction (HFPEF) -diastolic heart failure Heart failure with reduced ejection fraction (HFREF) -systolic heart failure. Question: Describe how you will systematically evaluate the LV segmental function? Key point: Evaluate all 6 imaging views for the left ventricle and on each image the corresponding 6 or 4 segments at each level of the ventricle (apex, mid pap, and base). To each segment assess regional function, inward radial motion, and systolic wall thickening. Regional Function Normal or hyperkinesis Hypokinesis Akinesis Dyskinesis Grade 1 Inward Radial Motion > 30% Systolic Wall Thickening Marked 2 3 4 10% to 29% <10% Paradoxical systolic motion Reduced Negligible Systolic Thinning Aneurysmal or Grade 5 is no longer a recommended wall motion grade and aneurismal segments can be either akinetic or dyskinetic. Case 2: An 86 year old patient presents for a coronary artery bypass graft. The surgeon asks you to assess global and regional function. You see the referring cardiologist and the cardiologist ask you what the patients wall motion score index is for this patient. Your assessment is as follows: Level Segment(s) Basal (6) Anterior Anteroseptum Inferoseptum Inferior Inferolateral Anterolateral Anterior Anteroseptum Inferoseptum Inferior Inferolateral Anterolateral Anterior Septal Inferior Lateral Apical cap MidPapillary (6) Apex (4 or 5) Regional Function Grade 2 2 1 1 1 2 3 3 2 1 1 4 4 4 4 4 - Key Point: Wall motion score index is a semi-quantitative analysis of regional function and equals sum of all scores divided by the number of segments visualized. In the example above, WMSI = 39/16 which equates to 2.44. A normal ventricle with no segmental wall motion abnormalities will have a WMSI of 1 and increasing values of WMSI towards 4 indicates more significant regional wall motion abnormalities. Case 3: You are called urgently into small bowel resection for an elderly female suffering from a long-standing small bowel obstruction. She presented to the OR dehydrated and anemic. After induction, she becomes hypotensive and despite 2 liters of IV fluid and two units of packed red blood cells remains hypotensive and is on a neosynephrine infusion. You are asked to perform an urgent transesophageal echocardiogram to assess for left ventricular volume and function. Question: How do you assess left ventricular preload by transesopheageal echocardiography? Question: How do changes in contractility and SVR affect TEE findings? Key Points: Echocardiography can be utilized to qualitatively and semiqualitatively assess preload as the volume at the end of diastole. Left ventricular end diastolic area (EDA) may serve as a surrogate for preload. Graded hypovolemia, in both pediatric and adult patients demonstrate changes in LVEDA (TG mid pap SAX), which mirror changes in volume status. EDA index (cm2/m2) = LVEDA/BMI An EDA indexed to BSA less than 5.5 cm2/m2 defines hypovolemia. A decrease left ventricular end systolic area (ESA) or end-systolic cavity obliteration can suggest hypovolemia but has low specificity for predicting a decrease in preload. In addition to hypovolemia, an increase in ejection fraction or a decrease in systemic vascular resistance can lead to end systolic cavity obliteration. Question In this same hypovolemic patient, how do you calculate the following quantitative parameters of LV function? Fractional Shortening Fractional Area Change LVOT Stroke Volume and cardiac output Ejection Fraction? Key Points: Transesophageal echocardiography can be used to calculate the following quantitative parameters of LV function: Fractional Shortening: % FS = [(LVEDD-LVESD) / LVEDD] x 100 Based upon mmode echocardiography and ventricular diameters Fractional area change: %FAC = [(LVEDA-LVESA)/LVEDA] x 100 Based upon 2D imaging of TG mid papillary area measurement LVOT Stroke Volume and cardiac output SV = Area x VTI where area is the area of the LVOT or the aortic valve and VTI is the velocity time integral of blood passing through the respective area being measured. CO = SV x HR Ejection Fraction EF = (EDV-ESV/EDV) x 100 Volumes obtained by Simpson’s Method of disc measurements from the ME 4chamber and ME 2-chamber views. One may use 3D TEE to obtain accurate volumes by 3D analysis. Case 4: You have just completed an Aortic Valve Replacement (AVR) and the patient is requiring pacing to separate from cardiopulmonary bypass due to conduction block following surgery. Question: function? Question: How does ventricular pacing with epicardial wires affect left ventricular How do other conduction abnormalities affect left ventricular function? Key Points: Ventricular pacing and intraventricular conduction delays can create regional wall motion abnormalities including septal dyskinesis. In the immediate post bypass period, echocardiographic examination of regional wall motion can be evaluated with patients paced and unpaced (if appropriate) to determine the effects of pacing. Case 5: You are contemplating upgrading your TEE service line to all 3D equipment and are asked to write a proposal outlining the clinical benefits for your chairman. Question: How will 3D TEE change your approach to the qualitative evaluation of LV systolic function? Question: How will 3D TEE change your approach to the quantitative evaluation of global systolic function including ventricular volumes and ejection fraction? Question: How will 3D TEE change your approach to the qualitative and quantitative evaluation of regional left ventricular function? Key Points: Advantages of 3D ventricular volume measurements over 2D techniques include avoidance of geometric assumptions. Complete systolic and diastolic volumes can be obtained and then calculation of volume-based functions including stoke volume and ejection fraction can be determined. Global left ventricular volumes, EF measurements and function using real-time 3D TEE is quick, more accurate and reproducible than with 2D echocardiography and correlate highly with cardiac MRI. Interobserver variability in volume determination is less with 3D echocardiography in comparison to 2D. 3D echocardiography has been demonstrated to be useful in the assessment of global and regional left ventricular wall motion and quantification of systolic dyssynchrony. A systolic dyssynchrony index (SDI) may be calculated which is the standard deviation of regional ejection times. A recent study by Meris, et al, investigating intraoperative 3D TEE and its role in quantification of LV global function, demonstrated that image acquisition time, and reproducibility was not statistically different than conventional 2D imaging. 3D TEE quantification though was associated with larger volumes and longer analysis times but these larger volumes did not affect the overall LV function classification models. Based upon the closer limits of agreement with MRI and better reproducibility the 2D echocardiography, 3D echocardiography can be recommended for standard utilization to determine LV volumes and ejection fraction. As stated by the EAE/ASE consensus statement regarding 3D echocardiography, “3D TTE and TEE assessment of LV volumes and ejection fraction is recommended over the use of 2D echocardiography.” Further Reading: 1. Reeves ST, Finley AC, Skubas NJ, et al. Basic perioperative transesophageal echocardiograpy examination: A consensus statement of the American Society of Echocardiography and the Society of Cardiovascular Anesthesiologist. Anes Analg 2013;117:543-558. 2. Hahn RT, Abraham T, Adams MS, et al. Guidelines for performing a comprehensive transesophageal echocardiographic examination: Recommendations from the American Society of Echocardiography and the Society of Cardiovascular Anesthesiologists. Anes Analg 2014;118:21-68. (also in J Am Soc Echocardiogr 2013;26:921-964.) 3. Lang RM, Bierig M, Devereux RB, et al. Recommendations for chamber quantification: A report from the American Society of Echocardiography’s Guidelines and Standards Committee and the Chamber Quantification Writing Group, developed in conjuction with the European Association of Echocardiography, a branch of the European Society of Cardiology. J Am Soc Echocardiogr 2005;17:1086-1119. 4. Lang RM, Badano LP, Mor-Avi V, et al. Recommendations for cardiac chamber quantification by echocardiography in adults: An update from the American Society of Echocardiography and the European Association of Cardiovascular Imaging. J Am Soc Echocardiogr 2015;28:1-39. 5. Meris A, Satambrogio L, Casso G, et al. Intraoperative three-dimensional versus two-dimensional echocardiography for left ventricular assessment. Anes Analg 2014;118:711-720. 6. Lang RM, Badano LP, Tsang W, et al. EAE/ASE recommendations for image acquistion and display using three-dimensional echocardiography. J Am Soc Echocardiogr 2012;25:3-46.