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Increased myocardial cyclic variation of integrated backscatter and oxygen consumption in patients with ischemic cardiomyopathy with inotropic stimulation
392
30D
~ournal o f the American Society o f Echocardiography May-June 1995
Abstracts
DOPPLER TISSUE IMAGING OF MYOCARDIAL VELOCITY: PHYSIOLOGIC VARIABILITY IN NORMALS David C. Griffin, M.D., Joann Anman, and William R. Davidson, Jr., M.D., Penn State University, Hershey, PA
32D
Doppler Tissue hnaging (DTI) is a new echocardiographic modality using Doppler shifts in the imaging frequency to color encode myocardial velocities. This study was undertaken to establish peak systolic and diastolic myocardial absolute velocities in normals. Both thickening and translational motion of the left ventricular posterior wall (LVPW), intravemricular septum (IVS), and right ventricular free wall (RVFW) were measured.
T o determine whether ultrasonic tissue characterization with integrated backscatter (IB) and the slope o f attenuation (13) can d e t e c t ventricular r e m o d e l i n g in / ~ r e s s u r e - o v e r l o a d left ventricular hypertrophy ( L V H ) , eight :4-wk old m a l e SpragueD a w l e y rats u n d e r w e n t b a n d i n g o f the suprarena'I aorta (bandei:l g r o u p ) , and 11 rats underwent s h a m s u r g e r y (normal group). Rats were killed at approximately 1 y e a r (42 - 53 wk). H e a r t s w e r e excised, f i x e d in f o r m a l i n and cut in 500 [am thick sections. T h e backscattered r a d i o - f r e q u e n c y data f r o m the m i d - m y o c a r d i u m s e c t i o n s w e r e a c q u i r e d f r o m 1200 independent sites f r o m each s p e c i m e n with a 50 M H z acoustic microscope for calculation of integrated backscatter c o m p e n s a t e d for attenuation (IB) and the ]3, I B / v a s expressed in decibels (dB) r e l a t i v e to s c a t t e r i n g f r o m a s t e e I p l a t e . Attenuation was calculated by a standard substitution method.
Methods: 20 normal subjects, (10 males and 10 females) with a mean age of 33 years (range 22-53) were imaged using DTI at 4.0 MHz. In the parasternal long axis (PLA) view the ultrasound beam is nearly perpendicular to LVPW, IVS, and RVFW thickening. In the apical four-chamber (A4C) view the IVS and RVFW thicken in a perpendicular vector relative to the ultrasound beam. These velocities therefore reflect translational motion predominantly. Only velocities with a sampling angle of< 20~ were used. Velocity scaIes were set to avoid afiasing. The peak velocities were measured online using a color tag to identify areas of maximal myocardial velocity (mean of ->3 measurements). Results: absolute velocity mean • SD (cm/sec). Thickening Systolic Diastolic LVPW-PLA 0.43 + 0.16 0.51 + 0.16. p .01 IVS PLA 0.46 • 0.13 0.42 • 012 RVFW-PLA 047 -+ 0.18 0,49 -+ 0.20 Translation RVFW-A4C 1.07 -+ 0.23 I. 12 -+ 0.25* p - 01 [VS~A4C 0.68 • 0.24 0.78 • 0,18 There is an association between peak systolic and diastolic velocities for each wall in a given subject ( r = 0,55-0.86, p<0.001).* There was no association between left and right ventricular or IVS and LVPW myocardial velocities in a given subject.
Normal LVmass index(mg/gm) 1.98_+ 0.08 Collagen 42.5 _+ 1.3 IB (dB) -44.9_+ 0.8 (dB/cm-MHz) 1.55 _+0.06
COMPARISON OF INTEGRATED BACKSCATTER AND CONVENTIONAL ULTRASOUND TISSUE CHARACTERIZATION DURING EXPERIMENTAL CORONARY OCCLUSION Paul A. Tamburro, MD, Peter W. Kakavas, MD, Alex Neumann, BS, Donald H. Tanis, MD, Dae H. Kim, MS, Gary L. Schaer, MD, Philip R. Liebson, MD, Richard H. Marcus, MD, Jeffrey S. Soble, MD; Rush Medical College, Chicago, IL Cyclic variation in the acoustic intensity (CV-AI) of reflected ultrasound from myocardium is attenuated in zones of ischemia. The sensitivities of integrated backscatter (IBS) and conventional ultrasound (US) for detection of ischemiainduced attenuation of CV-AI have not been previously compared. We studied the effects of acute coronary occlusion on CV-AI in a dog model usingacoustic densitometry lAD) software, applied to IBS and US imagos. Transthoracic LV short axis IBS and US images obtained at the papillary muscle level were analyzed in 9 dogs at baseline and 60 minutes into balloon occlusion of the LAD. AD was applied to the ischemic zone and a contralateral control region at baseline and after coronary occlusion. CV-AI (mean + SD, in dB) was determined: Region ~schemic
Image IBS US IBS US
Baseline Occlusion 4 8 + 1.5 2.2• Q7 5.1+4.1 3.6• 1.9 3.9+ 1.4 4.1 + 1.2 3.7+ 1.9 3.9:~ 1.6
p value 0.002 0.13 0.66 0.70
Baseline CV-AI was similar by both imaging techniques. During LAD occlusion, statistically significant attenuation in CV-AI was detected in the ischemic region only in IBS images. There was no attenuation of CV-AI in the control region during LAD occlusion in either IBS or US images. Conclusion: AD applied to either IBS or US images identifies CV-AI in normal myocardium However, only IBS is sufficiently sensitive to detect attenuation of CV-AI during LAD occlusion in this dog model.
Banded p value 3.01 + 0.15 <0.0001 51.9 + 2.8 0.0034 -41.2_+ 1.2 0.0686 2.06 + 0, [5 0.0021
T h e aortic banded rats d e v e l o p e d L V H a c c o m p a n i e d by the characteristic i n c r e a s e in c o l l a g e n c o n c e n t r a t i o n in the left ventricle. IB i n c r e a s e d 2.3-fold in the L V H a n i m a l s , a c h a n g e o f borderline significance. T h e [3 w a s significantly h i g h e r in the rats with L V H . T h e s e f i n d i n g s s u g g e s t that both I B and a t t e n u a t i o n r e f l e c t the a m o u n t ot c o l l a g e n in h y p e r t r o p h i c ventricles. T h u s d e l i n e a t i o n o f structural r e m o d e l i n g o f m y o c a r d i a l ttssue b y u l t r a s o m c t i s s u e characterization permits assessment of altered material properties in left ventricular hypertrophy.
Conclusion: l) Translational velocities are greater than thickening velocities. 2) The mean left and right ventricular myocardial velocities are similar, but these are not similar in a given subject. 3) There is an association between peak systolic and diastolic myocardial velocities in a given wall in normals. 4) Absolute LVPW and RVFW diastolic (relaxation) velocities are greater than systolic velocities.
31D
ULTRASONIC TISSUE CHARACTERIZATION OF REMODELING IN LEFT VENTRICULAR HYPERTROPHY Victor G. D~vila-Rom~in, MD, Glenn E. Davison, MD, Christopher S. Hall, MS, James G. Millet, PhD, Samuel A. Wickline, MD Washington University School of Medicine, St. Louis, Missouri.
33D
INCREASED MYOCARDIAL CYCLIC VARIATION OF INTEGRATED BACKSCATTER AND OXYGEN CONSUMPTION IN PATIENTS WITH ISCHEMIC CARDIOMYOPATHY WITH INOTROPIC STIMULATION Victor G. D~ivila-Romfin, MD, Patficia J. Rubin, MD, Hiie M. Gnssak, MD, Julio E. Pdrez, MD, Robert L Gropler, M D Washington University School of Medicine, St. Louis, Missouri. It is well established that cyclic variation of integrated backseatter (CVIB) is not altered by inotropic stimulation in normal human myocardium. H o w e v e r , the response of C V I B to inotropic stimulation in mechanically dysfunctional myocardium is unknown. Accordingly, we m e a s u r e d CVIB at rest and during the administration of intravenous dobutamine (average 14 ug/kg/min) in nine patients, all males (average age 59 years) with ischemie cardiomyopathy. To ascertain whether changes in myocardial energy metabolism and mechanical function were associated with changes in CVIB, regional myocardial o x y g e n consumption (measured by positron emission tomography and C-11 acetate) and percent wall t h i c k e n i n g ( m e a s u r e d by t w o - d i m e n s i o n a l echocardiography) were obtained simultaneously. Measurements were performed in the proximal and mid-interventrieular septum and the proximal and mid-posterior wall (n = 29 paired segments). Under resting conditions CVIB averaged 1.4 _+0.3 dB and increased to 1.9 -+ 0.4, p < 0.005 during dobutamine stimulation. This change was paralleled by a 50% -+ I0%, (p < 0.0001) and a 39% -+ 14% (p = 0.0002) increase in myocardial oxygen consumption and percent wall thickening, respectively, compared with resting conditions. Thus, in contrast to normal myocardium, CVIB in mechanically dysfunctional m y o c a r d i u m can be a u g m e n t e d by inotropic stimulation. These changes are paralleled by increases in myocardial energy metabolism and mechanical function. The responsiveness of CVIB in this setting m a y have important implications for the use of this measurement in the detection of ischemic but viable myocardium.
30D
~ournal o f the American Society o f Echocardiography May-June 1995
Abstracts
DOPPLER TISSUE IMAGING OF MYOCARDIAL VELOCITY: PHYSIOLOGIC VARIABILITY IN NORMALS David C. Griffin, M.D., Joann Anman, and William R. Davidson, Jr., M.D., Penn State University, Hershey, PA
32D
Doppler Tissue hnaging (DTI) is a new echocardiographic modality using Doppler shifts in the imaging frequency to color encode myocardial velocities. This study was undertaken to establish peak systolic and diastolic myocardial absolute velocities in normals. Both thickening and translational motion of the left ventricular posterior wall (LVPW), intravemricular septum (IVS), and right ventricular free wall (RVFW) were measured.
T o determine whether ultrasonic tissue characterization with integrated backscatter (IB) and the slope o f attenuation (13) can d e t e c t ventricular r e m o d e l i n g in / ~ r e s s u r e - o v e r l o a d left ventricular hypertrophy ( L V H ) , eight :4-wk old m a l e SpragueD a w l e y rats u n d e r w e n t b a n d i n g o f the suprarena'I aorta (bandei:l g r o u p ) , and 11 rats underwent s h a m s u r g e r y (normal group). Rats were killed at approximately 1 y e a r (42 - 53 wk). H e a r t s w e r e excised, f i x e d in f o r m a l i n and cut in 500 [am thick sections. T h e backscattered r a d i o - f r e q u e n c y data f r o m the m i d - m y o c a r d i u m s e c t i o n s w e r e a c q u i r e d f r o m 1200 independent sites f r o m each s p e c i m e n with a 50 M H z acoustic microscope for calculation of integrated backscatter c o m p e n s a t e d for attenuation (IB) and the ]3, I B / v a s expressed in decibels (dB) r e l a t i v e to s c a t t e r i n g f r o m a s t e e I p l a t e . Attenuation was calculated by a standard substitution method.
Methods: 20 normal subjects, (10 males and 10 females) with a mean age of 33 years (range 22-53) were imaged using DTI at 4.0 MHz. In the parasternal long axis (PLA) view the ultrasound beam is nearly perpendicular to LVPW, IVS, and RVFW thickening. In the apical four-chamber (A4C) view the IVS and RVFW thicken in a perpendicular vector relative to the ultrasound beam. These velocities therefore reflect translational motion predominantly. Only velocities with a sampling angle of< 20~ were used. Velocity scaIes were set to avoid afiasing. The peak velocities were measured online using a color tag to identify areas of maximal myocardial velocity (mean of ->3 measurements). Results: absolute velocity mean • SD (cm/sec). Thickening Systolic Diastolic LVPW-PLA 0.43 + 0.16 0.51 + 0.16. p .01 IVS PLA 0.46 • 0.13 0.42 • 012 RVFW-PLA 047 -+ 0.18 0,49 -+ 0.20 Translation RVFW-A4C 1.07 -+ 0.23 I. 12 -+ 0.25* p - 01 [VS~A4C 0.68 • 0.24 0.78 • 0,18 There is an association between peak systolic and diastolic velocities for each wall in a given subject ( r = 0,55-0.86, p<0.001).* There was no association between left and right ventricular or IVS and LVPW myocardial velocities in a given subject.
Normal LVmass index(mg/gm) 1.98_+ 0.08 Collagen 42.5 _+ 1.3 IB (dB) -44.9_+ 0.8 (dB/cm-MHz) 1.55 _+0.06
COMPARISON OF INTEGRATED BACKSCATTER AND CONVENTIONAL ULTRASOUND TISSUE CHARACTERIZATION DURING EXPERIMENTAL CORONARY OCCLUSION Paul A. Tamburro, MD, Peter W. Kakavas, MD, Alex Neumann, BS, Donald H. Tanis, MD, Dae H. Kim, MS, Gary L. Schaer, MD, Philip R. Liebson, MD, Richard H. Marcus, MD, Jeffrey S. Soble, MD; Rush Medical College, Chicago, IL Cyclic variation in the acoustic intensity (CV-AI) of reflected ultrasound from myocardium is attenuated in zones of ischemia. The sensitivities of integrated backscatter (IBS) and conventional ultrasound (US) for detection of ischemiainduced attenuation of CV-AI have not been previously compared. We studied the effects of acute coronary occlusion on CV-AI in a dog model usingacoustic densitometry lAD) software, applied to IBS and US imagos. Transthoracic LV short axis IBS and US images obtained at the papillary muscle level were analyzed in 9 dogs at baseline and 60 minutes into balloon occlusion of the LAD. AD was applied to the ischemic zone and a contralateral control region at baseline and after coronary occlusion. CV-AI (mean + SD, in dB) was determined: Region ~schemic
Image IBS US IBS US
Baseline Occlusion 4 8 + 1.5 2.2• Q7 5.1+4.1 3.6• 1.9 3.9+ 1.4 4.1 + 1.2 3.7+ 1.9 3.9:~ 1.6
p value 0.002 0.13 0.66 0.70
Baseline CV-AI was similar by both imaging techniques. During LAD occlusion, statistically significant attenuation in CV-AI was detected in the ischemic region only in IBS images. There was no attenuation of CV-AI in the control region during LAD occlusion in either IBS or US images. Conclusion: AD applied to either IBS or US images identifies CV-AI in normal myocardium However, only IBS is sufficiently sensitive to detect attenuation of CV-AI during LAD occlusion in this dog model.
Banded p value 3.01 + 0.15 <0.0001 51.9 + 2.8 0.0034 -41.2_+ 1.2 0.0686 2.06 + 0, [5 0.0021
T h e aortic banded rats d e v e l o p e d L V H a c c o m p a n i e d by the characteristic i n c r e a s e in c o l l a g e n c o n c e n t r a t i o n in the left ventricle. IB i n c r e a s e d 2.3-fold in the L V H a n i m a l s , a c h a n g e o f borderline significance. T h e [3 w a s significantly h i g h e r in the rats with L V H . T h e s e f i n d i n g s s u g g e s t that both I B and a t t e n u a t i o n r e f l e c t the a m o u n t ot c o l l a g e n in h y p e r t r o p h i c ventricles. T h u s d e l i n e a t i o n o f structural r e m o d e l i n g o f m y o c a r d i a l ttssue b y u l t r a s o m c t i s s u e characterization permits assessment of altered material properties in left ventricular hypertrophy.
Conclusion: l) Translational velocities are greater than thickening velocities. 2) The mean left and right ventricular myocardial velocities are similar, but these are not similar in a given subject. 3) There is an association between peak systolic and diastolic myocardial velocities in a given wall in normals. 4) Absolute LVPW and RVFW diastolic (relaxation) velocities are greater than systolic velocities.
31D
ULTRASONIC TISSUE CHARACTERIZATION OF REMODELING IN LEFT VENTRICULAR HYPERTROPHY Victor G. D~vila-Rom~in, MD, Glenn E. Davison, MD, Christopher S. Hall, MS, James G. Millet, PhD, Samuel A. Wickline, MD Washington University School of Medicine, St. Louis, Missouri.
33D
INCREASED MYOCARDIAL CYCLIC VARIATION OF INTEGRATED BACKSCATTER AND OXYGEN CONSUMPTION IN PATIENTS WITH ISCHEMIC CARDIOMYOPATHY WITH INOTROPIC STIMULATION Victor G. D~ivila-Romfin, MD, Patficia J. Rubin, MD, Hiie M. Gnssak, MD, Julio E. Pdrez, MD, Robert L Gropler, M D Washington University School of Medicine, St. Louis, Missouri. It is well established that cyclic variation of integrated backseatter (CVIB) is not altered by inotropic stimulation in normal human myocardium. H o w e v e r , the response of C V I B to inotropic stimulation in mechanically dysfunctional myocardium is unknown. Accordingly, we m e a s u r e d CVIB at rest and during the administration of intravenous dobutamine (average 14 ug/kg/min) in nine patients, all males (average age 59 years) with ischemie cardiomyopathy. To ascertain whether changes in myocardial energy metabolism and mechanical function were associated with changes in CVIB, regional myocardial o x y g e n consumption (measured by positron emission tomography and C-11 acetate) and percent wall t h i c k e n i n g ( m e a s u r e d by t w o - d i m e n s i o n a l echocardiography) were obtained simultaneously. Measurements were performed in the proximal and mid-interventrieular septum and the proximal and mid-posterior wall (n = 29 paired segments). Under resting conditions CVIB averaged 1.4 _+0.3 dB and increased to 1.9 -+ 0.4, p < 0.005 during dobutamine stimulation. This change was paralleled by a 50% -+ I0%, (p < 0.0001) and a 39% -+ 14% (p = 0.0002) increase in myocardial oxygen consumption and percent wall thickening, respectively, compared with resting conditions. Thus, in contrast to normal myocardium, CVIB in mechanically dysfunctional m y o c a r d i u m can be a u g m e n t e d by inotropic stimulation. These changes are paralleled by increases in myocardial energy metabolism and mechanical function. The responsiveness of CVIB in this setting m a y have important implications for the use of this measurement in the detection of ischemic but viable myocardium.