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A systematic approach to echocardiographic image acquisition and three-dimensional reconstruction using a subxiphoid rotational scan
384
Abstracts
35C
EFFECTS OF WALL STRESS AND LOADING CONDITIONS ON PHYSIOLOGIC HYPERTROPHY OF PREGNANCY Tal Geva, M.D., Mary Beth Mauer, R.N., B.S.N, Brian Kirshon, M.D., Jim Pivarnik PhD. Texas Children's Hospital and Baylor College of Medicine, Houston, Texas
Journal o f the American Society o f Echocardiography May-June 1995
37C
ANGIOGP.AI>HY Hope Johnson, Mary Corretti, M.D., Michael Fisher, M.D., Gary Plotnick, M.D. Department of Medicine, University of Maryland, Baltimore, MD
Pregnancy offers a unique physiologic model of transient increase in hemodynamic load associated with a reversible physiologic left ventricular hypertrophy (LVH). To examine the hypothesis that LV wall stress participates in the control mechanism(s) associated with acquisition and regression of LVH, 34 healthy women were studied by serial echo and Doppler exams at 6 time periods ( 10-12, 18-20, 28-30, 36-38 weeks gestation, 2-4 and 10-12 weeks postpartum). A total of 122 studies were performed (average: 3.6 studies/person). R e s u l t s : Compared to baseline, LV mass increased from I20.2_+13.7 g r m 160.5_+29.6 gr at late gestation (p=0.003) with return to normal by 10-12 weeks postpartuua. LV mass index increased from 73+6.9 to 88.5_+14.7 gr/m 2 (p=0.04). Peak systolic stress (PSS) was highest in early pregnancy (154.8_+44 gm/cm2), returning to normal by study 3 and 4 ( 121.7_+34 girdcm 2, p= 0.012). PSS increased in early pregnancy due to an increase in LV intemal dimensions without compensatory increase in wall thickness. Systolic, diastolic and mean blood pressure did not change significantly. The increase in LV mass followed the increase in PSS. At the same time, cardiac index (CI) increased rapidly reaching a peak by study 3 (32.2% increase front baseline, p=0.001), returning to normal by the 1~' postpartum exam, Parallel to the changes in CI, preload index increased 1.2 standard deviations (p=0.001), returning 1o baseline early postpartum. Endsystolic stress and total ejection stress decreased significantly during pregnancy without correlation to changes in LV m a s s C o n c l u s i o n s : 1, Rapid LV remodeling occurs during pregnancy in parallel to marked changes in hemodynmnic load. 2. The increase in LV mass follows an early surge in PSS, suggesting that peak LV wall stress may be part of the control mechanism responsible for physiologic hypertrophy of pregnancy.
36C
R E G R E S S I O N O F V E N T R I C U L A R H Y P E R T R O P H Y IS ASSOCIATED WITH PRESERVED VENTRICULAR F U N C T I O N : A S S E S S M E N T BY L O A D - I N D E P E N D E N T ECHOCARDIOGRAPHIC MEASUREMENTS Victor G. Dfivila-Rom~n, M D , Hiie M. Gussak, M D , Chris B a u m a n n , R D C S , Julio E. Pdrez, M D Washington University School o f Medicine, St. Louis, M O . Studies in animal m o d e l s of p r e s s u r e overload left ventriculm" hypertrophy ( L V H ) h a v e s h o w n a blunted contractile response to isoproterenol administration. W e h a v e previously s h o w n that patients with L V H due to h y p e r t e n s i o n ( H T N ) also exhibit a b l u n t e d c o n t r a c t i l e r e s e r v e to i n o t r o p i c s t i m u l a t i o n . T o d e t e r m i n e the effects o f reduction o f L V H on left ventricular function, w e m e a s u r e d L V m a s s i n d e x ( L V M I ) , e j e c t i o n f r a c t i o n (EF), v e l o c i t y o f c i r c u m f e r e n t i a l f i b e r s h o r t e n i n g (Vcfc) and end-systolic stress (ESS) at rest and during g r a d e d d o b u t a m i n e e c h o c a r d i o g r a p h y (5-40 g g / k g / m i n ) in 6 patients with H T N and L V H before and after one year o f treatment with felodipine (5-10 rag/d). After 1 yr o f felodipine treatment, the L V M I decreased significantly in all patients (116 + 7 vs 98 -+ 5 g / M 2 , p<0.005). The rest EF and V c f c increased in all patients (45 +3 vs 50 -+3 %, p = 0.03; 0.78 -+ 0.08 vs 0.93-+ 0.08 circ/sec, p=0.07, r e s p e c t i v e l y ) and all s h o w e d a n o r m a l r e s p o n s e to d o b u t a m i n e s t i m u l a t i o n ( i n c r e a s e d EF, V c f c , a n d no w a l l m o t i o n abnormalities). T h e c h a n g e in V c f c n o r m a l i z e d to the ESS (a load-independent index o f contractility) s h o w e d a small i m p r o v e m e n t at rest (1.3 -+ 0.23 vs 2.1 -+ 0.4 c i r c - c m 2 / g sec, p= 0.09; b e f o r e v s after treatment) but exhibited a flat r e s p o n s e d u r i n g d o b u t a m i n e stimulation in both studies (as p r e v i o u s l y s h o w n in L V H ) indicating blunted contractile reserve. Thus, i n t e r m e d i a t e - t e r m (1 yr) t r e a t m e n t w i t h a n t i h y p e r t e n s i v e m e d i c a t i o n c o n f e r s a s i g n i f i c a n t d e c r e a s e in L V H w i t h p r e s e r v a t i o n o f b a s e l i n e L V p e r f o r m a n c e , h o w e v e r the myocardial contractile reserve r e m a i n s limited.
V l E U A L ESTIMATE OF LEFT VENTRICULAR EJECTION FRACTION (LVEF) BY ECHOCARDIOGRAPHy: COMPARISON TO QUANTITATIVE ECHO METHOD8 AND RADIONUCLIDE
LVEF, a measure of systolic function, is prognostically important in patients with chronic heart failure (CHF). Several e c h o m e t h o d s t o a s s e s s LVEF have been e m p l o y e d . The objective of this study was to compare visual estimate of LVEF by two experienced echocardiographers (EYEBALL 1 and 2) with quantitative methods: Using endocardial border tracings from the 2-D apical image, a modified Simpson's rule (DISC METHOD) was used to calculate LVEF. M-mode tracings were used to measure and calculate mitral valve separation from the interventricular septum (EPSS), fractional shortening (FS) and EF by the cube formula (EF CUBE). Fifty CHF patients who had both radionuclide angiography (RNA) and echo within a 3 month period were evaluated. Echo m e a s u r e s w e r e c o m p a r e d with RNA. Mean RNA EF was 29 • 14% (range 6-74%). Correlation coefficients for echo measures compared to RNA EF were: EYEBALL 1 EYEBALL 2 DISC EPSS F S EF CUBE 0.74 0.79 0.50 -0.24 0.54 0.48 If only the 27 patients w~thout segmental wall motion abnormalities were assessed, r increased to 0.84 and 0.89 for EYEBALL 1 and 2. Visual estimate of LVEF by the eyeball method correlated better with RNA LVEF than a n y quantitative echo method. Visual estimate is rapid, experience dependent and clinically useful.
Poster Session D N e w Technologies 1D
A Systematic Approach to Echocardiographic Image Acquisition and ThreeDimensional Reconstruction Using a Subxiphoid Rotational Scan
John P,. Bates /riD, M. Victoria Tantengco MD, Thomas Ryan MD, Harvey Feigenbanm MD, Gregory J. EnsingMD, Indiana University, Indianapolis, IN Subxiphoid rotational scanning is an image acquisition technique used for threedimensional (3-DI echooardiograpby. Orieniation of the heart within the 3-D data set is not always apparent, making reconstruction complex and time consuming. The purpose of this study was to develop a systematic approach to image acquisition that facilitates 3-D reconstruction of traditional views and lesion-oriented renderings, specifically renderings of septation defects. The approach was developed during our initial experience in 12 sedated infants with congenital heart disease then successfully applied to 13 others. The final six studies were timed. Images were acquired with a transducer held in the subxiphoid position by a mechanical arm and interfaced with a TomTec computer. The transducer was aligned to display the long axis of the letl ventricle at zero degrees rotation. Images were acquired at one degree intervals through 180 degrees rotation and stored to the computer hard disc. Following post-processing, a reference image (RI) was selected from the 3-D data set that displayed the 2-D view at zero degrees rotation. To reconstruct 2-D short-axis images, cutting planes were positioned perpeudicalar to the long axis of the RI. To reconstruct traditional 2-D apical views, a central axis was defined by selecting points in the left ventricuiar apex and left atrium. Apical four-chamber, two-chamber and long-axis views were obtained by rotating cut planes about the central axis. Septation defects were identified in the 2-D short-axis images. Lesion-oriented renderings were derived by positioning a cut plane parallel to the defect from the chamber of interest and directing the line of site into the defect Dynamic 3-D renderings were obtained in all patients. The time (mean -+ S.D.) required for each step was: equipment set-up: 8.5 + 5.2; acquire and store images: 5.6 _+3.1; post-process data: 13.5 + 3.1; reconstruct short-axis images: 3.3 + 1.5; derive a lesion-oriented one-pixel rendering: 6.0 + 1.5 minutes. We conclude: 1) A systematic approach to image acquisition simplifies 3-D reconstruction. 2) Traditional views and lesion-oriented renderings can be derived using this technique. 3) The time required to reconstruct a 2-D image from which a dynamic 3-D rendering is derived was minimized. 4) Increasing the speed at which data is post-processed and the 3-D rendering is derived will further reduce the time necessary to perform 3-D echocardiography.
Abstracts
35C
EFFECTS OF WALL STRESS AND LOADING CONDITIONS ON PHYSIOLOGIC HYPERTROPHY OF PREGNANCY Tal Geva, M.D., Mary Beth Mauer, R.N., B.S.N, Brian Kirshon, M.D., Jim Pivarnik PhD. Texas Children's Hospital and Baylor College of Medicine, Houston, Texas
Journal o f the American Society o f Echocardiography May-June 1995
37C
ANGIOGP.AI>HY Hope Johnson, Mary Corretti, M.D., Michael Fisher, M.D., Gary Plotnick, M.D. Department of Medicine, University of Maryland, Baltimore, MD
Pregnancy offers a unique physiologic model of transient increase in hemodynamic load associated with a reversible physiologic left ventricular hypertrophy (LVH). To examine the hypothesis that LV wall stress participates in the control mechanism(s) associated with acquisition and regression of LVH, 34 healthy women were studied by serial echo and Doppler exams at 6 time periods ( 10-12, 18-20, 28-30, 36-38 weeks gestation, 2-4 and 10-12 weeks postpartum). A total of 122 studies were performed (average: 3.6 studies/person). R e s u l t s : Compared to baseline, LV mass increased from I20.2_+13.7 g r m 160.5_+29.6 gr at late gestation (p=0.003) with return to normal by 10-12 weeks postpartuua. LV mass index increased from 73+6.9 to 88.5_+14.7 gr/m 2 (p=0.04). Peak systolic stress (PSS) was highest in early pregnancy (154.8_+44 gm/cm2), returning to normal by study 3 and 4 ( 121.7_+34 girdcm 2, p= 0.012). PSS increased in early pregnancy due to an increase in LV intemal dimensions without compensatory increase in wall thickness. Systolic, diastolic and mean blood pressure did not change significantly. The increase in LV mass followed the increase in PSS. At the same time, cardiac index (CI) increased rapidly reaching a peak by study 3 (32.2% increase front baseline, p=0.001), returning to normal by the 1~' postpartum exam, Parallel to the changes in CI, preload index increased 1.2 standard deviations (p=0.001), returning 1o baseline early postpartum. Endsystolic stress and total ejection stress decreased significantly during pregnancy without correlation to changes in LV m a s s C o n c l u s i o n s : 1, Rapid LV remodeling occurs during pregnancy in parallel to marked changes in hemodynmnic load. 2. The increase in LV mass follows an early surge in PSS, suggesting that peak LV wall stress may be part of the control mechanism responsible for physiologic hypertrophy of pregnancy.
36C
R E G R E S S I O N O F V E N T R I C U L A R H Y P E R T R O P H Y IS ASSOCIATED WITH PRESERVED VENTRICULAR F U N C T I O N : A S S E S S M E N T BY L O A D - I N D E P E N D E N T ECHOCARDIOGRAPHIC MEASUREMENTS Victor G. Dfivila-Rom~n, M D , Hiie M. Gussak, M D , Chris B a u m a n n , R D C S , Julio E. Pdrez, M D Washington University School o f Medicine, St. Louis, M O . Studies in animal m o d e l s of p r e s s u r e overload left ventriculm" hypertrophy ( L V H ) h a v e s h o w n a blunted contractile response to isoproterenol administration. W e h a v e previously s h o w n that patients with L V H due to h y p e r t e n s i o n ( H T N ) also exhibit a b l u n t e d c o n t r a c t i l e r e s e r v e to i n o t r o p i c s t i m u l a t i o n . T o d e t e r m i n e the effects o f reduction o f L V H on left ventricular function, w e m e a s u r e d L V m a s s i n d e x ( L V M I ) , e j e c t i o n f r a c t i o n (EF), v e l o c i t y o f c i r c u m f e r e n t i a l f i b e r s h o r t e n i n g (Vcfc) and end-systolic stress (ESS) at rest and during g r a d e d d o b u t a m i n e e c h o c a r d i o g r a p h y (5-40 g g / k g / m i n ) in 6 patients with H T N and L V H before and after one year o f treatment with felodipine (5-10 rag/d). After 1 yr o f felodipine treatment, the L V M I decreased significantly in all patients (116 + 7 vs 98 -+ 5 g / M 2 , p<0.005). The rest EF and V c f c increased in all patients (45 +3 vs 50 -+3 %, p = 0.03; 0.78 -+ 0.08 vs 0.93-+ 0.08 circ/sec, p=0.07, r e s p e c t i v e l y ) and all s h o w e d a n o r m a l r e s p o n s e to d o b u t a m i n e s t i m u l a t i o n ( i n c r e a s e d EF, V c f c , a n d no w a l l m o t i o n abnormalities). T h e c h a n g e in V c f c n o r m a l i z e d to the ESS (a load-independent index o f contractility) s h o w e d a small i m p r o v e m e n t at rest (1.3 -+ 0.23 vs 2.1 -+ 0.4 c i r c - c m 2 / g sec, p= 0.09; b e f o r e v s after treatment) but exhibited a flat r e s p o n s e d u r i n g d o b u t a m i n e stimulation in both studies (as p r e v i o u s l y s h o w n in L V H ) indicating blunted contractile reserve. Thus, i n t e r m e d i a t e - t e r m (1 yr) t r e a t m e n t w i t h a n t i h y p e r t e n s i v e m e d i c a t i o n c o n f e r s a s i g n i f i c a n t d e c r e a s e in L V H w i t h p r e s e r v a t i o n o f b a s e l i n e L V p e r f o r m a n c e , h o w e v e r the myocardial contractile reserve r e m a i n s limited.
V l E U A L ESTIMATE OF LEFT VENTRICULAR EJECTION FRACTION (LVEF) BY ECHOCARDIOGRAPHy: COMPARISON TO QUANTITATIVE ECHO METHOD8 AND RADIONUCLIDE
LVEF, a measure of systolic function, is prognostically important in patients with chronic heart failure (CHF). Several e c h o m e t h o d s t o a s s e s s LVEF have been e m p l o y e d . The objective of this study was to compare visual estimate of LVEF by two experienced echocardiographers (EYEBALL 1 and 2) with quantitative methods: Using endocardial border tracings from the 2-D apical image, a modified Simpson's rule (DISC METHOD) was used to calculate LVEF. M-mode tracings were used to measure and calculate mitral valve separation from the interventricular septum (EPSS), fractional shortening (FS) and EF by the cube formula (EF CUBE). Fifty CHF patients who had both radionuclide angiography (RNA) and echo within a 3 month period were evaluated. Echo m e a s u r e s w e r e c o m p a r e d with RNA. Mean RNA EF was 29 • 14% (range 6-74%). Correlation coefficients for echo measures compared to RNA EF were: EYEBALL 1 EYEBALL 2 DISC EPSS F S EF CUBE 0.74 0.79 0.50 -0.24 0.54 0.48 If only the 27 patients w~thout segmental wall motion abnormalities were assessed, r increased to 0.84 and 0.89 for EYEBALL 1 and 2. Visual estimate of LVEF by the eyeball method correlated better with RNA LVEF than a n y quantitative echo method. Visual estimate is rapid, experience dependent and clinically useful.
Poster Session D N e w Technologies 1D
A Systematic Approach to Echocardiographic Image Acquisition and ThreeDimensional Reconstruction Using a Subxiphoid Rotational Scan
John P,. Bates /riD, M. Victoria Tantengco MD, Thomas Ryan MD, Harvey Feigenbanm MD, Gregory J. EnsingMD, Indiana University, Indianapolis, IN Subxiphoid rotational scanning is an image acquisition technique used for threedimensional (3-DI echooardiograpby. Orieniation of the heart within the 3-D data set is not always apparent, making reconstruction complex and time consuming. The purpose of this study was to develop a systematic approach to image acquisition that facilitates 3-D reconstruction of traditional views and lesion-oriented renderings, specifically renderings of septation defects. The approach was developed during our initial experience in 12 sedated infants with congenital heart disease then successfully applied to 13 others. The final six studies were timed. Images were acquired with a transducer held in the subxiphoid position by a mechanical arm and interfaced with a TomTec computer. The transducer was aligned to display the long axis of the letl ventricle at zero degrees rotation. Images were acquired at one degree intervals through 180 degrees rotation and stored to the computer hard disc. Following post-processing, a reference image (RI) was selected from the 3-D data set that displayed the 2-D view at zero degrees rotation. To reconstruct 2-D short-axis images, cutting planes were positioned perpeudicalar to the long axis of the RI. To reconstruct traditional 2-D apical views, a central axis was defined by selecting points in the left ventricuiar apex and left atrium. Apical four-chamber, two-chamber and long-axis views were obtained by rotating cut planes about the central axis. Septation defects were identified in the 2-D short-axis images. Lesion-oriented renderings were derived by positioning a cut plane parallel to the defect from the chamber of interest and directing the line of site into the defect Dynamic 3-D renderings were obtained in all patients. The time (mean -+ S.D.) required for each step was: equipment set-up: 8.5 + 5.2; acquire and store images: 5.6 _+3.1; post-process data: 13.5 + 3.1; reconstruct short-axis images: 3.3 + 1.5; derive a lesion-oriented one-pixel rendering: 6.0 + 1.5 minutes. We conclude: 1) A systematic approach to image acquisition simplifies 3-D reconstruction. 2) Traditional views and lesion-oriented renderings can be derived using this technique. 3) The time required to reconstruct a 2-D image from which a dynamic 3-D rendering is derived was minimized. 4) Increasing the speed at which data is post-processed and the 3-D rendering is derived will further reduce the time necessary to perform 3-D echocardiography.