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European Journal of Heart Failure 2007 9(1):62-67; doi:10.1016/j.ejheart.2006.04.009
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© 2007 European Society of Cardiology

Assessment of left ventricular asynchrony using volume—time curves of 16 segments by real-time 3 dimensional echocardiography: Comparison with tissue Doppler imaging

Seong-Mi Park, Ki-Chang Kim, Min-Jae Jeon, Chang-Kun Lee, Dae-Hyeok Kim, Keum-Soo Park, Woo-Hyung Lee and Jun Kwan*

Department of Cardiology, Inha University Hospital Incheon, South Korea

* Corresponding author. Department of Cardiology Inha University Hospital, 7-206, 3-Ga, Shinheung-Dong, Jung-Gu, Incheon, 400-711, South Korea. Tel.: +82 32 890 2453; fax: +82 32 890 2447. kuonmd{at}inha.ac.kr


   Abstract
Top
 Abstract
1. Introduction
 2. Methods
 3. Results
 4. Discussion
 References
 
Background: Recent technical developments with high-resolution real-time 3 dimensional echocardiography (RT3DE) facilitate the acquisition of high quality images and the analysis of segmental volume—time curves (VTCs).

Aims: To assess left ventricular (LV) asynchrony using the VTCs of 16 segments by RT3DE, and to evaluate accuracy compared to tissue Doppler imaging (TDI).

Methods: Twenty-three heart failure (HF) patients (LVEF: 25±6%, age: 60±13 years) and 16 normal controls underwent TDI and RT3DE. The standard deviation (SD3) of the end systolic time reaching minimal systolic volume for the 16 segments on VTCs was obtained by RT3DE. The standard deviation (SD2) of the electromechanical coupling time for the 8 segments was measured using TDI.

Results: SD3 was markedly higher in HF patients than in controls (7.7±2.5 vs 1.5±1.0%, P<0.01) and increased as LVEF decreased (r=–0.85, P<0.01). SD2 was also significantly higher in HF patients (27.0±8.6 vs 12.6±5.0 ms, P<0.01) and had a good negative correlation with LVEF (r=–0.72, P<0.01). SD3 was well correlated to SD2 (r=0.66, P<0.01).

Conclusions: We suggest that analysis of VTCs in 16 segments using RT3DE may be a useful alternative to TDI for the evaluation of LV asynchrony.

Key Words: Heart failure • Left ventricular asynchrony • Volume—time curves • Real-time 3 dimensional echocardiography • Tissue Doppler imaging

Received July 28, 2005; Revised January 23, 2006; Accepted April 10, 2006


   1. Introduction
Top
 Abstract
 1. Introduction
2. Methods
 3. Results
 4. Discussion
 References
 
Patients with left ventricular (LV) systolic dysfunction and dilation frequently have ventricular conduction delays and uncoordinated contraction, which is referred to as ventricular asynchrony [1]. LV asynchrony may contribute to disease progression in heart failure (HF) patients. The correction of ventricular asynchrony is an attractive treatment goal, and therefore methods for evaluating ventricular asynchrony are of great interest for the prognosis and therapeutic optimization of HF patients. It has recently been shown in the CARE-HF study that cardiac resynchronization therapy (CRT) not only improved symptoms and quality of life in heart failure patients with cardiac dyssynchrony, but also reduced complications and the risk of death [2].

QRS prolongation usually indicates impaired propagation of the electrical input, and is frequently associated with increased morbidity and mortality in HF patients [3,4]. However, recent data has demonstrated that mechanical asynchrony is not necessarily related to electrical asynchrony [5,6].

Thus, various non-invasive echocardiographic approaches have emerged for the assessment of mechanical asynchrony. Tissue Doppler echocardiography has been used in many studies and provides information on the location and the extent of mechanical LV asynchrony, which is impossible using QRS duration [7-9]. Recent technical developments permit the construction of a high-resolution real-time 3 dimensional echocardiography (RT3DE) transducer that allows the acquisition of high quality images from a single acoustic window. Moreover, phase analyses of segmental volume-time curves (VTCs) based on 3D data illustrate changes in regional myocardial motion and LV contraction patterns in an exact and quantitative way [10].

Therefore, the purposes of this study were to assess LV asynchrony in HF patients using the VTCs of 16 segments obtained by RT3DE and to evaluate accuracy compared to tissue Doppler imaging (TDI).


   2. Methods
Top
 Abstract
 1. Introduction
 2. Methods
3. Results
 4. Discussion
 References
 
2.1. Patients and controls
We performed 2D and 3D echocardiography in 28 consecutive HF patients and 17 healthy controls. Written informed consent was obtained from all subjects and the study was approved by the institutional review board of Inha University Hospital.

The inclusion criteria were as follows: 1) heart failure New York Heart Association (NYHA) class II or more for at least 12 months; 2) LV ejection fraction (LVEF) ≤35%, as assessed by echocardiography; 3) dilated cardiomyopathy with diffuse hypokinesia; and 4) stable medication (ACE inhibitors, β-blockers) for ≥3 months. Patients with acute coronary syndromes or who had undergone revascularization during the previous 6 months were excluded. Healthy controls had normal echocardiographic findings with LVEF ≥50% and did not have any symptoms of heart disease.

2.2. Standard two dimensional echocardiographic studies
All subjects were studied in the left lateral decubitus position using an ultrasound system equipped with tissue Doppler (Sonos 7500, Philips Medical Systems, Andover, Massachusetts) using a 3-MHz transducer. Standard two dimensional (2D) and M-mode echocardiograms were obtained, according to the American Society of Echocardiography guidelines [11]. Global LV function was assessed from two dimensional apical views by measuring LVEF, using the modified biplane Simpson rule [12].

2.3. Transthoracic RT3DE and the generation of volume-time curves
RT3DE scanning was performed using a commercially available system (Live 3D Echo, Phillips, Co.). RT3DE images were obtained from the apical window. Images for VTC analysis were gathered over four cardiac cycles using a matrix array ultrasonographic transducer. To generate the VTCs of the 16 segments over a complete cardiac cycle, measurements of 3D volumes of the 16 segments were performed offline using a 3D computer software (4D LV analysis, Tomtec Gmbh, Untersclessheim, Germany). Endocardial contours were marked in 6 slices (i.e., 30 degrees per slice) and contour tracing was performed using semi-automatic border detection following identification of the apex and mitral annulus on each slice, a pre-configured ellipse was fitted to the endocardial borders of each frame and adjusted as required (Fig. 1).


Figure 01
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  		Fig. 1 A) Semi-automatic endocardial border detection using real-time three dimensional echocardiography. B) LV cast generated by quantitative analysis in 16 segments. C,D) Regional volume-time curves (VTCs) in 16 segments in a normal control subject (C) and in a patient with heart failure (D).

 
2.4. Quantitative analysis of volume-time curves
LV end diastolic and end systolic volume (LVEDV and LVESV) were defined as the largest and smallest LV volumes through the cardiac cycle, respectively.

For quantitative analysis of volume changes during the cardiac cycle, the VTCs of the 16 segments were sampled and converted to Excel data at intervals of 1.02 ms (Fig. 1). End systolic time (EST) was defined as the time when the segmental volume reached end systolic volume on each VTC, and corrected EST (cEST) was obtained by adjustment according to heart rate.


Formula

The degree of LV asynchrony was determined from VTCs as the standard deviation of the cESTs (SD3) of the 16 segments.

2.5. Tissue Doppler imaging
TDI was obtained in pulsed-wave Doppler mode from the apical view to assess longitudinal myocardial regional function, to analyze the septal, lateral, anterior and inferior walls. The velocity profiles were recorded with a sample volume placed in the middle of the basal and mid segment of each wall. Gain and filters were adjusted as needed to eliminate background noise and to allow for a clear tissue signal. TDI signals were recorded at a sweep speed of 100 mm/s. From the Doppler spectrum, the electromechanical coupling time (EMT, defined as the time interval from the onset of the QRS complex on the surface ECG to the onset of the systolic TDI wave) was measured [13]. For the assessment of synchronicity, the standard deviation of the EMTs (SD2) for the 8 segments was calculated.

2.6. Statistical analysis
Data are presented as means±SD. Mann-Whitney testing was used to compare SD2 and SD3 for HF patients and normal controls. Linear regression analysis was performed to investigate correlations between parametric variables. All statistical analyses were performed using SPSS software (SPSS, Version 10.0, SPSS Inc). Statistical significance was defined at P<0.05.


   3. Results
Top
 Abstract
 1. Introduction
 2. Methods
 3. Results
4. Discussion
 References
 
3.1. Clinical baseline characteristics
Of the 28 HF patients and 17 controls, we had to exclude 5 HF patients and one normal control subject (13.3% of the total study population) due to suboptimal RT3DE image acquisition. 23 HF patients and 16 normal controls were included in the analysis (Table 1). Of the 23 HF patients, 5 (21.7%) had a history of multiple coronary artery stenoses. Five of the HF patients had a wide QRS complex (≥120 ms) on ECG., the remaining 18 patients had a normal QRS duration which was not significantly different from that of the controls (98±14 vs 91±14 ms, P=0.18).


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  		Table 1 Clinical characteristics of study population

 
In patients with HF, the mean LVEF was 25.0±5.6% and LV end diastolic diameter was 65.9±7.1 mm. The controls had normal values for these parameters which were assessed by 2D echocardiography (Table 2).


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  		Table 2 Two dimensional echocardiographic and tissue Doppler imaging parameters

 
3.2. Transthoracic RT3DE and the generation of volume-time curves
In accordance with 2D echocardiography findings, LVEDV and LVESV measured by RT3DE were larger in HF patients than in the controls. The ESTs of the 16 segments were more delayed and dispersed in HF patients than those of controls (Fig. 1 C,D). The mean cEST for 16 segments was significantly increased in HF patients compared to controls (47.7±6.9 vs 37.8±9.7%, P<0.05). SD3 was significantly larger in HF patients than controls (7.7±2.5 vs 1.5±1.0%, P<0.01, Table 3) and increased as LVEF decreased with a significant correlation (r=–0.85, P<0.01). Using a SD3 of >5% to define significant LV asynchrony, none was found in the control group, however 14 patients (77%) in the narrow QRS group and 4 patients (80%) in the wide QRS group showed significant LV asynchrony. Using a SD3 of >3.5% (+2 SD of normal controls) to define significant systolic asynchrony, identified 1 control subject (6%), 15 (83%) patients in the narrow QRS group and in 4 patients (80%) in the wide QRS group with significant systolic asynchrony.


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  		Table 3 Real-time 3 dimensional echocardiographic parameters

 
3.3. Tissue Doppler imaging
The mean EMTs of 8 segments were significantly higher in the HF patients than in the controls (P<0.05). SD2 was also significantly greater in the HF patients than in the controls (27.0±8.6 vs 12.6±5.0 ms, P<0.01, Table 2). SD2 had a good negative correlation with LVEF (r=–0.72, P<0.01). When a SD2 of >27 ms was used to define significant LV asynchrony, it was not found in the control group but was found in 9 (50%) patients in the narrow QRS group and in 3 (60%) in the wide QRS group. When a SD2 of >22.6 ms (+2 SD of normal controls) was used, it was present in only 1 (6%) control subject but in 13 (72%) patients in the narrow QRS group and in 4 (80%) in the wide QRS group.

3.4. Comparison between SD2 and SD3
There was a good correlation between SD2 and SD3 (r=0.66, P<0.01, Fig. 2). In patients with HF, the longest ESTs were distributed similarly from base to apex except for the anterior wall. The agreement of the walls between with longest EMT and EST in each patient was about 74% (17/23), and of the segments was 35% (8/23).


Figure 02
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  		Fig. 2 Correlation between SD3 and SD2 (r=0.66, P<0.01).

 

   4. Discussion
Top
 Abstract
 1. Introduction
 2. Methods
 3. Results
 4. Discussion
References
 
The results of this study show that myocardial wall motion can be quantified by volume-time curve analysis with 3D analysis software.

Coordinated LV contraction depends on normal ventricular activation. When the LV is composed of regions of both early and delayed contraction LV performance can be affected. Early or late shortening results in wasted work, a decrease in systolic performance, an increase in end systolic volume and wall stress, delayed relaxation, and a reduction in pumping efficiency [14,15].

In patients with HF and a wide QRS, signifying an electromechanical delay, cardiac resynchronization has been found to improve symptoms and quality of life and reduce complications and the risk of death [2,16,17]. However, despite careful patient selection, based on QRS complex duration some patients do not respond to CRT [18]. In addition, some patients with a wide QRS complex do not exhibit LV asynchrony, whereas others with a narrow QRS may demonstrate LV asynchrony [19,20]. Therefore, it is likely that surface ECG is not sensitive enough to detect the presence and severity of electromechanical delay resulting in asynchronous contraction. In the present study, the majority of patients with HF had a narrow QRS complex on ECG. and more than 50% of these patients had significant LV asynchrony. Therefore, irrespective of QRS duration, HF patients may have mechanical asynchrony. These results agreed well with those of other studies [19-21].

TDI provides much information, including the location and the severity of LV asynchrony [7,8]. However, TDI indices of asynchrony also have some limitations. Apart from active contraction, regional systolic velocities may reflect passive motion of segments due to heart motion or tethering by adjacent segments. It is difficult to measure myocardial velocities in the apical segments of the LV. Pulsed-wave TDI does not allow simultaneous comparisons of regional timing in different segments during a single beat, though this limitation may be reduced by colour-coded analysis. In addition, the longitudinal myocardial velocities are often very low in HF patients with severely decreased LV contractility.

RT3DE allows the acquisition of high quality images from a single acoustic window. Moreover, a computerized contour tracking algorithm has been developed that enables semi-automated data analysis with only minimal investigator involvement [22,23]. RT3DE allows precise evaluation of LV volumes, even in conditions of altered load [24] or distorted ventricular geometry. Phased analyses of segmental volume-time curves based on 3D data demonstrate changes in regional myocardial motion and LV contraction patterns in an exact and quantitative way and in contrast to TDI-based methods, all 16 segments of the LV can be evaluated using VTCs. Previous studies have demonstrated that volume-time curves, representing continuous LV volume changes, as determined by monitoring 16 segments throughout the cardiac cycle, allows more detailed quantitative analysis of LV performance, particularly in patients with asynergy [25,26].

RT3DE can provide a means of accurately and quantitatively analyzing dynamic LV volume changes in the whole LV chamber. The availability of VTCs in routine clinical practice would provide important clinical information about patients with impaired LV function, including information about asynchronous LV contraction. It is suggested that analysis of the VTCs of the 16 LV segments is an excellent means of assessing global LV performance and LV asynchrony. Several studies using RT3DE to evaluate CRT outcomes have recently been reported. Boudewijn J. et al. and Kapetanakis et al. used RT3DE for guiding and optimization of CRT [27,28], however, unlike our study, Kapetanakis et al. did not show a close correlation between TDI and RT3DE. In their study, the degree of LV synchrony measured by TDI did not have a good correlation with LV ejection fraction, which has been shown previously [8,19]. More than 50% of patients had ischaemic cardiomyopathy and a wide QRS complex, and patients with atrial fibrillation were included. It is possible that multiple other factors may also have affected the results. Therefore, further studies in larger numbers of patients are required to confirm our findings.

Despite the numerous advantages of RT3DE for evaluating LV asynchrony, it also has some limitations. First, it is more time consuming than TDI for the offline analysis of LV volume changes. Second, LV volume analysis is image size and quality dependent, thus clear endocardial border and complete LV cavity acquisition are required. Moreover, RT3DE has a lower temporal resolution than 2D echo. Nonetheless, the RT3DE frame rate of 15 to 24 frames/s in our study is sufficient to generate VTCs, previous studies for magnetic resonance imaging and electron beam tomography have used a frame rate of 16-20 frames/s [29,30].

In this study, agreement between the two methods was not complete. The possible causes of this discrepancy were, first, there might be unrecognized segments with TDI, especially apical segments. Second, the LV walls were divided differently for the TDI and RT3DE studies. Finally, since RT3DE has relatively lower temporal resolution than 2D echo, we may not have obtained true ESTs.

There were some limitations in this study. The study population was small and only 5 patients (21%) had a wide QRS complex. Compared to the results of other studies, this study showed that more than 60% of HF patients with a narrow QRS complex had significant LV asynchrony. This may be due to the small study population, much lower LVEF and the selection bias for patients.

In conclusion, the analysis of volume-time curves for the 16 LV segments using RT3DE may be a useful parameter for evaluating the presence of LV asynchrony and may provide detailed information about the 16 LV segments. However, further studies in large populations are required to confirm this methodology to assess LV asynchrony.


   References
Top
 Abstract
 1. Introduction
 2. Methods
 3. Results
 4. Discussion
 References
 

  1. Farwell D., Patel N.R., Hall A., Ralph S., Sulke A.N. How many people with heart failure are appropriate for biventricular resynchronization? Eur Heart J (2000) 21:1246–1250.[Abstract/Free Full Text]
  2. Cleland J.G.F., Daubert J., Erdmann E., Freemantle N., Gras D., Kappenberger L. Tavazzi L for the cardiac resynchronization — Heart Failure (CARE-HF) study investigators. The effect of cardiac resynchronization on morbidity and mortality in heart failure. N Engl J Med (2005) 352:1539–1549.[Abstract/Free Full Text]
  3. Likoff M.J., Chandler S.L., Kay H.R. Clinical determinants of mortality in chronic congestive heart failure secondary to idiopathic dilated or to ischemic cardiomyopathy. Am J Cardiol (1987) 59:634–638.[CrossRef][Web of Science][Medline]
  4. Silvet H., Padmanabham S., Pai R. Increased QRS duration reduces survival in patients with left ventricular dysfunction: results from a cohort of 2263 patients (abstr). J Am Coll Cardiol (1999) 33:146.[Abstract/Free Full Text]
  5. Leclercq C., Faris O., Tunin R., et al. Systolic improvement and mechanical resynchronization does not require electrical synchrony in the dilated failing heart with left bundle-branch block. Circulation (2002) 106:1760–1763.[Abstract/Free Full Text]
  6. Kass D.A. Predicting cardiac resynchronization response by QRS duration: the long and short of it. J Am Coll Cardiol (2003) 42:2125–2127.[Free Full Text]
  7. Ansalone G., Giannantoni P., Ricci R., et al. Doppler myocardial imaging to evaluate the effectiveness of pacing sites in patients receiving biventricular pacing. J Am Coll Cardiol (2002) 39:489–499.[Abstract/Free Full Text]
  8. Penicka M., Bartunek J., De Bruyne B., et al. Improvement of left ventricular function after cardiac resynchronization therapy is predicted by tissue Doppler imaging echocardiography. Circulation (2004) 109:978–983.[Abstract/Free Full Text]
  9. Lafitte Stephane, Garrigue Stephane, Perron Jean-Marie, et al. Improvement of left ventricular wall synchronization with multisite ventricular pacing in heart failure: a prospective study using Doppler tissue imaging. Eur J Heart Fail (2004) 6:203–212.[Abstract/Free Full Text]
  10. von Bardeleben R.S., Kuhl H.P., Mohr-Kahaly S., et al. Second-generation real-time three-dimensional echocardiography. Finally on its way into clinical cardiology? Z Kardiol (2004) 93(Suppl_4):56–64.[Web of Science]
  11. Schiller N.B., Shah P.M., Crawford M., et al. Recommendations for quantitation of the left ventricle by two-dimensional echocardiography. American Society of Echocardiography Committee on Standards, Subcommittee on Quantitation of Two-Dimensional Echocardiograms. J Am Soc Echocardiogr (1989) 2(5):358–367.[Medline]
  12. Stamm R.B., Carabello B.A., Mayers D.L., et al. Two-dimensional echocardiographic measurement of left ventricular ejection fraction: prospective analysis of what constitutes an adequate determination. Am Heart J (1982) 104:136–144.[CrossRef][Web of Science][Medline]
  13. Lane R.E., Chow A.W.C., Chin D., Mayet J. Selection and optimisation of biventricular pacing: the role of echocardiography. Heart (2004) 90:10–16.[Web of Science]
  14. Park R.C., Little W.C., O'Rourke R.A. Effect of alteration of left ventricular activation sequence on the left ventricular end-systolic pressure-volume relation in closed-chest dogs. Circ Res (1985) 57:706–717.[Abstract/Free Full Text]
  15. Heyndrickx G.R., Vantrimpont P.J., Rousseau M.F., et al. Effects of asynchrony on myocardial relaxation at rest and during exercise in conscious dogs. Am J Physiol (1988) 254:H817–H822.[Web of Science][Medline]
  16. Cazeau S., Leclercq C., Lavergne T., et al. Effects of multisite biventricular pacing in patients with heart failure and intraventricular conduction delay. N Engl J Med (2001) 344:873–880.[Abstract/Free Full Text]
  17. Kass D.A., Chen C.H., Curry C., et al. Improved left ventricular mechanics from acute VDD pacing in patients with dilated cardiomyopathy and ventricular conduction delay. Cir (1999) 99:1567–1573.
  18. Stellbrink C., Breithardt O.A., Franke A., et alon behalf of the PATH-CHF Investigators. Impact of cardiac resynchronization therapy using hemodynamically optimized pacing on left ventricular remodeling in patients with congestive heart failure and ventricular conduction disturbances. J Am Coll Cardiol (2001) 38:1957–1965.[Abstract/Free Full Text]
  19. Yu C.M., Lin H., Zhang Q. High prevalence of left ventricular systolic and diastolic asynchrony in patients with congestive heart failure and normal QRS duration. Heart (2003) 89:54–60.[Abstract/Free Full Text]
  20. Bleeker G.B., Schalij M.J., Molhoek S.G., et al. Relationship between QRS duration and left ventricular dyssynchrony in patients with end-stage heart failure. J Cardiovasc Electrophysiol (2004) 15:544–549.[Web of Science][Medline]
  21. Blazek G., Gessner M., Dornaus C., et al. Presence of left ventricular systolic asynchrony in patients with dilated cardiomyopathy: a selection criterium for biventricular pacing in congestive heart failure? Eur J Heart Fail (2000) 2(Suppl 1):36.[Free Full Text]
  22. Kuhl H.P., Schreckenberg M., Rulands D., et al. High-resolution transthoracic real-time three-dimensional echocardiography: quantitation of cardiac volumes and function using semi-automatic border detection and comparison with cardiac magnetic resonance imaging. J Am Coll Cardiol (2004) 43(11):2083–2090.[Abstract/Free Full Text]
  23. Jenkins C., Bricknell K., Hanekom L., et al. Reproducibility and accuracy of echocardiographic measurements of left ventricular parameters using real-time three-dimensional echocardiography. J Am Coll Cardiol (2004) 44(4):878–886.[Abstract/Free Full Text]
  24. Atkins B.Z., Kuo J., Shah A.S., et al. Real-time three-dimensional echocardiography to construct clinically ready, load-independent indices of myocardial contractile performance. J Am Soc Echocardiogr (2003) 16(9):922–930.[CrossRef][Web of Science][Medline]
  25. Zeidan Z., Erbel R., Barkhausen J., Hunold P., Bartel T., Buck T. Analysis of global systolic and diastolic left ventricular performance using volume-time curves by real-time three-dimensional echocardiography. J Am Soc Echocardiogr (2003) 16:29–37.[CrossRef][Web of Science][Medline]
  26. Hammermeister K.E., Brooks R.C., Warbasse J.R. The rate of change of left ventricular volume in man: II. Validation and peak systolic ejection rate in health and disease. Circulation (1974) 729–738.
  27. Krenning Boudewijn J., Szili-Torok Tamas, Voormolen Marco M., et al. Guiding and optimization of resynchronization therapy with dynamic three-dimensional echocardiography and segmental volume-time curves: a feasibility study. Eur J Heart Fail (2004) 6:619–625.[Abstract/Free Full Text]
  28. Kapetanakis S., Kearney M.T., Siva A., Gall N., Cooklin M., Monaghan M.J. Real-time three-dimensional echocardiography; a novel technique to quantify global left ventricular mechanical dyssynchrony. Cir (2005) 112:992–1000.[CrossRef]
  29. Soldo S.J., Norris S.L., Gober J.R., et al. MRI-derived ventricular volume curves for the assessment of left ventricular function. Magn Reson Imaging (1994) 12:711–717.[CrossRef][Web of Science][Medline]
  30. Rumberger J.A., Weiss R.M., Feiring A.J., Stanford W., Hajduczok Z.D. Patterns of regional diastolic function in the normal human left ventricle: an ultrafast computed tomographic study. J Am Coll Cardiol (1989) 14:119–126.[Abstract]

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