Eur J Echocardiography (2006) 7, 293e297 What is a ‘‘normal’’ right ventricle? Sylva Kovalova*, Josef Necas, Jaroslav Vespalec Centre of Cardiovascular Surgery and Transplantation, Pekarska 53, 656 91 Brno, Czech Republic KEYWORDS Right ventricular volumetry; Right ventricular ejection fraction; 2D Echocardiography; Ellipsoidal shell model; Normal values Abstract Aims: The aim of this project was to define normal values of right ventricular (RV) volumes and ejection fraction (EF) in healthy population using 2D echocardiography. Methods and results: The ‘‘patient’’ group comprised 91 healthy volunteers aged 17e62 years. RV volumetry was based on ellipsoidal shell model method. Left ventricular (LV) volumes were assessed by Teichholz formula. All volumes were indexed per m2 of BSA and the rate distribution of measured and calculated values were evaluated. The normal range of individual parameters was expressed as mean value G 2 standard deviations (d). A pair test was used to compare corresponding results of the RV and LV measurements. The regression analysis was used to test the relationship between LV and RV volumes and age. Indexed enddiastolic and endsystolic RV volumes were 79.1 G 29.9 ml and 32.6 G 19.7 ml, respectively, EF being 50 G 9.7% in men and 58 G 13.6% in women. No correlation with patient’s age was observed. Conclusion: Enddiastolic and endsystolic volumes of RV were significantly higher than those of LV. EF of RV was lower as compare to LV. Right ventricular EF in men was lower than that in women. There was no correlation between EF and patient’s age. ª 2005 The European Society of Cardiology. Published by Elsevier Ltd. All rights reserved. Introduction In daily echocardiographical practice there is a need for exact quantification of right ventricular (RV) volumes (tricuspid and pulmonary regurgitation, interatrial shunts) as well as exact * Corresponding author. Tel.: C420 5431 82530; fax: C420 5432 11218. E-mail address: [email protected] (S. Kovalova). assessment of right ventricular ejection fraction (EF) (pulmonary hypertension, ischemic heart disease, cardiomyopathies). There are two major challenges: firstly, selection of the appropriate method and secondly, the interpretation of the results. At present several methods enable non-invasive quantification of RV volumes and EF (MRI,1e3 radionuclides4,5 and echocardiography6,7). There is a little experience in RV volumetry generally. 1525-2167/$32 ª 2005 The European Society of Cardiology. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.euje.2005.06.010 Downloaded from http://ehjcimaging.oxfordjournals.org/ by guest on September 30, 2014 Received 5 April 2005; received in revised form 6 June 2005; accepted 15 June 2005 Available online 19 July 2005 294 S. Kovalova et al. Figure 3 Distribution rate of indexed SVI of RV and LV in healthy population. Though MRI is considered the gold standard in RV volumetry,1e3 the selection of preferred method is influenced also by its availability, cost, patient’s comfort and repeatability during follow-up, therefore echocardiography might be preferred. Our experience as well as recent literature indicate that echocardiography is a relatively easy and reliable also in this respect.6,7 Concerning the interpretation of volumes and EF of the RV, there is still lack of generally accepted ‘‘normal’’ values and there is also a wide range variability of hitherto published data.1,4,5,8,9 The aim of our study was to answer the question e what are the ‘‘normal’’ values of volumes and EF of the right ventricle as assessed by 2D echocardiography. Right ventricular volumetry was accomplished using ‘‘ellipsoidal shell model’’ with corresponding formula V Z 2/3Pd. Area P was measured in our modification of apical four-chamber view and distance d in parasternal short axis. All measurements were performed in both systole and diastole. The difference of enddiastolic (EDV) and endsystolic volume (ESV) yielded stroke volume (SV). SV expressed as percentage of EDV represents RV EF. Exact specification of projections and validation of the model and method used was carried out on a group of 82 patients as published before.7 All measurements were performed on SONOS 5500 (Agilent Technologies, Inc., Andover, Massachussetts) using S3 probe in harmonic imaging mode. The patient group consisted of 91 healthy normotensive volunteers. Forty-six were men and 45 women with an average age of 39 years (range 17e62). All of them had a normal echocardiogram. Their respective RV volumes and EF were calculated as mentioned above. Left ventricular volumes were calculated using commercial software and Teichholz equation. All volumes were indexed per m2 of BSA. We analysed the distribution rate of all measured and calculated values as well as average values and median. ‘‘Normal range’’ was defined as mean value G 2d. Corresponding values of the right and left ventricles were compared using a pair Figure 2 Distribution rate of indexed ESV of RV and LV in healthy population. Figure 4 Distribution rate of EF of RV and LV in healthy population. Material and methods Downloaded from http://ehjcimaging.oxfordjournals.org/ by guest on September 30, 2014 Figure 1 Distribution rate of indexed EDV of RV and LV in healthy population. What is a ‘‘normal’’ right ventricle? 295 Table 1 Indexed volumes and EF of RV and LV in healthy population (mean value G 2 standard deviations) EDVI (ml/m2) ESVI (ml/m2) SVI (ml/m2) EF (%) Right ventricle Left ventricle 70.1 G 25.9 32.6 G 19.7 37.3 G 10.7 53.9 G 14.2 59.2 G 15.3 22.6 G 9.3 36.4 G 8.9 61.2 G 8.9 test. Statistical difference between right and left ventricular EF was tested by Student t-test. The correlation between the age and EF of respective RV and LV was tested by regression analysis. The distribution rate of values measured and calculated (indexed EDV, ESV, SV and EF) of the RV and LV approximately matches normal Gaussian distribution (Figs. 1e4). The indexed values of RV and LV volumes and EF are presented in Table 1. The indexed EDV (EDVI) and ESV (ESVI) of the RV were significantly greater than those of the LV (pair t-test, a Z 0.1%). There was no significant difference between indexed SV (SVI) of the RV and LV. This supports the validity of the RV volumetric method used. EF of the RV is significantly lower than that of the LV (pair t-test, a Z 0.1%). When comparing male and female patients, EDVI and ESVI of the RV in males exceed significantly those in females, which in turn explains the significantly lower RV EF in males as compare to females (Fig. 5). In contrast LV EF in both males and females did not show any significant difference (Table 2). RV and LV EF of the persons in our study were not dependent on the age (Fig. 6). Discussion Evaluation of the RV function based on quantitative volumetry is superior to semiquantitative Table 2 methods, however it requires solid methodology: exact projections and accuracy in measurements. Distribution of values of indexed ventricular volumes and EF in our study approached Gaussian curve, which is typical for biological measurements. Minor deviations from ideal shape can be explained by a relatively small number of persons in study and inherent inaccuracy of measurements. ‘‘Normal values’’ of RV1,4,5,8e10 and LV1,4,5,11e16 volumes and ejection fraction appear rarely in the literature. They usually are not the main aim of the studies, but only represent some smaller control groups evaluated by different methods. Therefore, the results are very inconsistent and vary widely. The ‘‘normal ranges’’ of averaged RV volumes and EF by different authors are shown in Table 3. Our results are within these ranges. Similar to our results, all studies comparing RV and LV volumetry by whichever method, found higher estimates for RV systolic and diastolic volumes than those of the LV.1,4,5 Systolic function of the ventricles is usually given as their EF. The estimation of EF in LV is a standard part of a routine echocardiographic examination. In our study group the lowest value of LV EF was 50%. Taking into account the accepted standard for normal values expressed as average value G 2 standard deviations, the LV EF in our study was 61.2 G 8.9%. The male subgroup did not Indexed volumes and EF of RV and LV in healthy men and women (mean value G 2 standard deviations) Men 2 EDVI (ml/m ) ESVI (ml/m2) SVI (ml/m2) EF (%) Women Right ventricle Left ventricle Right ventricle Left ventricle 78.9 G 19.7 39.5 G 15.0 39.4 G 9.1 50.0 G 9.7 61.8 G 14.9 24.0 G 10.0 37.7 G 8.4 60.7 G 8.4 60.8 G 17.2 25.6 G 12.7 35.2 G 10.7 58.0 G 13.6 56.5 G 13.8 21.2 G 7.7 35.2 G 8.9 61.7 G 9.4 Downloaded from http://ehjcimaging.oxfordjournals.org/ by guest on September 30, 2014 Results Figure 5 Distribution rate of EF of RV in healthy men and women. 296 S. Kovalova et al. a lower resting EF, which in fact represents functional reserve in a trained person. Exact explanation of the above relationship is beyond this study and would require another specifically aimed analysis. Study limitation Figure 6 Relation between EF of RV (LV) and age. Table 3 Indexed ventricular volumes and EF e range of mean values declared as ‘‘normal’’ by various authors 2 EDVI (ml/m ) ESVI (ml/m2) SVI (ml/m2) EF (%) ‘‘Normal’’ range Our measurements LV RV LV RV 52e87 14e35 18e52 59e74 63e103 22e56 40e41 43e65 59.17 22.64 36.42 61.20 70.0 32.6 37.31 53.91 Conclusions Enddiastolic and endsystolic RV volumes are greater than those of the LV, while RV EF is lower than that of LV. In our study the mean value of RV EF in males was lower than in females. Normal mean value of RV EF is 53.9%. The lower range in males is 40% and in females 45%. No relationship between RV EF and age in healthy individuals was found. References 1. Sechtem U, Pflugfelder P, Gould RG, Cassidy MM, Higgins ChB. Measurement of right and left ventricular volumes in healthy individuals with cine MR imaging. Radiology 1987;163:697e702. 2. Jauhiainen T, Jarvien VM, Hekali PE. Evaluation of methods for MR imaging of human right ventricular heart volumes and mass. Acta Radiol 2002;43(6):587e92. 3. Grothues F, Moon JC, Bellenger NG, Smith GS, Klein HU, Pennell D. Interstudy reproducibility of right ventricular volumes, function and mass with cardiovascular magnetic resonance. Am Heart J 2004;147(2):218e23. 4. Brynjolf I, Kelbaek H, Munck O, Godtfredsen J, Larsen S, Eriksen J, et al. Right and left ventricular ejection fraction and left ventricular volume changes at rest and during exercise in normal subjects. Eur Heart J 1984;5:756e61. 5. Kumar A, Anel R, Bunnell E, Habet K, Zanotti S, Marshall S, et al. Pulmonary artery occlusion pressure and central venous pressure fail to predict ventricular filling volume, cardiac performance, or the response to volume infusion in normal subjects. Crit Care Med 2004;32:691e9. 6. Denslow S, Wiles HB. Right ventricular volumes revisited: a simple model and simple formula for echocardiographic determination. J Am Soc Echocardiogr 1998;11:864e73. 7. Kovalova S, Necas J, Cerbak R, Malik P, Vespalec J. Echocardiography volumetry of the right ventricle. Eur J Echocardiogr 2005;6:15e23. Downloaded from http://ehjcimaging.oxfordjournals.org/ by guest on September 30, 2014 significantly differ from the female one (Table 2). These results correspond with the accepted normal range of LV EF, the lower range being 50e55%. There is a distinct difference in normal values of RV EF compared with the LV. The lowest value in our study group was 40%, the average value G 2d being 53.9 G 14.2. There was also a significant difference in RV EF between male and female subgroups (Table 2). To assume as the lower range of RV EF we suggest 40% for males and 45% for females. No explanation for this difference is known. In our study the average age of males was lower than that of females, but not significantly. Therefore, we also tested the relation of ventricular EF to the age. We did not observe any correlation of EF with patient’s age for either ventricle, although some authors declare slight tendency of decline of EF with age,17 others do not.18 Afterload is another potential factor influencing RV EF. Some authors showed decrease in RV EF under chronically increased afterload.19 We do not suspect increased pulmonary arterial pressure in healthy subjects of our study. Pulmonary arterial pressure rises during physical exertion. In our male subgroup over a half of the subjects used to exercise regularly at least twice a week, but none engaged in professional or endurance sports. In contrast to men, women were more sedentary and only a few of them exercised regularly. One may suggest that the RV (similarly to the LV) may react to the exercise by physiological dilatation and The main limitation is a relatively small study group. Increasing the data set would further refine the range of normal values of RV volumes and EF. Only indirect validation of the ellipsoidal shell model using SV determination by thermodilution has been accomplished. Our ‘‘normal’’ values might be valid only for the described method. What is a ‘‘normal’’ right ventricle? 14. Marcus JT, DeWaal LK, Gotte MJW, van der Geest RJ. MRIderived left ventricular function parameters and mass in healthy zuong adults: relation with gender and body size. Int J Cardiovasc Imag 1999;15:411e9. 15. Wahr DW, Wang ZS, Schiller NB. Left ventricular volumes determined by two-dimensional echocardiography in a normal adult population. J Am Cardiol 1983;3:863e8. 16. Correia LCL, Lakatta Eg, O’Connor C, Becker LC, Clulow J, Townsend S, et al. Attenuated cardiovascular reserve during prolonged submaximal cycle exercise in healthy older subjects. J Am Coll Cardiol 2002;40: 1290e7. 17. Slotwiner DJ, Devereux RB, Schwartz JE, Pickering TG, de Somine G, Ganau A, et al. Relation of age to left ventricular function in clinically normal adults. Am J Cardiol 1998;82: 621e6. 18. Sanstede J, Lipke C, Beer M, Hofman S, Pabst T, Kenn W, et al. Age- and gender-specific differences in left and right ventricular cardiac function and mass determined by cine magnetic resonance imaging. Eur Radiol 2000;10(3): 438e42. 19. Burger W, Jockwig B, Rucker G, Kober G. Influence of right ventricular pre- and afterload on right ventricular ejection fraction and preload recruitable stroke work relation. Clin Physiol 2001;1:85e92. Downloaded from http://ehjcimaging.oxfordjournals.org/ by guest on September 30, 2014 8. Van der Linden P, Gilbart E, Engelman E, de Rood M, Vincent JL. Determination of right ventricular volumes during aortic surgery. J Cardiothor Anesth 1989;3: 280e5. 9. Rapaport E, Wong M, Escobar EE, Martinez G. The effect of upright posture on right ventricular volumes in patients with and without heart failure. Am Heart J 1966;71: 146e52. 10. Burger W, Allroggen H, Kober G. Right ventricular volumes determined by computerized thermodilution in ischemic heart disease: effect of exercise and nitroglycerin. Int Cardiol 1991;33:233e42. 11. Kumar A, Anel R, Bunnell E, Habet K, Neuman A, Wolff D, et al. Effect of large volume infusion on left ventricular volumes, performance and contractility parameters in normal volunteers. Intensive Care Med 2004; 30:1361e9. 12. Masquet Ch, Slama MS, Dibie A, Sheehan FH, Lienard J. Normal left ventricular volumes and ejection fraction: assessment with quantitative digital cardioangiography. Int J Cardiovasc Imag 1998;14:27e36. 13. Wachspress JD, Clark NR, Untereker WJ, Kraushaar BT, Kurnik PB. Systolic and diastolic performance in normal human subject as measured by ultrafast computed tomography. Cathet Cardiovasc Diagn 1988;15:277e83. 297
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