Echocardiographic Assessment of Right Ventricular Systolic Function: A 2D, Anatomical, and Conventional M-Mode Comparison Study

Arezou Zoroufian; Hossein Sate; Masoumeh Lotfi-Tokaldany; Mohammad Sahebjam; Hakimeh Sadeghian; Arash Jalali

doi:10.5812/acvi.37901

Echocardiographic Assessment of Right Ventricular Systolic Function: A 2D, Anatomical, and Conventional M-Mode Comparison Study

Arezou Zoroufian ¹ , Hossein Sate ^{1
, 2
, *} , Masoumeh Lotfi-Tokaldany ¹ , Mohammad Sahebjam ¹ , Hakimeh Sadeghian ¹ and Arash Jalali ¹

Authors Information

Article Notes and Dates

To Cite : Zoroufian A, Sate H, Lotfi-Tokaldany M, Sahebjam M, Sadeghian H, et al. Echocardiographic Assessment of Right Ventricular Systolic Function: A 2D, Anatomical, and Conventional M-Mode Comparison Study, Arch Cardiovasc Imaging. 2016 ;4(4):e37901. doi: 10.5812/acvi.37901.

Abstract

Results: The mean age of the patients was 53.27 ± 14.29 years and 52.9% were male. The patients were mostly diagnosed as having left-sided valvular disease in terms of mitral stenosis, mitral regurgitation, aortic stenosis, or aortic regurgitation (63 patients, 41.4%). Heart failure was in 18.4% and coronary artery disease in 15.8%. Among 152 patients, 17 (11.2%) had normal findings in echocardiography. Concerning RV-FAC, we categorized the patients into 3 groups: 116 patients with RV-FAC equal to or greater than 35%, 24 patients with RV-FAC between 35% and 25%, and 12 patients with RV-FAC equal to or smaller than 25%. To discriminate normal from abnormal RV-FACs (≥ 35% vs < 35%), TAPSE by AMM had specificity of 96.5% and sensitivity of 60.5% (P < 0.001) for a cutoff point of 19.5 mm to separate the patients with RV-FAC equal to or greater than 35% from those with RV-FAC smaller than 35%. TAPSE by CMM had similar specificity and sensitivity (98.5% and 53.8%, respectively [P < 0.001]) for a cutoff point of 17.5 mm.

1. Background

Systolic right ventricular (RV) volume and function is an important tool to predict cardiac events, exercise capacity, and mortality in patients with symptomatic heart failure, significant lung disease, congenital heart disease, and heart transplantation (1-5). Therefore, it is important to evaluate RV function accurately. However, the echocardiographic evaluation of RV function is limited because of the complex geometrical shape of the RV and difficulty in obtaining good quality images of it. Although short-axis cine sequences have become the gold standard for RV function assessment (6, 7), it is costly and not widely available. Right ventricular fractional area change (RV-FAC), measured by 2D echocardiography, is traditionally used for the reliable assessment of RV systolic function. It has been documented that RV-FAC is the best of the commonly utilized measures of 2D echocardiography for RV function and has the best correlation (r = 0.80) with magnetic resonance imaging (MRI)-derived RV ejection fraction (8, 9). The Simpson estimated RV ejection fraction, myocardial performance index, and tricuspid annular plane systolic excursion (TAPSE) are other echocardiographic measures to estimate RV systolic or global function, but each has its own limitations. Among them, TAPSE measured by M-mode is the most commonly used technique and because of its simplicity and reproducibility, it is recommended by the guidelines of the American Society of Echocardiography (ASE) as a part of routine echocardiographic evaluation. The major limitation of TAPSE is the fact that it has a 1D nature and it is difficult to perfectly align the ultrasound beam with the direction of the tricuspid annular motion at the free wall, resulting in the underestimation of the annular displacement.

In contrast, the anatomical M-mode (AMM) technique allows not only the capture of M-mode images by orientating the analysis line in any direction but also a free orientation of the analysis line by perfectly aligning it to the ventricle axis in every echocardiographic approach in spite of morpho-volumetric variability (10-12).

We hypothesized that measuring TAPSE by AMM might be better correlated with RV-FAC than TAPSE measured by conventional M-mode (CMM). Therefore, in this study we aimed to compare TAPSE by AMM and CMM with RV-FAC for the evaluation of RV systolic function.

2. Methods

2.1. Study Population

This descriptive cross-sectional study was carried out in the Echocardiography Department of Tehran heart center, Tehran, Iran. Between February 2013 and February 2014, 152 patients, who were referred for the evaluation of cardiac function, were prospectively enrolled in the study. Patients with atrial fibrillation and right-sided volume overload (caused by large atrial septal defects or severe pulmonary valve insufficiency) were excluded from the study. All the patients underwent CMM and 2D echocardiography and AMM echocardiography. The study protocol was approved by our institutional review board.

2.2. Transthoracic 2D, M-Mode, and Pulsed Doppler Echocardiography

All the subjects were examined in the supine, left lateral decubitus position using a System 7 Digital Ultrasound Machine (General Electric Ultrasound, Horten, Norway) with a 2.5- or 3.5-MHz phased-array transducer, with the machine being operated by a single experienced echocardiographer. The measurements of the dimensions and volumes of the left ventricle (LV) and the RV were performed according to the recommendations of the ASE (13, 14)

2.3. Right Ventricular Measurements

Each value was an average of 3 measurements obtained from 3 cardiac cycles.

RV-FAC was obtained in the 4-chamber view via the following formula (15):

FAC = (end-diastolic area - end-systolic area)/(end-diastolic area) × 100

TAPSE for the RV free wall (mm) was determined by CMM and AMM echocardiography (Figure 1) as the distance between the basal, end-diastolic position of the tricuspid annulus at the beginning of the QRS complex in the surface ECG and its greatest apical long-axis movement (16). RV pulsed-wave of the peak systolic tricuspid annular motion velocity at the lateral free wall (RV-Sm, cm/s) was obtained from the apical 4-chamber view 15 using tissue Doppler imaging. The strain in the lateral wall (RV strain, %) was obtained using tissue Doppler imaging in the 4-chamber view (17).

Figure 1. Measurement of the Right Ventricular Free Wall Using A, Anatomical M-Mode; B, Conventional M-Mode; and C, Pulsed-Wave Tissue Doppler Imaging Methods.

2.4. Measurement by Anatomical M-Mode

AMM images were obtained by digital reconstruction from 2D stored cineloop images (Vivid 7 Dimension, GE, Horten, Norway). A freely mobile virtual M-mode line was positioned in the basal portion of the RV free wall at the level of the tricuspid valve annular plane to the longitudinal axis of the RV in the apical images with all efforts to obtain optimal alignment of the M-mode cursor line over the RV apex similar to that seen in CMM (Figure 1). Measurements were made of the height of the maximal longitudinal displacement of the RV basal potion toward the apex during systole.

2.5. Reproducibility

Intraobserver variability for RV-FAC by CMM and AMM and RV-Sm and RV strain was obtained in 5 randomly selected individuals over the entire range of RV-FAC. The measurements were repeated offline by the same observer at a 2-week interval from the 1st measurement.

2.6. Statistical Analysis

The normality distribution of the continuous data was checked using the Shapiro-Wilk test. For comparison between groups of continuous variables, analysis of variance (ANOVA) was utilized (Bonferroni test for post hoc analysis). The categorical parameters were analyzed using the χ² test or the Fisher exact test. Linear regression analysis was carried out for the detection of statistically relevant correlations between CMM and AMM echocardiography and RV-FAC (as the reference method). The correlations between the measurements were tested using the Pearson correlation test. The receiver operating characteristic (ROC) analysis was performed with the study parameters as the test variables and RV-FAC. Intraobserver variability was calculated.

For the statistical analyses, the statistical software SPSS, version 20.0, for Windows (SPSS Inc., Chicago, IL) was employed. All the P values were 2-tailed, with statistical significance defined by a P value equal to or smaller than 0.05.

3. Results

The mean age of the patients was 53.27 ± 14.29 years, and 52.9% were male. The demographic and clinical characteristics of the study patients are summarized in Table 1. The patients were mostly diagnosed as having left-sided valvular disease in terms of mitral stenosis, mitral regurgitation, aortic stenosis, or aortic regurgitation (63 patients, 41.4%). Heart failure (LV ejection fraction < 40%) was detected in 18.4% and coronary artery disease in 15.8%. Among 152 patients, 17 (11.2%) had normal findings in echocardiography. According to 2D echocardiography, the mean RV-FAC was 40.76 ± 9.89%. The mean value for TAPSE by CMM was 20.29 ± 3.80 and by AMM was 22.66 ± 4.61. The measurement of TAPSE by AMM was significantly higher than that by CMM (P < 0.001).

Table 1. Demographic and Clinical Characteristics of the Study Population^a

Variables	Statistics
Mean age	53.36 ± 14.22
Female/male	73/79
Body mass index, kg/m²	26.28 ± 4.80
Body surface area, m²	1.81 ± 0.21
Diabetes mellitus	15 (9.9)
Hypertension	17 (11.2)
Hyperlipidemia	10 (6.6)
Cigarette smoking	3 (2.0)
Diagnosis
Left-sided valve disease	63 (41.4)
Right-sided valve disease	1 (0.7)
Atrial septal defect	12 (7.9)
Coronary artery disease	24 (15.8)
Heart failure	28 (18.4)
Patent foramen ovale	5 (3.3)
Coarctation of the aorta	1 (0.7)
Ventricular septal defect	1 (0.7)
Normal	17 (11.2)

^aValues are expressed as mean ± SD or No. (%).

In terms of RV-FAC, we categorized the patients into 3 groups: 116 patients with RV-FAC equal to or greater than 35%, 24 patients with RV-FAC between 35% and 25%, and 12 patients with RV-FAC equal to or smaller than 25%. The demographic and 2D echocardiographic findings are compared between these 3 groups in Table 2. Moderate or severe tricuspid regurgitation occurred in 19.8% (23/116) of the patients in the group with RV-FAC equal to or greater than 35%, 41.7% (10/24) in the group with RV-FAC between 25% and 35% group, and 41.7% (5/12) in the group with RV-FAC equal to or smaller than 25% (P = 0.030). RV-Sm, RV peak systolic strain, and TAPSE by conventional 2D echocardiography and TAPSE by AMM differed significantly between the groups (Table 2). These parameters correlated linearly and significantly with the reference parameter of RV-FAC (Figure 2).

Table 2. 2D Echocardiographic Findings in the 3 Groups According to the RV-FAC Categories^a

	RV-FAC > 35%	RV-FAC 25% - 35%	RV-FAC < 25%	P Value
Age, y	51.57 ± 13.96	58.25 ± 13.97	58.75±14.83	0.049
Men	58 (50)	14 (58.3)	7 (58.3)	0.682
Body mass index, kg/m²	26.45 ± 4.85	26.76 ± 5.33	23.64 ± 1.91	0.735
Body surface area, m²	1.82 ± 0.20	1.80 ± 0.26	1.77 ± 0.16	0.715
LV ejection fraction, %	55 (50, 55)	50 (30, 55)	32 (25, 32)	< 0.001
LV end-systolic diameter, mm	31.5 (27, 37)	41 (26, 48)	45 (36, 58)	0.003
LV end-diastolic diameter, mm	50 (45, 55)	44 (57, 62)	59 (47, 70)	0.040
Systolic pulmonary artery pressure, mm Hg	37 (30, 44)	45 (37, 56)	43 (33, 82)	0.002
Tricuspid regurgitation peak pressure gradient, mm Hg	26 (21, 33)	35 (29, 46)	33 (28, 67)	< 0.001
RV diameter, mm	30.42 ± 4.74	32.17 ± 5.33	35.17 ± 8.28	0.007
Tricuspid valve annulus, mm	29.70 ± 4.46	30.67 ± 6.25	34.08 ± 6.50	0.014
Tricuspid regurgitation ≥ moderate	23 (19.8)	10 (41.7)	5 (41.7)	0.014
RV free-wall peak systolic velocity, m/s	11.93 ± 1.90	10.08 ± 2.54	7.75± 1.48	<0.001
RV free-wall peak systolic strain, %	25.13 ± 4.70	18.86 ± 6.33	13.75 ± 3.25	< 0.001
TAPSE by CMM, mm	21.26 ± 2.82	18.86 ± 4.51	13.83 ± 3.38	< 0.001
TAPSE by AMM, mm	23.93 ± 3.12	20.57 ± 6.01	14.33 ± 3.67	< 0.001

Abbreviations: AMM, Anatomical M-mode; CMM, Conventional M-mode; FAC, Fractional area change; LV, Left ventricle; RV, Right ventricle; TAPSE, Tricuspid annular plane systolic excursion.

^aValues are expressed as mean ± SD or or median (25th and 75th percentiles).

Figure 2. Correlation in all the study patients between RV fractional area changes as obtained by 2D echocardiography and A, RV-Sm; B, RV peak systolic strain; C, TAPSE by conventional 2D echocardiography; and D, TAPSE by AMM

RV, Right ventricle; RV-Sm, Right ventricular pulsed-wave of the peak systolic tricuspid annular motion velocity at the lateral free wall; TAPSE, Tricuspid annular plane systolic excursion; AMM, Anatomical M-mode.

To discriminate normal from abnormal RV-FACs (≥ 35% vs < 35%), a cutoff point of 19.5 mm using TAPSE by AMM had specificity of 96.5% and sensitivity of 60.5% (area under the curve = 72.3, 95% CI: 60.9 to 83.7; P < 0.001). A cutoff point of 17.5 mm using TAPSE by CMM had slightly higher specificity (98.5%) but lower sensitivity (53.8%) than TAPSE by AMM (area under the curve = 74.7, 95% CI: 63.1 to 86.3; P < 0.001).

4. Discussion

The results of the present study on patients with different cardiovascular diseases showed that TAPSE by AMM was comparable to TAPSE by CMM echocardiography with a good correlation with normal and abnormal RV functions based on RV-FAC.

The evaluation of RV function is one of the challenging issues in the field of echocardiography. MRI has become the technique of choice to assess RV function because it allows accurate volumetric assessment of RV volumes, ejection fraction, and mass. However, MRI has several limitations such as relatively limited temporal resolution, time-consuming data acquisition and analysis, high costs, limited availability of MRI facilities, and lack of trained personnel, as well as the technical limitations of MRI at the relatively limited time available. In contrast, conventional echocardiography is a simple bedside tool, although determining RV ejection fraction by 2D echocardiography is difficult due to its complex shape, precluding its visualization in any single 2D echocardiographic view.

Considering the fact that it is possible to completely evaluate the heart by 2D echocardiography in our daily clinical practice , CMM echocardiography is still used for the measurement of LV sizes and function and RV function (as TAPSE evaluation ) because this mode has a good temporal resolution that can increase the identification of the heart’s borders. Nonetheless, there are several limitations regarding CMM study such as beam alignment. Indeed, the beam should be aligned to the longitudinal axis for accurate measurement and sometimes it might not be obtained at all or sometimes there is a single fixed beam that restricts M-mode line and the spatial resolution.

AMM (or virtual M-mode) is an offline post processing technique that is available in the Vingmed (Horten, Norway) systems with some advantages in relation to the CMM technique like the ability to freely move the cursor line and read the 2D pixels along the selected M-mode line in digitally stored cineloops. This can be updated through the cardiac cycle and overcome the effects of cardiac translation or twist. Additionally, it confers the highest 2D ultrasound frame rate (up to 50 - 60 Hz) (18). None of the previous studies has focused on the possibility of evaluating RV function by AMM, and the accuracy of this method has not been compared with the currently widely used methods in the routine practice. Therefore, for the 1st time, we evaluated RV global systolic function by measuring TAPSE via AMM echocardiography.

The 1st experience with this technique was reported by Pierard et al. (19) and the 2nd one by Mele et al. (20) In both studies, the reproducibility of LV measurements by AMM was higher than that by CMM. In the present study, we also observed that for evaluating RV function, the mean value for TAPSE by AMM was significantly higher than that by CMM (22.66 ± 4.61 vs 20.29 ± 3.80, respectively).

RV-FAC is a 2D assessment that correlates well with RV ejection fraction, determined by volumetric analysis using cardiac MRI. In the present study, we assessed the accuracy of TAPSE measured by AMM in a group of patients with different levels of RV dysfunction based on RV-FAC. We observed that a cutoff point of 19.5 mm for TAPSE by AMM had specificity of 96.5% to separate normal from abnormal RV functions. This specificity was close to the specificity that was detected for CMM in this study (98.2% for the cutoff point of 17.5 mm). Both techniques had also similar specificity for discriminating a normal RV function.

4.1. Study Limitations

One of the most important limitations in this study is the use of FAC as a reference for evaluating RV function, while we are aware that cardiac MRI is currently the gold-standard method to quantify RV global function. Another drawback of note is that the number of patients with RV-FAC smaller than 25% was small, precluding a reliable analysis to investigate the accuracy of AMM in detecting different levels of RV dysfunction. In addition, we did not include an age and sex-matched control group.

4.2. Conclusions

In the present study, we included evaluation of RV global systolic function by AMM echocardiography to the previously introduced methods. The results of the current study on patients with a variety of cardiovascular diseases showed that TAPSE by AMM compared to TAPSE by CMM echocardiography had similar accuracy in distinguishing normal from abnormal RV functions based on RV-FAC.

4.3. Implications

The results of present study on patients with a variety of cardiovascular diseases revealed that AMM could be used for the evaluation of RV function in that it was able to accurately discriminate normal from abnormal RV functions based on RV-FAC. This study may pave the way for designing further studies aimed at proving the valuable role of AMM echocardiography in the routine practice.

Footnote

References

1. Di Salvo TG, Mathier M, Semigran MJ, Dec GW. Preserved right ventricular ejection fraction predicts exercise capacity and survival in advanced heart failure. J Am Coll Cardiol. 1995; 25(5): 1143-53[PubMed]
2. Ghio S, Recusani F, Klersy C, Sebastiani R, Laudisa ML, Campana C, et al. Prognostic usefulness of the tricuspid annular plane systolic excursion in patients with congestive heart failure secondary to idiopathic or ischemic dilated cardiomyopathy. Am J Cardiol. 2000; 85(7): 837-42[DOI]
3. Alpendurada F, Guha K, Sharma R, Ismail TF, Clifford A, Banya W, et al. Right ventricular dysfunction is a predictor of non-response and clinical outcome following cardiac resynchronization therapy. J Cardiovasc Magn Reson. 2011; 13: 68[DOI][PubMed]
4. Piran S, Veldtman G, Siu S, Webb GD, Liu PP. Heart failure and ventricular dysfunction in patients with single or systemic right ventricles. Circulation. 2002; 105(10): 1189-94[PubMed]
5. Ghio S, Klersy C, Magrini G, D'Armini AM, Scelsi L, Raineri C, et al. Prognostic relevance of the echocardiographic assessment of right ventricular function in patients with idiopathic pulmonary arterial hypertension. Int J Cardiol. 2010; 140(3): 272-8[DOI][PubMed]
6. Maceira AM, Prasad SK, Khan M, Pennell DJ. Reference right ventricular systolic and diastolic function normalized to age, gender and body surface area from steady-state free precession cardiovascular magnetic resonance. Eur Heart J. 2006; 27(23): 2879-88[DOI][PubMed]
7. American College of Cardiology Foundation Task Force on Expert Consensus D, Hundley WG, Bluemke DA, Finn JP, Flamm SD, Fogel MA, et al. ACCF/ACR/AHA/NASCI/SCMR 2010 expert consensus document on cardiovascular magnetic resonance: a report of the American College of Cardiology Foundation Task Force on Expert Consensus Documents. Circulation. 2010; 121(22): 2462-508[DOI][PubMed]
8. Anavekar NS, Gerson D, Skali H, Kwong RY, Yucel EK, Solomon SD. Two-dimensional assessment of right ventricular function: an echocardiographic-MRI correlative study. Echocardiography. 2007; 24(5): 452-6[DOI][PubMed]
9. Lai WW, Gauvreau K, Rivera ES, Saleeb S, Powell AJ, Geva T. Accuracy of guideline recommendations for two-dimensional quantification of the right ventricle by echocardiography. Int J Cardiovasc Imaging. 2008; 24(7): 691-8[DOI][PubMed]
10. Abadi C, Alvear E, Mockizuki Y. Digital anatomic M-mode yelds more accurate and reproducible measurement of ventricular dimension and fractional shortenings than conventional M-mode, with greater versality. An advantage of a new, fully digital echo system. J Am Soc Echocardiograph. 1998; 11: 529
11. Carerj S, Micari A, Trono A, Giordano G, Cerrito M, Zito C, et al. Anatomical M-mode: an old-new technique. Echocardiography. 2003; 20(4): 357-61[PubMed]
12. Mele D, Trono A. ["Anatomical M-mode": a new echocardiographic technique potentially useful in the quantitative study of the left ventricle]. Cardiologia. 1998; 43(7): 701-10[PubMed]
13. Sahn DJ, DeMaria A, Kisslo J, Weyman A. Recommendations regarding quantitation in M-mode echocardiography: results of a survey of echocardiographic measurements. Circulation. 1978; 58(6): 1072-83[PubMed]
14. Lang RM, Bierig M, Devereux RB, Flachskampf FA, Foster E, Pellikka PA, et al. Recommendations for chamber quantification. Eur Heart J Cardiovasc Imag. 2006; 7(2): 79-108
15. Rudski LG, Lai WW, Afilalo J, Hua L, Handschumacher MD, Chandrasekaran K, et al. Guidelines for the Echocardiographic Assessment of the Right Heart in Adults: A Report from the American Society of Echocardiography. JAm Soc Echocardiograph. 2010; 23(7): 685-713[DOI]
16. Kaul S, Tei C, Hopkins JM, Shah PM. Assessment of right ventricular function using two-dimensional echocardiography. Am Heart J. 1984; 107(3): 526-31[PubMed]
17. Jamal F, Bergerot C, Argaud L, Loufouat J, Ovize M. Longitudinal strain quantitates regional right ventricular contractile function. Am J Physiol Heart Circ Physiol. 2003; 285(6)-7[DOI][PubMed]
18. Kanzaki H, Nakatani S, Nakasone I, Katsuki K, Miyatake K. Regional heterogeneity of left ventricular myocardial work quantified using anatomical M-mode echocardiography. Basic Res Cardiol. 2004; 99(3): 204-11[DOI][PubMed]
19. Pierard LA, Ashman JK, Olstad B, Holm E, Berg K. Dimensional quantification of cardiac anatomy, utilizing anatomical M-mode, a new post processing technique used on high frame rate two-dimensional digitally stored cineloops. Eur Heart J. 1995; 16: 2885
20. Mele D, Pedini I, Alboni P, Levine RA. Anatomic M-mode: a new technique for quantitative assessment of left ventricular size and function. Am J Cardiol. 1998; 81(12A): 82G-5G[PubMed]