Correlation between mean pulmonary arterial pressure measurement by echocardiography and right ventricular function :Shahram Homayounfar, Nakisa Khansary, Archives of Cardiovascular Imaging

ORIGINAL ARTICLE
Year : 2018 | Volume : 6 | Issue : 1 | Page : 11--15

Correlation between mean pulmonary arterial pressure measurement by echocardiography and right ventricular function

Shahram Homayounfar, Nakisa Khansary
Department of Cardiology, Hamadan University of Medical Science, Hamadan, Iran

Correspondence Address:
Dr. Nakisa Khansary
Department of Cardiology, Hamadan University of Medical Science, Hamadan
Iran

Abstract

Background: Echocardiography is usually the first imaging modality for the evaluation of the structural and functional disorders of the heart and the great vessels. Color flow and Doppler images can provide hemodynamic and bloodstream assessment. The goal of this study was to investigate the function of the right ventricular (RV) using echocardiography in patients with an increased mean pulmonary artery pressure (PAP) (>25 mmHg). Methods: This cross-sectional study recruited patients with an elevated mean PAP (>25 mmHg) according to echocardiography. The RV function was evaluated in terms of the fractional area change (FAC), pulmonary vascular resistance (PVR), the myocardial performance index (Tei index), and the S-wave velocity. The data were analyzed using SPSS software, version 16, as well as the Chi-square test, the Pearson correlation coefficient, and the t-test. P< 0.05 was considered as statistically significant. Results: The mean FAC and the mean tricuspid annular plane systolic excursion (TAPSE) in the group with a mean PVR value of <2 WU were significantly higher than the mean FAC and the mean TAPSE in the group with a minimum mean PVR value of 2 WU (P = 0.006 andc P = 0.04, respectively). Conclusions: The RV function measured in terms of some basic echocardiographic parameters - namely the FAC, the S-wave velocity, the Tie index, and TAPSE - had a significant correlation with the mean PAP. In addition, the FAC value was more sensitive to an abnormal PVR value owing to the high frequency of the abnormal FAC values in the range of abnormal PVR values.

How to cite this article:
Homayounfar S, Khansary N. Correlation between mean pulmonary arterial pressure measurement by echocardiography and right ventricular function.Arch Cardiovasc Imaging 2018;6:11-15

How to cite this URL:
Homayounfar S, Khansary N. Correlation between mean pulmonary arterial pressure measurement by echocardiography and right ventricular function. Arch Cardiovasc Imaging [serial online] 2018 [cited 2020 Sep 30 ];6:11-15
Available from: http://www.cardiovascimaging.com/text.asp?2018/6/1/11/270150

Full Text

Introduction

Echocardiography is usually the first imaging modality for the assessment of the structural and functional disorders of the heart and the great vessels, and color flow and Doppler images can be dependably drawn on for hemodynamic and bloodstream evaluation. Echocardiography with reliable hemodynamic evaluation has dramatically reduced the need for invasive assessment.[1],[2],[3],[4]

An echocardiographic survey begins with simultaneous two-dimensional (2D) echocardiography, which furnishes high-resolution images of the structures and movements of the heart.[1],[5] Quantitative and qualitative measurements of the areas and volumes of the heart are obtained with 2D echocardiography as a framework for Doppler investigation.[6] Tissue Doppler imaging (TDI) records the movements of the tissues or the other structures of the heart that usually have less speed than does bloodstream.[7] Recent advancements in right ventricular (RV) echocardiography such as tissue Doppler, strain, and 3D imaging can provide information in addition to those provided by 2D imaging.[8],[9] RV dysfunction is associated with increased mortality in patients with congenital heart diseases, valvular diseases, coronary artery diseases, pulmonary artery hypertension, and heart failure.[10],[11],[12] Pulmonary artery hypertension is associated with secondary disturbance in RV activity,[13] which can prove life-threatening if left untreated.[14] Pulmonary artery hypertension is measured via the right heart catheterization and is considered to be an increased mean pulmonary artery pressure (PAP) at rest (mean PAP >25 mmHg).[15] At rest, a mean PAP of between 8 and 20 mmHg is deemed normal for the pulmonary artery, whereas a mean PAP of between 21 and 24 mmHg at rest is not properly determined yet.[16]

Echocardiography has long since been employed for the assessment of RV dysfunction in patients with pulmonary artery hypertension; nonetheless, cardiologists have also sought better modalities with a view to obtaining more desirable treatment outcomes. The goal of the present study was to investigate the RV function using different methods resulting from Doppler echocardiography in patients with pulmonary artery hypertension.

Methods

Inclusion and exclusion criteria

The present cross-sectional study aimed to investigate the RV function using 2D echocardiography and TDI in patients suffering from pulmonary artery hypertension with a view to finding a correlation between an increased mean PAP and the RV function. All the patients (n = 80) who were referred to Farshchian Hospital (in the Iranian city of Hamadan) with a diagnosis of pulmonary artery hypertension in 2016, together with all the patients who were diagnosed with pulmonary artery hypertension during echocardiographic examinations in Farshchian Hospital, were entered into the study, unless they met the exclusion criteria. The diagnosis of pulmonary artery hypertension was confirmed through echocardiography and the measurement of the mean PAP, with a mean PAP of >25 mmHg confirming the disease. The exclusion criteria consisted of a history of RV myocardial infarction and congenital RV abnormalities.

Echocardiographic protocol

All the study patients underwent echocardiography with TDI and 2D imaging, and the following indices were calculated.

Mean pulmonary artery pressure

Pulmonary artery systolic pressure represents the RV systolic pressure and is equivalent to PAP. The patients recruited in the current study had an increased mean PAP (>25 mmHg).

Pulmonary vascular resistance

It is measured to determine the RV workload and is an important factor in the investigation of survival among patients with pulmonary artery hypertension. The pulmonary vascular resistance (PVR) shows the extent of the dilatation of the pulmonary vascular bed with each contraction of the RV. The normal value of the PVR is <2 WU, with a minimum value of 2 WU considered abnormal.

Fractional area change

It is a determinant of the RV contractile power and a criterion for the RV ejection fraction. The fractional area change (FAC) is expressed in percentage terms, and a normal FAC value is at least 35%.

Myocardial performance index (Tei index)

It is calculated with Doppler echocardiography and is independent of electromechanical delay. The Tei index is calculated in percentage terms via the following formula:

Index of myocardial performance (Tei index) = Isovolumic contraction time + Isovolumic relaxation time/RV ejection time (IMP = IVCT + IVRT/RVET).

The time intervals required to calculate the myocardial performance index are easily obtained by Doppler echocardiography and traditional TDI. Values exceeding 44% in Doppler and 54% in TDI are deemed abnormal.

Tricuspid annular plane systolic excursion

This index is a criterion for the RV systolic function. In the echocardiographic 4-chamber view, the M-mode passes through the intersection between the tricuspid and the lateral wall of the RV and depicts a spiral view. The height of one of these waves yields tricuspid annular plane systolic excursion (TAPSE), which is 1.6 cm.

Tissue Doppler imaging

In this method, values >9.5 cm/s in the basal lateral wall of the RV are considered to be normal.

Statistical analysis

The data were entered into a checklist pertaining to each individual. The checklist contained information on age, sex, disease history, the mean PAP, the PVR value (the study population was divided into a group of PVR <2 WU and a group of PVR ≥2 WU), the FAC, the Tie index, TAPSE, RV TDI, and the underlying reason for pulmonary artery hypertension (valvular, pulmonary, rheumatologic, and congenital problems). Finally, the data of the entire study population were entered into SPSS software, version 16 IBM, Armonk, NY, USA. The data were described via descriptive statistics and inferential statistics. In addition, the Chi-square test, the Pearson correlation coefficient, and the t-test were utilized to analyze the data. The independent t-test was applied to compare the mean values between the groups, and the Pearson correlation coefficient was used to obtain the correlation values between the quantitative indices. P < 0.05 was considered as statistically significant. The executor of the study plan ensured complete data anonymization for the whole study population.

Results

The current study recruited 80 patients with pulmonary artery hypertension at Farshchian Hospital in 2016. The mean age of the patients was 57.9 years (21-92 years). The mean PAP and the mean pulmonary artery diastolic pressure were 47 and 24 mmHg, correspondingly. The mean PVR value was 2.5 WU, with the lowest value of 1.3 WU and the highest value of 5.5 WU. The other variables and central indices of the study, together with their dispersion, are presented in [Table 1].{Table 1}

[Table 2] presents the frequencies of the causes of PAP in the study population in descending order.{Table 2}

In terms of the PVR, the study population was divided into a group with a PVR value of <2 WU (25% of the patients) and a group with a minimum PVR value of 2 WU (75% of the patients). [Table 3] illustrates the central indices and their dispersion, including age, the mean PAP, the FAC, the PVR, the Tie index, and RV TDI. Based on the values mentioned in [Table 3], the differences in terms of the mean FAC (P = 0.006), the mean Tei index (P = 0.01), and the mean TAPSE (P = 0.04) were statistically significant between the 2 groups.{Table 3}

Based on the normal and abnormal values of PVR, we divided the values and the mean of FAC, RV TDI, and Tei Index into normal and abnormal group 15 in [Table 4].{Table 4}

In the entire study population, the TAPSE index value of only 3 patients was et al.[11] conducted a study on 63 patients to evaluate the RV function using Doppler echocardiography and reported that while 26 patients had primary pulmonary artery hypertension, the rest were normal in this regard. In a similar study, Kaul et al.[12] employed 2D echocardiography to assess the RV function in 30 patients. With respect to the sample size, in the current investigation, we evaluated 80 patients with pulmonary artery hypertension.

In a study by Al-Biltagi et al.,[14] a significant difference was reported concerning the mean PAP between the children in the case group and those in the control group. The mean PAP in our study was 47 mmHg. In effect, pulmonary artery systolic pressure represents the RV systolic pressure and is equivalent to PAP.

In our study, the mean PVR value was 2. 56 WU (1.3-5.5 WU). PVR values of <2 WU and equal to or >2 WU are considered normal and abnormal, respectively. The PVR is measured to evaluate the RV workload and is an important factor in the investigation of survival in patients suffering from pulmonary artery hypertension. The PVR also shows the extent of the dilatation of the pulmonary vascular bed with each contraction of the RV. We divided our study population into a group with a PVR value of <2 WU (25% of the patients) and a group with a minimum PVR value of 2 WU (75% of the patients). The mean PVR value was significantly high in a study by Gerges et al.,[15] who investigated the RV function in patients with pulmonary embolism and concluded that high PVR values impacted the RV function.

In our study, the mean FAC and the mean TAPSE were significantly higher, and the Tei index was significantly lower in the group with the normal mean PVR value than in the group with a high mean PVR value. Nevertheless, the 2 groups were not statistically significantly different vis-à-vis the mean RV TDI. Further, while the differences regarding the normal and abnormal values of the FAC, the RV TDI, and the Tei index did not constitute statistical significance among the patients with a normal mean PVR value, these differences were statistically significant in the other group. Thus, we observed a reduction in the values of the FAC and RV TDI and an increase in the Tei index in tandem with a rise in the mean PVR value in our patients with pulmonary artery hypertension. The mean FAC (%) or the RV contractile power is a criterion for the RV ejection fraction. In a study by Husain et al.,[16] there was a significant difference in the FAC values between patients with ventricular dysfunction and normal individuals, while there was no significant difference in the rest of the echocardiographic measurement of the systolic function between these 2 groups.

In our study, the mean TAPSE in the group with a PVR value of <2 WU was significantly higher than that in the group with an abnormal PVR value (≥2 WU). There was a close relationship between RV dysfunction and TAPSE in a study by Kaul et al.,[12] who also demonstrated a significant relationship between the RV ejection fraction and the regional systolic changes in the RV in the apical 4-chamber view.

Conclusions

In the present study, aiming to investigate the RV function in patients with an elevated mean PAP (>25 mmHg), there was a statistically significant correlation between the RV function and some echocardiographic parameters - namely the FAC, RV TDI, the Tei index, and TAPSE. These indices are, therefore, disturbed as a result of an increase in the degree of the pulmonary bed resistance and constitute a good criterion for the evaluation of the RV function in patients with pulmonary artery hypertension. Moreover, it appears that the FAC value was more sensitive to an abnormal PVR value due to the high frequency of the FAC abnormal values in the range of abnormal PVR values. It can be concluded that the FAC is more sensitive to elevated resistance in the pulmonary bed and is affected more noticeably than are the other aforementioned indices. The FAC can, therefore, be regarded as a good criterion in the assessment of the RV function in patients with pulmonary artery hypertension.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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