|INTERESTING CASE REPORT
|Ahead of print publication
Assessment of Right Ventricle Function in Children with Pulmonary Arterial Hypertension - Moving Beyond Longitudinal Motion
Mani Ram Krishna
Department of Pediatric Cardiology, R.K. Hospital for Women and Children, Thanjavur, Tamil Nadu, India
|Date of Submission||21-Dec-2020|
|Date of Acceptance||06-Feb-2021|
|Date of Web Publication||05-Apr-2021|
Mani Ram Krishna,
R.K. Hospital for Women and Children, 7, V.O.C. Nagar, Thanjavur - 613 007, Tamil Nadu
Source of Support: None, Conflict of Interest: None
Right ventricular (RV) systolic function is an important determinant of clinical outcomes in patients with pulmonary arterial hypertension (PAH). However, RV function assessment is less well defined than left ventricle function and requires the use of multiple echocardiographic indices. We report a child with severe PAH and RV dysfunction in whom traditional measures of RV systolic function were deceptive.
Keywords: Auto strain right ventricle, pediatric pulmonary arterial hypertension, speckle tracking echocardiography
|How to cite this URL:|
Krishna MR. Assessment of Right Ventricle Function in Children with Pulmonary Arterial Hypertension - Moving Beyond Longitudinal Motion. J Indian Acad Echocardiogr Cardiovasc Imaging [Epub ahead of print] [cited 2021 Jul 23]. Available from: https://www.jiaecho.org/preprintarticle.asp?id=313091
| Introduction|| |
Right ventricle (RV) for long remained the forgotten ventricle in cardiac imaging, with most developments focused on improving assessment of the left ventricle by noninvasive imaging. This trend has reversed in recent years with increasing focus on comprehensive imaging of the RV and development of robust parameters to assess the RV health in various disease states. RV systolic function is recognized as an important prognostic factor in children and adults with pulmonary arterial hypertension (PAH). However, there is no single modality which has been shown to accurately assess RV function, and a comprehensive assessment should be performed using different echocardiographic modalities. A case report is presented where traditional methods of RV function assessment were deceptive in gauging the severity of ventricular dysfunction.
| Clinical Details|| |
A 9-year-old female child with PAH was referred to us for complete evaluation. She had been diagnosed with idiopathic PAH at 4 years of age and had been on dual pulmonary vasodilator therapy. She reported functional class II symptoms. There were no episodes of palpitation, giddiness, or syncope. She did not have peripheral edema, and her liver was only palpable 3 cm below her right costal margin. On cardiac examination, she had parasternal heave and a palpable pulmonary component of second heart sound. Her first heart sound was normal, and second heart sound was split with a loud pulmonic component. There was no systolic murmur, but a harsh early diastolic murmur was heard at the base. Her resting heart rate was 100/min and her oxygen saturation (SpO2) was 88% on room air. On a 6-min walk test, she was able to walk 300 m with a SpO2 drop to 78%. Her fatigue level measured by the Borg fatigue scale was 5.
Her heart was structurally normal except for a moderate-sized atrial communication with predominantly right-to-left shunt. There was no pericardial effusion. The inferior caval vein was dilated, measuring 17 mm in expiration (z-score: +2.08) but collapsed to 4 mm with inspiration. The right atrium (RA) was dilated with a volume of 40 ml and an area of 15.2 mm2 (z-score: +3.2) in end systole. On subjective assessment, the RV was dilated with severe systolic dysfunction [Video 1] and [Video 2]. The estimated RV systolic pressure by tricuspid valve Doppler was 56 mmHg above the RA pressure based on the modified Bernoulli principle. The estimated mean pulmonary artery pressure based on the peak pulmonary regurgitation velocity was 47 mmHg. A comprehensive assessment of RV function was performed. The tricuspid valve annular plane systolic excursion (TAPSE) was 15.6 mm (z-score: −3.86) [Figure 1]a. The RV S velocity by tissue Doppler pulse wave imaging of the lateral tricuspid annulus was 13.5 cm/s [Figure 1]b. These values appeared disproportionately normal for the severity of dysfunction based on subjective assessment. The RV fractional area change from a RV-focused apical four-chamber (A4C) view was only 22% [Figure 1]c and [Figure 1]d. The ventricular systolic: diastolic ratio calculated based on the tricuspid regurgitation Doppler was 4:1 [Figure 1]e. The RV fractional shortening by M mode in the parasternal short axis was −0.5%. The RV free wall strain and total RV strain were measured by speckle tracking echocardiography (STE) from an RV-focused A4C view, offline using a dedicated software. Both values were very low at −4.5% and −4%, respectively [Figure 2].
|Figure 1: (a) M mode echocardiography image from a right ventricle-focused apical four-chamber view demonstrating the tricuspid annular plane systolic excursion of the child. (b) Tissue Doppler imaging of the lateral tricuspid valve annulus measuring the right ventricle S velocity in this child. (c and d) Two-dimensional echocardiographic images of a right ventricle-focused apical four-chamber view in diastole and systole demonstrating the change in area of the right ventricle. (e) Continuous wave Doppler interrogation of the tricuspid valve. The tricuspid valve regurgitation represents systole. The duration of systole and diastole are measured to be 473 and 127 ms with a systole: diastole ratio of 4:1|
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|Figure 2: Right ventricular speckle tracking echocardiography from a right ventricle-focused apical four-chamber view demonstrating very low free wall strain|
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Video 1: Echocardiogram loop from an apical 4 chamber view with right ventricular systolic dysfunction apparent on subjective assessment.
[Additional file 1]
Video 2: Echocardiogram loop from a para-sternal short-axis view showing right ventricular systolic dysfunction on subjective assessment.
[Additional file 2]
| Discussion|| |
RV failure is the final pathway to clinical deterioration and death in patients with PAH. It is hence important to assess RV function objectively during each follow-up visit. Noninvasive assessment of RV function can be obtained using echocardiography and cardiac magnetic resonance (CMR) imaging. The estimation of RV ejection fraction remains the gold standard for assessment of RV function and can be obtained reliably by CMR. However, CMR is an expensive and time-consuming investigation and is not widely available in our country. Hence, echocardiography remains the most widely used noninvasive modality in the assessment of RV function.
The importance of longitudinal contraction in RV ejection has been recognized, and TAPSE has been recommended as a measure of RV function by professional bodies for many years. TAPSE has been shown to correlate with poor outcomes in PAH. TAPSE has remained an attractive clinical tool for assessing RV function among clinicians because of the ease in obtaining the value and inter- and intra-observer reproducibility. However, TAPSE measures the longitudinal motion of only one segment, while RV is a complex crescentic shaped structure with an inlet, body, and outlet. The RV enlargement and apical rotation which occurs in patients with long-standing pulmonary hypertension often result in a rocking movement of the RV, which pulls the base of the heart downward passively by myocardial tethering. This results in a falsely elevated TAPSE. The same principle could also potentially result in an increased RV S velocity on tissue Doppler imaging. In our case, the rocking motion was evident on the RV-focused four-chamber view and could potentially have resulted in an increased TAPSE and RV S velocity.
The recognition of this limitation has resulted in renewed interest in additional parameters for RV function assessment. RV free wall strain by STE has emerged as a credible alternative. It is not angle dependent and is less susceptible to passive motion due to myocardial tethering. Early studies have shown decreased longitudinal deformation in children with idiopathic PAH and have postulated that it may predict adverse outcomes. Additional modalities utilized to assess RV function include the RV systolic: diastolic ratio (a value greater than 1.4: 1 has been shown to be associated with a high risk for adverse outcomes), RV transverse shortening, and RV fractional area change. Each of these parameters was abnormal in our child and suggested severe RV systolic dysfunction.
| Conclusion|| |
Echocardiogram remains the primary investigation modality in children with PAH. A comprehensive assessment of RV systolic function utilizing all available echocardiographic parameters is superior to conventional measurements which focus on the assessment of longitudinal motion.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]