Clinical Investigation
Echocardiography in Children
Right Ventricular to Left Ventricular Diameter Ratio at End-Systole in Evaluating Outcomes in Children with Pulmonary Hypertension

https://doi.org/10.1016/j.echo.2013.10.014Get rights and content

Background

Pulmonary hypertension (PH) increases right ventricular (RV) pressure, resulting in septal shift and RV dilation. Few echocardiographic measures have been used to evaluate severity and outcomes in children with PH. The aims of this study were to compare the RV to left ventricular (LV) diameter ratio at end-systole (RV/LV ratio) in normal controls and patients with PH, to correlate the RV/LV ratio with invasive hemodynamic measures, and to evaluate its association with outcomes in children with PH.

Methods

The RV/LV ratio was compared retrospectively between 80 matched normal controls and 84 PH patients without shunts. Of the patients with PH, 49 children underwent 94 echocardiographic studies and cardiac catheterizations within 48 hours (13 patients had simultaneous measurements). The RV/LV ratio was correlated against hemodynamic measures. Kaplan-Meier curves and a Cox proportional-hazards regression model were used to assess relationships between RV/LV ratio and time until an adverse clinical event (initiation of intravenous prostacyclin therapy, atrial septostomy, death, or transplantation).

Results

RV/LV ratios were lower in controls compared with patients with PH (mean, 0.51 [95% confidence interval, 0.48–0.54] vs 1.47 [95% confidence interval, 1.25–1.70], P < .01). The RV/LV ratio correlated significantly with mean pulmonary artery pressure, systolic pulmonary artery pressure, systolic pulmonary artery pressure as a percentage of systemic pressure, and pulmonary vascular resistance index (r = 0.65 [P < .01], r = 0.6 [P < .01], r = 0.49 [P < .01], and r = 0.43 [P < .01], respectively). Twenty-two patients with PH with RV/LV ratios > 1 had adverse events within a median of 1.1 years from their earliest echocardiographic studies. Increasing RV/LV ratio was associated with an increasing hazard for a clinical event (hazard ratio, 2.49; 95% confidence interval, 1.92–3.24).

Conclusions

The RV/LV end-systolic diameter ratio can easily be obtained noninvasively in the clinical setting and can be used in the management of patients with PH. The RV/LV ratio incorporates both pathologic septal shift and RV dilation in children with PH and correlates with invasive measures of PH. An RV/LV ratio > 1 is associated with adverse clinical events.

Section snippets

Normal Controls

The University of Colorado Children's Hospital Colorado pediatric normal echocardiographic database (per an institutional review board–approved protocol) was used to retrospectively identify 80 normal controls with similar age and gender distributions as the PH cohort. All 80 normal children were evaluated for heart murmurs and had normal results on echocardiography. RV/LV ratios were obtained in normal controls and compared with RV/LV ratios in patients with PH.

Patients with PH

The University of Colorado

Results

The data consist of 80 echocardiograms in 80 normal controls and 194 echocardiographic measurements in 84 patients with PH, with a median of two observations per patient with PH (range, 1–6). Clinical diagnoses and medications in patients with PH are shown in Table 1.

Discussion

In this study, RV/LV ratio measured in the standard parasternal short-axis view was easily obtained in all subjects and feasible in 99% of all echocardiographic studies. RV/LV ratio was significantly higher in patients with PH compared with normal controls. RV/LV ratios correlated well with invasive hemodynamic measures, and increased RV/LV ratio was associated with adverse clinical events, making this new index a potentially clinical relevant parameter in patients with PH.

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Conclusions

The RV/LV end-systolic diameter ratio incorporates both pathologic septal shift and RV dilation in PH and correlates with invasive hemodynamic measures of PH. The RV/LV ratio can easily be obtained in the clinical setting and appears to be a strong predictor of outcome. The RV/LV ratio may be a valuable additional echocardiographic measure in the quest to find a surrogate technology for cardiac catheterization in children with PH.

Acknowledgments

We would like to acknowledge the contributions of Courtney Cassidy and Allison Sterk in data collection.

References (34)

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    Citation Excerpt :

    One effect of RV pressure and/or volume overload is the ventricular septal shift and D-shaped ventricular septal contour, which can be quantified by echocardiogram with the eccentricity index, a ratio of lateral to antero-posterior LV dimensions. The ratio of RV to LV dimensions in short-axis view >1 at end-systole has been associated with adverse clinical outcomes in children with pulmonary hypertension [123]. Comparing echocardiographic LV deformation with cardiac magnetic resonace imaging and exercise data, Cheung et al. showed that LV deformation is impaired in patients with tetralogy of Fallot when compared with controls and that circumferential deformation of the LV is inversely correlated with RV end-systolic volume and positively correlated with exercise capacity [124].

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This study was supported by the Frederick and Margaret L Weyerhaeuser Foundation, the Jayden DeLuca Foundation, the Leah Bult Foundation, Colorado Clinical Translational Science Institute (UL1 TR000154), National Center for Research Resources, and National Institutes of Health, P50 HL084923, and RO1 HL114753.

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