Correlation between Echocardiography and Cardiac Catheterization for the Assessment of Pulmonary Hypertension in Pediatric Patients

Introduction

Cardiac catheterization is widely considered the “gold standard” for the diagnosis of pulmonary hypertension. However, its routine use is limited due to its invasive nature. Therefore, the aim of this study was to evaluate the correlation between pulmonary artery pressures obtained by various parameters of transthoracic echocardiography and cardiac catheterization.

Methods

This study includes 50 consecutive patients with intracardiac shunt lesions diagnosed with severe pulmonary hypertension on echocardiography and admitted for cardiac catheterization at the National Institute of Cardiovascular Diseases (NICVD) in Karachi, Pakistan. Cardiac catheterization and transthoracic echocardiography were performed in all patients simultaneously and systolic (sPAP) and mean pulmonary artery pressure (mPAP) were assessed with both modalities. Correlations and agreement, in terms of Bland-Altman plot, were computed between both modalities for sPAP and mPAP.

Results

Out of 50 patients, 46% (23) were male and mean age was 7.49 ± 4.45 years. On cardiac catheterization, sPAP was 93.92 ± 17.91 mmHg and mPAP was 67.0 ± 14.28 mmHg. Correlation between cardiac catheterization and echocardiography for the assessment of sPAP was 0.917 (p<0.001), and mPAP was 0.832 (p<0.001) for mean gradient of tricuspid regurgitation (PGTRmean), 0.749 (p<0.001) for peak gradient of pulmonary regurgitation (PGPRpeak), 0.691 (p<0.001) for Acceleration time across right ventricular outflow tract (RVOT), and 0.752 (p<0.001) for end gradient of pulmonary regurgitation (PGPRend). Bland-Altman plot showed moderate agreement between two modalities.

Conclusion

A positive but modest correlation was observed between hemodynamic parameters of transthoracic echocardiography and cardiac catheterization for assessment of pulmonary artery pressures. Transthoracic echocardiography can reliably be used as an initial non-invasive modality for the assessment of pulmonary artery hypertension and can obviate the need of right heart catheterization in some patient especially with mild pulmonary hypertension.

Noninvasive assessment of elevated pulmonary vascular resistance in children with pulmonary hypertension secondary to congenital heart disease: A comparative study between five different Doppler indices

BACKGROUND

Pulmonary vascular resistance (PVR) is an important hemodynamic parameter in patients with congenital heart disease (CHD). Noninvasive estimation of PVR represents an attractive alternative to invasive measurements.

METHODS

The study included 175 patients with pulmonary hypertension (PH) secondary to CHD. All patients underwent full echocardiographic study and invasive hemodynamic measurements. The study population was then subdivided into four subgroups. Each of the following Doppler indices was measured in one of these four subgroups: peak tricuspid regurgitant velocity (TRV), the ratio of the TRV to the velocity time integral of the right ventricular outflow tract (TRV/TVIRVOT), peak velocity of tricuspid annular systolic motion (TSm), heart rate corrected acceleration time and infliction time of the proximal left pulmonary artery (ATc, InTc). The data obtained was correlated with invasive PVR measurement. An ROC curve analysis was done to generate cutoff points with the highest balanced sensitivity and specificity to predict PVR > 6WU/m(2). The receiver operating characteristics (ROC) curves were compared with each other to determine the most reliable cutoff point in predicting elevated PVR > 6WU/m(2).

RESULTS

There was a significant correlation between both the TRV and TSm and invasive measurement of PVR (r = -0.511, 0.387 and P value = 0.0002, 0.006 respectively). The TSm and TRV cutoff values were the most reliable to predict elevated PVR > 6 WU/m(2). A TSm cutoff value of ⩽16.16 cm/s provided the best balanced sensitivity (85.7%) and specificity (66.7%) to determine PVRCATH > 6 WU/m(2). A cutoff value less than 7.62 cm/s had 100% specificity to predict PVRCATH > 6 WU/m(2). A TRV cutoff value of >3.96 m/s provided the best balanced sensitivity (66.7%) and specificity (100%) to determine PVRCATH > 6 WU/m(2). Both TRV and TSm had the highest area under the ROC curve among the 5 DOPPLER indices studied.

CONCLUSION

Prediction of elevated PVR in children with PH secondary to CHD could be achieved noninvasively using a number of Doppler indices. Among the five Doppler indices examined in the current study, the peak TRV and the TSm of the lateral tricuspid annulus had the highest balanced sensitivity and specificity to predict PVRI > 6 WU/m(2).

Accuracy of Doppler-derived estimation of pulmonary vascular resistance in congenital heart disease: an index of operability

Pulmonary vascular resistance (PVR) is a critical and essential parameter during the assessment and selection of modality of treatment in patients with congenital heart disease (CHD) accompanied by pulmonary arterial hypertension (PAH). Cardiac catheterization is the "gold standard" but is an invasive method for PVR measurement. A noninvasive and reliable method for estimation of PVR in children has been a major challenge and most desirable during past decades, especially for those who need repeated measurements. In a prospective study and among consecutive patients who were referred for cardiac catheterizations, PVR was calculated as the ratio of the transpulmonary pressure gradient (∆P) to the amount of the pulmonary flow (QP) accordingly for 20 patients with CHD and high PAH. Subsequently and noninvasively, PVR was assessed for these patients by a Doppler echocardiography-derived index defined as the ratio of the tricuspid regurgitation velocity (TRV(m/s)) to the velocity time integral (VTI(cm)) of the right-ventricular outflow tract (RVOT). There was a good correlation between PVR measured at catheterization (PVR(cath)) and TRV/VTI(m) ratio; the mean of three measurements of VTI (VTI(m)) with R (2) = 0.53 (p = 0.008). In addition, a TRV/VTI(m) value of 0.2 provided a sensitivity of 71.4% and a specificity of 100% for PVR >6 Woods units (WU) as well as sensitivity of 90% and specificity of 90% for a PVR equal to 8 WU. PVR value between 6 and 8 WU by catheterization has been considered as a cut-off point for intervention in children with left-to-right shunts and PAH. In conclusion, Doppler-derived TRV/VTI(m) ratio is a reliable index that may be helpful as a supplementary diagnostic tool for the selection of modality of treatment and follow-up of patients with PAH and increased PVR.