Overestimation by echocardiography of the peak systolic pressure gradient between the right ventricle and right atrium due to tricuspid regurgitation and the usefulness of the early diastolic transpulmonary valve pressure gradient for estimating pulmonary artery pressure

Incremental Prognostic Value of Right Ventricular-Pulmonary Artery Coupling to a Clinical Risk Score in Tricuspid Regurgitation: The TRIO-RV Score

OBJECTIVES

There are limited data evaluating the echocardiographic parameters of risk in tricuspid regurgitation (TR) patients. We sought to evaluate the incremental prognostic value of quantitative right ventricle (RV) function and RV-pulmonary artery (RV-PA) coupling to an established clinical risk score in TR patients.

METHODS

We retrospectively identified patients with moderate or greater TR from January 1, 2019, to June 30, 2019. Univariable and multivariable Cox proportional hazards regressions were used to test the association of right ventricular free wall strain (RVFWS), RVFWS indexed to right ventricular systolic pressure (RVSP), and the Tricuspid Regurgitation Impact on Outcomes (TRIO) risk score with mortality. A novel TRIO-RV risk score was developed by incorporating RVFWS/RVSP into the clinical TRIO risk score.

RESULTS

Among 417 patients, age 73 ± 11.5 years, 47% female, the TRIO score was 3.5 ± 2. The TRIO score was low risk in 213 (51%), intermediate risk in 162 (39%), and high risk in 42 (10%). During a median follow-up of 3.96 years (interquartile range, 1.66-4.34 years), death occurred in 157 patients (38%). The baseline TRIO risk category was associated with mortality (P < .001). After adjustment by TRIO risk score, both RVFWS <18.6% (adjusted hazard ratio, 3.08; 95% CI, 2.01-4.72; P < .001) and RVFWS/RVSP <0.43 %/mm Hg (adjusted hazard ratio, 2.76; 95% CI, 1.75-4.35, P < .001) remained significantly correlated with mortality. With the addition of RVFWS/RVSP, 151 (40%) patients with low- and intermediate-risk TRIO scores were reclassified to a higher-risk TRIO-RV score. The chi-square value increased in sequential models predictive of mortality for the TRIO score alone, the TRIO score plus RVFWS <18.6%, and the TRIO score plus RVFWS/RVSP <0.43 %/mm Hg (model chi-square 38.3, 72.2, and 82.3, respectively).

CONCLUSIONS

Quantitative parameters of RV function are associated with mortality in TR patients even after correction for an existing clinical risk score. Incorporating RVFWS/RVSP into the TRIO clinical risk score, the TRIO-RV score, reclassifies a substantial number of low- and intermediate-risk patients into higher-risk categories and improves risk stratification.

The accuracy and influencing factors of Doppler echocardiography in estimating pulmonary artery systolic pressure: comparison with right heart catheterization: a retrospective cross-sectional study

Background

Noninvasive assessment of pulmonary artery systolic pressure by Doppler echocardiography (sPAP_ECHO) has been widely adopted to screen for pulmonary hypertension (PH), but there is still a high proportion of overestimation or underestimation of sPAP_ECHO. We therefore aimed to explore the accuracy and influencing factors of sPAP_ECHO with right heart catheterization (RHC) as a reference.

Methods

A total of 218 highly suspected PH patients who underwent RHC and echocardiography within 7 days were included. The correlation and consistency between tricuspid regurgitation (TR)-related methods and RHC results were tested by Pearson and Bland–Altman methods. TR-related methods included peak velocity of TR (TR Vmax), TR pressure gradient (TR-PG), TR mean pressure gradient (TR-mPG), estimated mean pulmonary artery pressure (mPAP_ECHO), and sPAP_ECHO. With mPAP ≥ 25 mm Hg measured by RHC as the standard diagnostic criterion of PH, the ROC curve was used to compare the diagnostic efficacy of sPAP_ECHO with other TR-derived parameters. The ratio (sPAP_ECHO–sPAP_RHC)/sPAP_RHC was calculated and divided into three groups as follows: patients with an estimation error between − 10% and + 10% were defined as the accurate group; patients with an estimated difference greater than + 10% were classified as the overestimated group; and patients with an estimation error greater than − 10% were classified as the underestimated group. The influencing factors of sPAP_ECHO were analyzed by ordinal regression analysis.

Results

sPAP_ECHO had the highest correlation coefficient (r = 0.781, P < 0.001), best diagnostic efficiency (AUC = 0.98), and lowest bias (mean bias = 0.07 mm Hg; 95% limits of agreement, − 32.08 to + 32.22 mm Hg) compared with other TR-related methods. Ordinal regression analysis showed that TR signal quality, sPAP_RHC level, and pulmonary artery wedge pressure (PAWP) affected the accuracy of sPAP_ECHO (P < 0.05). Relative to the good signal quality, the OR values of medium and poor signal quality were 0.26 (95% CI: 0.14, 0.48) and 0.23 (95% CI: 0.07, 0.73), respectively. Compared with high sPAP_RHC level, the OR values of low and medium sPAP_RHC levels were 21.56 (95% CI: 9.57, 48.55) and 5.13 (95% CI: 2.55, 10.32), respectively. The OR value of PAWP was 0.94 (95% CI: 0.89, 0.99). TR severity and right ventricular systolic function had no significant effect on the accuracy of sPAP_ECHO.

Conclusions

In this study, we found that all TR-related methods, including sPAP_ECHO, had comparable and good efficiency in PH screening. To make the assessment of sPAP_ECHO more accurate, attention should be paid to TR signal quality, sPAP_RHC level, and PAWP.

Ventricular systolic dysfunction with and without altered myocardial contractility: Clinical value of echocardiography for diagnosis and therapeutic decision-making

The inability of one of the two or both ventricles to contract normally and expel sufficient blood to meet the functional demands of the body results from a complex interplay between intrinsic abnormalities and extracardiac factors that limit ventricular pump function and is a major cause for heart failure (HF). Even if impaired myocardial contractile function was the primary cause for ventricular dysfunction, with the progression of systolic dysfunction, additionally developed diastolic dysfunction can also contribute to the severity of HF. Although at the first sight, the diagnosis of systolic HF appears quite easy because it is usually defined by reduction of the ejection fraction (EF), in reality this issue is far more complex because ventricular pumping performance depends not only on myocardial contractility, but also largely on loading conditions (preload and afterload), being also influenced by valvular function, ventricular interdependence, pericardial constraint, synchrony of ventricular contrac-tion and heart rhythm. Conventional echocardiography (ECHO) combined with new imaging techniques such as tissue Doppler and tissue tracking can detect early subclinical alteration of ventricular systolic function. However, no single ECHO parameter reveals alone the whole picture of systolic dysfunction. Multiparametric ECHO evaluation and the use of integrative approaches using ECHO-parameter combinations which include also the ventricular loading conditions appeared particularly useful especially for differentiation between primary (myocardial damage-induced) and secondary (hemodynamic overload-induced) systolic dysfunction. This review summarizes the available evidence on the usefulness and limitations of comprehensive evaluation of LV and RV systolic function by using all the currently available ECHO techniques.

Right ventricular basal inflow and outflow tract diameters overestimate right ventricular size in subjects with sigmoid-shaped interventricular septum: a study using three-dimensional echocardiography

Sigmoid-shaped ventricular septum (SS), a frequently encountered minor abnormality in echocardiographic examinations of the elderly, may have some influence on RV shape. We aimed to determine the influence of SS on the accuracy of the 6 RV linear diameter measurements in the light of three-dimensional echocardiographic (3DE) RV volume. The aorto-septal angle (ASA) was measured in the parasternal long-axis view using two-dimensional echocardiography (2DE) as an index of SS in 70 patients without major cardiac abnormalities who were subdivided into 35 with SS (ASA ≤ 120°) and 35 without SS (NSS). We measured RV end-diastolic volume (RVEDV) using 3DE; in addition, using 2DE, we measured basal RV diameter, mid-cavity diameter, longitudinal diameter and end-diastolic area in the apical four-chamber view; proximal RV outflow tract (RVOT) diameter in the parasternal long-axis view; and proximal and distal RVOT diameters in the parasternal short-axis view. RVEDV did not differ between the SS and NSS groups. The SS group had greater basal RV diameter and proximal and distal RVOT diameters than the NSS group. RV mid-cavity diameter, longitudinal diameter, and end-diastolic area did not differ between the groups. Among the 2DE parameters of RV size, RV end-diastolic area was most strongly correlated with RVEDV (r = 0.67), followed by RV mid-cavity diameter (r = 0.58). When SS is present, the echocardiographic basal RV diameter and RVOT diameters overestimate RV size, and the measurement of RV end-diastolic area and mid-cavity diameter more correctly reflect 3D RV volume.

Non-Invasive Assessment of Intravascular Pressure Gradients: A Review of Current and Proposed Novel Methods

Invasive catheterization is associated with a low risk of serious complications. However, although it is the gold standard for measuring pressure gradients, it induces changes to blood flow and requires significant resources. Therefore, non-invasive alternatives are urgently needed. Pressure gradients are routinely estimated non-invasively in clinical settings using ultrasound and calculated with the simplified Bernoulli equation, a method with several limitations. A PubMed literature search on validation of non-invasive techniques was conducted, and studies were included if non-invasively estimated pressure gradients were compared with invasively measured pressure gradients in vivo. Pressure gradients were mainly estimated from velocities obtained with Doppler ultrasound or magnetic resonance imaging. Most studies used the simplified Bernoulli equation, but more recent studies have employed the expanded Bernoulli and Navier⁻Stokes equations. Overall, the studies reported good correlation between non-invasive estimation of pressure gradients and catheterization. Despite having strong correlations, several studies reported the non-invasive techniques to either overestimate or underestimate the invasive measurements, thus questioning the accuracy of the non-invasive methods. In conclusion, more advanced imaging techniques may be needed to overcome the shortcomings of current methods.

Echocardiographic surrogates of right atrial pressure in pulmonary hypertension

Right atrial pressure (RAP), a representative parameter of right heart failure, is very important for prognostic evaluation and risk assessment in pulmonary hypertension. However, its measurement requires invasive cardiac catheterization. In this study, we determined the most accurate echocardiographic surrogate of catheterization-based RAP. In 23 patients with pulmonary hypertension, a total of 66 cardiac catheterization procedures were performed along with 2-dimensional echocardiography. We evaluated tricuspid E/A, E', A' and E/E', and estimated RAP by the respirophasic variation of the inferior vena cava diameter (eRAP-IVCd) as possible surrogates of catheterization-based RAP. In simple linear regression analysis, E/A (R = 0.452, P = 0.0001) and eRAP-IVCd (R = 0.505, P < 0.0001) were positively correlated with catheterization-based RAP, whereas A' (R = - 0.512, P < 0.0001) was negatively correlated with RAP. In multiple regression analysis, A' was the most significant independent predictor of catheterization-based RAP (R = - 0.375, P = 0.0007). In 16 patients who had multiple measurements, there were a total of 43 measurements before and after medication changes. The absolute change in catheterization-based RAP was negatively correlated with the percent change in A'. Receiver operating characteristic curve analysis indicated that the optimal cut-off value of A' to predict a catheterization-based RAP > 10 mmHg was 11.3 cm/s (area under the curve = 0.782, sensitivity = 0.70, specificity = 0.78). In 20 measurements of 20 patients with left heart failure, catheterization-based RAP was not correlated with any of 5 echocardiographic parameters. However, it was closely correlated with catheterization-based pulmonary capillary wedge pressure. The echocardiographic parameter, A', was the best surrogate of catheterization-based RAP in patients with pulmonary hypertension.

A subclinical high tricuspid regurgitation pressure gradient independent of the mean pulmonary artery pressure is a risk factor for the survival after living donor liver transplantation

BACKGROUND

Portopulmonary hypertension (POPH) is characterized by pulmonary vasoconstriction, while hepatopulmonary syndrome (HPS) is characterized by vasodilation. Definite POPH is a risk factor for the survival after orthotopic liver transplantation (OLT), as the congestive pressure affects the grafted liver, while subclinical pulmonary hypertension (PH) has been acknowledged as a non-risk factor for deceased donor OLT. Given that PH measurement requires cardiac catheterization, the tricuspid regurgitation pressure gradient (TRPG) measured by echocardiography is used to screen for PH and congestive pressure to the liver. We investigated the impact of a subclinical high TRPG on the survival of small grafted living donor liver transplantation (LDLT).

METHODS

We retrospectively analyzed 84 LDLT candidates. Patients exhibiting a TRPG ≥25 mmHg on echocardiography were categorized as potentially having liver congestion (subclinical high TRPG; n = 34). The mean pulmonary artery pressure (mPAP) measured after general anesthesia with FIO₂0.6 (mPAP-FIO₂0.6) was also assessed. Patients exhibiting pO₂ < 80 mmHg and an alveolar-arterial oxygen gradient (AaDO₂) ≥ 15 mmHg were categorized as potentially having HPS (subclinical HPS; n = 29). The clinical course after LDLT was investigated according to subclinical high TRPG.

RESULTS

A subclinical high TRPG (p = 0.012) and older donor age (p = 0.008) were correlated with a poor 40-month survival. Although a higher mPAP-FIO₂0.6 was expected to correlate with a worse survival, a high mPAP-FIO₂0.6 with a low TRPG was associated with high frequency complicating subclinical HPS and a good survival, suggesting a reduction in the PH pressure via pulmonary shunt.

CONCLUSION

In cirrhosis patients, mPAP-FIO₂0.6 may not accurately reflect the congestive pressure to the liver, as the pressure might escape via pulmonary shunt. A subclinical high TRPG is an important marker for predicting a worse survival after LDLT, possibly reflecting congestive pressure to the grafted small liver.

Usefulness of scoring right ventricular function for assessment of prognostic factors in patients with chronic thromboembolic pulmonary hypertension

Right ventricular (RV) function is associated with prognosis in chronic thromboembolic pulmonary hypertension (CTEPH). This study aimed to establish an RV dysfunction score using RV echocardiographic parameters to clarify the clinical characteristics in patients with CTEPH and to compare RV dysfunction score with parameters such as World Health Organization (WHO) functional class, hemodynamics, exercise capacity, and plasma BNP level. We enrolled 35 inpatients with CTEPH (mean age, 62 ± 15 years, 15 males). We constructed ‘an RV dysfunction score’ calculated as the summation of each point awarded for the presence of four parameters: tricuspid annular plane systolic excursion (TAPSE) < 16 mm, 1 point; tissue Doppler-derived tricuspid lateral annular systolic velocity (S′) < 10 cm/s, 1 point; right ventricular fractional area change (RVFAC) < 35%, 1 point; and right ventricular myocardial performance index (RV-MPI) > 0.4, 1 point. TAPSE, S′, RVFAC, and RV-MPI was 18.7 ± 4.8 mm, 11.9 ± 3.1 cm/s, 33.5 ± 13.9%, and 0.39 ± 0.2, respectively. The RV dysfunction score was associated with symptom [WHO functional class (p = 0.026)], hemodynamics [mean PAP (p = 0.01), cardiac index (p = 0.009), pulmonary vascular resistance (p = 0.001), and SvO₂ (p = 0.039)], exercise capacity [6-min walk distance (p = 0.046), peakVO₂ (p = 0.016), and VE/VCO₂ slope (p = 0.031)], and plasma BNP level (p = 0.005). This RV dysfunction score using the four RV echocardiographic parameters could be a simple and useful scoring system to evaluate prognostic factors in patients with CTEPH.

Left ventricular end-diastolic dimension and septal e' are predictors of cardiac index at rest, while tricuspid annular plane systolic excursion is a predictor of peak oxygen uptake in patients with pulmonary hypertension

Little is known regarding a correlation of hemodynamics at rest or exercise capacity with echocardiographic parameters in patients with pulmonary hypertension (PH). To clarify these potential correlations, we performed transthoracic echocardiography, right heart catheterization, and cardiopulmonary exercise testing in 53 patients with pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH). Left ventricular end-diastolic dimension (LVDd), early diastolic velocity of the septal mitral annulus (septal e'), tricuspid regurgitation peak gradient (TRPG), and tricuspid annular plane systolic excursion (TAPSE) were significantly correlated with cardiac index (LVDd; r = 0.477, P < 0.001, septal e'; r = 0.463, P = 0.001, TRPG; r = - 0.455, P = 0.001 and TAPSE; r = 0.406, P = 0.003, respectively). Multiple regression analysis revealed that LVDd and septal e' were significantly associated with cardiac index (CI) and stroke volume index at rest. Among the exercise capacity markers evaluated, TAPSE, TRPG, and LVDd were significantly correlated with peak oxygen uptake (TAPSE; r = 0.534, P < 0.001, TRPG; r = - 0.466, P = 0.001 and LVDd; r = 0.411, P = 0.002, respectively). Multiple regression analysis showed that TAPSE was significantly associated with peak oxygen uptake (VO₂). In PAH and CTEPH patients, LVDd and septal e' were significantly associated with CI at rest, whereas TAPSE was significantly associated with peak VO₂. Echocardiographic parameters may predict the prognostic factors of PAH and CTEPH patients.

Comparison of echocardiographic parameters to assess right ventricular function in pulmonary hypertension

Although measurement of right ventricular ejection fraction (RVEF) may be relevant for evaluation of therapeutic efficacy and/or prognosis in patients with pulmonary hypertension, RVEF obtained by echocardiography has limited accuracy. In contrast, radionuclide and/or magnetic resonance imaging can measure RVEF more reliably. In this study, we investigated the relationship between RVEF measured by radionuclide angiography and the echocardiographic parameters that are recommended by the American Society of Echocardiography as representative of right heart function. There were 23 study participants with pulmonary hypertension who underwent radionuclide angiography and 2-dimensional and Doppler echocardiography (n = 30 measurements). RVEF measured by radionuclide angiography correlated with right ventricular Tei index (RV Tei index) measured by Doppler echocardiography (r = -0.601, P < 0.0005). Receiver operating characteristic curve analysis showed that an RV Tei index cut-off value of 0.371 was the best of predictor of RVEF ≤35% (area under the curve = 0.768, sensitivity = 0.857, selectivity = 0.667). Multiple regression analysis showed that RVEF was correlated with the RV Tei index, and this association was independent of other echocardiographic right ventricular function parameters (r = -0.644, P < 0.005). The RV Tei index measured by Doppler echocardiography may be an acceptable surrogate marker of RVEF in patients with pulmonary hypertension.