Strain and strain rate echocardiography for evaluation of right ventricular dysfunction in patients with idiopathic pulmonary arterial hypertension

Role of functional echocardiographic parameters in the diagnosis of bronchopulmonary dysplasia-associated pulmonary hypertension

Echocardiogram (echo) is a commonly used noninvasive modality for the diagnosis of bronchopulmonary dysplasia associated pulmonary hypertension (BPD-PH). Though not considered the gold standard for the diagnosis of BPD-PH, it is an extremely valuable tool in the neonatal and pediatric population, especially when cardiac catheterization is not feasible. In addition to the traditional echo parameters that are used to assess the presence of BPD-PH, much attention has been recently placed on newer bedside echo measures, the so-called functional echo parameters, to aid and assist in the diagnosis. This review article provides a brief introduction to BPD-PH, describes the pitfalls of traditional echo parameters and details the newer echo modalities currently available for the diagnosis of neonatal PH.

Pulmonary hypertension in the developing world: Local registries, challenges, and ways to move forward

Pulmonary hypertension (PH) is a disease that can only be appropriately managed in the ‘rich’ developed countries, as both diagnostic and therapeutic interventions are extremely expensive and expectations for these to be adopted by the developing, economically-challenged countries are neither practical nor realistic. Furthermore, most of the enormous advances in understanding the pathobiology of PH and the subsequent evidence-based diagnostic and complex treatment algorithms came from the developed world.

Two-dimensional speckle tracking echocardiography assessed right ventricular function and exercise capacity in pre-capillary pulmonary hypertension

Resting two-dimensional speckle tracking echocardiography (2D-STE) identified right ventricular (RV) systolic function were reported to predict exercise capacity in pulmonary hypertension (PH) patients, but little attention had been payed to 2D-STE detected RV diastolic function. Therefore, we aim to elucidate and compare the relations between 2D-STE identified RV diastolic/systolic functions and peak oxygen consumption (PVO₂) determined by cardiopulmonary exercise testing (CPET) in pre-capillary PH. 2D-STE was performed in 66 pre-capillary PH patients and 28 healthy controls. Linear correlation and multivariate regression analyses were performed to evaluate and compare the relations between RV 2D-STE parameters and PVO₂. Receiver operating characteristic curves were used to compare the predictive value of 2D-STE parameters in predicting the cut-off-PVO₂ < 11 ml/min/kg. There were significant differences of all the 2D-STE parameters between PH patients and healthy controls. In patients, RV-peak global longitudinal strain (GLS, r_s = - 0.498, P < 0.001), RV- peak systolic strain rate (GSRs, r_s = - 0.537, P < 0.001) and RV- peak early diastolic strain rate (GSRe, r_s = 0.527, P < 0.001) significantly correlated with PVO₂, but no significant correlation was observed between RV- peak late diastolic strain rate (GSRa, r_s = 0.208, P = 0.093) and PVO₂. The first multivariate regression analysis of clinical data without echocardiographic parameters identified WHO functional class, NT-proBNP and BMI as independent predictors of PVO₂ (Model-1, adjusted r² = 0.421, P < 0.001); Then we added conventional echocardiographic parameters and 2D-STE parameters to the clinical data, identified S,(Model-2,adjusted r² = 0.502, P < 0.001), RV-GLS (Model-3, adjusted r² = 0.491, P < 0.001), RV-GSRe (Model-4, adjusted r² = 0.500, P < 0.001) and RV-GSRs (Model-5, adjusted r² = 0.519, P < 0.001) as independent predictors of PVO₂, respectively. The predictive power was increased, and Model-5 including RV-GSRs showed the highest predictive capability. ROC curves found RV-GSRs expressed the strongest predictive value (AUC = 0.88, P < 0.001), and RV-GSRs > - 0.65/s had a 88.2% sensibility and 82.2% specificity to predict PVO₂ < 11 ml/min/kg. 2D-STE assessed RV function improves the prediction of exercise capacity represented by PVO₂ in pre-capillary PH.

Diagnosis and Pathophysiological Mechanisms of Group 3 Hypoxia-Induced Pulmonary Hypertension

PURPOSE OF REVIEW

Group 3 hypoxia-induced pulmonary hypertension (PH) is an important and increasingly diagnosed condition in both the pediatric and adult population. The majority of pulmonary hypertension studies to date and all three classes of drug therapies were designed to focus on group 1 PH. There is a clear unmet medical need for understanding the molecular mechanisms of group 3 PH and a need for novel non-invasive methods of assessing PH in neonates.

RECENT FINDINGS

Several growth factors are expressed in patients and in animal models of group 3 PH and are thought to contribute to the pathophysiology of this disease. Here, we review some of the findings on the roles of vascular endothelial growth factor A (VEGFA), platelet-derived growth factor B (PDGFB), transforming growth factor-beta (TGFB1), and fibroblast growth factors (FGF) in PH. Additionally, we discuss novel uses of echocardiographic parameters in assessing right ventricular form and function. FGF2, TGFB, PDGFB, and VEGFA may serve as biomarkers in group 3 PH along with echocardiographic methods to diagnose and follow right ventricle function. FGFs and VEGFs may also function in the pathophysiology of group 3 PH.

Non-invasive imaging of global and regional cardiac function in pulmonary hypertension

Pulmonary hypertension (PH) is a progressive illness characterized by elevated pulmonary artery pressure; however, the main cause of mortality in PH patients is right ventricular (RV) failure. Historically, improving the hemodynamics of pulmonary circulation was the focus of treatment; however, it is now evident that cardiac response to a given level of pulmonary hemodynamic overload is variable but plays an important role in the subsequent prognosis. Non-invasive tests of RV function to determine prognosis and response to treatment in patients with PH is essential. Although the right ventricle is the focus of attention, it is clear that cardiac interaction can cause left ventricular dysfunction, thus biventricular assessment is paramount. There is also focus on the atrial chambers in their contribution to cardiac function in PH. Furthermore, there is evidence of regional dysfunction of the two ventricles in PH, so it would be useful to understand both global and regional components of dysfunction. In order to understand global and regional cardiac function in PH, the most obvious non-invasive imaging techniques are echocardiography and cardiac magnetic resonance imaging (CMRI). Both techniques have their advantages and disadvantages. Echocardiography is widely available, relatively inexpensive, provides information regarding RV function, and can be used to estimate RV pressures. CMRI, although expensive and less accessible, is the gold standard of biventricular functional measurements. The advent of 3D echocardiography and techniques including strain analysis and stress echocardiography have improved the usefulness of echocardiography while new CMRI technology allows the measurement of strain and measuring cardiac function during stress including exercise. In this review, we have analyzed the advantages and disadvantages of the two techniques and discuss pre-existing and novel forms of analysis where echocardiography and CMRI can be used to examine atrial, ventricular, and interventricular function in patients with PH at rest and under stress.

Prospective validation of right ventricular role in primary graft dysfunction after lung transplantation

Primary graft dysfunction is a significant cause of lung transplant morbidity and mortality, but its underlying mechanisms are not completely understood. The aims of the present study were: 1) to confirm that right ventricular function is a risk factor for severe primary graft dysfunction; and 2) to propose a clinical model for predicting the development of severe primary graft dysfunction.A prospective cohort study was performed over 14 months. The primary outcome was development of primary graft dysfunction grade 3. An echocardiogram was performed immediately before transplantation, measuring conventional and speckle-tracking parameters. Pulmonary artery catheter data were also measured. A classification and regression tree was made to identify prognostic models for the development of severe graft dysfunction.70 lung transplant recipients were included. Patients who developed severe primary graft dysfunction had better right ventricular function, as estimated by cardiac index (3.5±0.8 versus 2.6±0.7 L·min^-1·m^-2, p<0.01) and basal longitudinal strain (-25.7±7.3% versus -19.5±6.6%, p<0.01). Regression tree analysis provided an algorithm based on the combined use of three variables (basal longitudinal strain, pulmonary fibrosis disease and ischaemia time), allowing accurate preoperative discrimination of three distinct subgroups with low (11-20%), intermediate (54%) and high (75%) risk of severe primary graft dysfunction (area under the receiver operating characteristic curve 0.81).Better right ventricular function is a risk factor for the development of severe primary graft dysfunction. Preoperative estimation of right ventricular function could allow early identification of recipients at increased risk, who would benefit the most from careful perioperative management in order to limit pulmonary overflow.

Fast assessment of long axis strain with standard cardiovascular magnetic resonance: a validation study of a novel parameter with reference values

BACKGROUND

Assessment of longitudinal function with cardiovascular magnetic resonance (CMR) is limited to measurement of systolic excursion of the mitral annulus (MAPSE) or elaborate strain imaging modalities. The aim of this study was to develop a fast assessable parameter for the measurement of long axis strain (LAS) with CMR.

METHODS

40 healthy volunteers and 125 patients with different forms of cardiomyopathy were retrospectively analyzed. Four different approaches for the assessment of LAS with CMR measuring the distance between the LV apex and a line connecting the origins of the mitral valve leaflets in enddiastole and endsystole were evaluated. Values for LAS were calculated according to the strain formula.

RESULTS

LAS derived from the distance of the epicardial apical border to the midpoint of the line connecting the mitral valve insertion points (LAS-epi/mid) proved to be the most reliable parameter for the assessment of LAS among the different approaches. LAS-epi/mid displayed the highest sensitivity (81.6 %) and specificity (97.5 %), furthermore showing the best correlation with feature tracking (FTI) derived transmural longitudinal strain (r = 0.85). Moreover, LAS-epi/mid was non-inferior to FTI in discriminating controls from patients (Area under the curve (AUC) = 0.95 vs. 0.94, p = NS). The time required for analysis of LAS-epi/mid was significantly shorter than for FTI (67 ± 8 s vs. 180 ± 14 s, p < 0.0001). Additionally, LAS-epi/mid performed significantly better than MAPSE (Delta AUC = 0.09; p < 0.005) and the ejection fraction (Delta AUC = 0.11; p = 0.0002). Reference values were derived from 234 selected healthy volunteers. Mean value for LAS-epi/mid was -17.1 ± 2.3 %. Mean values for men were significantly lower compared to women (-16.5 ± 2.2 vs. -17.9 ± 2.1 %; p < 0.0001), while LAS decreased with age.

CONCLUSIONS

LAS-epi/mid is a novel and fast assessable parameter for the analysis of global longitudinal function with non-inferiority compared to transmural longitudinal strain.

Right ventricular strain in pulmonary arterial hypertension: a 2D echocardiography and cardiac magnetic resonance study

BACKGROUND

Right ventricular (RV) strain is a potentially useful prognostic marker in patients with pulmonary arterial hypertension (PAH). However, published reports regarding the accuracy of two-dimensional echocardiography (2DE)-derived RV strain against an independent reference in this patient population are limited. The aims of this study were: (1) to study the relationship between 2DE RV longitudinal strain and cardiovascular magnetic resonance (CMR)-derived RV ejection fraction (RVEF) in patients with PAH; (2) to compare 2DE-derived and CMR-derived RV longitudinal strain in these patients; and (3) to determine the reproducibility of these measurements.

METHODS

Thirty patients with PAH underwent 2DE and CMR imaging within a 2-hour time period. 2DE RV longitudinal strain was measured from a focused RV apical four-chamber view using speckle tracking software. CMR RV longitudinal strain was measured from short-axis slices acquired using fast-strain-encoded sequence. Global peak systolic RV longitudinal strain was calculated for both 2DE and CMR.

RESULTS

RV longitudinal strain using 2DE software correlated well with CMR-derived RVEF (R = 0.69, P = 0.0006). There was moderate agreement when comparing 2DE to CMR RV longitudinal strain (R = 0.74, P = 0.0002; bias -1%, limits of agreement -9 to 7%). Inter-observer variability and intra-observer variability for RV longitudinal strain were lower for 2DE than CMR.

CONCLUSIONS

RV longitudinal strain by 2DE provides a good alternative for CMR-derived RVEF in patients with PAH. The moderate agreement in strain measurements between 2DE and CMR suggests that further software improvements are needed before these measurements can be used interchangeably in clinical practice.

Echocardiography in pediatric pulmonary hypertension

Pediatric pulmonary hypertension is a complicated disease with multiple etiologies and high mortality. Echocardiography is at the forefront of evaluation as a noninvasive, portable imaging modality that can yield diagnostic and prognostic information regarding this disease. Echocardiography is known for its ability to give an anatomic assessment of the heart and proximal blood vessels. With the additional use of Doppler echocardiography and myocardial motion assessment, the effects of elevated pulmonary pressures on the heart can be evaluated. This can allow for estimation of pulmonary artery pressures and resistances and assessment of ventricular systolic and diastolic functions. However despite its advantages, echocardiography is still an indirect assessment of pulmonary hypertension and not a substitute for cardiac catheterization. The purpose of this review is to discuss common techniques for the assessment of pulmonary hypertension by echocardiography as well as their limitations.

Mid-term differences in right ventricular function in patients with congenital diaphragmatic hernia compared with controls

BACKGROUND

Patients with congenital diaphragmatic hernia (CDH) may have abnormal lung development, which may cause detrimental effects on right ventricular (RV) function. This study aimed to determine if there are persistent echocardiographic differences in RV function in patients with CDH years after repair versus control patients.

METHODS

Patients who underwent repair for CDH were recruited. RV function was evaluated by strain analysis and tissue Doppler imaging (TDI). Wilcoxon's rank-sum test was used for analysis.

RESULTS

Seven CDH patients and 16 control patients were studied. There was no difference in age between the CDH and control groups (6.2±1.7 years vs. 5.7±1.7 years). TDI demonstrated significantly lower values in the RV early diastolic wave (12.8±1.5 cm/s vs. 16.1±3.1 cm/s) and RV systolic wave (10.2± 0.8cm/s vs. 13.4±1.3 cm/s) when comparing the CDH group and the control group. Interventricular apical septal strain was signifi cantly lower in the CDH group than in the control group (-20.1±4.6% vs. -25.4±4.1%). There was a trend towards lower strain values in the RV mid-lateral segment in the CDH group (-30.8±9.9% versus -39.7±6.0%, P=0.06) and a lower global RV strain (-27.8±3.0% vs. -31.1±3.1%, P=0.06).

CONCLUSIONS

Patients who underwent CDH repair continue to have differences in RV function years after repair. Follow-up is needed to determine how these differences impact cardiac function in adult survivors of CDH.

Review of MR elastography applications and recent developments

The technique of MR elastography (MRE) has emerged as a useful modality for quantitatively imaging the mechanical properties of soft tissues in vivo. Recently, MRE has been introduced as a clinical tool for evaluating chronic liver disease, but many other potential applications are being explored. These applications include measuring tissue changes associated with diseases of the liver, breast, brain, heart, and skeletal muscle including both focal lesions (e.g., hepatic, breast, and brain tumors) and diffuse diseases (e.g., fibrosis and multiple sclerosis). The purpose of this review article is to summarize some of the recent developments of MRE and to highlight some emerging applications.

Today's and tomorrow's imaging and circulating biomarkers for pulmonary arterial hypertension

The pathobiology of pulmonary arterial hypertension (PAH) involves a remodeling process in distal pulmonary arteries, as well as vasoconstriction and in situ thrombosis, leading to an increase in pulmonary vascular resistance, right heart failure and death. Its etiology may be idiopathic, but PAH is also frequently associated with underlying conditions such as connective tissue diseases. During the past decade, more than welcome novel therapies have been developed and are in development, including those increasingly targeting the remodeling process. These therapeutic options modestly increase the patients' long-term survival, now approaching 60% at 5 years. However, non-invasive tools for confirming PAH diagnosis, and assessing disease severity and response to therapy, are tragically lacking and would help to select the best treatment. After exclusion of other causes of pulmonary hypertension, a final diagnosis still relies on right heart catheterization, an invasive technique which cannot be repeated as often as an optimal follow-up might require. Similarly, other techniques and biomarkers used for assessing disease severity and response to treatment generally lack specificity and have significant limitations. In this review, imaging as well as current and future circulating biomarkers for diagnosis, prognosis, and follow-up are discussed.

Novel methods for assessment of right heart structure and function in pulmonary hypertension

Long-term increases in pulmonary vascular resistance and pulmonary arterial pressure resulting from structural alterations and abnormal vasoreactivity of the pulmonary vasculature may lead to right ventricular (RV) remodeling. Conventional methods of assessment of RV structure and function do not provide sensitive markers of RV remodeling for prognostic information. Advances in cardiac imaging have provided the capability to obtain quantitative information on the RV structure and function. This article reviews the clinical conditions that result in PH and discusses the novel and emerging methods for the assessment of right heart structure and function in PH in infants and children.

Echocardiography based estimation of pulmonary vascular resistance in patients with pulmonary hypertension: a simultaneous Doppler echocardiography and cardiac catheterization study

AIMS

Pulmonary vascular resistance (PVR) is an important measurement for the diagnosis of patients with pulmonary hypertension (PH) but needs accurate determination of mean pulmonary artery pressure (PAMP). We aimed to test the accuracy of a Doppler-derived measurement of PVR, using the conventional invasive equation in patients with PH.

METHODS AND RESULTS

We investigated 30 patients undergoing right heart catheterization (RHC), mean age 62 ± 13 years, 21 females, with different diseases; idiopathic pulmonary arterial hypertension (PAH) (n = 5), associated PAH (n = 16), chronic thromboembolic PH (n = 6), interstitial lung disease (n = 2), and after closure of an atrial septal defect (n = 1). Patients with impaired left ventricular systolic function (EF < 50%) or elevated pulmonary capillary wedge pressure (PCWP >15 mmHg on RHC) were excluded. We used the formula: PAMP = PASP(echo) × 0.61 + 2 mmHg, where PASP(echo) is the peak tricuspid regurgitation pressure drop + 10 or 7 mmHg. Pulmonary vascular resistance was then calculated as PAMP(echo)- PCWP/cardiac output. Pulmonary capillary wedge pressure was estimated at 10 mmHg in all cases. The Doppler-derived estimation of PVR(echo) was achievable in 90% of patients, in whom accurate calculation of PAMP was obtainable. Pulmonary vascular resistance echo individual values strongly correlated with those from RHC (r = 0.85, P < 0.001 and r = 0.87, P < 0.001 for the two estimated values for right atrial pressure, respectively). The regression equation using this formula was PVR(rhc) = 0.95 × PVR(echo)- 0.29, and the regression line was close to identity. The Bland-Altman plot showed a good agreement between PVR(echo) and PVR(rhc) values, with a mean difference of -0.66 ± 2.1 Wood unit.

CONCLUSION

The proposed Doppler-derived formula for estimating PVR based on the conventionally used invasive equation strongly correlates with invasive gold standard measures.