Echocardiographic diagnosis and clinical implications of wide-open tricuspid regurgitation for evaluating right ventricular dysfunction in the emergency department

The tricuspid regurgitation pressure gradient (TRPG) reflects the difference in pressure between the right ventricle and right atrium (ΔPRV-RA). Its estimation by echocardiography correlates well with that obtained using right-heart catheterization. An elevated TRPG is an important marker for identifying right ventricular dysfunction in both the acute and chronic settings. However, in the "wide-open" variant of TR, the TRPG counterintuitively falls. Failure to recognize this potential pitfall and underlying pathophysiology can cause underestimation of the severity of right ventricular dysfunction. This could lead to erroneous fluid tolerance assessments, and potentially harmful resuscitative and airway management strategies. In this manuscript, we illustrate the pathophysiology and potential pitfall of wide-open TR through a series of cases in which emergency physicians made the diagnosis using cardiac point-of-care ultrasound. To our knowledge, this clinical series is the first to demonstrate recognition of the paradoxically-low TRPG of wide-open TR, which guided appropriate management of critically ill patients in the emergency department.

Echocardiography in Pulmonary Arterial Hypertension: Comprehensive Evaluation and Technical Considerations

Pulmonary arterial hypertension (PAH) is a rare, progressive disease in which there is a persistent, abnormal increase in pulmonary artery pressure. Symptoms of pulmonary hypertension are nonspecific and mainly associated with progressive right ventricular failure. The diagnosis of PAH is a multistep process and often requires the skillful use of several tests. The gold standard for the diagnosis of PAH is hemodynamic testing. Echocardiography currently plays an important role in the diagnostic algorithm of PAH as it is minimally invasive and readily available. Moreover, many echocardiographic parameters are closely related to pulmonary hemodynamics. It allows assessment of the right heart′s structure and function, estimation of the pressure in the right ventricle, right atrium, and pulmonary trunk, and exclusion of other causes of elevated pulmonary bed pressure. Echocardiographic techniques are constantly evolving, and recently, measurements made using new techniques, especially 3D visualization, have become increasingly important. In echocardiographic assessment, it is crucial to know current guidelines and new reports that organize the methodology and allow standardization of the examination. This review aims to discuss the different echocardiographic techniques used to evaluate patients with PAH.

Pulmonary hypertension secondary to pulmonary fibrosis: clinical data, histopathology and molecular insights

Pulmonary hypertension (PH) developing secondarily in pulmonary fibrosis (PF) patients (PF-PH) is a frequent co-morbidity. The high prevalence of PH in PF patients is very concerning since the presence of PH is a strong predictor of mortality in PF patients. Until recently, PH was thought to arise solely from fibrotic destruction of the lung parenchyma, leading to hypoxic vasoconstriction and loss of vascular bed density. Thus, potential cellular and molecular dysregulation of vascular remodeling as a driver of PF-PH has been under-investigated. The recent demonstrations that there is no correlation between the severity of the fibrosis and development of PH, along with the finding that significant vascular histological and molecular differences exist between patients with and without PH have shifted the etiological paradigm of PF-PH. This review aims to provide a comprehensive translational overview of PH in PF patients from clinical diagnosis and outcome to the latest understanding of the histology and molecular pathophysiology of PF-PH.

Invasive and Noninvasive Evaluation for the Diagnosis of Pulmonary Hypertension: How to Use and How to Combine Them

The etiologic diagnosis of pulmonary hypertension (PH) may be very challenging. Right-heart catheterization (RHC) in isolation cannot classify a precapillary PH patient into group 1, 3, 4, or 5. Moreover, RHC may be not sufficient for reaching a definitive differential diagnosis of precapillary or postcapillary PH if hemodynamic data are not integrated in clinical context and combined with information gleaned from noninvasive imaging. Therefore, only the integration of risk factors, clinical evaluation, invasive and noninvasive tests allows the physician to distinguish between different forms of PH.

Changes in acute pulmonary vascular responsiveness to hypoxia during a progressive ascent to high altitude (5300 m)

NEW FINDINGS

What is the central question of this study? Do the pulmonary vascular responses to hypoxia change during progressive exposure to high altitude and can alterations in these responses be related to changes in concentrations of circulating biomarkers that affect the pulmonary circulation? What is the main finding and its importance? In our field study with healthy volunteers, we demonstrate changes in pulmonary artery pressure suggestive of remodelling in the pulmonary circulation, but find no changes in the acute responsiveness of the pulmonary circulation to changes in oxygenation during 2 weeks of exposure to progressive hypoxia. Pulmonary artery pressure changes were associated with changes in erythropoietin, 8-isoprostane, nitrite and guanosine 3',5'-cyclic monophosphate. We sought to determine whether changes in pulmonary artery pressure responses to hypoxia suggestive of vascular remodelling occur during progressive exposure to high altitude and whether such alterations are related to changes in concentrations of circulating biomarkers with known or suspected actions on the pulmonary vasculature during ascent. We measured tricuspid valve transvalvular pressure gradients (TVPG) in healthy volunteers breathing air at sea level (London, UK) and in hypoxic conditions simulating the inspired O₂ partial pressures at two locations in Nepal, Namche Bazaar (NB, elevation 3500 m) and Everest Base Camp (EBC, elevation 5300 m). During a subsequent 13 day trek, TVPG was measured at NB and EBC while volunteers breathed air and hyperoxic or hypoxic mixtures simulating the inspired O₂ partial pressures at the other locations. For each location, we determined the slope of the relationship between TVPG and arterial oxygen saturation (SaO2) to estimate the pulmonary vascular response to hypoxia. Mean TVPG breathing air was higher at any SaO2 at EBC than at sea level or NB, but there was no change in the slope of the relationship between SaO2 and TVPG between locations. Nitric oxide availability remained unchanged despite increases in oxidative stress (elevated 8-isoprostane). Erythropoietin, pro-atrial natriuretic peptide and interleukin-18 levels progressively increased on ascent. Associations with TVPG were observed only with erythropoietin, 8-isoprostane, nitrite and guanosine 3',5'-cyclic monophosphate. Although the increased TVPG for any given SaO2 at EBC suggests that pulmonary vascular remodelling might occur during 2 weeks of progressive hypoxia, the lack of change in the slope of the relationship between TVPG and SaO2 indicates that the acute pulmonary vascular responsiveness to changes in oxygenation does not vary within this time frame.

Pulmonary Artery Acceleration Time Provides a Reliable Estimate of Invasive Pulmonary Hemodynamics in Children

BACKGROUND

Pulmonary artery acceleration time (PAAT) is a noninvasive method to assess pulmonary hemodynamics, but it lacks validity in children. The aim of this study was to evaluate the accuracy of Doppler echocardiography-derived PAAT in predicting right heart catheterization (RHC)-derived pulmonary artery pressure (PAP), pulmonary vascular resistance (PVR), and compliance in children.

METHODS

Prospectively acquired and retrospectively measured Doppler echocardiography-derived PAAT and RHC-derived systolic PAP, mean PAP (mPAP), indexed PVR (PVRi), and compliance were compared using regression analysis in a derivation cohort of 75 children (median age, 5.3 years; interquartile range, 1.3-12.6 years) with wide ranges of pulmonary hemodynamics. To account for heart rate variability, PAAT was adjusted for right ventricular ejection time and corrected by the RR interval. Regression equations incorporating PAAT and PAAT/right ventricular ejection time from the derivation cohort were then evaluated for the accuracy of their predictive values for invasive pulmonary hemodynamics in a validation cohort of 50 age- and weight-matched children with elevated PAP and PVR.

RESULTS

There were significant inverse correlations between PAAT and RHC-derived mPAP (r = -0.82) and PVRi (r = -0.78) and a direct correlation (r = 0.78) between PAAT and pulmonary compliance in the derivation cohort. For detection of pulmonary hypertension (PRVi > 3 Wood units · m² and mPAP > 25 mm Hg), PAAT < 90 msec and PAAT/right ventricular ejection time < 0.31 resulted in sensitivity of 97% and specificity of 95%. In the derivation cohort, the regression equations relating PAAT with mPAP and PVRi were mPAP = 48 - 0.28 × PAAT and PVRi = 9 - 0.07 × PAAT. These PAAT-integrated equations predicted RHC-measured pulmonary hemodynamics in the validation cohort with good correlations (r = 0.88 and r = 0.83, respectively), small biases (<10%), and minimal coefficients of variation (<8%).

CONCLUSIONS

PAAT inversely correlates with RHC-measured pulmonary hemodynamics and directly correlates with pulmonary arterial compliance in children. The study established PAAT-based regression equations in children to accurately predict RHC-derived PAP and PVR.

Advanced echocardiography for the critical care physician: part 2

This article is the second part of a series that describes practical techniques in advanced critical care echocardiography and their use in the management of hemodynamic instability. Measurement of left ventricular function and segmental wall motion abnormalities, evaluation of left ventricular filling pressures, assessment of right-sided heart function, and determination of preload sensitivity, including passive leg raising, are discussed. Video examples help to demonstrate techniques described in the text.

Evaluation of cardiac functions with Doppler echocardiography in children with Down syndrome and anatomically normal heart

OBJECTIVE

To study the cardiac functions in Down syndrome children who did not have structural cardiac lesion by conventional and tissue Doppler echocardiography.

MATERIALS AND METHODS

A total of 85 children with Down syndrome without anatomic heart disease and 50 normal control children were subjected to the assessment of right and left ventricular functions by both two-dimensional and tissue Doppler echocardiography.

RESULTS

Children with Down syndrome had significantly higher left ventricular ejection fraction detected by two-dimensional echocardiography and left ventricular diastolic dysfunction detected by tissue Doppler than observed in the controls. In addition, children with Down syndrome also had right ventricular systolic and diastolic dysfunctions. Children with Down syndrome had significantly higher pulmonary artery systolic pressure than the control children. There was no significant difference in the cardiac functions between children with non-disjunction Down syndrome and those with the translocation type.

CONCLUSION

Despite an apparently normal heart, children with Down syndrome may have silent disturbed cardiac functions, which may be detected by two-dimensional or tissue Doppler echocardiography. This may have an important clinical implication, especially before involving Down syndrome children in surgery or strenuous exercise.