Imagerie de l’hypertension artérielle pulmonaire

Detection of Pulmonary Hypertension by Combining Echocardiography and Chest Radiography

RATIONALE AND OBJECTIVES

In pulmonary hypertension (PH) patients, chest radiographs often show an increase in the diameter of the right descending pulmonary artery (RDPA). The purpose of this study is to evaluate whether a combination of echocardiography and chest radiography for detecting PH is more accurate than echocardiography alone.

MATERIALS AND METHODS

Between 2013 and 2019, a total of 1301 patients were included in this study. Among them, 1030 patients with congenital heart disease (CHD) were used to establish a linear regression model by combining echocardiographic and chest radiographic variables, and 136 CHD patients and 135 non-CHD patients were used to compare the accuracy between a new model and the 2015 ESC/ERS guidelines for right heart catheterization recommendation. The chest radiographic diameter of the RDPA, and the echocardiography-measured tricuspid regurgitation pressure gradient and the main pulmonary artery diameter were assessed.

RESULTS

The TG-RDPA composite index correlated more strongly than either the TG or RDPA (r = 0.741 vs 0.709 or 0.544; both p value <0.001). The TG-RDPA composite index was more accurate in detecting PH than the ESC/ERS 2015 guidelines (overall accuracy: 83.8% vs 77.1%; missed diagnoses rate: 12.0% vs 22.5%). The overall accuracy of the main pulmonary artery-RDPA composite index (r = 0.599, p value <0.001) was 84.1% compared to overall accuracy of 77.1% using the ESC/ERS 2015 guidelines.

CONCLUSION

A combination of echocardiography and chest X-ray may be a more accurate way to detect PH and an alternative method for suspected PH patients without tricuspid regurgitation velocity.

[Practical conduct for patients with a lonely hypoxemia at rest or during exercise]

INTRODUCTION

Hypoxemia is a decrease in blood oxygen partial pressure. This work aims at presenting a practical conduct for patients with a lonely hypoxemia at rest or during exercise, defined by the absence of dyspnea at rest, obvious clinical or radiographic abnormality.

STATE OF THE ART

Diagnostic tools available to the clinician are clinical examination, CT scan, echocardiography, hyperoxia test, trans cranial ultrasound and lung scintigraphy. This work proposes a practical diagnostic approach, with a main role of chest CT.

PERSPECTIVES

Work is underway to determine more precisely the place of echocardiography for the diagnosis of intra or extra cardiac shunts.

CONCLUSIONS

The finding of a lonely hypoxemia requires careful diagnostic approach to quickly rule out potentially serious causes and not to disregard the rare causes.

A systematic review of the diagnostic accuracy of cardiovascular magnetic resonance for pulmonary hypertension

BACKGROUND

The diagnostic accuracy of cardiovascular magnetic resonance (CMR) for pulmonary hypertension (PH) compared with right heart catheterization were assessed. The purpose of this systematic review was to comprehensively evaluate the diagnostic accuracy of CMR in evaluating PH.

METHODS

Published literature was obtained from PUBMED, Web of Knowledge, Cochrane library, Embase, Biosis Preview, China National Knowledge Infrastructure, and Chongqing VIP databases, and all studies were inclusive until December 2012. Studies relevant to PH and its imaging in CMR and right heart catheterization were included if correlation coefficient was elucidated clearly. Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) score was used to assess the quality of studies. Sensitivity and specificity were pooled separately and compared with overall accuracy measures: diagnostic odds ratio and symmetric summary receiver operating characteristic.

RESULTS

Sixteen studies were included in the systematic review. Of all the studies, the most widely used index was ventricular mass index (VMI) of CMR. We performed a meta-analysis for VMI among 429 patients in 5 individual studies, which showed a modest diagnostic accuracy of VMI for PH with a summary sensitivity and specificity of 84% (95% confidence interval, 79%-87%) and 82% (95% confidence interval, 73%-89%), respectively. In addition, the summary positive likelihood ratio was 4.894, indicating that VMI of CMR allows a modest ability to distinguish PH patients from healthy subjects with a cutoff point of 0.45 using functional and structural measures.

CONCLUSIONS

This systematic review and meta-analysis indicates that VMI seems to have a moderate sensitivity and specificity for detection of PH. The application values of other parameters still need further investigation.

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.

Routine Chest X-ray: Still Valuable for the Assessment of Left Ventricular Size and Function in the Era of Super Machines?

Objectives:

The development of technologically advanced, expensive techniques has progressively reduced the value of chest X-ray in clinical practice for the assessment of left ventricular (LV) dilatation and dysfunction. Although controversial data are reported on the role of this widely available technique in cardiac assessment, it is known that the cardio-thoracic ratio is predictive of risk of progression in the NYHA Class, hospitalization, and outcome in patients with LV dysfunction. This study aimed to evaluate the reliability of the transverse diameter of heart shadow [TDH] by chest X-ray for detecting LV dilatation and dysfunction as compared to Magnetic Resonance Imaging (MRI) performed for different clinical reasons.

Materials and Methods:

In 101 patients, TDH was measured in digital chest X-ray and LV volumes and ejection fraction (EF) by MRI, both exams performed within 2 days.

Results:

A direct correlation between TDH and end-diastolic volumes (r = .75, P<0.0001) was reported. TDH cut-off values of 14.5 mm in females identified LV end-diastolic volumes >150 mL (sensitivity: 82%, specificity: 69%); in males a cut-off value of 15.5 mm identified LV end-diastolic volumes >210 mL (sensitivity: 84%; specificity: 72%). A negative relation was found between TDH and LVEF (r = -.54, P<0.0001). The above cut-off values of TDH discriminated patients with LV systolic dysfunction – LVEF <35% (sensitivity and specificity: 67% and 57% in females; 76% and 59% in males, respectively).

Conclusions:

Chest X-ray may still be considered a reliable technique in predicting LV dilatation by the accurate measurement of TDH as compared to cardiac MRI. Technologically advanced, expensive, and less available imaging techniques should be performed on the basis of sound clinical requests.

[Investigation of pulmonary hypertension]

Pulmonary hypertension (PH) is defined by a mean pulmonary artery pressure (PAPm) superior than 25mmHg at rest or superior than 30mmHg with exercise. The classification of PH differentiates between "secondary" PH which results from a well-known disease, such as PH due to thromboembolic disease (obstructive PH), left cardiac failure (passive PH), or chronic respiratory diseases (hypoxic PH), and pulmonary arterial hypertension (PAH). PAH is a rare disease characterized by a progressive increase of pulmonary vascular resistance leading to right ventricular failure. PAH is classified as idiopathic, familial, or associated with various conditions (connective tissue diseases, congenital heart diseases with systemic-to-pulmonary shunts, portal hypertension, infection with the human immunodeficiency virus, or appetite-suppressant drugs). Transthoracic Doppler echocardiography is the investigation of choice for non invasive detection of PAH but right-heart catheterization is necessary to confirm the diagnosis of PAH and determine its mechanism. Pulmonary function tests and chest CT scan may detect an underlying chronic pulmonary disease (hypoxic PH). Lung perfusion scan and contrast-enhanced chest spiral CT scan can lead to the diagnosis of thromboembolic PH, which is to be confirmed by pulmonary angiography. Assessment of the severity of PH is based on clinical parameters (NYHA, right heart failure), functional tests (six-minute walk test), echocardiography and hemodynamics. Characterization of PH is essential in the management of PH because it determines the appropriate treatment: an etiological treatment in passive, obstructive or hypoxemic PH, or vasodilatator and antiproliferative therapies in PAH.