Multimodality Imaging in Pulmonary Hypertension

Cardiovascular Magnetic Resonance in Right Heart and Pulmonary Circulation Disorders

Right heart and pulmonary circulation disorders are generally caused by right ventricle (RV) pressure overload, volume overload, and cardiomyopathy, and they are associated with distinct clinical courses and therapeutic approaches, although they often may coexist. Cardiac magnetic resonance (CMR) provides a noninvasive accurate and reproducible multiplanar anatomic and functional assessment, tissue characterization, and blood flow evaluation of the right heart and pulmonary circulation. This article reviews the current status of the CMR, the most recent techniques, the new parameters and their clinical utility in diagnosis, prognosis, and therapeutic management in the right heart and pulmonary circulation disorders.

Approach to Pulmonary Hypertension: From CT to Clinical Diagnosis

Pulmonary hypertension (PH) is a condition characterized by increased pressure in the pulmonary circulation. It may be idiopathic or arise in the setting of other clinical conditions. Patients with PH tend to present with nonspecific cardiovascular or respiratory symptoms. The clinical classification of PH was recently revised at the World Health Organization symposium in Nice, France, in 2013. That consensus statement provided an updated classification based on the shared hemodynamic characteristics and management of the different categories of PH. Some features seen at computed tomography (CT) can suggest a subtype or probable cause of PH that may facilitate placing the patient in the correct category. These features include findings in the pulmonary arteries (peripheral calcification, peripheral dilatation, eccentric filling defects, intra-arterial soft tissue), lung parenchyma (centrilobular nodules, mosaic attenuation, interlobular septal thickening, bronchiectasis, subpleural peripheral opacities, ground-glass opacities, diffuse nodules), heart (congenital lesions, left heart disease, valvular disease), and mediastinum (hypertrophied bronchial arteries). An approach based on identification of these CT features in patients with PH will allow the radiologist to play an important role in diagnosis and help guide the clinician in management of PH. ^©RSNA, 2018.

Evaluation of two-dimensional strain echocardiography for quantifying right ventricular function in patients with pulmonary arterial hypertension

The aim of the current study was to evaluate the use of two-dimensional strain echocardiography (2DS) in quantifying right ventricular (RV) function in patients with pulmonary arterial hypertension (PAH). A total of 41 patients with PAH and 40 healthy control patients were recruited to the study. 2DS was used to determine the strain (ε) and strain rate (SR) of basal, middle and apical segments of the RV free wall. The aforementioned indicators were compared with measurements of RV function taken by conventional ultrasound and right heart catheterization. The ε and SR of all segments of the right ventricular free wall were significantly lower in the PAH group, as compared with the control group (P<0.05). In the PAH group, the ε and SR of the middle and apical segments were significantly lower compared with basal segments (P<0.01). The SR of the apical segments were positively correlated with the area and diameter of the right ventricular. The ε of the apical segments were positively correlated with RV area, diameter and systolic function. The ε and SR of apical segments were positively correlated with pulmonary artery pressure and pulmonary vascular resistance measured by right heart catheterization. These findings indicated that 2DS can accurately evaluate RV longitudinal systolic function.

The impact of age and gender on right ventricular diastolic function among healthy adults

BACKGROUND

Doppler echocardiography is ideally suited for assessment of diastolic function, being widely available, non-invasive, and less expensive than other techniques. However, data regarding age- and gender-matched reference values of right ventricular diastolic function are limited. This study aims to explore the physiologic variations of right ventricle (RV) diastolic function in a large cohort of healthy adults, and to investigate clinical and echocardiographic correlates.

METHODS

From June 2007 to February 2014, 1168 healthy Caucasian subjects [mean age 45.1±15.6 years, range 16-92; 555 (47.5%) men] underwent comprehensive transthoracic echocardiography (TTE) following current guidelines. The following RV main diastolic measurements were measured: peak early inflow velocity (E), annular both early (e') and atrial (a') velocities, E/e' ratio.

RESULTS

RV E/e' constantly increases with age in females, but do not change substantially in males. RV E/A constantly decreases with age in both genders. Stepwise multiple linear regression analysis underlined a close significant association of RV diastolic function with both right and left heart morphologic measurements (right atrial area, RV diameters, left atrial volume) and functional indexes (TAPSE, RV tissue Doppler peak systolic velocity, left ventricular E/Ee'), as well as with indexes of increased pulmonary resistance.

CONCLUSION

Our data highlight the potential usefulness of different normal reference values according to the age and gender to correctly evaluate RV diastolic function. Differences in terms of demographic and anthropometric parameters could be useful to avoid potential misclassification of RV diastolic function when based on dichotomously suggested normal cut-off values.

Right heart catheterisation: best practice and pitfalls in pulmonary hypertension

Right heart catheterisation (RHC) plays a central role in identifying pulmonary hypertension (PH) disorders, and is required to definitively diagnose pulmonary arterial hypertension (PAH). Despite widespread acceptance, there is a lack of guidance regarding the best practice for performing RHC in clinical practice. In order to ensure the correct evaluation of haemodynamic parameters directly measured or calculated from RHC, attention should be drawn to standardising procedures such as the position of the pressure transducer and catheter balloon inflation volume. Measurement of pulmonary arterial wedge pressure, in particular, is vulnerable to over- or under-wedging, which can give rise to false readings. In turn, errors in RHC measurement and data interpretation can complicate the differentiation of PAH from other PH disorders and lead to misdiagnosis. In addition to diagnosis, the role of RHC in conjunction with noninvasive tests is widening rapidly to encompass monitoring of treatment response and establishing prognosis of patients diagnosed with PAH. However, further standardisation of RHC is warranted to ensure optimal use in routine clinical practice.

Echocardiography in pulmonary hypertension

PURPOSE OF REVIEW

Pulmonary hypertension is a progressive disease of the pulmonary vasculature characterized by increased vascular resistance and pressure overload of the right ventricle. This review aims to describe the diagnostic and prognostic role of echocardiography in pulmonary hypertension with particular consideration of relative strengths, weaknesses and new advances.

RECENT FINDINGS

Although right heart catheterization (RHC) remains the gold standard, echocardiography represents an accessible and feasible real-world tool for screening, differential diagnostic, follow-up assessments and risk stratification in pulmonary hypertension. In the context of clinical scenario and multimaging approach, echocardiography provides accurate measurements of pulmonary haemodynamics, either at rest and/or during exercise, and is particularly useful in ruling out secondary causes of pulmonary hypertension and/or detecting preclinical stages. The use of advanced noninvasive imaging techniques may provide additional information in assessing right heart structure and function.

SUMMARY

Advances in echocardiography and the multimodality imaging approach continue to provide new understandings and opportunities for the study of the right heart-pulmonary circulation unit in pulmonary hypertension.

The Role of Echocardiography in the Evaluation of Pulmonary Arterial Hypertension

The evaluation of pulmonary arterial hypertension (PAH) requires a multimodality approach that combines invasive and noninvasive imaging studies to ensure accurate diagnosis and classification. Given the complexity of the hemodynamic relationships between the left heart, pulmonary circulation, and right heart, the diagnosis of PAH is often a challenging task. Right heart catheterization is the gold standard for diagnosis, providing the hemodynamic information that defines the disease. Nonetheless, echocardiography continues to be a valuable tool in the approach to the patient with suspected PAH. Echocardiographic assessment generates a wealth of information about the response of the right heart to elevated pulmonary pressures and provides essential diagnostic and prognostic data to the clinician. Numerous measurements can be used to identify alterations in right heart morphology, pressure, and function; although each variable in isolation may have little utility, meaningful information is revealed when multiple parameters are considered together. In this article, we will review the echocardiographic measurements employed in assessment of the right heart and seek to clarify the role of echocardiography in the diagnostic workup of PAH.