Cardiac MRI as a diagnostic tool in pulmonary hypertension

Diverse Right Ventricular Remodeling Evaluated by MRI and Prognosis in Eisenmenger Syndrome With Different Shunt Locations

BACKGROUND

Congenital shunt location is related to Eisenmenger syndrome (ES) survival. Moreover, right ventricular (RV) remodeling is associated with poor survival in pulmonary hypertension.

PURPOSE

To investigate RV remodeling using comprehensive magnetic resonance imaging (MRI) techniques and identify its relationship with prognosis in ES subgroups classified by shunt location.

STUDY TYPE

Prospective observational study.

POPULATION

Fifty-four adults with ES (16 with pre-tricuspid shunt and 38 with post-tricuspid shunt).

FIELD STRENGTH/SEQUENCE

3.0 T/cine MRI with balanced steady-state free precession sequence, late gadolinium enhancement with inversion recovery segmented gradient echo sequence and phase-sensitive reconstruction, and T1 mapping with modified Look-Locker inversion recovery sequence.

ASSESSMENT

Demographics, clinical characteristics, hemodynamics, RV remodeling features (morphology, systolic function, RV-pulmonary artery (PA) coupling and myocardial fibrosis), and prognosis were compared between ES subgroups. The adverse endpoint was all-cause mortality or readmission for heart failure.

STATISTICAL TESTS

The independent samples t-test, Fisher's exact test or Chi-squared test, and the Kaplan-Meier method were used. P < 0.05 was considered significant.

RESULTS

Compared to patients with post-tricuspid shunt, patients with pre-tricuspid shunt were significantly older and had higher N-terminal pro-B-type natriuretic peptide concentrations and poorer exercise tolerance. Pre-tricuspid shunt showed significantly larger RV dimensions (end-diastolic volume index: 185.81 ± 37.49 vs. 98.20 ± 36.26 mL/m² ), worse RV ejection fraction (23.54% ± 12.35% vs. 40.82% ± 10.77%), and RV-PA decoupling (0.35 ± 0.31 vs. 0.72 ± 0.29). Biventricular myocardial fibrosis was significantly more severe in pre-tricuspid shunt than post-tricuspid shunt (extracellular volume, left ventricle: 35.85% ± 2.58% vs. 29.10% ± 5.20%; RV free wall: 30.93% ± 5.65% vs. 26.75% ± 5.15%). In addition, pre-tricuspid shunt demonstrated a significantly increased risk of adverse endpoint (hazard ratio: 2.938, 95% confidence interval: 1.204-7.172).

DATA CONCLUSION

ES with pre-tricuspid shunt might be a unique subtype with worse clinically decompensated RV remodeling and poor prognosis.

LEVEL OF EVIDENCE

2 Technical Efficacy Stage: 5.

Prognostic Value of Cardiac Magnetic Resonance–Derived Right Ventricular Remodeling Parameters in Pulmonary Hypertension

Background

Cardiac right ventricular remodeling plays a substantial role in pathogenesis, progression, and prognosis of pulmonary hypertension. Cardiac magnetic resonance is considered an excellent tool for evaluation of right ventricle. However, value of right ventricular remodeling parameters derived from cardiac magnetic resonance in predicting adverse events is controversial.

Methods

The Pubmed (MEDLINE), Embase, Cochrane Library, Web of Science, China National Knowledge Infrastructure platform (CNKI), China Science and Technology Journal Database (VIP), and Wanfang databases were systematically searched until November 2019. Studies reporting hazard ratios (HRs) for all-cause death and composite end point of pulmonary hypertension were included. Univariate HRs were extracted from the included studies to calculate pooled HRs of each right ventricular remodeling parameter.

Results

Eight studies with 1120 patients examining all-cause death (female: 44%–92%, age: 40–67 years old, follow-up time: 27–48 months) and 10 studies with 604 patients examining composite end point (female: 60%–83%, age: 29–57 years old, follow-up time: 10–68 months) met the criteria. Right ventricular ejection fraction was the only parameter which could predict both all-cause death (pooled HR=0.95; P =0.014) and composite end point (pooled HR=0.95; P <0.001), although right ventricular end-diastolic volume index (pooled HR=1.01; P <0.001), right ventricular end-systolic volume index (pooled HR=1.01, P =0.045), and right ventricular mass index (pooled HR=1.03, P =0.032) only predicted composite outcome. Similar results were observed when we conducted the meta-analysis among patients with World Health Organization type I of pulmonary hypertension.

Conclusions

Cardiac magnetic resonance–derived right ventricular remodeling parameters have independent prognostic value for all-cause death and composite end point of patients with pulmonary hypertension. Right ventricular ejection fraction was the strongest prognostic factor among all the right ventricular remodeling parameters. Right ventricular mass index, right ventricular end-diastolic volume index, and right ventricular end-systolic volume index also demonstrated prognostic value.

The importance of right ventricular function in patients with pulmonary arterial hypertension

INTRODUCTION

Pulmonary arterial hypertension (PAH) is a progressive, life-threatening, and incurable disease. Its prognosis is based on right ventricular (RV) function. Therefore, adequate assessment of RV function is mandatory. Areas covered: This article presents the case of a patient with PAH in which the traditional diagnostic approach did not provide a complete assessment of RV function. The authors show how the analysis of other parameters yielded additional information that improved the management of this patient. Expert commentary: Despite current treatments, PAH often worsens due to progressive RV dysfunction. Appropriate assessment of RV function may facilitate the early identification of patients at risk of RV function impairment. More aggressive treatment of PAH might delay progression of the disease. Traditional risk stratification, which is based on New York Heart Association/World Health Organization (NYHA/WHO) functional class evaluation, the 6-minute walk test, and right heart catheterization, proves insufficient in many PAH patients, as it does not provide complete information about RV function. Thus, further parameters are required. Analysis of RV function, in addition to echocardiography and cardiopulmonary exercise testing, may add relevant prognostic information and improve therapy.

ACR Appropriateness Criteria® Suspected Pulmonary Hypertension

Pulmonary hypertension may be idiopathic or related to a large variety of diseases. Various imaging examinations that may be helpful in diagnosing and determining the etiology of pulmonary hypertension are discussed. Imaging examinations that may aid in the diagnosis of pulmonary hypertension include chest radiography, ultrasound echocardiography, ventilation/perfusion scans, CT, MRI, right heart catheterization, pulmonary angiography, and fluorine-18-2-fluoro-2-deoxy-d-glucose PET/CT. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Pulmonary hypertension in the premature infant: a challenging comorbidity in a vulnerable population

PURPOSE OF REVIEW

This review is written from the perspective of the pediatric clinician involved in the care of premature infants at risk for pulmonary hypertension. The main objective is to better inform the clinician in the diagnosis and treatment of pulmonary hypertension in premature infants by reviewing the available relevant literature and focusing on the areas for which there is the greatest need for continued research.

RECENT FINDINGS

Continued knowledge regarding the epidemiology of pulmonary hypertension in the premature infant population has aided better diagnostic screening algorithms. Included in this knowledge, is the association of pulmonary hypertension in infants with bronchopulmonary dysplasia (BPD). However, it is also known that beyond BPD, low birth weight and other conditions that result in increased systemic inflammation are associated with pulmonary hypertension. This information has led to the recent recommendation that all infants with BPD should have an echocardiogram to evaluate for evidence of pulmonary hypertension prior to discharge from the neonatal ICU.

SUMMARY

Pulmonary hypertension can be a significant comorbidity for premature infants. This review aims to focus the clinician on the available literature to improve recognition of the condition to allow for more timely interventions.

Non-invasive measurement using cardiovascular magnetic resonance of changes in pulmonary artery stiffness with exercise

BACKGROUND

Exercise stress tests are commonly used in clinical settings to monitor the functional state of the heart and vasculature. Large artery stiffness is one measure of arterial function that can be quantified noninvasively during exercise stress. Changes in proximal pulmonary artery stiffness are especially relevant to the progression of pulmonary hypertension (PH), since pulmonary artery (PA) stiffness is the best current predictor of mortality from right ventricular failure.

METHODS

Cardiovascular magnetic resonance (CMR) was used to investigate the effect of exercise stress on PA pulse wave velocity (PWV) and relative area change (RAC), which are both non-invasive measures of PA stiffness, in healthy subjects. All 21 subjects (average age 26 ± 4 years; 13 female and 8 male) used a custom-made MR-compatible stepping device to exercise (two stages of mild-to-moderate exercise of 3-4 min duration each) in a supine position within the confines of the scanner. To measure the cross-sectional area and blood flow velocity in the main PA (MPA), two-dimensional phase-contrast (2D-PC) CMR images were acquired. To measure the reproducibility of metrics, CMR images were analyzed by two independent observers. Inter-observer agreements were calculated using the intraclass correlation and Bland-Altman analysis.

RESULTS

From rest to the highest level of exercise, cardiac output increased from 5.9 ± 1.4 L/min to 8.2 ± 1.9 L/min (p < 0.05), MPA PWV increased from 1.6 ± 0.5 m/s to 3.6 ± 1.4 m/s (p < 0.05), and MPA RAC decreased from 0.34 ± 0.11 to 0.24 ± 0.1 (p < 0.05). While PWV also increased from the first to second exercise stage (from 2.7 ± 1.0 m/s to 3.6 ± 1.4 m/s, p < 0.05), there was no significant change in RAC between the two exercise stages. We found good inter-observer agreement for quantification of MPA flow, RAC and PWV.

CONCLUSION

These results demonstrate that metrics of MPA stiffness increase in response to acute moderate exercise in healthy subjects and that CMR exercise stress offers great potential in clinical practice to noninvasively assess vascular function.

Assessment of Pulmonary Arterial Hypertension by Magnetic Resonance Imaging

Pulmonary arterial hypertension (PAH) is characterized by elevated pulmonary artery pressure (PAP), altered pulmonary artery (PA) hemodynamics, and vessel wall characteristics that affect the right ventricular (RV) function. Magnetic resonance imaging (MRI) has recently been considered in PAH and has shown promising results for estimating PAP, measuring PA hemodynamic parameters, assessing PA vessel wall stiffness, and evaluating RV global and regional functions. In this article, we review various MRI techniques and image analysis methods for evaluating PAH, with an emphasis on the resulting images and how they are interpreted for both qualitatively and quantitatively assessing the PA and RV conditions.