Pulmonary arterial hypertension: use of delayed contrast-enhanced cardiovascular magnetic resonance in risk assessment

Regular Risk Assessment in Pulmonary Arterial Hypertension - A Whistleblower for Hidden Disease Progression

Despite developments in the treatment of pulmonary arterial hypertension, timely treatment is seldom achieved, and hidden progression is not uncommonly disguised as a seemingly "stable" condition. Appropriate risk assessment tools facilitate goal-oriented treatment strategies. This article aimed to review the development of these risk assessment tools including early assessment equations/scores, European guidelines-based risk assessment scores, and tools derived from the United States nationwide registry. A stepwise and regular approach with these assessment tools in clinical practice is highly recommended for timely treatment escalation to stop disease progression early. In this review, a practical and recommended algorithm of these assessment tools is also provided.

A Clinical Approach to Multimodality Imaging in Pulmonary Hypertension

Pulmonary hypertension (PH) is a clinical condition characterized by progressive elevations in mean pulmonary artery pressures and right ventricular dysfunction, associated with significant morbidity and mortality. For resting PH to develop, ~50-70% of the pulmonary vasculature must be affected, suggesting that even mild hemodynamic abnormalities are representative of advanced pulmonary vascular disease. The definitive diagnosis of PH is based upon hemodynamics measured by right heart catheterization; however this is an invasive and resource intense study. Early identification of pulmonary vascular disease offers the opportunity to improve outcomes by instituting therapies that slow, reverse, or potentially prevent this devastating disease. Multimodality imaging, including non-invasive modalities such as echocardiography, computed tomography, ventilation perfusion scans, and cardiac magnetic resonance imaging, has emerged as an integral tool for screening, classifying, prognosticating, and monitoring response to therapy in PH. Additionally, novel imaging modalities such as echocardiographic strain imaging, 3D echocardiography, dual energy CT, FDG-PET, and 4D flow MRI are actively being investigated to assess the severity of right ventricular dysfunction in PH. In this review, we will describe the utility and clinical application of multimodality imaging techniques across PH subtypes as it pertains to screening and monitoring of PH.

[Possibilities of Magnetic Resonance Tomography in Diagnosis of Pulmonary Arterial Hypertension]

The emergence of more effective methods for treatment of pulmonary arterial hypertension (PAH) has called for more reliable methods of diagnostics, monitoring, and evaluating responses to the treatment. More reports have become available about the relevance of using magnetic resonance imaging (MRI) for examination of patients with PAH. This review provides data on the significance of MRI for noninvasive evaluation of the heart structure and function in patients with PAH, as well as for visualization and evaluation of the remodeling of the pulmonary circulation. According to the data presented in this review, the results obtained with various, modern MRI technologies can be used for monitoring the effect of treatment and for risk stratification in patients with PAH.

Assessment of Right Ventricular Function in Pulmonary Hypertension with Multimodality Imaging

Pulmonary hypertension (PH) is defined as resting mean pulmonary artery pressure ≥ 25 mmHg and is caused by multiple etiologies including heart, lung or other systemic diseases. Evaluation of right ventricular (RV) function in PH is very important to plan treatment and determine prognosis. However, quantification of volume and function of the RV remains difficult due to complicated RV geometry. A number of imaging tools has been utilized to diagnose PH and assess RV function. Each imaging technique including conventional echocardiography, three-dimensional echocardiography, strain echocardiography, computed tomography and cardiac magnetic resonance imaging has-advantages and limitations and can provide unique information. In this article, we provide a comprehensive review of the utility, advantages and shortcomings of the multimodality imaging used to evaluate patients with PH.

Modulators of right ventricular apoptosis and contractility in a rat model of pulmonary hypertension

AIMS

Right ventricular (RV) failure is the major cause of death among patients with pulmonary arterial hypertension (PAH). However, the mechanism of RV failure has not been defined.

METHODS AND RESULTS

This study examined mechanisms and consequences of RV myocyte apoptosis and fibrosis in response to PAH. Rats were injected with SU5416 (vascular endothelial growth factor inhibitor), followed by hypoxia for 3 weeks, and subsequently maintained in normoxia for 2, 5, or 14 weeks (5-, 8-, and 17-week time points after the SU5416 injection, respectively). RV systolic pressure (RVSP) was elevated to >70 mmHg at 5-week time point, and this pressure was sustained thereafter. Significant RV myocyte apoptosis and fibrosis were observed at 8- and 17-week time points. Apoptosis was associated with downregulated Bcl-xL (anti-apoptotic protein), downregulated GATA4 (transcriptional regulator of Bcl-xL), and upregulated p53 (negative regulator of GATA4 gene transcription). PAH-mediated RV apoptosis and fibrosis were attenuated in p53 knock-out rats. Despite the major loss of cardiomyocytes, RV contractility was enhanced, suggesting that the remaining myocytes can perform improved contractile functions. Improved RV contractility is associated with the increased expression of contractile and sarcoplasmic reticulum Ca(2+) uptake proteins. In contrast, the expression of calsequestrin 2 (CSQ2) was downregulated. The siRNA knockdown of CSQ2 improved RV contractility and increased the expression of contractile and Ca(2+) uptake proteins.

CONCLUSION

These results suggest that RV decompensation is associated with the death of cardiomyocytes, resulting in fibrosis. However, the remaining myocytes are capable of sustaining RV contractility through the mechanism that involves CSQ2.