Page 153 - Assessing right ventricular function and the pulmonary circulation in pulmonary hypertension Onno Anthonius Spruijt

Introduction
Precapillary pulmonary hypertension (PH) is characterized by an increase in pulmonary vascular resistance (PVR) and right ventricular (RV) adaption to the increased load is one of the main determinants of patient outcome [1]. A well-established method to non-invasively characterize the myocardium is the assessment of late gadolinium enhancement (LGE) by cardiac magnetic resonance imaging (CMRI). Previous studies in PH patients showed delayed enhancement of the interventricular insertion regions [2-5] and linked this phenomenon to focal fibrosis [4, 6]. In addition, LGE was shown to correlate with disease severity [2, 4, 5]. A major drawback of the assessment of LGE is the need for the administration of the contrast agent gadolinium. Its toxicity due to depositions in other parts of the body, for example in the brain [7], is not completely understood, but gadolinium administration is contra-indicated in patients with renal insufficiency. Moreover, the LGE technique is not suitable to detect more diffuse myocardial pathologies since the calculation of the threshold of abnormal enhancement depends on a reference area of myocardium [8]. An alternative technique to characterize the myocardium is native T1-mapping. T1-mapping quantifies the T1 relaxation time per pixel tissue and different tissues show a characteristic range of T1-values [9-11]. Native T1-values increase when the heart is affected by edema and diffuse or focal fibrosis [12-20]. To quantify native T1-values, there is no need for a reference area of myocardium, making it possible to directly quantify the total myocardium. Moreover, native T1-values can be determined without the use of contrast agents [10]. Therefore, the aim of this study was to characterize the myocardium of idiopathic pulmonary arterial hypertension (IPAH), systemic scleroderma related PH (PAH-Ssc) and chronic thromboembolic PH (CTEPH) patients using native T1- mapping and to see whether native T1-values were related to disease severity. Furthermore, since the difference in presence of histologically confirmed myocardial fibrosis between these forms of precapillary PH vary between studies [21-23], we compared native T1-values between the different precapillary PH categories.
Methods
Subjects
We retrospectively analyzed all available native T1-mapping data of IPAH patients (n=46), PAH-SSc patients (n=14) and CTEPH patients (n=10) scanned between June 2011 and March 2014 in the VU University Medical Center. Data was acquired in the context of an ongoing prospective research
Chapter 9
151
9