Cardiac MRI based numerical modeling of left ventricular fluid dynamics with mitral valve incorporated.

Recent numerical studies were focused on the modeling of flow in patient-specific left ventricle (LV); however, the mitral valve (MV) was usually excluded. In this study, both patient-specific LV and MV were modeled to achieve a more realistic intraventricular flow. Cardiac MRI images were acquired from a pulmonary arterial hypertension (PAH) patient and a healthy volunteer, and manual segmentation was conducted to reconstruct three-dimensional (3D) LV and MV geometries at each frame. Based on these 3D geometries, vortex formation time (VFT) was derived, and the values were 4.0 and 6.5 for the normal subject and the PAH patient, respectively. Based on studies in the literature, VTF in the healthy subject fell within the normal range, while that in the PAH patient exceeded the threshold for normality. The vortex structures in the LV clearly showed that the vortex ring was initiated from the tips of the MV instead of the mitral annulus. The excessive VFT during the rapid filling phase in the PAH patient resulted in a trailing flow structure behind the primary vortex ring, which was not observed in the normal subject. It can be deduced from this study that incorporating the MV into a patient-specific model is necessary to produce more reasonable VFT and intraventricular flow.

Surgical correction of persistent truncus arteriosus on a 33-year-old male with unilateral pulmonary hypertension from migration of pulmonary artery band.

BACKGROUND: Persistent truncus arteriosus is a rare congenital condition with which survival into adulthood is dismal without surgery. This is the oldest patient reported to our knowledge demonstrating the feasibility of assessing operability in persistent truncus arteriosus with unilateral pulmonary stenosis, and performing full corrective surgery in adulthood. CASE PRESENTATION: We report a Chinese male with successful correction of Type I persistent truncus arteriosus at 33 years of age. He had unilateral pulmonary hypertension from migration of pulmonary artery band from the main to the right pulmonary artery, severe truncal valve regurgitation from previous infective endocarditis, and progressive congestive heart failure. Improvement of lung perfusion was demonstrated 21 months post operation. CONCLUSION: This case demonstrated that in patients with persistent truncus arteriosus and two pulmonary arteries, pulmonary vascular disease or underdevelopment of one lung does not preclude a full corrective surgery so long as the other vascular bed is normal. It is important to emphasize the importance of assessing patient's operability in totality.

Molecular pathogenesis of Marfan syndrome.

Marfan syndrome (MFS) is a genetic disorder that affects multiple organs. Mortality imposed by aortic aneurysm and dissections represent the most serious clinical manifestation of MFS. Progressive pathological aortic root enlargement as the result of degeneration of microfibril architecture and consequential loss of extracellular matrix integrity due to fibrillin-1 (FBN1) mutations are commonly diagnosed clinical manifestations of MFS. However, overlapping clinical manifestations with other aneurysmal disorders present a significant challenge in early and accurate diagnosis of MFS. While FBN1 mutations, abnormal transforming growth factor-ß signaling and dysregulated matrix metalloproteinases have been implicated in MFS, clinically accepted risk-stratifying biomarkers have yet to be reliably identified. In this review, we summarize current consensus and recent insights in the understanding of MFS pathogenesis. Finally, we introduce the application of induced pluripotent stem cells (iPSCs) as cellular models for MFS and its potential as a novel platform into providing better appreciation of mechanisms underlying MFS diverse manifestations in the cardiovascular system.