Structural, molecular and functional characterization of the aorta in HCM

Introduction

Changes in the Extracellular Matrix (ECM) in Hypertrophic Cardiomyopathy (HCM) is thought to involve the myocardium as well as extracardiac tissues. The extent and significance of extra-myocardial changes has not been adequately studied.

Purpose

To describe the structural, molecular, and functional changes in the aorta of HOCM patients.

Methods

The structural and molecular changes in the aortic wall were studied in a cohort of 102 consecutive patients with hypertrophic obstructive cardiomyopathy undergoing myectomy. The biopsies were examined histologically, immunohistochemically and by Electron microscopy. The findings were compared to 10 normal controls obtained from the homograft bank of the Harefield hospital, following IRB guidelines. Changes in expression were quantified using morphometry and western blotting. For aortic stiffness, pulse wave velocity [PWV] was measured using Cardiac Magnetic Resonance (CMR), in the 102 HCM patients as well as age-matched 166 normal controls.

Results

Specimens from HCM aortas showed a misalignment in collagen and elastin fibres. There was a significant reduction in smooth muscle cells [SMCs] markers; integrin beta1 and smooth muscle actin, and an increase in an apoptosis marker, Caspase3. In addition, there was a significant decrease in the number of lamellae and an increase in the interlamellar distance in HCM aortas. FBLNs 1, 2 and 5 showed a reduction in expression in tunica intima and tunica media of HCM biopsies. PWV was significantly higher in HCM patients compared to healthy controls with the highest levels in patients with LV fibrosis.

Conclusion

This study illustrates the link between functional abnormalities in the aorta of HCM patients with structural and molecular changes. These findings can have a potential value in risk stratification and identify new therapeutic targets in HCM.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): STDF-EgyptMagdi Yacoub Foundation

1093 Multi-modality imaging of a rare cause of constrictive physiology: pericardial ring

Introduction

Proper pathophysiologic diagnosis of constrictive pericarditis (CP) usually mandates utilization of multiple diagnostic tools.

We report a rare cause of constrictive pericarditis in a 33-year-old female presenting with painful epigastric pulsations, easy fatigability, and lower limb edema of 6 months duration. The patient had no past history of trauma, cardiac surgery, or tuberculosis.

Trans-thoracic echocardiography (figure 1, panels A, parasternal long-axis view, and B, apical 4-chamber view) showed an echogenic band (arrow head) across the left (LV) and right (RV) ventricles, with compressed RV cavity. Septal bounce, with shifting of the inter-ventricular septum towards the LV during deep inspiration, was noted; however, Doppler evaluation of the diastolic function was not conclusive of constriction.

Cardiac magnetic resonance (figure 1, panel C) and computed tomography with 3D segmentation, using Materialise Mimics and 3-matic software (figure 1, panel D),showed an 8-mm thick, calcified pericardial ring (arrow head) encircling and indenting both ventricles at mid-cavitary level, resulting in bi-ventricular compression and dumbbell-shaped heart. Both ventricles were of average cavity size, with preserved LV size, systolic function and mildly impaired RV systolic function. Right heart catheterization confirmed the diagnosis of constrictive pericarditis. The patient was referred for surgical pericardiectomy.

Conclusion

Multi-modality imaging is integral for the diagnosis of CP. Our case represents a rare etiology of constrictive physiology.

Abstract 1093 Figure 1