Left Ventricular Hypertrophy Revisited
Cell and Matrix Expansion Have Disease-Specific Relationships
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Left ventricular hypertrophy (LVH), a common pathway in health and disease, occurs because of cellular hypertrophy and expansion of extracellular matrix. Myocardial biopsy can identify extracellular matrix expansion (fibrosis, amyloid) from cellular hypertrophy and disarray and infiltration (iron, amyloid, inflammatory cells), but its invasive nature restricts its use to specific cases. Histology recognizes these cellular (cell death/hypertrophy) and extracellular matrix (fibrosis/infiltration) processes, but conventional cardiac imaging combines them into 1 compartment: the left ventricular mass (LVM).
Cardiovascular magnetic resonance (CMR) using T1 mapping can split LVM into cellular and matrix components by measuring the extracellular volume fraction (ECV). The cell volume is LVM/1.05×[1–ECV], and the matrix volume is LVM/1.05×ECV, 1.05 being the specific gravity of the myocardium. We used this approach to explore the biology of LVH.
The study was approved by the ethical committee of the UK National Research Ethics Service (07/H0715/101) and conformed to the principles of the Helsinki Declaration. All subjects gave written consent to participate; 190 subjects underwent CMR, including healthy volunteers (HV; n=30, male 44%, 41±11 years of age, no cardiovascular history, and …