Age-Related Histologic Features of the Sinus Node in Normal Human Hearts during the First 10 Decades of Life: A Study of 200 Cases
Christine M Keeney, Mathieu C Castonguay, William D Edwards, Joseph J Maleszewski. Mayo Clinic, Rochester, MN
Background: Age-related histologic features of the normal human sinus node have not been reported in large studies. It is thought that nodal collagen progressively increases as humans age, based mainly on small case series.
Design: 200 formalin-fixed grossly normal human hearts, obtained at autopsy from subjects without heart disease, were retrieved from the tissue archives of Mayo Clinic in Rochester, MN. For each of the first 10 decades of life, 20 hearts (10 from males and 10 from females) were selected. The sinus nodes were dissected from the right atria and processed for histology. 4 um-thick tissue sections were stained with Verhoeff-van Gieson, and, photomicrographs taken of the section of node with that largest cross-sectional area. Analysis was performed on the chosen section using ImageJ 1.44 (NIH, USA), evaluating for the following parameters: area of the sinus node (in mm2), percent collagen, percent fat, average diameter of nodal myocytes, and average diameter of contractile atrial myocytes. Relationships with age and gender were also investigated.
Results: A significant cubic association was identified between mean sinus nodal area and age (p = 0.0008). Linear associations were seen between nodal myocyte diameters and between contractile myocyte diameters and age after the first decade (p = 0.006 and 0.008, respectively), and were most pronounced for contractile myocyte diameters. There were no associations between nodal collagen content (median = 22.5%, IQR = 17.8 – 27.0%) and age, nor between fat content (median = 0%, IQR = 0 – 0%) and age. Significant inter-individual variation was noted in these parameters. Adjusting for body mass index and body surface area did not influence these results.
Conclusions: This is the largest and only series to date describing the appearance of the normal human sinus node evenly divided throughout the first 10 decades of life. It contradicts the long-standing belief that nodal collagen content increases with age, which is of special relevance to evaluation of the conduction system in cases of sudden death. Significant associations between nodal area, nodal myocyte diameter, contractile myocyte diameter, and age were identified, despite significant inter-individual variation in these parameters – this variation should be borne in mind on a case-by-case basis.
Wednesday, March 21, 2012 1:00 PM
Poster Session VI # 39, Wednesday Afternoon