Age as a modulator of coronary capillary angiogenesis.

Ahalf century ago Roberts and Wearn' published their classical study on human hearts, which demonstrated that 1) capillaries multiply during postnatal growth to compensate for the increase in muscle fiber size, 2) muscle-to-capillary ratio attains a value of approximately 1:1 at maturity, and 3) this ratio persists throughout life. They also found that hypertrophied hearts of adults consistently had lower capillary densities than hearts that were not hypertrophied. Since that time, the prevailing view has been that cardiac hypertrophy in humans is accompanied by little or no capillary growth. However, the article by Rakusan and colleagues2 that appears in this issue of Circulation is the first to systematically document capillary parameters with regard to postnatal growth and pressure-overload hypertrophy in humans. There are several important new findings in this paper that provide insights into coronary angiogenesis.