Physical fitness, dynamic extra-arterial pressures, and the pathogenesis and distribution of atherosclerosis

Medical writings on cardiovascular disease focus on intravascular pressures. Tissue pressure is assumed to be essentially atmospheric. Yet, under dynamic conditions of sitting, standing, walking, breathing, and the beating of the heart, significant pressures, both above and below atmospheric, do develop outside of important arteries. These dynamic extra-arterial pressures either decrease or increase the pressure gradients across arterial walls, i.e. the transmural pressures are changed. Physical fitness may either prevent the development of negative extra-arterial pressure or increase positive extra-arterial pressure, thereby protecting important arteries from high effective pressures. Deconditioning, old age, abdominal obesity, and other cardiovascular disease risk factors may do just the opposite, in effect, causing 'localized hypertension' in clinically important arteries. This, in turn, may lead to localized acceleration of atherosclerosis. The correlation of predictions made from this hypothesis with clinical findings is so remarkable that it suggests there is a direct cause and effect relationship between transmural arterial pressure and atherosclerosis. The concept of dynamic extra-arterial pressure seems to solve a number of puzzles and paradoxes in cardiovascular disease, it suggests key measurements that may be predictive of disease, and it offers new ideas for treatment and prevention.