ABSTRACT
T = P × R. ( 14.1)
Here t he w all ten sion i s e xpressed i n ter ms o f ten sion (T) p er unit of cross-sectional area [dynes per centimeter (dyn/cm)], P is pressure (dyn/cm2), and R is the radius (cm). So, the wall tension is proportional to radius. e wall thickness must be taken into consideration when the equation is applied for the cardiac ventricles. Because of the thick ventricular walls, wall tension is distributed over a large number of muscle bers, thereby reducing
tension on each. e equation for a thick-walled cylinder (heart) is described by the Equation 14.2:
T = P × R_____ h
, (14.2)
where h is the wall thickness. From t he de scribed rel ationship s tems t hat t he ten sion o n
the v entricular w alls i ncreases a s v entricular c avity vol ume increases, e ven if in traventricular p ressure r emains c onstant (ventricular dilation). er efore, a erload is increased whenever intraventricular p ressures a re i ncreased d uring s ystole a nd b y ventricular dilation. On the other hand, the tension is reduced, even as pressure r ises, a s t he ventricle empties or t he ventricle wall i s t hickened a nd h ypertrophied. us, v entricular w all hypertrophy can be thought of as an adaptive mechanism of the ventricle to o set increase in wall tension caused by increased aortic pressure or aortic valve stenosis.
