346 PECULIARITIES OF THE CARDIAC MUSCLE TISSUE 



The ability of cardiac muscle to increase its substance is of great dynamical 

 importance, because in the absence of this compensation grave circulatory dis- 

 orders would result. In illustration of this statement, attention might briefly be 

 called to the different lesions of the cardiac valves, which may persist for many 

 years without serious impairment of the circulation. A stenotic condition of one 

 or the other of the cardiac orifices commonly produces a hypertrophic condition of 

 that part of the heart which forces the blood through this opening. In this way, 

 the supply of blood to the compartment situated distally to the obstruction may 

 be kept practically the same for many years. This is also true in a way of regur- 

 gitation, because the continuous stretching of the cardiac chamber by the regurgi- 

 tating blood serves as a stimulus for its elements to contract more forcibly. In 

 both cases the arterial pressure and flow remain practically normal until the 

 primary lesion has developed sufficiently to exceed the limit of this physiological 

 compensation. 



