CARDIAC PAIN — BREATIILESSNESS. 17 



uneasiness to the most intense agony in angina pectoris. This 

 is, indeed, what we find, for a heart whose nutrition has been 

 weakened by disease of its arteries, and consequent imperfect 

 supply of blood to the cardiac muscle, is unable to meet any 

 increased resistance if this should be offered to it, and pain is at 

 once felt. In such cases, unless they be far advanced, we find, 

 precisely as we might expect, that walking on the level usually 

 causes no pain, but the attempt to ascend even a slight rise, by 

 which the muscles are brought into more active exertion, brings 

 on pain at once. Yet here again we find, as we should expect, 

 that if the patient is able to continue walking, the pain passes 

 off and does not return. These phenomena would be inexplic- 

 able were it not for Ludwig's observations on circulation through 

 the muscles, but in the lioht of these observations evervthini? 



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is made perfectly intelligible. "Walking on the flat, by causing 

 no violent exertion of the muscles, produces no mechanical con- 

 striction of the vessels, and thus does not increase the blood 

 pressure. The greater exertion of walking up a hill has this 

 effect, but if the patient is able to continue his exertions, the 

 increased dilatation of the vessels — a consequence of muscular 

 activity — allows the pressure again to fall and relieves the pain. 

 As muscular exertion continues and the vessels of the muscles 

 become dilated, the flow of blood from the arteries into the veins 

 will tend to become much more rapid than usual. The pressure 

 in the arterial system will consequently fall, but that in the 

 veins will become increased, and unless a corresponding dilata- 

 tion occurs in the pulmonary circulation, blood will tend to 

 accumulate in the right side of the heart, the right ventricle 

 will be unable to empty itself completely, shortness of breath 

 will arise, and even death may occur. At first the right side of 

 the heart is affected, and the apex beat disappears from its 

 normal place and is felt in the epigastrium. But the left 

 ventricle also becomes dilated, though whether this is simply 

 through nervous influence tending to make it act concordantly 

 with the right, or for some other reason, it is at present 

 impossible to say. Severe exertions, even for a few minutes, 

 may produce this condition in healthy persons,* and when the 



• Scliolt, Ycrbandl. de ix. Congresses iwMed. zu JFien, ISCO. 



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