472 MODERN DEVELOPMENTS OF HARVEY's WORK. 



becoiue more rigid aud less capable of dilating and allowing freer flow 

 of blood to any part whether it be the intestine, the skin, the brain, the 

 muscles, or the heart itself. Mere rigidity of the arteries supplying the 

 muscles of the heart will lessen the power of extra exertion, but if the 

 vessels be not only rigid, but diminished in caliber, the muscles of tlie 

 limbs and the heart itself will be unfit even for their ordinary Avork, and 

 will tend to fail on the slightest overexertion. This fact was noticed 

 by Sir Benjamin Brodie, who, when speaking of patients with degener- 

 ating and contracted arteries, such as lead to senile gangrene, said: 



"Such patients walk a short distance very well, but when they attempt 

 more than this the muscles seem to be unequal to the task, and they 

 can walk no farther. The muscles are not absolutely paralyzed, but 

 in a state approaching to it. The cause of all this is sufficiently obvi- 

 ous. Tlie lower limbs require sometimes a larger and sometimes a 

 smaller supi)ly of blood. During exercise a large supply is wanted on 

 account of the increased action of the muscles; but the arteries being 

 ossified or obliterated, and thus incapable of dilatation, the increased 

 supidy can not be obtained. This state of things is not j>eculiar to the 

 lower limbs. Wherever muscular structures exist the same cause will 

 l)roduce the same effect. Dr. Jenner first, and Dr. Parry, of Bath, 

 afterwards, published observations which were suijposed to prove that 

 the disease which is usually called angina pectoris dei)ends on ossifica- 

 tion of the coronary arteries. - - - When the coronary arteries are 

 in this condition they may be capable of admitting a moderate supply 

 of blood to the muscular structure of the heart, and as long as the 

 l)atient makes no abnormal exertion the circulation goes on well enough; 

 when, however, the heart is excited to increased action, whether it be 

 during a fit of passion, or in running, or walking upstairs, or lifting 

 weights, then the ossified arteries being incapable of expanding so as to 

 let in the additional quantity of blood, which under these circumstances 

 is re(juired, its action stops and syncoi)e ensues; and I say that this 

 exactly corresponds to the sense of weakness and want of muscular 

 ]>ower which exists in i^ersons who have thearteries of thelegs obstructed 

 or ossified.*'' 



But the syncope and stoppage of the lieart mentioned b}* Brodie are 

 not the only consequences of impaired cardiac nutrition. The heart 

 may be still able to carry on the circulation, but the patient may suffer 

 intense pain in the process. The outside of the heart was found by 

 Harvey to be insensible to light touches, but the inside of the heart 

 ai)pears to be much more sensitive either to touch or pressure. 



A knowledge of the mode of circulation of blood through the muscles 

 enables us to understand uot only the pathology of angina pectoris, 

 but the rationale of various methods of treating patients sufiering 

 from angina pectoris or other forms of heart disease. In most cases our 

 object is a twofold one — to increase the power of the heart and to lessen 

 the resistance it has to overcome. In some cases we require also to aid 

 the elimination of water which has so accumulated as to give rise to 

 oedema of the cellular tissues or dropsy of the serous cavities. In our 



'Lectures on Pathology and Surgery, by Sir Boujaruin Brodie, London, 1846, 

 page 360. 



