460 HEALTH AND DISEASE 



tion of the cavity, without any alteration in the thickness of the walls, the 

 diastolic sound is longer than normal, while the systolic is shortened. 



The pathologist also obtains a great deal of information while examin- 

 ing his patient by comparing the sounds which are heard in different parts 

 of the chest, especially over those parts which correspond to the lower part 

 or apex and the upper part or base of the heart. If the sounds are weak 

 at the apex and louder at the base, the evidence is accepted as serving 

 to distinguish effusion into the heart-sac (pericardium) from dilatation of 

 the cavities or fatty condition of the heart. Intense sound at the right 

 apex over and above that at the left may indicate either displacement 

 or enlargement of the right side of the heart; it also occurs when a portion 

 of lung unduly distended with air (emphysematous) is interposed between 

 the heart and the walls of the chest. 



A murmur or, as it is commonly called, " bruit " is generally taken 

 to indicate friction at some point over which the blood is passing, and 

 in the majority of cases it is allowed that the murmur depends on 

 some morbid condition of the valves which guard the orifices of the 

 heart. 



There are certain situations in which the murmurs relating to different 

 parts of the heart are most readily heard. Thus murmurs connected with the 

 mitral valves (fig. 191) are described as loudest just above the apex beat, 

 while the murmurs which are connected with the valves of the aorta are 

 most marked at the base of the heart. In the descriptions which are given 

 in works on pathology a much more intricate and extended account of the 

 different sounds in different positions is given, but sufficient has been 

 written to indicate to the reader the very abstract character of the subject, 

 and the enormous difficulties which attend a critical examination of the 

 heart with a view of making a correct diagnosis of any existing disease. 

 Indeed, with all the facilities which the physician possesses, including 

 the use of the most elaborate and perfect instruments, the power to 

 place his patient in any position which he thinks most convenient, and 

 of regulating the character of the respirations with regard to their depth 

 and frequency, or of arresting the action altogether for a short period, 

 so as to obtain absolute silence in the respiratory organs of the chest, 

 there is still a considerable difference of opinion existing among experts 

 as to the cause and meaning of certain sounds which can be recognized. 



Diseases of the heart and its connections are for convenience divided 

 into those which affect the membranes enclosing and lining the organ, and 

 those attacking the muscular structure of which it is chiefly composed. 

 Thus we have acute or chronic inflammation of the membranous sac in the 

 double layer of which the heart is completely invested, and similar affec- 



