550 FUNCTIONAL DISORDERS OF THE HEART. 



CHAPTER XXVII. 



FUNCTIONAL DISORDERS OF THE HEART. 



I. Palpitation. 



Under this group is intended to be placed such disturbances 

 of the normal activities of the heart as are believed to be un- 

 connected with alterations of structure. The consideration of 

 these is chiefly important from the resemblance which dis- 

 turbance of this character bears to structural change, and 

 from the difficulty which so often exists in distinguishing 

 between these very different conditions. 



The usual form in which functional disturbance of the heart 

 presents itself to our notice is that of palpitation — tumultuous 

 and irregular cardiac action, sometimes associated with peculiar 

 cardiac sounds, and irregular character of the heart's action and 

 of the arterial pulsations. These symptoms, from the frequency 

 of their occurrence and their connection with organic disease 

 of the heart, derive an importance which they would not other- 

 wise command, seeing that of themselves, and apart from this 

 association, they are, as a rule, not of serious moment. 



Causation. — This disturbance of the rhythmic action of the 

 heart and of its functional activity is the result of various 

 causes acting upon the system generally or upon the heart 

 individually, (a) It may occur in connection with disease, 

 acute or chronic, of the heart or its covering, inducing de- 

 fective power ; or from obstruction at some of the orifices, 

 which its muscular exertion cannot overcome, (b) It is occa- 

 sionally associated with disease of the lungs, in which the 

 power of the organ is overcome by pulmonary obstruction, 

 (c) Changes in the quantity or quality of the blood, as anosmia, 

 plethora, or special contaminations, may induce this disturb- 

 ance. This latter effect is observed in certain specific, consti- 

 tutional, and epizootic diseases, (d) Influences operating 

 through the nervous system have the power to produce similar 

 results. These may be intrinsic, centric, or reflex. These 

 latter are observed in intestinal disturbances, acute or chronic, 

 with the existence of which they are closely bound up, usually 

 disappearing when they are removed. 



The former, besides being in many instances rather occult 



