730 HANDBOOK OF PHYSIOLOGY ^^ CIRCULATION I 



ivo noD ^^^^^^^^^f ^^^^w^^^^^^^^^pHi ^^^^wi^^^^^^^^^R^ ^^^^"^^Pf^^^^^^Pjf i^^^»^^^^^^^^^WT 1".^^^*^^^^ 



liiiu: 



?C(Bft 



FIG. 14. Intracardiac phonocardiogram, illustrating the use of this technique in the correlation of 

 acoustic events with hemodynamics. These recordings were taken from a 30-year-old female with 

 rheumatic heart disease with both mitral stenosis and tricuspid stenosis. The recording shows from 

 above downward: the chest phonocardiogram from the fifth intercostal space at the right sternal 

 border (5ics RSB) (where the tricuspid murmur could be heard best), the intracardiac phonocardio- 

 gram from the inflow tract of the right ventricle (RV), lead II of the electrocardiogram, right atrial 

 pressure (RA), and right ventricular pressure (RV). The pressures were recorded from the same 

 base line with identical calibrations. Note that at the point at which ventricular pressure falls below 

 atrial pressure a murmur begins in the right ventricle which continues up to the time at which right 

 ventricular pressure rises above right atrial pressure. With an increase in the gradient of pressure 

 across the valve late in diastole with atrial contraction there is an increase in the intensity of the 

 murmur. Not shown here is the mitral diastolic murmur from within the cavity of the left ventricle 

 which had a different configuration than this murmur originating at the tricuspid valve. 



CU_. 



The technique of intracardiac piionocardiography 

 has certain advantages as well as certain disad- 

 vantages. Its great value lies in its ability to record 

 the events from close to their site of origin. This not 

 only provides a means of direct comparison with 

 other events of the cardiac cycle but also provides a 

 means for studying transmission through the thoracic 

 tissues to the chest wall. In addition, intracardiac 

 phonocardiography has proved of great value in 

 that it has the ability to localize sharply the produc- 

 tion of sounds and murmin-s. This feature, which, 

 perhaps, could not have been predicted prior to the 

 actual observations, appears to be clue to tiie damping 

 characteristics of the structures invohed, including 

 the blood. The details of this parameter are as yet 

 incompletely understood. From the records obtained 

 it is clear that the intracardiac transmission of the 

 various events differs. For example, it is not unusual 

 to record aortic valve closiue with the transducer 

 located in the outflow tract of the right ventricle. It is 

 decidedly unusual to record an aortic diastolic 

 murmur here. In general, there appears to be wider 

 transmission within the heart and circulation of 



sounds than of murmurs. Indeed the localization of 

 murmurs may be quite precise. For example, in 

 ventricular septal defect with a left-to-right shimt, 

 cases have been seen in which the murmur was well 

 recorded in only part of the right ventricle, and not in 

 another part. This fascinating feature not only 

 provides a powerful physiological tool for delineating 

 flow patterns secondary to intracardiac lesions, but 

 also has added a new cardio\ascular diagnostic tool. 

 In situations in which murtniir localization can pro- 

 vide the clue to the site of the lesion, intracardiac 

 phonocardiography appears to provide information 

 unequaled by any other method. Figures 1 1 through 

 15 illustrate some of the types of information that can 

 be obtained with intracardiac phonocardiography. 



Certain problems also arise. The technique re- 

 quires cardiac catheterization and although, in our 

 hands, it does not add to the risks, it does not reduce 

 them either. The problem of artifacts produced by 

 the catheter is a real one. That such artifacts can be 

 produced by any cardiac catheter and be of suHicient 

 intensity to be audible on the chest wall has been 

 verv clearh- pointed out by Eldridge & Hultgren 



