The use of pericardial sac as a cardiometer--a technique for recording the effects of DRUGS ON HEART IN SITU.

When one is interested in the study, particularly the screening, of cardioactive agents, one needs to have the information on the effects of the concerned drug on (i) the rate, (ii) rhythm, (iii) force of contraction and (iv) output of the heart. The methods commonly used to study the effects of drugs on the heart in situ are Cushny's myocardiograph, glass cardiometry and electrocardiography (3). Cushny 's myocardiography gives dependable information on the force and the rate of contraction of both auricles and the ventricles but volume changes can not be studied. The electrocardiography records information on the rate and the rhythm of auricles and ventricles. But it can not be routinely employed particularly in the screening of cardioactive agents. Moreover, it does not give any information regarding the cardiac output and the force of contraction. The glass cardiometry provides information regarding the ventricular volume changes, the rate of ventricles and perhaps indirectly the force of contraction. It may also provide some gross information regarding the presence of some irregularity. Thus, of the three commonly employed methods, the glass cardiometry appears to give a greater information about the drug effect on the heart. It was thought whether the principle of glass cardiometry which is applicable to ventricles only, can be extended to the entire heart by putting a cannula in the pericardial sac. We therefore wish to report the working of this technique. We have not so far come across any reference to this technique in the literature.