RESULTS 



Figure 3 shows the Beg recorded 

 from Gigi. In amplitude and form, it 

 is similar to that seen in man. Figure 

 4 demonstrates that the inlluence of 

 ventilation on the tracing is profound. 

 In fact, during expiration and in- 

 spiration reading the Beg is impossible. 



Figure 5 displays the Begs of 

 three animals — a mouse, a man. and a 

 whale. Their similarities are more 

 striking than their differences. This 

 similarity holds in spite of differences 

 in body mass and form, amount and 

 distribution of fat. and natural 

 environment. 



Table 1 lists some measurements 

 derived from the Bcg's of the mouse, 

 man. and a whale. It also gives some 

 fundamental values which are helpful 

 in comparing the species. 



The Beg has been used to estimate 

 cardiac output and stroke volume in 

 several species. By using the Starr 

 formula (Starr and Noordergraaf. 

 1967. p. 177- 180) we estimated Gigi's 

 stroke volume to be 7.2 I. and the 

 cardiac output as .^08 1/min (Table I). 



DISCUSSION 



One of the major postulated objec- 

 tions to the Beg is that the amount 

 and distribution of body fat can con- 

 siderably alter the recording. This 

 did not seem to be the ease in Gigi. 

 in spite of a 3' 2 inch layer of 

 blubber. It is true that the old direct- 

 body Beg used in the 1950's was 

 subject to influence by body fat. How- 

 ever, the ultra low-frequency bed. by 

 virtue of its light weight and strong 

 coupling between subject and bed. 

 has eliminated most of this inaccuracy. 

 The fundamental natural frequency 

 of the body ("bowl of jelly" phenom- 

 enon alluded to by some in refer- 

 ence to the Beg) does not depend on 

 bod\ mass, amount of fat. or age 

 (Burger. Noordergraaf. and Ver- 

 hagen. 1953; Burger and Noorder- 

 graaf. 1956; Talbot and Harrison. 

 1955; Tannenbaum. Vessell. and 

 Schaek. 1956; Weissbaek. 1960a. 

 1960b; Tischenko. 1963). Some of 



Figure 2. — Gigi. Beg bed. man. and hoist. The accelerometer is being attached to the right side 

 of the proximal pole. The truck was jammed against the retaining wall of the tank. A white rope 

 strung across the tank supports the cables. 



the higher mode frequencies may 

 depend on the amount and distribu- 

 tion of body fat. 



A crucial factor in ballistocardiog- 

 raphy is the orientation of the aorta 

 in relation to the body. This is so 

 because usually complexities have 

 forced ballistocardiographers to 



record the Beg in one dimension, the 

 head-foot direction, instead of the 

 possible three dimensions and six 

 degrees of freedom. Thus if the 

 direction of ejection and runoff is 

 different in different species, the com- 

 parison would be difficult. The orienta- 

 tion of the aorta seems to be no 



11 



