coupling, or by disease states, than by 

 differences in species. Figure 6 gives 

 an example of this. It compares a 

 virtually normal Beg in a dog with the 

 Beg in a dog at the terminal stages of 

 rejection. The latter tracing is obvious- 

 ly grossly abnormal and demonstrates 

 the extreme in Beg abnormality. 

 Other conditions which can cause a 

 greater ballistocardiographic variation 

 within than among species include 

 anginal attacks, severe coronary 

 artery disease. hyperthyroidism. 

 aortic valvular insufficiency, and 

 congestive heart failure (Starr and 

 Noordergraaf. 1967). Even a pro- 

 gram of physical conditioning over 

 several months can alter an individual's 

 Beg to as great an extent as the differ- 

 ences seen among species (Elsbach 

 et al., 1970, Holloszy et al.. 1964). 



The major difference among the 

 Bcg"s of various mammals seems to be 

 one of timing of the systolic wave 

 forms. As body size increases, the on- 

 set of the systolic complex is delayed 

 (QH interval) and the complex spreads 

 out (HJ and HI. intervals. Table 1). 

 If we consider the tip of the H wave 

 as the onset of ejection, we shall at 

 worst slightly underestimate ihe 

 cardiac pre-ejection period. Certainly 

 the relative values among species can 

 be estimated by the QH interval. Sim- 

 ilarly, ejection time can be estimated 

 by the HL interval. This interval did 

 not seem to be so relatively prolonged 

 in Gigi as the QH. The contribution 

 of prolonged conduction time in 

 hearts of different sizes to the inter- 

 species differences in systolic time 

 intervals is probabK considerable, as 

 is shown b\ the PR and QRS intervals 

 in Table 1 . 



In general, heart rate and ejection 

 time are inversely related. Thus part 

 of the differences in systolic time 

 intervals is due to heart rate differ- 

 ences. But heart rate cannot explain 

 all of the differences. Gigi's heart 

 rate of 43 beats/min was not as slow 

 as expected and occurred presumably 

 because she was excited. An athlete 

 with a heart rate of 40-45 beats/min 

 does not show the prolonged pre- 



Table 1. — Some comparative values among mouse, man, and whale. 



Weight (gm) 

 Length (cm) 

 Heart/body mass 



(gm/100 gm) 

 Heart rate (beats/mm) 

 Beg IJ amplitude 



(cm/sec-) 

 Beg IJ amplitude 



(corrected, cm/sec^) 

 Bog IJ amplitude 



(dynes) 

 Cardiac output (l/min) 

 Cardiac index 



(Ml/mm/kg) 

 Stroke volume (ml) 

 Stroke index (ml/kg) 

 PR interval (msec) 

 QRS interval (msec) 

 QH interval (msec) 



"Pre-eiection period" 

 HJ interval (msec) 

 HL interval (msec) 



"Election time" 



-t- With tail 



 Corrected for mass of bed IJ 



= Measured in Gigi 



I Walker, et al , 1968 



- Altman and Dittmer, 1971, p. 240, 



' Altman and Dittmer, 1971, p. 236-7 



^ Altman and Dittmer, 1971, p. 239. 



/Tota!Mass\ :! '^"-"''^-" ^"t°""^^^' ^^^^' " 3"° 



I p„^, ..,,, I '■ Juznic. 1970 



VBody Massy . Starr and Noordergraaf, 1967. 



« IVloss. 1961 

 9 Cullen, et al . 1970. 

 I" Altman and Dittmer, 1971, p. 323- 

 " Altman and Dittmer, 1971, p. 278. 



ECG 



n 4- 1 1 1 1- 1— 



ULF BCGa '-wU ^"^-^-ni| Vjw. 



',yv-%AA^,^, 



PG 



Timo. In seconds 



Figure 6a. — These (wo tracings are from a conscious dog after cardiac autotransplantation. The 

 Beg is essentially normal. PG = Pneumogram (Whitney gauge). 



ECG-n 



ULF BCGa 



-!^^-- 



^-A-.v^->V' 



PG 



Time in seconds 



Figure 6b. — These tracings are from a dog in the terminal stages ol rejection after cardiac allo- 

 transplantation. The difference between the ballistocardiographic records from the two dogs is 

 obviously greater than that between Ihe tracings from a whale and mouse (Figure 5). 



13 



