1102 
MONITORING 
47.000 readl: call opeii(EKGin) ; call open(p — in); 
48.000 read2: call read(EKGin,a) ; call read(p— in,b) ; 
49.000 counter = counter + 1; 
50.000 if counter = 1 then go to read2; 
50.900 /* look for a stimulus output read back in */ 
51.000 do q = 1 to 250; 
52.000 rtime = rtime + 2; 
53.000 if bflag=l & b(q) >threshold then bflag = 0; 
54.000 btest: if b(q) <threshold & bflag=0 then do; 
55.000 if i>l then do; bflag = 1; nstim = nstim + 1; go to rtest; end; 
56.000 outbuf(2) = rtime; ncnt = 50; i = 50; i = 2; nstim = 1; bflag = 1; 
57.000 end; 
58.000 /* now look for the R-wave */ 
59.000 rtest: if a (q) <threshold & rtime>blank then do; 
60.000 rent = rent + 1; if rcnt>ncnt then call hit; 
61.000 if i>l then do; outbuf(l+2) = rtime; i = i + 1; end; 
62.000 else outbuf(3) = rtime; 
62.500 rtime = 0; 
63.000 end; 
64.000 output :if i>22 then do; 
65.000 outbuf(l) = nstim; 
66.000 call initial; 
67.000 put image ( (outbuf(j) do j = 1 to 20) ) (iml) ; 
68.000 iml:'- ._. 
68.500 call drawnew; 
69.000 get data (okay) ; 
70.000 if okay then do; open file(fn) title (name) output; 
71.000 write file(fn) from(outbuf ) ; 
72.000 close file (fn) ; 
73.000 end; 
74.000 step = step + nstep ; z = z + 1 ; 
75.000 if z>nburst then do; 
76.000 ns = ns -|-nsstep; z = 0; step = 0; pause; end; 
77.000 go to readl; 
78.000 end; 
79.000 end; 
80.000 if counter>60 then go to read2; 
81.000 call close(EKGin) ; call close(p — in); put list(counter) ; 
82.000 counter = 0; 
83.000 call open(EKGin); call open(p — in); go to begin; 
84.000 endVAG— STIM; 
DISCUSSION 
P. G. Katona, Case Western Reserve Univer- 
sity, Cleveland: I w^onder if you'd elaborate on 
your statement that this might be useful for 
driving the natural heart from an artificial 
heart? I was wondering why you found it useful 
to do it that way rather than driving the arti- 
ficial heart from the natural heart. 
Dr. Dong : I didn't make any comment on the 
usefulness of it. I'm just commenting on the 
fact that it is possible for that to occur. If 
you're taking an assist device and not synchro- 
nizing it to the natural heart and you think you 
have two pulse generators working independ- 
ently, under certain conditions, it is possible 
to force the natural heart to beat to the driving, 
artificial heart without any electrical or physical 
connection. It's possible that you'll drive it 
through the baroreceptor and through the cen- 
tral nervous system. I remember, and I haven't 
been able to identify it (perhaps somebody in 
the audience can), an observation made by the 
Houston group in which they did such a thing. 
They permitted the artificial heart to beat in- 
dependently of the natural heart, and they made 
an observation that at around 60 beats a minute 
the two hearts (one artificial and one normal) 
would synchronize. 
