Ondersiepom·t Journal of T'r-terinlli)J Science and Animal industry, Folume 14, .\"umuers l and 2, .lonum·.11 onrl Aptil, HJ-+0.
]'rint{'d in tht· Cnion of South Africa b_,. the Go,·ernnwnt Printe:·, Pretoria.
Anatomical Studies No. 63: An Abnormal Bovine Heart.
Hy .J. H. L. UL(H;TE and H. P. S'l'EYK, Sections of Arwium." and
~urgery, Onderstepoori.
'l'nE major.it,y of lhe reeonled abuonualilies of the heart U::ieh\\·albe, 1909) art> of n•htiYel~- .-;inrplt> mdurP, e.g. p:1tt>ni forarneu oYale and ]of·nlise<l ,.;epi-al defects. Tbt! lath·r are u,;ually limih•cl to the ahial st>ptulll, oc-cmTiug- mtwh h•,..;s hequently in that of the l'f'ntrides. Their fret1uenc·y is greatPr in tht• more basal parts th<tn towards the apt>x (Bailey antl )Iillt>r, 1927). )fuch morn rarP are anomalies afteding- both atria and Yeni riclt>s, "·hilt) a sean·h of the literature reveals but a fe\Y records of (:a,;es in whil'h, in adclition to hoih spt,; of ('h:mr1wrs. the lliHin arierial stems \I'PI'P :ilso inl'ohed.
S11bject.
Th(· ltearL i,; ih;~t of :1 n~:ile (';!If found' clea<1 iu the ndl1 ou the morm11g- of 21-12-=~u, :lpparently a fc•11· hom·s subsequent to birth.
The f·alf was hy an Afribucler hull (D.O.B. -1-Rl9) out of a hig-hg-r:Hle Su;;st>x c·ow (D.O.B. :)420). The' foeius had heen <·anied for :2D(i
1la~·s. nnc1 at birth it 1·omparPcl hlYOllrahly, as n•g-ards hoth \\'Pig-ht
u::
lh.) f1Jl(1 1leg-ree of deYelopnwni. ,,·ith other l'ahes similarly bred under iflentieal eJrvironmNtbl I'OnclitioJJf'. OthPr tlwn the- l'ardia(' ahum·mnlit,\· io hp desl'rihed :mel seYeral skin abrasion,;, tlw auiops_1·findings ,,-pn• entirely neg-nhn·. H ,,.;1,.; (1e('if1ecl thni the 1·nlf had hPf'n horn nli1·p anc1 that it hac1 hreathed.
nesr·riJII'ioll of the Heart (///(/ T"essels.
rn thi;; clescripi.ion tlJP heari j,; looked upon a,..; ht>ing· in si/11
anc1 tlw animal in th1· nonnal standing- posture: tlrus tlw 11:1se of the he<trt is dor~al, thP :1pex venh·nl. rlw rig·ht atri111U anc1 ,·pntrif·IP nanial nnd ihe }pft chambers ca11flal.
(o) External Appearance.-A,; 11ill hP ,;t'Pll front Fig. I. Hw shape of the ht>ari cliffprs from the normal in that it is ~horiened in the <lorso-Yentrnl cliredion: 11·ider and more roun!ll'cl at i hP a pPx.
1 By H. P. S .. 1rho 1n1s at that time Officer in Charge nf the \'pt(•rin:n·~·
Ht>srareh Station at Arn1oed~''lnkte. near \"ryhurg. C'.P.
AXATO.\IIC.-\.L STuDY SO. (j:J.
Further it is distinctly flattened from side to side. The usual longitudinal grooves are absent, but there is a faint horizontal o-roovP midway down the posterior surface of the ventricular portion. \bove this groove a backward protrusion of the ventricular myocarrl break:>
the usual straight line of the caudal border.
The left atrium is attached to the right atrium only, there being no connection between it and the ventricular portion of the heart.
482
,J. Il. L. CLOETE A :-;o H. P. STEY~.
At the base of the lwart the u~ual aortic a1Hl pulmonary truub are replacecl b~- a single large cone-shaped YessPl, dearly viRible from the left side (Fig. I). This nssel l'xtenrl~ up\\·ards for a distanCL' of two inches befon~ it diYides (see Fig. 2) :1~ folln"":-
Art.
Brdnch Aortd
- -Lefl Pulmondry Arf.
CoronCJry Arlery
Lefl Arrium
(i) .·1orta.- This. thP laq..(·Pst branch. npjw:ns to lw the din"ct
!'Ontinuation of lhl' m:1in trunk. It cun·h; up\\·anl and back- ,,·:ucl to real'h tlH• dorsal ,,·all of tlw thorar·i(' r·a,·ity.
(ii) Co111m011 Brol'!tior·ephalu· Trunl.·.- 'l'his is .~e•·oJHl in point of size. 1 t arises directly opposite t hr forrg·oing YPSsf'l aud it passes fon1·anl to\\·arrls the entranr·p to th!' thoracic !'aYil~·.
(iii) cl Fairly Lm·.r;e l'cs.<el arising- at thP santP lt··n·l as the ahon·
and to the right of it. This probably rP])I'Pst'nts one of the hrancht•;; of the bra!'hiocephalir: trunk. llnwev\'r, in the illustration it i;; Jnarb·d n~ a branr·h of thf:' aorta.
(iv) The Nir1ht Pulmonary A rlvry.--This originat0s at the lett cranial asped of the main trunk. It is of the same ca lihrP a;:. (iii) b,tt at its hnse thrre is a marked con.-dridion.
(v) The Left Pulmonary Artery.-Emanating from the base aorta, tmntrrl~ the c:andal aspect, and }laYing nn constrietion similar to that of the right artery.
of t lw in i tia 1
A.t a rli~tnncc of one inc:h from the point of orig-in of the riglli pulmonary artery there arist>,.; a small v<•ssel which, lying- upon tlw left face of the maiu arterial trunk, runs diredly toward.~ the bnse
A:K,\TOMICAL STCDY ]1;0. 63.
of the heart where it splits into two branches. These, coursmg 111 opposite directions a long the coronary grooves, appear to be the eoronar:y arteries. K o further eoronary blood i:iUpply is detectable.
As is to be expected, neither the ductus arteriosus nor the l igalllentum arteriosnm is present. The n·na envae and the pulmonary veins orwn ns u.-ual into the right and the left atria respPctively.
Atria· ventricuiM vdlves
Semi -lunclr vc~lve~
Fordmen .nto l.ventricl e
Incomplete dividlnq septum- R.venrncle.
F.ig. 3.- J ntern:t I n ppeara nee, kft lateral view.
(/J) Internal Appearanee.~The left atrium ha~ uu veutri<·ular conununication; however. a patent foramen ovale is encountere<l. 1 n the right atrium there are nu unusual features. As seen in Fig. 0 the right ventTide eompTi;;es almo;:;t the entire wntricular part of the organ. By a slight longitudinal elevation of its right myocardial wall the cha.mbeT is incompletely di\·ided into cranial and caudal compartments. 'l'he right atrium opens into the former, \\·hile thE' latter extencls ventrally into the apt'x and doTsall,v into thP main arteTial trunk, from \Yhich it is <lemarcated by a three-cuspid semi-
lnnar Yah·e. Just ventral to the posterior of these cusps a forame11, about one inch in <liamPter, opens through the myocardial wall into the w,.;tigial left n nhide. The latter is containerl in the posterior p1·oh1I,;ion visiblP extt>rually. His found to consist of a simple holJO\\' r·hnmLt•r with hul onl~ opening~that into tlw rigM Yentriele. The muscular 'ndl is complete and the eavit:v i" liw:-11 by enrloeardium
<'OHtimt01IS with that of the larger Yentricle. Temtolom;.
The, mammuli:w heart develops from a single tube, along the ('01ll'Se of w·hicl1 thrt>P enlargemPnts appear. In turn these are divided, through the appearance of septa, into paired atria, ventricles and arterial trunks--aortic and pulmonary. 1n the ease nuder con- sideration this process has been disturbed, resulting in misplaced
484
J. H. L. CLOETb X~D H. P. STEY~.
diYision of the Yentricles (with consequent atrial anomalies) antl total failure of division of the bulbus. The latter remains as ::t common ::trterial ~tem, in the sub-diYision of 11·hich all the main l>mnches of hotb the :oorta and the pulmonary artery are representerl.
Foetal Circulation.
Jn this case a single functiorwl YeutridP and a t:onunon arterial stem maintained the entire t•irculaiiuu, pulmonary as \Yell as systemit·.
'!.'he fonner heing· rdatiYe]y unimport;111t in the ftwtus, constrictions at the bases of the pulmonary arteries ,;en ed to keep the bulk of the blood-Yolume in the ~ystemic Yessels. For the small ....-olume of blood returning hom the lungs to the left atrium there was hut one uutlet, namely, into the right atrium, thus reYcrsing the usual rlirection of flo''" through the foramen OY~de.
The ,;iguificnut·t• of this t·n.-;t> e:\teuds far he_\-OIHl its teratologicu I 1·arity- it forms nn important c-ontribution to the literature on the foetal r·i n·u lation.
H is kno,,·n that i11to the right atrium nre poureci t1nJ strenll!s of l1lood of rlitteri.ng- q twlity, 11a mely, the o.xygen-po01 blood from tl1e ~;rani:tl ,.PrW cant <liHl the reht1iYely pme hl~)()d from the cauclnl vPna <"<l"<t. The traditional lwli<•f, hnserl on the teaching of Sabatier (1791). has been thnt b,,-certain <IIWtoJniC"al ;nTa ng-em.ents 11·ithin the 1ig-ht atrium, tl1ese- hYo streams are kept apart, ftnrl thnt suhsequent-ly tht" pm·est. hloocl is rli:-;hilmted t.o the hrat"hin-r:ephalic <"irculation. This purely hn)(Jtheiir-nl conception i,; hased upon the supposecl :l(lvantag-es thn1 ,,·oulrl acrTue from a ~eg:regation of pure and impure blo()(l. S:1vt> for the npparPut hig·hly Ullsatisfador:;· ,,·o1k of Heirl (18;16) there "·as, until n•r·t>ntl~-, no attempt at e:\perimeutal Yel ifi- t:ation of the 1lwory. X PH'J-tlwle~,; thi:-; t•l:lssir:a l expl:lllatirm lw~
t•nj0~-<··d immeDc;P popularity nnd it· is to he found, fait·hfnll_1· repm-
dnr:t-d, not only iu the ol<ler text", but also in works of nnu·h mort>
recent origin (e.g. ~eitschmam1, 1924; Bailey & )filler, HJ27); and this rll'spite the fact that ahead.v in 1907 Poh lmanu had l'eYiYerl Harvey's (1628) theory of romplete arhuixture of the two streams, and had (1901-9) furnished experimental cnrrohorat.imt \Yhieh, ulthough perhaps somewhat inconelusiYe, we11t far towards clis- t;rediting the Sahatier tt>aching. Extending- this inYe;;tig-ation, Kellogg· (1929) sholl·t··rl that immediately after injec-tion into either the jugular, the anterior or the nosterior ....-ena caYal Yeins, of Rtnreh solutions or india ink, these suhRtances "·ere recovered in appro:\i- matel_v equal concentrationR from the two Yentricles. But for the possible criticism that b.v- artificial interference the natural mer·ha11ism i~ liable tn be disturbed, these resultR would prove r·on-
clu~ively tl~;d in tht> right atrium there is definite mixing of the bloodstreams. Ho11·r;wr. Kellogg· believes that ull the points of rJ·itif'ism may he refuted. In a later study (1930) in which seusitiYe g·aseous ana lys(~S of blood samples drawn simnlt:meously from various region,; of the foetal system are the rriteria, he rerords results which nndir·att> his earlit>r conclnsions.
_\~ATOJ\UCAL· STliD~ l\0. ()3_
However, in spite of their acceptance by Arey (193-:1:), who, judging from Kellogg's acknowledgement, appears to have been in a position to appreciate their merit, these findings have not resulted m a settlement of the controversy. Barcroft (1936) points out that in all Kellogg's (1930) results the figures for oxygen content are extremely low. Like Huggett (1927), he finds that in the small ruminant foetus the percentage oxygen saturation \-aries in uecreasing sequence in samples of blood drawn from the posterior vena cava, the carotid and the umbilical artery. Statistical analysis of Barcroft's data shows that the difference between groups two and three (carotid and umbilical artery) is just significant at the five per cent. level of probability, whereas bet"-een numbers one and three (posterior vena cava and umbiliral artery) there is a differen('e highly significant even at P =O·Ol. Thus, as far as these results are concerned, Barcroft is justified in concluding that " there is on the whole a differenee ·' bet"-een ~amples of · blood hom the an te1·ior and th t'
posterior systemic arteries. However, in view of the fact that thP t.wo significant differences just mentioned are of widely varying onler, we <·onsider the qualification, " there is eYidPn<·<~ of some m·oc;c;ing- of the two streams ". to he of equal impm tanee.
~ioreover, it must he bon1e in mind that iu the eolleetion of tbese blood sampleH thb foetuse~> were probably nll held in the SfUU<-o
fixt>cl posihon; thi;; po;;ition may have been favourable to an increased tiow of blood throng·h thl:' forammt OY;de. From an;~tomical <:onHidP- mtions it is not diffi,·nlt. to <:onePiYn of such po~itions; on the otlwr hand it is equally easy to pidure po~itions 11-hi.f'h might pre-
di"JlO~<-' towarrl" thoroup;h mix[ng· of til<~ shPam;; 11·ithin t-lw 1·ip:h1.
at ri lllll.
The fnrther lUll"' hcl\\-eYer l'e:;ervedl;y' of the..;t• hig-hly \·aria ole datu for the purpose of apportioning the extent of nossiug of tlw streams is questionahle. Here exception is taken JJot so mur.h to the possible inaccnrac:v of the re,;ult as to the implicatio11 that there ii-i iu exiRtence a llte<·hanis111 through which only <1 limil<•<l aJICI
d~~finitP-ly <leLerminahle auwtttd of mixing of thP 111-o 1->hf'<lHJS if<
allowed: ag·ain the hasi;; of this idPa is the supposedly prcft>rPntinl treatmPnt·. in the matter of oxygen :-;npply, of the more <Tanial part of the foetal ho<h. The lilllit to 1rhich thi::; theory 1ua\· he strPtr:hPd is ,,-ell indica te<l. in Ba mm·d ',.; (1 ~)08) discussion ~lf a
o
aneurism of tlw left l'f'lltricle, thP rPsult of the left l'orouary artPr.r takit1g origin from the pnlmon<u~· <lrter,v. He m:tintaius that the pt·ocp,~shad ahea<ly been in;;{ igated in the foetal pet·iod by the dt>pri,·;ttion of thif< part of thP ntyocanl of" jl1tre hlo(}(l " fro111 ihe aodn.
The PntirP theory i,.; bnsed maiuh ott the• obserYed n'lati1eh· larg-e size· of tlte foetal hencl. lbghtl.r KPllogg- (1928) has pointPcl ou't that t]w clomill<llll't' of thiR region is Jiutitefl to t]w ParliPI' pad of prPnntal life. and that latPr the ahcloll!in,d :n11l pehit· rPg-ions unclergo l':lpid g·mwth rutrl differentiation. Statistically it has hPen f<ho\\·n hy onp of 11S2 tJ,at in reg-io11~ ~lll'h aR the limbs, from Pnrly i11
' J. H. L. C. in ann~ Yei. llll[lllhlis!Jptl 'tnd\·
or
fo<'t.al gl'(ndh and clPI'elop- lllent in the ~[eri 110 ~llePp.'486
J. H. L. CLOETE A:\"D H. P. STEYN.
prenatal life, the true grmYth-rate of the (·audal wember is alway~
higher than i bat of the eranial one. How eYer. in the ln tter the .inception of gnmth OC<'urs earlier (chronologicallY) and hence this member obtain,; a " start .. \Vhieh ensures that for a long tin1e it will be rela ti \·ely larger than the faster growing eaudal mew her. OH this basis the reason for the disproportionate size of the foetal head is its early entry into the g-rowth process; heru·e the fallacy of hypotheses based upon the supposed· aeeelerated growth, ancl consequent increased Hxygnn I'l'([Uirements. of thP braC'hioeephalie reg-iou.
For these reasons we indine towards a modified Harvey-l'ohl- mann theory which. while admitting the absence of constant, thorough and complete mixing of the two caval streams, regards any difference in the quality of blood in the uppPr and the lower systemic arteries as " acci(lental " and physiologiC'ally meaningless.
Su<.:h a modifi<.:ation seems to have been implied by Kellogg, for his contention, after a considt'rahlc and varied number of tests, is not that the blood in the hvo ventricles is always identical (his results prove otherwise), but that snch <lifferences as do appear nre incon-
;;;tnnt, variahlr <~tttl of 110 momenL
" 'L'o thotle \l·ho obtain men tal satisfaci ion hom fitting
supposedly advantageous me<·hanisms to physiological ideals, the Harvey-l'ohlmann theory may be disappointing. Yet it is by no means eerbin that there is any ne<~essit.y in maintaining- a difference i11 the <rua lity of blood distribni ed to Yarious pa rb of t hf' booy.
(;jl"("Ulatory effieiellCJ' in the llHilUtnaJiull Plllhryo douht}E'<'S depend;, jointly on the relati\·ely large quantity of s,,·iftly nto,·ing- blood, aud on the large faetor of safety in the oxygen supply." In these word;;
Kellog-g appear~ to lay upon those who still persist with th<• Saba tier ,·ouceptiou the ouu,- of dPfinite proof of the necessit:-· for separation. HoweYer, i11 addition to facts alread~· a(hancell. the <·a~<' reeonlPd in this article iR a n<ltural experiment which hns provecl rffechvely that such sep:rq:ration is not an essential f<tctor in foetal g-rowth ancl devclopnwnt. 'J'hnc; thr babm·r hns he<'n wPig-htrd against Hw rlis(·barg-P of this onu~.
REFERI<:NCE~ .
• ·\HEY. L. B. (193,l). 71err•/opmentul !lnafm"''· :Jnl l•:dit. \Y. H. Sannclers Com·
pany. Philaclelphi:1 nncl London.
BAILEY. H.. B .. . \:-<1> }II LT:I~lL .\. :.\[. (19211. 1'r'.ff-/,1Jol; of Kmllryoloqy, 4th Edit. \Villia1ns \\'ood und Company. ?\e11· York.
BAllCROE'T. J. (1936). L'dnl circulntion and respiration. l'hysio/ ](,., .. , Vol.
16. No. l. pp 11J3-l28.
IL\RKARD, \\'. G. (l93S). Aneurism of tl1e left ,·entri("]e clue to rh<· left
coronar~· artery taking origin from the pnlnwnnry nrtf>ry . .f. l'11tl1. and l:Jact., \-ol. 47, 1\o. '2. pp. 3J.)-:J46.
I'L\RVF:Y, W. (1628). Cit. Kellogg (Hl2R).
I:JUGGE'l'T, A. ST. C. (1!?21). Foetal blood-gas tensions and gas transfusiol•
through the pl:wcnta of the goat. J. l'hy.,iol .. Vol. 62, So. 4, pp. 373- 384
A~ATO)J !"CAL STCDY SO. t):t
KELLOGG. H. B. (1928). Tlw Pour~e of the blood flo11· through the fdal mammalian heart. dm . . J. Anat., Vol. 42, No. 2, pp. 443-465.
KELLOGG, H. D. (1930). Stud ics on the fetal circulation of ma mmu Is. Am. J. l'hysiol., Vol. 41, Xo. 2. pp. 637-64.8.
POHL:\lA:\X, .-\. G. (1907-'J). Cit. KPllogg (HJ28i.
REID, J. (1830). Cit. Ibid.
SCHIY.-\.LBE (1909). Die Jiorpholoaie der Jlissuildunaen des Jienschcn tmd II,., 1'ierr. TPil 3. Gusbv Fi~C'lwr, Jena.
SISSON, S. (1927).1'/lc .-lnatomy of the Domestic Animols, 2nd Edit. \Y. B.
RnunclPrs Compan~·, l'hilnclelphin nncl London.
ZEITSCH:\1.-\~:\. 0. (1924). J,ehrbuch der Ent-wir/,lungsgl'srhirhte der Jlnus- tirrr. Ri<.:lwrd Schoeh. Berli1~.
488
