1. VTT 235/245 Ana tomy &
P a thology La b for Ve te rina ry
Te chnicia ns
Ca rdiova s cula r S ys te m
I. Ca rdia c S ys te m
II. Circula tory S ys te m

2. Ca rdia c S ys te m
The ma jor function of the CVS is
tra ns porta tion, with blood be ing the
tra ns port ve hicle .
Circula tory P a ths -
Systemic Circulation- is blood flow to a nd
from mos t pa rts of the body.
Pulmonary Circulation- is blood flow to
a nd from the lungs , during which it picks
up oxyge n a nd re turns it to the he a rt.

3. Ca rdia c S ys te m
Circula tory P a ths -
Coronary Circulation- blood flow to the he a rt
mus cle its e lf.
Portal Circulation- a ve nous s ys te m in which
blood re turns from the inte s tine s a nd proce e ds to
the live r be fore re turning to the he a rt.
* * Venous System- re turns blood to the he a rt.
Arterial System- ca rrie s blood a wa y from the
he a rt.

5. He a rt
A mus cula r, four cha mbe re d orga n tha t
drive s the circula tory s ys te m.
Lie s in the mediastinum.
Base- top of the he a rt.
Apex- bottom of the he a rt.

6. He a rt…
The oute r la ye r of the he a rt is ca lle d the
pericardium.
The pe rica rdium cons is ts of 2 la ye rs :
An oute r fibrous pericardium- ma de of tough,
fibrous CT tha t prote cts the he a rt a nd loos e ly
a tta che s it to the dia phra gm.
An inne r serous pericardium- which is a ls o ma de
of 2 la ye rs :
Inner Visceral layer(epicardium)
Outer parietal layer

7. He a rt…
Ins ide the s a c forme d by the
pe rica rdium is the thicke s t la ye r of
he a rt tis s ue , the myocardium.
Be twe e n the cha mbe rs a nd the
myoca rdium is a thin me mbra nous
lining ca lle d the endocardium.

8. He a rt…
Compartments- the he a rt ha s 4 cha mbe rs .
The 2 a tria re ce ive blood a nd pump it down into
the re s pe ctive ve ntricle s , which pump it a wa y
from the he a rt.
Right Atrium- compa rtme nt re ce iving
de oxyge na te d blood.
Interatrial septum- the wa ll s e pa ra ting the a tria .
Fossa Ovale- a re mna nt of the fe ta l fora me n
ova le .

9. He a rt…
Right Ventricle- compa rtme nt
re ce iving blood from the right a trium.
The right ve ntricula r wa ll is thinne r
be ca us e le s s pre s s ure is re quire d to
move blood through the lungs tha n
through the body.
Ventricular septum- s e pa ra te s the
ve ntricle s .

10. He a rt…
Left Atrium- the compa rtme nt
re ce iving oxyge na te d blood from the
lungs via the pulmona ry ve ins .
Left Ventricle- compa rtme nt re ce iving
oxyge na te d blood from the le ft a trium
a nd s e nding it out the a orta to the body
(s ys te mic circula tion).
The le ft ve ntricula r wa ll is thicke r be ca us e
of the highe r pre s s ure re quire d for
s ys te mic circula tion.

11. He a rt…
Ve ntricula r S tructure s -
Papillary Muscles- mus cula r proje ctions
s e rving a s a tta chme nts for the chorda e
te ndine a e of the AV va lve s .
Chordae Tendineae- tough s tra nds
a nchoring the fre e e dge s of the AV va lve s
to the pa pilla ry mus cle s .

12. He a rt…
Va lve s -
AV Va lve s - pre ve nt ba ckflow into the a tria
during ve ntricula r (s ys tole ) contra ctions .
Right AV (tricus pid) va lve
Le ft AV (bicus pid/mitra l) va lve
“Tri” before you “bi” !!!
S e mi-luna r va lve s -
Aortic
P ulmona ry

13. Ma jor Ve s s e ls
Cranial Vena Cava- the la rge ve in
re turning blood from the he a d, ne ck,
a nd thora cic limbs to the right a trium.
Caudal Vena Cava- la rge ve in re turning
blood from pa rt of the thora x, vis ce ra ,
a nd the ca uda l pa rt of the body to the
right a trium.

14. Ma jor Ve s s e ls …
Pulmonary Trunk- the la rge ve s s e l
ca rrying blood from the right ve ntricle
to the pulmona ry a rte rie s , a nd thus , to
the lungs .
Pulmonary Arteries- the two bra nche s
of the pulmona ry trunk ca rrying blood
to the right a nd le ft lung lobe s .

15. Ma jor Ve s s e ls …
Pulmonary Veins- the nume rous
ve s s e ls e mptying oxyge na te d blood
into the le ft a trium.
Aorta- ma jor outflow from the le ft
ve ntricle into the s ys te mic circula tion.

16. Ca rdia c Cycle
Both a tria contra ct a t virtua lly the
s a me time .
Blood e nte rs the a tria while the y a re
re la xe d.
The atrioventricular (AV) valves a re
ope n s o blood flows ra pidly through the
ve ntricle s .
Approxima te ly 70% of ve ntricle filling
occurs during this pha s e .

17. Ca rdia c Cycle …
The a tria the n contra ct, which is ca lle d
a tria l s ys tole , a nd the ve ntricle s fill
comple te ly.
Ne xt, both ve ntricle s contra ct a nd the
AV va lve s a re force d to clos e ,
producing the firs t a udible he a rt s ound.
P re s s ure on the ve ntricle s ca us e the
s e mi-luna r va lve s to ope n a nd blood is
e je cte d into the pulmona ry a rte ry a nd
a orta .

18. Ca rdia c Cycle …
This contra ction is ca lle d ventricular
systole.
The s e mi-luna r va lve s clos e producing
the s e cond he a rt s ound.
The cycle is re pe a te d with the pe riod
of re la xa tion ca lle d diastole.

19. How Blood P umps Through the
He a rt
 The Right Atrium, re ce ive s “de oxyge na te d blood" from the body.
Blood will be pus he d through the tricus pid va lve to the
 Right Ve ntricle , the cha mbe r which will pump to the lungs through the
pulmonic va lve to the
 P ulmona ry Arte rie s , providing blood to both lungs . Blood is circula te d
through the lungs whe re ca rbon dioxide is re move d a nd oxyge n
a dde d. It re turns through the
 P ulmona ry Ve ins , which e mpty into the
 Le ft Atrium, (oxyge na te d blood) a cha mbe r which will pus h the Mitra l
Va lve ope n. Blood the n pa s s e s into the
 Le ft Ve ntricle . Although it doe s n't a lwa ys look like it in dra wings done
from this a ngle , this is the la rge s t a nd mos t importa nt cha mbe r in the
he a rt. It pumps to the re s t of the body. As it pumps , the pre s s ure will
clos e the mitra l va lve a nd ope n the a ortic va lve , with blood pa s s ing
through to the
 Aorta , whe re it will be de live re d to the re s t of the body.

20. He a rt Ra te & Ca rdia c Output
Cardiac output- the a mount of blood
tha t le a ve s the he a rt.
De te rmine d by:
Stroke Volume- the a mount of blood
e je cte d with e a ch ca rdia c contra ction.
Heart Rate- how ofte n the he a rt
contra cts .

21. Conduction S ys te m
Ea ch comple te contra ction a nd
re la xa tion is ca lle d a cardiac cycle.
Two ma in pa rts -
Systole- whe n the he a rt mus cle contra cts
a nd blood is e je cte d from the a tria to the
ve ntricle s a nd out the a orta .
Diastole- the he a rt re la xe s a nd re fills with
blood.

22. Conduction S ys te m…
The impuls e come s
from the SA node.
A s pe cia lize d a re a
of ca rdia c mus cle
ce lls tha t pos s e s the
a bility of
a utoma tica lly
ge ne ra ting the
e le ctrica l impuls e s
tha t trigge r the
re pe a te d be a ting of
the he a rt.

23. Conduction S ys te m…
The S A node
ge ne ra te s a n
e le ctrica l curre nt by
the move me nt of
ca tions a cros s the
oute r me mbra ne s of
it’s ce lls .

24. Conduction S ys te m…
This proce s s ca lle d depolarization,
ge ne ra te s a n e le ctrica l curre nt which ca us e s
the he a rt mus cle to contra ct.
Ca rdia c mus cle ca n tra ns mit a n impuls e
from one ce ll to a nothe r, s o e le ctrica l
impuls e s a nd contra ctions s pre a d a cros s the
he a rt like a wa ve .
Afte r the impuls e is ge ne ra te d in the S A
node , it s pre a ds in a wa ve a cros s both a tria ,
ca us ing the to contra ct a nd pus h blood
through the AV va lve s into the ve ntricle s ,
which a re s till re la xe d.

25. Conduction S ys te m…
The impuls e tra ve ls to the AV node whe re it
e ncounte rs a s light de la y.
This is the only conduction route from the a tria to
the ve ntricle s .
The de la y pe rmits the a tria to comple te the ir
s ys tolic contra ction be fore ve ntricula r s ys tole
be gins .
Afte r the AV node , it tra ve ls to the
s pe cia lize d fibe rs in the ve ntricle s ca lle d the
bundle of His & the Purkinje fibers.

27. P a thology

28. He a rt Fa ilure
Whe n blood re turning to the he a rt ca nnot be
pumpe d out a t a ra te ma tching the body’s
ne e ds .
Ma ny ca us e s e xis t.
Mus t de te rmine if the fa ilure is a re s ult of
myoca rdia l dys function (pump fa ilure ) or
circula tory fa ilure (la ck of circula ting fluid
volume .
Conge s tive He a rt Fa ilure - whe n the fa iling
he a rt a llows fluid conge s tion a nd e de ma to
a ccumula te in the body.

29. Congestive Heart Failure
A de ge ne ra tive dis e a s e whe re the va lve
le a fle ts be come knobby a nd thicke ne d.
Re gurgita ting blood ca us e s e nla rge me nt of
the le ft a trium a nd le ft ve ntricle
Mitra l re gurgita tion mos t common ca us e ;
30% of s ma ll bre e d dogs > 10 ye a rs old a re
a ffe cte d
P re dis pos e d bre e ds include Ca va lie r King
Cha rle s S pa nie ls , P oodle s , Mini S chna uze rs ,
Chihua hua s , Cocke r S pa nie ls , Da chs hunds ,
Bos ton Te rrie rs , & Fox Te rrie rs
P rogre s s ion of the dis e a s e ca n ta ke ye a rs

30. CHF (cont)
P re s e nt with ta chypne a , ha rs h lung
s ounds , ins pira tory cra ckle s tha t
progre s s to cra ckle s /whe e ze s
throughout re s pira tion with a
dis tinguis ha ble he a rt murmur
CHF a nima ls a re lite ra lly drowning in
the ir own fluids .

31. P a te nt Ductus Arte rios is (P DA)-
 Mos t common
conge nita l he a rt de fe ct
of dogs
 The duct be twe e n the
le ft pulmona ry a rte ry
a nd the de s ce nding
a orta in the fe tus doe s
not clos e a t birth
 Re s ults in le ft s ide d
CHF
 The re s ulting murmur is
ofte n re fe rre d to a s a
“ma chine ry murmur”.

32. Va lvula r S te nos is
A na rrowing of one
of the he a rt va lve s
Ma y be a ortic or
pulmonic
Ca us e s va rious
type s of murme rs

33. P e rs is te nt Right Aortic Arch
P RAA
The mos t common
va s cula r ring
a noma ly
Ca us e s a n
obs truction of the
e s opha gus
Re gurgita tion, a nd
a s pira tion
pne umonia a re
s ome s igns in young
we a ning a nima ls

34. P a te nt Ova le Fora me n
A.K.A. Inte ra tria l
S e pta l De fe ct
Fa ilure of the
ope ning be twe e n
the two fe ta l a tria to
clos e .

35. Chronic Mitra l Va lve Ins ufficie ncy
CMVI is the mos t commonly
e ncounte re d a cquire d ca rdia c
dis orde rs in the dog.
One of the mos t common ca us e s is
chronic pe riodonta l dis e a s e .
Ba cte ria living in ta rta r a re s howe re d into
the bloods tre a m, colonizing on the va lve
le a fle ts of the he a rt.
The s tiff, ma lforme d le a fle ts fa il to clos e
s ufficie ntly during s ys tole , re s ulting in
re gurgita tion ba ck up into the a trium.

36. Ca nine Dila te d Ca rdiomyopa thy
One of the mos t common a cquire d
ca rdiova s cula r dis e a s e s of dogs .
P rima rily a dis e a s e of olde r, ma le la rge &
gia nt bre e d dogs .
The dis e a s e involve s the dila tion of a ll four
cha mbe rs of the he a rt.
This dila tion (ca us e d by we a k, thin, & fla bby
ca rdia c mus cle ) re s ults in:
A de cre a s e in ca rdia c output.
An incre a s e in ca rdia c a fte rloa d (blood le ft in the
he a rt in dia s tole ).

37. DCM…
The e xa ct ca us e is unknown, a lthough
vira l, nutritiona l, immune -me dia te d,
a nd ge ne tic ca us e s ha ve be e n
propos e d.
DCM re s ults in impa ire d s ys tolic
function of the ve ntricle s a nd,
the re fore , de cre a s e d s troke volume .
The volume of blood e je cte d from the
he a rt with e a ch contra ction.

38. DCM…
The e ffe ct on the a nima l is one of low-
output circula tory fa ilure , e xhibite d by:
We a kne s s
Exe rcis e intole ra nce
S yncope
S hock

39. DCM…
Dogs with DCM fre que ntly e xpe rie nce
the de ve lopme nt of a tria l fibrilla tion,
which furthe r contribute s to a de cre a s e
in ca rdia c output.
S igns of a tria l fibrilla tion include ra pid,
irre gula r he a rt rhythms or s udde n de a th.

40. Ca nine Hype rtrophic Ca rdiomyopa thy
An uncommon ca nine dis e a s e .
The le ft ve ntricula r mus cle a trophie s
de cre a s ing the filling ca pa city of the
ve ntricle a nd ofte n blocking the outflow
of blood during s ys tole .

41. Fe line Dila te d Ca rdiomyopa thy
Afte r the a s s ocia tion of the dis e a s e
with ta urine de ficie ncy, a dditiona l
ta urine wa s a dde d to comme rcia l die ts
a nd the incide nce of the dis e a s e
s ignifica ntly de cre a s e d.
The pa thologic condition is s imila r to
DCM in dogs .
Evide nce ha s be e n found of a ge ne tic
pre dis pos ition to DCM in ca ts fe d
ta urine -de ficie nt die ts .

42. Fe line Hype rtrophic Ca rdiomyopa thy
The mos t common fe line he a rt dis e a s e .
Cha ra cte rize d by hype rtrophy of the le ft
ve ntricle .
Compromis e of the le ft ve ntricula r cha mbe r
re s ults in impa ire d dia s tolic re la xa tion,
re duction of ve ntricula r filling, a nd ultima te ly
a n impa irme nt in ca rdia c output.
Ca ts with HCM ma y e xpe rie nce he a rt fa ilure ,
a rte ria l e mbolis m, a nd s udde n de a th.

43. Ca nine He a rtworm Dis e a s e
The fe ma le mos quito s e rve s a s a n
inte rme dia te hos t for Dirofila ria immitis .
The s e microfila ria de ve lop in the
mos quito for 2-3 we e ks a nd a re the n
inje cte d into the s kin of a dog through
a bite .
The infe ctive la rva e migra te within the
s kin of the ne w hos t for a bout 100
da ys .

44. Ca nine He a rtworm Dis e a s e …
Young a dults e nte r the va s cula ture
a nd migra te to the he a rt whe re the y
ma ture into a dults .
S ix months a fte r the initia l bite , the
microfila ria ca n be de te cte d in the
blood.
The pre s e nce of the pa ra s ite s re s ults
in right-s ide d he a rt e nla rge me nt a nd
pulmona ry hype rte ns ion.

45. Fe line He a rtworm Dis e a s e
Ca ts a re s ome wha t re s is ta nt to D. immitis
infe ction, ha ving fe w a dult worms , which a re
e limina te d from the hos t within 2 ye a rs .
Mos t s ymptoms in the ca t re la te to the
re s pira tory s ys te m (cough, dys pne a ) or GI
s ys te m (vomiting, a nore xia ).
S udde n de a th of a n a s ymptoma tic ca t is
fa irly fre que nt.
Ata xia , blindne s s , a nd s e izure s ca n a ls o
occur.

46. Murmurs
He a rt murmurs a re a bnorma l s ounds
ca us e d by bloodflow turbule nce .
Due to va lvula r or non-va lvula r proble ms .
S ys tolic murmur- occurs be twe e n the
1 st & 2 nd he a rt s ounds .
Dia s tolic murmur- occurs be twe e n the
2 nd & 1 st he a rt s ounds .

47. Murmurs …
Va lvula r murmurs - a s ound due to a
le a ky or na rrowe d va lve .
Le a ky (ins ufficie ncy) murmur
Na rrowing (s te nos is ) murmur
Non-va lvula r murmurs - us ua lly occur
due to s ome type of a cquire d de fe ct.
P a te nt Ductus Arte rios us
Inte ra tria l or Inte rve ntricula r s e pta l de fe ct

48. Dia gnos tics

49. The Ele ctroca rdiogra m
ECG, EKG

50. Applica tions
Exa ct dia gnos e s of a rrhythmia s he a rd
on a s culta tion.
Acute ons e t of dys pne a
S hock
Fa inting or s e izure s
Monitoring during a nd a fte r s urge ry
All ca rdia c murmurs
Ca rdiome ga ly found on ra diogra phs
Cya nos is

51. Re me mbe r…
DEP OLARIZATION: a he a rt mus cle
contra ction in re s pons e to e le ctrica l
s timuli.
Occurs whe n e le ctrolyte s move a cros s
the ce ll me mbra ne .
S odium-pota s s ium pump
REP OLARIZATION: he a rt mus cle
re la xa tion occurs whe n the e le ctrolyte s
move ba ck a cros s the ce ll me mbra ne
re nde ring the ce ll re a dy for the ne xt
e le ctrica l impuls e .

52. Ele ctroca rdiogra m
A gra phic re cording of e le ctrica l
pote ntia ls produce d by the he a rt
mus cle during diffe re nt pha s e s of the
ca rdia c cycle .
Ea ch portion of the EKG is like a vis ua l
“picture ” of a s pe cific a re a of the he a rt.

54. The Comple x
P wave- corre s ponds to a tria l
de pola riza tion.
Ma y be a pos itive or ne ga tive de fle ction.
QRS Comple x- corre s pond to
ve ntricula r de pola riza tion.
T wa ve - re pre s e nts ve ntricula r
re pola riza tion.
Ma y be pos itive or ne ga tive de fle ctions .
Eve ry QRS comple x MUS T be followe d
by a T wa ve .

56. Le a d S ys te ms
A le a d s ys te m a llows you to look a t the
he a rt from diffe re nt a ngle s .
Lead I- be s t for de te rmining a tria l
function
Lead II- de te rmine s the function of the
whole he a rt
Lead III- be s t for te s ting the le ft s ide
of the he a rt
* * * Lead II is the most often used* * *

57. Le a d S ys te ms …

58. ***Atta chme nt of the Le a ds ***
BLACK le ft fore a rm
WHITE right fore a rm
RED le ft re a r le g
GREEN right re a r le g
BROWN che s t/grounding

60. Me a s uring the EKG (The Old Wa y)

62. EKG ABNORMALITIES

63. Quick & Dirty Guide to EKG Abnorma litie s
P wave: incre a s e d in a mplitude or
dura tion- a tria l e nla rge me nt.
R wave: incre a s e d in a mplitude - le ft
ve ntricula r e nla rge me nt.
S wave: incre a s e d in a mplitude - right
ve ntricula r e nla rge me nt.

64. Arrhythmia s
An a rrhythmia is a n a bnorma lity in the
ra te , re gula rity, or s ite of origin of the
ca rdia c impuls e .
A dis turba nce in conduction of the
impuls e s uch tha t the norma l s e que nce
of a ctiva tion of the a tria a nd ve ntricle s
is a lte re d.

65. Arrhythmia Inte rpre ta tion
S te p 1: De te rmine the he a rt ra te .
Is it ra pid? S low? Norma l?
S te p 2: As s e s s the rhythm.
S ca n the EKG print out for a bnorma litie s .
S te p 3: Ide ntify the P wa ve s .
A norma l P wa ve indica te s the impuls e origina te d
in the S A node .
Abs e nce of P wa ve s s ignifie s a tria l fibrilla tion or
a tria l s ta nds till.
P wa ve s ma y be s upe rimpos e d on the QRS
comple x in va rious s upra ve ntricula r ta chyca rdia s .

66. Arrhythmia Inte rpre ta tion…
S te p 4: As s e s s the QRS s ha pe &
dura tion.
Abnorma litie s in the s ha pe ca n s ugge s t a
dis turba nce of ve ntricula r impuls e s .

67. Arrhythmia Inte rpre ta tion…
S te p 5: Look a t the re la tions hip be twe e n the
P wa ve s a nd the QRS comple xe s .
Norma lly, the re s hould be one P wa ve for e ve ry
QRS comple x with a cons ta nt P -R inte rva l.
Long P -R inte rva ls indica te a n AV conduction
de la y (1° AV block).
A P wa ve not followe d by a QRS comple x
indica te s 2˚ AV block.
P -R inte rva ls tha t va ry indica te 3˚ AV block.

68. Norma l S inus Rhythm
 P wa ve s a re pos itive .
 QRS comple xe s a re norma l with a cons ta nt P -R
inte rva l.
 This is NORMAL.

69. S INUS IMP ULS E
DIS TURBANCES

70. S inus Arrhythmia
An irre gula r rhythm origina ting in the
S A node .
Re pre s e nte d by a lte rna ting pe riods of
s lowe r & more ra pid he a rt ra te s .
Us ua lly re la te d to re s pira tion:
He a rt ra te incre a s e s with ins pira tion a nd
de cre a s e s with e xpira tion.
A fre que nt norma l finding in the dog.

71. S inus Arrhythmia …
 Ofte n s e e n in bra chyce pha lic bre e ds or in chronic
re s pira tory dis e a s e s , in which va ga l tone is
incre a s e d by uppe r a irwa y obs truction.
 Atropine e limina te s re s pira tory induce d S A.

72. S inus Arrhythmia …

73. S inus Bra dyca rdia
 A re gula r rhythm, with a s low he a rt ra te .
 In ca ts , it is ofte n a s s ocia te d with a s e rious
unde rlying dis orde r, which re quire s imme dia te
a tte ntion.
 Ca us e s - intuba tion, hypothe rmia , & re s pira tory
dis e a s e .

74. S inus Ta chyca rdia
A re gula r s inus rhythm, with a fa s t he a rt ra te .
The mos t common a rrhythmia in dogs a nd
ca ts .
P hys iologic ca us e s include : e xe rcis e , pa in,
or proce dure s involving re s tra int.
P a thologic ca us e s include : fe ve r,
hype rthyroidis m, s hock, a ne mia , infe ction,
CHF, & hypoxia .
Drugs include : a tropine a nd e pine phe rine .

75. S inus Ta chyca rdia …

76. S UP RAVENTRICULAR
IMP ULS E DIS TURBANCES

77. Atria l P re ma ture Contra ctions
Ca us e d by impuls e s origina ting from a
s ite othe r tha n the S A node .
The he a rt ra te is us ua lly norma l.
The P -R inte rva l ma y be long.
A pa us e us ua lly follows a n AP C.
S e e n in both dogs a nd ca ts , us ua lly a
re s ult of a tria l e nla rge me nt (e .g., mitra l
ins ufficie ncy, ca rdiomyopa thy).

78. Atria l P re ma ture Contra ctions …

79. Atria l Ta chyca rdia
A ra pid re gula r rhythm origina ting from a s ite
othe r tha n the S A node .
Thre e or more AP C’s .

80. Atria l Fibrilla tion
Ca us e d by nume rous dis orga nize d
a tria l impuls e s bomba rding the AV
node .
Ha s a ra pid a nd tota lly irre gula r a tria l
a nd ve ntricula r ra te .
No P wa ve s .
Commonly s e e n in conditions
a s s ocia te d with a tria l e nla rge me nt, or
dia lte d ca rdiomyopa thy.

81. Atria l Fibrilla tion…

82. VENTRICULAR IMP ULS E
DIS TURBANCES

83. Ve ntricula r P re ma ture Contra ctions
Ca rdia c impuls e s initia te d in the
ve ntricle s ins te a d of the S A node .
As s ocia te d with we a kne s s , e xe rcis e
intole ra nce , & s udde n de a th.
QRS comple xe s a re typica lly wide a nd
biza rre .
P wa ve s a re dis s ocia te d from the QRS
comple x.

84. Ve ntricula r P re ma ture Contra ctions …
A VP C is us ua lly followe d by a pa us e .
Commonly s e e n in la rge bre e d dogs
with ca rdiomyopa thy, e s pe cia lly boxe rs
a nd Dobie s .
Common in ca ts with ca rdiomyopa thy;
occa s iona lly s e e n in ca ts with
hype rthyroidis m.

85. Ve ntricula r P re ma ture Contra ctions …

86. Ve ntricula r P re ma ture Contra ctions …

87. Ve ntricula r Ta chyca rdia
Thre e or more VP C’s in a row.
The ve ntricula r ra te is >150 bpm.
QRS comple xe s a re wide a nd biza rre .
The re is no re la tions hip be twe e n the P
wa ve s a nd the QRS comple xe s .
The P wa ve s ma y pre ce de , be hidde n
within, or follow the QRS comple xe s .

88. Ve ntricula r Ta chyca rdia …

89. Ve ntricula r Fibrilla tion
Occurs whe n the ce lls of the
ve ntricula r myoca rdium de pola rize in a
cha otic a nd uncoordina te d ma nne r.
No puls e ca n be fe lt a nd ca rdia c
output a pproa che s ze ro.
No QRS comple xe s or P wa ve s .

90. Ve ntricula r Fibrilla tion…
As s ocia te d
conditions include :
S hock,
Myoca rdia l
infa rction,
Ele ctrolyte & a cid-
ba s e imba la nce s ,
Aortic s te nos is
Hypothe rmia

91. Ve ntricula r As ys tole
Indica te s the a bs e nce of a ny
pa ce ma ke r impuls e s .
S ubs e que ntly, the re is no
de pola riza tion or contra ction of the
ve ntricle s .
No puls e ca n be fe lt a nd ca rdia c
output a pproa che s ze ro.
P wa ve s ma y be pre s e nt if the a nima l
ha s comple te AV block.

92. Ve ntricula r As ys tole …
No QRS comple xe s .

93. IMP ULS E CONDUCTION
DIS TURBANCES

94. Atria l S ta nds till
 Cha ra cte rize d by a n a bs e nce of P wa ve s .
 P a tie nts ha ve S A node function, but impuls e s do not
ca us e myocyte a ctiva tion.
 Ca us e s include hype rka le mia a nd a tria l dis e a s e .

95. Firs t-De gre e AV Block
A de la y in the conduction of a n
impuls e through the AV node a nd
bundle of His .
Us ua lly cha ra cte rize d by a prolonge d
P -R inte rva l.
Ge ne ra lly s e e n in olde r pa tie nts
s e conda ry to de ge ne ra tive cha nge s in
the conduction s ys te m.

96. Firs t-De gre e AV Block…

97. S e cond-De gre e AV Block
 Cha ra cte rize d by a n inte rmitte nt fa ilure or dis turba nce of AV
conduction.
 One or more P wa ve s a re not followe d by QRS comple xe s .
 P -R inte rva l is ofte n va ria ble .

98. Third-De gre e AV Block
The ca rdia c impuls e is comple te ly
blocke d in the re gion of the AV
junction.
The P wa ve is norma l.
The QRS comple x is wide a nd biza rre .
The re is no conduction be twe e n the
a tria a nd ve ntricle s .

99. Third-De gre e AV Block…

103. II. Circula tory S ys te m

104. Circula tory S ys te m
Cons is ts of the he a rt, blood ve s s e ls ,
a nd lympha tics .
Blood a cquire s oxyge n in the lungs ,
nutrie nts from the dige s tive tra ct, a nd
hormone s from e ndocrine gla nds .
Blood Vascular System- cons is ts of
blood, he a rt, a rte rie s , ca pilla rie s , &
ve ins .

105. Circula tory S ys te m…
Artery- a ve s s e l ca rrying blood a wa y
from the he a rt.
Ge ne ra lly thicke r a nd s tronge r tha n ve ins .
Capillary- a micros copic ve s s e l tha t
joins othe rs to form a n e xte ns ive
ne twork.
P os itione d be twe e n a rte rie s a nd ve ins .
The y a llow e xcha nge of ga s s e s a nd
nutrie nts be twe e n the blood a nd inte rs titia l
fluid.

106. Circula tory S ys te m…
Veins- ve s s e ls ca rrying blood towa rds
the he a rt.
Thinne r-wa lle d, the y ca rry a gre a te r
volume tha n a rte rie s .

107. Circula tory S ys te m…
Arte rie s  a rte riole s  ca pilla rie s 
ve nule s  ve ins

108. Circula tory S ys te m…
Va lve s in ve ins e ns ure tha t blood
tra ve ls only in the dire ction of the
he a rt.
Cons triction a nd re la xa tion a llow the
va s cula r s ys te m to dire ct blood to
diffe re nt pa rts of the body, a nd to
ma inta in blood pre s s ure whe n blood
volume or ca rdia c output is de cre a s e d.

109. Nota ble Ve s s e ls
Re me mbe r… for e ve ry a rte ry ta king
fre s h blood to the body, the re is a ve in
to ca rry de oxyge na te d blood ba ck to
the he a rt– jus t like on a nd off ra mps to
the “ma jor highwa y!

111. Fe line Thromboe mbolis m
 a .k.a . a s a ddle thrombus
 Cla s s ic pre s e nta tion is pos te rior
pa re s is with we a k or a bs e nt puls e s
in the re a r limbs ; foot pa ds a re
pa le , a nd the toe na ils won’t ble e d
whe n quicke d; the ga s trocne mius
a nd tibia l mus cle s a re rock ha rd by
10-12 hrs pos t-clot
 Aggre s s ive thrombolytic the ra py
ma y be ins titute d if the clinicia n
fe e ls the thrombus is re ce nt (2-4
hrs ) a nd the he a rt dis e a s e is
ma na ge a ble but the prognos is is
s till gua rde d

112. Fe line Thromboe mbolis m (cont)
 Mos t common s ite is a t the
a ortic trifurca tion
 Clinica l s igns de pe nd on
the de gre e of he a rt dis e a s e
a nd the s ite of
thromboe mbolis m
 It ma y be the firs t s ign of
he a rt dis e a s e or
s ome time s ca ts will s how
s e ve re s igns of CHF

113. THE END!