The document provides information on cardiovascular anatomy and physiology for veterinary technicians. It discusses the major components and functions of the cardiac system including the heart chambers and valves, conduction system, blood vessels, and cardiac cycle. It also covers some common cardiac pathologies such as heart failure, valvular disease, patent ductus arteriosus, and persistent right aortic arch.

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!