Cardiology Flashcards
(93 cards)
1
Q
why are cardiac issues much less common in horses than dogs?
A
they have a huge cardiac reserve at rest
2
Q
how do horses with cardiac disease generally present?
A
incidental at pre-purchase exam
poor performance
systemic illness
3
Q
what valve does the most prominent beat occur on?
A
mitral
4
Q
what is the apex beat of the horses heart over?
A
mitral valve
5
Q
what valve is listened to on the right of the horse?
A
tricuspid
6
Q
what is systole and diastole?
A
systole - contraction
diastole - relaxation
7
Q
what causes S1?
A
ventricles contract and the AV valves close (mitral/tricuspid)
8
Q
what causes S2?
A
ventricules relax and semilunar valves shut (aortic/pulmonic)
9
Q
what causes S4?
A
atrial contraction
10
Q
when is S4 heard?
A
just before S1
11
Q
what causes S3?
A
end of rapid ventricular filling (difficult to hear)
12
Q
when is S3 heard?
A
just after S2
13
Q
why does mitral valve regurgitation cause a loud S3?
A
there is more blood in the atria due to the regurgitation so ventricular filling is even faster due to the pressure
14
Q
how does the length of systole compare to diastole in the normal heart beat?
A
systole is much shorter
15
Q
how does the length of systole compare to diastole with a fast heart beat?
A
systole and diastole become much similar in length
16
Q
what is a murmur?
A
turbulent flow of blood
17
Q
turbulence of blood is influence by Reynolds number, what is Reynolds number influenced by?
A
vessel diameter
blood velocity
blood density
18
Q
how is a grade 1 murmur described?
A
barely audible
19
Q
how is a grade 2 murmur described?
A
definite murmur quieter than S1 and S2
20
Q
how is a grade 3 murmur described?
A
obvious loud murmur as loud and S1 and S2
21
Q
how is a grade 4 murmur described?
A
very loud murmur louder than S1 and S2
22
Q
how is a grade 5 murmur described?
A
very loud with a palpable thrill
23
Q
how is a grade 6 murmur described?
A
audible with stethoscope just off chest wall
24
Q
how can the timing of a murmur be described?
A
systolic
diastolic
continuous
(mid, early, late, pan, holo)
25
what ways can a murmur be described?
grade
timing
point of maximal intensity
radiation
shape of murmur
quality of murmur
26
how would a murmur from aortic valve regurgitation be described?
holodiastolic
between aorta and left ventricle
decrescendo
27
how would a murmur from mitral valve regurgitation be described?
holosystolic
between left atrium and ventricle
plateau
28
what are the two categories of murmurs?
physiological (functional)
pathological
29
when is an aortic flow murmur heard?
early-mid systole
30
where is an aortic flow murmur localised to?
heart base
31
what are the two main physiological murmurs?
flow and filling
32
when is a filling murmur heard?
early diastole
33
what animals is a filling murmur heard in?
fit young horses
34
what sound does a filling murmur make?
squeak/whoop
35
how would the murmur heard with mitral/tricuspid regurgitation be described?
holo/pansystolic
plateau or crescendo
PMI heart apex
36
why is tricuspid regurgitation less severe than mitral?
right side of heart (tricuspid) is under less pressure
37
how would a ventricular septal defect murmur be described?
loudest on right
pansystolic
radiates cranial/ventral
38
how would an aortic insufficiency murmur be described?
decrescendo (buzzing)
holodiastolic
PMI left heart base
39
what age horses is an aortic insufficiency murmur heart in?
teenage (moaning sound)
40
why is a patent ductus arteriosus murmur a constant murmur?
because there is always a pressure gradient
41
what age horses is patent ductus arteriosus murmur common in?
young horses (first 5 days of life)
42
what is oedema?
abnormal and excessive accumulation of fluid in the interstium
43
how does generalised oedema often present in horses?
accumulated in the lowermost part of the body (dependant oedema)
44
how is excess fluid drained from the interstitial space?
via the lymphatic system
45
what causes fluid to leave the vessels at the arterial end of capillaries?
hydrostatic pressure
46
what causes fluid to enter the vessel at the venous end of the capillary?
oncotic pressure
47
what are the four mechanisms that can cause oedema?
increased capillary hydrostatic pressure
decreased capillary oncotic pressure
lymphatic obstruction
increased capillary permeability
48
what are some possible causes of decreased oncotic pressure?
protein losing enteropathy
protein losing nephropathy
haemorrhage
chronic hepatopathy
49
what are some possible causes of lymphatic obstruction?
confinement (standing still for too long)
tumours
post-partum
lymphangitis
50
what are the three main causes of increased vascular permeability?
vasculitis
SIRS (endotoxaemia)
local inflammation
51
what happens to white blood cells in cases of SIRS?
they stick to the blood vessel walls
52
what happens when neutrophils stick to blood vessel walls in cases of SIRS?
causes damage to the wall
53
why do gums become congested in SIRS cases?
body loses ability to send blood to places that need them the most - generalise vasodilation
54
does losing a gram of globulin or albumin from blood have more effect on the oncotic pressure?
albumin (smaller molecule so more molecules are lost per gram)
55
what are some possible infectious causes of vasculitis?
infectious equine viral arteritis
herpes virus 1
infectious anaemia
Hendra
African horse sickness
56
what are the possible routes of transmission of infectious equine viral arteritis?
respiratory or venereal
57
what are the possible clinical signs of infectious equine viral arteritis?
pyrexia, dull, oedema, stiff gait, abortion, respiratory disease
58
what can cause an immune mediated vasculitis?
allergy/hypersensitivity
59
what is a severe generalised immune mediated vasculitis called?
purpura haemorrhagica
60
what types of hypersensitivity can cause a vasculitis?
1 - IgE
3 - immune complex
61
what parasite is associated with verminous vasculitis?
Stongylus vulgaris
62
what is the most common place for an aneurysm/rupture in stallions?
aortic root
63
what is thrombophlebitis?
blood clot that sticks to an inflamed vessel wall
64
where is thrombosis common in horses?
aortic-iliac
jugular from catheterisation
65
what is lymphangitis?
inflammation/infection of lymph vessels
66
how does lywmphantiis usually present?
swollen leg, painful on palpation but can bear weight
67
how is lymphangitis treated?
NSAIDs
possible antimicrobials
topical cleaning and cold treatment
encourage walking and movement
68
what is the function ion the AV node?
slow the wave of depolarisation down to prevent the atria and ventricles contracting at the same time
69
what is the point of the refractory period in cardiomyocytes?
to ensure it cannot contract again straight away
70
what factors can alter the resting and threshold potential of cells?
autonomic nervous system
potassium, sodium and calcium concentrations inside compared to outside of the cell
drugs
71
what effect will the parasympathetic system have on the heart?
triggers acetylcholine release which opens potassium channels on the pacemaker cells which lowers the resting potential meaning it will take longer to reach the threshold potential
72
where are the electrodes placed for equine ECG?
left arm (positive) - heart apex
right arm (negative) - mid right jugular furrow
73
what does the P wave show on ECG?
atrial depolarisation
74
what does the P-R interval of an ECG show?
AV node slowing the depolarisation
75
what does the QRS complex show on an ECG?
ventricular depolarisation (atria depolarises here)
76
what does the T wave of an ECG show?
ventricular repolarisation
77
what are the common arrhythmias in horses?
first/second degree AV block
sinus arrhythmias and tachycardia/bradycardia
atrial premature complexes
atrial fibrillation
ventricular premature complexes
ventricular tachycardia
78
what happens during second degree AV block?
regular SA node depolarisation and conduction pathway but AV node stops the spread of depolarisation every 3-4 beats
79
what heart sound can be heard when there is a dropped beat due to second degree AV block?
S4
80
is second degree AV block pathological or physiological in horses?
physiological - often clears with sympathetic tone (exercise....) - resting horses
80
is second degree AV block pathological or physiological in horses?
physiological - often clears with sympathetic tone (exercise....) - resting horses
81
what happens on an ECG during a first degree AV block?
prolonged P-R complex
82
what happens on an ECG with sinus arrhythmias?
P-R interval waxes and wanes
83
what does atrial fibrillation sound like?
trainers in a washing machine - all the beats but completely random
84
what are the most common presenting complaints of horses with atrial fibrillation?
poor performance
fading during a race
epistaxis
(incidental in low work horses)
85
what is the treatment for atrial fibrillation based on?
increasing the refractory period to prevent the wave being able to continue around the atria
86
what is the prognosis for horses with secondary atrial fibrillation?
poor - don't bother treating
87
what are the main options for cardioversion to treat atrial fibrillation?
pharmacologic conversion (quinidine sulphate)
transvenous electrical cardioversion
88
what are the side effects for quinidine sulphate used to treat atrial fibrillation due to?
blockage of sodium channels (GI tract, nervous, muscles...)
89
why are currents for transverse electrical cardioversion placed on the skin?
would create too much heat as too higher current would be required so it would cook the animal
90
what is done to see if a horse with atrial fibrillation is safe to ride?
do an exercising ECG to look for rhythms and determine risk of collapse - looking to see if it alters the ventricular beats
91
what causes an atrial premature complex?
ectopic pacemaker in the atria (oddly shaped P wave)
92
how is it determined if the ectopic pacemaker is atrial or ventricular?
atrial - P wave effected
ventricular - QRS wave effected
