Cardiology Flashcards
(280 cards)
1
Q
what is the most common heart disease of dogs?
A
myxomatous degenerative valve disease
2
Q
what age animals are effected by myxomatous degenerative valve disease?
A
older animals (it is a degenerative disease)
3
Q
what valves are effected by myxomatous degenerative valve disease?
A
mitral and tricuspid
4
Q
what breeds are effected by myxomatous degenerative valve disease?
A
small breed dogs (cavalier King Charles spaniel…)
5
Q
what are some possible diseases causing valves to leak?
A
myxomatous degenerative valve disease
mitral dysplasia
mitral regurgitation (DCM)
endocarditis
6
Q
what age dogs are effected by mitral dysplasia?
A
young dogs - congenital condition
7
Q
what breed dogs are effected by mitral dysplasia?
A
large breed dogs
8
Q
what does the myxoma part of myxomatous degenerative valve disease relate to?
A
nodular thickening of valve leaflets
9
Q
what causes the thinking of the valve leaflets in myxomatous degenerative valve disease?
A
accumulation of collagen based material (glycosaminoglycan and proteoglycan)
10
Q
over tike what does the nodular thickening of valve leaflets caused by myxomatous degenerative valve disease lead to?
A
lengthening and rupture of the chordae
11
Q
what are the gross pathological findings of hearts with myxomatous degenerative valve disease?
A
left atrial dilation
left ventricle dilation
elongated chordae tendinae
thickened leaflets
jet lesions
12
Q
what pathological histology is found in cases of myxomatous degenerative valve disease?
A
accumulation of glycosaminoglycan (dark purple)
13
Q
what happens to blood if the mitral valve leaks?
A
blood leaks back into the left atria
14
Q
what does leakage of blood back into the left atria due to a mitral valve leak cause?
A
reduction in stroke volume (blood leaving the heart)
15
Q
since blood has leaked back into the left atrium due to a mitral valve leak, what happens in the next diastole?
A
the volume of blood entering the left ventricle increases (volume overload)
16
Q
why does regurgitant blood flow into the left atrium if the mitral valve is leaky?
A
because the left atrium is under lower pressure so the afterload is reduced and it is easier for blood to flow back into the atrium than out the aorta
17
Q
why does preload increase of the left ventricle increase in cases of myxomatous degenerative valve disease?
A
there is a higher volume of blood in the ventricle at the end of diastole (filling phase) because its got its normal input from the atrium plus the regurgitant blood
18
Q
why is stroke volume of the left ventricle reduced in myxomatous degenerative valve disease?
A
regurgitant blood flows back into the atrium instead of our of the aorta
19
Q
what does the reduced stroke volume in animals with myxomatous degenerative valve disease activate?
A
RAAS
20
Q
what does volume overload of the left ventricle lead to?
A
eccentric hypertrophy
21
Q
what does RAAS aim to do once activated due to reduced stroke volume?
A
increase circulating volume and cause vasoconstriction
22
Q
what happens in neurohumoral activation due to myxomatous degenerative valve disease?
A
sympathetic nervous system activated - tachycardia, positive inotrope, vasoconstriction
RAAS - sodium/water retention, increased circulatory volume, vasoconstriction
remodelling - eccentric hypertrophy
23
Q
what is the negative sequelae of chronic sympathetic nervous system activation from myxomatous degenerative valve disease?
A
cardiomyocytes require more oxygen, can’t get this so die
intracellular calcium overload leads to toxic death for cardiomyocytes
(these both then decrease the systolic function of the heart)
24
Q
what is the negative sequelae of chronic RAAS activation from myxomatous degenerative valve disease?
A
increases circulatory volume to increase the workload of the heart
25
what is the negative sequelae of chronic remodelling (eccentric hypertrophy) from myxomatous degenerative valve disease?
fibrosis (poor contractility)
increased wall stress
26
what are categories for staging myxomatous degenerative valve disease?
A - at risk
B1 - murmur and no enlargement
B2 - murmur and enlargement
C1 - CHF (hospitalised)
C2 - CHF (home)
D1 - refractory (hospitalised)
D2 - refractory (home)
27
how is the murmur associated with myxomatous degenerative valve disease described?
loud harsh left apical systolic murmur (in an old animal)
28
what biochemical marker is used for myxomatous degenerative valve disease?
NTProBNP
29
what is NTProBNP a measure of?
wall stress
30
why is hypertension in myxomatous degenerative valve disease cases bad?
increased afterload meaning the regurgitant fraction of blood will be worse meaning the disease will progress faster
31
what is NTProBNP an indirect measure of?
heart size
32
other than NTProBNP, what other biomarker can be used for myxomatous degenerative valve disease?
troponin I
33
what does troponin I measure?
heart damage
34
if the patient is on diuretics, what should be monitored carefully?
kidney function
35
where are veins found on thoracic radiographs?
ventral and central
36
what arrhythmia means a dog isn't in heart failure?
sinus arrhythmia
37
what signs seen on echocardiography are indicative of myxomatous degenerative valve disease?
enlarged left atrium (LA>LV)
significant mitral regurgitation
dilated left ventricle
rounded left ventricle
hyperdynamic systolic function
tricuspid regurgitation
38
how big should the left atrium be compared to the aorta?
no more than 1.5x
39
how can the staging of myxomatous degenerative valve disease be remembered?
A - at risk
B - broken but ok
C - congested
D - dying
40
what does at risk me on myxomatous degenerative valve disease staging?
any animal predisposed to myxomatous degenerative valve disease (small breed dogs)
41
what is the difference in treatment for B1 and B2 myxomatous degenerative valve disease?
pimobendan is given to B2 (not B1)
42
if a B1 myxomatous degenerative valve disease animal is found, what should be done in term of treatment?
nothing but run a NTProBNP every month, as soon as this increases start treatment
43
what treatment is started when a dog is in myxomatous degenerative valve disease stage C?
furosemide
pimobendan
ACE inhibitors
spironolactone
44
what are the four drugs available for heart failure?
furosemide
pimobendan
ACE inhibitors
spironolactone
45
what is a good nutraceutical that can be used for heart failure?
omega 3 fish oils
taurine
46
what are some good predictors of a negative outcome of myxomatous degenerative valve disease?
left ventricular dimensions
left atrial enlargement
rupture of major chorda
NTProBNP
47
what is endocarditis?
infection of one or more endocardial surfaces (valves) - typically the mitral and aortic in smallies
48
what are the requirements for an animal to develop endocarditis?
bacteraemia
damaged endothelium
ability for bacteria to adhere
hypercoagulable state
49
what is the prognosis of endocarditis?
very guarded (rare to see as animals often just die)
50
what is a cardiomyopathy?
myocardial disorder in which the heart muscle is structurally or functionally abnormal
51
what is the most common primary cardiomyopathy in dogs?
dilated cardiomyopathy (DCM)
52
what dogs are predisposed to DCM?
older large breed dogs (dobermans and Great Danes)
53
what is the prognosis for dogs with DCM?
guarded (CHF and sudden death)
54
what is the overall effect that DCM has on the heart?
decreases contractility (impaired systolic function and dilated chambers)
55
what is the aetiology of DCM?
idiopathic
secondary causes (DCM like phenotype)
genetically predisposed
56
how does a DCM heart appear grossly?
dilated 4 chambers (left ventricle more than atrium) - left side more than right
mitral/tricuspid annulus stretch (leakage)
ball shaped heart
57
how does the pathology of the heart appear histologically in DCM hearts?
attenuated fibres (atrophied) - thin and fibrosis
myocyte lysis
58
what effect does the impaired systolic function with DCM effect the heart?
reduces the cardiac output
59
what does the reduced cardiac output associated with DCM trigger?
RAAS
sympathetic nervous system
60
what negative impact does RAAS and sympathetic nervous system activation have on the heart?
increased HR and contractility - myocardial hypertrophy leading to increased oxygen demand and myocardial death
61
how does vasoconstriction caused by sympathetic activation and DCM due to DCM effect the heart?
increased blood pressure meaning afterload increases which means the heart has to contract/work harder
62
why do the mitral/tricuspid valves become leaky in DCM cases?
the valves become stretched open due to heart dilation
63
what are the similarities between DCM and myxomatous degenerative valve disease?
enlarged left ventricle and atrium
mitral regurgitation
64
what are the differences between mitral regurgitation in myxomatous degenerative valve disease and DCM?
DCM has mild mitral regurgitation and myxomatous degenerative valve disease has severe
65
what are the differences between systolic function in myxomatous degenerative valve disease and DCM?
DCM has reduced systolic function but it is normal/greater in myxomatous degenerative valve disease
66
what are the differences between ventricular/atrial size in myxomatous degenerative valve disease and DCM?
DCM the left ventricle is bigger than the atrium but its the opposite in myxomatous degenerative valve disease
67
what is DCM in cocker spaniels associated with?
taurine deficiency
68
what is the main breed that is predisposed to arrhythmogenic right ventricular cardiomyopathy?
boxers (bull type breeds)
69
what are the gross pathological changes associated with arrhythmogenic right ventricular cardiomyopathy?
right ventricular dilation
wall thinning
70
what are the histological pathological changes associated with arrhythmogenic right ventricular cardiomyopathy?
loss of myocytes, they're replaced by fatty deposits
71
what are the three possible presentations of arrhythmogenic right ventricular cardiomyopathy?
asymptomatic with ventricular arrhythmias
sympathetic with ventricular arrhythmias
ventricular dilation, myocardial dysfunction with/without arrhythmias
72
what breeds are predisposed to atrial cardiomyopathy?
English springer spaniel
labrador
73
what are the gross pathological signs of atrial cardiomyopathy?
thin atrial walls
74
what heart rhythm is associated with atrial cardiomyopathy?
atrial standstill (escape rhythm with no P wave)
75
what breeds are predisposed to canine hypertrophic cardiomyopathy?
terriers, pointers, golden retrievers
76
what are some possible causes of secondary cardiomyopathy?
myocarditis
tachycardia induced cardiomyopathy
taurine deficiency
77
what type of diet should a breed at risk of taurine deficiency not be on?
grain free diet is not advised
78
what type of murmur is heart in DCM patients?
quiet soft left apical systolic heart murmur
79
what are the features that would make you suspicious that a dog has DCM?
large breed
arrhythmia
quiet left apical systolic murmur
dyspnoea and tachypnoea
collapsed adult dog
(may have no clinical signs)
80
what is the best biomarker for DCM?
troponin I (disease is in the myocardium - shows damage)
NTProBNP (wall stretch)
81
what organ should be checked in cases of suspected DCM?
thyroid (hyperthyroid contributes to systolic dysfunction)
82
what are the signs of DCM on echocardiography?
enlarged left ventricle/atrium
dilated left ventricle
rounded left ventricle
thin walls
reduced systolic function
83
what is used to screen for DCM?
holter (ambulatory ECG)
84
what therapy is used for preclinical DCM?
pimobendan (9 months additional time clinical sign free)
85
if DCM progresses to congestive heart failure, what is done to treat it?
furosemide
pimobendan
ACE inhibitors
spironolactone
86
if an animal on pimobendan goes into heart failure, what treatment should be given?
furosemide first then other drugs for heart failure if they can afford it
87
what are negative prognostic indicators for DCM dogs?
young age
ascites
dyspnoea
atrial fibrillation
88
what are some examples of primary feline myocardial disease?
hypertrophic cardiomyopathy
restrictive cardiomyopathy
non-specific cardiomyopathy
dilated cardiomyopathy
arrhythmogenic right ventricular cardiomyopathy
89
what are some secondary myocardial diseases?
hypertensive cardiomyopathy
hyperthyroid cardiomyopathy
cardiomyopathy associated with acromegaly, azotaemia, diabetes...
90
what is acromegaly?
excess of growth hormone
91
what are the classic histological findings of a heart of a cat with feline hypertrophic cardiomyopathy?
cardiomyocyte fibre disarray and replacement fibrosis
92
what cats is hypertrophic cardiomyopathy most common in?
large males
over weight cats
93
what causes feline hypertrophic cardiomyopathy?
environmental (overweight, males...)
genetic (Maine coons, ragdolls...)
94
how are most cats with hypertrophic cardiomyopathy detected?
asymptomatic heart murmur (sometimes arrhythmias, diastolic gallops...)
95
what biomarkers are used to detect feline hypertrophic cardiomyopathy?
increased NTpro-BNP
troponin I
96
how do clinical cases of feline hypertrophic cardiomyopathy present?
dyspnoea, tachypnoea, congestive heart failure, pleural effusion
feline arterial thrombo-embolism
syncope
open mouth panting
sudden death
97
what is the most common place to find feline arterial thromboembolism-embolism (FATE)?
external iliac artery bifurcation (saddle thrombus)
98
what are the clinical signs of feline arterial thromboembolism-embolism?
pain, purple footpads
off its back legs
99
how can feline hypertrophic cardiomyopathy be classified?
A - predisposed
B1 - normal/mild atrial enlargement
B2 - moderate/severe atrial enlargement
C - CHF
D - refractory CHF
100
how do hearts of cats with feline hypertrophic cardiomyopathy appear of DV radiographs?
"shoulder pads" - big atrial appendages
101
how can an ECG of a cat with feline hypertrophic cardiomyopathy appear?
can be unremarkable
tall R wave - LV enlargement
intraventricular conduction disturbances
102
what causes the murmur associated with feline hypertrophic cardiomyopathy?
left ventricular hypertrophy causes a septal bulge meaning in changes the direction of blood flowing out of the ventricle
can suck the mitral valve into the ventricle (systolic anterior motion) - further narrowing the outflow tract and causing regurgitation into the atrium
103
other than murmurs, what other heart sounds can be heard in cases of feline hypertrophic cardiomyopathy?
S3 - rapid deceleration of blood in LV
S4 - LV filling associated with atrial contraction
(diastolic gallops)
104
what is used to treat cats with hypertrophic cardiomyopathy and CHF?
diuretics (furosemide)
venodilator (if life threatening pulmonary oedema)
ACE inhibitors
prevent thromboembolism (clopidogrel)
105
when would a venodilator be used in cases of feline hypertrophic cardiomyopathy and CHF?
if there is a life-threatening oedema
106
what treatment can be used in asymptomatic feline hypertrophic cardiomyopathy, but never with CHF?
beta blockers
107
what is used to treat asymptomatic feline hypertrophic cardiomyopathy?
beta blockers (atenolol)
ACE inhibitors
diltiazem (positive lusitrope)
108
what must be excluded on diagnosis of feline dilated cardiomyopathy?
taurine deficiency (assess response to taurine supplementation)
109
what treatments are commonly used in feline dilated cardiomyopathy cases?
warmth and humidified oxygen
drain effusions
furosemide
ACE inhibitors
pimobendan (positive inotrope)
110
what are the two forms of restrictive cardiomyopathy?
myocardial
endocardial
111
what are the characteristic features of feline restrictive cardiomyopathy?
normal LV wall measurement
normal LV chamber dimensions
normal LV systolic function
marked LA enlargement
112
when is a cardiomyopathy described as non-specific?
if there are features of more than one form of cardiomyopathy
113
how does the heart of cats with arrhythmogenic RV cardiomyopathy appear?
bigger right side of the heart than left
fatty replacement of myocardium (impaired contraction)
114
why is the contraction of hearts with arrhythmogenic RV cardiomyopathy impaired?
myocardium is replaced by fatty deposits
115
whatever the form of feline cardiomyopathy, what is used to treat CHF?
furosemide
pimobendan
ACE inhibitor
spironolactone
116
what is the easiest way to screen for feline cardiomyopathies?
NTpro-BNP
117
what are the two layers of pericardium?
outer (fibrous)
inner (serous)
118
what are the two parts of the inner layer of the pericardium?
parietal and visceral
119
what is the function of the pericardium?
protection (fluid and lubricant)
prevents over dilation
coordinate left and right ventricular interaction
maintains position in mediastinum
120
what are the general causes of pericardial effusion in cats?
congestive heart failure
FIP
infectious, lymphoma...
121
what are the general causes of pericardial effusion in dogs?
idiopathic
neoplasia
122
what dog breeds are predisposed to idiopathic pericardial effusion?
large breeds - st Bernard, Labrador...
123
what is the most common neoplastic cause of pericardial effusion in dogs with a poor prognosis?
haemangiosarcoma
124
how long does it take for idiopathic pericardial effusions to build up in dogs?
chronic long term
125
how long does it take for neoplastic pericardial effusions to build up in dogs?
acute presentation
126
what dogs are predisposed to haemangiosarcoma pericardial effusions?
German Shepherds
127
what is the most common location of haemangiosarcomas on the heart?
right atrium
128
why should the abdomen be looked at if a haemangiosarcoma is found on the heart?
they are extremely metastatic (poor prognosis)
129
what is the fluid in a pericardial effusion caused by a haemangiosarcoma?
blood from haemangiosarcoma bleeding (difficult to perform pericardiocentesis as it can keep bleeding)
130
what is a neoplastic cause of pericardial effusion in dogs that has a good prognosis?
chemodectoma
131
what are other names for a chemodectoma?
aortic body tumour
heart base tumour
132
what dog breeds are predisposed to chemodectoma?
brachycephalic
133
why is the prognosis of dogs with a chemodectoma generally good?
slow growing benign tumours with low metazoic rate
134
is the prognosis for a mesothelioma causing pericardial effusion good or bad?
poor prognosis
135
why is mesothelioma difficult to diagnose?
everywhere has mesothelial cells that will become inflamed and angry when sampled
136
which chamber of the heart gets compressed most by pericardial effusions?
right atrium (lowest pressure) - followed by right ventricle
137
why does volume overload occur with pericardial effusions?
decreased right ventricular filling leads to less blood entering left atrium and ventricle which means less cardiac output and hence RAA activation
138
why does oedema occur elsewhere in the body when pericardial effusion is present?
RAAS activated to increase volume and there is less venous return to heart due to pressure in right side, this causes an increase in venous and capillary pressure causing leakage
139
what is pulses paradoxus caused by pericardial effusion?
when animal breathes in they appear dead (no/weak femoral pulse) - less output from the left side of heart
140
what is cardiac tamponade?
increased intrapericardial pressure leads to right atrium and ventricle collapsing in diastole which impairs cardiac filling and output (results in CHF)
141
why does the right atrium collapse during diastole in cardiac tamponade cases?
this is when the pressure is at the very lowest (heart relaxed)
142
what are the specific signs of a dog with pericardial effusion?
abdominal enlargment
decreased exercise tolerance
mild cough
syncope/collapse
143
what are the non-specific signs of pericardial effusion ion dogs?
decreased appetite (all organs become congested and full - makes animal feel full)
lethargy
GI upset
144
what are the clinical signs of chronic pericardial effusion in dogs?
right sided CHF (organomegally, abdominal effusion, positive hepatojugular reflux, tachycardia...)
weak femoral pulse
muffled heart sound
145
what are the clinical signs of acute pericardial effusions in dogs?
weak
collapsed
tachycardia (possible arrhythmias)
pale MM
haemorrhagic shock
weak pulse
146
what is the quickest way to diagnose a pericardial effusion?
T-FAST
147
before performing pericardiocentesis what should be done?
check PCV
haematology, biochemistry
troponin I (cell death marker)
coagulation (if concerned)
blood pressure
ECG
148
why should troponin I be done before pericardiocentesis?
so you can see if the damage is caused by the tumour or if you cause the damage by jabbing the heart
149
what should be done to the fluid obtained from the pericardiocentesis?
send for analysis
150
how does an ECG change after a pericardiocentesis?
heart rate falls
QRS complex becomes bigger
151
how does a pericardial effusion appear on radiography?
perfectly circular cardiac silhouette and large caudal vena cava
152
what drug should not be used in dogs with a pericardial effusion?
furosemide (will kill them)
153
why shouldn't furosemide be used in dogs with pericardial effusion?
already struggling to get blood into the heart - reducing the blood volume will mean even less goes in the heart
154
how should you position a dog to do a pericardiocentesis?
left lateral recumbency (main coronary vessel is on the left)
155
where is the needle placed for pericardiocentesis?
5th - 6th intercostal space
156
what sized catheter is used for pericardiocentesis?
14G over needle catheter (with side holes)
157
how will the fluid of pericardial effusions appear when drained?
look like blood (even benign idiopathic cases)
158
what will you see in the patient if you have placed your needle in the correct place and you are draining the pericardial effusion?
reduced HR
improved pallor
improved pulse
taller QRS on ECG
159
what should be done if you're carrying out a pericardiocentesis and the patient isn't improving?
check PCV - couldn't be draining whole blood and exsanguinating patient
160
what will happen immediately after pericardiocentesis?
dog will need to wee - natural diuresis as ascites resolve
161
what is constrictive pericarditis?
pericardium becomes thickened and fibrotic (looks like pericardial effusion without the fluid)
162
how is constructive pericarditis treated?
pericardectomy
163
what does PPDH stand for?
peritoneal pericardial diaphragmatic hernia
164
what is the cause of PPDH?
congenital - failure of ventral diaphragm and pericardium to close properly (abdominal organs in pericardial sac)
165
what are some differential diagnoses for heart murmurs in puppies?
innocent flow murmur
anaemia
congenital heart disease
166
what causes an innocent flow murmur in puppies?
foetal haemoglobin and lower PCV (alters blood viscosity)
167
how would an innocent flow murmur of a puppy be described?
low grade, systolic, musical, localised to left heart base
168
what is a patent ductus arteriosus?
ductus arteriosus doesn't close and connects the descending aorta to the pulmonary artery
169
where does blood flow in a patent ductus arteriosus?
from aorta to pulmonary artery (continuous shunt - diastole and systole)
170
what happens to the pulmonary circulation in patent ductus arteriosus cases?
more blood forced through the pulmonary circulation leading to a left sided volume overload (see an increase in pulmonary vessel size on radiograph)
171
how is the murmur associated with patent ductus arteriosus described?
continuous, localised dorsally (left axilla), high grade (can feel it with hands)
172
what can happen to the mitral valve due to volume overload caused by patent ductus arteriosus?
dilation of the valve annulus leading to secondary mitral regurgitation
173
what species is patent ductus arteriosus most commonly seen in?
dogs (rare in cats) - bitches more common than males
174
what breeds are predisposed to patent ductus arteriosus?
German shepherd
collies
bichon frise
poodle
cavalier king Charles
irish setter
175
what can cause a secondary murmur in patent ductus arteriosus cases?
mitral regurgitation
176
what radiographic findings are present in patent ductus arteriosus cases?
left atrial/ventricle enlargement
triple knuckle (aortic, pulmonic, left auricular appendage bulge)
increased arteries/veins in pulmonary circulation
177
what evidence of a patent ductus arteriosus could be seen on an ECG?
P mitrale
very tall R wave (atrial enlargment)
178
how is patent ductus arteriosus treated?
surgical closure as soon as possible
catheterisation based occlusion of PDA
179
what type of hypertrophy is seen in cases of subaortic stenosis?
concentric hypertrophy of left ventricle (pressure overload)
180
what is the most common congenital heart defect in dogs?
aortic stenosis
181
what breeds are predisposed to aortic stenos?
boxers
newfoundlands
golden retrievers
rottweilers
bull terrier
182
what effect can the concentric hypertrophy due to aortic stenosis have on the coronary perfusion?
decreased as the vessels are squashed
larger mass of muscle so coronary system struggles to supplyenough blood
183
how would a murmur caused by aortic stenosis be described?
harsh mid to holosystolic
grade corresponds to severity
radiates up carotids (right side of chest)
184
what can occasionally happen in aortic stenosis cases that causes a diastolic murmur?
aortic regurgitation due to a faulty aortic valve
185
what pressure gradient would mild, moderate and severe aortic stenosis have?
mild - <50mmHg
moderate - 50-80mmHg
severe - >80mmHg
186
what breeds have a scheme to prevent breeding from dogs with aortic stenosis?
boxers and newfoundlands
187
how is aortic stenosis treated?
no surgical treatment available
poor prognosis - often sudden death and CHF
188
are the lesions of pulmonic stenosis usually subvalvular, valvular or supravalvular?
valvular
189
what type of hypertrophy is seen with pulmonic stenosis?
concentric right ventricular hypertrophy (pressure overload)
190
what breeds are predisposed to pulmonic stenosis?
cocker spaniel
cavalier king Charles
terrier
beagle
bulldogs
boxer
191
what are the clinical signs of pulmonic stenosis?
heart murmur, exercise intolerance, syncope
192
how would the murmur associated with pulmonic stenosis be described?
mid to holosystolic cranially on the left heart base
radiates dorsally
193
how does pulmonic stenosis appear on a radiograph?
large right side of heart (lots of sternal contact) - lateral view
large pulmonary artery
194
how would an ECG appear in cases of pulmonic stenosis?
negative QRS complex in lead one - right axis deviation (larger right side of heart)
195
what can be done to treat pulmonic stenosis?
cardiac catheterisation - balloon valvuloplasty (usually works well)
surgical
196
what happens to blood flow in ventricular septal defect cases?
blood shunted from left to right ventricle
197
is ventricular septal defect more common in dogs or cats?
cats
198
how does the murmur grade correlate with the severity of the ventricular septal defect?
inversely proportional
199
why is the grade of the murmur inversely proportional to the severity of the ventricular septal defect?
small defects will maintain the pressure gradient between right and left ventricle so the flow through it will be very fats causing more turbulent flow and a louder murmur
200
how is the murmur associated with ventricular septal defects described?
systolic murmur
right hemithorax is point of maximum intensity
201
why may ventricular septal defects cause a relative pulmonic stenosis?
there is more blood in the right ventricle so more needs to exit via the pulmonic valve, giving the appearance of a stenosis
202
what type of hypertrophy occurs in the right ventricle in cases of ventricular septal defects?
eccentric hypertrophy (volume overload)
203
what type of hypertrophy occurs in the left atrium and ventricle in ventricular septal defect cases?
eccentric hypertrophy (volume overload due to pulmonary over circulation)
204
what are possible sequelae for ventricular septal defects?
can remain asymptomatic
left sided heart failure (large defects)
some can close
prolpase of aortic valve (aortic regurgitation)
right to left shunt due to pulmoinary hypertension
205
what is a right to left shunt in patent ductus arteriosus cases known as?
eisenmengers syndrome
206
is atrioventricular valve dysplasia more common in cats or dogs?
cats
207
what dog breeds are predisposed to mitral dysplasia?
bull terrier
golden retriever
great dane
German shepherd
208
what dog breeds are predisposed to tricuspid dysplasia?
labradors
209
what type of hypertrophy is seen with mitral valve dysplasia?
volume overload of left side of heart causing eccentric hypertrophy
210
what type of hypertrophy is seen with tricuspid valve dysplasia?
volume overload of right side of heart causing concentric hypertrophy
211
how harsh is the murmur heart with atrial septal defects?
low grade as there isn't much of a pressure gradient
212
what are the defects of the tetralogy of fallot?
pulmonic stenosis
right ventricular hypertrophy
ventricular septal defect
dextraposed aorta
213
what can cause constriction at the heart base leading to megaoesophagus?
persistant right fourth aortic arch (vascular ring abnormality)
214
how can cardiac arrhythmias be divided?
Brady/tachy
supraventricular/ventricular
sustained/paroxysmal
215
what can be used for a long term ECG monitor?
holter
reveal LINQ device (placed into chest) - device can stay in for 2 years and memorise the loop of ECG
216
what can tachyarrhythmias be divided into?
supraventricular (narrow QRS complex)
ventricular (wide bizarre QRS complex)
217
what is the general appearance of an ECG of a supraventricular tachycardia?
narrow normal QRS
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what is the general appearance of an ECG of a ventricular tachycardia?
wide bizarre QRS complex
oppositely directed T wave
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what do anti-arrhythmic drugs effect?
action potential
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what are the classes of anti-arrhythmic drugs?
1 - sodium channel blocker
2 - beta blockers
3 - potassium channel blockers
4 - calcium channel blockers
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what phase of action potential do class 1 anti-arrhythmic drugs effect?
sodium channel blockers effect phase 0 (steepness of phase 0 decreases)
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what tissue do class 2 anti-arrhythmics mainly effect?
nodal tissue
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what phase of the action potential do class 2 anti-arrhythmic effect?
beta blockers effect phase 4 making the resting potential and slower depolarisation
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what phase of the action potential do class 3 anti-arrhythmic drugs effect?
potassium channel blockers lengths the action potential duration by delaying repolarisation
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what tissue do class 4 anti-arrhythmic drugs mainly act on?
nodal - AV and SA
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what causes sinus tachycardia?
can be physiological - response to pain, stress...
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what is an example of a re-entry circuit causing a supraventricular tachycardia?
atrial fibrillation
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what are the majority of pathological supraventricular tachyarrhythmias due to?
ectopic focus
accessory pathway
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how can atrial fibrillation be differentiated from supraventricular tachyarrhythmias?
atrial fibrillation has an irregular R-R interval
supraventricular tachycardias are regular
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what is used from emergency treatment of supraventricular tachyarrhythmias?
vagal manoeuvre
IV esmolol (beta blocker)
IV/oral diltiazem
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what is a vagal manoeuvre?
physically increasing vagal tone to Av node by such things as using ocular pressure (squeezing closed eye)
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what class of anti-arrhythmic drug is esmolol?
beta blocker (very short acting)
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what class of anti-arrhythmic drug is diltiazem?
calcium channel blocker
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what is meant by an accessory pathway causing a supraventricular tachyarrhythmia?
abnoraml connection between atria and ventricles resulting in a short PR interval
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what age are accessory pathways seen in dpgs causing a supraventricular tachyarrhythmias?
young dogs (1-2 years old)
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what is done to treat atrial fibrillation?
treat underlying cardiac disease (CHF)
accept rhythm and slow conduction through AVN - digoxin, calcium channel blockers...
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what effects does digoxin have on the heart?
negative chronotrope
weak positive inotrope
vagomimetic (slow conduction across AVN)
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what can be added with digoxin to aid treatment of atrial fibrillation?
diltiazem (better heart rate control) - calcium channel blocker
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which of the anti-arrhythmic drugs should never be used for uncontrolled congestive heart failure?
beta blockers
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what is used to assess whether a patient with ventricular tachycardia needs treatment or not?
look at patient
if haemodynamically significant
if it is multifocal
if very fast or close coupling
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what are some possible underlying causes of ventricular ectopics?
cardiac disease
catecholamines (stress, pain...)
acidosis
hyperkalaemia
thoracic trauma
drug induced
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what can be used for emergency treatment of ventricular tachyarrhythmias?
lidocaine IV
esmolol IV
amiodarone
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what can be used to treat ventricular tachyarrhythmias at home?
oral - sotalol, mexilitine, beta blockers, amiodarone
(sotalol most commonly used)
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what class anti-arrhythmic drug is sotalol?
3 (beta blocker)
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what are the possible types of bradyarrhythmias?
sinus bradycardia
sinus arrest
sinoventricular rhythm (hyperkalaemia)
1st degree AV block
2nd degree AV block
3rd degree AV block
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what are the features of a first degree AV block on ECG?
long P-R interval (often the effect of a drug or high vagal tone)
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what are the types of second degree AV block?
mobitz 1 (physiological)
mobitz 2 (pathological)
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what is a third degree AV block?
complete AV block (few ventricular waves - no association with P wave)
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why do cats cope better with third degree AV block?
tend to not be as active as dogs
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what are some possible treatment for bradyarrhythmias is the owner doesn't want a pacemaker?
treat underlying disease
anticholinergics (if vagally mediated) - atropine
beta sympathomimetics
251
what are the three main indications of measuring a patients blood pressure?
assessing severity of heart disease
identifying systemic hypertension
assessing response to drugs
252
what are the two indirect methods of recording blood pressure?
doppler
oscillometric technique
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how is the doppler technique used to assess blood pressure?
cuff inflated until flow is occluded and then gradually deflated until flow is detected in the artery again this corresponds to the arterial blood pressure
254
what is the advantage of using the oscillometric technique to measure blood pressure rather than the doppler?
can record both diastolic and systolic blood pressure
255
what are the four main systems systemic hypertension can negatively effect?
ocular, renal, cardiac, CNS
256
what are the possible ocular consequences of systemic hypertension?
hyphema, retinal detachment, retinal haemorrhage
257
what is the drugs of choice used to reduce systemic blood pressure?
amlodipine
258
what is the mode of action of amlodipine?
calcium channel agonist (limited to vascular smooth muscle)
259
what is the main change in urine of animals with systemic hypertension?
proteinuria
260
what drugs are indicated for proteinuria caused by systemic hypertension?
ACE inhibitors
261
what is the mode of action of ACE inhibitors that means they are an effective treatment for proteinuria caused systemic hypertension?
effect the efferent arteriole more than the afferent (causes dilation of both)
262
what is a commonly used ACE inhibitor?
benazepril
263
what are the three features of Virchow's triad that leads to a blood clot forming?
blood flow stasis
hyper-coagulable state
damaged endothelium
264
what is the most common site of emboli formation in cats?
left atrium due to myocardial disease (associated with marked left atrial dilation)
265
where do emboli formed in the left atrium usually embolise to?
distal aorta - feline arterial thromboembolism (FATE)
266
how do cats with feline arterial thromboembolism (FATE) present clinically?
severe acute pain and loss of hindlimb function
cold limbs with non-pigmented pads turn cyanotic
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what is the prognosis of cats with FATE?
grave (needs adequate pain control)
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what is used to treat FATE?
opiates
clopidogrel - anti-platelet
aspirin - prevents further platelet activation
269
what is the most common cause of thrombi in dogs?
endocrinopathy (hypothyroidism, hyperadrenocorticism)
270
what are some possible causes of pulmonary hypertension?
pulmonary vascular changes
Dirofilaria or Angiostrongylus
left sided CHF
pulmonary thromboembolism
271
what is the drug most commonly used to treat pulmonary hypertension?
pimobenden (sildenafil also useful)
272
how can pulmonary hypertension be diagnosed?
clinical signs
radiographs (pulmonary arterial dilation)
doppler echocardiography (tricuspid or pulmonary regurgitation)
273
how can pulmonary thromboembolism be diagnosed?
partial blood gas analysis - it creates a large ventilation:perfusion mismatch so there will be a large alveolar to arterial oxygen gradient
274
what is the brief lifecycle of Dirofilaria immitis?
L3 transmitted to dog by mosquito
larvae matire to L5 in pulmonary arteries
microfilaria released into bloodstream to effect other mosquitoes
275
what is the prepatent period of Dirofilaria immitis?
6 months
276
how can Dirofilaria immitis be diagnosed?
thoracic radiographs
heart worm antigen test
antibody test
microfilaria test
277
how is Dirofilaria immitis treated?
ivermectin or milbemycin
278
what can be used to prevent heart worm?
ivermectin, milbemycin, modidectin (monthly, orally)
selamectin (monthly, topically)
279
what is the prepatent period of Angiostrongylus vasorum?
7-9 weeks
280
what can be used to treat angiostrongylus vasorum?
milbemycin or fenbendazole
