Cardiology Flashcards
ASD - atrial septal defect
Usually quiet to moderate
Base L and R
Systolic
R side eccentric hypertrophy if severe
Can be incidental - non significant
VSD - ventricular septal defect
Variable/diagonal grade
Base L, Apex R
Systolic
L side volume load - eccentric hypertrophy
Small lesion - often loud murmur - tolerated well
Exercise intolerance
LCHF
AS - aortic stenosis
Variable, loud if severe
Base L > R
Systolic
LV concentric hypertrophy
If severe, pulses poor, murmur audible in carotid arteries
SAS might get worse until adult - assess at 1 year
Narrowing of aorta
3 types - sub-aortic stenosis, valvular aortic stenosis, supravalvular
Lethargy, exertional weakness, syncope, sudden death (1/3 of cases)
PS - pulmonic stenosis
Variable, loud if severe
Base L > R
Systolic
RV hypertrophy
5 types
Infundibular
Sub-valvular pulmonic stenosis (uncommon)
Valvular pulmonic stenosis (common) can be leaflets themselves or annulus of valve
Supra-valvular (rare)
Anomalous coronary artery
Usually smaller breed dogs
Asymptomatic on presentation
Right sided heart failure, syncope, exercise intolerance
Sudden death
Prominant right apical beat
PMI left heart base
Radiates cranially ventrally
Prominent jugular pulses
MV dysplasia
Mitral valve dysplasia (L AV valve)
Variable
Apex L
Systolic, may have MS too - diastolic
L side volume load - eccentric hypertrophy
TV dysplasia
Tricuspid valve dysplasia - R AV valve
Variable
Apex R
Systolic
R side volume load - eccentric hypertrophy
PDA - patent ductus arteriosus
Usually loud
Base and apex
Continuous
L side volume load - eccentric hypertrophy
Continuous murmur
Blood shunting from aorta to pulmonary artery
Continuous murmur
Left heart base very cranial and dorsal - axilla
Should close within hours of birth - within days to weeks
Will cause volume overload of pulmonary circulation and LA and LV
Will progress to left sided congestive heart failure in 12 months
T of F - tetralogy of fallot
Variable
Base usually
Systolic
RV hypertrophy
Cyanosis
When is a murmur innocent vs CHD
Low grade is innocent
PMI of left heart base is innocent
Timing mid systolic is innocent
Variable with heart intensity - innocent
Resolution by 6 months usually - innocent
How does oxygen get to haemoglobin
Oxygen in inhaled gas
Chest function
Airways
Lungs
Arterial blood
Haemoglobin
Causes of cyanosis
No oxygen - altitude, supply failure
Cannot get oxygen to lungs
- Chest damage
- Muscle damage
- URT obstruction
- Pleural space disease
Cannot get oxygen into blood
- Interstitial lung disease
- Diffuse alveolar disease
Reduced systemic oxygen
- R to L shunting
- Tetralogy of Fallot
- Eisenmenger’s physiology
Oxygen cannot bind to Hb
- Haemoglobinopathy
- Methaemoglobinaemia
Causes of cyanosis
No oxygen - altitude, supply failure
Cannot get oxygen to lungs
- Chest damage
- Muscle damage
- URT obstruction
- Pleural space disease
Cannot get oxygen into blood
- Interstitial lung disease
- Diffuse alveolar disease
Reduced systemic oxygen
- R to L shunting
- Tetralogy of Fallot
- Eisenmenger’s physiology
Oxygen cannot bind to Hb
- Haemoglobinopathy
- Methaemoglobinaemia
Myocardial diseases
Primary
Secondary
Primary myocardial disease
1. Dilated cardiomyopathy (DCM)
Heart is stretched - no extra cells
- Arrhythmogenic right ventricular cardiomyopathy (ARVC)
Very specific to boxers - Hypertrophic cardiomyopathy (common in cats)
Thicker heart muscle - more cells added - Restrictive cardiomyopathy (common in cats)
Heart gets fibrotic - not able to pump as effectively
Secondary myocardial disease
1. Infective myocarditis
Hard to prove that it’s infectious (could be inflammation, etc.)
- Deficiency diseases
Taurine amino acid - Toxic causes - doxorubicin
DCM - dilated cardiomyopathy
Most common form in dog, rare in cat
Impaired myocardial contractility with dilation of LV +- RV
Tachyarryhthmias are common - supraventricular and or ventricular
DCM is end stage of many diseases so priamry is diagnosis of exclusion
Eccentric hypertrophy of the LV
*Bigger chambers
Systolic failure
* ‘Forward failure’ - not enough blood is getting into the body
* Lost contractility
Diastolic failure
* ‘Backward failure’ – congestion
* Blood still stuck in the large chambers
LA dilation and increased LAP
*Right side can also be affected
Usually middle aged dogs, >12kg, males more seriously affected
Loss of systolic function results in low CO
Low CO results in forward failure - systolic
Compensatory mechanisms - maintain CO by increasing HR, peripheral vasoconstriction, volume expansion
Ventricle fails to empty - increased ventricular diastolic pressure
Compromised coronary perfusion - worsening myocardial function - arrhythmias
Two phases of DCM
* Occult phase (can last weeks-years)
- Symptomatic phase
- Usually CHF
- Syncope
- Weight loss
- Sudden death – much more likely than with valve disease
- Soft murmur - due to regurgitation of blood into left atrium rather than valve itself
- Atrial fibrillation
- Onset of clinical signs can be sudden
- Signs of forward output failure – weakness, lethargy, syncope, exercise intolerance (more common)
- Dyspnoea
- LCHF causing oedema
- Cough
- Heart enlargement pressing on trachea and oedema
- Anorexia
- Ascites if R side affected
- Cardiac cachexia – profound weight loss
- Tachycardia +/- arrhythmias – AF, VPCs (large ventricles), VT* Compensation due to lack of blood flow round the body* Variable pulses +/- pulse deficits IF dysrhythmic* Vasoconstriction compensation* Signs of LCHF +/- RCHF * Gallop sounds – IF in sinus rhythm* Heart enlargement* Soft MR / TR murmurs* If forward failure (often bad news)* Pale mucous membranes* Sluggish CRT* Cool extremities
On echo
Typical findings* Large, round, poorly contractile LV* Poor systolic function (poor contractility)* Dilated, round LA* +/- MR small/moderate due to annulus dilation* +/- right sided changes
Treatment
Treat the LCHF
Treat arrhythmias
Arrhythmogenic right ventricular cardiomyopathy
Primarily boxers
Myofibre atrophy, fibrosis and fatty infiltration
3 stages of disease
1. Asymptomatic with ventricular arrhythmias
Fibrotic heart doesn’t pump properly
- Symptomatic – normal heart size and LV function but dogs are syncopal/weak from ventricular arrhythmias
- CHF – poor myocardial function, CHF and ventricular arrhythmias
- Can appear any age - mean age 8yrs
- Ventricular arrhythmias
*Supra-ventricular arrhythmias - > 500 VPCs / 24hrs
*Holter monitor at home to gain knowledge of extent - But spontaneous variation of up to 80%
- Syncope
- Sudden death
Diagnosis
24h Holter monitor
Refer
ECG and echo
Treat LCHF
Sotalol
