Tom Robertson MA VetMB CertVDI CertVC MRCVS
Subjects to be covered:
 Anatomy and Function of the normal heart
 What causes a murmur and what goes wrong in heart
failure
 Congenital and acquired conditions in predisposed
breeds
 Nursing the cardiac patient
 ? Blood pressure
M
The role of the cardiovascular
system
 To provide nutrients (e.g.Oxygen)to all organs via
arteries and capillary beds.
 To remove waste products of metabolism (e.g.Carbon
dioxide) via capillaries and veins
Arteries
 The aorta carries blood to the periphery and its elastic
nature promotes flow in diastole and systole.
 The smaller arteries have muscular walls and
contraction of these alters the vascular resistance and
therefore blood pressure
Veins
 These hold 70% of the blood volume
 Contraction of the venous system increases the return
of blood to the heart, vasodilation reduces the return
to the heart.
The Heart
 Starlings Mechanism
 Systole is the period of cardiac contraction when blood
is ejected from the heart into the aorta or pulmonary
artery
 Diastole is the period of cardiac relaxation when blood
returns to the heart and fills the chambers ready for
the next contraction
 Coronary blood flow during diastole
 Taking a cardiac history - what’s important?
History
 Exercise tolerance, changes in activity/behaviour
 Breathing changes – normal resting respiratory rate is
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less than 30bpm
Syncope
Sleep habits
Alterations in appetite
Weight change
Coughing – does heart failure cause coughing?
Cardiac Cachexia – loss of muscle mass due
to heart disease. A coughing overweight dog
is more likely to have lung disease.
Clinical examination
 Observe respiration from a distance
 Mucous membranes – pale/cyanotic
 Jugular veins
 Check for precordial thrill at apex beat
 Femoral pulses
 Normal pulses 70-160 dogs, 90-240 cats
 Palpate abdomen –
ascites/hepatomegaly
auscultation
 Listen to both sides in a quiet room – heart and lungs
 Ideally palpate pulses at the same time as listening to
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the heart
Listen for murmurs/gallop sounds
Sinus arrhythmia
Heart rates of 80-120bpm in dogs suggest heart failure
is unlikely (low sympathetic drive)
Cats can do anything but slow heart rates and
hypothermia are bad signs!!
ECG
ECG
Normal ecg
Echocardiography
X-ray Quiz
Why X-Ray?
 Best way to assess overall heart size – VHS
 Only way to confirm congestive heart failure
 Identifies other thoracic pathology
 A murmur is caused by turbulent blood flow
 Caused by blood flowing the wrong way or blood
moving too quickly
 Physiological – e.g anaemia, athletic lean dogs
 Associated with structural disease e.g VSD, AS/PS
 Diastolic, systolic or continuous
 Grade 1 – difficult to hear
 Grade 2 – quieter than the normal heart sounds
 Grade 3 – same intensity as the other heart sounds
 Grade 4 – louder than the other heart sounds
 Grade 5 – precordial thrill present
 Grade 6 – audible without touching the thorax
Cardiac Cycle
Q
P
R
S
T
 Normal
 MR
 PDA
Gallop Rhythms
 The heart potentially has 4 heart sounds.
 A gallop is an extra audible heart sound resulting in a
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heart that sounds like the canter of a horse
S1 – closure of the AV valves. Start of systole.
S2 – closure of the semilunar valves
S3 – rapid filling of the ventricle during diastole
S4 – atrial contraction
 Preload – volume of blood returning to the left
ventricle and volume of blood left over after the last
contraction
 Afterload – resistance against which the left ventricle
has to eject blood
 Fluid is maintained in blood vessels via hydrostatic
and osmotic pressures
 XS fluid is removed via the lymphatic system and
returned to the heart
Heart Failure/Vascular Shock
 Heart output drops - noted by kidneys and
baroreceptors in aorta and carotids
 Activation of the renin angiotensin system to conserve
water – increased thirst and sodium retention
 Sympathetic nervous system activated to increased
heart contractility, HR, vasoconstriction
 Increased blood return to the heart causes increased
contractility
Congestive heart failure
 If pre-load increases too much the hydstatic pressures
in the capillaries increases, the lymphatics are
overwhelmed and fluid accumalates in the interstitial
areas – congestive heart failure
 Right sided failure – ascites, pericardial effusion
 Left sided failure – pulmonary oedema
Forwards failure
 Heart output is insufficient to provide enough
oxygenated blood to the head or body
 Leads to exercise intolerance and syncope
Clinical signs of heart failure in cats
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Dyspnoea (difficulty breathing)
Tachypnoea (rapid breathing)
Often get pleural effusions
Pulmonary oedema
Ascites
Cold extremities/cyanotic extremities
No cough
Embolism
May not present until very late in the course of the
disease
Clinical signs of heart failure in
dogs
 Tachycardia
 Dyspnoea/tachypnoea
 Ascites
 Cyanosis/cold extremities
 Weight loss
 ?coughing
Dilated Cardiomyopathy
Dilated cardiomyopathy
 Causes : genetic, chronic tachycardia, lack of taurine
in cats (and some dogs), hypothyroidism
Pre-clinical DCM
 Aim to diagnose at risk breeds prior to development of
signs of CHF
 Dobermans 60% affected and 25-30% can have sudden
death in the preclinical phase
 VPC’s are most common initial findings
Boxers
 Arrhymthogenic right ventricular cardiomyopathy
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(Boxer Cardiomyopathy)
Collapsing boxers
Variable progression
Holter monitor
Troponin I
Cocker Spaniels
 Some are Taurine deficient
 Better long term prognosis
 Classical DCM on echo
Hypertrophic Cardiomyopathy
HCM
 Most common heart disease in cats
 Thickening to the myocardium preventing normal
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filling and ventricular relaxation during diastole
Maine Coons
Ragdolls
British Short hairs
Sphinx
Secondry to hyperthyroidism, acromegaly, systemic
hypertension
Restrictive Cardiomyopathy
 Fibrous irregular myocardium
 Systolic failure
 Very large left and right atria
Feline aortic thromboembolism
(FATE)
 May be the first sign of heart disease
 Thrombus occurs because blood is flowing more
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slowly than normal
Normally lodges in the right brachial artery or the
aorta
Acute paralysis to one or both legs
Severe pain/distress
Hypothermia/Bradycardia poor prognostic signs
Treatment of FATE
 Analgesia – opiates
 Oxygen
 Treat heart failure
 Heparin injections
 Nutritional support
 Long term clopidogrel/aspirin as preventative
 Consider euthanasia in severe cases
Pericardial effusion
Pericardial effusion
 Fluid around the heart occurs due to:
Neoplasia, idiopathic, heart failure, infection
 Causes right sided failure due to cardiac tamponade
 Right sided failure develops: ascites, jugular venous
distension.
 NB do not use diuresis as reduces blood pressure and
worsens the tamponade
Treatment of pericardial effusion
 Pericardiocentesis
Myxomatous Mitral Valve Disease
 Most common acquired heart disease in dogs
 Small breeds
 CKCS
 Slowly progressive disease
Myxomatous Mitral Valve Disease
MMVD
Oh no its an ECG!!
Oh crap another one!
Last one I promise!
Tricuspid Dysplasia
Tricuspid dysplasia
PDA
 Has been reported as most common defect
 Failure of closure of the Ductus Arteriosus at birth
 Continuous murmur
 Females:males
 Toy Breeds -Maltese, Pomeranians, Yorkies, Bichon
Frise
 Border Collies
 English Springer Spaniels
 GSD’s
PDA treatment
 Surgery
 Amplatz Canine Duct Occluder
 2.5k-3k cost
PDA surgery
 http://www.youtube.com/watch?v=F1BDn6nFCII&list
=UU1VXxdm_MDPqvjOa8mMgXqw
Aortic Stenosis
 Abnormal narrowing to aorta
 Boxers (Breed Scheme)
 Golden Retrievers
 German short haired pointer
 Rottweiler
 GSD
 Newfoundlands
 Graded according to blood velocity
 Medical treatment only
Pulmonic Stenosis
 Cocker Spaniels, Boxer, Bulldogs, Beagle, Chihuahua
 Abnormal narrowing to pulmonary artery
 Severe stenosis treatment with balloon valvulplasty
http://www.youtube.com/watc
h?v=0N7V7SQ7API&list=UU1VX
xdm_MDPqvjOa8mMgXqw
Ventricular Septal Defect
 English Springer Spaniels
 English Bulldog
Are all murmurs in puppies/kitten
bad?
 Innocent murmurs common <4months
 <grade 3
 Should disappear by 4m in dogs
 No clinical signs
 Can continue into adulthood in cats
Emergency Treatment
 Oxygen
 Minimal Stress
 2mg/kg frusemide IV/IM every 2 hours
 Monitor urine output
 Free access to water
 Maintain correct temperature
 Monitor RR, HR every 2 hours
 Abdominocentesis
 Thoracocentesis
Long term treatment
 Moderate sodium restriction in diet
 Good quality food
 Omega oil supplements – protect against
muscle loss
 Monitor RR and HR – CEVA App
 Weight checks – beware cardiac cachexia
 Monitor electrolytes/renal function
What do all those drugs do??
 Improve contractility - pimobendan
 Reduce fluid overload - frusemide
 Dilate blood vessel – ace-inhibitors/pimobendan
 Reduce fibrosis to myocardium - spironolactone
 Normal blood pressure in dogs/cats 60-150
 Hypetensive >170mmHg dogs, >180mmHg cats
 Increased blood pressure (hypertension) can affected
the eyes (retinal bleed/detachment), CNS,kidneys and
heart
 Symptoms include blindness, dilated pupils, protein
loss in the kidneys, heart murmurs.
Causes of hypertension
 Hyperthyroidism
 Kidney disease
 Diabetes
 Cushings
 Primary
 Measurement:direct vs indirect
 Oscillometric
 Used on the tail or leg
 Detects oscillations in blood vessels
 Doppler
 Treatment of high blood pressure: amlodipine
Blood pressure
 Most normal cats have systolic pressure 130-175mmHg
 175-200mmHg is suspicious of hypertension
 >200mmHg likely genuine hypertensive
Doppler
 Quiet room
 Cuff between carpus and elbow width 40% of limb
circumference
 Spirit over common digital artery then gel
 Apply probe over the common digital artery and listen
for pulse (use head phones)
 Inflate cuff until sound goes then gradually deflate
until pulse audible again
Hypotension
 Readings of <90mmHg are consistent with
hypotension
 Blood pressure should be maintained above 60mmHg
to ensure adequate tissue perfusion to vital organs