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
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M
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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
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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
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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.
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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
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Taking a cardiac history - whats important?
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History Exercise tolerance, changes in activity/behaviour
Breathing changes normal resting respiratory rate is less than
30bpm Syncope Sleep habits Alterations in appetite Weight change
Coughing does heart failure cause coughing?
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Cardiac Cachexia loss of muscle mass due to heart disease. A
coughing overweight dog is more likely to have lung disease.
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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
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auscultation Listen to both sides in a quiet room heart and
lungs Ideally palpate pulses at the same time as listening to 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!!
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ECG
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Normal ecg
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Echocardiography
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X-ray Quiz
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Why X-Ray? Best way to assess overall heart size VHS Only way
to confirm congestive heart failure Identifies other thoracic
pathology
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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
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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
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Cardiac Cycle P Q R S T
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Normal MR PDA
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Gallop Rhythms The heart potentially has 4 heart sounds. A
gallop is an extra audible heart sound resulting in a 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
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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
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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
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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
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Forwards failure Heart output is insufficient to provide enough
oxygenated blood to the head or body Leads to exercise intolerance
and syncope
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Clinical signs of heart failure in cats 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
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Clinical signs of heart failure in dogs Tachycardia
Dyspnoea/tachypnoea Ascites Cyanosis/cold extremities Weight loss
?coughing
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Dilated Cardiomyopathy
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Dilated cardiomyopathy Causes : genetic, chronic tachycardia,
lack of taurine in cats (and some dogs), hypothyroidism
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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 VPCs are most common
initial findings
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Boxers Arrhymthogenic right ventricular cardiomyopathy (Boxer
Cardiomyopathy) Collapsing boxers Variable progression Holter
monitor Troponin I
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Cocker Spaniels Some are Taurine deficient Better long term
prognosis Classical DCM on echo
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Hypertrophic Cardiomyopathy
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HCM Most common heart disease in cats Thickening to the
myocardium preventing normal filling and ventricular relaxation
during diastole Maine Coons Ragdolls British Short hairs Sphinx
Secondry to hyperthyroidism, acromegaly, systemic hypertension
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Restrictive Cardiomyopathy Fibrous irregular myocardium
Systolic failure Very large left and right atria
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Feline aortic thromboembolism (FATE) May be the first sign of
heart disease Thrombus occurs because blood is flowing more 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
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Treatment of FATE Analgesia opiates Oxygen Treat heart failure
Heparin injections Nutritional support Long term
clopidogrel/aspirin as preventative Consider euthanasia in severe
cases
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Pericardial effusion
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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
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Treatment of pericardial effusion Pericardiocentesis
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Myxomatous Mitral Valve Disease Most common acquired heart
disease in dogs Small breeds CKCS Slowly progressive disease
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Myxomatous Mitral Valve Disease
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MMVD
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Oh no its an ECG!!
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Oh crap another one!
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Last one I promise!
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Tricuspid Dysplasia
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Tricuspid dysplasia
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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 GSDs
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PDA treatment Surgery Amplatz Canine Duct Occluder 2.5k-3k
cost
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PDA surgery http://www.youtube.com/watch?v=F1BDn6nFCII&list
=UU1VXxdm_MDPqvjOa8mMgXqw
http://www.youtube.com/watch?v=F1BDn6nFCII&list
=UU1VXxdm_MDPqvjOa8mMgXqw
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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
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Pulmonic Stenosis Cocker Spaniels, Boxer, Bulldogs, Beagle,
Chihuahua Abnormal narrowing to pulmonary artery Severe stenosis
treatment with balloon valvulplasty
Ventricular Septal Defect English Springer Spaniels English
Bulldog
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Are all murmurs in puppies/kitten bad? Innocent murmurs
common
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.
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Causes of hypertension Hyperthyroidism Kidney disease Diabetes
Cushings Primary
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Measurement:direct vs indirect Oscillometric Used on the tail
or leg Detects oscillations in blood vessels Doppler Treatment of
high blood pressure: amlodipine
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Blood pressure Most normal cats have systolic pressure
130-175mmHg 175-200mmHg is suspicious of hypertension >200mmHg
likely genuine hypertensive
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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