Cardiovascular Disease Flashcards
What are the normal heart rates for dogs and cats?
Dogs = 60-180bpm Cats = 120-240bpm
What are the main types of cardiac diseases we can check for?
Congenital cardiac disease
Acquired heart diseases
Arrhythmias
Give examples of congenital cardiac disease.
Abnormalities of heart development in utero e.g. Aortic stenosis Pulmonic stenosis Patent Ductus Arteriosus Ventricular septal defect
Give examples of acquired heart diseases in dogs and cats.
Dogs = myxomatous mitral valve disease / dilated cardiomyopathy / pericardial effusion Cats = hypertrophic cardiomyopathy
How can we diagnose heart disease?
History Physical examination Blood tests Blood pressure Electrocardiography (ECG) Echocardiography Thoracic radiographs
What typical presentations in the history lead us to consider heart disease?
Incidental finding - heart murmur/arrhythmia
Exercise intolerance, weakness, syncopal (fainting) episodes
Heart failure (left-sided = difficulty breathing (tachypnoea/dyspnoea) / right-sided = difficulty breathing and/or distended abdomen)
Sudden death
What are we looking for on physical examination?
Loss of body condition MMs - colour/CRT Jugular veins - visible/pulsation Peripheral pulses - quality/regular/deficits Respiratory rate - > 35-40 breaths/min Heart auscultation Lung auscultation
What are we assessing on auscultation of the heart?
Heart rate
Rhythm - regular/irregular, gallop sounds
Pulse - quality/deficits
Heart murmurs - timing/point of maximal intensity/grading
What are we assessing on auscultation of the lungs?
Respiratory rate
Adventitious sounds
Crackles
What are the typical findings in heart failure?
Reduced cardiac output - weak peripheral pulses, tachycardia, pale MMs, prolonged CRT Weakness, exercise intolerance, syncope Heart murmur Gallop sounds Arrhythmias +/- pulse deficits Congestion
Describe left- and right-sided congestion.
Left-sided = lungs (pulmonary oedema, tachypnoea (> 40 breaths/min), dyspnoea) Right-sided = systemic (distended peripheral veins, ascites (free fluid in abdomen), pleural effusion)
What blood tests can we carry out?
Haematology (systemic diseases, anaemia)
Biochemistry (kidney values, electrolytes)
Cardiac biomarkers - cardiac troponin I (cTnI) / N-terminal pro-B-type natriuretic peptide (NT-proBNP)
What is normal systolic blood pressure?
120-140mmHg
Consider effects of stress
How do hypertension and hypotension indicate heart disease?
Hypertension = increased cardiac workload, can contribute to progression of disease Hypotension = might indicate decompensated heart failure, < 80mmHg is concerning
How do we use electrocardiography (ECG) to diagnose heart disease?
Further characterise auscultatory findings: Bradycardia Tachycardia Irregular rhythm Pulse deficits
How can we use a Holter monitor (24hr ECG)?
To investigate intermittent arrhythmias
Clinical importance of arrhythmia - suspected cause of syncope/exercise intolerance, frequency + severity at home
Response to antiarrhythmic therapy
How do we use echocardiography (cardiac ultrasound)?
Diagnose cardiac disease Treatment options Severity of disease and prognosis Progression of disease Response to treatment
What are the indications for thoracic radiographs?
Cough
Dyspnoea
Tachypnoea
What views do we use for thoracic radiographs investigating heart disease?
At least two views
Right lateral
Dorsoventral
What are we looking for on thoracic radiographs?
Congestive heart failure
Lung pathology
Cardiomegaly
Where may the narrowing of the vessels in stenosis occur?
Subvalvular (below valve)
Valvular
Supravalvular (above valve)
Describe aortic stenosis.
Subvalvular
Left ventricular hypertrophy (increased workload)
Left-sided congestive heart failure
Describe pulmonic stenosis.
Valvular
Right ventricular hypertrophy (increased workload)
Right-sided congestive heart failure
What clinical signs do we see of stenosis?
Can be asymptomatic Arrhythmias Exercise intolerance Syncope Congestive heart failure
How do we treat stenosis?
Beta blocker
Balloon valvuloplasty (pulmonic stenosis)
Standard treatment for congestive heart failure
What happens if fetal ductus arteriosus remains patent?
Blood flow from aorta to pulmonary artery
Loud continuous murmur at left heart base
Incidental finding / congestive heart failure
How do we treat patent ductus arteriosus?
Interventional closure (ductal occluder)
Surgical ligation
Congestive heart failure therapy
Describe a ventricular septal defect.
Most common location = upper septum (just below aortic valve)
Usually asymptomatic
Right-sided systolic murmur (small defect = loud murmur, large defect = soft murmur)
Usually no treatment necessary / heart failure treatment
Normal life expectancy if small defect
Describe myxomatous mitral valve disease.
Idiopathic - hereditary
Small breed dogs e.g. Cavalier King Charles spaniels, Dachshunds etc.
Adult onset
Mitral / tricuspid valve
Left-sided apical systolic heart murmur
Slow progression (long asymptomatic period, incidental finding)
May progress to left-sided congestive heart failure
How do we diagnose myxomatous mitral valve disease and what are we looking for?
Echocardiography
Thickening of valve leaflets - regurgitation of blood, left atrial dilation, left ventricular dilation
Prolapse of valve leaflets
Describe dilated cardiomyopathy.
Idiopathic - hereditary
Large breed dogs - Dobermann, Great Dane, Newfoundland
Adult onset
Left apical systolic murmur (not always present)
Long asymptomatic period
What does dilated cardiomyopathy cause and how does it progress?
Disease of myocardium - left ventricular dilation, decreased systolic function, arrhythmias
Progression may be rapid - arrhythmias, sudden death, congestive heart failure
Describe pericardial effusion.
Large breed, adult dogs
Causes = idiopathic, neoplasia, etc.
Fluid in sac around heart compromises filling (‘tamponade’) - decreased cardiac output, right-sided heart failure
How do we treat pericardial effusion?
Pericardiocentesis (drainage): Mild sedation, left lateral recumbency Prepare area 3rd-8th intercostal space Large catheter Visualise window (echocardiography)
How do we differentiate between blood and pericardial fluid?
Check for clotting (should not clot like blood)
Check PCV of fluid (lower than blood)
Measure volume drained
Collect samples (cytology = EDTA, culture = sterile tubes)
Describe hypertrophic cardiomyopathy.
Most common cardiac disease in cats
Genetic causes, adult onset
Exclude other causes of hypertrophy (hyperthyroidism, systemic hypertension)
Increased myocardial thickness impairs filling in diastole
How can hypertrophic cardiomyopathy present?
(Right-sided) heart failure - pulmonary oedema, pleural effusion
Incidental finding - heart murmur, gallop sound
Aortic thromboembolism - sudden onset lameness, cold leg, peripheral cyanosis, pain
What can heart failure be due to?
Disease progression
Decompensation of previously stable heart failure
Development of impedance of cardiac filling, e.g. pericardial effusion
What do both left- and right-sided heart failure lead to?
Decreased cardiac output
Tachycardia
Weak peripheral pulses
Slow CRT
How do cats differ when presenting with heart failure?
Cats may present with hypothermia and bradycardia.
How do we treat heart failure?
Furosemide (diuretic - decrease circulating volume)
Minimise stress
Oxygen
Pimobendane (increases contractility - dogs)
ACE inhibitor (vasodilator, anti-remodelling)
Spironolactone (weak diuretic, anti-remodelling)
Water must always be available
What are the signs of improvement in heart failure patients?
Decreased respiratory rate and effort
Decreased heart rate
Improved pulse quality
Improved CRT
Give some examples of causes of bradycardia.
Sinus bradycardia
Atrial standstill
Atrioventricular blocks
Sick sinus syndrome
Describe the 3 stages of AV block.
1st degree = slow conduction through AV node (longer gap between P and QRS)
2nd degree = non-conducted P waves (some P waves not followed by QRS)
3rd degree = atrial rate 200bpm, ventricular rate 40bpm (wide and bizarre QRS complexes)
Describe supraventricular tachycardia.
Originate from the atria
QRS complexes are narrow (similar to sinus complexes)
What is an example of supraventricular tachycardia?
Atrial fibrillation - heart rate 210bpm, irregular rhythm, no P waves
Describe ventricular arrhythmia.
Originate from the ventricular myocardium
QRS complexes are wide and bizarre
Ventricular tachycardia - heart rate 375bpm
