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41 Cards in this Set

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Valvular endocardiosis

Myxomatous degeneration of the heart valves, affecting mitral and tricuspid valves, leading to their incompetence

Breed and sex predisposition

CKC spaniel, poodles, males

Clinical signs

Systolic murmur over mitral and tricuspid valves.



Starts off as low grade left apical systolic murmur but grade increases, as does duration to become pan systolic




Mitral murmur moves over to right side of heart




Coughing due to large left atrium pressing on bronchi




Exercise intolerance




May present with incidental murmur or left sided or biventricular heart failure

Radiography

Left atrial and ventricular enlargement




Severe mitral insufficiency




Right atrial and ventricular enlargement




Severe tricuspid insufficiency




Check pulmonary veins and lung fields for congestion or oedema




Generalised cardiomegaly

Electrocardiography

P waves - wide - left atrial enlargement or - wide and tall - left and right atrial enlargement




R waves - frequently tall and wide due to left ventricular enlargement




Tall R waves, wide QRS and deep Q wave indicative of biventricular enlargement




May be sinus tachycardia

Echocardiography

Thickened valves may be visualised




Chamber enlargement




Doppler ultrasound

Treatment

Depends on class of failure:




Frusemide, ACE inhibitors, pimobendan




Additional diuretics may be needed or digoxin for sinus tachycardia or atrial fibrillation



Prognosis

Guarded once heart failure develops

Cause of bacterial endocarditis

Systemic bacteraemia - septic emboli will seed off

PATHOphysiology

Valvular incompetence or stenosis

Valve affected in cows compared to dogs and cats

tricuspid - emboli to lungs




D and c - emboli to joints and kidneys

source of bacteria for dogs

often periodontal disease

Presenting signs

Variable:




Lameness




Lethargy




Fever




Haematuria




Dyspnoea

Clinical findings

Pyrexia most common




Shifting lameness if septic arthritis




New murmur - systolic or diastolic

Radiography

Non-specific findings

Electrocardiography

Non-specific findings




Myocardial emboli or myocarditis may cause arrhythmias

Echocardiography

Vegetative lesions may be seen




Valvular lesions may lead to insufficiency/stenosis which will be apparent with Doppler

Diagnostic tests

Haematology for positive bacterial infection via culture




3 samples in 24 hours




May do urine sample and culture

Treatment

Antibiotics for 4-6 weeks




Often parenteral followed by oral

Prognosis

Guarded

Approach to patients with left-sided congestive heart failure

If stable - definitively diagnose and treat underlying cause




If critical - make stable by: oxygenation, cage rest, sedation if necessary, preload and after load reduction




then make definitive diagnosis





Approach to patients with right-sided congestive heart failure

If stable obtain definitve diagnosis




If large pleural effusion -> thoracocentesis




Abdominocentesis usually left only for diagnosis unless interfering with ventilation (because you will deprive animal of protein)




Once stable find definitive diagnosis and treat accordingly

Principles of long term treatment

Treat primary underlying cause




Preload and after load reduction


Positive inotrope


Improve diastolic filling


Correct rhythm - brady/tachyarrhythmias

Preload definition

Volume of blood filling ventricles at end of diastole

Afterload definition

Pressure left ventricle must overcome to circulate blood

Preload reduction methods

Loop diuretics




Thiazide diuretics




Potassium-sparing diuretics




ACE inhibitors




Vasodilators

Loop diuretics

Frusemide - diruetic and natriuresis




May cause dehydration, pre-renal azotaemia, hypokalaemia and hyponatraemia and may stimulate RAAS




IV frusemide is vasodilatory so can be used to decrease preload in this way

Thiazide diuretics

Hydrochlorthiazide, chlorthiazide




Diuretic and natriuresis - sodium depletion if used with loop diuretic

Potassium-saring diuretic

Spironolactone - spares potassium, slow acting and cannot be used on its own but with ACE inhibitors and other diuretics

Venodilators (rhea)

Glyceryl trinitate -useful for cardiogenic pulmonary oedema - absorbed through skin - short term




Frusemide IV

ACE inhibitors (pril)

Enalapril, benazepril, imidipril, ramipril -




Hyperkalaemia is possible (careful with potassium sparing diuretics and potassium supplementation)




Enalapril - renal excretion so

Afterload reduction

Arteriodilators




ACE inhibitors




Inodilators

Arteriodilators

Hydralazine - mitral valve insufficiency,




May cause hypotension and reflex tachycardia




Large tablet hard to administer in small dogs and cats

Inodilators

Pimobendan - positive inotrope, vasodilator, no compensatory tachycardia

Treating systolic failure

Calcium sensitizer/inodilators




Cardiac glycosides




Beta agonist

Calcium sensitizer/inodilator

Pimobendan - beneficial for dilated cardiomyopathy and myxomatous valve disease

Cardiac glycoside

Digoxin




Weakly positive inotrope and used to control ventricular rate in ventricular fibrillation




Maintenance dose




Stop use if: anorexia, nausea, GI signs, arrhythmias




Decrease for obese dogs, fluid retention, dobermans, renal failure




Long half life in cats so use with caution

Beta agonist

Dobutamine




IV, severe myocardial failure

Treating diastolic failure

Depends on underlying cause




Drain pericardial effusion




Improve ventricular relaxation




Slow heart rate and thus increase filling time




Decrease contractility and thus myocardial O2 consumption

Calcium channel antagonists

Diltiazem - lusitropic, negative inotrope and chronotrope

Beta blocker

Propanolol




Reduce heart rate so increase filling time and cardiac work




Negative inotrope