small animal cardio Flashcards
what is endocardiosis?
explain the pathophys
screwed up mitral valve
- with a bad mitral valve, extra fluid flows backward into the LA, increasing your pre-load.
- this decreases your CO and decreases the amount of blood going to the rest of the body.
- body interprets this as hypovolemia and turns on RAAS
- RAAS increases water retention an increases the flow to lungs and heart
- this overloads the LA
which valves are pre-disposed to endocarditis?
the L-heart: aortic and mitral valves
volume overload leads to what kind of hypertrophy
what kind of issues do you see this with?
VOLUME = ECCentric hypertrophy
seen with VALVULAR issues like mitral regurge
walls get stretched
pressure overload leads to what kind of hypertrophy?
what kind of issues do you see this with?
PRESSURE = CONcentric hypertrophy
seen with aortic and pulmonic STENOSIS
walls get thick
what medications treat mitral valve disease?
furosemide (lasix) - diuretic
- decreases preload, decreases work on the heart
enalapril (ace inhibitor)
- decreases aferload by decreasing blood pressure
difference between dogs and cats when it comes to showing signs of congestive heart failure?
dogs get pulmonary edema - fluid actually in lung tissue - in alveolar beds
cats get pleural effusion (fluid in between the lung itself and the pleura - the membrane covering the lungs)
clinical signs of congestive heart failure
- pulmonary edema (dog) or pleural effusion (cat)
- tachypnea or hypernea
- syncope
- coughing
- rads: mainstem bronchi compression (large pulmonary vessels); alveolar pattern (air bronchograms)
- bounding pulse
what are two diseases with bounding pulses?
- PDA
2. bacterial endocarditis
what causes increased venous pressure (which leads to jugular pulses)?
R-sided heart failure caused by tricuspid valve disease
emergency therapy for congestive heart failure
- furosemide (diuretic to decrease preload)
- anxyiolytics (opioids, diazepam, ace)
- arteriodilators (decrease afterload): enalapril (ace inhibitor); amlodipine (Ca channel blocker acts on vasculature)
- pimobendan (increases contractility)
chronic therapy for congestive heart failure
- diuretics = furosemide (for pulmonary edema)
- Ace-inhibiotr = enalapril (decrease afterload)
- vasodilator & Ca channel blocker = amlodipine (decrease BP)
- positive iontrope = pimobendan (increases contractility and dilates vessels)
- beta blockers = for arrhythmias
- Ca-channel blockers = diltiazem (slows HR)
bacterial endocarditis
usually mitral or aortic valves
- often staph/strep/E.coli or bartonella
- signalment: young, often large breed dog with sudden murmur after being sick
- CS: fever, polyarthritis, hyperkinetic or bounding pulses
- tx: abx IV for at least a week: ampicillin, baytril, azitrhomycin if its bartonella
what large breed dog is susceptible to DCM?
dobies! and danes
when cocker spaniels get DCM, it is often caused by a deficiency in what?
L-cartinine
explain the pathophys of DCM
- heart muscle isn’t working right (poor/loss of contractility)
- decreased CO
- causes sympathetic activation (RAAS, hormonal, etc)
- atrial fibrillation and VPCs are common sequelae bc conduction fibers are being pulled apart
- end up with both forward and backward failure
CS of DCM
- first sign can be sudden death
- TALL “R” WAVES!!
- ventricular arrhythmias
- weakness, tachypnea, exercise intolerance, ascites, syncope
how do you treat DCM?
- positive iontrope = pimobendan (increase contractility) AND digoxin (increases contractility and slows AV node conduction)
- Ace-inhibitor = Enalapril (decrease afterload to increase circulation)
+/- - Ca channel blocker = diltiazem (slow HR; centrally acting)
- beta blocker = sotalol (good for arrhythmias)
heartworm disease complications (other stuff it causes)
- leads to R-sided CHF
- cor pulmonale (heart disease caused by primary lung disease. pulmonary hypertension increases cardiac afterload and leads to R-sided hypertrophy)
- chronic inflammatory disease –> glomerulonephritis
what is the infective stage of heartworm?
L3
heartworm tests for dogs vs cats
the test looks for FEMALE antigen
cats can have single sex infections; so cats should have ANTIGEN tests
dogs should have Ab tests
cats = antigen dogs = antibody
treatment for HWD
doxycycline for wolbachia
melarsomine/immiticide
2 month protocol: doxy for 1 month, injection of adulticide; wait one month; then have the 2nd injection; repeat HW test 6 months post treatment
HW prevention
ivermectin
what diseases can cause systemic arterial hypertension? (8)
- CKD
- cushings
- hyperthyroidism
- pheochromocytoma
- diabetes
- liver dz
- hyperaldosteronism
- intracranial lesions
what are some clinical signs or evidence of systemic hypertension (4 main things)
- progression of chronic kidney disease
- eyes: retinopathy, acute blindness
- brain: encephalopathy or stroke
- heart and vessels: left ventricular hypertrophy
how do you treat systemic hypertension
- Ca channel blockers: amlodipine and diltiazem
- Ace inhibitors - enalapril
- beta blockers - atenolol, propranolol
what are some things that cause pulmonary hypertension (4 things)
- increased pulmonary blood flow
- increased blood viscosity (polycythemia)
- increased pulmonary vascular resistance
- luminal narrowing
how do you treat pulmonary hypertension?
sildenafil (viagra!)
tadalifil (cialis)
what breed of dog is susceptible to mitral valve dysplasia?
bull terriers
what breed is susceptible to sub-aortic stenosis?
newfoundlands and goldens
what does the murmur of a sub-aortic stenosis sound like?
systolic crescendo/decresendo murmur that is loudest over left heartbase
explain the pathophys of sub-aortic stenosis
- there is an outflow tract obstruction
- causes a pressure overload in the Left ventricle
- leads to a CONcentric hypertrophy
- poor ventricular filling and coronary perfusion leads to a lack of oxygen for the heart
- mycardiocytes die
- leading to arrhythmias
- causes a secondary mitral regurgitation
- eventually leads to low output failure which can result in death
clinical signs & diagnosis of sub-aortic stenosis
- rads show big LV
2. echo shoes CONcentric hypertrophy (from pressure overload)
treatment of sub-aortic stenosis
beta-blockers! causes relaxation and decreases afterload and arrhythmias
prognosis for sub-aortic stenosis
hint: what does this disease predispose dogs to?
px not good; 50% die suddenly
predisposes to infective endocarditis!!
what breed is predisposed to pulmonic stenosis?
bulldogs! and boxers
what is the pathophys of pulmonic stenosis?
it’s basically the same as sub-aortic stenosis but on the right side of the heart.
there is some obstruction that causes a pressure overload (CONCENTRIC hypertrophy) which leads to a Right ventricular hypertrophy with secondary dilation and right atrial enlargement.
given the pathophys of pulmonic stenosis, what is an unusual clinical sign of this disease?
the murmur is best heard over the LEFT heartbase (systolic crescendo/decresendo) despite the disease being a R-sided heart disease
(sounds very similar to sub-aortic stenosis)
how do you treat pulmonic stenosis?
balloon vulvuoplasty most common!
- causes pulmonic insufficiency, but that is better to have than stenosis
explain the pathophys of a PDA (patent ductus arteriosus)?
it is a shunt connecting the aorta (L-side) and pulmonary artery (R-side).
- blood is continuously pumped thru this patency in the aorta (L-side) to the pulmonary artery (R-side)
- this leads to overload of L atria, increases pressure on the right
- this will eventually reverse the shunt
what does PDA cause?
volume overload of pulmonary vasculature
overload in LA and LV
what breeds are predisposed to PDA?
female maltese!!!
what does a PDA murmur sound like?
continuous left basilar murmur
how do you diagnose a PDA?
enlarged LA and LV
ductus bump on rads
how do you treat a PDA?
- transcatheter (coils, amplatz ductual occluder)
2. surgical ligation (cylindrical vs funnel shaped)
what is an odd sign of a reversed PDA?
after it reverses, if the shunt is located after the branches that go to the head, you get oxygenated blood going to the head and mixed blood going to the caudal party - leads to a blue butt!
who is predisposed to VSDs?
CATS!
what does the murmur of a VSD sound like?
systolic plateau murmur that is loudest on the RIGHT side
clinical signs of VSD?
holosystolic murmur heard best on the right side
creates functional pulmonic stenosis bc you are pushing more blood thru the valve.
how do you treat a VSD?
Ca Channel blocker - amlodipine: decreases afterload and decreases pressure in aorta so that there is an increase in forward flow
what is a type of atrial septic defect we see and what species does it occur more often in?
fossa ovalis
dogs
what are some signs of a severe atrial septal defect?
RA or RV enlargement due to volume overload (an ECCENTRIC hypertrophy)
what breed do we see mitral valve dysplasia in?
bull terriers - males
what is the pathophys of mitral valve dysplasia?
congenital disease in which you have dysplastic chordae tendoninae so the valves dont grow correctly.
what are clinical signs and tx of mitral valve dysplasia?
similar to degenerative valve disease but we are seeing htem in YOUNG dogs.
- regurgitation and stenosis
tx: valve replacement
what breed is predisposed to tricuspid dysplasia?
male golden retrievers - super young little babies
pathophys of tricuspid dysplasia
the tricuspid is dysplastic - it comes from the right atrium and leads to R-heart enlargement
px of tricuspid dysplasia
guarded to poor
what breed is predisposed to tetralogy of fallot?
keeshonds!!
what are the magical 4 things that make up tetralogy of fallot?
- VSD
- pulmonary stenosis
- overriding aorta (dextropositioned)*
- R-ventricular hypertrophy
what does the murmur of tetralogy of fallot sound like?
what are the CS?
holo-systolic RIGHT sternal murmur (due to VSD) OR a systolic ejection murmur at LEFT base (due to pulmonic stenosis)
CS: chronic hypoxia leads to increased erythropoietin and utlimately polycythemia!! syncope, cyanosis, exertional weakness
how do you diagnose tetralogy of fallot`
rads: underperfused lungs - reduced pulmonary vasculature (hardly see any vessels)
how do you treat tetralogy of fallot?
periodic phlebotomy
medical management of CHF (furosemide, enalapril, amlodipine, pimobendan, beta blockers, diltiazem)
hydroxyurea (goes to bone marrow and decreases production of RBCs)
what is the surgical option of treatment for tetralogoy of fallot?
what is the ultimate px of tetralogy of fallot?
subclavian artery transposition to create a PDA - gets more oxygenated blood thru the system
middle aged if mild
what ECG abnormalities will you see with a hyperK?
- no P waves!
- TAAAALL T waves!
- QRS complex wide and bizarre
- low HR
which breed is predisposed to sick sinus syndrome (screwed up SA node)?
schnauzers
what is the rate at which the SA, AV and myocardial muscle cells operating at?
SA node is fastest: 80 - 120 bpm
next is AV node: 60 - 80 bpm
ventricular myocardial cells: 40 - 60bpm
boxer is predisposed to what cardiomyopahty
arrhythmogenic Right Ventricular complexes (ARVC)
effect of beta 2 adrenergic receptors on the heart?
work on sympathetic system - relaxes it
slooooow down the HR
dilate vessels
in contrast to Beta-1 receptors which speed things up
effect of alpha 2 adrenergic receptors on the heart?
increase diastole
- INCREASE HR
- increase contractility
atrial premature contractions (APCs)
a P wave that comes early
its due to another part of hte atria depolarizing instead of the SA node
will be a fast, irregular rhythm
tx: sloooow down HR: positive ionotrope - digoxin
atrial fibrillation
ecoptic pacemaker: signal is coming from different pacemakers
- irregularly irregular rhythm
- more P waves than QRS complexes
- treat when BP drops below 80 bpm: want to SLOW HR: beta blockers (esmolol), Ca channel blockers (diltiazem), digoxin
- causes: anything that causes LA enlargement - DCM, mitral endocardiosis, HCM
what do positive ionotropes do?
- decrease atrial arrhythmias but increase ventricular arrhythmias
- slows conduction thru AV node to slow HR
ventricular premature complexes (VPCs)
- wide and bizarre QRS
- when they look different its bc they are coming from different places
- treat in hospital with lidocaine (Na channel blocker)
ventricular tachycardia
arrhythmia coming from ventricle (so SA and AV node are both not working). defined as >3 consecutive VPCs
- premature complex: decreasing R-R interval
- REGULAR rhythm
- watch for R-on-T!! risk of ventricular fibrillation!
- tx: treat ventricular arrhythmia by giving lidocaine up to 3 times then try procainamide. or you can try just slowing down HR a bit by giving esmolol or diltiazam.
- if dog is unconscious defibrillate (defibrillation works in a-fib and v-tach)
what are class1a drugs?
drug type
what they treat
examples of drugs
fast Na channel blockers
treat: V-tach, supraventricular tachycardias
ex: procainamide
what are class 1B drugs?
drug type
what they treat
examples
Na channel blockers
treat: VPCs, supraventricular tachycardias, v-tach
ex: lidocaine
what are class 2 drugs?
drug type
what they treat
examples
beta blockers - increase conduction time
treat: supraventricular tachycardias and v-tach
ex: atenolol, esmolol, propranolol
what are class 3 drugs?
drug type
what they treat
ex
prolong action potential and refractory period
treat: used to prevent v-tach and sudden death
ex: sotalol (dirty beta blocker), amodarone
class 4 drugs
drug type
what they treat
ex
Ca channel blockers, slow (L-type) channel inhibitors,
treat: supraventricular tachycardia
ex: diltiazem
what drug options are there fore tachycardia?
digoxin - increases contractility, decreases speed of normal conduction
diltiazem - central acting Ca channel blocker, slows conduction thru AV node
what drugs ares used in emergency situations for sinus tachycardia?
fast Na channel blocker: procainamide
Beta blocker: amiodarone
in what 3 instances do you treat V-tach
- when you have a run of complexes ( > 3)
- when they are different shapes (coming from different locations)
- when you have R-on-T phenomenon
what are some mechanical (non-medical) things you can do to treat V-tach?
vagal maneuver - push on both eyeballs, stimulates vagal tone and slows or blocks re-entrant supraventricular tachycardia temporarily
precoridal thumps - punch the area where you feel precordial thrill, can disrupt the reentrant circuit
ARVC (arrhythmogenic Right Ventricular Cardiomyopathy)
- aka boxer cardiomyopathy
- causes fibrotic myocarditis
- will see large number of VPCs
- risk of going into ventricular tachycardia
- dx: holter monitor
- tx: beta blockers to decrease HR (sotalol)
slow irregular bradyarrhythmias are a result of what?
increased vagal tone due to GI disease, resp disease or vagosympathetic trunk masses
how do you diagnose and treat a sinus bradycardia?
atropine challenge
if responsive, the HR will increase by 150%
tx with a placemaker
sinus arrest or atrial standstill
sinus node stops firing so the AV node takes over
- no P for every QRS
sick sinus syndrome
aka “tachycardia-bradycardia syndrome”: its a condition where the SA node is not working properly
- will see episodic weakness or syncope
- tx with pacemaker + beta blocker
who is the poster child of sick sinus syndrome?
female schnauzers
1st degree AV block
long P-R interval with no dropped beats
no real tx necessary
2nd degree AV block: Mobitz type 1
aka Wenckenback
- P-R interval increases until you get a P without a QRS
2nd degree AV block: Mobitz type 2
- P-R interval remains the same
- tx with a pacemaker
3rd degree AV block
no relationship between Ps and QRS complexes
- the P-R intervals will constantly vary with no pattern
- often has ventricular escape beats or AV nodal beats
- tx w/ pacemaker
what breed of cat is predisposed to HCM?
maine coons
rag dolls
persians
HCM pathophys
progressive disease - a type of idiopathic Left Ventricular hypertrophy
- progressively higher LV filling pressure
- leads to high LA and pulmonary vein pressure
- leads to progressive LA dilation
- which causes pulmonary congestion and edema
what are clincal signs of HCM?
- thrombus formation (think saddle thrombus)
- outflow obstruction
- atrial fibrillation
- L-sided heart failure
- thickened walls
how do you treat HCM?
want to slow the heart down!
- beta blockers: atenolol
- Ca channel blockers: diltiazem (central), amlodipine (peripheral vasodilator)
- Ace inhibitor: benazepril/enalapril (decreases afterload)
- super low doses of aspirin to decrease platelet function to lessen the formation of thrombus
restrictive cardiomyopathy
left ventricular endomyocardial fibrosis
systolic murmur
gallop rhythm
dx: echocardiograph; shiny lines in heart
peritoneo-pericardial diaphragmatic hernia
congenital disease
cats: DLH, persians, himalayans
dogs: weimeraners
- presents like heart disease
- dx: rads
- tx: only needed if animal shows clinical signs via sx
