Exam 2 Flashcards
Defintion of syncope
Sudden, transient loss or depression of consciousness and postural tone resulting from transient and diffuse cerebral malfunction with spontaneous recovery.
Often due to deprivation of energy substrates (glucose or oxygen)
Definition of pre-syncope
An incomplete form of syncope
Definition of seizure
Abnormal excessive paroxysmal synchronous discharge in a population of neurons
Dysfunction of grey matter, which may be primary in origin or secondary to a metabolic abnormality
Can be tonic clonic or psychomotor
Definition of narcolepsy and cataplexy
Narcolepsy - dog collapses into sleep
Cataplexy - sudden onset of muscle paralysis
Can be induced by excitement or eating
Dogs can usually be roused by stimulation
Inherited forms in poodles, labradors, dobermans
Characteristics of fit (seizure)
Pre-ictal phase Marked limb movement, urination, defecation Completely unresponsive Long duration (>3 min) Gradual recovery Behavior change Evidence of other neurological disease
Characteristics of fainting (syncope)
Sudden onset Provoking event (vomiting, sudden change in level of activity) Flaccid collapse Followed by opistotonus Completely unresponsive Short duration (< 1 min) No limb movement Generally rapid and complete recovery
Characteristics of “falling over”
Elderly dog with musculoskeletal disease
Usually multiple events at exercise prior to presentation
Gradual onset
Variable duration
Dog becomes recumbent but no loss of consciousness
No spontaneous limb movement, urination, or defecation
Quick, complete recovery
Evidence of pain on clinical exam
Physical exam findings associated with syncope
Pale or cyanotic MM Hypo or hyperkinetic pulses Distention of jugular pulses Neurological deficits Gallop rhythm Murmur
Cause of syncope in humans
46% non-cardiogenic
36% undiagnosed
16% arrhythmias
2.5% obstructive cardiac disease
(Probably similar in animals)
What kind of hematological disorders can cause syncope?
Anemia
Polycythemia
Myeloproliferative disease
Which endocrine disorders can result in syncope?
Cushings, Addisons DM, DKA Hyperinsulinemia/insulinoma Pheo HypoT4
Which muscular disorders should be differentials for a patient presenting for syncope?
Polymyositis Muscular dystrophy Myopathy secondary to hypoK+, steroids, myotonia Labrador and retriever myopathy Mitochondrial myopathy
Which neurological disorders should be differentials for a patient presenting for syncope?
Thrombi Hemorrhage Space-occupying lesions Atheroscleosis Seizure Vestibular or cerebellar disease Spinal trauma Narcolepsy/cataplexy
Which musculoskeletal disorders should be differentials for a patient presenting for syncope?
DJD Polyarthritis Panosteitis Hypertrophic osteodystrophy Bilateral ACL rupture
Which neuromuscular disorders should be differentials for a patient presenting for syncope?
Myasthenia
Botulism
Peropheral polyneuopathies
Which drugs can cause iatrogenic syncope?
Digoxin
Vasodilators (phenothiazine derivatives, ACE inhibtors, beta blockers, CCB)
Quinidine
Class 3 agents (cisapride, sotalol)
What effects will class 3 agents have on a patient’s ECG?
Prolonged QT interval
Which congenital heart diseases can cause syncope?
Obstruction to outflow (AS and PS, tumors, endocarditis)
Tetralogy of Fallot
Shunts (VSD, PDA)
Severe AV valve dysplasia
What physical exam finding may indicate that a patient has a R->L PDA?
Cranial MM pink
Caudal MM cyanotic
What acquired cardiac disease can cause syncope?
Severe AV valve disease Systolic dysfunction (e.g. DCM) Pericardial disease Pulmonary hypertension Arrhythmias
Which bradyarrhythmias can cause syncope?
Sinue bradycardia
Sick sinus syndrome
AV Block (2rd and 3rd degree)
Atrial standstill
Which tachyarrhytmias can cause syncope?
Afib
Atrial flutter
Supraventricular tachycardia
Ventricular tachycardia
Treatment for VPCs?
Lidocaine
Treatment of ventricular tachycardias?
Lidocaine, K+
Esmolol, sotalol
Classes of anti-arrhythmic drugs
1: Na+ channel blockers
2: B blockers
3: K+ channel blockers
4: Ca+ channel blockers
If an animal is presenting with collapse and ECG shows multiple episodes of profound bradycardia, what is a likely diagnosis?
Vasovagal (neurally-mediated) syncope
What is the treatment for vasovagal (neurally-mediated syncope)?
None if infrequent
If situational, avoid situation
Sympathomimetics
Beta blockers, mineralocorticoid supplementation
Pacemaker
Two types of leads in pacemakers
Passive fixation
Active fixation
What ECG characteristics are representative of atrial fibrillation?
No P waves
Supraventricular
Irregular
Fast
What are the goals of treatment for atrial fibrillation?
Slow HR
Convert to NSR
Provide inotropic support
Control CHF
Treatment for atrial fibrillation?
Ca channel blocker (diltiazem) beta blockers (EXCEPT IF CHF PRESENT)
Treatment for pericardial effusion
Furosemide (high dose IV)
Pimobendan
Drainage
Fluids (high dose IV)
How is blood pressure regulated?
Locally - NO and other metabolites mediate vasomotor tone
Systemically - Baroreceptor reflexes/sympathetic nervous system, RAAS, renal blood volume control
What are the three causes of systemic hypertension?
- White Coat Syndrome
- Primary hypertension
- Secondary hypertension
What is White Coat Syndrome?
Increase in BP due to measurement process or situation
Usually sympathetic stimulation with stress/excitement
Resolves when cause is eliminated
No treatment necessary
What is primary hypertension?
“Essential” or “idiopathic”
May be associated with subclinical renal disease
Uncommon in dogs and cats
What can cause secondary hypertension?
Renal disease
Adrenocortical disease (hyperadrenocorticism or hyperaldosteronism)
Diabetes mellitus
HyperT4
Pheo
Polycythemia
Acromegaly
Diet
Breed (sight hounds)
Iatrogenic
What is the most common underlying cause of secondary hypertension?
renal disease
What percent of cats with renal disease have hypertension?
20-30%
What is the correlation between degree of azotemia and BP?
No correlation
How does diabetes mellitus cause hypertension?
Blood volume expansion with hyperglycemia
Overproduction of renin
What percent of hyperthyroid cats have hypertension?
10-30%
How does hyperthyroidism cause hypertension?
Increased cardiac output
How does pheochromocytoma cause hypertension?
Increased cardiac output
Peripheral vasoconstriction
*May be episodic
How does polycythemia cause hypertension?
Increased blood viscosity increases peripheral vascular resistance
How does diet cause hypertension?
Salt intake
Little effect on BP in dogs and cats unless massive or pre-existing secondary hypertension
What drugs can cause hypertension?
Corticosteroids Phenylpropanolamine Cyclosporin A Erythropoeiten NSAIDs Electrolyte solutions Adrenergic agonists
Main tissues affected by hypertension?
Heart
Kidneys
Eyes
Brain
Effects of hypertension on the CV system
Concentric hypertrophy of LV (-> murmurs or gallops, CHF)
Arteriosclerosis
Hemorrhage
What is a prognostic indicator of effects of hypertension on kidneys?
Degree of proteinuria
What effects does hypertension have on the eye?
Tortuous retinal vessels
Papilledema
Retinal edema, hemorrhage, detachment, degeneration
Secondary glaucoma
Effects of hypertension on CNS
Hypertensive encephalopathy
Stroke
Behavior alterations, depression, ataxia, seizures, stupor coma, death
Can hypertension be diagnosed based off of one BP measurement?
Rarely
In cases where there are definite clinical signs or evidence of end-organ damage
How can you measure BP?
Direct - arterial catheter
Indirect - doppler and oscillometric methods
Advantages and disadvantages of direct BP measurements
Advantages: accurate, objective, repeatable, ability to measure systolic/diastolic/mean BP
Disadvantages: invasive, requires technical skills to place and maintain arterial access
Advantages and disadvantages of indirect BP measurement
Advantages: technically simple and non-invasive
Disadvantages:less repeatable and inaccurate with movement or inconsistent technique
What is the most accurate and repeatable non-invasive technique to measure BP in cats?
Doppler sphygmomanometry
Normal BP
> 150/95
>160/100 considered abnormal
At what blood pressure should treatment be initiated?
Moderate risk
160-179/100-119
At what blood pressure is there severe risk of end-organ damage?
> 180/120
Treatment of BP is based on
Clinical signs
Risk of end-organ damage
Treatment of hypertension?
Avoid high salt intake ACE inhibitors Ca channel blockers Adrenergic blockers Hydralazine Nitroprusside Diuretics
How do ACE inhibitors treat hypertension?
Block conversion of angiotensin I to angiotensin II
Vasodilation
Reduced secretion of aldosterone and ADH -> inc Na and H20 excretion
Dec sympathetic tone
Reduced cardiac and vascular hypertrophy
Reduces GFR and proteinuria
Adverse effects of ACE inhibitors in treatment of hypertension?
Decreased GFR and azotemia
Hyperkalemia
How do calcium channel blockers (amlodipine, diltiazem) work to treat hypertension?
Decreased calcium influx into vascular smooth muscle -> vasodilation
How to adrenergic blockers work to treat hypertension?
Decrease HR and contractility to dec CO
Treatment of choice for hypertension caused by hyperthyroidism?
Beta blockers
Treatment of choice for hypertension caused by pheochromocytomas?
alpha blockers
phenoxybenzamine, prazosin
How does hydralazine work to treat hypertension?
we don’t know
causes vasodilation
After initiating therapy for hypertension, how long should you wait to recheck BP?
7-10 days
When hypertension is controlled, how often should you monitor BP?
1-4 months
Normal pulmonary arterial pressure
25/10 mmHg
15 mmHg mean
How does hypoxia affect pulmonary vasculature
Causes vasoconstriction
Opposite of systemic circulation
What agents cause vasodilation in pulmonary vasculature?
NO
PGI2
O2
What agents cause vasoconstriction in pulmonary vasculature?
Thromboxane
Endothelin 1
Angiotensin II
Serotonin
Causes of pulmonary hypertension
Idiopathic
Increased PVR: Primary PHT HW disease Chronic pulmonary disease PTE High altitude Hypoventilation
Increased PBF:
Congenital cardiac shunts
Increased CO
Increased PCWP:
PA stenosis
L-sided CHF
What is the most common cause of pulmonary hypertension in FL? Overall?
FL: HW disease
Overall: L-sided CHF
Consequences of pulmonary hypertension
Reduced CO
Hypoxemia
Cor pulmonale
Clinical signs/physical exam findings associated with pulmonary hypertension
Clinical signs similar to other cardiopulmonary diseases
R-sided CHF Ascites Syncope Cyanosis Murmur
How can you diagnose pulmonary hypertension?
Measurement of pulmonary artery pressure
Direct = cardiac catheterization gold standard
Indirect = echo
What ECG findings are associated with pulmonary hypertension?
Deep S wave and right axis deviation (RV enlargement)
Tall P waves (RA enlargement)
Arrhythmias
Treatment for pulmonary hypertension
Treat underlying cause (EXCEPT R->L shunts)
Oxygen Diuretics ACEi NO Ca channel blockers Synthetic prostacyclins (cost prohibitive)
ET-1 receptor antagonists (cost prohibitive)
Phosphodiesterase inhibitors (sildenafil - most common tx)
Antithrombotics
Regulators of endothelial vascular tone
Vasodilators: NO and PGI2
Vasoconstrictor: ET-1
What is the pathophysiology of vascular remodeling in PHT?
Chronically elevated ET-1 ang Ag-II cause smooth muscle hypertrophy of vascular walls
Eventually is irreversible
What might thoracic radiographs show for a patient with PHT?
Pleural fluid/pulomary edema Cardiomegaly Tortuous, blunted pulmonary arteries Bronchial or alveolar pattern Bronchiectasis
PAP estimate equation
PG = 4 x V^2
Normal = 10-25
Prognosis for PHT
Poor-grave
What are the most common types of thyroid tumor?
Follicular cell adenoma
Adenomatous hyperplasia
What percent of thyroid tumors are malignant?
1-3%
Most of these are carcinomas
Clinical signs of hyperthyroidism
Weightloss Polyphagia Hyperactivity PU/PD Vomiting Diarrhea Anorexia
Common physical exam findings of hyperthyroid patients
Palpable thyroid nodule
Tachycardia
Murmur
Muscle wasting
What is the T3 suppression test?
Used to dx hyperthyroidism
Blood drawn for T3 and T4
T3 (cytomel) administered x 3 days
Draw sample 2-4 hr post last pill for T3 and T4
Normal cat will have suppressed T4
Hyperthyroid cat ill not suppress
Why measure T3? -> Assess client compliance
Treatment for hyperthyroidism?
Methimazole
Diet (Hill’s y/d)
I 131
Surgery
Not really recommended:
Propylthiouracil
Iopanoic acid
Most common type of hypothyroidism?
Acquired, primary (decreased T4)
Which breed is prone to secondary hypothyroidism due to pituitary malformation?
GSD
Breed predisposition for hypothyroididm?
Beagles, dobies, goldens
Clinical signs associated with hypothyroidism?
"Tragic expression" Corneal lipid deposits/lipemia retinalis Truncal alopecia Hyperpigmentation Hyperkeratosis Peripheral neuropathy Myxedema coma
Lab findings associated with hypothyroidism?
Hypercholesterolemia
Hypertriglyceridemia
Low T4
Treatment for hypothyrodism
Levothyroxine 0.02 mg/kg BID
Re-test in 6-8 weeks
Which breeds have an autosomal recessive gene for hypoadrenocorticism?
Standard poodle
Portuguese water dog
Nova Scotia duck tolling retriver
Physical exam findings with hypoadrenocorticism?
Hypothermia Pale MM, prolonged CRT Bradycardia Weak pulses Melena Depressed mentation