Thoracic cavity/exudates
what are the 2 main types of pleural effusions?
transudate and exudate
transudate - increased hydrostatic and osmotic imbalances, hypoalbuminemia, clear fluid, low protein, low nucleated cell counts
exudate - increased vessel permeability (inflammation), cloudy/turbid fluid, protein rich, high nucleated cell count
what separates the right and left ventricles?
Interventricular septum
describe the conduction system of the heart. (what nodes does it start with and where those the electrical signal travel?)
sinoatrial node in the right atrium
atrioventricular node
bundle of his
bundle branches
purkinje fibers
what does the T wave represent in an ECG?
repolarization of the ventricles
A dog with sinus bradycardia requires emergency treatment to increase heart rate. The veterinarian administers a muscarinic receptor antagonist that works rapidly but only lasts 30–60 minutes.
Which drug was most likely used?
atropine
a muscarinic antagonist used in emergency settings for bradyarrhythmias because it:
what is the difference between parietal layer and the visceral layer?
visceral - covers/adheres to the organ
what is the interventricular groove located on the left side of the heart? and which one is on the right?
paraconal - left
subsinusoidal - right
What step comes after partial repolarization (Na+ channels close/slight efflux of K+) in an action potential of the contractile phenotype of cardiomyocytes?
Plateau phase - influx of Ca2+ and efflux of K+
which lead placement is standard for a right lateral ECG in dogs
white - right front
black - left front
red - left hind
(white on right, smoke over fire, clouds above the grass)
A horse is diagnosed with atrial fibrillation. The veterinarian selects an antiarrhythmic drug that prolongs the refractory period of atrial cardiomyocytes and belongs to Class Ia of the Vaughan-Williams classification.
Which drug is most appropriate?
Quinidine
is a Class Ia sodium channel blocker that:
It is commonly used in horses with atrial fibrillation.
what are the boundaries of the thoracic cavity?
cranial - thoracic inlet
caudal - diaphragm
dorsal - thoracic vertebrae and hypaxial muscles
ventral - sternum
where do heartworms accumulate in the heart?
what happens in phase 4 of autorhythmic cardiomyocytes
transient Ca2+ voltage channels open and finish prepotential
which lead measures the voltage difference between the right forelimb (negative) and the left forelimb (positive)?
Lead I
A dog presents with supraventricular tachycardia. The veterinarian administers a drug that blocks calcium channels in the AV node, slowing conduction and increasing the PR interval.
Which drug was administered?
Diltaizem
is a Class IV antiarrhythmic drug (calcium channel blocker) that acts primarily on the AV node.
what are the 3 types of capillary classifications and describe each one?
continuous - lacks fenestrations
fenestrated - endothelium contains pores
sinusoidal - endothelium contains large pores, basement membrane may be discontinuous
considering the arterial supply to the heart, which coronary artery is larger in dogs and ruminants? which one is larger in the horse?
Left coronary artery is larger in dogs and ruminants
right coronary artery is larger in the horse
what is the intracellular reservoir for calcium in cardiomyocytes?
sarcoplasmic reticulum
what wave of ECG in a healthy dog is expected to be an upward deflection with a higher amplitude in lead II?
R
A dog with ventricular tachycardia is treated with a drug that blocks sodium channels and slows phase 0 depolarization, reducing conduction through rapidly conducting tissues such as the His-Purkinje system.
Which drug is most likely responsible for these effects?
Lidocaine
is a Class Ib sodium channel blocker used primarily for ventricular tachyarrhythmias.
A 7-year-old domestic short-haired cat is presented to the clinic with labored breathing.Thoracocentesis is performed, and a clear, pale-yellow fluid is removed from the pleural space.The fluid analysis shows high protein content (>2.5 g/dL) and a low nucleated cell count. Further workup reveals the cat has hypertrophic cardiomyopathy. Is this fluid transudate or exudate and what is most likely causing this to occur?
Transudate; due to increased hydrostatic pressure from heart failure
how can you tell the difference between the left lateral view of the heart and the right lateral view of the canine heart?
left lateral = auricular view: you can clearly see the left auricle, conus arteriosis, paraconal interventricular groove, aorta, and pulmonary trunk.
right lateral = atrial view: can clearly see the right ventricle, subsinusoidal interventricular groove, azygous vein, caudal/cranial vena cavas
what are the differences in cardiac activity during sympathetic stimulation vs parasympathetic stimulation?
chronotropism - Heart rate - S: increased P: decreased
dromotropism - speed of conduction - S: increased P: decreased
bathmotropism - excitability - S: increased P: decreased
inotropism - force of contraction - S: increased P: limited effect on contractility to ventricles
which arrhythmia is characterized by irregularly irregular R-R intervals without P waves?
atrial fibrillation
A 7-year-old Doberman Pinscher is treated for a ventricular arrhythmia with an antiarrhythmic drug that blocks potassium channels and prolongs the action potential duration and refractory period. Several weeks later the dog develops anorexia, vomiting, neutropenia, and hepatotoxicity. what drug was most likely given?
Amiodarone
is a Class III antiarrhythmic drug (potassium channel blocker) that prolongs repolarization and the refractory period, making it useful for treating tachyarrhythmias.