Cardiovascular Flashcards
Cardiac action potential
-rapid change in membrane potential, or voltage, across the cardiac cell membrane
-triggers cardiac muscle contraction
Resting membrane potential
-when cardiac call of the ventricle is not electrically excited
-phase 4 (-90mV)
Main ion found outside the cell at rest
Sodium and Chloride
Main ion found inside the cell at rest
Potassium
Threshold potential
The critical level a membrane potential must reach to initiate an action potential
Depolarization
-phase 0
-voltage becomes more positive
-sodium influx
-potassium eflux
-rapid inactivation of sodium channels cause membrane potential to return to a negative state
Repolarization
-phase 1
Define preload
Volume present in the ventricle prior to systole (volume filling the heart)
Define afterload
Load (pressure) that the heart must pump against in order to eject blood
Define contractility
Intrinsic force of the heart - degree of which the sarcomeres can shorten
What are sympathetic nervous system effects on the heart
Increased contractility, increased HR
What are parasympathetic nervous system effects on the heart
Decreased chronotropy (HR) and contractility
Draw a ventricular action potential
Describe the flow of blood through the heart
cranial/caudal vena cava > right atrium > tricuspid valve > right ventricle > pulmonic valve > pulmonary artery > pulmonary vein > left atrium > mitral valve > left ventricle > aortic valve > aorta
Where can arterial catheters be placed
Dorsal pedal
Femoral
Auricular
Coccygeal
Lingual
What are the components of an arterial wave form
What are possible pulse abnormalities
Hypodynamic (decreased pulse pressure)
Hyperdynamic (increased pulse pressure due to decreased diastolic pressure)
Bounding (increased pulse pressure due to increased systolic pressure)
Pulses paradoxus - decrease in BP > 10 mmHg during inspiration
What are the types of cardiac hypertrophy?
Concentric - increased pressure overload (HCM)
Eccentric - increased volume overload (DCM)
What are the types of feline cardiomyopathy?
Hypertrophic cardiomyopathy
Dilated cardiomyopathy
Restrictive cardiomyopathy
Arrhythmogenic right ventricular cardiomyopathy
What breeds are associated with familial HCM
Maine Coon, Ragdoll
What are prognostic factors associated with feline ATE
Number of limbs affecetd
Temperature < 98.8
What is treatment for CHF in cats
Diuretic
ACE inhibitor
Antithrombotic
+/- Beta blocker
What is the most common site of clot FORMATION in cats with heart disease
Left auricle
What are secondary causes of DCM in dogs
Doxorubricin
Nutritional (taurine, carnitine)
Myocarditis
Grain free diet
Neoplastic
What is the MOST common canine heart disease
Mitral valve disease
What are the stages of mitral valve disease
A - at risk breeds
B1 - murmur with no cardiac changes
B2 - Murmur with left atrial enlargement
C - historic or current heart failure
D - refractory heart failure
What test can we run to evaluate myocardial contusions/myocarditis
Troponin
What are indications for a pacemaker?
High degree AV block
Sick sinus syndrome
Severe drug toxicity
What toxicities may result in requiring a pacemaker
Beta blocker
Calcium channel blocker
Digoxin
What is the role of POCUS
Thoracic, abdominal effusion
What are differentials for bradycardia?
Increased vagal tone
Electrolyte abnormalities
Drugs
Trauma
Infection
What does vtach look like?
Wide and bizarre QRS
No P waves
What are criteria to treat vtach
Hemodynamic instability
R on T
Multiform
Rate >180
What drug should be used to treat vtach
Lidocaine
What rhythms are defibrillation used for
Pulseless vtach
Vfib
Define defibrillation
Shock delivered to a critical mass of the myocardium resulting in depolarization and refractory period
What is the difference between monophasic and biphasic
Mono - undirectional flow
Biphasic - current moves in both directions
What are complications of pericardiocentesis
Arrhythmia, hemorrhage, myocardial puncture
What are physical exam findings consistent with pericardial effusion
Right sided CHF (ascites)
Jugular pulse
Muffled heart sound
Pulses paradoxus
Low cardiac output
What is pulses paradoxus
Great than 10 mmHg decrease in systolic blood pressure during inspiration
What are the common causes of pericardial effusion
Neoplasia
Idiopathic
Infectious
What is cardiac tamponade
Collapse of the right atrium during systole
What viral disease can cause myocarditis
Parvo
Define systole
Heart muscle contraction, pumps blood into arteries
Define diastole
Heart muscle relaxation, chambers refill with blood
