Clin Med - Cardiac 1

drraythe's version from 2016-03-15 12:58


Question Answer
Congestive heart failure (CHF) is what kinda dz?TRICK QUESTION: it is not a dz!!!! It is the END PRODUCT of just about every cardiac dz ever
Do NOT confuse an action potential w/ an ECG. Look at slide 3 for an action potentialResting → Depolarizing (rapid influx of Na) → Repolarizing phase (rapid efflux of K) → Undershoot → Resting state
Look at slide 4 for a CARDIAC action potential (NOT THE SAME AS AN ACTION POTENTIONAL)Start w/ resting phase 4
Rapid depol w/ Na is 0, 1 is the little hook where it goes up & then goes down slightly to flatten out
The flattened plateau is 2
The slightly more gradual decline is 3
Back to 4 where it's resting
What allows the cardiac action potential to have a plateau?Ca++!!!
Which cells are pacemakers in the heart?ALL CELLS have inherent pacemaker potential
How is it physiologically possible that a cell can work like a pacemaker?They have leaky Ca & K channels
Explain the difference btwn the absolute & relative refractory periodIn the absolute period, the Na channels are closed tight & no matter how big the signal, they will not open to create another action potential. In the relative refractory period, however, a stimulus which is BIG enough will overcome the closed Na+ gates to cz an action potential
How does the sympathetic nervous system affect the heart?It can ↑ things, of course. BUT, it can also turn things down - it all depends ON WHICH RECEPTOR the sympathetic system acts on (so symp will turn things on w/ B1, but turn them down w/ B2)
What factors is cardiac output composed of?CO = SVxHR (stroke volume times heart rate)
How does L heart CO compare to R heart CO?THEY ARE EQUAL! (L might be more distance but the lungs are a TON of space)
What factors is MAP (mean arterial pressure) composed of?CO x SVR (cardiac output times systemic vascular resistance)
Explain starling’s lawFluid movement = a constant ([capillary hydrostatic pressure-interstitial hydrostatic pressure] - [capillary oncotic pressure-interstitial oncotic pressure])
What is preload?The amount of blood coming back to the heart! Think of it as a volume - so an ↑ in preload to the heart is an ↑ in volume returning to the heart
What is afterload?The pressure the heart has to overcome to get blood out of the heart.
(Way to think of things) what are you trying to change by giving furosemide to a CHF PTx?Pee out fluid volume → ↓ preload!
(Way to think of things) analylpril (ace inhibitor) is given to CHF PTx to change what?Vasodilator → ↓ BP-↓ PRESSURE/work blood has to do to get blood out of heart → ↓ afterload
************What is the #1 priority of the heart?Maintain normal systemic arterial pressure!! It will kill itself trying to do this
**Explain the priorities of the heart, in the order of if cares the most to cares the least(1) MAINTAIN NORMAL SYSTEMIC ARTERIAL PRESSURE!!!!!!
(2) Maintain normal tissue blood flow
(3) Maintain normal systemic & pulmonary capillary pressures
(Example of how the heart always keeping normal systemic arterial pressure can be a bad thing) pathogenesis of mitral valve insufficiencyThe blood is going backwards through the mitral valve & not getting pushed out, which is ↑ the PRELOAD (volume) of the L heart. Also, that blood is not getting to the aorta, so there is a ↓ in CO. They kidney senses this & turns on compensatory mechanisms. The body starts to retain Na+Cl & water. This ↑ the BP. An ↑ in BP ↑ the preload of the right heart, which follows through that the preload of the L heart will be ↑ also...again. This ↑ the work the heart has to do more. & the blood is still flowing backwards!
What is the Frank-Starling Mechanism?The ability of the heart to change its force of contraction & therefore stroke volume, in response to changes in venous return (↑ volume-stretch receptors in heart stretched-tell heart to contract harder)
Frank-Starling Mechanism → check out pic on slide 10!Notice how there is the control loop & how an ↑ in venous return will lead to ↑ stroke volume. UNDERSTAND this chart!
↑ Venous return is basically what happening? What happens, how does the heart compensate & what is this called?Ie, the PRELOAD (end diastolic volume & pressure) ↑ but the end systolic volume is the same. This means the heart ↑ the FORCE OF CONTRACTION & therefore the STROKE VOLUME to compensate. This is the Frank-Starling Mechanism
Explain diagram on slide 10 (Frank-starling mechanism)(Remember this means if preload ↑, contractility ↑ to up the stroke volume to compensate)
As the left vent fills, the volume ↑ & the pressure ↑ a little. Then the valve closes & there is an ↑ in pressure (contraction) but no ↑ in volume. Then the pressure in the LV overcomes the pressure in the aorta & the aortic valve opens. Then there is a ↓ in volume in the LV, until the aortic pressure is ↑er than in the LV & the aortic valve closes-this czs a ↓ in the pressure in the LV w/ no volume change. This is the blue cycle. In the green, there is more volume entering the LV (preload) but in a healthy heart, the heart is just able to contract harder to overcome the aortic valve & still get the blood out
Check out graph on slide 11 about frank-starling mechanismsee how that in heart failure, the heart can only be contractile enough for being at rest-which is why THE 1st SIGN OF PROBLEMS is often exercise intolerance. Then, in cardiogenic shock, the heart isnt even able to contract enough to meet demands at rest.
WHAT IS USUALLY THE 1st SIGN OF CARDIAC DZ TO OWNERS? Why is this?Usually exercise intolerance. The Frank-starling mechanism explains this (see slide 11) bc a failing heart cannot compensate by contrActing more for an ↑ volume (if the animal can't even handle resting, it is in cardiogenic shock)
4 types of heart dzs/failuresVolume overload
Pressure overload
Pump failure
Electrical abnormalities
CS of heart dz that owners notice...Syncope (fainting-NOTE: owners might think this is a seizure)
Exercise intolerance
Abdominal distension
CS of heart dz that VETS notice...Pulse abnormalities
Jugular pulses
Bad heart are _________BIG
Bad hearts usually like to fail in which direction?Backwards! So L heart backs into lungs & R heart backs into abdomen/liver
(If you are asking your owner a Hx about a suspected heart dz, why might you ask about if theyve been to Texas?)Parasite: Trypanosoma (kissing bugs-aka reduviid bugs). End stage trypansoma will look like dilated cardiomyopathy
Signs of Congestive Heart Failure (CHF) are usually...Backwards failure!! So respiratory signs, ascites
Signs of↓cardiac output are usually... (What’s the onset like?)Usually late onset. This is a FORWARD failure (usually see backwards fail before forward so this is unique) & you will see Exercise intolerance, syncope, pre-renal azotemia, cyanosis
What are 5 major CS you see in CHF?(1) Pulmonary Edema (Canine/Feline Left sided backwards heart failure)
(2) Pleural effusion in cats (L OR R sided heart failure)
(3) Hepatic congestion/Ascites (Right Sided backwards heart failure)
(4) Jugular vein distension
(5) Cachexia (only 2 times you lose weight super-fast like this is in cancer or cardiac probs)
Whats the difference btwn pulmonary edema & pulmonary effusions & who usually gets what?EDEMA = water in lungs (cats or dogs). EFFUSION = water in chest outside of lungs, CATS ONLY.
Pulmonary edema in CHF usually occurs from what dz/prob? (Who?)Left sided backwards heart failure (dogs & cats)
Plural effusion in CHF usually occurs form what dz/prob? (Who?)Either left or right sided heart failure, IN CATS ONLY
Hepatic congestion/Ascites in CHF usually occurs from what dz/problem?Right Sided backwards heart failure
Arrhythmias can be due to what kinda things?(1) Structural or pathophysiologic remodeling (like Conduction abnormalities, Automaticity errors)
(2) Genetic factors
(3) Environmental stresses
(4) Ischemia
(5) Can be modulated by neuroendocrine factors (like epi & norepi)
How does a dog w/ heart problems appear?Anxious
Open mouth breathing
Orthopnea & elbows abducted
Tachypnea - short & shallow
Hyperpnea - ↑ depth
Explain Tachypnea vs Hyperpnea & when you see theseTACHY = Short & shallow, usually associated w/ pulmonary edema
HYPER = ↑ DEPTH, usually associated w/ hypoxia, hypercarbia
If a dog comes in presenting w/ syncope, what should you prolly do 1st?Figure out if it's actually syncope & not a seizure & vice versa
What CS ARE usually seen w/ syncope?Fainting
Exertion or excitement
Rear limb weakness
Sudden collapse
Lateral recumbency
Stiffening of the forelimbs & opisthotonos
What CS are NOT usually seen w/ syncope?Tonic/clonic motion
Facial fits
Aura (signs dog might have a sz before it happens), Post-ictal dementia (ictus is a seizure)
Neurologic deficits
GOLD STANDARD for working up a heart?MR (I)
Pulmonary edema would look like what on a rad?Air bronchogram
A dog comes in & is a walking, talking, breathing pure example of a heart problem. 1st test?RADS BEFORE ECHO. ALWAYS.
4 reasons for why an animal might be coughing?(1) CHF
(2) Mainstem bronchi compression
(3) Pneumonitis & vascular dz 2°to HWD
(4) Non cardiac dzs (airway dz, Parenchymal dz, pleural space dz)
What's a "cowboy sign" & when do you see it?(VD view) The left atrium is pushing the bronchi up & apart, the bronchi look like they are straddling the L atrium. Means enlarged L atrium
Why would you always palpate the chest, esp the precordium?(Precordium = portion of the body over the heart & lower chest) This is where you might feel a palpable thrill
Why on earth would you want to palpate the thyroid?CATS!! Hyperthyroidism can cz cardiac issues
If you are examining for Arterial pulse abnormalities, what should you be checking?Check Pulse pressure differences in conjunction w/ auscultation
Why would you want to do an eye exam if you suspected heart problems?BP problems might lead to hemorrhage & detachment of retina
What is the equation for pulse pressure? Why is it good to know this?Systolic pressure vs diastolic pressure (my notes say: palpate pulses on dog... there are bounding pulses. pulse pressure is diff btwn systolic & diastolic. so if something that drops diastolic & ↑ systolic → get bounding)
What is the jugular pulsing (general/not specific czs)?↑ VENOUS PRESSURE (however, the jug isnt pulsing, its just full & bouncing off of the carotid underneath)
Why might you see a jugular pulse?It is due to ↑ venous pressures, which can be from
(1) Right sided failure (Tricuspid dz, Pulmonary hypertension, Caval syndrome)
(2) Pericardial dz
(3) Volume overload
(4) Cranial mediastinal mass
Whats Caval syndrome & what might you see as symptoms of it?Worms stop living in pulmonary artery & start living in the heart (bc so many worms). See jugular pulses from ↑ venous pressure
Why do you see R heart signs (like jugular pulses) in Pericardial dz?Why signs of R heart failure-bc R heart smaller & wimpier (so opens up/collapses 1st)
What kinda mass can cz jugular pulse?Cranial mediastinal mass (in the way so incoming blood to the heart starts backing up)
Where do you ascult what valves etc for auscultation?PAM-T. 3-4-5-3/4
Which side of the body do you hear a PDA on? Why?LEFT side, bc the pulmonic valve is auscultated on the left & in PDA the aorta has blood backflowing into pulmonic arteries which pushes against the pulmonic valve
Which side of the body do you hear a VSD on? Why?RIGHT side, bc the L ventricle has ↑er pressure than the right, so the blood is pushed into the R ventricle & hits the R wall, so that's where you hear the turbulence
Check out the wigger diagram on slide 26Understand the timing of things-the S1/QRS comes just before the actual ↑ in LV pressure (contraction)
What's a holosystolic murmur aka? What does it mean?Aka plateau. Lasts for entirely of systole & doesnt get quieter (regurgiant or plateau)
(Corrigan pro tip) how can you help yourself get better & spot murmurs?Mutter lub-dub to yourself repeatedly in rhythm before you even put a steth on the animal
What a crescendo-decrescendo murmur & what does it mean?Gets louder & then quieter during systole. (Ejection)
4 types of murmurs?Holosystolic
Diastolic decrescendo
Continuous (machinery)
****How would you describe a grade 1 murmur?Very soft, intermittent (like only an expert can hear it)
****How would you describe a grade 2 murmur?Soft murmur, can hear consistently in a quiet room
****How would you describe a grade 3 murmur?Moderate intensity murmur (*if you hear a murmur when you just put the stethoscope on the dog, its a 3. IF you can hear it on the other side, it's a 4)
****How would you describe a grade 4 murmur?Loud murmur (if you can hear it on L & R sides)
****How would you describe a grade 5 murmur?Loud murmur w/ a precordial thrill (you can FEEL it!! little tickles on your fingers-not feeling the beat, but the turbulence)
****How would you describe a grade 6 murmur?Very loud murmur, can hear w/ stethoscope off of the body wall (if you can remove the steth & still hear it, it's a 6)
If you find out the dog has an anemia & you can hear a mild murmur, what are you thinking it MIGHT be?Anemia can cz physiological murmur bc the blood is thinner & it sloshes more
Endocardiosis vs endocarditis?Endocardiosis = Degenerative valve dz
Endocarditis = Valve infxn
If you detect a murmur, what is the 1st thing you wanna do diagnostically?CHEST RADS. ALWAYS FIRST
When is the only time you don't do chest rads 1st?Arrhythmia - do ECG 1st

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