Cardiology Anatomy, Function, & Disease Flashcards
What is the function of the cardiovascular system?
1) To pump blood, delivering oxygen, nutrients, and water while removing carbon dioxide and metabolic waste
2) To provide thermoregulation (vasoconstrict and dilation)
3) To support body functions (urine formation in kidney, gas exchange in lings, digestive processes and absorption, reproductive system functions
fibrous sac that surrounds the heart
contains a trivial amount of fluid for lubrication
pericardium
Track the flow of blood:
Right Ventricle > ________> Lungs > _________>Left ventricle >____>Tissues >_______
Pulmonary artery
Pulmonary vein
Aorta
Cranial/Caudal vena cava
Do the atrium or ventricles have higher pressure
ventricles
the auricular appendages have
numerous muscle bundles- pectinate muscles
What is significant about the auricular appendage in a cat with heart disease
If a cat has advanced heart disease there might be static blood flow and a dilated left auricular appendage
this makes it so that blood sits there and can lead to an arterial thromboembolism
What three vessels enter into the right atrium
1) Cranial Vena Cava
2) Caudal Vena Cava
3) Coronary sinus (venous return from the myocardium)
Provides venous return from the myocardium to the right atrium
coronary sinus
where do the pulmonary veins go
they go into the left atrium where blood will then go into the mitral valve into the left ventricle
how many papillary muscles does the left ventricle have?
What about the right ventricle
LV: 2 papillary muscles connecting chordae tendineae to the mitral valve
RV: 3-5 papillary muscles connecting chordae tendineae to the tricuspid valve
Pressures on the right side of the heart are generally ______ to _____ the pressures of the left size
1/5 to 1/6 the pressures of the left sides
LV=130mmHg
RV: 25mmHg
LA=0-10mmHg
RA=0-5mmHg
Aorta 130/105/90 mmHg
Pulmonary artery 25/18/12mmHg
the valve that separates the RA from RV
tricuspid
the valve that separates the RV from PA
pulmonary
the valve that separates the LA from LV
mitral valve
the valve that separates the LV from Ao
Aortic valve
How many leaflets does the mitral valve have?
2
Anterior leaflet: short circumference, long length
Posterior leaflet: large circumference, short length
How many leaflets does the tricuspid valve have
2 to 3 leaflets, larger circumference
Atrioventricular valves (Mitral and Tricuspid) must be _______ during diastole and __________ during systole
open in diastole (when ventricle is relaxing, allowing filling of ventricles)
closed in systole (when ventricles contract, valves closed, preventing backflow)
What is the most important heart disease of the dog
Myxomatous mitral valve degeneration
-degeneration of the mitral valve -> causes backflow from LV to the LA
How many leaflets do they semilunar valves have?
Three
What do the left and right aortic valve cusps have
coronary ostia
when diseases, semilunar valves may either be stenotic (not open fully) or be regurgitant (leaky)
Semilunar valves are ______ during systole and _____ during diastole
open in systole
closed in diastole
What is the most common congenital heart defect in dogs
Pulmonary Valve Stenosis
stenosis of the pulmonary valve where the leaflets are fused and fail to open properly
cant get blood out of the right ventricle -> creates more problems for right ventricle, working harder
where do the left and right coronary arteries arise from
from the aorta
flow occurs during diastole
when does left and right coronary artery blood flow occur
during diastole
arises from the right ventricle and delivers deoxygenated blood to the left and right lungs
pulmonary artery
brings oxygenated blood back from the lungs to the left atrium
pulmonary veins
inlet throught the mitral valve and outlet through the aortic valve
V shaped chamber: mitral and aortic valves are in fibrous continuity
left heart
inlet through the tricuspid valve
outlet through the pulmonary valve
geographically separate valve U-shaped chamber
right heart
the right heart is ____ shaped while the left heart is ____ shaped
R: U
L: V
where do cardiac impulse start
Sinoatrial (SA) node
propagate cell to cell
and are rapidly disbursed through the specialized conduction pathways
what are the two primary difference between fetal and adult circulation
-Flow across the atrial septum
-Flow between the aorta and pulmonary artery
In the fetal circulation: deoxygenated blood goes from the pulmonary artery to the ________ and then to the _______ where it becomes oxygenated. This then returns through the _________and travels across the __________ to the left heart and body
pulmonary artery to the aorta (via ductus arteriosus) and then to the placenta to be oxygenated. Returns through the umbilical vein and then across the atrial septum (foramen ovale) to the left heart and body
The heart develops initially as a _______
linear tube
has a venous pole (inflow) and arterial pole (outflow)
the heart tube undergoes looping as it bends to the right and primitive chambers begin to take shape
Septation then occurs as the atrial chambers, ventricular chambers, and great vessels twist and divide to result in final cardio anatomy
What are the different diagnostics that you can do for the heart
1) auscultate
2) Electrocardiography
3) Radiography
4) Echocardiography
5) Ambulatory monitoring
6) Cardiac catherization
What are the general therapies for heart disease (Broad)
medical treatment
surgery
transcatheter intervention
Phases the cardiac cycle
1) Atrial contraction
2) Isolvolumic contraction
3) Rapid ejection
4) Reduced ejection
5) Isovolumic relaxation
6) Rapid (early) filling
7) Reduced filling (diastasis)
Systole: 2-4
Diastole: 5-7
Systolic pressures are markedly different between the right and left ventricles but what is the same between them?
Volumes
closure of what valves defines the onset of systole
Atrioventricular valves
-Mitral (Left Atrioventricular)
-Tricuspid (Right Atrioventricular)
*closure prevents flow from atria into ventricle
*First heart sound
closure of what valve defines the onset of diastole
Aortic/Pulmonic valve
What makes the noise of the first heart sound (S1)
Closure of the Atrioventricular valves
-Mitral (Left Atrioventricular)
-Tricuspid (Right Atrioventricular)
creating the abrupt stop in blood flow
What makes the noise of the second heart sound (S2)
Closure of the aortic and pulmonic valves creating abrupt change in blood flow
the volume of blood ejected from ventricle in one cycle/contraction
Stroke Volume
End-Diastolic Volume (EDV) - End Systolic Volume (ESV)
aka
What you start with (End Diastolic is after filling) minus the end-systolic volume (after ejection of the ventricle)
the percent of blood that leaves the ventricle in each cycle
the ejection fraction
= SV (EDV-ESV) / EDV
What is the equation for stroke volume
End-Diastolic Volume (EDV) - End Systolic Volume (ESV)
aka
What you start with (End Diastolic is after filling) minus the end-systolic volume (after ejection of the ventricle)
What is a normal ejection fraction
> 50-60% is normal
ex: if lower- you are not ejecting enough (ex- DCM)
cardiac output equation
Stroke volume x heart rate
Total volume of blood pymped into the Aorta and Pulmonary artery in 1 minute (L/min)
Cardiac output
T/F: cardiac output is equal for right and left ventricle
True
What is the gold standard method for measuring cardiac output
invasively via a catheter in the pulmonary artery
not really done
where is the catheter for cardiac output measurement placed
Pulmonary artery
-extremely invasive
cardiac index
a method used to normalize cardiac output in regards to body size (weight, body surface area)
Right sided systolic pressures are generally _____ the left
1/5 the left
if hole in ventricle, there will be flow from left to right
What occurs during filling (diastole)
the mitral valve opens and passive filling and due to compliant left ventricle you get filling.
What occurs during isovolumic contraction
after the mitral valve closes and ventricle is full of blood, the ventricle begins to contract to generate enough pressure to force the aortic valve open
The period in which the ventricle is at its max volume of blood
End-diastolic volume is fulfilled once the mitral valve closes. isovolumic contraction then occurs
what occurs during ejection
after isovolumic contraction, the aortic valve will be forced open. Volume plummets and there is a gradual rise in pressure
Ventricles start to relax
What occurs during isovolumic relaxation
after ejection (now at end-systolic volume), the aortic valve closes (S2 heart sound) the ventricle then relaxes
If ESV is 50 and EDV is 120. what is the stroke volume
70mL
If ESV is 50 and EDV is 120. what is the ejection fraction
70/120 = 58%
> 50% is normal
What is the area of the pressure-volume work
external work of the heart
diastolic wall stress or pressure just prior to contraction (related to sarcomere length)
volume effects this
Preload
systolic wall stress or pressure (load or force on contracting cardiomyocyte)
afterload
the degree the muscle fibers shorten independent of the laod
Contractility (inotropy)
the degree of ventricular compliance and diastolic function
relaxation (lusitrophy)
How does an increase in preload affect stroke volume
Increased preload
increases stroke volume (increased EDV)
How does an increase in afterload affect stroke volume
Increased afterload decreases the stroke volume (Increased ESV)
Why does heart rate only increase cardiac output up to a point
because less diastolic filling time leading to less stroke volume
CO starts to fall at HR >180-200bpm in dogs
CO begins to decrease once HR reaches (dogs)
above 180-200 because there is less diastolic filling time
T/F: Increases in HR increases contractility of the
true
treppe and Bowditch effect
What factors influence preload
*Venous Return is most important
more blood returning to ventricles
increased end-diastolic volume and therefore pressure (up to a point) increases stroke volume (independent of contractility)
Frank-Starling’s Law
-assumes afterload and contractility remain constant
Intrinsic property of cardiomyocytes where increase in sarcomere length increases optimizes overlap of actin and myosin AND TnC Ca2++ sensitivity -> increases rate of cross bridge complex formation and velocity of myofiber shortening
Frank-Starling’s law
How can you increase preload and therefore cardiac output
give a fluid bolus
What affects afterload
*Think impedance to ejection
1) Systemic vascular resistance (and thus arterial blood pressure)
2) Compliance of the aorta and arteries
3) Left Ventricular outflow tract anatomy (subaortic stenosis)
4)
How does subaortic stenosis affect afterload
it increases afterload
decreases stroke volume
increases ESV
What is LaPlace’s Law
Wall stress = (Pressure x Radius) / (2x wall thickness)
if there is an increase in systolic pressure (increased afterload) the
heart compensates will compensate and get thicker to overcome that increased pressure
ex: Subaortic stenosis leads to a marked increase in LV systolic pressure and the wall thickens to reduce wall stress (more fibers share that load)
Normal RV is _____ the thickness of the normal LV
1/3
How can you decrease afterload and therefore increase stroke volume
Give a vasodilator
drugs that increase the contractility (degree/velocity muscle fibers shorten) due to increase Ca2+ influx or sensitivity to Ca2++
Positive inotropes
What are clinical surrogates used to measure heart contractility (inotropy)
Gold standard: Slope of end-systolic pressure volume relation (ESPVR) line
ejection fraction, shortening fraction are influenced by load and are therefore called indices of systolic function
What is the gold standard of heart contractility (inotropy)
Slope of end-systolic pressure volume relation (ESPVR) line
-Increased contractility affects SV (increased), EDV (-), ESV (decreased)
Do changes in preload and afterload influence contractility
No they all affect cardiac output but preload and afterload do not influence contractility
How does impaired relaxation (lusitropy) affect stroke volume
Decreased stroke volume because there is decreased EDV from diastolic dysfunction aka there is less compliance and ability to take to fluid from the atria
When is the energy in blood delivered the muscle cells via the cornoary arteries
during diastole
What determines myocardial oxygen consumption/demand (MVO2)
1) Heart rate (increased creates more oxygen demand)
2) Wall stress/pressure- hypertrophied hearts require more energy
3) Contractility - increased inotropy consumes more oxygen
What drugs decrease the MVO2
Beta-blockers (blocking sympathetic)
Drugs that increase the parasympathetic
Is there more blood in the veins or arteries
Of the 84% of total blood volume in the systemic circulation
-64% in veins
-13% in arteries
-7% in arterioles and capillaries
*Veins are a major pressure volume
the major volume reservoir
easily expand and contract to meet demands
high compliance
systemic veins
the major pressure reservoir
preserve pressure to propel blood
low compliance
systemic arteries
do arteries or veins have high compliance
veins
Blood flow is going to increase if you have
a low vascular resistance
pressure = flow (Q) x resistance (R)
Ohm’s law of fluod
Change in Pressure = Flow (Q) x Resistance
Blood flow through a blood vessel is dependent on
1) Pressure difference gradient across the vessel
2) Vascular resistance (friction of blood as passes along endothelium )
measured as displacement of volume per unit time
blood flow
ex: cardiac output
How can you measure cardiac output non-invasively
via echo estimation (freeze image during systole and at diastole)
What does Poieuille’s law tell you
you can predict the flow (or resistance) based on the geometry of the tube
1) Flow is directly proportional to r^4 Blood vessel radius/diameter has a huge impact on flow and resistance
altering blood vessel diameter is a powerful tiil to alter blood flow
2) Flow inversely proportional to blood viscosity
How does blood viscosity affect blood flow
it is inversely proportional to blood flow
As you increase driving pressure of blood it will change from
laminar blood flow to the turbulent blood flow
radius, blood densityand viscosity are all factors that influence this
turbulent blood flow across a heart valve
murmur