Basic Cardiac Principles Flashcards
List 2 functions of the circulatory system
- Maintains blood flow/ supply to body
- Deliver O2, nutrients & other needed substances to all of the body’s cells & removes the waste of metabolism
What is the number one cause of disease/ death in the US?
Cardiovascular disease
What is the primary role of the circulatory system?
Blood flow, getting oxygen
What do variations in HR and force of contraction need to match in order to meet changing demands of the body?
Need to match the amount of blood flow
When exercising do you need more or less O2?
More oxygen → thus increased blood flow
What happens to CV system when we are asleep?
Everything slows down
What happens to the heart in a person Dx with heart disease?
The heart enlarges, undergoes hypertrophy
Anatomy of the heart
4 chambers:
→ Right & left atrium
→ Right & left ventricles
What is the interface between blood & artery wall?
Endothelium
What cells line our blood vessels?
Endothelial cells
List the 5 metabolic functions of the endothelium
- Maintain vessel one
- hemostasis
- angiogenesis
- Neutrophil chemotaxis
- Hormone secretion
Define angiogenesis
Development of new blood vessels
Neutrophil chemotaxis plays a role in?
our immunity
What are 2 things the endothelium produces
Nitric oxide & endothelin
Why do endothelial cells & blood vessels love nitric oxide?
It keeps endothelial tissue nice & smooth (zamboni ex)
Injury to the endothelium causes ____
dysfunction
Epicardium
Very thin visceral layer of the heart (serous pericardium)
List functions of the epicardium
- Keeps the heart in place
- Helps protect heart from trauma or infection
What is another name for the epicardium?
Visceral pericardium
Pericardium
Parietal layer → Has fibrous pericardium & serous fluid
List one function of the pericardium
- Receptors elicit reflex changes in BP & HR
What could be considered the most important layer of the heart?
The myocardium (thickest layer)
Myocardium
Muscle layer of heart → need for proper pumping
Endocardium
Inner endothelial lining vessels of heart & made up of epithelial tissue (protects)
Name the 4 valves of the heart
AV valves:
1. Tricuspid
2. Mitral (bicuspid)
SL valves:
3. Aortic
4. Pulmonic
Heart valves play a role in?
Moving the blood along to where it needs to go
Where are the AV valves located?
Between the atrial & ventricular chambers on each side
AV valves prevent
Backflow into the atria when the ventricles contract
Bicuspid valve
The left AV valve → bicuspid/ mitral valve that consists of 2 flaps, or cusps of endocardium
Tricuspid valve
The right AV valve, the tricuspid valve, has 3 flaps
Semilunar valves
Guards the bases of the 2 large arteries leaving the ventricular chambers
List the 2 semilunar valves
- Pulmonary valve
- Aortic valve
Oxygen poor blood flow through the heart (deoxygenated)
SVC & IVC → right atrium → tricuspid valve → right ventricle → pulmonary valve → pulmonary arteries that carries blood to the lungs
Oxygen rich blood flow through the heart (oxygenated)
Pulmonary veins → left atrium → mitral valve → left ventricle → aortic valve → aorta to pump blood into systemic circulation
Each cardiac cycle consists of what 3 sequential events?
Diastole
Artial systole
Ventricular systole
About how long does each cardiac cycle last?
~ 0.8 seconds
What happens in diastole?
Both the atria & ventricles relax allowing blood to flow into the heart
filling phase
What phase makes us 2/3 of the cardiac cycle?
diastole
What happens in systole?
Heart contracts and pumps blood out of the heart
Phases of the cardiac cycle:
Atrial systole begins…
Atrial contraction forces blood into ventricles
Phases of the cardiac cycle:
First phase → ventricular systole
Ventricular contraction pushes AV valves closed
Phases of the cardiac cycle:
Second phase → ventricular systole
Semilunar valves open & blood is ejected
Phases of the cardiac cycle:
Early → Ventricular diastole
Semilunar valves close & blood flows into atria
Phases of the cardiac cycle:
Late → Ventricular diastole
Chambers relax & blood fills ventricles passively
Concepts r/t the cardiac cycle (5)
- Preload
- Contractility
- Afterload
- Stroke volume
- Cardiac output
Cardiac output
Amount of blood the heart pumps (ejects) per minute from the left ventricle
How is cardiac output measured?
Stroke volume X heart rate
Normal cardiac output range
4-8 L per minute
Stroke volume
Amount of blood pumped by the ventricles with each heartbeat
List the 3 factors that impact stroke volume impacting cardiac output
- preload
- afterload
- contractility
Preload AKA _____
Left ventricular end diastolic pressure (think stretching)
Preload is the stretching of ____
Muscle fibers in the ventricles to the greatest of their ability
Stretching during preload results/ depends on
the amount of blood in the ventricle at end of diastole
What happens at the end of diastole when the ventricle is filled & MV closes?
Preload
The more preload means…
The more blood you have in your heart in LV, which means the more blood getting out to the rest of the body (good thing)
Frank – Starling’s law says:
The more the heart muscles stretch during diastole the more forcefully it will contract at systole
Frank – Starling’s law:
The stretch increases to accommodate > volume which
- Increases sacromere length
- Increases the sensitivity of Ca++
- Strong contractions
List the 6 factors and 2 subfactors affecting preload
- ↑ aortic pressure
- ↑ atrial contractility
- ↑ ventricular compliance
- ↓ heart rate
- ↓ ventricular inotrophy
- ↑ central venous pressure
– ↑ thoracic venous blood volume
– ↓ venous compliance
What is thoracic venous blood volume?
Total blood volume located in veins of chest cavity
Determines venous return based on:
– respiration
–muscle contraction
–gravity
List 8 factors that increase preload:
- ↑ central venous pressure
- ↓ heart rate
- valvular regurgitation
- ↑ aortic pressure
- ventricular systolic HF
- ↑ circulating volume
- mitral insufficiency
- aortic insufficiency
List 7 factors that decrease preload:
- ↓ central venous pressure
- ↑ heart rate
- ↓ circulating volume (bleeding; third spacing)
- Mitral stenosis
- Vasodilator use (nitro)
- Atrial fibrillation
- Cardiac tamponade
What 4 things are affected when we have issues with our heart?
- Contraction
- Preload
- Afterload
- Circulation
What is contractility?
The ability of the myocardium to contract normally (squeezing of the ventricles)
An increased contractility causes what else to increase?
stroke volume
Contractility is influenced by _____
preload
Positive inotropy
Increased force of contraction
–decreased preload & afterlaod
Negative inotropy
Decreased force of contraction
- potentially ↑ preload & ↓ afterload
Example from class:
What happens to contractility if preload stretch is not strong?
Contractility will not be as strong
How do certain medications influence contractility?
Certain meds can have an increase or decrease on force of contractility
Afterload
Amount of resistance the heart must pump against when ejecting blood
Afterload:
What has to happen in order for blood to be ejected from LV?
The aortic valve must open to push it to the rest of the body
Afterload:
Kinked hose example from class in HF patient
HF patient has a heart that is not contracting great so it has to work so much harder to open up the valve & release the kink in the hose
When afterload is low…
the ventricle does not have to exert much effort to get the blood out of the heart
easy workload
What type of BP would you see if afterload is low
Normal → 110/60
When afterload is high…
It is increased due to increased systemic vascular resistance
vasoconstriction
What type of BP would you see if afterload is high?
Hypertension → 180/90
Why do people experience cardiomyopathy, enlarged heart or hypertrophy?
When heart starts to fail, there is more blood going into the heart than leaving it
Chronic pathologic changes to myocardium or heart tissue when it has to work extra hard?
Heart will get larger (hypertrophy)
How do you calculate ejection fraction?
Stroke volume/ preload
Normal EF range
55-70%
What is considered abnormal EF range
anything below 40%
Abnormal EF can be described as…
Not putting out a lot of oxygenated blood to the rest of the body
What nervous system stimulates a stress response?
Sympathetic nervous system
Sympathetic nervous system secretes _____ & _____ to increase blood flow to the _____, ______, ______, & _______ muscles
epinephrine & norepinephrine
heart, lungs, brain & skeletal muscles
What nervous system is considered the “fight or flight”
Sympathetic nervous system
When SNS is activated it decreases ______ & increases _______
preload; afterload
Beta receptors are primarily responsible for what?
signaling SNS
What should you think when you hear beta 1 receptors?
heart
What should you think when you hear beta 2 receptors?
More GI issues than cardiac
What is increased when beta 1 receptors are activated?
force of contraction
(increases actual rate of contraction)
Too much stimulation from beta 1 receptors can lead to
Abnormal arrhythmias
What happens when Beta 1 receptors are stimulated?
increases HR and contractility which increases SV and CO
What happens when beta 1 receptors are blocked?
HR & force of contraction will decrease
What do B1 receptors in the kidneys do?
Release renin & initiate RAAS & raises BP
B1 receptors in the heart increase?
Rate; force; automaticity; cardiac output
B1 receptors in adipose tissue are crucial for regulating:
Lipolysis (fat breakdown)
What beta receptor plays a role in glucose metabolism?
beta 2 receptors
What kind of system is RAAS
hormone signaling system that regulates blood volume, BP, plays a role in fluid & electrolytes, & systemic vascular resistance
What are the 3 main substances RAAS consists of?
Renin (enzyme), aldosterone (hormone), and angiotensin II (hormone)
How do these 3 main substances of RAAS help regulate BP?
increase Na reabsorption, water reabsorption, & vascular tone
What organ accounts for 20% of cardiac output?
Kidneys
When BP is low what do the kidneys release?
renin into the bloodstream
When renin is released it splits into?
angiotensinogen & goes to the liver
Angiotensinogen causes an increase in _______ __
angiotensin I
An increase in angiotensin I partly becomes an _____ form and goes where?
inactive form & goes to lungs where angiotensin converting enzyme (ACE) is released
What else does renin split into?
Angiotensin II
What occurs when angiotensin II is activated?
causes vasoconstriction which increases BP
Angiotensin II also triggers release of what 2 things that cause kidneys to retain Na
triggers adrenal gland to release aldosterone & pituitary gland to release ADH
What happens when the kidneys retain sodium?
leads to water retention which causes ↑ in BP and ↑ in blood volume
______ & ______ __ play a role in stimulating SNS
Aldosterone & angiotensin II
What is considered the “shredder of our blood vessels”
Angiotensin II
Inappropriate RAAS activation can be a cause of impaired _____ & _____ health
vascular & metabolic
What are the 5 characteristics of metabolic syndrome?
- hypertension
- obesity
- abnormal cholesterol levels
- chronic inflammation
- insulin resistance
What shaped people are at higher risk for cardiac problems?
Apple shape → carry weight in chest/ abdomen area (more visceral fat)
Define insulin resistance:
Insulin is not able to reduce blood sugar. compensatory fails as well & person remains hyperglycemic
What happens due to insulin resistance?
cells fail to make effective use of insulin
blood sugar increases
____ cells in the ____ secrete insulin
beta cells; pancreas
What happens in a normal person if blood sugar levels increase?
The glucose will reduce with insulin secretion & insulin levels decrease
We want glucose in ____ NOT _____
in cells NOT circulation
List 6 things insulin resistance causes:
- ↑ catecholamine
- stimulates Na reabsorption (↑ BP)
- endothelial dysfunction
- RAAS & SNS dysfunction
- ↑ smooth muscle proliferation
- BP often ↓ with meds that improve insulin sensitivity
Insulin:
An increase in smooth muscle proliferation leads to …
hypertrophy & TOD (target organ damage)
What category meds improve insulin senstivity?
ACE
Insulin is helpful for?
Vascular protection → ↑ endothelial cell production of nitric oxide
List 4 low-grade chronic inflammatory states
- CVD (↑ thrombosis)
- type 2 diabetes
- hypertension
- hyperlipidemia
What happens in endothelial injury?
- injury causes dysfunction
- starts inflammatory response
- release of nitric oxide is inhibited
- increased levels of vWF
Risk factors for CVD (9):
- HTN
- hyperlipidemia
- genetic susceptibility
- diabetes
- obesity
- physical inactivity
- smoking
- stress & tension
- aging
Risk factors for CVD lead to _____ _____ which leads to _____
Endothelial dysfunction; atherogenesis
All symptoms come from what two things?
- inadequate tissue perfusion
- disruption of supply & demand
Coronary symptoms
- stable angina
- unstable angina
Peripheral disease symptoms
Claudication
Cerebral symptoms
TIA & CVA
Difference between stable & unstable angina?
Stable → significant fixed lesion
Unstable → unstable plaque leads to MI (acute coronary syndrome (ACS))
What are the 4 types os percutaneous coronary intervention?
- Percutaneous transluminal coronary angioplasty (PTCA)
- Stent
- Atherectomy
- Thrombectomy
List 3 reperfusion strategies
- Pharmacologic agents (fibrinolytic therapy)
- percutaneous coronary intervention
- CABG
Question:
Which term is used to describe the amount of stretch on the myocardium at the end of diastole?
A. Afterload
B. Cardiac index
C. Cardiac output
D. Preload
D. Preload
Question:
What 2 factors are used to calculate cardiac output? (Select all that apply).
A. Heart rate
B. Blood pressure
C. Stroke volume
D. Mean arterial pressure
E. Systemic vascular resistance
A. Heart rate
C. Stroke volume
Question:
Which statement best describes cardiac afterload?
A. The volume amount that fills the ventricles at the end of diastole.
B. The volume of blood the ventricles must pump out of the heart.
C. The Amount of blood the left ventricle pumps with each heart beat.
D. The pressure the ventricles must work against to open the semilunar valves so blood can be pumped out of the heart.
D. The pressure the ventricles must work against to open the semilunar valves so blood can be pumped out of the heart.
Question:
A patient with hypovolemic shock is given IV fluids. IV fluids will help _________ cardiac output by __________________________:
A. Decrease; decreasing preload
B. Increase; increasing preload
C. Increase; decreasing afterload
D. Decrease; increasing contractility
B. Increase; increasing preload
Question:
Which of the following is the main difference between unstable and stable angina?
A. Stability of the plaque
B. Age of the patient
C. Type of activity bringing on chest pain
D. Pain has never had chest pain before
A. Stability of the plaque
Question:
Which category of beta blockers inhibit both beta 1 and beta 2 receptors?
A. Selective beta blockers
B. Non-selective beta blockers
B. Non-selective beta blockers
