module 5: cardiovascular disorders Flashcards
what is atherosclerosis?
principally a disease in the tunica intima of arteries that results in increased wall thickness, decreased elasticity, reduced vessel radius (flow), reduced flow rate, and ischemia to supplied organ/tissue
- fibrous fatty lesions form in large/medium-sized arteries
- aorta
- femoral
- carotid
- coronary
describe the anatomy of a atherosclerotic plaque
- aggregation of smooth muscle cells
- macrophages
- other leukocytes
- elaboration of extracellular matrix
- collagen
- elastic fibers
- intracellular/extracellular lipids
- aggregation of smooth muscle cells
- macrophages
- other leukocytes
- elaboration of extracellular matrix
- collagen
- elastic fibers
- intracellular/extracellular lipids
what is the effect of atherosclerosis on the blood vessel wall thickness and elasticity, and on the rate of blood flow?
- increased wall thickness
- decreased elasticity
- reduced vessel radius → reduced flow rate
- ischemia to supplied organ/tissue
which four general blood vessels are principally affected?
- aorta
- femoral
- carotid
- coronary
describe the steps involved in the development of atherosclerosis
- rated to endothelial cell damage
- hyperlipidemia, cigarette smoke, immune mechanisms, turbulent blood flow, etc. can result in:
- increased endothelial cells permeability= substances can move into damaged cells = buildup of plasma proteins/lipids
- monocytes and other leukocytes come into the subendothelial layer due to the buildup of proteins and lipids (follows them into cells)
- monocytes turn into macrophages to ingest lipid and turn into lipid foam cells
- macrophages release growth factors to reproduce smooth muscle and reactive oxygen species, and other toxic substances
- progressive tissue damage and growth of plaque lesion
what is the significance of low-density lipoproteins to atherosclerosis?
associated with atherosclerotic plaques
- high levels of LDLs are associated with damage of endothelial lining and depositing underneath = coronary artery diseases as a result of atherosclerosis
- inflammatory reaction that’s going to cause plaque formation
- LDLs are oxidized by ROS in plaques and then phagocytized by macrophages = an even bigger buildup of foam cells
name some predisposing risk factors for atherosclerosis
- elevated cholesterol
- high blood pressure increase endothelial cell damage
- obesity
- diabetes
- smoking
- sedentary lifestyle
what is coronary artery disease (CAD)?
- ischemic heart disease = blocking blood flow to heart
- cause of ischemic heart disease
- third of all deaths in industrialized west
- nearly all elderly have some coronary impairment
what is ischemic heart disease (IHD)?
a disease characterized by ischemia (reduced blood supply) of the heart muscle, usually due to coronary artery disease (atherosclerosis of the coronary arteries)
- heart muscle not getting enough blood for tissue to work properly
describe the relationship between coronary artery disease and ischemic heart disease
since coronary artery disease is the major cause of ischemic heart disease, the two terms are often used interchangeably
Which regions of the heart are affected by blockages in the right coronary, and vessels leading from the left coronary arteries? (You don’t need to separate out the regions from the individual vessels leading from the left coronary artery.)
- right coronary:
- supplies mostly the right ventricle and posterior regions of the heart
- blockage between right and left ventricle
- left coronary arteries:
- supplies mostly the left ventricle and interventricular septum
- blockage of upper right left ventricle and lower left ventricle
Describe the mechanisms that regulate myocardial blood flow and identify when myocardial blood flow is the highest.
- in strenuous exercise, coronary blood flow increases 3-4x
- nervous control
- autonomic control
- local autoregulatory control
- blood flow highest during diastole
describe the autonomic control of myocardial blood flow
- parasympathetic via vagus nerve
- sympathetic:
- alpha receptors = constrict
- beta receptors = dilate
describe local autoregulatory control for myocardial blood flow
local metabolism is a major control of myocardial blood flow
- in local environment, metabolism can activate vasoactive mediators
- vasoactive mediators produce vasodilation or constriction depending what those mediators are, to meet demand of heart
- ex: adenosine and nitric oxide
Why is the subendocardial region of cardiac muscle most sensitive to ischemia?
they have most difficulty obtaining adequate blood flow
Why is the collateral circulation of the myocardial blood flow a potential life-saving feature?
- there are many connections called anastomoses between smaller. coronary arteries
- during acute ischemia, anastomoses dilate fast to shunt blood to an alternative path to help bring blood to heart when there is another blockage
Define angina pectoris and differentiate between stable angina and unstable angina
- angina pectoris: chest pain from a gradual hardening and narrowing of the coronary arteries
- can lead to complete occlusion (blockage) = myocardial infarction
- stable: chest pain caused by transient myocardial ischemia
- not severe enough to cause necrosis
- unstable: atherosclerotic plaque still in coronary artery and small portions of the plaque can break off (thromboses) and move through circulation = periods of occlusion
describe the underlyng pathology of stable angina
- transient myocardial ischemia
- brought on through physical exertion/emotional stress
- myocardial blood flow cannot responf to increased demand for blood due to narrowing of one or more coronary arteries by atherosclerotic plaque
describe the underlying pathology of unstable angina
- atherosclerotic plaque sheds and leads to a development of small thromboses = periods of occlusion
describe the distinctive diagnostic clinical features of stable angina regarding: the pattern and duration of pain
- pain radiates from the sub-sternal regian of the chest to the jaw and down the arms
- symptoms last less than 15 minutes
describe the distinctive diagnostic clinical features of stable angina regarding: the effect of exercise and emotional strss on the signs/symptoms
pain brought on through physical exertion/emotional stress
describe the distinctive diagnostic clinical features of stable angina regarding: the effect of short acting vasodilators such as glycerol trinitrate (GTN) on the signs and symptoms
symptoms relieved by GTN vasodilator
describe the distinctive diagnostic clinical features of unstable angina regarding: the pattern and duration of pain
- chest pain is sudden and unpredictable
- pain generally more severe, lasting longer than 20 minutes
describe the distinctive diagnostic clinical features of unstable angina regarding: the effect of exercise and emotional stress on the signs/symptoms
chest pain is not in response to exertion or stress, but is spontaneous
describe the distinctive diagnostic clinical features of unstable angina regarding: the effect of short acting vasodilators such as glycerol trinitrate (GTN) on the signs and symptoms
requires immediate hospitalization for rest, observation, and treatment: nitrates (vasodilator)
what is acute coronary syndrome?
a spectrum of ischemic heart diseases ranging from unstable angina to myocardial infarction
describe the differences in underlying pathology of acute coronary syndrome regarding: unstable angina
- atherosclerotic plaque is still in the coronary artery
- small portions of the plaque can break off = small thromboses
- small thromboses move through circulation = blockages in blood vessels
describe the differences in underlying pathology of acute coronary syndrome regarding: non-ST segment myocardial infarction (Non-STEMI)
sometimes thrombus disintegrates before complete tissue necrosis = only sub endocardium affected
- don’t see ST elevation because thrombus in blood vessel sometimes disintegrates before complete damage
describe the differences in underlying pathology of acute coronary syndrome regarding: ST-segment elevation myocardial infarction (STEMI)
most serious heart attack
- the clot lodges permanently in the vessel and the entire thickness of the myocardium becomes ischemic
- requires immediate emergency intervention
describe the distinctive diagnostic clinical features for unstable angina regarding: the pattern and duration of pain
- chest pain sudden and unpredictable
- pain generally more severe, lasting longer than 20 minutes
describe the distinctive diagnostic clinical features for unstable angina regarding: whether the event occurs at rest or only as a result of stress
chest pain is not in response to exertion or stress, but is spontaneous
describe the distinctive diagnostic clinical features for unstable angina regarding: the effect of short acting vasodilators such as glycerol trinitrate (GTN) on the signs and symptoms
requires immediate hospilization: nitrate (vasodilator)
describe the distinctive diagnostic clinical features for non-STEMI regarding: the pattern and duration of pain
sometimes thrombus disintegrates before complete tissue necrosis: only sub endocardium affected
- lasts over 20 minutes
describe the distinctive diagnostic clinical features for non-STEMI regarding: whether the event occurs at rest or only as a result of stress
can happen at rest
describe the distinctive diagnostic clinical features for non-STEMI regarding: the effect of short vasodilators such as glycerol trinitrate (GTN) on the signs and symptoms
not relieved by GTN
describe the distinctive diagnostic clinical features for STEMI regarding: the pattern and duration of pain
- serious: requires immediate emergency intervention
- duration over 20 minutes
describe the distinctive diagnostic clinical features for STEMI regarding: whether the event pccurs at rest or only as a result of stress
pain occurs at rest
describe the distinctive diagnostic clinical features for STEMI regarding: the effect of short acting vasodilators such as GTN on the signs and symptoms
not relieved by GTN
Describe the ECG changes related to myocardial infarction and distinguish between STEMI and Non-STEMI ECG traces.
- non-STEMI: sometimes transient ST elevation, the T wave inversion
- STEMI: ST segment elevation on ECG
what are serum cardiac biomarkers?
markers produced when there’s nectrotic tissue
- if seen in lab, it means there’s necrotic tissue going on
- ex: troponin T
Describe the changes in serum cardiac biomarkers in relation to myocardial infarction and how these are used to differentiate MI from unstable and stable angina.
- both Non-STEMI and STEMI present cardiac biomarkers
- different MI to angina since biomarkers are able to distingush necrotic tissue
Describe the usual manifestations of ACS
- abrupt onset
- severe and crushing pain, usually substernal, radiating to the left arm, neck, or jaw
- gastrointestinal complaints
- complaints of fatigue and weakness
- tachycardia, anxiety, restlessness, feelings of doom
- pale, cool, and moist skin
- a “silent MI” occurs when the person is asymptomatic
what are atypical symptoms of ACS?
- GI complaints
- complaints of fatigue and weakness
- tachycardia, anxiety, restlessness, feelings of doom
- pale, cool, and maist skin
what does the term “silent MI” mean?
occurs when a person doesn’t experience any symptoms or has atypical symptoms
identify the three main causes of death through myocardial infarction. Which one is the most common cause of death?
- decreased cardiac output
- fibrillation of the heart
- rupture of the heart
most common cause of death: VF = ventricular fibrillation
describe decreased cardiac output
decreased cardiac output → cardiogenic shock
- pumping ability reduced
- maybe exacerbated by “systolic stretch” = dead muscle
- when the heart goes to contract, there’s dead muscle= no contraction = bulge & pooling of blood
- when cardiac output is inadequate to the needs of tissues heart failure and peripheral ischemia result = cardiogenic shock
describe fibrillation of the ventricles after MI
- main cause of death in STEMI is VF = ventricular fibrillation
- cardiac output is zero
- due to erratic electrical impulses and abnormal conduction pathways in damaged myocardium
- dangerous periods of VF to occur are after first 10 minutes then after 1 hour or so
describe rupture of the infarcted area
- can occur several days after infarct as muscle fibres necrose and degenerate and the heart wall stretches thin
- systolic stretch increases to the point when finally the heart ruptures
- one way of assessing severe MI is by cardiac imaging to monitor the degree of systolic stretch
List the measures involved in immediate care of ACS.
- nitroglycerin (GTN)- fast acting vasodilator
- bed rest
- pain relief - morphine
- 12 lead ECG and ECG monitoring
- oxygen therapy - to increase oxygen
- beta blockers - slows HR, lengthen diastole
- beta adrenergic receptor antagonists
- anticoagulant therapy
Describe the key aspects of care and their rationale
less strain on the heart
- cellular death determines by:
- degree of ischemia due to infarct
- workload on the heart since it increases O2 demand
- lower workload = lower injury from ischemia
- when the heart becomes highly active, coronary arteries dilate to supply healthy muscles with O2 and nutrients
* this reduces collateral circulation that may be assisting the damaged muscle during recovery = not good
describe the importance of pain relief for ACS management
- normally we cannot “feel” our heart - but ischemic myocardium can produce severe “crushing” pain
- believed to releate to release of lactic acid (anaerobic respiration) and mediators of inflammation
- ex: histamine, kinins
- pain rrlief in itself is important for comfort, but also because pain increases stress = cardiac output = increase workload on the heart
Describe the clinical manifestations that occur with atherosclerosis of the aorta
- in large vessles, thrombus formation could lead to hypertension or emboli and weakening of the vessel wall could lead to aneurism
- in smaller blood vessels, can also get weakening of vessel wall = bursting of wall (on top of thrombus/emboli)
Describe the clinical manifestations that occur with atherosclerosis of the cerebal arteries
in medium-sized arteries, mainly ischemia and infarction due to vessel occlusion
- coronary = heart attack
- cerebral - stroke
Describe the clinical manifestations that occur with atherosclerosis of the peripheral arteries
can cause significant pain and disability
- especially prevalent in diabetics
Describe the clinical manifestations that occur with atherosclerosis of the coronary arteries
CAD (coronary artery diseasse) caused by atherosclerosis is the major cause of myocardial ischemia
Define hypertension and identify medical conditions that someone with hypertension may be at increased risk for.
- hypertesion = a consistent elevation of systematic arterial blood pressure
- >/= 140/90
- increased risk for MI, kidney disease, and stroke
- commonly divided into categories of primary (idiopatheic) or secondary (resulting from another disorder)
Are most cases of hypertension due to primary or secondary causes?
primary (95%) due to a combination of genetics and the environment
What factors can lead to primary hypertension?
- family history
- age
- gender
- race
- high dietary sodium intake
- insulin resistance
- cigarette smoking
- obesity
The increase in blood pressure is due to one or both of what 2 changes in the circulatory system?
- increase in circulating blood volume (volume of blood gone up)
- increased peripheral resistance (blood vessels are constricted/extra resistant to the amount of blood coming in)
describe 3 factors that can interact to produce changes to blood pressure
- sympathetic nervous system - increases heart rate and vasoconstriction
- overactivity of renin-angiotension-aldosterone system (RAAS) - increases blood volume and pressure (retain water in kidneys), increases vasoconstriction
- chronic inflammation results in smooth muscle contraction
Why is hypertension called the “silent disease”? Give examples of damage that can be caused by sustained hypertension
- “silent disease” = early stages have no symptoms/signs, other than elevated blood pressure
- damage due to sustained hypertension:
- coronary heart disease
- kidney disease
- CNS dysfunction (stroke)
- impaired vision
How is hypertension diagnosed and how is it typically treated?
- diagnosis:
- several BP measurements at different times
- 3-5 visits depending on the measurement
- complete blood count (CBC)
- urinalysis
- blood chemistry
- ECG
- several BP measurements at different times
- treatment:
- exercise
- lose weight
- stop smoking
- diuretics
- other antihypertensives
Describe the two classifications of hypertension during pregnancy
- pre-existing: present before pregnancy, or appears before 20 weeks of pregnancy
- gestational: occurs at or after 20 weeks of pregnancy - due to the pregnancy
Why would hypertension develop during pregnancy and be familiar as to what conditions it might lead
- unknown: thought to be due to a decrease in placental blood flow = release of toxic compounds that causes changes in blood vessel walls throughout the body
- conditions: risk for development of many pathological effects
- preeclampsia = danger zone
- liver failure
- kidney failure
- heart disease
- respiratory distress
- DIC
- generalized edema