CLASS 21 - ISCHEMIC HEART DISEASE Flashcards
Which 2 coronary arteries does the myocardium recieve blood from?
L + R
Which 2 arteries does the Left Main Coronary Artery branch into?
Circumflex
Left Anterior Descending
What 2 areas of the heart does the LAD supply blood to?
Circumflex artery?
LAD: LV and septum
Circumflex: Lateral + posterior LV
What areas of the heart does the Right Main coronary artery and its branches supply blood to?
Anterior + posterior right vetricle
SA/AV nodes
What ares of the heart does the posterior descending artery supply blood to?
inf + apex of myocardium
When the heart rate or metabolic rate increases such as during exercise, smooth muscle in the arterioles supplying the heart muscle _______ causing _________ and increased blood flow.
relaxes
vasodilation
What are the 3 causes of local dilation in the smooth muscle of the arterioles supplying the heart?
1) metabolites
2) B-adrenergic stimulation (SNS reponse)
3) Release of NO from vascuar endothelium
Why does the heart muscle receive blood during diastole?
due to the high pressure during systole.
This is acheived by the aortic recoil which aids perfusion into the coronary arteries.
What is the effect of a high heart rate on diastolic time?
High HR decreases diastolic time.
Decreases the perfusion time of the coronary arteries which may contribure to ischemia in an individual w narrowed coronary arteries.
What is the most common form of heart disease?
CAD, also called IHD
What is the most common cause of CAD?
Atherosclerosis
What is an atheroma?
a fatty, fibrous mass, or a plaque
at what age does plaque formation usually begin in the body?
In your 20s.
the process of atheroslcerosis is usually asymptomatic until when? What symptoms show at this point?
asymptomatic until a vessel is 75% occluded.
at this time the heart shows signs of ischemia particularly during high times of physical exertion when the metabolic demand is higher.
What is collateral circulation?
additional arterial connections that can form around an area of increasing occlusion / blockage
What are the 9 clinical manifestations of CAD?
Chronic Stable Angina
Acute Coronary Syndrome
- Unstable Angina
- Acute MI
- Non-STEMI
- STEMI
Cardiac Arrhythmias
Heart Failure
Sudden Cardiac Death
when can ischemia occur at rest?
when lumen reduced by 90%
Describe the effects of a MI at a cellular level .
What happens if the blood flow returns in time?
myocardium hypoxic within first 10 seconds of blockage
total occlusion - contractility stops after several minutes
anaerobic metabolism begins
- lactic acid accumulates
- pain fibers stimulated
- crossover –> referred pain –> left shoulder and arm
cardiac cells begin dying ~ 20 mins
IF blood flow returns in time, process reverses, contractility restored and repair begins
Identify the 5 possible effects of Cardiac Ischemia
1) Diastolic Dysfunction
2) Systolic Dysfunction
3) Electric disturbance in heart rhythm
4) Angina pectoris (chest pain)
5) Cardiac muscle death (necrosis), MI
What is angina? Where is the pain typically located? What is the pain sensation often described as?
angina is chest pain resulting from reversible myocardial ischemia
pain typically located in substernal region and may radiate to the arm
visceral + referred pain
pressure, aching, heaviness, choking, suffocating, or squeezing
what are the 4 typical presentations of angina?
1) midsternal, neck, L shoulder and down both arms
2) substernal radiating to neck and jaw, radiating down left arm
3) epigastric, radiating to neck, jaw, and arms
4) intrascapular
describe stable angina in terms of how long it lasts, what causes it and induces it, and how we can control it.
- thought to be caused by an advanced plaque that is hightly fibrotic and contains little lipid (stable)
- usually brief (3-5 mins), relieved by rest and / or nitroglycerine (which causes vasodilation)
- may be induced by specific levels of activity
- can often be controlled with medications
what is the effect of Stable Angina on an ECG?
ST depression
What is prinzmetal’s angina (variant angina)?
what causes it? when does it occur?
occurs at rest due to coronary artery spasm
may occur w or w/o coronary artery disease (can occur if someone has a history of migraines or raynaud’s phenomenon)
may be in response to a stimulant
Describe Acute Coronary syndrome and its 3 components
when does it typically occur?
acute coronary syndrome develops when myocardial ischemia is prolonged and not immediately reversible.
- unstable angina
- non-STEMI (non ST-segment elevation myocardial infarction)
- STEMI (ST-segment elevation myocardial infarction)
Typically occurs when a coronary artery is greater than 90% occluded.
Describe Unstable Angina as an Acute Coronary Syndrome.
rupture of plaque with subsequent coronary vasoconstriction and occlusive thrombus formation.
This is followed by spontaneous thrombolysis (resolves it)
requires immediate hospitalization
identify the 3 clinical manifestations of unstable angina
1) chest pain - onset, duration, and intensity of symptoms lasting up to 20 minutes and is not relieved by rest or nitroglycerine
2) dyspnea - may occur due to myocardial cysfunction and pulm edema
3) reduced CO may occur bc of systolic dysfunction
what are the 5 typical progressions of angina?
1) angina that develops w less exertion
2) angina at rest or during sleep
3) angina pain that isn’t relieved properly w nitroglycerine but once was
4) angina that gradually worsens over a period of days
5) cardiac biomarkers remain normal or are only very minimally elevated.
how can a ventricle become “stunned”?
Ventricle can become stunned if ischemia is persistent but lasts less than 30 minutes
Results in mild decrease in ventricular function that can last for weeks.
if blood flow is not restored within ____ to ____ minutes, cardiac cells begin to die, resulting in permanent myocardial dysfunction.
40 - 60 minutes
