Exam 3: The Heart Pt2 Flashcards
What is a general term that involves any situation involving myocardial injury following myocardial ischemia?
Ischemic Heart Disease (IHD)
How fast will significant ischemia cause cardiac dysfunction? What about a myocardial infarction?
dysfunction –> w/in 1-2 minutes
M.I.–> w/in 20-40 mins
What do most cases (90%) of Ischemic Heart disease develop following?
coronary artery disease = the presence of atheromas within the coronary arteries
We know CAD causes 90% cases of Ischemic Heart Disease, what can cause the other 10%?
- Reduced Coronary artery blood flow (90%)
- increased cardiac demand for blood/oxygen
- a reduction in total blood volume
- a reduction in red blood cell oxygenation
- diminished oxygen-carrying capacity
What related pathologies may cause the “reduced coronary artery blood flow” that may cause Ischemia Heart Disease?
- coronary artery disease
- distributive forms of shock
What related pathologies may cause the “increased cardiac demand for oxygen” that may cause Ischemia? Heart Disease?
- HTN
- Tachycardia
What related pathologies may cause the “reduced blood volume” that may cause Ischemia? Heart Disease?
hypovolemic shock
What related pathologies may cause the “reduced oxygenation” that may cause Ischemia? Heart Disease?
- pneumonia
- COPD
- congestive heart failure
What related pathologies may cause the “reduced oxygen-carrying capacity” that may cause Ischemia? Heart Disease?
- acute carbon monoxide poisoning
- severe anemia
What is it called when 70% or more of the available cross-sectional diameter of a coronary artery is occluded?
critical stenosis–> now become symptomatic
What will one experience who has Critical stenosis of a coronary artery?
- chest pain = angina pectoris; that is provoked by physical activity
- if at rest and have symptoms = 90% occlusion
What is the most common reason for a sudden (acute) myocardial infarction to occur?
acute plaque change of a coronary artery atheroma
What are teh cardiac syndromes that Ischemic Heart Disease may manifest as, regardless of what caused it?
- angina pectoris
- myocardial infarction
- sudden cardiac death or chronic ischemic heart disease/CHF
What are the three forms of Angina Pectoris?
(aka “chest pain”)
- Stable Angina
- Prinzmetal Angina
- Unstable Angina
T/F. The level of ischemia associated with angina pectoris is sufficient enough to cause pain and myocyte death.
False—yes it can cause pain, but it does NOT cause myocyte death
What is the typical pain distribution of angina pectoris? How is the pain described?
chest, neck, jaw, left shoulder/arm, and epigastric region
as “crushing” or “squeezing” sensation, freq ass. with dyspnea, nausea, and sweating
What involves episodic angina pectoris that is predictably stimulated by increase in physical activity?
Stable angina
What is the pain associated with Stable Angina described as? Where does it typically go? How is the pain relieved?
“crushing” or “squeezing”
substernal or radiating into left jaw, neck, and arm
relieved by rest or with vasodilatory medications
What angina type occurs at rest and is the result of coronary artery vasospam?
Prinzmetal angina (aka variant angina)
What are the risk factors for coronary artery vasospasm associated with Prinzmetal Angina?
- atherosclerotic plalques (CAD)
- vascular inflammation
- SNS stimulation
Does Prinzmetal angina respond to vasodilatory medications?
yes
When are myocardial infractions highest during the day? why?
b/w 6am and noon
think due to surge of adrenergic stimulation that occurs with awakening
What occurs in patients that have a history of stable angina, but are experiencing an increasing severity of their signs and symptoms?
Unstable Angina
What will Unstable Angina characteristically produce?
angina that is increasing in frequency, intensity, and is provoked by less exertion of may even develop at rest
In what people is Unstable angina most likely to develop in?
patients who develop critical stenosis and freq ass. with development of an acute plaque change or thromboembolism
What describes ischemia necrosis of myocardial cells?
myocardial infarction (MI, acute myocardial infarction, or heart attack)
What are the vast majority of M.I.s caused by?
acute thrombosis w/in coronary artery at sites of preexisting atherosclerotic plaques
What are risk factors for developing a myocardial infarction?
- HTN
- male sex
- post-menopausal females
- cardiac amyloidosis
- family Hx
- smoking
- sickle cell anemia
- obesity or metabolic syndrome
- diabetes mellitus
- advanced age
- hypercholesterolemia
- type A personality (stress)
What is the most commonly involved artery to cause a myocardial infarction and is associated with nearly 50% of all M.I.s?
left anterior descending (LAD) artery
What is the left anterior descending (LAD) artery considered as? why?
the “widow maker”–> b/c is ass. with 50% of all M.I.s
Where is a myocardial infarction most likely to develop and where will it spread to?
first develop at subendocardial zone of heart wall and proceed externally to involve the entire thickness of the cardiac wall
Following what, may reperfusion of blood supply to ischemic myocardium occur?
- enzymatic thrombolysis (tPA or tissue plasminogen activator)
- coronary artery angioplasty and endovascular stent placement
- placement of bypass graft
Reperfusion of blood to previously ischemic myocardium may result in significant myocardial dysfunction, what may this cause?
- increased oxidative stress
- mitochondrial dysfunction
- myocyte hypercontracture
- increased platelet and compliment activity
- –> all increasing inflammation and irritability–> put at risk of developing prolonged cardiac arrhythmia (“V-fib”)–> may lead to lethal sudden cardiac death
When dos a M.I. start to show gross cellular changes?
12-24 hrs–> grossly red-blue discoloration becomes evident
if survive–> lesion becomes well-demarcated w/in 10-14 days ane becomes more fibrotic w/in wks of injury
When will acute inflammatory cells become evident microscopically at the site of M.I.?
When to macrophages become evident?
What happens in 1-2 weeks? What occurs at 6 weeks?
within 1-3 days –> inflam cells
5-10 days–> macrophages are more predominant
1-2 weeks –> area becomes filled with granulation tissue
6 wks–> prominent scar tissue
What are the traditional features of an acute myocardial infarction?
- substernal chest pain–> “crushing” sensation that lasts several mins-hrs
- pain radiates to neck, jaw, epigastric region, or left should and arm
likely to NOT be relieved by vasodilators or rest
How is pain from a M.I. distinguishable from pain associated with angina pectoris?
with a M.I. that pain will most likely NOT subside with vasodilators (nitroglycerine) or with rest
What features besides the pain will inds suffering from a M.I. have?
- dyspnea
- nauseaous
- diaphoretic (sweaty)
- rapid but weak pulse–> “thready”
What will massive M.I.s that involved almost half of the myocardium lead to?
cardiogenic shock
Do women have different features with a M.I.? If so, what?
yes
- nausea
- dizziness
- referred pain to back
- epigastric pain
- pain in lower thorax
- dyspnea
- fatigue
What are the two “cardiac markers” that leak out of necrotic myocardial cellular membranes and enter the blood and help with a M.I. diagnosis?
- Troponins
2. CK-MB
What are the most sensitive and most specific cardiac marker for Dx of a M.I.? When do they become elevated and peak? How long do they remain elevated?
troponins–> become elevated about 4 hours after M.I. and peak around 24-48 hrs
remain elevated for 10 days (longer than CK-MB)
What was historically the cardiac marker for M.I.?
CK-MB
- rise w/in 2-4 hrs of M.I.
- peak around 24 hrs
(MAY allow for a more rapid lab confirmation of recent M.I. over troponins)–but use troponins MC now
What describes the progressive heart failure that develops secondary to ischemia myocardial injury, such as surviving a myocardial infarction or long-term coronary artery disease?
Chronic Ischemic Heart Disease (ischemic cardiomyopathy)
When is Chronic Ischemic Heart Disease said to begin?
when the compensatory mechanisms begin to fail
What may Chronic Ischemic heart Disease involve progessively worsening of?
- angina
- heart failure (contractile failure)
- arrhythmias
- development of M.I.s
What does the morphology of Chronic Ischemic Heart Disease involve?
prominent LV hypertrophy (concentric) and cardiac fragmentation/dilation may occur in advanced stages
What are complicating factors that may worsen the progression of Chronic Ischemic Heart Disease?
- presence of cardiac fibrosis form previous sites of MIs
- cardiac mural thrombi–> embolize due to sluggish blood flow
- coronary arteries contain sig. luminal stenosis –> cause cont myocardial injury
