Cardiac: Ischemic heart disease (IHD) Flashcards
what is the most common cause of ischemic heart disease
atherosclerosis of coronary arteries
what are risk factors for ischemic heart disease
- similar to atherosclerosis
- incidence increases with age
Ischemic heart disease can lead to 1 of the 4 problems in a person
- angina
- myocardial infarction
- Sudden cardiac death
- chronic ischemic heart disease
- Coronary steal syndrome
when does stable angina occur
chest pain with exertion or emotional stress
what causes stable angina
atherosclerosis of coronary arteries with greater than 70% stenosis
what happens to the myocytes in stable angina
reversible injury
-no necrosis
what happens to a person during stable angina and how long does it last
- pain radiates to left arm or jaw, diaphoresis and shortness of breath, chest pain
- less than 20 minutes
what is the EKG reading for stable angina and why do we see that
ST-segment depression due to subendocardial ischemia
what relives stable angina
rest and nitroglycerin
what is unstable angina
chest pain occurring at rest
what usually causes unstable angina
- rupture of an artherosclerotic plaque with thrombosis and INCOMPLETE occlusion of a coronary artery
what happens to the myocytes in unstable angina
reversible injury
- no necrosis
what does the EKG show for unstable angina and why
ST-segment depression due to subendocardial ischemia and/or T wave occlusion
what relieves unstable angina
nitroglycerin
when a patient has unstable angina, they are at a high risk for what
myocardial infraction
what is prinzmetal angina
episodic chest pain unrelated to exertion
- coronary artery vasospasm
what happens to the myocytes in prinzmetal angina
- reversible injury
- no necrosis
what is the EKG reading for Prinzmetal angina and why
ST-segment elevation due to tranmural ischemia
what relieves prinzmetal angina
nitroglycerin
calcium channel blockers
what is myocardial infarction
necrosis of cardiac myocytes
what causes myocardial infarction
- rupture of atherosclerotic plaque with thrombosis and COMPLETE occlusion of a coronary artery ( due to Prinzmetal angina or cocaine use)
- coronary artery vasospasm
- emboli
- vasculitis (kawasaki disease)
what are clinical symptoms for myocardial infarction
- severe, crushing chest pain
- lasts greater than 20 minutes
- radiates to left arm or jaw
- diaphoresis
- dyspnea
what relieves myocardial infarction
not nitroglycerin
myocardial infarction usually involves what part of the heart
left ventricle and right ventricle
- both atria generally spared
occlusion of the left descending artery (LAD) leads to infarction of the?
- anterior wall of left ventricle
- anterior interventricular septum
- apex of heart
occlusion of the right coronary artery (RCA) leads to infarction of ?
- posterior wall
- posterior septum
- papillary muscles of the left ventricle
Occlusion of the left circumflex artery leads to infarction of what?
lateral wall of left ventricle
initial phase of infarction in MI leads to what? what will the EKG look like?
subendocardial necrosis involving less than 50% of myocardial thickness
-ST-segment depression
continued or severe ischemia in MI leads to what? what will the EKG show?
- transmural necrosis involving most of myocardial wall
- ST-segment elevation
what are 2 cardiac enzymes that can be used to detect a MI
Troponin I
CK-MB
what is the most sensitive and specific marker (gold standard) for MI
Troponin I
describe troponin I levels after a MI
rise 2-4 hours after infaction
- peak at 24 hours
- return to normal 7-10 days
What is CK-MB levels good at detecting
reinfarction that occurs days after an initial MI
describe CK-MB levels after a MI
- rise 4-6 hours after infarction
- peak 24 hours
- return to normal by 72 hours
name 6 treatment options for MI and why they are given?
- aspirin/heparin - limits thrombosis
- Supply O2 - minimize ischemia
- nitrates - vasodialates veins and coronary artery
- Beta-blocker- slow heart rate, decrease O2 demand, decrease risk of arrhythmia
- ACE inhibitor - decrease LV dilation
- Fibrinolysis or angioplasty - opens blocked vessel
Reperfusion of irreversibly-damaged cells results in what
calcium influx, leading to hyperconctraction of myofibrils
- contraction band necrosis
when you return oxygen and inflammatory cells to MI cells results in what
- free radical generation, further damaging myocytes
MI: gross change 4-7days
yellow pallor
MI: complications 4-24 hours
Arrhythmias
MI: microscopic changes 1-3 days
neutrophils
MI: gross changes less than 4 hours
none
MI: complications 1-3 weeks
none
MI: microscopic changes 4-7 days
macrophages
MI: gross changes months
white scar
MI: complications 4-7 days
rupture of ventricular free wall
- interventriciular septum ( leads to shunt)
- papillary muscle ( leads to mitral insufficiency)
MI: microscopic changes less than 4-24 hours
coagulative necrosis
MI: gross changes 1-3 weeks
Red border merges as granulation tissue enters from edge of infarct
MI: complications months (3)
- Aneurysm
- mural thrombus
- Dressler syndrome
MI: microscopic less than 4 hours
none
MI: gross changes 1-3 days
yellow pallor
MI: complications 1-3 days
Fibrinous pericarditis ( only in tranmural infarction) -presents as chest pain with friction rub
MI: microscopic 1- 3 weeks
Granulation tissue with plump fibroblasts, collagen, and blood vessels
MI: complications less than 4 hours
- cardiogenic shock ( massive infarction)
- congestive heart failure
- arrhythmia
MI: microscopic months
Fibrosis
MI: gross 4-24 hours
dark discoloration
Coronary steal syndrome
alteration of circulation patterns lead to a reduction in the blood directed to the coronary circulation.
What is sudden cardiac death
- unexpected death due to cardiac disease
- without symptoms or less than 1 hour after symptoms arise
what is the most common etiology of sudden cardiac death
acute ischemia –> ventricular arrhythmia
- in addition, 90% patients have severe atherosclerosis
what are less common causes of sudden cardiac death
- mitral valve prolapse
- cardiomyopathy (dilated/hypertrophy)
- cocaine abuse
- hereditary ion channelopathies (long QT syndrome, Brugada syndrome)
what is chronic ischemic heart disease
poor myocardial function due to chronic ischemic damage (with or without infarction)
chronic ischemic heart disease can progress to what
congestive heart failure
