Ischemic Heart Disease I Flashcards
What are the risk factors for development of coronary atherosclerosis?
Treatable => reduced risk:
- Smoking
- HTN
- Dyslipidemia
Treatable, no clear risk reduction w/ tx
- Diabetes/insulin resistance
- Obesity
- Inflammation
- Psych stress
- Sedentary lifestyle
Not treatable
- Males
- Age
- Most genetic factors
Which body response exacerbates almost all of the risk factors? He addressed this a bunch in his lecture
Inflammation!!!
However steroids have not been shown to reduce CHD (lots of trials going on now to see if/which specific ones will work)
What are the distinguishing features of the coronary circulation, including principle determinants of myocardial oxygen supply and demand?
1) Myocardium depends on aerobic metabolism for energy supply
2) Resting => near-maximal amount of O2 is extracted from coronary arterial blood (only way to ^ O2 supply is to ^ flow rate)
3) LV is perfused in diastole only
What are the key elements of pathophysiology stable coronary heart disease that decrease the O2 supply?
1) Perfusion pressure
2) Diastolic time
3) Coronary resistance
4) O2 content
Describe perfusion pressure as a key element of pathophysiology stable coronary heart disease.
a
Describe diastolic time as a key element of pathophysiology stable coronary heart disease.
- LV perfusion is diastolic b/c of compression of intramural coronary vessels in systole
- ^ HR shortens cardiac cycle (mostly shortens diastole)
- THEREFORE => tachy can compromise coronary flow
Describe coronary resistance as a key element of pathophysiology stable coronary heart disease.
a
Describe decreased O2 content as a key element of pathophysiology stable coronary heart disease.
a
What is the tx of perfusion pressure?
Prevent hypotension
What is the tx of impaired diastolic time?
Rate-slowing drugs (e.g. beta blockers)
This is increases diastolic filling time
What is the tx of coronary resistance?
Vasodilators
- Nitrates
- CCBs
- Coronary angioplasty
- Bypass surgery
What is the tx of decreased O2 content?
Treat anemia and hypoxemia
What are the key elements of pathophysiology stable coronary heart disease that increase the O2 demand?
1) Increased HR
2) Wall tension (think Law of LaPlace)
3) Inotropic state
What is the tx of increased HR?
Rate slowing drugs
- Beta-blockers
- CCBs
What is the tx of increased wall tension?
Limit LV cavity size by limiting excessive preload
- Diuretics
- Nitrates
What is the tx of increased inotropic state (contractility)
Negative inotropes
- Beta-blockers
- CCBs
Describe pathophysiology unstable coronary heart disease.
- Inflammation in arterial wall
- Weakening of fibromuscular cap
- Abrupt plague fissure/rupture
- Thrombogenic components in blood (lipids, TF)
- Thrombosis w/ partial or complete occlusion
- Myocardial injury and/or necrosis
- Cardiac dysfunction, risk of arrhythmias, death
Describe the pathophysiology of unstable angina
- Near/complete vessel occlusion w/ thrombus
- “threatened” heart attach
- Biomarkers (troponin) are NEGATIVE
- May not cause myocardial damage if tx is successful
- ^ risk of recurrent events in 1st yr
Describe the pathophysiology of MI
- Persistent/severe coronary flow reduction
- Thrombus => complete vessel occlusion
- Wavefron of necrosis
- Biomarkers are elevated
- Cardinal symptoms (but 30% of symptoms are silent)
- Early reperfusion is key tx
- ^ early mortality if you don’t go to the hospital
- Late mortality related to extent of LV dysfunction
What is the timeline of acute coronary occlusion?
W/in minutes:
- diastolic dysfunction
- Systolic dysfunction
- ECG signs of MI
- Symptoms (chest pain, dyspnea, arrhythmias)
W/in an hour
- necrosis and infarction
Go look at the slide for this one (has more details)
