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coronary artery disease
coronary heart disease
what is CHD
characterized by insufficient delivery of oxygenated blood to the myocardium due to atherosclerotic coronary arteries
sequelae of CHD:
- angina pectoris
- -myocardial infarction
- -sudden cardiac death
etiology of CHD
- atherosclerosis causes narrowing of arterial lumen that can lead to cardiac ischemia thru:
- -thrombus formation
- -coronary vasospam
- -endothelial cell dysfunction
mechanisms of coronary atherosclerosis
- lipids are transported via apoproteins
- -lipoproteins associated with a greater risk of atherosclerosis
- -high-density lipoproteins transport cholesterol from peripheral tissue back to the liver, clearing atheromatous plaque
mechanisms of coronary atherosclerosis
- atherosclerotic plaque formation initiated by injury to coronary artery endothelium
- -endothelium becomes permeable and recreuits leukocytes
- -LDL insudation occurs with oxidation by endothelial cells and macrophages
- -oxidized lipids are damaging to endothelia and smooth muscle cells, and stimulate recruitment of macrophages to vessel
- -macrophages engulf the lipids; foam cells release inflammatory mediators and growth factors, attracting more leukocytes and stimulate smooth muscle proliferation
- -excess lipid and debris accumulate w/in vessel wall and coalesce into lipid core
vulnerable plaques may rupture/become eroded, which stimulates clot formation on plaque
what does vulnerable plaques have?
- -large lipid core
- -thin cap
- -high shear stress
what is the pathophysiology of ischemia
occurs when oxygen supply is insufficient to meet metabolic demands
what critical factors in meeting cellular demands for oxygen include?
- rate of coronary perfusion
- -myocardial workload
How can coronary perfusion be altered?
- atherosclerotic plaque
- -acute platelet aggregation and thrombosis
- -failure of autoregulation by microcirculation
- -poor perfusion pressure
- -can be reversible if short-lived or treated appropriately
What are the clinical features and management of coronary syndromes
- Chronic syndromes with slow progression due to chronic obstruction from stable atherosclerotic plaques
- -Acute coronary syndrome associated with acute changes in plaque morphology and thrombosis
ACS stands for?
Acute coronary syndrome
Acute coronary syndrome means...
- unstable angina
- -myocardial infarction
Chronic syndromes with slow progression means...
- stable angina pectoris
- -ischemic cardiomyopathy
what is angina pectoris?
- chest pain associated with intermittent myocardial ischemia
- -may result in inefficient cardiac pumping w/ resultant pulmonary congestion and shortness of breath
What are the 3 patterns of angina pectoris
- -stable/typical angina
- -prinzmetal/variant angina
- -unstable or crescendo angina
What is Acute Coronary Syndrome?
- Chest pain usually more severe and lasts long than typical angina
- -plaque rupture w/ acute thrombus development
- -unstable angina - occlusion is partial
- - MI - occlusion is complete
- -ECG and bio markers used for diagnosis
what does a MI in acute coronary syndrome do to the CO?
- leads to drop in CO, triggers compensatory responses including sympathetic activation, which increased myocardial workload by increasing the following:
- -heart rate
in acute coronary syndrome, sympathetic NS activation leads to an increase or decrease myocardial, and what increases it?
- 1) heart rate
- 2) contractility
- 3) bp
What is sudden cardiac death
- unexpected death from cardiac causes w/in 1 hr of symptom onset
- -use of external defibrillators and CPR increases survival
what is usually the primary cause of sudden cardiac death?
What is chronic ischemic cardiomyopathy?
- heart failure develops insidiously due to progressive ischemic myocardial damage
- -typically have history of angina or MI
- -commong in older adults
What causes damage to the endocardial and valvular structures?
- -inflammation and scarring
- -congential malformations
- (cause altered hemodynamics of heart and ^myocardial workload)
What is stenosis? An example?
- failure of the valve to open completely results in extra pressure work for heart
- ex: IHSS - Idiopathic Hypertrophic Sub-aortic Stenosis
What is regurgitation?
inability of a valve to close completely results in extra volume work for the heart
What is mitral stenosis?
- blood flow from L atrium to L ventricle is impaired during ventricular diastole
- -^pressure of L atrium leads to atrial chamber enlargement and hypertrophy
- -low-pitched, rumbling diastolic murmur
What can mitral stenosis lead to?
- chronic pulmonary hypertension
- -R ventricular hypertrophy
- -R sided heart failure
what is Mitral Regurgitation
- backflow of blood from the L ventricle to L atrium during ventricular systole
- -L atrium and ventricle dilate and hypertrophy due to extra volume
- -high-pitched, pansystolic, blowing murmur
What can mitral regurgitation lead to?
L-sided heart failure
What is mitral valve prolapse?
- displacement of mitral valve leaflets into L atrium during ventricular systole
- -midsystolic click or systolic murmur
What kind of complications involved with mitral valve prolapse
- infective endocarditis,
- sudden cardiac death,
- cerebral embolic events
- progression to mitral regurgitation
What is aortic stenosis?
- results in obstruction of aortic outflow from L ventricle to aorta during systole
- -crescendo-decrescendo murmur during ventricular systole with prominent S4
What is the predominant cause of aortic stenosis? and what may result from it?
- age related calcium deposits on aortic cusps
- -may result in ischemia and L-sided HF
what are the disease of endocardium?
- rheumatic heart disease
- -infective endocarditis
what is rheumatic heart disease?
- acute inflammatory disease that follows infection with groups A β-hemolytic streptococci
- -antibodies against this antigen damages the connective tissue in joints, heart and skin
- -mainly in children
what is infective endocarditis
- invasion and colonization of endocardial structures by microogranisms w/ resulting inflmaation-vegetations
- -predisposing risk factors present
what bacteria commonly causes infective endocarditis
what is myocarditis
- inflammatory disorder of heart muscle characterized by necrosis and degeneration of myocytes
- -cardiomyopathy may be genetic OR acquired and is noninflamatory
What causes myocarditis and what is characterized by it?
- causes + microbial agents, immune-mediated disease, physical agents
- -viral etiology - common
- -characterized by L ventricular dysfunction and general dilation of all 4 chambers
How is cardiomyopathy classified? How many types and name it.
- by cause/functional impairment
- Primary: dysfunction of unknown cause
- secondary: known cause
dilated, hypertrophic, restrictive
What is dilated cardiomyopathy? what relates to it?
- cardiac failure associated with dilation of one or both ventricular chambers
- -slow progression of biventricular HF with low ejection fraction
- -related to: alcohol toxicity, pregnancy, postviral myocarditis, genetic abnormality
What is hypertrophic cardiomyopathy?
- thickened, hyperkinetic ventricular muscle mass
- -septum my be affected
- -genetic abnormality
- -slow progression
what might hypertrophic cardiomyopathy lead to?
IHSS - idiopathic hypertrophic subaortic stenosis
What is restrictive cardiomyopathy?
- -rare form of cardiomyopathy
- -stiff, fibrotic ventricle with impaired diastolic filing
- -associated with amyloidosis
- -decreased CO and L-side HF can result