Unit 2 Flashcards
Identify risk factors for development of coronary atherosclerosis
Treatable:
- smoking (thrombogenic, platelet activation, inc fibrinogen)
- hypertension (inc shear stress –> endo cell injury, pathologic cell signaling, circulating hormones, LVH)
- dyslipidemia (high LDL –> pro-inflamm and atherogenic and low HDL which can be beneficial)
Treatable, but may not reduce risk for CAD:
- diabetes (inc 1.5-2 fold; assoc w/ inflammation, oxidative stress, dyslipidemia)
- obesity
- inflammation (lipid laden macrophages in wall –> pro-inflamm)
- stress
- sedentary lifestyle
Not treatable:
- male
- old age
- most genetic factors
Recognize distinguishing features of the coronary circulation
- myocardium cannot do anaerobic metabolism; depends on aerobic metabolism
- the only way of increasing myocardial O2 supply is to increase blood flow rate
- due to compression of CAs during systole, LV is perfused in diastole
Describe key elements of pathophysiology of stable coronary heart disease
- obstruction in coronary artery limits flow –> myocardial ischemia
- tissue blood flow does not meet O2 reqs especially when demand inc
- imbalance between O2 supply and demand –> ischemia –> angina pectoris
Describe pathophysiology and treatment of unstable coronary heart disease (unstable angina or myocardial infarction)
- inflammation in arterial wall
- weakened fibromuscular cap
- plaque fissure
- lipids and tissue factor exposed to blood –> thrombosis –> severe/complete vessel occlusion –> MI
- cardinal symptom: severe and unremitting chest discomfort at rest
- within minutes, impaired SR reuptake –> diastolic dysfunction –> inc LV filling pressure –> pulm congestion/dedema
- dec high energy phosphates, intracellular acidosis –> systolic dysfunction
- ECG signs
Briefly describe coronary circulation
- aorta gives rise to left coronary artery –> left circumflex artery and left anterior descending artery
- aorta gives rise to right coronary artery –> posterior interventricular in the back
What are principle determinants of myocardial oxygen supply and demand?
Supply:
1) coronary blood flow rate
- perfusion pressure
- perfusion time (1/HR) aka how much time in diastole
- vascular resistance of coronary bed
2) O2 content of blood
O2 delivery = CVF rate * oxygen content
Demand:
1) Heart rate
2) Wall tension (T=P*r/u)
3) Inotropic state
What is autoregulation?
- An adaptive mechanism to maintain perfusion in the face of altered perfusion pressure
- changes in arteriole size to adjust to changes in pressure to maintain flow
- basically, if pressure differential gets bigger, then resistance gets bigger to maintain flow because flow = deltaP/res
Describe treatment for stable coronary heart disease
Treatment:
1) Increasing O2 supply
- inc diastolic perfusion pressure by preventing hypotension
- inc diastolic time with rate-slowing drugs
- dec coronary resistance with vasodilators or coronary angioplasty/bypass
- inc O2 content by treating anemia and hypoxemia
2) Decreasing O2 demand
- dec systolic pressure with antihypertensive drugs
- dec wall tension by limiting LV size by limiting excessive preload (with diuretics and nitrates)
- dec inotropic state to attenuate contractile state (with beta or Ca channel blockers)
Describe the progression of atherosclerosis
normal –> fatty streak (endo injury, lipid deposition, mac/T-cell recruitment) –> fibrous plaque –> occlusive atherosclerotic plaque (activated mac; smooth muscle proliferation forms fibrous cap; lipid accumulation) –> plaque rupture –> angina, MI, stroke
When there is a stenosis, how does autoregulation help?
- stenosis causes a pressure drop
- without autoreg, the pressure drop would result in dec flow because:
flow = deltaP/res
- however, autoreg is able to dilate downstream vessels in response to decreased pressure differential (compared to 0 mmHg at the venous end) so that flow is maintained (dec deltaP/dec res = same flow)
Describe approaches to diagnosis of coronary artery disease
Presentation:
- chest pain
- dyspnea
- risk factors
Physical exam:
- normal
- CV dysfunction prior to MI (CHF)
- atherosclerosis
Tests:
- ECG at rest/changes with exercise (ST segment elev/dep, T wave immersion, Q waves)
- imaging (echo, CT, angiography)
Describe approaches to treatment with medications of CAD
Stable angina:
- nitrates and beta blockers (to decrease demand on heart)
- control BP with anti-hypertensives
- lower cholesterol with statin
- aspirin to prevent thrombi
- ACEi or ARBs for LV dysfunction
Describe approaches to coronary angioplasty and stents
- early coronary angioplasty dec risk of recurrent ischemic events in unstable angina
- balloon dilation of stenosed area –> larger lumen –> dec resistance –> inc flow
- problems: acute occlusion (solve with stents and antiplatelet) and restenosis (solve with stents)
Describe approaches to coronary bypass surgery
- maybe better than angioplasty when multiple blockages
- many types of grafts: internal mammary artery, saphenous vein, prosthetic material
- basically bypassing blockage in LAD (or whatever artery) by connect an artery from left subclavian artery to downstream from the blockage
Describe coronary angiography
- gives an image of the vessel lumen, but does not tell about the vessel wall (underestimates pathologic extent of CAD)
- can diagnose coronary obstruction
- guides angioplasty/surgery
What are the general modes of treatment for CAD?
- modify risk factors (diet, exercise, no smoking)
- drugs to treat angina, BP, lipids, platelets, ACEis/ARBs
- revascularize (angioplasty/bypass surgery)
How do you acutely treat unstable angina?
- hospitalization
- IV nitroglycerin (nitrate = vasodilator)
- beta blocker
- aspirin/anti-platelet
- anticoag
- early catheterization
How do you treat acute MI with ST elevation?
- immediate aspirin, nitroglycerin, maybe beta blocker
- reperfusion therapy ASAP - coronary angioplasty or thrombolytic therapy
Recognize that the normal endothelium is anti-inflammatory, anti-thrombotic, and vasodilatory
Normal endo cells:
- impermeable to large molecules
- anti-inflam
- resists leukocyte adhesion
- promotes vasodilation
- resists thrombosis
Activated endo cells:
- inc permeability
- inc inflam cytokines
- inc leukocyte adhesion
- dec vasodilation
- dec anti-thrombosis
(also activated means activated by inflammation)
Differentiate mechanisms of ischemia depending on the vascular bed, all of which involve endothelial dysfunction
1) Narrowing of vessel by fibrous plaque:
- plaque builds up and you get a stenosis
- seen in renal artery stenosis, myocardial ischemia, limb claudication, and limb ischemia
2) Plaque ulceration/rupture:
- plaque breaks through fibrous cap and have thrombosis
- seen in thrombolic stroke, unstable angina, and MI
3) Intraplaque hemorrhage:
- can have bleeding that occurs within the plaque itself
- seen in thrombolic troke, unstable angina, and MI
4) Peripheral emboli:
- pieces of plaque can break off and get stuck somewhere else
- seen in embolic stroke, atheroembolic renal disease, and limb ischemia
5) Weakening of vessel wall:
- integrity of vessel wall is weakened leading to aneurysm
- seen anywhere
What is the endothelium?
- a single layer of cells comprising tissue that lines blood and lymph vessels, heart, and other cavities
Describe the three layers of the blood vessel wall
- Tunica intima: endothelial cells and CT
- Internal elastic lamina between TI and TM
- Tunica media: smooth muscle cells and CT
- External elastic lamina between TM and TA
- Tunica adventitia: loose CT and provides structure
Describe the contents of the walls of large arteries, smaller arteries, and arterioles
- large arteries: more elastin
- smaller arteries: more collagen
- arterioles: more smooth muscle
Describe the difference between normal and activated smooth muscle cells
Normal SMC:
- normal contractile function
- maintains ECM
- contained in TM
Activated SMC:
- inc inflam cytokines
- inc ECM synth
- migration into subintima
How is NO produced and how does it work?
- receptor on endo cell activated by ACh, serotonin, thrombin, bradykinin or shear stress
- activates eNOS which converts L-Arginine to NO with a lot of cofactors
- NO diffuses to the smooth muscle in TM
- NO causes cGMP mediated vasodilation
- in diseased states where NO is dec –> leads to inflammatory state
Describe the steps in the formation of atherosclerotic plaque
- monocyte infiltration (in an inflammatory state)
- phenotypic change to macrophage
- macrophages get activated and are called foam cells (early sign of atherosclerosis) and secrete cytokines that lead to degradation of endothelium
- changes phenotype of SMC (migrating and dividing uncontrollably)
- increased fibrosis and apoptosis
What are the 3 stages of atherosclerosis?
1) fatty streak:
- endo dysfunction
- lipoprotein entry and modification
- leukocyte recruitment
- foam cell formation
2) plaque progression:
- SMC migration into TI
- altered ECM synth and degradation
3) plaque disruption:
- disrupt plaque integrity
- trombus formation
Compare vulnerable and stable plaques
Stable:
- lots of fibrous tissue
- calcified
- less lipid content
- less inflammation
- less apoptosis
Vulnerable:
- less fibrous tissue
- less calcified
- more lipid content
- more inflammation
- more apoptosis
What are the main mechanisms of stroke?
- atheroembolism (from carotid bifurcation lesion)
- lesion does not need to be completely obstructive (
What are the main vascular mechanisms of CAD?
- MI and angina are results of CAD but have different vascular pathology
- MI: rupture plaque, in-situ thrombosis, doesn’t need to be obstructive prior to rupture
- stabilize with anticoag and vasodilators (if non-occlusive thrombosis)
- clinical emergency/recanalize if occlusive thrombus
- angina: stable, obstructive (>70%) lesion
Describe the potential effects of coronary thrombus
1) small thrombus
- no ECG changes
- healing and plaque gets bigger
2) partially occlusive thrombus
- ST seg depression and/or T wave inversion
- if inc troponin I and other markers –> non STEMI
- if no inc troponin I and other markers –> unstable angina
3) occlusive thrombus
- transient ischemia –> same as partially occlusive thrombus
- prolonged ischemia –> ST elev –> inc troponin I –> STEMI
Describe the vascular pathology differences between claudication and acute limb ischemia as forms of PAD
Claudication:
- obstructive, stable plaque
- analogous to angina
Acute limb ischemia:
- acute event blocks flow
- athero/thromboembolus
- rarely in-situ thrombosis (unstable plaque_
What are the differences generally between stable and unstable plaques?
Stable:
- less bio active
- causes angine and caludication (exertional ischemia) if obstructive
- less likely to be thrombotic and embolic
Unstable:
- more bio active
- can cause MI and stroke
- can be thrombotic and embolic
What are the differences between venous and arterial thrombosis?
Venous:
- fibrin rich
- RBC
- areas of stasis
- genetic predis
- environmental predis
- treat with anticoag
Arterial:
- platelet rich
- plaque rupture
- high flow
- atherosclerosis, trauma, APLA (antiphospholipid antibodies)
- antiplatelet therapy
Describe the spectrum of acute coronary syndrome and its pathophysiology
STEMI
- complete coronary vessel occlusion
NSTEMI
- partial coronary vessel occlusion with myocardial necrosis
Unstable angina
- partial coronary vessel occlusion without myocardial necrosis
Distinguish non-ST elevation myocardial infarction (NSTEMI), ST-elevation myocardial infarction (STEMI), and unstable angina (UA)
STEMI:
- prolonged, severe chest pain
- total occlusion
- inc biomarkers
- ST elevation
NSTEMI:
- prolonged, severe chest pain
- partial occlusion
- inc biomarkers
- ST depression
Unstable angina:
- angina that is escalating, at rest, or new onset
- partial occlusion
- no inc biomarkers
- ST depression
Clinically diagnose acute coronary syndrome based on symptoms, ECG, and biomarkers
ECG:
- subendocardial ischemia shows a ST depression
- transmural ischemia shows a ST elevation
- with a partial occlusion and no infarct, can show ST dep during symptoms and normal when symptom-free (can cause symptoms but not long enough to cause damage)
Biomarkers:
- Troponin I and T are sensitive and specific for myocardium
- rise 3-4hrs after onset of pain
- peak at 18-36hrs
- CK-MB is not as specific for myocardium
- rise 3-8hrs after onset of pain
- peaks at 24hrs
Symptoms:
- angina: chest pain
- stable - pain when inc O2 demand and can reproduce
- unstable - inc in duration, intensity, or frequency; less provocation or at rest; new onset
Explain the basis behind the treatment of ST elevation myocardial infarction
- artery is 100% occluded –> open it with cardiac catheterization if 90min then consider fibrinolytics
- can also give beta blockers or nitrates if stable
Explain the basis behind the treatment of non-ST elevation myocardial infarction and unstable angina
- artery is partially occluded –> stop thrombosis from completely occluding artery with anticoag and antiplatelet
- can also give beta blockers or nitrates if stable
What is the definition of ACS?
Acute Coronary Syndrome is any array of clinical symptoms resulting from underlying acute myocardial ischemia
What are causes of ACS?
- *atherosclerotic plaque rupture with thrombus –> partial or complete thrombosis
- coronary embolism
- congenital anomalies
- coronary trauma or aneurysm
- severe coronary artery spasm
- inc blood viscosity
- spontaneous coronary dissection
- inc myocardial O2 demand
If you have prolonged ischemia, what happens?
- myocyte death and tissue necrosis –> STEMI or NSTEMI
What is the time to initial elevation, time to peak elevation, and time to return to normal for CK-MB?
Time to initial elevation:
- 4-6hrs
Time to peak elevation:
- 18hrs
Time to return to normal:
- 2-4days
What is the time to initial elevation, time to peak elevation, and time to return to normal for troponin I?
Time to initial elevation:
- 4-6hrs
Time to peak elevation:
- 12hrs
Time to return to normal:
- 3-10days
What is the difference between stable and unstable angina?
Stable angina:
- occurs with inc myocardial O2 demand in a reproducible fashion
Unstable angina:
- discomfort which is new in onset OR inc in duration, frequency, or intensity with less exertion or at rest compared to previous episodes of discomfort
- on spectrum of ACS
What is the general goals for treating ACS?
1) relieve ischemia by opening artery and reducing myocardial O2 demand
2) prevent adverse outcomes
What is a differential diagnosis for chest pain?
- ACS/angina
- aortic stenosis/insuff/dissection
- HOCM
- severe HTN
- pericarditis
- GERD
- costochondritis
- PE
- lots of others
Describe the difference between transmural and subendocardial myocardial ischemia
Transmural:
- ischemia spans entire wall of myocardium
- usually due to complete occlusion
Subendocardial:
- involves innermost layer of myocardium
- usually due to partial occlusion
- subendocardial layer has highest pressure from ventricle and smallest collateral flow
Recognize basic concepts and discuss uses of chest x-ray
- on xrays, the higher the density, the whiter the color
- bone is white, tissue is gray, air is black
- PA view minimizes magnification of heart
- also a lateral view
- uses radiation
Recognize basic concepts and discuss uses of echocardiogram
- doppler; ultrasound waves sent into body and returns to transducer
- can show 2D motion
- color doppler of bood flow
- M mode can look at different axis and as a result different chamber sizes
- send microbubbles to visualize a sort of static appearance that don’t pass through pulm caps and don’t show in left heart unless connection between right and left heart
- can look at chamber size, function, structure, valves, etc.
Recognize basic concepts and discuss uses of cardiac stress tests
- cause ischemia by inc O2 demand on heart
- see inc in sys BP and dec in dias BP
- ST dep in ECG
- inc in HR by >85%
- tiredness, dyspnea
- can look at blood flow/perfusion imaging
- can look at wall motion with echo
- good for detecting left main or 3 vessel CAD
- fast for 2hrs before
- monitor ECG, BP, and HR
Recognize basic concepts and discuss uses of cardiac MRI
- 3D imaging
- non-ionizing radiation
- contraindications: metallic implants, kidney dysfunction
Recognize basic concepts and discuss uses of cardiac CT/CT angiography
- noninvasive
- radiation
- doesn’t use catheter
Recognize basic concepts and discuss uses of catheterization/coronary angiography
- insert catheter into artery or vein and move to heart/coronary arteries to image
- measure pressure gradients
- can use contrast for angiography
Differentiate and recognize indications and contraindications for exercise ECG
Exercise Treadmill Test:
1) indications:
- screen for CAD
- eval chest pain
- exercise capacity
- eval after revascularization
2) contraindications:
- unstable angina
- untreated arrhythmias
- uncompensated HF
- AV heart block
- acute myo/pericarditis
- aortic stenosis
- HOCM
- uncontrolled HTN
- acute systemic illness
- low cost
Differentiate and recognize indications and contraindications for echocardiography/radionuclide stress test
Indications:
- abnormal baseline ECG, digoxin, WPW
- inc sensitivity
- localization
- preop cardiac risk assessment
- myocardial viability
Contraindications:
- unstable angina
- untreated arrhythmias
- uncomp HF
- AV heart block
- acute myo/pericarditis
- aortic stenosis
- HOCM
- uncontrolled HTN
- acute systemic illness
Discuss the use of echocardiography in evaluation of patients with shortness of breath, valve disease, chest pain, heart failure, coronary artery disease, and acute coronary syndromes including myocardial infarction
- ultrasound into body and returns to transducer producing a 2D image
Discuss the use of cardiac enzymes in evaluation of patients with shortness of breath, valve disease, chest pain, heart failure, coronary artery disease, and acute coronary syndromes including myocardial infarction
Natriuretic peptides:
- BNP found in ventricles
- released in response to stretch/inc vol in ventricles
- inc BNP = inc LVEDP, NYHA class, HF diagnosis >55yo
- BNP is higher in females and elderly
- BNP inc in renal insuff
The causes of ischemic heart disease and exacerbating factors in coronary atherosclerosis
- ischemic heart disease = syndromes caused by myocardial ischemia when demand>supply
- > 90% of cases are due to coronoary atherosclerosis with reduced coronary blood flow
- symptoms are associated with >70% occlusion
- > 90% can lead to symptoms at rest
- acute changes in plaque morphology (hemorrhage or rupture and/or embolus)
- coronary artery thrombosis
- coronary artery vasospasm
- platelet aggregation
- hypotensive episode
- inc myocardial O2 demand
The pathogenesis of myocardial infarction and differences between transmural and subendocardial infarcts
- irreversible myocyte necrosis due to prolonged ischemia
- most cases caused by acute coronary artery thrombosis due to atherosclerotic plaque rupture
- MIs usually begin in subendocardial region because it is the most poorly perfused then move outwards to become transmural in hours
Transmural infarct:
- full thickness of myocardium; more common and usually due to thrombus in coronary artery
Subendocardial infarct:
- affects inner third/half of myocardium and usually due to hypoperfusion due to hypotension or shock
Factors that may influence the ultimate size of an infarct
- site of occlusion
- duration of ischemia
- collateral vessels supply outer layer so more likely to be subendocardial
- metabolic needs of myocardium
- reperfusion injury: after restoring blood flow due to mitochondrial dysfunction, myofibril hypercontracture with cytoskeletal damage and cell death due to Ca influx; damage to membrane proteins; leukocyte aggregation; platelet and complement activation
Know the following summary of the chronologic sequence of morphologic light microscopic changes in MIs:
a) contraction bands & myocyte necrosis
b) neutrophilic infiltrates
c) macrophages
d) granulation tissue
e) fibrosis (weeks later)
- 4-12hrs: wavy fibers (noncontractile ischemic fibers stretch with systole)
- 18-24hrs: coagulation necrosis, contraction bands at periphery of infarct, neutrophilic infiltrate
- 24-72hrs: max neutrophilic infiltrate
- 4-7days: macrophages with disintegration of necrotic myocytes (max softening)
- 10days: granulation tissue
- 4-8wks: fibrosis
Complication of acute MI and their clinico-pathological correlations
- 25% sudden cardiac death
- 80-90% complications if make to hospital
- arrhythmia
- LV failure and pulm edema
- cardiogenic shock
- pericarditis
- rupture of papillary muscle
- ventricular aneurysm
- rupture of wall leading to cardiac tamponade in 3wks
- mural thrombus/embolism
Main cardiac pathologic finding in hypertensive (systemic) heart disease
- concentric hypertrophy (sarcomeres in parallel to long axis of myocyte –> inc diameter) –> inc in wall thickness and O2 demand –> likely ischemic injury
- HTN can be caused by primary idiopathic HTN (most common) and also renal artery stenosis, endocrine problems, and vascular problems like coarctation of aorta
Definition of aneurysm and etiologies and main clinicopathologic features of aneurysms
- aneurysms are localized abnormal dilation of a vessel and occur due to weakening of the wall
- can be caused by atherosclerosis, HTN, vasculitis, developmental defect, infection, congenital disease
- occlusion of vessel –> ischemia/infarction
- thromboembolism
- rupture
Understand vessel dissection and know the predisposing causes of aortic dissection
- blood tears/dissect media of aorta and can go back into lumen, paricardial sac, or branches or even mediastinum
- sudden onset of severe pain radiating to the back
- unequal pulses, murmur, hypotension
- HTN can be a risk factor as well as CT disorders (marfan syndrome)
The clinicopathologic features of temporal arteritis, leukocytoclastic vasculitis, polyarteritis nodosa and Wegener’s granulomatosis
Temporal (giant cell) arteritis:
- most common
- segmental chronic granulomatous vasculitis of temporal artery
- elderly women
- headache, tenderness, visual problems
- corticosteroids help a lot
Leukocytoclastic vasculitis:
- arterioles, capillaries, venules affected
- usually due to drugs or infections
Polyarteritis nodosa:
- acute segmental necrotizing in small and medium arteries usually in kidneys, GI tract, and heart
- thrombus –> organ infarcts and aneurysms
- middle aged men
- immunosuppressants help
Kawasaki’s disease:
- acute necrotizing vaculitis in children that targets coronary arteries
Wegener’s granulomatosis:
- idiopathic necrotizing granulomatous vasculitis of small/medium arteries and veins especially upper and lower resp tracts and kidneys
Which vascular lesions are benign and malignant
Benign:
- granuloma pyogenicum (polypoid granulation tissue nodule on skin; reactive process; due to trauma or pregnancy)
- capillary and cavernous hemangioma (vascular neoplasm affecting skin)
Intermediate:
- Kaposi sarcoma (malignant tumor with skin, mucosal, or organ involvement)
- hemangioendothelioma
Malignant:
- angiosarcoma (malignant tumor involving skin, soft tissue, breast, or liver)
What are clinical manifestations secondary to insuff blood supply to heart?
1) angina pectoris:
- chest pain due to ischemia
2) acute MI:
- irreversible myocyte necrosis due to prolonged ischemia
3) chronic ischemic heart disease:
- progressive cardiac decompensation due to atherosclerosis with acute infarct or small ischemic events
- replace myocardium with fibrous tissue
What is the difference between stable and unstable plaques?
Stable:
- dense fibrous caps with minimal inflammation and small lipid cores
Unstable:
- prone to rupture
- thin fibrous cap
- large lipid core
- increased inflammation
- neovascularization
- hemorrhage
What determines the location of an infarct?
- where the occlusion occurs and right vs. left dominance
- usually infarct of left ventricle and septum
- some extend into right ventricle
- occlusion of LAD –> anterior, apical and septal LV infarct
- occlusion of RCA –> posterior LV and septum
- occlusion of LCA –> lateral left ventricle wall
Describe the morphology of MIs
0-30min: reversible ultrastructural and biochemical changes (mitochondria welling, sarcoplasmic edema, dec glycogen)
1-2hrs: irreversible changes (very swollen mitochondria, nuclear clumping, sarcolemma disruption –> release of intracellular proteins and disruption of ion gradients)
4-12hrs: wavy fibers (noncontractile ischemic fibers stretch with systole)
18-24hrs: coagulation necrosis, contraction bands at periphery of infarct, neutrophilic infiltrate
24-72hrs: max neutrophilic infiltrate
4-7days: macrophages with disintegration of necrotic myocytes (max softening)
10days: granulation tissue
4-8wks: fibrosis
What can cause cor pulmonale?
- primary lung disease due to chronic obstructive airways disease
- pulm vessel disease (PE)
- chest movement disorder
What are berry aneurysms?
- congenital defects in media of arteries at bifurcation of cerebral vessels (circle of willis)
- most frequent cause of spontaneous subarachnoid hemorrhage
- multiple at once
- onset presents as severe headache
Describe atherosclerotic aneurysms
- plaque compresses underlying media –> thinning of wall along with inflammation degrading ECM
- usually occur >50yo
- most common site is lower abdominal aorta below renal arteries
- half of patients are hypertensive
- many are asymptomatic and present with just a pulsating mass
What is vasculitis?
- inflammatory process involving vessels with inflammation and damage to vessel wall
- narrowing of lumen, fibrosis, thrombosis with ischemia/infarction, aneurysm formation
- immune complex deposition
Describe the general mechanisms of platelet function, coagulation, and fibrinolysis, with special emphasis on the sites and targets for pharmacotherapeutic interventions in disorders of hemostasis
Common targets:
- warfarin inhibits synthesis of vitamin K dependent factors 2, 7, 9, 10 as well as protein C and S (which inhibit factor 5 and 8)
- heparin combines with antithrombin III to inactivate 2a and 10a
- LMWHs combine with antithrombin III to inactivate 10a only
- dabigatran inactivates 2a
- rivaroxaban inactivates 10a
Review the process of primary hemostasis
1) damage to vessel exposes collagen of subendothelial layer
2) transient vasoconstriction
3) platelets adhere to damaged endothelium with vWF and get activated
4) platelets get activated and release ADP and TXA2 causing platelet aggregation with GP2b3a receptors
5) fibrin binds to GP2b3a receptors and holds platelets together
6) endo cells release PGI2 that is antiaggregatory and vasodilatory as well as plasmin to start fibrinolysis
Review the process of secondary hemostasis
- tissue damage exposes TF –> activates factor 7 –> activates factor 10
- 10a activates thrombin from prothrombin
- thrombin activates fibrin from fibrinogen
What are common lab test for blood coagulation?
aPTT
- intrinsic pathway
- monitors heparin therapy
PT
- extrinsic pathway
- monitors warfarin therapy
ECT (ecarin clotting time)
- monitor anticoag therapy with direct thrombin/2a inhibitors (dibgatran)
TT (thrombin time)
- prolonged if fibrinogen levels low
- monitors dabigatran toxicity
What are regulators of coagulation and fibrinolysis?
1) prostacyclin and NO cause vasodilation and inhibit aggregation
2) ATIII inhibits 2a, 10a (9a, 12a) and is accelerated with heparin
3) protein C/S inactivates factor 5a and 8a –> dec rate of prothrombin and factor 10 formation
4) fibrinolysis by activation of plasminogen to plasmin by tPA
Describe the mechanism of action and pharmacokinetics; list the uses, adverse reactions (plus treatment of overdosage if applicable), and drug-drug interactions; and disadvantages of heparin
Mechanism of action:
- acts in plasma to inhibit activated factors 2a, 10a (9a, 11a, 12a, 13a)
- accelerates ATIII
- LMWH binds 10a but not 2a; does not need to be monitored because doesn’t affect aPTT
Pharmacokinetics:
- given IV
- can give in pregnant women
- 1st order renally eliminated
- cont infusion
- heparin: rapid onset of action
- LMWH: 3-5hr onset
- monitor with aPTT
- eliminated renally
Uses:
- prevent hypercoag
- LMWH is preferred
- treats coronary occlusion in unstable angina/acute MI
- prevents VTE
Adverse reactions and treatment for overdose:
- hemorrhage
- thrombocytopenia
- osteoporosis
- use protamine for overdose (really + to neutralize really - heparin)
Drug drug interactions:
- inc bleeding with aspirin, ibuprofen, other antiplatelet agents
Describe the mechanism of action and pharmacokinetics; list the uses, adverse reactions (plus treatment of overdosage if applicable), and drug-drug interactions; and disadvantages of warfarin
Mechanism of action:
- acts in liver to prevent synthesis of factors
- blocks liver synth of vit k dep factors (2, 7, 9, 10)
- onset delayed due to delayed turnover of existing clotting factors
- protein C/S have shorter half lives so can actually cause coagulation early on
Pharmacokinetics:
- 100% oral absorption
- contraind in pregnancy
- genetic polymorphisms can affect therapy
- hepatic metabolism
Uses:
- afib: prevents thromboemoblus
- monitor with INR/PT
- bridge with heparin for first few days
Adverse reactions and treatment for overdose:
- hemorrhage
- GI
- contraind in pregnancy
- if INR>10 then stop warfarin and give vitamin k; slow infusion if bleeding
- prothrombin complex concentrate over fresh frozen plasma; or recomb factor 7a
Drug drug interactions:
- inc PT with amiodarone, metronidazole, fluconazole, fluoxetine, rosuvastatin, aspirin
- dec PT with barbiturates, carbamazepine, rifampin, vitamin k
Describe the mechanism of action and pharmacokinetics; list the uses, adverse reactions (plus treatment of overdosage if applicable), and drug-drug interactions; and disadvantages of dabigatran
Mechanism of action:
- acts in plasma to inhibit thrombin (2a)
- doesn’t require monitoring or dose adjustments
Pharmacokinetics:
- oral
- polar with bad bioavailability
- prodrug is well absorbed by GI and converted
- renally excreted
Uses:
- reduce risk of stroke and systemic embolism in patients with afib
- advantages over warfarin: lower stroke rate, no monitoring, no diet restrictions
- disav over warfarin: twice daily dosing, shorter acting, dose adjustments for renal impairment
Adverse reactions and treatment for overdose:
- GI complaints
Drug drug interactions:
- fewer drug or food interactions than warfarin
Describe the mechanism of action and pharmacokinetics; list the uses, adverse reactions (plus treatment of overdosage if applicable), and drug-drug interactions; and disadvantages of rivaroxaban
Mechanism of action:
- acts in plasma to inhibit factor 10a
- doesn’t need monitoring
- no antidote for rapid reversal of effect
Pharmacokinetics:
- oral
Uses:
- prevent DVT
- reduce risk of stroke and systemic embolism in patients with afib
- adv over warfarin: lower stroke rate, no INR monitoring, no diet rest once daily dosing,
- disad compared to warfarin: shorter acting, no antidote for reversal, apixaban required 2/day dosing, dose adjust for renal impairment
Adverse reactions and treatment for overdose:
- bleeding
- anticoag is difficult to reverse (FFP then PCC or r7a)
Describe the mechanism of action and pharmacokinetics; list the uses, adverse reactions (plus treatment of overdosage if applicable), and drug-drug interactions; and disadvantages of aspirin
Mechanism of action:
- inhibits COX1 synth of TXA2 in platelets
- TXA2 normally allows for GP2b/3a receptors, but dec so dec aggregation
Pharmacokinetics:
- once orally in low dose daily
- can be rapid onset
- hepatic elimination
Uses:
- acute MI (STEMI) plus an ADP antagonist
- unstable angina (UA/NSTEMI) maybe with an ADP antagonist
- percutaneous coronary intervention (PCI) plus ADP antagonist and maybe GP2b/3a inhibitor
- 2ndary prev of MI
Adverse reactions and treatment for overdose:
- bleeding risk with anticoag
- rare with low doses
- nausea, GI bleeding
Describe the mechanism of action and pharmacokinetics; list the uses, adverse reactions (plus treatment of overdosage if applicable), and drug-drug interactions; and disadvantages of clopidogrel
Mechanism of action:
- ADP receptor antagonist –> interferes with ADP induced platelet aggregation
Pharmacokinetics:
- once daily orally
Uses:
- acute MI (STEMI): aspirin + clopidogrel
- unstable angina/NSTEMI: aspiring and maybe clopidogrel
- PCI: aspirin + clopidogrel
Adverse reactions and treatment for overdose:
- upset GI, headache, dizziness, URI
- bleeding
Describe the mechanism of action and pharmacokinetics; list the uses, adverse reactions (plus treatment of overdosage if applicable), and drug-drug interactions; and disadvantages of dipyridamole
Mechanism of action
- blocks phosphodiesterase breakdown of cAMP –> inc cAMP –> inc PGI2 –> inc vasodilation and anti-aggregatory
Pharmacokinetics:
- orally 3-4x daily before meals
- hepatic elimination
Uses: secondary prevention of MI with aspirin
Adverse reactions and treatment for overdose:
- minimal
- some dizziness and GI distress