Cardiology Flashcards
What are the 3 pathological process in Virchow’s triad that contribute to clot formation?
venous stasis, vascular injury, hypercoagulability
What kind of factors activate the clotting cascade?
clotting factors
what kind of factors inhibit the clotting cascade?
anticoagulants
Unfractionated Heparin: mechanism, indications, adverse rxns, contraindications, pregnancy category
Mechanism: potentiates anti-thrombin III to block thrombin (IIa)(thus inhibiting fibrinogen), also blocks IXa, Xa, XIa, and XIIa, prevents coagulation, but DOES NOT affect an established thrombus
Indications: venous thromboembolism prevention and tx, unstable angina, MI, coronary bypass surgery, hemodialysis, angioplasty, IV line flushes
Adverse rxns: bleeding, Heparin induced thrombocytopenia (HIT–platelets
pregnancy category: C: does not cross placenta, caution with hemorrhage, osteoporosis, does not enter breast milk
UFH dosing, monitoring, reversal
dosing: Loading 80 units/Kg IV push, then continuous infusion of 18 units/Kg/hr (continuous because short half life) (lower in elderly) or subQ q8-12 hr if non acute
monitoring: aPTT (activated partial thromboplastin time) in 6 hr, platelets quod x 14 days
reversal: protamine(binds heparin) 1 mg to neutralize 90 units of UFH, max dose 50 mg, infused over 10 minutes (caution for hypotension and anaphylactoid rxns)
what are the pharmacokinetics of UFH?
Binds to endothelial cells, macrophages, and plasma proteins (low bioavailability), non linear clearance (saturable kinetics b/c large dose), half life increases with increasing doses (30-150 minutes, avg 90)
what is the reference range for aPTT and what should it be on UFH?
normal: 25-39 seconds, 45-75 seconds on UFH (1.5-2X control)
what are some of the advantages of Low molecular weight heparins as compared to UFH?
1/3 the size, higher subcutaneous bioavailability (92%), inhibit clotting factor Xa ONLY, very predictable dose response, longer half life, reduced need for lab monitoring
What’s an example of LMWH?
generic: enoxaparin; brand: lovenox
what are the indications for enoxaparin/lovenox?
DVT prophylaxis after hip or knee replacement surgery, or tx for VTE/TE
Is the dosing for prophylaxis (preventative measures) of blood clots higher or lower than dosing for treatment?
lower
what’s the dosing for enoxaparin/lovenox for DVT prophylaxis after hip or knee replacement surgery?
30 mg sc q 12 hr for 7-10 days until ambulatory
what is the dosing for enoxaparin/lovenox for VTE tx?
1 mg/kg sc q 12 h or 1.5 mg/kg sc Q24 hr
what disease would necessitate a lower dose of enoxaparin/lovenox?
severe renal impairment
what are the possible adverse rxns of LMWH?
bleeding, thrombocytopenia (lower incidence HIT than UFH, check on day 3 therapy), injection site hematoma, minor bleeding at site of injection, osteoporosis (less than UFH)
what/when do you monitor LMWH? what’s the therapeutic dose for VTE tx and VTE prophylaxis?
Baseline: PT, INR, APTT, CBC, serum, creatinine, platelets; steady state level 4 hrs after sub doseplatelets q3-5 days for 1st 2 weeks; anti factor Xa activity in pts with CrCl 14 days), no routine monitoring necessary
therapeutic dose VTE tx: 0.5-1 units/ml; VTE prophylaxis 0.2-0.4 units/ml
what’s the reversal for LMWH?
protamine 1 mg per 1 mg enoxaparin, although this cannot neutralize the anticoagulation effect of LMWH completely
What are some examples of other parenteral anticoagulants?
fondaparinux (Factor Xa inhibitor) and Argatroban (direct thrombin inhibitor)
what are fondaparinux’s mechanism, indications, and kinetics? is there a reversal? what are some drug intx?
Mechanism; inhibits factor Xa
indicated: for VTE prophylaxis for LE orthopedic procedures and tx of VTE, also indicated for HIT (unapproved)
kinetics: longer 1/2 life, so only dosed once daily
no reversal
few drug intros b/c not metabolized in liver
what is argatroban’s mechanism, indications, monitoring, adverse affects, and reversal agents?
directly inhibits circulating and bound thrombin (aka synthetic leech saliva), doesn’t bind plasma proteins=predictable dose response
indications: HIT, patient undergoing PTCA, HIT with PTCA, VTE prophylaxis in hip surgery
monitor: aPTT
adverse affects; high incidence of bleeding
no reversal agents
what is warfarin’s MOA, onset of effect, indications, and adverse reactions, and reversal?
MOA: vitamin K antagonist: interferes with hepatic synthesis of vitamin K dependent clotting factors, resulting in depletion of factors II, VII, IX, X, thus the half life is dependent on the half life of these clotting factors, no effect on est. thrombus or already formed clotting factors
onset of effect: 36-72 hours, full effect in 5-7 days
indications: VTE tx/prophylaxis, prosthetic heart valves, atrial fibrillation, TIA/stroke, acute MI, hyper coagulable states, peripheral arterial occlusive disease
adverse reactions: bleeding (minor in 2-10%), skin necrosis (rare, early, 3-8 days after starting–d/c drug, give Vit K and heparin), purple toe syndrome (later onset 3-10 wks, reversible but need to d/c drug)
reversal is vitamin K
What is warfarin’s pregnancy category and contraindications?
Pregnancy category X, CI: patients with add’l risk of hemorrhage, anyone at risk of noncompliance, surgery/dental work (before surgery go off it and after restart with LMWH which works faster), alcoholism (will cause liver damage), spinal anesthesia or spinal injections (don’t want blood in spinal cord)
what are the pharmacokinetics and metabolism of warfarin?
absorbed well in GI tract (97-99%), food in stomach may increase rate but not extent of absorption. >97% bound to plasma proteins like albumin, crosses placenta and through breast milk
metabolism: plasma half life is 1-2 days, longer in elderly with CHF (less blood flow, slower metabolism)
what is the dosing for warfarin?
4-5 mg qd, overlap with heparin for 4-5 days (shorter half-life for heparin, works faster than warfarin); NOTE: very wide range of doses depending on pt, age
What is the INR?
International normalized ratio, standardizes therapies since PT reagents vary in sensitivity
INR=PT (pt)/PT (control)
reference range is about 1
What are the INR goal ranges for VTE tx and prophylaxis, atrial fibrillation, acute MI? for which conditions is the goal range larger?
2.0-3.0; larger (2.5-3.5) for some mechanical valves like caged ball/disk, mitral tilting disk
how long do most people take warfarin?
3-6 months for tx of VTE or MI or a bioprosthetic heart valve with previous embolism; lifetime for prophylaxis or mechanical heart valves or atrial fibrillation
what’s a good rule of thumb for warfarin drug intx?
assumes interacts with warfarin until proven otherwise; have patients check with health care provider before starting any new meds
what are the 3 ways other drugs can interact with warfarin?
other drugs can dangerously increase the INR with warfarin; can decrease the anticoagulation effect/INR (these drugs induce CYP450); or they can increase the bleeding risk without changing the iNR (makes platelets more slippery)
what are 4 important drugs to remember that warfarin intx with?
aspirin (increase bleeding risk), vitamin K (antidote/decreases therapeutic effect), sulfamethoxazole aka bactrim/septrim for acne increases the anticoagulation effect
what kinds of foods can interfere with how warfarin works?
vitamin K prevents warfarin MOA: in green vegetables; tell patients its good to eat them just eat a consistent amount so we can keep their dose right; acute EtOH can increase the INR (gets fatty deposts in liver for a few days that prevents liver from working) and chronic EtOH can decrease the INR, cirrhosis can increase the INR
what are examples of “other’ oral anticoagulants and what are their MOAs?
Dabigatran (direct thrombin inhibitor), rivaroxaban (oral factor Xa inhibitor), Apixaban (oral factor Xa inhibitor), Edoxaban (Xa inhibitor)
Which “other” oral anticoagulant is a little safer in pregnancy? (the others are all Category C)
apixaban
what are the indications for the “other” oral anticoagulants?
VTE prophylaxis/tx, thromboembolism tx in Afib, DVT/PE tx/prevention with hip/knee replacement (for dabigatran and rivaroxiban)
which oral anticoagulant is best for people with CrCl
edoxaban
Which “other” oral anticoagulant is a prodrug that doesn’t require any monitoring, has no antidote, and that is a good substitute for warfarin in those that can’t tolerate it but whose capsules have some quirky sensitivities?
dabigatran
which drug is more effective than enoxaparin after total knee replacement, but its more expensive, with no specific antidote?
rivaroxaban
which drug is a good substitute for those who can’t tolerate warfarin or dabigatarn, but is not recommended in pots with prosthetic heart valves?
apixaban
what are the pros of other oral anticoagulants?
at least as effective as warfarin for stroke prophylaxis, have a faster onset, fewer drug intx, and cause less intracranial bleeding
what are the cons of other oral anticoagulants?
no specific antidote, require strict adherence–even stopping for a few days can put them back at risk for clots, more expensive, need dose adjustments with renal insufficiency, and should not be used in people with mechanical heart valves
what is the recommended tx for VTE treatment?
start on parenteral anticoagulat (like UFW, LMWH, or fondaparinux) for 5-7 days; after first dose of parenteral give oral anticoagulant (like warfarin) right after first dose, must have therapeutic INR for 2 days before stopping
in which case is a thrombolytic indicated?
for those with acute massive embolism who are hemodynamically unstable, plus lower risk of bleeding, and without risk of right ventricular injury
what gene may influence how warfarin is metabolized?
gene for CYP2C9, which normally metabolizes warfarin
which indications require a long term/lifetime duration of therapy of an anticoagulant?
second episode of VTE, or a first, unprovoked proximal DVT or unprovoked PE
what is the recommended duration of therapy for the first episode of VTE secondary to a transient risk factor?
3 months
what is the most common cause of death in the US and the leading cause of premature, permanent disability?
Coronary Heart Disease (CHD)
Lowering ________ reduces atherosclerotic progression and mortality from CHD
Cholesterol
T or F: Most patients at risk for CHD receive optimal treatment
False
What is something all HTN and dyslipidemia puts should be “prescribed”?
life style modifications: healthy food choices, weight reduction, increased physical activity, avoid tobacco
What are statins MOA, adverse effects, CIs, and drug intx, and monitoring?
MOA: 1) inhibit HGM co-reductase (rate limiting enzyme in endogenous cholesterol biosynthesis), 2) increase catabolism (break down) of LDL to clear it from plasma 3) anti-inflammatory (decrease C reactive protein)
adverse effects: hepatic toxicity: elevated transaminases in 1-2% of cases at high doses, myopathy in 1 in 10 pts with higher doses, neuropathy (very rare- 1/14000), small increased risk of DM, non serious and reversible cognitive side effects
CIs: pregnancy, active or chronic liver disease, concomitant use with CSA (cyclosporin–antirejection drug), gemfibrozil, and niacin
Drug intx: reports of myopahty with drugs above, + erythromycin and some antifungals, may potentiate oral anticoagulants, and increased effect of levothyroxine
monitoring: lipids, ALT baseline (liver), ALT as clinically indicated thereafter, CK prn if muscle pain
what is the relationship between LDL and CHD?
Log linear: for every 30 mg/dL increase in LDL there is a 30% increased risk of CHD (GOOD FOR PATIENT EDUCATION)
What is the relationship between MI and C reactive protein (CRP)
Increased CRP increases risk of MI because the plaques that burst and cause a clot have extra inflammation from CRP
What kind of dose/response relationship do statins have?
non linear–“get more bang for your buck at lower doses” Each doubling of dose only results in 6% reduction of LDL
which drug for dysplipidemia shows the best evidence for decreasing: LDL, mortality, cardiac risk, stroke incidence, and MIs?
statins
how are statins usually dosed?
lovastatin with evening meal, atorvastatin at any time, the rest at bedtime (HS)
why can grapefruit juice be a bad thing with statins?
It can inhibit the CYP450 enzyme that statins are metabolized by
What decrease in LDL and TG can diet alone provide?
10-15% for LDL, 10-20% for TG, it also decreases weight and BP which helps!
Which drug is the best at decreasing LDL? Which is second best?
Best is PCSK9, although this drug isn’t approved by FDA yet and is very expensive, the next best are statins
How do bile acid resins work? What’s an example? what are the adverse effects, monitoring CIs,?
they 1) stimulate LDL receptors to increase LDL catabolism 2) They bind bile acids and excrete them in stool, thus liver is forced to use cholesterol to make more which decreases LDL 3) may increase VLDL -> TG
example is cholestyramine (“chole-“ means bile or relating to bile ducts)
adverse effects are GI symptoms (can start at low dose and titrate to get GI to adjust, also increase fluid and fiber) -> this can cause noncompliance if they make them feel crummy–have them take 1 hr before or 2 hrs after meal to avoid intx
monitoring: lipids 6-12 wks after stable dose then q yr
CIs: already highly increased TGs (may increase TGS more and cause pancreatitis), familial dysbetalipoproteinemia (basically inheriting high TGs), h/o severe constipation
What are fibric acids MOA, example of one, effect on lipids, AE, monitoring, CIs
MOA: increase VLDL clearance and decrease VLDL synthesis (thus best at decreasing TGs)
example: fenofibrate
Mildy decrease LDL and increase HDL, tied for best at decreasing TGs
AE: GI, can increase bile lithogenicity (stones), can interfere with statins
monitoring: lipids 6-12 wks after dose change, q yr after; ALT baseline, 6-12 wks x2, then q yr; CK PRN myositis
CIs: h/o gallbladder disease or liver or kidney dysfunction (stones)
What is a common side effect of nicotinic acid? what is it best at lowering/increasing? how does it work? how do you monitor it?
flushing (tolerance develops over time, can be mitigated with ibuprofen during 1st 2 weeks and extended release niacin causes less flushing and is less hepatotoxic); best at increasing HDL, and tied for best at lowering TG
MOA: decreases LDL and VLDL synthesis
monitoring: lipids x2 months uric acid, glucose then q yr; baseline ALT, 6-12 wks, then q yr, CK prn myositis
How does ezetimibe work? what are some AE? what is it often combined with?
blocks cholesterol receptor and thus absorption on brush border of enterocytes, causing body to insert more LDL receptors which decreases LDL
AE: fatigue, abdominal pain, diarrhea, arthralgia, back pain
often combined with statins for pts with liver disease
How does PCSK9 work?
Works by preventing PCSK9 from degrading liver LDL receptors
what are some supplements for lowering cholesterol? how do they work?
plant stanol esters: competitively inhibit incorporation of cholesterol into micelles, decreasing total cholesterol and LDL in a dose dependent way, max LDL reduction 15%
fish oils: can reduce TGs by 20-50% with side effects of diarrhea and excess bleeding
others: oat bran, blond psyllium
what is a very important thing to educate patients on regarding the duration of their tx for HTN?
For most patents it is a life long tx
1 out of every _____ adults has HTN
3
In what ethnicity is HTN most prevalent?
african americans
what are the known causes of HTN?
known causes: sleep apnea, drug induced causes, CKD, primary aldosteronism, renovascular disease, chronic steroid therapy and cushing’s syndrome, pheochromocytoma, coarctation of the aorta, thyroid or parathyroid disease; meds that may increase it: NSAIDS, cox2, cocaine/amphetamines, sympathomimetics (decongestants, anorexiants), oral contraceptives, certain dietary supplements (ma haung, bitter oragne, guarana), corticosteroids, cyclosporine (anti rejection), erythopoietin, licorice
Diuretics: thiazides MOA, AE, special indications, example drug
MOA:at distal tubule: increases Na excretion and h20, which decreases plasma volume and CO, decreases extracellular fluid volume, some decrease in peripheral resistance over time
AE: hypokalemia, hypomagnesemia, hyperuricemia, hyperglycemia, slight increase of TGs but not significant (indapamide less of an effect)
special indications:effective in renal insufficiency if SCR >2.5
example: chlorthalidone
Chlorthalidone (thiazide) dosing
12.5-25 mg daily
diuretics: potassium sparing MOA, AE, special indications, example drug
weak diuretic effects at collecting duct, distal tubule. Conserves potassium, also aldosterone antagonists
AE: may cause hyperkalemia when given with K supplements or ACE inhibitors or in pts with renal insufficiency, gynecomastia
special indications: often used with thiazides to offset K loss for HTN tx
example: spironolactone
spironolactone (potassium sparing diuretic) dosing
25-200 mg/day in 1-2 divided doses
loop diuretics MOA, AE, special indications, example drug
MOA:more potent diuretic effect at loop of henle to increase Na excretion
AE:more potent effects than thiazides on K, Mg, overdiruesis, and metabolic alkalosis
special indications: used over thiazides esp for those with heart failure or renal sufficiency who need to get rid of more fluid
example: furosemide
furosemide (loop diuretic) dosing
10-160 mg daily in 1-2 divided doses
ACEi MOA, AE, CI, example
MOA: 1) block angiotensin converting enzyme to block angiotensin II (vasoconstrictor) and 2) decrease aldosterone to decrease sodium retention 3) increase bradykinin for vasodilation, possibly reduce hypertrophy of CV tissue (vessels, heart)
AE: may cause hyperkalemiam, monitor esp if on K supplement of K sparing diuretic, cough, hypotension, rash, angioedema, acute renal failure in pts with bilateral renal artery stenosis or significant dehydration
CI: 2 or 3 trimester of pregnancy
example: lisinopril
lisinopril dosing
5-40 mg daily, consider decreasing or d/c diuretic to avoid excessive hypotension
Angiotensin II receptor blockers (ARBS) MOA, AE, special indications, example
MOA: block angiotensin II receptor to cause vasodilation and decrease aldosterone (decreases sodium retention) (but no effect on bradykinin)
AE: may cause hyperkalemia, monitor esp if on K supplement of K sparing diuretic, , hypotension, angioedema, acute renal failure in pts with bilateral renal artery stenosis or significant dehydration
indication: for pts who cannot tolerate ACEi
example: losartan
losartan dosing
25-100 mg qday
direct renin inhibitors: MOA, AE, special indications, example
MOA: directly inhibit renin which leads to vasodilation and decreased sodium retention
AE: diarrhea (esp with higher dose), cough, angioedema (but less than ACEI)
CI: pregnancy
example: aliskiren
calcium channel blockers MOA, AE, CI, example, indications
MOA: block intracellular influx of calcium thereby preventing vascular smooth muscle contraction (leads to vasodilation/relaxation),
AE: possible severe HA, dizziness, peripheral (ankle) edema, eczema in elderly (3-6 mo after)
CI: pts with HF (heart needs the calcium for contractile force) if EF 2+pitting edema or with symptomatic hypotension
example: amlodipine
indications for dihyrdopyridines: contractility - , peripheral vasodilation +++, CSA if HR goal,
dihydropyridine class: amlodipine dosing
2.5-10 mg qday
non dihydropyridine class: diltiazem and verapamil dosing
diltiazem 30-90 mg tid; verapamil 40-240 mg bid
which CCB class is the best at vasodilation?
dihydropyridine
which CCB class is the best at contractility?
non dihydropyridine–drug is verapamil; diltiazem is second best
what are some adverse effects of beta blockers/
b2 blockers can aggravate asthma and other lung diseases, CI in pts with bradycardia, heart block, sinus node disease (can slow HR with b1 blockers), use caution in uncontrolled heart failure, can cause fatigue, insomnia, depression, nightmares, bradycardia, ED (decreased perfusion to periphery), aggravate peripheral vascular disease, mask signs of hypoglycemia, mildly lower HDL and mildly increase TG, do not stop abruptly in pts with ischemic heart disease: taper