Exam 3: CAD and Heart Failure Pharmacotherapy Flashcards
Coronary blood flow at rest:
70 ml/min/100g
% O2 extraction by myocardial tissue beds:
70% (very high!)
Heart gets ____% of CO:
5%
Coronary blood flow increases ____x during intense exercise:
2-4x
Cardiac demand increases _____x during intense exercise:
4-7x
Systolic contraction impedes coronary filling because:
Intramural pressure increases, redistributes blood from subendocardial to subepicardial layers, compresses vessels
Perfusion pressure to LV =
DBP - LVEDP
Tachycardia during anesthesia greatly increases the chance of:
Myocardial ischemia
Factors (4) that ↑ myocardial O2 demand:
Tachycardia*
High afterload (↑ SVR)
High preload
↑ contractility
Factors (6) that ↑ myocardial O2 supply:
Hgb concentration O2 saturation Bradycardia (w/in reason) ↑ DBP Low-normal preload ↓ contractility
Goal HR range and indicated drugs in pts with CAD:
Slow
Indicated: β-blockers, CCBs
Drugs (4) with negative effect on HR in pts with CAD:
Isoproterenol
Dobutamine
Ketamine
Pancuronium
Sympathomimetic/vagolytic
Goal preload and indicated drugs in pts with CAD:
Low-normal
Indicated: NTG, diuretics
Therapy with negative effect on preload in pts with CAD:
Volume loading
Goal afterload and indicated drugs in pts with CAD:
High-normal
Indicated: Phenylephrine
Drugs (2) with negative effect on afterload in pts with CAD:
Nitroprusside
High-dose volatile agents
Goal contractility and indicated drugs in pts with CAD:
Normal-low
Indicated: β-blockers, CCBs, high-dose volatile agents
Drugs (2) with negative effect on contractility in pts with CAD:
Epinephrine
Dopamine
Summary of stable angina treatment (mnemonic):
A: ASA/anti-anginals B: BP control C: cholesterol, cigarettes D: diet, diabetes E: education, exercise
MoA of organic nitrates:
Release NO after metabolism which ↑ NO concentration in smooth muscle cells
Relaxes coronary arteries to increase supply, decrease demand (↓ preload?)
Examples of organic nitrates:
NTG Isosorbide dinitrate (Isordil) Isosorbide mononitrate (Imdur)
Nitrates are not good long-term antihypertensives d/t:
Baroreceptor reflex ↑ HR
Describe the NO signal pathway on the endothelial cell side:
Endothelial cell: bradykinin activates GPCR, which ↑ Ca2+ and triggers calmodulin, which activates eNOS to turn arginine into NO, which diffuses out
Describe the NO signal pathway on the vascular smooth muscle cell side:
NO diffuses in and activates guanylyl cyclase to ↑ cGMP, which leads to decreased Ca2+ and vasodilation
Enzyme that converts (active) cGMP to (inactive) GMP:
Phosphodiesterase inhibitors
Nitrate effects on O2 consumption:
Reduces it via ↓ preload (venodilation) and ↓ afterload (arterial dilation)
Stronger effect of NTG: venodilation or arterial dilation?
Venodilation
NTG provides preferential dilation of:
Collateral vessels serving ischemic areas
Metabolism of nitroglycerin:
90% degraded by liver to inactive metabolites; sublingual/transdermal bypass first pass effect
E1/2t of NTG:
1.5 minutes
Adverse effects of NTG:
Headaches
Postural hypotension/syncope
Methemoglobinemia
Tolerance issues with NTG:
Limits the efficacy, regardless of the route
Must have nitrate-free intervals (usually at night, when O2 demand is lower)
Advantages of oral isosorbide mononitrate:
High bioavailability
Long t1/2
High levels during day, low levels at night
Drug interactions with nitrates:
Phophodisterase inhibitors (sildenafil, tadalafil, vardenafil) - additive effect w/ nitrates
Supply/demand benefit of β-antagonists in CAD:
↓ demand via ↓ CO from ↓ HR
↑ supply via longer diastolic filling time
Specific β-antagonists to use in CAD:
β1-selective agents: metoprolol, atenolol
Don’t want to ↓ flow to peripheral vessels
Benefit of β-antagonists post-MI:
↓ post-MI remodeling
S/E of β-antagonists:
Depression Insomnia Masking hypoglycemia Exercise intolerance Bronchospasm
Discontinuation of β-antagonists:
Do not stop suddenly due to receptor upregulation
MoA of CCBs:
Bind the α1 subunit of the L-type calcium channel in mode “0”, the state where channel will not respond to depolarization
Effect of CCBs at the SA node:
↓ HR (negative chronotropic effect)
Effect of CCBs at the AV node:
↓ conductivity (negative dromotropic effect)
Effect of CCBs at the cardiac muscle:
↓ contractility (negative inotropic effect)
Effect of CCBs at the coronary vasculature:
Vasodilation
Adverse effects of CCBs:
AV block Cardiac failure Headache Constipation Hypotension
All “too much of a good thing”
Examples of dihydropyridine CCBs:
Amlodipine
Nifedipine
Nicardipine
Dihydropyridine CCBs more selective for:
Ca2+ channels in the vasculature (esp. arterial)
Adverse effect specific to dihydropyridine CCBs:
May cause reflex tachycardia
Examples of non-dihydropyridine CCBs:
Verapamil
Diltiazem
Non-dihydropyridine CCBs more selective for:
Ca2+ channels in the heart muscle
Adverse effect specific to non-dihydropyridine CCBs:
Heart block
Avoid non-dihydropryridines in combination with:
β-blockers
Role of ASA in CAD:
Antiplatelet activity prevents thrombus formation
Tx of unstable angina/N-STEMI:
Anti-anginal drugs
Heparin/ASA
GPIIb/IIIa antagonists
Clopidogrel
Tx of STEMI:
Surgery
Thrombolytics
Indication for clopidogrel:
ACS pts with ASA allergy
Indications for GPIIb/IIIa inhibitors:
Reduce MI risk in pts w/ unstable angina
Reduce recurrent MI/revascularization in pts with NSTEMI
Tx for acute stable angina:
Nitrates
β-blockers
CCBs
Tx for acute unstable angina:
Nitrates β-blockers CCBs ASA/clopidogrel Heparin/thrombolytics GPIIb/IIIa inhibitors
Tx for variant angina:
Nitrates
CCBs
Effects of aldosterone on the heart:
Insult to myocardium
Causes remodelling
Promotes atherosclerosis
Systolic dysfunction is EF <
EF < 40%
Causes of systolic dysfunction:
CAD HTN Valvular disease ETOH Thyroid disease Cardiotoxic drugs
Causes of diastolic dysfuction:
Cardiomyopathies
Incomplete relaxation due to ischemia
Major manifestations of CHF:
Dyspnea
Fatigue
Fluid retention
Three physiologic goals of CHF tx:
↓ preload
↓ afterload
↑ inotropy
Drugs to reduce preload in CHF:
Diuretics
Aldosterone antagonists
Venodilators (NTG)
Drugs to reduce afterload in CHF:
ACEIs
β-blockers
Vasodilators
Drugs to increase inotropy in CHF:
Cardiac glycosides
Sympathomimetic amines
Phosphodiesterase inhibitors
Goal HR range in CHF and drugs indicated for this:
Normal-high
Indicated: dopamine, dobutamine
Drugs with negative effect on HR in CHF:
High-dose β-blockers
Goal preload in CHF and indicated therapy:
Normal
Indicated: IV fluids if needed
Drugs with negative effect on preload in CHF:
NTG
Thiopental
Goal afterload in CHF and indicated therapy:
Low
Indicated: ACEIs, nitroprusside, amrinone
Drugs with negative effect on afterload in CHF:
Phenylephrine
Goal contractility in CHF and indicated therapy:
Increased
Indicated: dopamine, dobutamine, epinephrine, amrinone
Drugs with negative effect on contractility in CHF:
High dose inhaled agents
High dose β-blockers
Important consideration before giving diuretics for CHF:
Preload status
Mortality benefit for thiazide/loop diuretics:
None - just QOL
Examples of loop diuretics:
Furosemide
Bumetanide
Torsemide
MoA of loop diuretics:
Inhibit Na+/K+/2Cl- cotransporter in Loop of Henle
↑ excretion of Na+, K+, H2O
Diuretics which work on the distal tubule:
Thiazides
Metolazone
Spironolactone/eplerenone
Distal tubule diuretics ↑ Na+ excretion by:
5-10%
Loop diuretics ↑ Na+ excretion by:
20-25%
MoA of spironolactone:
↓ K+/Na+ exchange in distal tubule (sheds Na+, spares K+)
Inhibits both androgen and mineralocorticoid receptors
S/E of spironolactone:
Gynecomastia
Impotence
Hair growth (women)
Spironolactone vs. eplerenone:
Eplerenone more selective with less S/E
Role of NTG in CHF:
Use with caution - these pts need preload!
Reduces preload and myocardial O2 demand
Alleviates ischemia to improve diastolic relaxation
Role of ACEIs in CHF:
Reverse RAAS-induced vasoconstriction, volume overload
Reduction of afterload also increases SV and GFR and increases diuresis
Drugs with proven mortality benefits in CHF:
Aldosterone antagonists ACEIs ARBs β-blockers Hydralazine + isosorbide dinitrate together in African-American pts
Role of ARBs in CHF:
Reduce RAAS-induced vasoconstriction/volume overload
Lack of bradykinin-related vasodilation means less preload reduction
Role of β-blockers in CHF:
Inhibition of renin release
Blunting of catecholamines
Preventing of ACS
NOT for use in acute, decompensated HF!
Role of hydralazine + isosorbide dinirate in CHF:
Vasodilators (hydralazine arterial, ID venous) - used when pts cannot tolerate ACEIs
MoA of digoxin:
Na-K-ATPase inhibitor
↓ SNS outflow, ↑ PSNS outflow
Effect on HR from digoxin:
↓ conduction velocity and ↑ AV refractory period leads to ↓ HR
Effect on contractility from digoxin:
Increased intracellular Ca2+; stronger contractions
Effect on renal aborption of Na+ from digoxin:
↓ renal absorption of Na+
Therapeutic levels of digoxin:
0.5 - 1.2 ng/ml
Onset and half-life of digoxin:
Onset: 30-60 min
t1/2: 36 hrs
Elimination of digoxin:
90% renally excreted
S/E of digoxin:
Hypokalemia
AV block
Ventricular ectopy
Tx for overdose of digoxin:
Digoxin immune fab
Drug interactions with digoxin:
Risk of AV block w/ β-blockers
↓ contractility from β-blockers, CCBs
Abx ↑ absorption
Verapamil, quinidine, amiodarone ↑ digoxin levels
MoA of phosphodiesterase inhibitors:
Inhibit degradation of cAMP/cGMP in myocytes, vascular smooth muscle
Increases intracellular Ca2+
↑ contractility
↑ art/ven dilation
↑ disastolic relaxation
Phosphodiesterase inhibitors a good choice for overdose of:
β-blockers
Onset, DOA and half-time for amrinone:
Onset: 5 minutes
DOA: 2 hrs
E1/2t: 6 hrs
Dosing of amrinone:
0.5 - 1.5 mg/kg IV
Infusion: 2-10 mcg/kg/min
Max dose 24 hrs: 10mg/kg
S/E of amrinone:
Hypotension
Thrombocytopenia
Arrythmias
Elimination of amrinone:
Renal excretion
Amrinone vs. milrinone:
Milrinone has less tachycardia and thrombocytopenia
Dosing of milrinone:
50mcg/kg IV
Infusion: 0.5 mcg/kg/min
Half-time of milrinone:
2.7 hrs
Elimination of milrinone:
80% excreted unchanged via renal
Applications of milrinone:
Acute managment, not long-term; long-term use increases M&M
Good for pulm HTN