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Myocardial Ischemia-
- *Usually from Atherosclerosis
- PRIMARY-
- 1. results from myocardial demand exceeding oxygen supply.
- 2. Reversible ischemia
- 3. Narrowed blood vessels
- MI-
- 1. Irreversible ischemia
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Myocardial demand is determined by:
Amount of evergy required to support the heart.
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Factors that influence work of the heart include:
- 1. HR
- 2. BP
- 3. Ventricular volume
- 4. Cardiac contractility
- 5. Myocardial wall tension (which is the result of myocardial wall thickness).
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CO=
Stroke volume (HR X volume per stroke) X TPR
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The hearts contractility:
- Calcim stimulates shortening of myocardial fibers which increases contractility, velocity of fiber shortening and peak systolic muscle tension increases.
- (Calcium influx causes systolic muscle tension to increase).
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Preload:
Is the measure of ventricular filling pressure or the volume of blood in the left ventricle at rest (prior to it filling up)
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Afterload:
- -Is the pressure that the heart must pump against- the higher the BP the harder the heart has to work.
- -Resistance to ventricular ejection.
- -Increased BP results in INCREASED afterload.
- -The thicker the walls the harder it has to work.
- -Regulated by ejection impedance, wall tensions and regional wall geometry.
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Preload/Afterload:
- 1. Ventricular diastolic pressure-(Preload)
- Is decreased when veins are dilated and venous pressure and cardicac filling pressure decreases.
- 2. Ventricular systolic pressure- (Afterload)
- Dilation of arteries decreases arterial and aortic pressure. decreases.
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S/S of Angina-
- 1. CP
- 2. SOB
- 3. Fatigue
- 4. DOE- "angina equivalent"- experience instead of CP.
- 5. Occurs with exertion, releived with rest.
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Hallmark symptom of Angina-
Pain with exertion and releived at rest.
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Risk factors-
- Modifiable-
- 1. Smoking
- 2. HTN
- 3. Dylipidemia
- 4. Obesity
- 5. Physical inactivity
- Nonmodifiable
- 1. Age
- 2. Family history
- 3. Gender
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Types of Angina-
- 1. Stable- precipitated by exertion, releived by rest.
- 2. Unstable angina- minimal exertion produces s/s. (CAN LEAD TO MI)
- 3. Nocturnal- at HS
- 4. Angina decubitus
- 5. Variant angina- arteris vasospasm
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Angina treatment-
- 1. History
- 2. Physical examination
- 3. Tests
- 4. Treatment goals
- *releiving anginal s/s
- *Prevent additional anginal episodes
- *Decrease r/f MI
- *Improve functional capacity
- *Prolong survival
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Prognosis determined by:
The number and location of coronary artery stnosis, the severity of ischemia, and the presence of other CAD r/f's.
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Angina treatment:
- 1. Nonpharmacological treatment
- *dietary changes
- *exercise
- *modify r/f's
- 2. Pharmacologic treatement-
- *increase cardiac oxygen supply to the heart (not really an option with drugs)
- *decrease oxygen demand on the heart by decreasing HR, decreasing contractility, and decreasing afterload or preload with medications.
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Agents for treatment-
- 1. Organic nitrates
- 2. BB's
- 3. CCB's
- 4. ACE inhibitors
- 5. Antiplatelet drugs- ASA DAILY!
- 6. Antilipid agents
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NITRATES-
- -act on smooth muscle!
- -prevent anginal episodes
- Action-
- -vasodilation
- -dilate the vasculature in peripheral arteries and veins which decreases oxygen demand on the heart.
- -decrease blood return to heart (preload)
- -decrease afterload
- -rapidly absorbed
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NITRATES- SHORT ACTING PRODUCTS-
- 1. Nitro SL
- 2. Nitro spray
- 3. Ointment, patch, po, sl, IV
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NITRATES- LONG ACTING-
- 1. Isosorbide
- 2. Transdermal Nitroglycerin patches
- *prophylaxis
- *maintain vasodilation and continuosly decrease workload of the heart
- *increases myocardial perfusion
- *veous pooling of blood, decrease in benous blood return to the heart, decrease in ventricual volume, pressure and wall tension, decrease cardiac work and oxygen demand and releive angina
- *results in increased transmyocardial gradient and increases myocardial perfusion
- *peripheral vasodilation also decreases cardiac afterload
- *decreases preload on the heart
- *ALL PTS WITH ANGINA SHOULD HAVE SHORT ACTING AND A LONG ACTING NITRATE!
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Nitrate tolerance-
- -loss of ability of smooth muscles to respond to nitrates both inperipheral and coronary arteries
- -occurs as early as 7-10 days after administration
- -SL, patches
- -Nitrate-free interval- at hs due to less activity
- -S/E's h/a, flushing, dizziness, weakness,orthostasis, reflex tachycardia
- -Precautions with nitrates- Phosphodiestrase- 5 inhibitors, Sildenfil (VIAGRA), Levitra, Cialis- causes severe HYPOTENSION.
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BETA BLOCKERS-
- -Decrease HR
- -Cardio-protectors
- -recommended as INITIAL therapy by all guidelines for all pts, with or without previous MI (unless contraindicated).
- -decreased myocardial demand.
- -main role is preventing recurrence of MI's in pts with CAD- decrease risk for reinfaction and improve survival in pts who have had an MI.
- -especially useful in those with exertional angina and resting tachycardia.
- -decreases workload of the heart
- -decrease myocardial oxygen demand by antagonism of adrenergic receptors
- -decreases myocardial contractility, decreased HR, decreases conduction velocity.
- -Nonselective BB decreases systemic vascular resistance and BP (afterload)
- -ALL BB decrease myocardial demand
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BETA BLOCKERS-
1. Atenolol-
- -most cost-effective
- -once-daily dosing
- -low adverse reactions profile
- -Beta 1 selectivity ****
- -preferred in DM d/t prolong recovery from hypoglycemia with nonselective BB's and blunting of hypoglycemic symptoms*****.
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BETA BLOCKS:
- 1. Cardioprective-
- decrease incidence of ventricular arrhytmias that cause sudden death s/p MI
- 2. Contraindications-
- If hx of bradycardia, decompensating CHG, DM, asthma(if severe)
- 3. Caution with drugs that depress AV conduction - DIGOXIN, verapamil, cardizem- increase risk of bradycardia and heart block.
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ACE's-
Diuretics-
Glycosides (Digoxin)-
Women are at a higher risk when?
- 1. ACE's- decrease cardiac workload.
- 2. Diuretics- control excess fluid.
- 3. Glycosides (Digoxin)- improve myocardial contractility (inhibit Na, K, ATpase)
- 4. After menopause
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CCB's-
- Two classes-
- 1. Dihydropyridines (amlodipine, nicardipine,and nifedipine)
- 2. Nondihydropyridines (beprodil, dilitazem, and verapamil)
- *BOTH prevent calcium reflux into cells, produces smooth muscle relaxation of systemic and coronary arteries and suppresses cardiac activity....prevents CP
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CCB action in Angina-
- -depress cardiac contractility by decreased conduction through SA and V node which decreases MOD. (Dihydropyridines do not have this action)
- -decrease HR, conduction, and mediates antianginal effect
- -relieve coronary constriction with vasospastic angina
- -decrease afterload
- -vasodilation
- -increase MOS, decrease MOD
- -S/E's- constipation, decrease BP, h/a, increase CHF, can worsen GERD
- -Indications- Angina, HTN, tachyarrhythmias, migraine, Raynauds, esophageal spasm.
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ACE's-
- -recommended for pts with EF less than 40
- -DO NOT USED IN PREGNANCY
- -for symptomatic pts with chronic stable angina to prevent MI (reinfarction) or death, and to reduce s/s
- -Increase MOS and decrease MOD
- -prevent formation of angiotensin 2 (vasoconstrictor)
- -decrease PVR and decrease MOD d/t decreased afterload
- -decreases thickening of coronary artery walls which decreases MOS
- -decreases secretion of aldosterone, decreases the retention of sodium and water which decreases extracellular fluid volume and preload
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ANTIPLATELET THERAPY-
- -inhibits synthesis of thromboxane A2 in production of platelets which decreases platelet aggregation and vasoconstriction
- -indicated with pt with acute/chronic HF, 20% decrease in reinfarction
- -81- 325 mg qd
- -adverse effects- dyspepsia, bruising, bleeding, EC helps!
- 1. ASA
- 2. Clodpidrogel- antiplatelet agent, used when ASA is contraindicated, recommended for post-stent placement, 8.7% reduction in M & M as compared to ASA, rare s/e's.
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LIPID LOWERING AGENTS-
- -all CAD pts with LDL cholesterol levels greater than 100!!!!
- -STATINS are the preferred agent
- -are believed to also have anti-inflammatory and thrombetic properties
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