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Shair Muhammad HazaraBSN, M Sc BE [DUHS]

Cardiac Disorders

Cardiac Drugs

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Cardiac Disorders

System = heart, blood vessels (arteries & veins),

Blood

Blood rich w/ O2 & nutrients moves throughvessels called arteries to narrower arteriols to

capillaries where the rich blood is absorbed by

bodies cells & waste products are absorbed (CO2,

urea, Cr, ammonia) deoxygenated blood

returned to circulation via venules to veins for

elimination through lungs & kidneys

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Cardiac disorders

Heart =

* 4 chambers - R & L atria, R & L ventricles

* Blood from circulation to R atrium to R ventricle

to pulmonary artery to lungs for gas exchange

(CO2 & O2) to L atrium to L ventricle to aorta to

systemic circulation

Heart muscle = myocardium & surrounds the atria

& ventricles

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Cardiac Disorders

Pericardium = fibrous covering around the heart

that protects it from injury & infection

Endocardium = 3-layered membrane that lines the

inner part of the heart chambers

Valves = 4 - two atrioventricular (tricuspid &

mitral) & 2 semilunar (pulmonic & aortic) -control blood. flow between atria & ventricles &

pulmonary artery & the aorta

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Right Ventricle

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Cardiac disorders

Conduction = Generated & conducted by the

myocardium - usually

* Originates in sinoatrial (SA) node - pacemaker

atrioventricular (AV) node bundle of HIS

purkinje fibers ventricular muscle tissue

contraction from apex upward forcing blood to

lungs & circulatory system

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Cardiac disorders

Blood flow & Heart Rate (HR)

* Ave. HR = 60 - 80 beats/min. (adult)

* Ave. BP = 120/80 mm/Hg - resistance to blood

flow through systemic arterial circulation

Arterial BP determined by Cardiac Output (CO) =

the volume of bld. expelled form the heart in 1

min. - calculated by mult. HR by stroke volume -

Ave. CO = 4 - 8 l/min.

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Cardiac Disorders

Stroke Volume (SV) = amt. of bld ejected from the Lvent. w/ each heart beat - Ave. = 70ml/beat

- SV determined by 3 factors:-Preload - blood flow force that stretches the ventricle

- Contractility - force of ventricular contraction

- Afterload - Resistance to vent. ejection of blood caused

by opposing pressures in aorta & systemic circulation Specific drugs can or preload & afterload, affecting

both SV & CO - most vasodilators dec. preload &afterload a dec. in arterial pressure & CO

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Cardiac Disorders

Cardiac Glycosides Digitalis - One of the oldest drugs (1200 AD)

- Effective in treating congestive heart failure

(CHF)

- CHF = when the heart muscle weakens &

enlarges loss of ability to pump blood through

the heart & into the systemic circulation = heartfailure (or pump failure)

- peripheral & lung tissues become congested =

CHF

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Cardiac Disorders

Cardiac Glycosides CHF can be left sided or right sided

Cardiac glycosides = digitalis glycosides

- inhibits the Na - K pump inc. intracellular Ca

cardiac muscle fibers contract more efficiently

- Digitalis = 3 effects on the heart 1) + inotropicaction (inc. myocard. contraction) 2) -

chronotropic action (dec. HR) #) - dromotropic

action (dec. conduction of the heart cells

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Cardiac Disorders

Cardiac Glycosides The inc. in myocardial contractility = inc. card.,

peripheral, & kidney function by inc. CO, dec.

preload, improving bld flow to periphery &kidneys, dec. edema, & inc. fluid excretion fluid

retention in lung & extremities is decreased

Digitals also used to correct atrial fibrillation &atrial flutter (cardiac dysrhythmias)

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Cardiac Disorders

Cardiac Glycosides Digoxin (Lanoxin) - Protein binding - low, t1/2 =

36 hrs - drug accumulation can occur

- monitor SE & serum levels closely

- metabolized by liver & excreted by kidneys -

kidney dysfunction can affect excretion of dig.

- Do not confuse digoxin & digitoxin

- digitoxin = highly protein bound w/ a long t1/2 -

seldom prescribed

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Cardiac Disorders

Digoxin (Lanoxin) Action = inc. myocardial contraction (+ inotrophy),

and slows HR (- chronotropy), therefore regulating the

rate & rhythm of the heart- Therapeutic serum levels = 0.5 - 2.0 ng/ml

Use = moderate/severe systolic CHF, arrythmias

SE = Dig. toxicity - bradycardia (pulse < 60), anorexia,diarrhea, N&V, blurred vision, lethargy - older adults

more prone to toxicity

DI - Other heart meds

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Cardiac Disorders

Heart Failure Other drugs =

* Vasodilators - dec. venous blood return to the heart &

dec. cardiac filling, ventricular stretching & O2 demand

* Angiotensin-converting enzyme (ACE) inhibitors - dilate

venules & arterioles & improves renal bld flow & dec. bld

fluid volume* Diruetics - first-line = reduces fluid volume

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Cardiac Disorders

Antianginal Drugs Used to treat angina pectoris ( acute cardiac pain caused

by inadequate bld flow resulting from plaque occlusion inthe coronary arteries of the myocardium or from spasmsof the coronary arteries) - described as tightness, pressurein center of chest, pain radiating down L arm - attacksmay lead to an MI

3 Types of angina pectoris

1. Classic (stable) - stress or exercise

2. Unstable (preinfarction) - frequently over day, severity

3. Variant (Prinzmetal, vasospastic) - during rest

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Cardiac Disorders

Antianginal Drugs Action - Inc. blood flow by inc. O2 supply, or by dec. O2

demand by the myocardium

Nitrates, beta-blockers, calcium channel blockers Nitrates & calcium channel blockers effective in treating

variant or vasospastic angina (not beta blockers)

beta blockers effective in treating stable angina

Non-pharm Rx = avoid heavy meals, smoking, extremes

in weather changes, strenuous exercise, stress - Proper

nutrition, moderate exercise, adequate rest & relaxation

techniques

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Cardiac Disorders

Antianginals Nitrates - First agents used - Nitroglycerine (NTG)

- Action - acts directly on the smooth muscle of blood

vessels = relaxation & dilation.- Dec. cardiac preload & afterload & reduces O2 demand

- dilation of veins = less blood return to the heart

- dilation of arteries = less vasoconstriction & resistance- Onset of Action

- sublingual (under the tongue) & IV = 1 - 3 min.

- transderm nitro patch = 30 - 60 min

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Cardiac Disorders

Antianginals SE = Headaches - less frequent w/ continued use,

hypotension, dizziness, weakness, faintness

Beta Blockers - Block the beta receptor siteAtenolol (Tenormin), Metoprolol tartrate (Lopressor),Nadolol (Corgard), Propranolol HCL (Inderal)

- Action - Dec. the effects of the sympathetic nervous

system by blocking release of epi. & norepi dec. HR &BP reduce the need for O2 & the pain of angina

- Nonselective (beta-1 & beta-2) - Inderal, Corgard, Visken

- Selective (beta -1) - Tenormin, Lopressor

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Cardiac Disorders

Antianginals SE - Dec. in HR & BP

- Closely monitor vital signs

Calcium Channel Blockers (Calcium Blockers) - Newest

Amlodipine (Norvasc), Diltiazem HCL (Cardizem),

Nifedipine (Procardia, Adalat), Verapamil (Calan,

Isoptin)

- Action - Ca activates myocard. contraction; inc. workload

of heart. Calcium blockers dec. cardiac contractility (-

inotropic) & the workload of the heart = dec. O2 need

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Cardiac Disorders

Calcium Blockers Use - long - term Rx of angina

SE - Headache, Hypotension, dizziness, flushing of the

skin- Bradycardia w/ verapamil (Calan)

- Hypotension esp. w/ Nifedipine (most potent) - promotes

vasodilation of coronary & peripheral arteries

Calcium blockers can cause changes in liver & kidney

function - Check liver enzymes periodically

Can be given w/ nitrates to prevent angina

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Cardiac Disorders

Antidysrhythmics Cardiac dysrhythmia (arrhythmia) = any deviation from

the normal rate or pattern of the heartbeat. HRs too slow(bradycardia), fast (tachycardia), or irregular

Electrocardiogram (ECG) identifies the type ofdysrhythmia

- P wave = atrial activation

- QRS complex = ventricular depolarization- T wave = ventricular repolarization

- PR interval = atrioventricular conduction time

- QT interval = ventricular action potential duration

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Cardiac Disorders

Antidysrhythmics Atrial dysrhythmias = prevent proper filling of the

ventricles & dec. CO by 1/3

Ventricular dysrhythmias = life threatening d/tineffective filling of the ventricle = dec. or absent

CO

Dysrhythmias can occur - after an MI, fromhypoxia (lack of O2 to body tissue), hypercapnia

(inc. CO2 in the bld.), excess catecholamines (epi,

norepi), or electrolyte imbalance

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Cardiac Disorders

Antidysrhythmic Drugs

2 major classifications of dysrhythmias

* Above bundle of HIS = supraventricular - A-flutter, a-fib., PACs

* Below bundle of HIS = Ventricular - PVCs, Vent. tachycardia, V-

fib. Desired action = restoration of normal cardiac rhythm

4 Classes:

1. Fast (sodium) Channel Blockers - dec. the fast Na

influx to the cardiac cells, so - dec. conduction time ofcardiac tissue, dec. likelihood of ectopic foci, inc.repolarization

- 3 subgroups of fast channel blockers

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Cardiac Disorders

Antidysrhythmics Class 1A - Procainamide (Pronestyl, Procan),

Quinidine Sulfate (Quinidex) - slows conduction &

prolongs repolarization- Use = Control PVCs, vent. tachycardia

- SE = Anorexia, headache, dizziness, weakness

Class 1B - Lidocaine (Xylocaine), Mexiletine (Mexitil) -

Slows conduction & shortens repolarization

- Use = Ventricular arrythmias associated w/ acute MIs

- IM & IV - IV bolus then a drip started (1 - 4 mg/min.)

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Cardiac Disorders

Antidysrhythmics Class 1C - Flecainide (Tambocor) - Prolongs conduction

w/ little to no effect on repolarization

- Use - Life-threatening vent. dysrhythmias,supraventricular tachycardia, a-fib or flutter

Beta Blockers - dec. conduction velocity

Prolong Repolarization - Amiodarone (Cordarone)-

emergency Rx of ventricular dysrhythmias. Inc. refractory

perios & prolong action potential duration

Calcium Channel Blockers - inc. refractory period of the

AV node, dec. vent. response

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Diuretics

Used for 2 main purposed: decrease hypertension (lower

BP), & decrease edema (peripheral & pulmonary) in CHF

and renal or liver disorders* Other uses = Dec. cerebral edema (Mannitol), dec. intraocular eye

pressure (glaucoma), dec. ascities (liver disease)

Used either singly or in combo to dec. BP & dec. edema

Diuretics produce inc. urine flow (diuresis) by inhibiting

Na & H2O reabsorption from the kidney tubules. Act on

the kidneys in diff. locations to enhance excretion of Na

(pg. 678)

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Diuretics

Every 11/2 hr. the total vol. of the bodys extracellularfluid (ECF) goes through the kidneys (glomeruli) forcleansing = 1st process for urine formation - sm. particles(electrolytes, drugs, glucose & waste) filtered in the

glomeruli Normally 99% of filtered Na passing through glomeruli

reabsorbed. 50 - 55% Na reabsorbtion in proximaltubules, 35 - 40% in loop of Henle, 5 - 10% in distal

tubules,

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Diuretics

Diuretics have an antihypertensive effect by promoting

Na & H2O loss by blocking Na/Cl reabsorption = a dec.

in fluid vol. & a dec. of BP With fluid loss - edema should decrease. When Na is

retained, H2O also retained & BP increases

Many diuretics cause loss of other electrolytes (K, Mg,

Cl, bicarb)

5 categories of diuretics:

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Action of Diuretics on Different Segments of Renal Tubules

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DiureticsThiazides/Thiazide-like Diuretics

Hydrochlorothiazide (Hydrodiuril, HCTZ),

Metolazone (Zaroxolyn)

* Action - Distal tubules of the kidney to promote Na, Cl,& H2O excretion; acts directly on arterioles, causing

vasodilation & BP; preload & CO = dec. vascular

fluid & dec. in BP

* Use - Rx of hypertension & peripheral edema

* SE - Electrolyte imbalance (hypokalemia),

hyperglycemia (inc. bld sugar), hyperlipidemia (inc. bld

lipid level), dizziness, headaches, N&V

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Diuretics

Thiazides

* CI - renal failure

* DI - Digoxin - if hypokalemia occurs, the action ofdigoxin is enhanced & dig. toxicity can occur

* Considered potassium - wasting - K supplements arefrequently prescribed & serum K levels are monitored

Loop Diuretics - Act on the ascending loop of Henle by

inhibiting Cl transport of Na into the circulation (inhibitspassive reabsorbtion of Na)

- Potent & cause marked depletion of H2O & electrolytes

- Effect = dose related - dose & response

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DiureticsLoop diuretics

More potent than thiazides as diuretics, but less effective asantihypertensive agents

Can renal bld flow up to 40%

Have a great saluretic (Na-loosing) effect & can causerapid diuresis vascular fluid vol. dec. in CO & BP

Bumetanide (Bumex), Furosemide (Lasix)- derivatives

of sulfonamides Furosemide (Lasix) -

* Use - Rx fluid retention/overload due to CHF, renaldysfunction, cirrhosis; hypertension; pulmonary edema

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DirueticsLoop Diuretics

Lasix (cont) - used when other conservative measuresfail (Na restriction & less potent diuretics)

* May be given IV or PO

* SE - Electrolyte imbalance ( esp. hypokalemia K < 3.5)& dehydration, orthostatic hypotension

* DI - digitalis preparations - dig. toxicity can result

* Nursing - Strict I & O, daily weights, vital signs,hydration status of client

* Clients should be on K supplements, monitor serum Klevels closely

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DiureticsPotassium-Sparing Diuretics

Weaker than thiazides & loop diuretics

Action - act primarily in the collecting distal duct

renal tubules to promote Na & H2O excretion & Kretention

Use - mild diuretics or in combo w/antihypertensive drugs

K supplements not used - serum potassium excess(hyperkalemia) results if K supplement taken w/potassium - sparing diuretics

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DiureticsPotassium - Sparing

Spironolactone (Aldactone), Triamterene (Dyrenium)

Aldactone (an aldosterone antagonist) - Aldosterone = amineralocorticoid hormone that promotes Na retention &K excretion; Aldosterone antagonsits inhibit the Na-K

pump (K retained & Na excreted)

Amiloride (Midamor) - antihypertensive agent

Triamterene - Rx of edema caused by CHF or cirrhosis K - sparing diuretics used alone = less effective than when

combined with reducing body fluid & Na

- Usually combine w/ a potassium wasting diuretic

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DiureticsCombination

Combine a potassium sparing & potassium wasting

diuretic = intensifies the diuretic effect & prevents K loss

spironolactone & hydrochlorothiazide (Aldactazide) amiloride & hydrochlorothiazide (Moduretic)

triamterene & hydrochlorothiazide (Dyazide, Maxide)

When diuretic combinations are used, either combined in

one tablet or as separate tablets, the dose of each isusually less than the dose of any single drug

SE = hyperkalemia - caution w/ clients having poor renal

f ti d NOT K l t ( l K l )