Drugs Affecting Cardiac and Renal Systems

Jan Bazner-Chandler

MSN, CNS, C-PNP, RN

Positive Inotropic Drugs

Chapter 21

Inotropic Drugs

Drugs that increase the force of myocardial contractions.

Chronotropic Drugs

Drugs that increase the rate at which the heat beats.

Dromotropic Drugs

Drugs that accelerate conduction.

Heart Failure

Congestive heart failure (CHF), or heart failure (HF), is a condition in which the heart can't pump enough blood to the body's other organs.

Causes of Heart Failure

narrowed arteries that supply blood to the heart muscle — coronary artery disease (CAD)

past heart attack, or myocardial infarction (MI), with scar tissue that interferes with the heart muscle's normal work

high blood pressure heart valve disease primary disease of the heart muscle itself, called cardiomyopathy. heart defects present at birth — congenital heart defects. infection of the heart valves and/or heart muscle

itself — endocarditis and/or myocarditis

CAD

Heart Valve Disease

Endocarditis

Heart Failure

As blood flow out of the heart slows, blood returning to the heart through the veins backs up, causing congestion in the tissues. Often swelling (edema) results. Most often there's swelling in the legs and ankles, but it can happen in other parts of the body, too. Sometimes fluid collects in the lungs and interferes with breathing, causing shortness of breath, especially when a person is lying down.

Heart Failure

Signs and Symptoms of Heart Failure or HF Often no symptoms at rest Dyspnea (difficulty breathing) and fatigue

occur with increased activity Edema of ankles and feet Distention of jugular veins In acute cases pulmonary edema – cough

and shortness of breath

Pitting Edema

Distended Jugular Vein

Drugs in first-line treatment

Digoxin Diuretics ACE Angiotension-converting enzyme

inhibitors

Cardiac Glycosides

Oldest and most effective group of cardiac drugs.

Comes from the plant “fox glove”.

Cardiac Glycosides or Digoxin Digoxin or Lanoxin is the only commonly

used digitalis glycoside.

digoxin (Lanoxin, Digitek)

Classification Pharmacologic: digitalis, glycoside

Classification Therapeutic: antiarrhythmic, inotropic

Actions

Digoxin improves the pumping ability of the heart Increases the force of myocardial contraction by

inhibiting the Na, K-adenosine triphosphatase, an enzyme in cardiac cell membrane that decreases the movement of sodium out of myocardial cell after contraction.

Calcium enters the cell in exchange for sodium. The calcium activates the contractile proteins and

increased myocardial contractility.

Administration

Can be given orally or IV IV peaks within 10 to 30 minutes PO peaks within 1 to 2 hours

Serum Blood Levels

Maximum drug action occurs when steady tissue concentration has been achieved – takes about 1 week

Loading dose or digitalizing dosage will be higher until the therapeutic level has been reached.

Dosage 0.75 to 1.5 mg every 6 to 8 hours When adequate levels have been reached

than a maintenance dose can be started

Maintenance Dose

Dosing is 0.125 – 0.5 mg Average dose is 0.25 mg Take daily at same time of day Give with food or after meals

Dosing by mcg/kg in Adults

IV digitalizing dose = 0.6 to 1 mg (10 -15 mcg/kg) given at 50% initially and additional fractions given at 4-8 hour intervals.

PO adults digitalizing dose 0.75 – 1.25 mg (10 – 15 mcg/kg)

PO children digitalizing dose 10 to 15 mcg/kg

Nursing Responsibilities

Take apical pulse for one full minute before giving the medication – listen for any irregular heart beats

Specific guidelines for holding the drug and notifying physician Adults: apical pulse less than 60 Older child: apical pulse less than 60 Infant or younger child: apical pulse less than 100

Nursing Responsibilities

Notify physician if bradycardia (heart rate less than 60 bpm) or new arrhythmias occur.

Assess for peripheral edema and auscultate lungs for rales/crackles.

Check kidney function since you want to know they can excrete excess digoxin and avoid build up in body.

Laboratory Values

Electrolyte imbalance: potassium, calcium and magnesium values need to be monitored

Hypokalemia (low potassium) Hypomagnesemia (low magnesium) Both can lead to irregular heart rate.

Digoxin Toxicity

Anorexia, nausea, and confusion are symptoms of digoxin toxicity

HR below 60 in adults and HR below100 in infants and small children

Digoxin should be discontinued by MD only– takes about 1 week for drug to be eliminated from the body.

Evaluation of Effectiveness

Increased urinary output Decreased edema Decreased shortness of breath, dyspnea and

crackles Decreased fatigue Improved peripheral pulses, skin color and

temperature Serum digoxin levels 0.5 to 2 ng/mL

digoxin Overdose

digoxin immune Fab or DigiFab Therapeutic classification: antidotes Pharmacologic classification: antibody fragments Indications: serious life-threatening over dosage

with digoxin. Action: An antibody produced in sheep that binds

anti-genetically to unbound digoxin in serum. Therapeutic effect: Binding and subsequent removal

of digoxin, preventing toxic effects in overdose.

Antianginal Drugs

Chapter 23

Coronary Arteries

Arteries that deliver oxygen to the heart muscle.

Coronary Arteries

Angina Pectoris

Chest pain occurring when the heart’s supply of blood carrying oxygen and energy-rich nutrients is insufficient to meet demands of the heart.

Ischemia

Poor blood flow to an organ Ischemic heart disease = poor blood flow to

heart Myocardial infarct = damage done to heart

muscle after an ischemic event

Angina

Angina pectoris is a clinical symptoms characterized by episodes of chest pain.

There is deficit in myocardial oxygen supply (myocardial ischemia) in relation to myocardial oxygen demand.

Pain can be caused by coronary vasospasm

Angina

Angina

Classification of Angina

Class I: ordinary physical activity does not cause angina – strenuous activity only.

Class II: angina occurs with walking or climbing stairs rapidly or up hill.

Class III: marked limitation in ordinary daily activity.

Class IV: anginal symptoms may be present at rest.

Antianginal Drugs

Nitrates are used to treat and prevent attack of angina.

Only nitrates can be used in the acute treatment of angina pectoris.

Calcium channel blockers and beta blockers are used prophylactically (to prevent) or in long-term management of angina.

nitroglycerine

Classification Pharmacologic: nitrates Classification Therapeutic: antianginals

nitroglycerine

Action: Increases coronary blood flow by dilating coronary arteries and improving collateral flow to ischemic regions. Decreases left ventricular end-diastolic pressure and left ventricular end-diastolic volume. Reduces myocardial oxygen consumption.

Therapeutic effects: Relief or prevention of anginal attacks Reduction of blood pressure Increase blood flow to heart / decrease in HR

Dosing

Oral dosage is rapidly metabolized in the liver and only small doses reach the systemic circulatory system

For more effective absorption drug is given: Sublingually – under the tongue – acts in 1 to 3 minutes PO: sustained-released tablet Transdermal ointments – applied on hairless area on back,

chest or upper arm Patches – takes 40 minutes to an hour to start working

Sublingual Nitroglycerine

Sublingual Administration

Tablet should be held under tongue until dissolved. Avoid eating, drinking, or smoking until tablet is dissolved.

Acute anginal attacks: Advise patient to sit down. Relief should occur in 1 to 3 minutes May be repeated every 5 minutes for 3 doses. If no relief call 911.

Sustained Released Tablet

Sustained Released Tablet

Administer dose 1 hour before or 2 hours after meal with a full glass of water for faster absorption.

Note: Sustained released preparations should be swallowed whole, do not crush, break or chew.

Nitroglycerine Patch

Nitroglycerin Patch

Place the patch on a hairless area of chest or upper arm each day.

Move patch to a different place on your body each day to prevent skin irritation.

Remove the patch for 8 to 12 hours each night and put on a fresh patch each day.

Do not leave on all the time. Remove for defibrillation

Nitroglycerine Ointment

Nitroglycerine Ointment

Comes with paper with a ruled line for measuring the dose

Squeeze ointment onto the paper, carefully measuring the amount specified on the prescription label

Use the paper to spread ointment in a thin layer on a hair-free area of skin (2 by 3 inches)

Keep paper in place with bandage or tape Ointment is applied three or four times a day

Side Effects

Dizziness Headache Hypotension Tachycardia Syncope

Antiaginal Drugs

Nitrates to manage the chest pain Beta blockers to manage the chest pain plus

hypertension Calcium channel blockers to manage the

chest pain plus hypertension

Blood Pressure Medications

ACE inhibitors: angiotension-converting enzyme inhibitors

Beta blockers Calcium channel blockers Diuretics Vasodilators: used in hypertensive crisis only

B-adrenergic Blockers

B-blockers (beta 1) Primary drug effect is related to the

cardiovascular system.

When Used

Angina Myocardial infarct Dysrhythmias Hypertension Used when a client has a combination of any

of the above diagnoses

Action of Beta 1 Blockers

Decrease energy demands on heart to decrease angina attacks.

Block the B receptors on the SA node to slow heart rate

Block the harmful release of catecholamines (epinephrine and norepinephrine)

Blocks the release of renin a potent vasoconstrictor in the kidney to decrease blood pressure.

Contraindications

Systolic heart failure Systolic cardiac (heart) dysfunction (or

systolic heart failure) occurs when the heart muscle doesn't contract with enough force, so there is not enough oxygen-rich blood to be pumped throughout the body.

Contraindications

Conductive disturbances Bronchial asthma Diabetes: blocks hypo-glycemic induced

tachycardia. Reduced metal alertness Peripheral vascular disease

Adverse Effects

Decrease in HR blow the 60 bpm Decreased cardiac output Bronchocontriction in patients with asthma or

COPD. Cardiac rhythm problems due to decreased

SA or AV node conduction Hypo or hyperglycemia Hypotension

Nursing Responsibilities

Monitor blood pressure Assess for orthostatic hypotension when a

client stands up Check medication refills for adherence Assess for angina Monitor for signs of overdose

Beta Blocker Drugs

Three most common drugs used carvedilol or Coreg metoprolol or Lopressor atenolol or Tenormin

Clinical Pearl

Beta blockers are good to use in clients who like to exercise.

It does not allow the heart rate to elevate to dangerous levels

Client may report inability to generate a increase heart rate while exercising

Calcium Channel Blockers

Three chemical classifications phenylalkylamines benzothiazepines dihydrophyridines

Action

Block calcium entry into cells of vascular smooth muscle an myocardium. Dilate coronary arteries in both normal and ischemic myocardium and inhibit coronary artery spasm.

Increased blood flow to ischemic heart Useful in treating dysrhythmias

Indications

First line drugs used to treat Angina Hypertension Supraventricular tachycardia: cardiac dysrhythmia

One Important Consideration When Prescribing Calcium Channel Blockers may not be as

effective in controlling exercise induced elevation of heart rate or blood pressure.

A beta 1 blocker would be best for the client that exercises – drug would keep heart rate and blood pressure from rising during exertion.

Contraindications

Drug allergy Acute Myocardial Infarction (MI) Atrial ventricular block

Bradycardia Pacemaker

Hypotension

Adverse Effects

Cardiovascular: Hypotension Heart palpitations Tachycardia / bradycardia Heart Failure

ACE Inhibitors – Angiotensin Receptor Antagonists Lotensin Capoten Vasotec Accupril Altace Mavik

ACE inhibitors

Indication: used alone or with other agents in the

management of hypertension used in patients with congestive heart failure

Action: blocks the vasoconstrictor and aldosterone

producing effects of angiotensin II at various receptor sites, including vascular smooth muscle and the adrenal glands.

ACE Inhibitors

Therapeutic Effects: Lowering of blood pressure Decreased after load in patients with Congestive

Heart Failure Decreased development of Heart Failure Increased survival after Myocardial infarct Decreased progression of diabetic neuropathy

Evaluation of Effectiveness

Decrease in blood pressure Decrease in signs and symptoms of CHF Reduction of risk of developing CHF

(congestive heart failure) after a MI (myocardial infarct)

Nursing Responsibilities

Monitor blood pressure Monitor for signs of fluid overload

Monitor weight Edema Jugular distension Lung congestion

Monitor frequency of prescription refills to determine adherence

Most common side effect

Cough Hyperkalemia (due to decrease in secretion

of potassium) Metallic taste

Vasodilators

Action: works directly on arteriolar and venous muscles to cause relaxation.

Very useful in managing hypertensive emergencies.

Blood pressure needs to be brought down slowly.

Vasodilators

Intravenous (IV) diazoxide and sodium nitroprusside are useful in managing hypertensive emergencies.

Blood pressure need to be brought down slowly.

Nursing Responsiblities

Monitor for adverse effects: Orthostatic hypotension Dizziness fatigue

Nursing Assessment

Monitor effectiveness of the drug therapy Client will return to baseline activities Client will report improved energy. Blood pressure reading will be lowered with the

goal to bring back to normal levels.