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
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.
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
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.
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
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 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 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.
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
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.
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.
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 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.