Agents that Dilate Coronary Blood Vessels

Coronary artery disease (CAD) results from atherosclerosis

Clinical symptoms caused by narrowing of the vessels inadequate delivery of blood, nutrients,

and oxygenLocalized muscle injuryIncreased lactic acid

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Coronary and Peripheral Artery Disease

Pain produced (angina pectoris)When the supply of oxygen and nutrients in the blood is insufficient to meet the demands of the heart, the muscle aches

Aggravated with stress or exercise

Drugs treat by dilating coronary blood vessels

Coronary and Peripheral Artery Disease

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Angina pectoris : chest painaffects ~ 9.8 million Americans/year

More prevalent in older menThe more vessels involved, the poorer the prognosis

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Angina Pectoris

Used to treat coronary artery disease

Coronary artery disease: inadequate delivery of blood, nutrients, and oxygen to the tissues

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Coronary Vasodilators

Three main objectives: ◦Minimize frequency, duration, and intensity of episodes◦Offer few side effects◦Prevent myocardial infarction—death

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Vasodilator Drug Agents

Increase blood flow to ischemic heart muscle

Decrease myocardial oxygen demand

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Therapeutic Objectives

Minimize the frequency of attacks

Improve the client’s functional capacity

Prevent or delay heart disease

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Therapeutic Objectives

Acetylsalicylic acid (ASA)NitratesCalcium channel blockers Beta blockersAngiotensin II receptor blockers

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Main Classes

Nitroglycerine◦Forms: sublingual, buccal, chewable, tablets, ointments, patches, spray, and intravenous

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Nitrates

Causes central and peripheral vasodilatation◦Relaxes smooth muscles

Potent dilating effect on coronary arteries

Used for prophylaxis and acute treatment of angina

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Nitroglycerine

Large first-pass effect when taken orally

Transdermal—very effective IV form effectively used for:◦Hypertension◦Congestive heart failure◦Ischemic pain, myocardial infarction ◦Pulmonary edema

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Nitroglycerin

Do not leave the patient when he or she is changing positions after starting a new prescription for nitro◦Nitroglycerin is intended to cause rapid vasodilation -> dizziness with position change◦Nitro paste: remove med from patient’s skin and wash/dry before reapplying◦Always wear gloves when applying nitro topically

Nitro: nursing considerations

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Example of long-acting nitrate◦Isosorbide dinitrate (Isordil)

Provides:◦Acute relief of angina

◦Long-term prophylaxis of angina

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Nitrates

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General Side Effects Headache

Diminish in intensity and frequency with use

Tachycardia Postural hypotension Dermatitis Tolerance

Long-acting form can become ineffective

Solution◦Remove patch or cream at night for 8 hours◦Take the oral form for 16 hours a day

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Tolerance to Nitrates

Additive hypotension with use of:◦Alcohol◦Beta blockers◦Calcium channel blockers◦Phenothiazines

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Interactions

Reduces calcium ion influx:◦Reduction of myocardial oxygen consumption◦Coronary artery dilation

Example: VerapamilSide effects◦Dizziness, flushing, supraventricular arrhythmias

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Calcium Channel Blockers

Block the beta receptors◦Reduce heart rate ◦Reduce contractility◦Reduce blood pressure

Example◦Atenolol

Side effects◦Flushing, bradycardia, and bronchospasm

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Beta-adrenergic Blocking Agents

Angiotensin II receptor blockers◦Block adrenergic receptors, or ◦Direct action Interfere with epinephrine action

Sympathetic nervous system is not stimulated◦Result: decreased blood pressure

Side effects◦Orthostatic hypotension

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Peripheral Vasodilators

Inhibits platelet clumping◦Given as a preventive agent◦Given when a person is experiencing a myocardial infarction

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Aspirin

Patients should carry IDTeach smoking/tobacco cessation, med use

Assess angina attacksTeach: nitroglycerine (NTG) most effective when taken at the beginning of an angina episode

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Nursing Considerations

Teach: replace sublingual NTG Q 3 months

IV NTG requires special preparation: glass, not plastic

Give beta-blocking agents before vasodilators

Monitor blood pressure routinely

Nursing considerations

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