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 injuryA shift from aerobic to anaerobic

metabolismIncreased lactic acid

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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

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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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Used to treat coronary artery disease

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

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

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Increase blood flow to ischemic heart muscle

Decrease myocardial oxygen demand

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Minimize the frequency of attacks

Improve the client’s functional capacity

Prevent or delay heart disease

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

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

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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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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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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

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

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

Example: VerapamilSide effects◦Dizziness, flushing, supraventricular arrhythmias

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

Example◦Atenolol

Side effects◦Flushing, bradycardia, and bronchospasm

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

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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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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

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