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Analyzing angina

Ogle, Kathleen T. PhD, RN, FNP-BC

doi: 10.1097/01.NME.0000388531.96402.68
Department: Heart Matters

Graduate Program Director • Assistant Professor • Towson University • Towson, Md.

Mary Jones, 57, comes to the ED complaining of increasing fatigue over the past few weeks. On arrival, her BP is 156/92 mm Hg and she admits that she has forgotten to take her BP medication "a few times." Her heart rate is 88 beats/minute and regular, and her respiratory rate is 18 breaths/minute. She denies any chest pain, difficulty breathing, or diaphoresis. Her 12-lead ECG is normal. Mrs. Jones states that the medications she should be taking include hydrochlorothiazide, 25 mg P.O. every morning, and metformin ER, 1,000 mg P.O. at bedtime. Other than a blood glucose level of 180 mg/dL, her initial labs are within normal limits. She's resting comfortably in the ED.

Joe Smith, 65, arrives at the ED complaining of "off and on" chest pain over the past few days. He states that he "doesn't like going to the doctor" and hasn't had a physical evaluation in a few years. He was clearing his driveway after a recent snowfall and noticed that he was sweating when he had some pain. Mr. Smith denies any nausea, vomiting, dizziness, or radiation of his pain. He rates the pain, which he isn't having at present, as usually a 3 on a 0-to-10 pain scale. His BP is 138/88 mm Hg, his heart rate is 74 beats/minute and regular, and his respiratory rate is 16 breaths/minute. His 12-lead ECG has no acute changes. He doesn't take any medications and his initial labs are within normal limits.

Which patient has angina?

According to the American Heart Association, angina occurs when the myocardium doesn't get as much blood/oxygen as it needs. As a result, the patient may experience chest pain, nausea, vomiting, or diaphoresis. In the majority of cases, decreased blood flow is caused by narrowing of the coronary arteries, known as atherosclerosis. In a smaller number of cases, the cause may be diseases of the coronary valves, uncontrolled hypertension, or congenital defects.

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It takes all types

Patients are said to have stable angina, or chronic stable angina, when they have episodes of chest pain or discomfort that are predictable. This means that the pain will occur on exertion, such as running up stairs, or when under stress such as an argument with a spouse. The pain from stable angina is relieved with rest and/or nitrates.

Patients are said to have unstable angina when the chest pain they experience is unexpected, occurring while at rest or awakening them from sleep, and isn't relieved by rest or nitrates. Unstable angina typically lasts for a longer period and is greater in intensity than stable angina. Many patients with unstable angina are seen in EDs for suspected myocardial infarction (MI).

Both stable and unstable angina are most commonly caused by reduced blood flow to cardiac muscle caused by narrowing of the coronary arteries (atherosclerosis). However, there are two other types of angina with different causes. Microvascular angina, also called cardiac syndrome X, results from inadequate blood flow through the cardiac blood vessels. Prinzmetal angina, or variant angina, is caused by spasms of the coronary arteries and occurs almost exclusively while at rest (often in the middle of the night). Prinzmetal angina is particularly difficult to diagnose because cardiac catheterization may show no narrowing or blockage of the arteries (see Picturing angina).

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Digging deeper

In the office or ED setting it's difficult to differentiate patients with angina from those with acute or impending MI at first glance. Therefore, all patients who have chest pain are treated as if they're experiencing an acute event (see Comparing signs and symptoms: Unstable angina and MI). If you're caring for a patient with chest pain, take a complete history, including:

* How often does the pain occur?

* Under what circumstances does the pain occur?

* How long does the pain last?

* What helps the pain to subside?

* What's the severity of the pain?

Also ask your patients with chest pain whether they've ever had symptoms like these in the past and whether there's a family history of coronary artery disease (CAD).

In the acute care setting, the patient will undergo further testing to rule out other diagnoses, such as acute MI, pulmonary embolus, pericarditis, costochondritis (inflammation of the chest wall bones and cartilage), or pneumothorax. Lab testing can help distinguish angina from acute MI with muscle damage. Elevated levels of creatinine kinase (CK), CK-MB (or CK2) and troponin reveal damaged cardiac cells.

Mrs. Jones and Mr. Smith both had an EGG and lab testing performed on admission. In addition, many patients will be scheduled for a nuclear stress test, which can be used to reveal angina with exertion, and coronary angiography, which would show any coronary artery stenosis or obstruction.

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Medications to relieve symptoms

After the diagnosis of angina is made, you'll be teaching your patient about interventions that will help control symptoms. In addition to rest and oxygen, the patient will be given medications to help relieve symptoms. Nitrates (such as sublingual nitroglycerin) may be given to relax vascular smooth muscle and cause vasodilatation. This action can relieve and prevent attacks of angina. The most common adverse reaction to nitrates is hypotension accompanied by dizziness, so patients should be sitting or lying down when taking the medication. Nitrates may also cause headache.

When the acute phase of the angina attack is over, the patient is placed on medications to help prevent further attacks. One of the most common categories of drugs used for this purpose is beta-adrenergic receptor antagonists (also called beta-blockers). These drugs help to decrease BP and slow the heart rate, reducing the heart's demand for oxygen and therefore preventing angina. Some examples of beta-blockers are atenolol, metoprolol, and propranolol. They're indicated for the long-term prevention of angina and are often used to treat hypertension. Possible adverse reactions that you should warn your patient about include bradycardia (slow heart rate), peripheral edema, nausea and vomiting, and diarrhea. Sexual dysfunction in men is also a common adverse reaction. Beta-blockers should be avoided whenever possible in patients with a history of asthma because they may cause bronchiole constriction and in patients with high-grade atrioventricular block without a pacemaker.

When nitrates and beta-blockers don't control the pain of angina or if they're contradicted, the category of drugs called calcium channel blockers may be used. Some of the common calcium channel blockers are diltiazem, nifedipine, and verapamil. By blocking the passage of calcium ions across the myocardial cell membrane, calcium channel blockers cause dilatation of the coronary arteries and decrease the oxygen demand of the heart. These drugs are particularly effective for prevention of Prinzmetal angina. As with any drug that causes vasodilatation, one of the possible adverse reactions is hypotension. Other possible adverse reactions include dizziness, bradycardia, headache, and edema.

Another drug that's used to treat chronic angina is ranolazine, usually prescribed as 500 to 1,000 mg P.O. twice a day. Possible adverse reactions include QT prolongation, hypotension, and headache.

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Treating our patients

Both Mrs. Jones and Mr. Smith may be experiencing angina. It's important to remember that women often have atypical symptoms of angina and CAD. Many women complain only of fatigue when experiencing major coronary events. Mrs. Jones has the additional risk factors of hypertension and diabetes, which are both uncontrolled. She's treated in the ED with oxygen and nitrates, which help relieve her symptoms. She's given a prescription for atenolol to be taken daily. The nurse caring for Mrs. Jones spends time reviewing her medications and emphasizes the importance of taking all the medications as they're prescribed. Mrs. Jones promises to follow up with her healthcare provider within the next week and she's discharged home with instructions about angina.

Mr. Smith responds well to oxygen and nitrates when in the ED. But his pain reoccurs while he's walking to the bathroom. He's admitted to the coronary ICU for monitoring and evaluation. Cardiac catheterization performed after an abnormal nuclear stress test reveals some narrowing of his right coronary artery, and a stent is placed during the catheterization. He does well and is discharged on verapamil for BP and angina control 2 days later. His discharge planning includes follow-up with a healthcare provider for regular evaluation and care.

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Learn more about it

American Heart Association. Angina pectoris.
Cardiovascular Care Made Incredibly Visual! Philadelphia, PA: Lippincott Williams & Wilkins; 2007:16,164.
Nursing Pharmacology Made Incredibly Easy! Philadelphia, PA: Lippincott Williams & Wilkins; 2005:211–222.
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