Coronary artery disease




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CORONARY ARTERY DISEASE

Coronary artery disease (CAD) is a disease characterized by the accumulation of plaque within the layers of the coronary arteries. The plaques progressively enlarge, thicken, and calcify, causing a critical narrowing (75% occlusion) of the coronary artery lumen, resulting in a decrease in coronary blood flow and an inadequate supply of oxygen to the heart muscle.
Acute coronary syndromes (ACS) is a term used to define potential complications of CAD. This syndrome includes unstable angina, non-ST-segment elevation myocardial infarction (MI), and ST-segment elevation MI.

Angina Pectoris
- Angina pectoris, or chest pain, caused by myocardial ischemia is not a separate disease, but rather a symptom of CAD. It is caused by a blockage or spasm of a coronary artery, leading to diminished myocardial blood supply.

Pathophysiological Principles
- It is caused by transient, reversible myocardial ischemia precipitated by an

imbalance between myocardial oxygen demand and myocardial oxygen

supply.




Causes of reduced oxygen supply



Causes of increase in oxygen demand

- Atherosclerotic narrowing of the

coronary arteries.

- Intense focal spasm of a coronary artery.

- Arterial inflammation

- Fever,

- Tachycardia,

- Thyrotoxicosis




Classification of Angina
1- Stable angina, also known as chronic stable angina, classic angina, or

exertional angina,
- Paroxysmal sub-sternal pain that is usually predictable.

- The pain occurs with physical exertion or emotional stress

- The pain is relieved by rest or nitroglycerin.
2- Unstable angina, also called preinfarction angina or crescendo angina,
- Cardiac chest pain that usually occurs while at rest.

- More prolonged and severe chest discomfort than with stable angina.

- Unstable angina is a type of acute coronary syndrome and requires

immediate treatment because the patient is at increased risk for :-

1 - Acute MI,

2 - Cardiac dysrhythmias,

3 - Cardiac sudden death.

3- Variant angina, also know as Prinzmetal’s angina or vasospastic angina, is a form of unstable angina.

- Usually occurs at rest, most often between midnight and 8 AM.

- It does not usually occur after exertion or emotional stress.

- It is the result of coronary artery spasm.

- Most people who experience variant angina have severe coronary

atherosclerosis of at least one major coronary artery and the spasm occurs

very near the area of blockage.
Assessment
History
A description of the symptoms, information about a prior history of

coronary artery disease, the patient’s sex and age, and the number of risk factors present.


The N, O, P, Q, R, S, T characteristics of chest pain due to Myocardial ischemia
N—Normal
- The patient’s baseline before the onset of the pain
O—Onset
- The time when the pain/discomfort started
P—Precipitating and Palliative ( relieving ) Factors
Precipitating factors:-
- Exercise

- Exercise after a large meal

- Exertion

- Walking on a cold or windy day

- Cold weather

- Emotion such as stress or anxiety, anger, fear


Palliative ( relieving ) factors (Any measures the patient has used to relieve the pain)
- Stop exercise.

- Sit down and rest.

- Use sublingual nitroglycerin; pain of myocardial infarction is often not

relieved by sublingual nitroglycerin.


N.B:-
- As the angina becomes more severe (unstable angina), the pain may occur

at rest or be caused by less exertion and is no longer relieved with rest or

sublingual nitroglycerin.
Q—Quality
- Heaviness

- Tightness

- Squeezing

- Choking

- Suffocating

- Viselike

- Smothering sensations.

- Deep, poorly localized chest or arm discomfort.


R—Region and Radiation
- Substernal , left sided chest with radiation to the back, left arm, neck, back

or jaw


- Upper chest

- Epigastric

- Left shoulder

- Intrascapular


S—Severity
- Pain rated on a scale of 1 to 10, with 10 being the worst pain ever

experienced, often rated as 5 or above




T—Time
- The nurse asks how long the pain lasts, how frequently it occurs, and

the time of day it occurs.


- Pain lasts from 30 seconds to 30 minutes.
N.B:-
- Pain can last longer than 30 minutes for unstable angina or myocardial

infarction.
- Finally, the nurse asks about associated symptoms such as dyspnea,

nausea, vomiting, and diaphoresis.


Physical Examination
- The physical examination helps to


  1. Determine the cause of the pain,

  2. Detect comorbid conditions,

  3. Assess any hemodynamic consequences of the pain.

- Tachycardia and pulsus alternans. measure the blood pressure

in both arms

- Hypertension during the initial phase of an anginal episode.

- Pallor with cold, clammy skin.

- Xanthomas on skin , which are yellow nodules or plaques, especially on

the skin. Xanthomas may be indications of hypercholesterolemia.

- Carotid or femoral bruits on auscultation, indicating the possible

presence of obstructive cardiovascular disease.

- A paradoxical split of S2 or an S3 heart on auscultation sound. Both sounds

are indicators of left ventricular failure.

- An S4 may be heard, which is suggestive of decreased left ventricular

compliance.

- Deficits in peripheral pulses may indicate peripheral vascular disease.


Diagnostic Tests
- A 12-lead electrocardiogram (ECG) should be obtained immediately in

patients with chest discomfort.


- During the anginal episode, the ECG may show in the ECG leads

associated with the anatomical region of myocardial ischemia

A- T-wave inversions

B - ST segment depressions


- Transient ST segment changes (≥0.05 mV) that occur during a

symptomatic episode while at rest and that resolve when the patient is

a symptomatic are highly suggestive of severe coronary artery disease.
- Ectopic beats may also be present during an anginal episode.
- The ECG should be compared with previous ECGs.
- The ECG may appear normal between anginal episodes,

- Ambulatory ECG monitoring may be used to assist in the diagnosis of

angina, especially for patients who have angina at rest.
- Biochemical cardiac markers are useful in determining both the diagnosis

and the prognosis of acute coronary syndromes.


- A cardiac-specific troponin (troponin T or troponin I) is the preferred

marker to obtain in all patients who present with chest discomfort

consistent with acute coronary syndrome. The creatine kinase with

myocardial bands (CK-MB) is an acceptable marker to use. If the patient

has a negative cardiac marker within 6 hours of the onset of chest

discomfort, another sample should be drawn in the 6- to 12-hour period

after onset of chest discomfort.
- Additional blood tests include chemistry, complete blood count, and

coagulation studies.


- Exercise stress testing in which the ECG and blood pressure are monitored

before, during, and after exercise.

- For patients who are unable to exercise, pharmacological stress testing

may be done in which the medication increases myocardial oxygen demand

while the patient remains inactive. Intravenous medications used for

pharmacological stress testing include adenosine, dobutamine, and

dipyridamole.
- Cardiac imaging studies usually start with chest radiographs, although they

have limited value in diagnosing coronary heart disease.


- Thallium-201 or technetium-99m sestamibi perfusion imaging can be used

with exercise or pharmacological stress testing to detect perfusion defects.


- Positron emission tomography (PET):( The patient either inhales or receives by injection radioactively tagged substances, such as oxygen or glucose.

A gamma scanner measures the radioactive uptake of these substances, and a computer produces a composite image, indicating where the radioactive material is located, corresponding to areas of cellular metabolism).

May be helpful in differentiating ischemic from infarcted myocardium.
- Echocardiography is performed to evaluate wall motion abnormalities and

thickness, valvular function, and ejection fraction.


- Magnetic resonance imaging (MRI) may be used to view structural

cardiovascular abnormalities when other diagnostic techniques (e.g., the

echocardiogram) are inconclusive or ambiguous.
- Coronary angiography is an invasive diagnostic test that provides a

definitive diagnosis of coronary artery disease.

- Results from coronary angiography are used to guide the decision whether

to manage the patient medically or surgically.


Management
- The goal of therapy for the patient with angina pectoris is to restore the

balance between oxygen supply and oxygen demand.



Morphine sulfate is indicated for patients whose symptoms are not relieved after three serial sublingual nitroglycerin tablets or whose symptoms recur with adequate anti-ischemic therapy.

  • The nurse carefully monitors the patient’s respiratory rate and blood pressure, especially if the patient continues to receive IV nitroglycerin.

Beta blockers may be used to decrease myocardial oxygen consumption by reducing myocardial contractility, sinus node rate, and atrioventricular (AV) node conduction velocity.

  • Beta blockers are started by an IV route, followed by oral administration.

Calcium antagonists : decrease myocardial oxygen demand by decreasing afterload, contractility, and heart rate. Verapamil or diltiazem can be used as second- or third-choice therapy after the initiation of nitrates and beta blockers.

  • Verapamil or diltiazem can be given as initial therapy when beta blockers are contraindicated

Antiplatelet therapy should be initiated promptly for the patient with unstable angina.

  • Aspirin is administered as soon as possible and is continued indefinitely unless contraindicated.

  • A second class of antiplatelet drugs known as thienopyridines can be used in patients with unstable angina.

  • Clopidogrel (Plavix) is the preferred drug in this class because of its rapid onset of action and safety profile.

  • Clopidogrel is used for patients who are unable to tolerate aspirin. The drug is also recommended for hospitalized patients in addition to aspirin unless the patient is scheduled for coronary artery bypass grafting surgery.

  • A third group of antiplatelet drugs known as glycoprotein IIb/IIIa antagonists such as Tirofiban (Aggrastat) are used for patients with unstable angina who are undergoing percutaneous coronary interventions.

  • Anticoagulation with low– molecular-weight heparin or IV unfractionated heparin should be added to antiplatelet therapy, such as clexane.


INVASIVE THERAPY

  • Invasive therapy may be indicated for the management of patients with unstable angina.

  • Intra-aortic balloon pump support may be used in a critically ill patient to provide increased coronary artery perfusion and to decrease afterload.

  • Percutaneous transluminal coronary angioplasty and stent placement may be used for treating patients with unstable angina.

  • Coronary artery bypass grafting is another invasive options for treatment


RISK FACTOR MODIFICATION

  • Risk factor modification may help prevent an anginal episode or delay the worsening of existing angina.

  • Patients should be encouraged to stop smoking, achieve or maintain optimal weight, and exercise daily.

  • Diet and medications may be prescribed to control hypertension, diabetes, and hyperlipidemia.

  • Patient education, including home care considerations, is essential for patients with angina pectoris.


Nursing Diagnoses

  • Acute Pain related to an imbalance in oxygen supply and demand

  • Decreased Cardiac Output related to reduced preload, afterload, contractility, and heart rate secondary to hemodynamic effects of drug therapy

  • Anxiety related to chest pain, uncertain prognosis, and threatening environment


Nursing Interventions

Relieving Pain



  • Determine intensity of patient's angina.

    • Ask patient to compare the pain with other pain experienced in the past and, on a scale of 0 (no pain) to 10 (worst pain), rate current pain.

    • Observe for other signs and symptoms, including diaphoresis, shortness of breath, protective body posture, dusky facial color, and/or changes in level of consciousness (LOC).

  • Position patient for comfort; Fowler's position promotes ventilation.

  • Administer oxygen if prescribed.

  • Obtain BP, apical heart rate, and respiratory rate.

  • Obtain a 12-lead ECG as directed.

  • Administer antianginal drug as prescribed.

  • Report findings to health care providers.

  • Monitor for relief of pain, and note duration of anginal episode.

  • Take vital signs every 5 to 10 minutes until angina pain subsides.

  • Monitor for progression of stable angina to unstable angina: increase in frequency and intensity of pain, pain occurring at rest or at low levels of exertion, pain lasting longer than 15 minutes.

  • Determine level of activity that precipitated anginal episode.

  • Identify specific activities patient may engage in that are below the level at which anginal pain occurs.

  • Reinforce the importance of notifying nursing staff when angina pain is experienced.


Maintaining Cardiac Output

  • Carefully monitor the patient's response to drug therapy.

    • Take BP and heart rate in a sitting and a lying position on initiation of long-term therapy (provides baseline data to evaluate for orthostatic hypotension that may occur with drug therapy).

    • Recheck vital signs as indicated by onset of action of drug and at time of drug's peak effect.

    • Note changes in BP of more than 10 mm Hg and changes in heart rate of more than 10 beats/minute.

    • Note patient complaints of headache (especially with use of nitrates) and dizziness.

      • Administer or teach self-administration of analgesics as directed for headache.

      • Encourage supine position to relieve dizziness (usually associated with a decrease in BP; preload is enhanced by this mechanism, thereby increasing BP).

    • Institute continuous ECG monitoring or obtain 12-lead ECG as directed. Interpret rhythm strip every 4 hours for patients on continuous monitoring (beta-adrenergic blockers and calcium channel blockers can cause significant bradycardia and varying degrees of heart block).

    • Evaluate for development of heart failure (beta-adrenergic blockers and some calcium channel blockers decrease contractility, thus increasing the likelihood of heart failure).

      • Obtain daily weight and intake and output.

      • Auscultate lung fields for crackles.

      • Monitor for the presence of edema.

    • Monitor laboratory tests as indicated.

  • Be sure to remove previous nitrate patch or paste before applying new paste or patch (prevents hypotension). To decrease nitrate tolerance transdermal nitroglycerin may be worn only in the daytime hours and taken off at night when physical exertion is decreased.

  • Be alert to adverse reaction related to abrupt discontinuation of beta-adrenergic blocker and calcium channel blocker therapy. These drugs must be tapered to prevent a “rebound phenomenonâ€‌: tachycardia, increase in chest pain, hypertension.

  • Discuss use of chromotherapeutic therapy with health care provider (tailoring of antianginal drug therapy to the timing of circadian events).

  • Report adverse drug effects to health care provider.


Decreasing Anxiety

  • Rule out physiologic etiologies for increasing or new onset anxiety before administering as needed sedatives. Physiologic causes must be identified and treated in a timely fashion to prevent irreversible adverse or even fatal outcomes; sedatives may mask symptoms delaying timely identification and diagnosis and treatment.

  • Assess patient for signs of hypoperfusion, auscultate heart and lung sounds, obtain a rhythm strip, and administer oxygen as prescribed. Notify the health care provider immediately.

  • Document all assessment findings, health care provider notification and response, and interventions and response.

  • Explain to patient and family reasons for hospitalization, diagnostic tests, and therapies administered.

  • Encourage patient to verbalize fears and concerns about illness through frequent conversations: conveys to patient a willingness to listen.

  • Answer patient's questions with concise explanations.

  • Administer medications to relieve patient's anxiety as directed. Sedatives and tranquilizers may be used to prevent attacks precipitated by aggravation, excitement, or tension.

  • Explain to patient the importance of anxiety reduction to assist in control of angina. (Anxiety and fear put an increased stress on the heart, requiring the heart to use more oxygen.) Teach relaxation techniques.

  • Discuss measures to be taken when an anginal episode occurs. (Preparing patient decreases anxiety and allows patient to accurately describe angina.)

    • Review the questions that will be asked during anginal episodes.

    • Review the interventions that will be employed to relieve anginal attacks.


Patient Education and Health Maintenance

Instruct Patient and Family About CAD



  • Review the chambers of the heart and the coronary artery system, using a diagram of the heart.

  • Show patient a diagram of a clogged artery; explain how the blockage occurs; point out on the diagram the location of the patient's lesions.

  • Explain what angina is (a warning sign from the heart that there is not enough blood and oxygen because of the blocked artery or spasm).

  • Review specific risk factors that affect CAD development and progression; highlight those risk factors that can be modified and controlled to reduce risk.

  • Discuss the signs and symptoms of angina, precipitating factors, and treatment for attacks. Stress to patient the importance of treating angina symptoms at once.

  • Distinguish for patient the different signs and symptoms associated with stable angina versus preinfarction angina.


Identify Suitable Activity Level to Prevent Angina

Advise the patient about the following:



  • Participate in a normal daily program of activities that do not produce chest discomfort, shortness of breath, and undue fatigue. Spread daily activities out over the course of the day, avoid doing everything at one time. Begin regular exercise regimen as directed by health care provider.

  • Avoid activities known to cause anginal pain: sudden exertion, walking against the wind, extremes of temperature, high altitude, emotionally stressful situations; these may accelerate heart rate, raise BP, and increase cardiac work.

  • Refrain from engaging in physical activity for 2 hours after meals. Rest after each meal if possible.

  • Do not perform activities requiring heavy effort (eg, carrying heavy objects).

  • Try to avoid cold weather if possible; dress warmly and walk more slowly. Wear scarf over nose and mouth when in cold air.

  • Reduce weight, if necessary, to reduce cardiac load.


Instruct About Appropriate Use of Medications and Adverse Effects

  • Carry nitroglycerin at all times.

    • Nitroglycerin is volatile and is inactivated by heat, moisture, air, light, and time.

    • Keep nitroglycerin in original dark glass container, tightly closed to prevent absorption of drug by other pills or pillbox.

    • Nitroglycerin should cause a slight burning or stinging sensation under the tongue when it is potent.

  • Place nitroglycerin under the tongue at first sign of chest discomfort.

    • Stop all effort or activity; sit, and take nitroglycerin tablet:relief should be obtained in a few minutes.

    • Bite the tablet between front teeth and slip under tongue to dissolve if quick action is desired.

    • Repeat dosage in a few minutes for total of three tablets if relief is not obtained.

    • Keep a record of the number of tablets taken to evaluate change in anginal pattern.

    • Take nitroglycerin prophylactically to avoid pain known to occur with certain activities.

  • Demonstrate for patient how to administer nitroglycerin paste correctly.

    • Place paste on calibrated strip.

    • Remove previous paste on skin by wiping gently with tissue.

    • Rotate site of administration to avoid skin irritation.

    • Apply paste to skin; use plastic wrap to protect clothing if not provided on strip.

    • Have patient return demonstration.

  • Instruct patient on administration of transdermal nitroglycerin patches.

    • Remove previous patch; wipe area with tissue to remove any residual medication.

    • Apply patch to a clean, dry, nonhairy area of body.

    • Rotate administration sites.

    • Instruct patient not to remove patch for swimming or bathing.

    • If patch loosens and part of it is nonadherent, it should be discarded and a new patch applied.

  • Teach patient about adverse effects of other medications.

    • Constipation: verapamil (Calan)

    • Ankle edema: nifedipine (Procardia)

    • Heart failure (shortness of breath, weight gain, edema)”beta-adrenergic blockers or calcium channel blockers

    • Dizziness: vasodilators, antihypertensives

  • Ensure that patient has enough medication until next follow-up appointment or trip to the pharmacy. Warn against abrupt withdrawal of beta-adrenergic blockers or calcium channel blockers to prevent rebound effect.


NURSING ALERT

Instruct patient to go to the nearest health facility if chest pain persists for more than 15 minutes, is unrelieved by three nitroglycerin tablets, or is more intense and widespread than the usual angina episodes. (Patient should not drive self.)


Counsel on Risk Factors and Lifestyle Changes

  • Inform patient of methods of stress reduction, such as biofeedback and relaxation techniques.

  • Review low-fat and low-cholesterol diet. Explain AHA guidelines, which recommend eating fish at least twice a week, especially fish high in omega-3 oils.

    • Omega-3 oils have been shown to improve arterial health and decrease BP, triglycerides, and the growth of atherosclerotic plaque.

    • Omega-3 oils can be found in fatty fish, such as mackerel, salmon, sardines, herring, and albacore tuna.

    • Suggest available cookbooks (AHA) that may assist in planning and preparing foods.

    • Have patient meet with dietitian to design a menu plan.

  • Inform patient of available cardiac rehabilitation programs that offer structured classes on exercise, smoking cessation, and weight control.

  • Avoid excessive caffeine intake (coffee, cola drinks), which can increase the heart rate and produce angina.

  • Do not use diet pills,‌ nasal decongestants, or any over-the-counter medications that can increase the heart rate or stimulate high BP.

  • Avoid the use of alcohol or drink only in moderation (alcohol can increase hypotensive adverse effects of drugs).

  • Encourage follow-up visits for control of diabetes, hypertension, and hyperlipidemia.

  • Have patient discuss supplement therapy (ie, vitamins B6, B12, C, E, folic acid, and L-arginine) with health care provider.


Evaluation: Expected Outcomes

  • Verbalizes relief of pain

  • Blood pressure and heart rate stable

  • Verbalizes lessening anxiety, ability to cope




Dr. Abdul-Monim Batiha - Assistant Professor Of Critical Care Nursing



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