Article Analysis – 12-Lead ECG Interpretation Questions

Questions (points possible)

Answers                                                                              Use concise, complete sentences. Do not exceed 1 page.

Identify causes and risk factors for the acute coronary syndrome (ACS) and acute myocardial infarction (AMI) the nurse should recognize in the scenario. (10 points)

ACS – Acute coronary syndrome is a collection of clinical and pathophysiologic findings associated with an acute and reversible change in myocardial perfusion. ACS includes instability involving angina, “non-ST-segment (NSTEMI), and ST-segment elevation myocardial infarction (STEMI)” (Haider et al., 2020).

AMI – Acute myocardial infarction (AMI) is a syndrome resulting from an acute thrombotic event involving the wall of an artery supplying blood to the heart muscle; it is characterized by symptoms and signs associated with myocardial dysfunction, necrosis, and rupture. The exact etiology is unknown.

Causes and Risk Factors

- Smoking - smoking cigarettes since the age of 18.

- Obesity - the patient is obese and has HTN, GERD, CAD, and Diabetes.

-Hypertension: over 140/90 mm Hg at potential or on minimal exertion or treatment with antihypertensive medications.

- Hyperlipidemia - elevated LDL cholesterol or triglycerides (Majorowiz et al., 2019).

-Diabetes mellitus: Blood glucose greater than 200 mg/dl.

-Atherosclerosis

-Family history of premature cardiovascular disease (CVD), diabetes mellitus

Regularity and rate: For the 12-lead electrocardiogram (ECG), describe the regularity and calculate the heart rate. the large or small box method. (15 points)

The 12-lead ECG is a tracing of the electrical activity of the heart. The recording most often used for ECG analysis is the standard 12-lead ECG consists of 12 leads: two bipolar leads (one on each side) and ten limb leads. The large box method is used to calculate the heart rate from the QRS complex. The method uses a large box corresponding to 0.4 seconds in duration and then divides it into regular intervals of 0.1 seconds. This allows for easier heart rate calculation based on the QRS complex alone. The ECG shows ventricular depolarization, repolarization, action potential duration, conduction velocity, and QT interval. The regularity of an ECG is determined by calculating the R-R interval (RR interval). This can be calculated using either the small or large box method. The small box method counts R waves at 0.12 seconds each; if three or more are present in any lead, then that lead is considered regular. If two or fewer are present in any lead, then that lead is considered irregular. The large box method counts everything within two standard deviations of the mean R-R interval (noted as +/- SD) (Majorowicz et al., 2019).

Regularity:

- The patient’s heart rate was regular at 96 beats per minute.

- The large box method is used to determine heart rate using the electrocardiogram. This method involves calculating the distance between each beat by measuring the interval between two adjacent points on the tracing. The larger the interval between two adjacent points, the faster the heart rate is. By calculating how many millimeters apart two points are along an axis on an ECG tracing and then multiplying that by 100 (millimeters), we can calculate how fast your heart is beating at any given time.

- For example, if you see a small box next to 80 on an ECG tracing, your heart rate was 80 beats per minute or less (or 40 bpm). If you see a small box next to 160, your heart rate was 160 bpm or more (or 120 bpm) (Majorowicz et al., 2019).

ST-segment elevation: For the 12 lead ECG strip provided, identify leads showing ST-segment elevation and which areas of the heart are affected by ischemia. Be specific about the structures and locations involved. (15 points)

Lead I:

ST-segment elevation in leads I, II, V5-6. In the lead V2-3, the ST segment is elevated in the inferior wall of the left ventricle. In lead V4-6, there is ST-segment depression in the inferior wall of the left ventricle.

Lead II:

ST-segment elevation in leads II, III, aVF. There is ST-segment depression in VR and lead V2-3.

Lead III:

ST-segment elevation in leads III, aVR, V1-3. ST-segment depression in aVL and lead V4-6 (Ozaki et al., 2018).

Leads IV, aVL, V5-6:

There is ST-segment depression in leads IV and V5-6, with very subtle ST-segment elevation (most likely artifactual) noted at the apex of the heart. This may represent early degenerative changes associated with CAD or right ventricular hypertrophy (RVH).

T-wave inversion: T-wave inversion occurs when there is depolarization of one part of the heart but repolarization of another part (because of a change in conduction velocity). Stenocardium can be depolarized more than normal myocardium, causing repolarization further away from ST depression. This could cause ST-segment depression to appear earlier than it should if there were no change in conduction velocity.

PR segment hyper-acceleration: A similar pattern can be seen with PR segment hyper-acceleration, where there appears to be an early component that precedes the secondary baseline component by about 1.5 seconds.

Treatment of ACS/AMI: Describe the urgent treatment (pharmacologic, non-pharmacologic) the nurse should expect. (15 points)

 1. Pharmacologic treatment:

-Analgesics: acetaminophen (Tylenol) or ibuprofen (Advil, Motrin). Opioid analgesics should be avoided due to the risk of respiratory depression (Ozaki et al., 2018).

-Nitrates: nitroglycerin (Nitrostat) is also significant for application in clients experiencing chest pain and high blood pressure.

-Thrombolytics: agents such as tissue plasminogen activator (tPA), urokinase, and streptokinase may be used to dissolve clots that cause ACS/AMI (Majorowicz et al., 2019).

-Vasodilators (nitroglycerin) relax blood vessels by causing vasodilation and leading to improved perfusion of the heart muscle, which improves cardiac output and decreases afterload on the left ventricle and oxygen demand on the myocardium during exercise testing while reducing myocardial ischemia by decreasing afterload on the left ventricle during exercise testing.

-Antiplatelet agents such as aspirin and clopidogrel (Plavix) are used to prevent future heart attacks or strokes caused by blockage of blood vessels in the heart or brain (Simari, 2019).

2. Nonpharmacologic treatment:

-Treatment of ACS/AMI can be affected by underlying conditions such as atherosclerosis, coronary artery disease, or diabetes mellitus. Treating these conditions can help reduce the risk of future cardiovascular complications. Treatment for these conditions includes diet modifications, exercise programs, and medications that help improve cholesterol levels, blood pressure, and insulin resistance.

Complications of ACS/AMI: Describe potential complications the nurse should be aware of when caring for the patient. (15 points)

Ongoing pain, shock, hypoxia, and hyperglycemia are common complications after an ACS/AMI. Pain is considered a significant predictor of mortality in patients with ACS/AMI, and it is essential to assess pain control as rapidly as possible. This can be accomplished through early ambulation and reassurance regarding the patient’s condition. Analgesics such as acetaminophen or NSAIDs are appropriate for moderate to severe pain relief in this setting. Hyperglycemia has effectively lowered cardiac output, heart rate, and systolic blood pressure in patients with ACS/AMI. Therefore, monitoring for hypoglycemia or hyperglycemia is vital to prevent further cardiovascular damage and death from hypoperfusion syndrome. Hypoglycemia may occur due to inadequate insulin dose or excessive insulin dosage, while hyperglycemia can result from excessive insulin dose and inadequate respiratory effort (COPD) (Haider et al., 2020). In both cases, an increase in glucose administration is indicated until normalization occurs; then, therapy should be decreased gradually until symptoms resolve without rebound elevation in blood glucose levels.

Nursing education: Describe topics that should be included in nursing education to prepare the patient for discharge. (15 points)

The nursing care plan should be reviewed with the patient and family. This will include the discharge planning process and the following topics:

Patient teaching: The patient is taught about their condition and anticipated changes in self-care. This education should occur before discharge but can be done at any time during a hospital stay. Patients must understand what they need to do on their own after discharge, as they may no longer be under the care of a physician or nurse (Simari, 2019).

Discharge teaching: Patients are taught how to prepare for discharge, including performing home exercises, knowing where to call for help if needed, and getting medicines from home. They may also need other information about medications and dietary restrictions, such as alcohol or caffeine intake.

The nurse should teach the patient about their diet for the next 7-10 days. After that, they should be instructed to eat small meals three times per day; avoid eating late at night because it can increase coughing that can further aggravate an already irritated chest wall; drink plenty of fluids (at least eight 8 oz glasses per day); take their medications as prescribed by their physician, and rest as much as possible (Haider et al., 2020).

The nurse should instruct patients with GERD about when they need to see a specialist for more treatments and more frequent follow-up visits with their primary care physician or gastroenterologist.

Other topics

Disclosure of all medications, including OTC diets and over-the-counter (OTC) medications.

Discussions on how to manage self-care activities at home.

Include a discussion about smoking cessation programs available through community resources.

Scholarly writing (15 points)