Cardiac Stress Testing PDF

1/9/24, 12:52 AM herzing.realizeithome.com/RealizeitApp/Student.aspx?Token=lqf9HhURQ5RqpgqAkzH2zbusjeLUzRyumZIEGwikvZDA89aMIS3TVE3sojJO… Cardiac Stress Testing Normally, the coronary arteries dilate to four times their usual diameter in response to increased metabolic demands for oxygen and nutrie...

1/9/24, 12:52 AM herzing.realizeithome.com/RealizeitApp/Student.aspx?Token=lqf9HhURQ5RqpgqAkzH2zbusjeLUzRyumZIEGwikvZDA89aMIS3TVE3sojJO… Cardiac Stress Testing Normally, the coronary arteries dilate to four times their usual diameter in response to increased metabolic demands for oxygen and nutrients. However, coronary arteries affected by atherosclerosis dilate less, compromising blood flow to the myocardium and causing ischemia. Therefore, abnormalities in cardiovascular function are more likely to be detected during times of increased oxygen demand, or “stress.” The cardiac stress test procedures—the exercise stress test, pharmacologic stress test, and radionucleotide imaging studies—are noninvasive ways to evaluate if there is myocardial ischemia and higher myocardial oxygen requirement during these tests. Cardiac imaging is performed during the resting state and immediately after stress testing. The results can identify specific coronary artery lesions and ischemic areas of the heart (King, 2017). Since complications of stress testing can be life-threatening (MI, cardiac arrest, HF, and bradycardia and tachycardia with hemodynamic compromise), testing facilities must have staff and equipment ready to provide treatment, including advanced cardiac life support. Exercise Stress Testing Procedure During an exercise stress test, the patient walks or runs on a treadmill (most common) or pedals a stationary bicycle. A protocol guides exercise intensity based upon the patient’s age and heart rate goal (King, 2017). During the test, the following are monitored: two or more ECG leads for heart rate, rhythm, and ischemic changes; BP; skin temperature; physical appearance; perceived exertion; and symptoms, including chest pain, dyspnea, dizziness, leg cramping, and fatigue. The test is stopped when the target heart rate is achieved or if the patient experiences signs of myocardial ischemia. Abnormal findings include chest pain, ventricular arrhythmia, ST-segment depression, and lack of heart rate or BP elevation with exercise (King, 2017). Nursing Interventions In preparation for the exercise stress test, the patient is instructed to fast for several hours before the test and to avoid stimulants such as tobacco and caffeine. Medications may be taken with sips of water. The primary provider may instruct the patient to hold beta-blockers, calcium channel blockers, and digitalis for up to 48 hours before the stress test. Clothes and sneakers or rubber-soled shoes suitable for exercising are to be worn. The nurse prepares the patient for the stress test by describing how the stress test is performed, the type of monitoring equipment used, the rationale for insertion of an IV catheter, and what symptoms to report. The exercise https://herzing.realizeithome.com/RealizeitApp/Student.aspx?Token=lqf9HhURQ5RqpgqAkzH2zbusjeLUzRyumZIEGwikvZDA89aMIS3TVE3sojJO9aojXmGqF3… 1/10 1/9/24, 12:52 AM herzing.realizeithome.com/RealizeitApp/Student.aspx?Token=lqf9HhURQ5RqpgqAkzH2zbusjeLUzRyumZIEGwikvZDA89aMIS3TVE3sojJO… method is reviewed, and patients are asked to put forth their best exercise effort. If the test is to be performed with echocardiography or radionuclide imaging (described in the next section), this information is reviewed as well. After the test, the patient is monitored for 10 to 15 minutes until vital signs and assessment findings return to normal. Once stable, patients may resume their usual activities. Pharmacologic Stress Testing Procedure Patients who are cognitively impaired and unable to follow directions or physically disabled or deconditioned will not be able to achieve their target heart rate by exercising on a treadmill or bicycle. Vasodilating agents such as dipyridamole, adenosine, or regadenoson given as an IV infusion are used to mimic the effects of exercise by maximally dilating normal coronary arteries and identifying stenotic arteries that cannot vasodilate. The side effects of these agents are related to the vasodilating action and include chest pain, headache, flushing, nausea, heart block, and dyspnea. If necessary the effects of these drugs can be reversed with IV aminophylline. Adenosine has an extremely short half-life (less than 10 seconds), so any severe effects subside rapidly. These vasodilating medications are the agents used in conjunction with radionuclide imaging techniques. Patients undergoing pharmacologic stress tests must avoid xanthine derivatives including theophylline, aminophylline, and caffeine as they block the effects of the vasodilating agents. Dobutamine is another option for use during a pharmacologic stress test. This medication is a synthetic sympathomimetic agent that increases heart rate, myocardial contractility, and BP, thereby increasing the metabolic demands of the heart. It is the agent of choice when echocardiography is used because of its effects on altering myocardial wall motion (due to enhanced contractility). Dobutamine is also used for patients who have bronchospasm or pulmonary disease and cannot tolerate having doses of theophylline withheld. Nursing Interventions In preparation for the pharmacologic stress test, the patient is instructed not to eat or drink anything for at least 3 hours before the test. The patient must also be told to refrain from eating any liquid or food that contain chocolate or caffeine for 24 hours and to avoid taking medications that contain caffeine. This restriction also includes caffeinefree coffee, tea, and carbonated beverages. If caffeine is ingested before a stress test using vasodilating agents, the test will have to be rescheduled. Patients taking aminophylline, theophylline, or dipyridamole are instructed to stop taking these https://herzing.realizeithome.com/RealizeitApp/Student.aspx?Token=lqf9HhURQ5RqpgqAkzH2zbusjeLUzRyumZIEGwikvZDA89aMIS3TVE3sojJO9aojXmGqF3… 2/10 1/9/24, 12:52 AM herzing.realizeithome.com/RealizeitApp/Student.aspx?Token=lqf9HhURQ5RqpgqAkzH2zbusjeLUzRyumZIEGwikvZDA89aMIS3TVE3sojJO… medications for 24 to 48 hours before the test (if tolerated). The patient is informed about the transient sensations that may occur during infusion of the vasodilating agent, such as flushing or nausea, which will disappear quickly. The patient is instructed to report the occurrence of any other symptoms during the test to the cardiologist or nurse. The stress test may take about 1 hour, or up to 3 hours if imaging is performed. Radionuclide Imaging Radionuclide imaging studies are noninvasive tests that use radioisotopes to evaluate coronary artery perfusion, detect myocardial ischemia and infarction, and/or assess left ventricular function. Radioisotopes are unstable atoms that give off small amounts of energy in the form of gamma rays as they decay. When radioisotopes are injected into the bloodstream, the energy emitted can be detected by a gamma scintillation camera positioned over the body. These radioisotopes are called tracers. Myocardial Perfusion Imaging Myocardial perfusion imaging is performed using two types of techniques: single photon emission computed tomography (SPECT) or positron emission tomography (PET). It is commonly performed after an acute MI to determine if arterial perfusion to the heart is compromised during activity and to evaluate the extent of myocardial damage. It is also used to evaluate if myocardial ischemia from CAD is the cause of chest pain or other CAD-related symptoms. These imaging techniques are performed in combination with stress testing to compare images obtained when the heart is resting to images of the heart in a stressed state resulting from exercise or medications. An area of the myocardium that shows no perfusion or reduced perfusion is said to have a “defect” present. Comparing resting images with images taken after the stress test helps differentiate ischemic myocardium from infarct-related myocardium. A defect that does not change in size before and after stress is called a fixed defect. Fixed defects indicate that there is no perfusion in that area of the myocardium, which is the case after an MI. Defects that appear or that get larger after the stress test images are taken indicate reduced perfusion to that area of the heart. Because the defect disappears with rest, it is called a reversible defect. Reversible defects constitute positive stress test findings. Typically, cardiac https://herzing.realizeithome.com/RealizeitApp/Student.aspx?Token=lqf9HhURQ5RqpgqAkzH2zbusjeLUzRyumZIEGwikvZDA89aMIS3TVE3sojJO9aojXmGqF3… 3/10 1/9/24, 12:52 AM herzing.realizeithome.com/RealizeitApp/Student.aspx?Token=lqf9HhURQ5RqpgqAkzH2zbusjeLUzRyumZIEGwikvZDA89aMIS3TVE3sojJO… catheterization is recommended after a positive test result to determine the severity of obstructions to blood flow caused by CAD. The patient undergoing myocardial perfusion imaging with stress testing should be prepared for the type of stressor to be used (exercise or medication) and provided with details of what to expect during imaging. The imaging is performed in two stages. Usually, the resting images are taken first. An IV is inserted to administer the radioisotope, and electrodes are placed on the chest to monitor the heart rate and rhythm. Women who are nursing, pregnant or think they are pregnant should not undergo myocardial perfusion imaging. The nurse alerts the primary provider if any of these conditions are present. Single Photon Emission Computed Tomography (SPECT) SPECT is widely available and is the most common technique of myocardial perfusion imaging. In addition, the ability of SPECT to detect myocardial ischemia is between 80% and 90% (King, 2017). Procedure SPECT is a painless, noninvasive procedure that involves the injection of the nuclear medicine radionucleotide (technetium-99m [99mTc]; rubidium-82) and imaging. During SPECT, patients are positioned supine on the table with their arms over their heads. The gamma camera circles around the chest area converting the signals from the traces into pictures of the heart. The procedure takes approximately 30 minutes. The second scan is repeated after an exercise or pharmacologic stress test. Nursing Interventions The nurse’s primary role is to prepare the patient for SPECT and insert an IV catheter or assess an existing IV for patency and suitability. The IV is used to inject the tracer. The patient may be concerned about receiving a radioactive substance and needs to be reassured that these tracers are safe—the radiation exposure is similar to that of other diagnostic x-ray studies. No postprocedure radiation precautions are necessary. Positron Emission Tomography (PET) PET is another noninvasive procedure in which a radioactive tracer chemical is administered to the patient and images are obtained. These images generally have a higher resolution compared to SPECT. PET technology is expensive and is likely to be found at large or academic medical centers. https://herzing.realizeithome.com/RealizeitApp/Student.aspx?Token=lqf9HhURQ5RqpgqAkzH2zbusjeLUzRyumZIEGwikvZDA89aMIS3TVE3sojJO9aojXmGqF3… 4/10 1/9/24, 12:52 AM herzing.realizeithome.com/RealizeitApp/Student.aspx?Token=lqf9HhURQ5RqpgqAkzH2zbusjeLUzRyumZIEGwikvZDA89aMIS3TVE3sojJO… Procedure During PET, tracers are given by injection; one compound is used to determine blood flow in the myocardium, and another determines the metabolic function. The PET camera provides detailed three-dimensional images of the distributed compounds. The viability of the myocardium is determined by comparing the extent of glucose metabolism in the myocardium to the degree of blood flow. For example, ischemic but viable tissue will show decreased blood flow and elevated metabolism. For a patient with this finding, revascularization through surgery or angioplasty will probably be indicated to improve heart function. Restrictions of food intake before the test vary among institutions, but because PET evaluates glucose metabolism, the patient’s blood glucose level should be within the normal range before testing. Nursing Interventions The nurse instructs the patient to refrain from using alcohol and caffeine for 24 hours before undergoing PET because of the stimulating effects they may have on the heart. For patients with diabetes and who are taking insulin, the nurse needs to discuss insulin doses and food restrictions with the primary provider. The nurse assesses patients for fear of closed spaces or claustrophobia. Patients who have this condition are reassured that medications can be given to help them relax. The nurse also reassures patients that radiation exposure is at safe and acceptable levels, similar to those of other diagnostic x-ray studies. To prepare the patient for PET, the nurse inserts an IV or assesses the existing IV catheter for patency and suitability, and then describes the procedure to the patient. The patient is positioned on a table with hands above the head. The table then slides into a donut-shaped scanner. While in the scanner, the patient must lie still so that clear images of the heart can be obtained. A baseline scan is performed, which takes about 30 minutes. Then a tracer is injected into the IV and the scan is repeated. The patient’s glucose level is monitored throughout the procedure. The scan takes from 1 to 3 hours to complete. Echocardiography https://herzing.realizeithome.com/RealizeitApp/Student.aspx?Token=lqf9HhURQ5RqpgqAkzH2zbusjeLUzRyumZIEGwikvZDA89aMIS3TVE3sojJO9aojXmGqF3… 5/10 1/9/24, 12:52 AM herzing.realizeithome.com/RealizeitApp/Student.aspx?Token=lqf9HhURQ5RqpgqAkzH2zbusjeLUzRyumZIEGwikvZDA89aMIS3TVE3sojJO… Echocardiography is a noninvasive ultrasound test that is used to measure the ejection fraction and examine the size, shape, and motion of cardiac structures. It is particularly useful for diagnosing pericardial effusions; determining chamber size and the etiology of heart murmurs; evaluating the function of heart valves, including prosthetic heart valves; and evaluating ventricular wall motion. Transthoracic Echocardiography Procedure Echocardiography involves transmission of high-frequency sound waves into the heart through the chest wall and the recording of the return signals. With the traditional transthoracic approach, the ultrasound is generated by a handheld transducer applied to the front of the chest. The transducer picks up the echoes and converts them to electrical impulses that are recorded and displayed on a monitor. It creates sophisticated, spatially correct images of the heart. An ECG is recorded simultaneously to assist in interpretation of the echocardiogram. With the use of Doppler techniques, an echocardiogram can also show the direction and velocity of the blood flow through the heart. These techniques are used to assess for “leaking valves,” conditions referred to as valvular regurgitation, and will also detect abnormal blood flow between the septum of the left and right heart. Echocardiography may be performed with an exercise or pharmacologic stress test. Images are obtained at rest and then immediately after the target heart rate is reached. Myocardial ischemia from decreased perfusion during stress causes abnormalities in ventricular wall motion and is easily detected by echocardiography. A stress test using echocardiography is considered positive if abnormalities in ventricular wall motion are detected during stress but not during rest. These findings are highly suggestive of CAD and require further evaluation, such as a cardiac catheterization. Nursing Interventions Before transthoracic echocardiography, the nurse informs the patient about the test, explaining that it is painless. Echocardiographic monitoring is performed while a transducer that emits sound waves is moved over the surface of the chest wall. Gel applied to the skin helps transmit the sound waves. Periodically, the patient is asked to turn onto the left side or hold a breath. The test takes about 30 to 45 minutes. If the patient is to undergo an exercise or pharmacologic stress test with echocardiography, information on stress testing is also reviewed with the patient. https://herzing.realizeithome.com/RealizeitApp/Student.aspx?Token=lqf9HhURQ5RqpgqAkzH2zbusjeLUzRyumZIEGwikvZDA89aMIS3TVE3sojJO9aojXmGqF3… 6/10 1/9/24, 12:52 AM herzing.realizeithome.com/RealizeitApp/Student.aspx?Token=lqf9HhURQ5RqpgqAkzH2zbusjeLUzRyumZIEGwikvZDA89aMIS3TVE3sojJO… Transesophageal Echocardiography Procedure A significant limitation of transthoracic echocardiography is the poor quality of the images produced. Ultrasound loses its clarity as it passes through tissue, lung, and bone. An alternative technique involves threading a small transducer through the mouth and into the esophagus. This technique, called transesophageal echocardiography (TEE), provides clearer images because ultrasound waves pass through less tissue. A topical anesthetic agent and sedation are used during TEE because of the discomfort associated with the positioning of the transducer in the esophagus (refer to Chapter 15 for further discussion of sedation for procedures). Once the patient is comfortable, the transducer is inserted into the mouth and the patient is asked to swallow several times until it is positioned in the esophagus. The high-quality imaging obtained during TEE makes this technique an important firstline diagnostic tool for evaluating patients with many types of CVD, including HF, valvular heart disease, arrhythmias, and many other conditions that place the patient at risk for atrial or ventricular thrombi. Pharmacologic stress testing using dobutamine and TEE can also be performed. It is frequently used during cardiac surgery to continuously monitor the response of the heart to the surgical procedure (e.g., valve replacement or coronary artery bypass). Complications are uncommon during TEE; however, if they do occur, they are serious. These complications are caused by sedation and impaired swallowing resulting from the topical anesthesia (respiratory depression and aspiration) and by insertion and manipulation of the transducer into the esophagus and stomach (vasovagal response or esophageal perforation). The patient must be assessed before TEE for a history of dysphagia or radiation therapy to the chest, which increases the likelihood of complications. Nursing Interventions Prior to the test, the nurse provides preprocedure education and ensures that the patient has a clear understanding of what the test entails and why it is being performed, instructs the patient not to eat or drink anything for 6 hours prior to the study, and checks to make sure that informed consent has been obtained. The nurse also inserts an IV line or assesses an existing IV for patency and suitability and asks the patient to remove full or partial dentures. During the test, the nurse provides emotional support and monitors level of consciousness, BP, ECG, respiration, and oxygen saturation (SpO2). During the recovery period, the patient must maintain bed rest with the head of the bed elevated to 45 degrees. Following the procedural sedation policy of the agency, https://herzing.realizeithome.com/RealizeitApp/Student.aspx?Token=lqf9HhURQ5RqpgqAkzH2zbusjeLUzRyumZIEGwikvZDA89aMIS3TVE3sojJO9aojXmGqF3… 7/10 1/9/24, 12:52 AM herzing.realizeithome.com/RealizeitApp/Student.aspx?Token=lqf9HhURQ5RqpgqAkzH2zbusjeLUzRyumZIEGwikvZDA89aMIS3TVE3sojJO… the nurse monitors the patient for dyspnea and assesses vital signs, SpO2, level of consciousness, and gag reflex as recommended. Food and oral fluids are withheld until the patient is fully alert and the effects of the topical anesthetic agent are reversed, usually 2 hours after the procedure; if the gag reflex is intact, the nurse begins feeding with sips of water, then advances to the preprocedure diet. Patients are informed that a sore throat may be present for the next 24 hours; they are instructed to report the presence of a persistent sore throat, shortness of breath, or difficulty swallowing to the medical staff. If the procedure is performed in an outpatient setting, a family member or friend must be available to transport the patient home from the test site. Summary Continuous cardiac monitoring is an important tool in the clinical assessment of patients with a variety of conditions. It allows the detection of changes in heart rate, rhythm and conduction and is essential in detecting of life-threatening arrhythmias. This is achieved using a cardiac monitor, connected to a cable lead and skin electrodes, which captures the electrical activity predominantly through a single view (commonly lead II). The monitor function includes: A display of heart rate and rhythm Sound alarms above or below pre-set limits The provision of rhythm strips to document evidence of arrhythmia Alarms should never be ignored or turned off. Patients who may require cardiac monitoring include those who are hemodynamically compromised and/or at clinical risk of adverse events, such as patients with the following: Chest pain Palpitations https://herzing.realizeithome.com/RealizeitApp/Student.aspx?Token=lqf9HhURQ5RqpgqAkzH2zbusjeLUzRyumZIEGwikvZDA89aMIS3TVE3sojJO9aojXmGqF3… 8/10 1/9/24, 12:52 AM herzing.realizeithome.com/RealizeitApp/Student.aspx?Token=lqf9HhURQ5RqpgqAkzH2zbusjeLUzRyumZIEGwikvZDA89aMIS3TVE3sojJO… Acute Coronary Syndrome – STEMI, NSTEMI, unstable angina Following major surgery – ITU, HDU, cardiac surgery Major trauma Post cardiac/respiratory arrest Acute medical conditions – Pulmonary embolus, drug overdose, electrolyte imbalance Unexplained syncope episodes Shock Undergoing a specific treatment Review Telemetry (mobile cardiac monitor) or the central cardiac monitor are observation tools that allow continuous ECG, RR, and SpO2 monitoring. The patient group requiring telemetry are children diagnosed with a known/unknown arrhythmia, children at risk of arrhythmia, or children anticipated to be at risk of sudden cardiac deterioration. Telemetry is not a replacement for patient visualization and assessment. Cardiac monitoring accuracy relies on skin preparation, electrode and lead placement, equipment maintenance, patient monitoring, and education. Studies have shown that with appropriate education to the patient and family, patient safety is improved and anxiety associated with monitoring is reduced. Nurses who can identify ECG abnormalities are in a prime position to prompt immediate action and lessen patient complications. Aim https://herzing.realizeithome.com/RealizeitApp/Student.aspx?Token=lqf9HhURQ5RqpgqAkzH2zbusjeLUzRyumZIEGwikvZDA89aMIS3TVE3sojJO9aojXmGqF3… 9/10 1/9/24, 12:52 AM herzing.realizeithome.com/RealizeitApp/Student.aspx?Token=lqf9HhURQ5RqpgqAkzH2zbusjeLUzRyumZIEGwikvZDA89aMIS3TVE3sojJO… To guide safe and competent nursing and medical practice associated with the use of cardiac monitoring. Definition of terms Telemetry – A portable device that continuously monitors patient ECG, respiratory rate, and/or oxygen saturations while automatically transmitting information to a central monitor. ECG – Electrocardiogram is a diagnostic tool that measures and records the electrical activity of the heart via electrodes placed on the skin. Electrode – The patch that is placed onto the patient and attaches to the lead wire. Lead Wire - The lead that connects the electrodes to the telemetry unit. Arrhythmia – A rhythm in which the heart beats in an irregular or abnormal way. External Pacing – Temporary means of pacing a patient’s heart. This can occur through transcutaneous pacing or external wires coming from the atrium/ventricle. Collapse – For the purpose of this guideline, collapse refers to circulatory/hemodynamic collapse. Assessment Patients should be assessed daily for the appropriateness of cardiac telemetry. Acutely unwell patients at risk of life-threatening arrhythmias should be on strict bed rest and continuously monitored on the bedside monitor and close to emergency equipment. The AUM will be involved in all aspects of care, from patient assessment to daily reviews for appropriateness of telemetry. Patients aged 2 years and less are not recommended for telemetry. The size of the electrodes are generally too big for patients this age, and this can cause incorrect readings and problems with skin integrity. Prior to commencing telemetry monitoring, a baseline 12 or 15 lead ECG should be taken as per the cardiac team. Additional ECG’s should be performed if the ECG changes from patient baseline A patient on telemetry should be visualized hourly. With every ECG alarm, the patient should be visualized and assessed. It is the responsibility of nursing staff to know the where-abouts of their patient at all times. Toilet doors should not be locked; however, laminated signs may be used on doors instead Accurate lead placement and good skin preparation will reduce false readings. Skin that is clean and dry will allow better adherence of electrodes and a more accurate ECG. Daily assessment of skin is important in preventing skin excoriation and/or pressure area injury at the site of electrodes. https://herzing.realizeithome.com/RealizeitApp/Student.aspx?Token=lqf9HhURQ5RqpgqAkzH2zbusjeLUzRyumZIEGwikvZDA89aMIS3TVE3sojJO9aojXmGqF… 10/10