14.12:
Imaging Studies for Cardiovascular System V: CT
Cardiac computed tomography (CT) scanning is an advanced cardiac imaging technique that utilizes CT technology, with or without intravenous (IV) contrast, to produce accurate cross-sectional virtual slices of specific areas of the heart, coronary circulation, and major blood vessels such as the aorta, pulmonary veins, and arteries. The computer processes these slices to generate three-dimensional images. Multidetector CT (MDCT) is a rapid form of CT scanning that captures multiple slices simultaneously, producing high-resolution, clear images of cardiac structures.
Indications
Cardiac CT is used for various purposes, including assessing the presence, extent, and severity of plaque buildup and narrowing in the coronary arteries, detecting congenital cardiac anomalies, identifying and characterizing cardiac masses such as tumors, evaluating conditions affecting the pericardium, providing detailed anatomical information before cardiac surgery, and assessing the success of interventions like stent placements or bypass grafts.
Types
There are different types of Cardiac CT, each suited for specific diagnostic needs. Coronary CT angiography requires an IV contrast agent to enhance the X-rays and improve visualization of cardiac structures. This test evaluates the coronary arteries for stenosis, the aorta for aneurysms or dissections, graft patency after coronary artery bypass grafting, and pulmonary veins in individuals with atrial fibrillation. Calcium Scoring CT measures the amount of calcium in the coronary arteries to evaluate the risk of coronary artery disease (CAD).
Patient Preparation and Procedure
Preparation involves instructing the patient to avoid nicotine and caffeine for at least 24 hours before the scan, as these substances can affect heart rate. Beta-blockers may be administered to control heart rate and rhythm, thereby minimizing motion artifacts. Patients should be informed to hold their breath periodically during the scan to reduce artifacts. Renal function, particularly serum creatinine levels, must be assessed in patients with renal insufficiency. IV hydration should be provided before and after the scan to mitigate the effects of the contrast agent on renal function; for patients with a history of allergic response to contrast agents, premedication with corticosteroids and antihistamines is recommended.
During the procedure, position the patient supine on the CT exam table. Place the electrodes on the patient’s chest to monitor heart rate and enable ECG gating, synchronizing the scan with the cardiac cycle. Administer intravenous contrast to enhance the visibility of the heart and blood vessels, if required. The exam table then slides into the CT scanner, which takes multiple X-ray images from different angles. A computer processes the captured images to create detailed cross-sectional views of the heart and vessels.
After the procedure, patients are monitored briefly for any delayed allergic reactions to the contrast dye. They are encouraged to hydrate well to help eliminate the contrast material from their bodies. Patients can typically resume routine activities shortly after the procedure.
Nursing Interventions
Nursing interventions are critical for ensuring the procedure’s success and patient safety. Pre-procedure care includes educating the patient about the procedure and verifying their medical history, particularly regarding allergies and renal function. Patients should be informed about potential sensations during the contrast infusion, such as transient flushing, metallic taste, nausea, or bradycardia. During the procedure, nurses assist in positioning the patient, monitoring vital signs and comfort levels, and being prepared to manage any immediate reactions to the contrast dye. Post-procedure care involves monitoring for delayed allergic reactions to the contrast dye, encouraging hydration to help eliminate the contrast material from the body, providing post-procedure instructions, and ensuring the patient understands when to seek medical attention.
Cardiac computed tomography, or CT scanning, is an imaging technique that uses computed tomography technology, with or without contrast, to produce detailed cross-sectional images of the heart, coronary circulation, and major blood vessels.
This method assesses coronary artery disease, pre-surgical anatomy, congenital anomalies, and pericardial diseases.
Next, patient preparation includes explaining the procedure, assessing medical history for allergies, and evaluating renal function, such as serum creatinine in patients with renal insufficiency if contrast is used.
Before the CT scan, beta-blockers are administered to control heart rate.
During the procedure, the patient is positioned supine on a CT exam table. Electrodes are attached to the patient’s chest, and contrast material is injected if necessary.
The patient is instructedto hold their breath periodically during the scan to reduce artifacts.
The exam table then slides into the CT scanner, which takes multiple X-ray images from different angles.
Post-procedure care involves monitoring for delayed allergic reactions to the contrast material and encouraging the patient to stay hydrated.
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