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Lecture Two: Laboratory and Diagnostic Examinations

Objectives of the Lecture

  • List diagnostic tests used to evaluate cardiovascular function.

  • Specify patient teaching with each exam test and lab value.

  • Apply knowledge of related nursing procedures and psychomotor skills when caring for clients undergoing diagnostic testing.

  • Assess the client for unexpected adverse responses to the therapy.

Introduction to Cardiovascular Diagnostic Testing

  • Focus on the understanding of diagnostic tests and lab draws related to the cardiovascular system.

  • Importance of educating patients and families about tests and their implications.

  • Enhances patient adherence and trust in the nursing process.

  • Enables nurses to advocate effectively for patients in discussions with medical teams.

Diagnostic Imaging Discussed

Chest X-Ray

  • Definition: A two-dimensional image produced using small amounts of ionizing radiation.

  • Purpose and Information Provided:

    • Records shape, size, and position of the heart.

    • Provides shadow outlines that indicate cardiomegaly or larger vessels like the aorta.

    • Detects aneurysms in large vessels and verifies placements of medical devices (pacemakers, defibrillators, central lines).

  • Patient Preparation:

    • Remove clothing and jewelry (wire in bras, necklaces).

    • Gown required in hospital settings.

    • Notify provider if patient is pregnant.

Coronary Artery Calcium Score (Coronary Calcium Scan)

  • Definition: A specialized multi-detector or multi-slice CT scan visualizing plaque deposits in heart arteries.

  • Importance: Identifies atherosclerotic plaques made of fat, cholesterol, and calcium.

  • Preparation for Test:

    • Avoid caffeine, stimulants, and smoking for 4 hours prior.

    • No jewelry.

    • Procedure lasts 10 to 15 minutes; ECG monitoring required.

  • Results Interpretation:

    • Score indicates risk for cardiovascular disease (0 - none; 300+ - severe).

Fluoroscopy

  • Definition: A real-time X-ray exam that produces motion pictures of internal structures, particularly the heart.

  • Uses: Helps detect coronary artery disease risks through IV contrast addition for better visualization.

  • Preparation:

    • Obtain consent due to the invasive nature of the test.

    • Assess kidney function (creatinine, BUN) as contrast is eliminated via kidneys.

    • Check for patient allergies to contrast material.

  • Post-care:

    • Assess insertion site for bleeding and maintain circulation checks (pedal pulses, wrist pulses).

    • Vitals taken frequently post-procedure (every 15 minutes initially).

Cardiac Catheterization (Heart Cath)

  • Definition: An invasive procedure visualizing heart chambers, valves, great vessels, and coronary arteries.

  • Uses: Diagnostic and treatment measures for cardiac disease; allows evaluation of critically ill patients.

  • Patient Teaching:

    • Educate on procedure steps; ensure patient understands and gives consent.

    • Discuss the need for multiple IV access points, one for fluids, one for medications.

    • Explain sensations (warm feeling during contrast injection).

  • Post-Procedure Care:

    • Monitor vital signs closely, check for site bleeding or hematoma development.

    • TR band usage for radial artery access; assess for complications.

Electrocardiogram (ECG/EKG)

  • Definition: A graphical representation of the electrical activity of the myocardium.

  • Components:

    • P wave: depolarization of the atria (squeeze).

    • QRS complex: depolarization of the ventricles (squeeze).

    • T wave: repolarization of the ventricles.

  • Procedure: Quick, requiring patient to lay still; takes a few minutes to set up.

  • Uses: Detects rhythm abnormalities quickly in emergency situations.

Continuous Cardiac Monitoring

  • Purpose: Assess the ongoing cardiac electrical activity in patients at risk for dysrhythmias.

  • Types: Holter monitors for at-home monitoring and institutional telemetry.

  • Nursing Responsibilities: Monitor alarms, check patient response to alarms, ensure electrode integrity.

Cardiac Stress Tests

Types of Stress Tests

  1. Exercise Stress Test

    • Monitors patient’s heart under physical stress (walking/running).

    • Preparation: NPO for 3 hours, wear comfortable clothing; IV access necessary for emergencies.

  2. Pharmacological Stress Test

    • For patients unable to exercise; uses medications to simulate exercise-induced heart stress.

    • Monitoring of vitals and ECG continuously.

    • Preparation/Nursing care: Same as exercise test, including NPO status.

  3. Nuclear Cardiac Stress Test

    • Involves radioactive dye to identify ischemic tissues.

    • EKG and vitals monitored continuously; prep involves NPO status and avoidance of stimulants.

Echocardiogram

  • Definition: An ultrasound examining the heart's structures.

  • Details Gathered: Size, shape, fluid on heart, ventricular function, cardiac output.

  • Ejection Fraction Importance: Indicates percentage of blood ejected from the left ventricle with each heartbeat:

    • Normal: 55% or above.

    • Moderate: 40% - 55%.

    • Less than 40% necessitates heart failure discussion.

PET Scan

  • Definition: A radiographic technique using a radioactive substance to observe heart structures and metabolic changes at the cellular level.

  • Preparation: NPO status, check blood sugar (should not exceed 200), wear gowns.

Laboratory Tests for Cardiovascular Evaluation

Types of Blood Tests

  1. Blood Cultures: Detect infections; must be obtained via venipuncture (not from ports).

  2. Complete Blood Count (CBC): Assess red and white blood cell counts.

  3. Coagulation Studies: Monitor anticoagulant therapy (PT/INR for Coumadin; PTT for heparin).

  4. Serum Electrolytes: Critical for myocardial function; monitor sodium, potassium, calcium, magnesium levels.

  5. Cardiac Enzymes:

    • Creatine Kinase (CK) and CK-MB: Indicate muscle damage; CK-MB is cardiac-specific.

    • Troponin T and I: Indicators of myocardial injury; sensitive markers for heart attacks.

  6. Lipid Profile: Assesses cardiovascular risk through cholesterol levels.

  7. Brain Natriuretic Peptide (BNP): Indicates heart failure.

  8. Homocysteine Levels: Elevated levels indicate risk for various vascular diseases.

  9. C-Reactive Protein (CRP): Indicates inflammation related to cardiovascular disease.

Summary and Conclusion

  • The lecture aims to consolidate knowledge of diagnostic tools for assessing cardiovascular health, emphasizing the nursing role in patient education, preparation and post-care monitoring.

  • Importance of understanding each test's implications for patient care and effective communication with medical teams.