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Laboratory & Diagnostic procedures

NSG 409Spring 2014

Cardiac Laboratory Studies Hematological studies Coagulation studies Blood chemistries Electrolytes Serum lipid studies

Why hematological studies???? What coagulation studies ?????

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Cardiac Laboratory Studies Hematolgical studies:

Complete Blood count Blood is the transport medium for nutrients

such as oxygen and glucose, as well as electrolyte. Plasma, protein, and hormones.

Changes in blood cell integrity and total cell count may reflect specific disorders of the cardiac system and should be considered an integral part of the laboratory assessment

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Cardiac laboratory studies Coagulation Studies

Provides information about the patient`s ability to form, maintain, and dissolve blood clots.

Platelets count, prothrombin time (PT), Partial thromboplastin(PTT), Fibrinogen level and, activated clotting time.

Clients with AF, Endocarditis, after MI, or prosthetic valves tends to form thrombi

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Cardiac Laboratory Studies Electrolytes

K…important in the regulating of cardiac rate.

Na…maintain acid base balance and regulate fluid balance

CL…maintain acid base balance Carbon dioxide … Ca …Ionized calcium (free calcium) is

responsible for cardiac and neuromuscular excitability and blood coagulability.

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Cardiac Laboratory Studies Electrolytes

Mg…Alterations in normal magnesium levels are reflected in disruptions in neuromuscular activity, such as in the patient with arrhythmia

Glucose …reflect nutritive status of the cell.

Phosphorus…Abnormalities can be seen with alterations in heart rate, alterations in neuromuscular function, and reciprocal changes in serum calcium.

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Cardiac Laboratory Studies Serum Lipid Profile:

Cholesterol: Can accumulate in arterial walls. (recommended <200mg/dl; <160 if CAD exists)

HDL: . Higher levels of HDL are associated with decreased risk of coronary heart disease.

HDL >60mg/dl LDL: Higher levels of LDL are associated with a

higher risk for the development of cardiovascular disease.

LDL (60-70% of total cholesterol); <130 mg/dl Triglycerides: Levels greater than 200 mg/dL

can contribute to the development of atherosclerosis and coronary artery disease.

Why Cardiac enzyme

To determine whether you are having a heart attack or a threatened heart attack (unstable angina) if you have chest pain, shortness of breath, nausea, sweating, and abnormal electrocardiography

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Cardiac Enzymes

present in low amounts in the serum of healthy individuals.

when cells are injured, enzymes leak from damaged cells.

No single enzyme is specific to the cells of a single organ.

Cardiac enzymes are enzymes found in cardiac tissue.

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Cardiac Enzymes Three of the many enzymes present in cardiac

tissue have widespread use in the diagnosis of acute MI: creatine kinase (CK), lactate dehydrogenase (LDH), and aspartate aminotransferase (AST; previously termed serum glutamic oxaloacetic transaminase [SGOT]).

CK can be divided further into components called isoenzymes ( more specific for cardiac disease).

The routine sampling of serum for AST and LDH for the diagnosis of acute MI is no longer recommended.

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Creatine Kinase (Creatine phosphokinase): This enzyme is found in heart muscle (CK-MB), skeletal muscle (CK-MM), and brain (CK-BB). 

Total CPK (creatine phosphokinase)Normal: Men:55–170 international units per liter (IU/L) Women:30–135 IU/L.

Creatine kinase is increased in over 90% of myocardial infarctions. However, it can be increased in muscle trauma, physical exertion, postoperatively, convulsions.

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Cardiac enzymes Creatine Phosphokinase Isoenzymes Rises and returns to normal sooner than total CK

Rises in 4-6 hours Returns to normal in 2 days

peaks in 24-28 hoursSerial analysis of Ck Isoenzymes is the most

specific, sensitive, and cost effective In diagnosing MI.

Elevated in percarditis, myocarditis, trauma, and cardiac surgery.

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Cardiac enzymes Creatine Phosphokinase Isoforms This test is becoming more popular.

MB2 (tissue CK-MB) is released from heart muscle and converted in blood to MB1(plasma CK-MB). A level of MB2 equal or greater than 1.0 U/L and an MB2/MB1 ratio equal or greater than (1)1.5 indicates myocardial infarction.

Enzyme Studies

Creatinine kinase Found in heart muscle Rises 4 to 6 hours after MI; peak 18 to 24

hours Biochemical markers: myocardial

proteins Troponin-I and troponin-T

Enzyme Studies Neurohumoral hormones: brain-type

natriuretic peptide Evaluates heart failure

Newer diagnostic markers C-reactive protein and d-dimer

Lactic DehydrogenaseNo longer used for IHD

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comments

Cardiac enzyme levels must always be compared with symptoms, medical history, physical examination, and electrocardiography (EKG, ECG) results.

Troponin is an accurate method for quickly diagnosing heart attack, but because it takes up to 6 hours to rise, it can be low or negative at first.

Troponin is more specific to heart muscle and remains in the bloodstream longer than CPK.

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CPK-MB, which is found only in heart muscle, is a more specific way to estimate the amount of heart muscle damage than total CPK.

The total CPK enzyme level can be elevated from vigorous exercise, intramuscular injections, crush injuries to muscles, muscular dystrophy, or muscle inflammation.

Another enzyme, myoglobin, may be tested along with cardiac enzymes to diagnose a heart attack. 19

What Affects the Test

Other diseases, such as muscular dystrophy and certain autoimmune diseases.

Other heart conditions, such as myocarditis and some forms of cardiomyopathy.

Medicines, especially injections into muscles (IM injections).

Cholesterol-lowering medicines (statins). Heavy alcohol use. Recent strenuous exercise. Kidney failure. Recent surgery or serious injury.

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Brain natriuretic peptide (BNP)&  N-terminal prohormone of brain natriuretic peptide (NT-proBNP)

secreted by the ventricles of the heart in response to excessive stretching of heart muscle cells

a normal level rules out acute heart failure in the emergency setting

 typically increased in patients with left ventricular dysfunction, with or without symptoms

Normal: BNP <100 ng /ml

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Useful resources http://www.cardiosource.org/

Science-And-Quality/Practice-Guidelines-and-Quality-Standards.aspx American College of Cardiology.

http://www.nhlbi.nih.gov/about/ncep/ National Cholesterol Education Program

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Cardiac enzymes

Biochemical Markers: myocardial protiens Myocardial proteins specific for

detecting myocardial damage. Myoglobin Troponin

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Myoglobin: Is the O2 transporting pigment of

skeletal and cardiac muscle. Found in striated muscle. Damage to

skeletal or cardiac muscle releases myoglobin into circulation.

Time sequence after myocardial infarction Rises fast (1-2 hours) after myocardial

infarction Peaks at 2-4 (6 – 8) hours Returns to normal in 20 - 36 hours.

Very sensitive to reperfusion after thromobolytic therapy.

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Troponin These are contractile proteins of the myofibril.

The cardiac isoforms are very specific for cardiac injury and are not present in serum from healthy people.

Troponin complex is a heteromeric protein

playing an important role in the regulation of skeletal and cardiac muscle contraction.

It consists of three subunits, troponin I (TnI), troponin T (TnT) and troponin C (TnC); (TnC is available in smooth muscles)

TnT and TnI are presented in cardiac muscles in different forms than in skeletal muscles.

Only one tissue-specific isoform of TnI is described for cardiac muscle tissue (cTnI).

cTnI is expressed only in myocardium.

Troponin I (cTnI) or T (cTnT) are the forms frequently assessed. 

* Rises 2 - 6 hours after injury Peaks in 12 - 16 hours

cTnI stays elevated for 5-10 days, cTnT for 5-14 days

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r Diagnostic Markers

C-reactive protein are newer marker of systemic inflammation, has been shown to be elevated in patients with acute coronary syndromes.

Normal values are 0 to 2 mg/dL. Serum values greater than 3 mg/dL in patients with

acute coronary syndrome (ACS) or greater than 5 mg/dL in patients who are post–coronary interventional procedure may indicate a higher risk!!!

C –Reactive Protein

D dimer D dimer represents the end product of

thrombus formation and dissolution that occurs at the site of active plaques in acute coronary syndromes; this process precedes myocardial cell damage and release of protein contents.

D dimer, which is detected early and remains elevated for days, can identify unstable plaque in high-risk patients when troponin and CK-MB have not yet been released.

Universal normal serum values for D dimer 500 μg/L indicates increased sensitivity for acute MI.

(D-dimer values < or = 500 ug/L are normal)

Cardiac Diagnostic Studies

New and advanced diagnostic tests and tools are constantly being introduced to further understand the complexity of disease, injury, and congenital or acquired abnormalities.

Non Invasive Procedure:

ECG. Holter Monitor. Stress Test. Echocardiography. Chest X-ray Studies.

Electrocardiogram (ECG or EKG) Electrocardiogram: A test that records the electrical

activity of the heart, shows abnormal rhythms (arrhythmias or dysrhythmias), and detects heart muscle damage.

provide information about the Mechanical function and conduction of the heart – can not tell about structural or perfusion disorders.

Types Continuous MonitoringContinuous Monitoring ECG.

Standard/12-lead.Standard/12-lead.

Signal-Averaged (SAE)Signal-Averaged (SAE)زز

Continuous MonitoringContinuous Monitoring

provide continuous monitoring of cardiac activity in the cardiac unit.

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Continuous Monitoring

Standard/12-leadStandard/12-lead

Record electrical impulses as they travel through the heart.

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Standard-12-leadStandard-12-lead

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Electrocardiogram

Signal-Averaged Signal-Averaged (SAE)(SAE)

Signal-Averaged (SAE):Signal-Averaged (SAE): A test that is much like an ECG, but takes longer

because it records more information.

detect electrical impulse (late potential) occurs during diastole late into QRS complex and ST-segment that can’t be detected by normal ECG. Done at bed side to determine if pt is susceptible

for vent dysrhythmias.

Signal-Averaged Signal-Averaged (SAE)(SAE)

Signal-Averaged (SAE):Signal-Averaged (SAE): A test that is much like an ECG, but takes longer

because it records more information.

detect electrical impulse (late potential) occurs during diastole late into QRS complex and ST-segment that can’t be detected by normal ECG. Done at bed side to determine if pt is susceptible

for vent dysrhythmias.

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Single Average

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Holter Monitoring

A small, portable, battery-powered ECG machine worn by a patient to record heartbeats on tape over a period of 24 to 48 hours - during normal activities. At the end of the time period, the monitor is returned to the physician's office so the tape can be read and evaluated.

ECG tracing recorded continuously for a day or longer to detect arrhythmias that may not appear in a routine ECG but when the pt. At work or moving.

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Holter Monitoring

a small portable ECG size of a transistor radio. The monitor is carried with shoulder strap (battery pack).

The purpose is to obtain continuous or intermittent graphic tracing of the patient's pulse & ECG while performing daily activities. It is maintained for at least 24 hours. The patient keeps a log (diary) of activities R/T time of day

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There are 2 types of Holter monitoringThere are 2 types of Holter monitoring: A. continuous recording - the ECG is

recorded continuously during the entire testing period.

B. event monitor, or loop recording - the ECG is recorded only when the patient starts the recording, when symptoms are felt.

Holter monitoring may be done when arrhythmia is suspected but not seen on a resting or signal-average ECG, since arrhythmias may be transient in nature and not seen during the shorter recording times of the resting or signal-average ECG.

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Diagnostic Studies Exercise Electrocardiogram (Stress

Testing): measure body reaction to increased exercise level.

(changes in HR, RR, BP, perception is recorded) Identify client at risk and diagnosis Angina. It is indicated for:

symptoms of coronary artery disease determining functional capacity post MI evaluate exercise induced arrhythmias evaluate at risk individuals for coronary artery

disease evaluate pharmacological effect on angina

Advise the patient to avoid stimulants the day of the test (caffeine), to wear comfortable walking shoes. Some medications may be withheld prior to the test (Digoxin)

Test terminated when the heart rate (HR) reach the maximum or when ST depression greater than 3mm, fatigue, or chest pain.

Positive if the pt has chest pain, or hypotension, dysrhythmias before the predicted HR is achieved..

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Exercise Electrocardiogram (Stress Testing):

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Stress Testing Terminate test if chest pain or fatigue,

greatly increased HR, S/S MI or ischemia, drop in BP, sudden bradycardia, sever dyspnea, ST-segment depression >2-4 mm, loss of coordination, hypertension.

A positive exercise test is that test that has to be terminated before reaching the predicted maximum or submaximal limits.

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Diagnostic Studies Radionuclide testing/

Pharmacologic stress testing: Used in clients who are physically unable

to exercise (such as patients with Orthopedic problem, neuro problem).

Noninvasive injection of small amount of radioisotope (e.g. thallium ).

Evaluate myocardial perfusion and LV fnx.

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May be combined with pharmacologic stress testing for clients unable to exercise

Ischemic or injured cardiac muscles will not be able to take up the radioactive substance normally; the result will appear as a cold/dark spot indicating the area of injury that did not take up the radio active substance that was injected.

Vasodilators (Persantine & adenoside) drugs may be used to induce the same ischemic changes in the diseased heart, as in exercise-induced ischemia

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Echocardiography (ultrasound): A noninvasive test that uses sound waves

to produce a study of the motion of the heart's chambers and valves. The echo sound waves create an image on the monitor as an ultrasound transducer is passed over the heart.

Noninvasive evaluation of cardiac structure. No preparation necessary, painless. Patient Need to lie quietly 30 min to 1 hr.

Diagnostic Studies

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Diagnosis of cardiac tamponade at the bedside.

Provide information about cardiac structure, cardiac wall motion, ejection fraction (EF), ventricle volumes, and valves.

An echocardiogram can utilize one or more of four special types of echocardiography

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M-Mode echocardiographyM-Mode echocardiography :

This is the simplest type of echocardiography.

M-mode echo is useful for measuring heart structures, such as the heart's pumping chambers, the size of the heart itself, and the thickness of the heart walls.

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Doppler echocardiographyDoppler echocardiography :

This Doppler technique is used to measure and assess the flow of blood through the heart's chambers and valves.

Also, Doppler can detect abnormal blood flow within the heart, which can indicate a problem with one or more of the heart's four valves or with the heart's walls.

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Color Doppler:Color Doppler:

Color Doppler is an enhanced form of Doppler echocardiography. With color Doppler, different colors are used to designate the direction of blood flow.

This simplifies the interpretation of the Doppler technique.

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2-D (2-dimensional)echocardiography2-D (2-dimensional)echocardiography

This technique is used to "see" the actual structures and motion of the heart structures.

A 2-D echo view appears cone-shaped on the monitor, and the real-time motion of the heart's structures can be observed.

This enables the physician to see the various heart structures at work and evaluate them.

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Transesophageal Echocardiography (TEE):

Is done by inserting a probe down your throat (esophagus) to the level of the heart.

The TEE transducer works the same as the transducer used for the other procedures.

However, a clearer image can be obtained with a better quality than echo.

Useful in clients with thick lung tissues.

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Nursing Considerations for TEE procedure:

Pt should be NPO at least 6 hours before procedure You will undress pts from the waist up, and EKG pads

attached to pts chest & then givehim/her a gown to wear.

Tell your patient that he/she will lie on a table or bed for the procedure.

An intravenous (IV) line is placed in pts hand or arm, so that sedative medication can be given. Sedatives are given to help in relaxation, but your patient will remain awake enough to assist in the procedure by swallowing as the TEE probe is passed down throat.

A numbing medication will be sprayed in the back of pt throat to make passage of the TEE probe more comfortable.

• After procedure pt should be NPO until gag reflex has return

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Diagnostic Studies

Chest X-ray Studies: Show the size and position of the heart,

position of intracardial lines, …

Magnetic Resonance Imaging (MRI):

most expensive, provides best information on chamber size, wall motion, valve function, and large vessel blood flow quantification, wall thickness, and tissue characteristics

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Magnetic Resonance Imaging (MRI) cont’:

The patient is placed in a tube for 60-90 minutes (explain this to the patient so he/she will not be fearful), patient may be premedicated.

NPO for at least 4 hours before the procedure.

Contraindicated in patients who have implanted metal parts (pacemakers, wires, metal valves, pumps, …)

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Diagnostic Studies Electrophysiological Studies

Invasive method to record cardiac electrical activity

A catheter inserted through the femoral, basilic, or subclavian vein

The procedure is to reproduce any dysrhythmia so that its origin may be isolated

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Diagnostic procedures Cardiac Catheterization Cardiac catheterization with

coronary angiography is a diagnostic procedure done to evaluate certain types of heart disease.

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Diagnostic StudiesCardiac Catheterization: A catheter is

inserted into a large vein or artery in either the leg (groin) or the arm (anticubital) areas to evaluate the right and left sides of the heart. Blood samples are obtained to determine O2 content in the various heart chambers. Insertion of a catheter into the heart and

surrounding tissue Diagnostic information on the structure,

performance, valves, and circulatory system

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Diagnostic procedures

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•Catheterization Procedure:

•Local anesthesia.

• Inserting an introducer-sheath.

• Inserting a catheter.

• Advancing the catheter.

Cardiac Catheterization

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Cardiac Catheterization performs to provide information about:

a. Blockages of the arteries.b. Function of the valves. c. Pressures. d. Pumping ability

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Diagnostic Studies

Cardiac Catheterization: Right-Sided catheterization:

Femoral or brachial vein (Rt-sided) to Rt atrium, ventricle then wedged in small PA (pulmonary artery)

Left-Sided Catheterization: Femoral or brachial artery, to the aorta then

Lt. ventricle

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Diagnostic ProceduresAngiography:

IV injection of contrast material into the heart during catheterization. Immediately, then x-rays taken to visualize any abnormalities in the cardiac circulation.

Coronary angiography shows the following: How many coronary arteries are blocked

Where are they blocked The degree of each blockage

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Diagnostic Procedures

Catheterization: (Pre-Procedure care):

Food and fluid are restricted 6 to 8 hours before the test.

health care provider should explain the procedure and its risks.

A witnessed, signed consent for the procedure is required.

Allergic history: to seafood, if the pt had a bad reaction to contrast material in the past

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Diagnostic Procedures

Catheterization: post coronary care:

assess pulses & B/P. assess amplitude of pulses on extremities used

force fluids - unless worried about fluid volume overload to facilitate elimination of contrast media

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Diagnostic Procedures Catheterization:

post coronary care:

Pressure dressing over arterial site (usually groin) & complete bed rest for up to 12 hrs & check site for bleeding.

Possible complications; Ventricular fibrillation, tachycardia, CVA, hypotension from contrast media that has diuretic effect

Instruct client to avoid bending the hips during the first 12-24 hours.