NUR 120 (Unit 4) Cardiovascular Diagnostic Tests and Risk Factor Analysis 3.1 - 4.1

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57 terms · Mrs Gulledge Nur 120 CCTC Spring 2012

Why do we perform Dx tests?

- get baseline
- assess efficacy of tx
- dx conditions
- determine course of tx
- check to see if meds are therapeutic

Cardiac Biomarkers Analysis

- Creatinine kinase (CK)
- CK isoenzymes (CK-MB)
- Proteins (myglobin, troponin T, troponin I)

*drawn from venous blood*

*enzymes levels are tested in relationship to the time of onset of the chest discomfort and symptoms--can help tell time of damage*

Creatinine Kinase (CK)

- enzyme
- normal component of muscles
- is elevated when there is muscle damage

The Creatinine Kinase isoenzyme for Cardiac Muscle is:

CK-MB

What does CK-MB tell us?

- increases only when there has been damage to cardiac muscle cells.
- Elevated CK-MB assessed by mass assay is an indicator of acute MI (impaired tissue perfusion); the level begins to increase within a few hours and peaks within 24 hours of an MI. If the area is reperfused (eg, due to thrombolytic therapy or PCI), it peaks earlier.
- damaged cells release these enzymes into the blood stream

why are CK and CK-MB significant

- CK and ISO are the first to increase
- are the most reliable for MI's
- usually testable within a few hours after damage and peak within 24hrs

*if testing occurs too late after 24hrs, it wont be helpful--it will decline*

What proteins are useful to check for with cardiac patients?

- myoglobin
- troponin i
- troponin t

*drawn from venous blood*

Myoglobin is:

- a heme protein that helps transport oxygen.

Why is myoglobin testing significant?

- a protein that is found in cardiac and skeletal muscle.
- The myoglobin level starts to increase within 1 to 3 hours and peaks within 12 hours after the onset of symptoms.
- An increase in myoglobin is not very specific in indicating an acute cardiac event
- negative results are an excellent parameter for ruling out an acute MI.

Troponin i, t are:

- protein only found in cardiac muscle
- it can be detected within 3-4 hrs and remain elevated for 1-3 weeks
- it peak in 4-24 hrs
- since it elevates early, it allows for early dx of MI
- they are drawn in a series over time to see the trend of the levels over time

(LDH) lactic dehydrogenase:

- an enzyme that is released following tissue damage
- many muscle types have it
- not as reliable to measure myocardial damage

Blood Chemistries: Lipid Profile: Cholesterol

- normal is <200mg/dl

- LDL: bad: should be less than 130 for norm pt. pts with CAD or high risk, ldl should be below 70

- HDL: good: should be above 35

- should fast for 8 - 12 hrs before test
- increase in cholesterol correlates W/ increase risk of CAD
- gives indications for risk of CAD

*good cholesterol is stable and carries bad chol away from the arteries. bad chol sticks to artery walls and causes plaque build up*

Cholesterol: HDL and LDL (diagram)

** LDL - Lazy - lays around in arteries and creates plaque on wall
** HDL - Helpful - helps move LDL out of the arteries

LDL/HDL (memory)

Blood Chemistries: Lipid Profile: Triglycerides:

- Normal Range: 100-200
- these are important because they can help predict CAD

High Cholesterol is found in pts who are:

- of all ages
- not only elderly
- found in children

Serum Electrolytes

- Na
- Ca
- K
- Mg

Serum Electrolytes: Na

- normal range is 135 - 145 mEq/L
- cation
- less amt in cell/great amt in serum
- exchanges with K

hyper causes fluid volume excess & effects preload and effects output

Serum Electrolytes: Ca

8.6 - 10.2 mg/dl
- cation
- less amt in the cell/lrg amt in the serum
- exchanges with P
- effects blood coagulation, muscle contraction, neuromuscular activity

Serum Electrolytes: K

- normal range is 3.5 - 5.0 mEq/L
- large amounts in the cell/ small amts in serum
- exchanges with Na
- can alter neuromuscular activity and cause ventric fib and cardiac stand still (asystole)

Serum Electrolytes: Mg

- 1.8 - 2.7 mEq/L
- cation
- large amts in the cell/ less amts in the serum
- important for neuromusc activity, balances K stores, absorption of Ca

Brain Natriuretic Peptide (BNP)

- Synthesized in cardiac ventricles
- unique to cardiac system
- Diagnostic for CHF
- neurohormone related to the stress and stretch of the ventricles.. indicator of damage... relation to increased preload and increased ventriclular pressure. (ventricle gets filled and overextends the ventricles.. BNP is released)
- when levels of BNP are over 100 is suggestive of CHF (fluctuates quickly and widely) is indicitive of the state of ventricular filling at the time the blood is drawn

Blood Urea Nitrogen (BUN)

- normal is 10-20 mg/dL
- when elevated: reflects reduced renal perfusion secondary to decreased Cardiac Output
- increased BUN indicates intravascular volume deficit which relates to decreased preload and decreased stroke volume
- reflects hydration as well

Blood Coagulation Studies

- PTT
- PT
- INR

Blood Coag Studies: PTT:

- prothrombin time
- 30-35 secs is normal
- heparin prolongs this rate
- get baseline and then redraw every 12 hrs or so.

Blood Coag Studies: PT

- partial thromboplastin
- 9.5-12 seconds
- warfarin prolongs this rate
- get baseline and prob redrawn everyday

Blood Coag Studies: INR

- International Normalized Ratio
- therapeutic normal is 2.0 - 3.5

What CBC's are important to a cardiac patient:

RBC: carries O2
WBC: fights infxn
H&H: carries more O2 with better numbers of RBC
Platelets: helps with coagulation

Chest X-Ray

- Determine size, contour, position of heart, can be anterior posterior or lateral
- not significant radiation for pts
- HCP have to be cautious due to exposure

Fluoroscopy

- cardiac/vascular pulsation, unusual cardiac contours
- is kind of like a continuous xray - used for placing caths or pacemakers, etc

12 lead ECG or EKG

- looks at electrical impulses of the heart, takes 3 second snapshot of heart
- can be ordered serially
- ordered usu STAT
- our job is to make sure its ordered, done and report back to MD

ECG/EKG Cycle (diagram)

EKG P wave is:

-depolarization of the atria

EKG: Between the P and Q is:

delay in AV node

EKG: the QRS wave is

Depolarization of ventricles

EKG: the T wave is

repolarization of ventricles

Cardiac Electrophysiology (diagram)

echocardiogram

- an echocardiogram uses sound waves to image the heart. color doppler uses color to show blood flow
- can measure chambers, estimate ejection fraction
- the nurse is responsible for: teaching the pt about the procedure, painless but there is pressure, it takes 30-45 mins

TransEsophageal Echocardiography (TEE)

- an ECHO done through the esophagus
- better quality than standard ECG
- needs to be NPO before and consent form
- put to sleep, invasive, transducer inserted through esophagus and echos from the back of heart
- can see if there are mural thrombi (pooling leads to clot due to A fib within the heart)
- more uncomfortable than ECHO
- have IV inserted, drugs pushed
- moderate sedation - conscious sedation,
- anesthetized throat with spray,
- monitor BP during procedure

Nursing Responsibilites for TEE

- assess after, npo for hour after procedure, ice chips to soothe throat until gag reflex returns
- VS every 15mins and then every hour.

Mural Thrombi are contraindications to:

- cardioversion: converting A. Fib to sinus rhythm using shock stimulus

CT Scans are used for:

- help provide cross-sectional images of heart

PET Scans are used for:

- information about myocardial perfusion and viability

MRI Scans are used for:

- imaging of great vessels of the heart and heart
- be aware of metal
- claustrophobia

Holter monitoring

- skin electrodes
- hardwire connection to pouch
- no shower
- journal the day
- 24hrs

Transtelephonic monitoring

- usu for pacemaker to read results
- used to do check ups

Telemetry monitoring

- leads set up to little box and left with the pts
- pt can ambulate
- it only monitors rhythm-doesnt tell SOB and doesnt show chest pain - pts must tell nurse about them

Hardwire monitoring

- when pts are sick in the bed
- skin electrodes
- is hardwired to osciliscope/bedside monitor on the wall
- shows continuous cardiac rhythm

cardiac stress testing (exercise)

- tests for tolerance
- can be inpatient or outpatient
- trying to see how heart responds to stress on the heart r/t activity
- if you fail stress test you will prob get a cardiac catheter

pharmacologic stress testing

- trying to see how heart responds to stress on the heart r/t stress induced by meds
- if you fail stress test you will prob get a cardiac catheter

cardiac catheter

- invasive procedure wth arterial/venous catheter introduced or guided by fluoroscopy
- gives info about structure/fnx if chambers, valves, great vessels, extent of vessel blockage
- usually done in a cath lab
- usually done by cardiologist or surgeon

Patient Teaching for cardiac catheter

- fasting prior to prevent vomit and aspiration
- pt will be awake
- pt will be asked to cough and deep breath during procedure
- pt may feel palpitation
- local anesthetic agent to site
- may have IV sedation or PO
- bed rest post cath
- takes about 30-45 mins

Nursing Considerations for Cardiac Catheter

- monitor BP
- will usually be femoral or brachial artery
- typically uses iodine dye as contrast - check for pt allergy
- pt may be asked to change position
- right side cath is safer than the left side
- consent form will need to be signed
- pt could have cardiac arrest, stroke, clots, infxn at site, bleeding due to rupture, dysrhythmia due to touching the heart wall, cardiac perferations
- Labs prior to procedure: BUN/Cr, H&H, Platelet, BMP, PT/PTT
- nursing dx: risk for imparired tissue perfusion (leg or arm) check periph pulses

Post Cath Care Nursing Considerations

- Assessment: peripheral pulses, Color & temperature, Dysrhythmias

Non-modifieable Risk Factors for Cardiac Disease

- fam hx of CAD
- increasing age
- gender
- race

Modifiable Risk Factors for Cardiac Disease

- hyperlipidemia
- hypertension
- cig smoking
- elevated glucose levels
- obesity
- phys inactivity
- Type A personality-behavioral modification

Men vs Women and CAD

genetically men are more likely to have CAD but women are more likely to die from CAD due to having more acute and severe episodes

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