Assessment of Cardiac Function Chapter 26 WEB

8/7/2019 Assessment of Cardiac Function Chapter 26 WEB

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Assessment of Cardiac

Function

Chapter 26


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Assessment of the Cardiovascular

SystemOn Your Own:

Review the anatomy of the heart and

vessels Review normal circulation

Review coronary circulation

Review conduction


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Coronary Circulation


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Mean Arterial Pressure

average pressure at which blood moves

through vasculature (B&S, p. 358

MAP = Systolic BP + 2(diastolic BP)

3


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Mean Arterial Pressure

The Mean Arterial Pressure (MAP) is 80 mm Hg.

What does this mean?

The MAP drops to 60 mm Hg. What are the

implications of this value?

The MAP drops to 55 mm Hg. What are theimplications of this value? What should be

administered to the patient?


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Conduction System of the Heart


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Impulse Conduction

The heart rate is 80 bpm. From where is this impulse

originating? What does this mean?

The heart rate is 50 bpm. From where is this impulseoriginating? Are there any other possibilities? What

does this mean? What could be the cause?

The heart rate is 30 bpm. From where is this impulseoriginating? What does this mean? What could be the

cause?


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Cardiac Hemodynamics

Key principle:

Blood flow, in part, is determined by the flow

of blood from an area of higher pressure to

one of lower pressure

In what chamber would you expect to have the

highest pressure?


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Cardiac Cycle

Diastole

2/3 of the cardiac cycle

Relaxation and filling of the atria and ventricles

Systole

1/3 of the cardiac cycle

Contraction and emptying of the atria and

ventricles


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Mechanical Properties

Cardiac output

What is it?

What is normal?

Why is it important?

Cardiac index

What is it?

What is normal?

Heart rate

What is it?

What is normal?

Stroke volume

What is it?

What is normal?

What factors influence

it?


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Variables that Influence Stroke

Volume

Preload

Degree of myocardial fiber stretch at the

end of diastole and just before contraction Determined by LVED pressure and blood

return from the venous system

Starlings Law: the more the heart fillsduring diastole, the more forcefully it

contracts


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Variables that Influence Stroke

VolumeAfterload

Pressure or resistance that the ventricles mustovercome to eject blood through the semilunarvalves and into the peripheral blood vessels.

Impedance (the peripheral component of afterload)

Pressure heart must overcome to open theaortic valve

Amount of impedance depends upon aorticcompliance and total systemic vascularresistance, a combination of blood viscosity andarteriolar constriction


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Critical Thinking Question

You have a inch and 1 inch diameter

garden hose. You are pumping the same

amount of water through each one.

Which one will have to pump against more

resistance?

Which one will have a lower pressure?

How does this analogy correlate to bloodvessels?


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Preload and Afterload


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Contractility

What is it?

What drug is often given to increase

contractility?

What increases contractility?

What decreases contractility?


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Vascular System

On Your Own

Review Purpose, Structure and Function

Physiology of blood pressure


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Blood Pressure

What is blood pressure?

What two factors are the primary determinants of bloodpressure?

How do increases or decreases in either or both of thesefactors affect blood pressure values?

What body systems are involved in the regulation ofblood pressure?

What external factors can affect blood pressure?


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Assessment: History

Patients will be queried regarding: History of cardiac

symptoms

Dyspnea

Fatigue

Paroxysmal nocturnal

dyspnea

Orthopnea Chest pain

palpatations

Syncope

Cough

Past health history

Medications

Risk factors

Age

Diet Activity

Smoking


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Additional Assessment Areas

Health perception and management

Nutrition and metabolism

Elimination

Activity and exercise

Sleep rest patterns

Cognition and perception

Self-perception and self-concept Roles and relationships

Sexuality and reproduction

Coping and stress tolerance


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Pack-years

Smoking history should be reported in pack

years:

Number of packs per day multiplied by thenumber of years has smoked

(0.5 pack X 10 years = 5 pack years)


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Physical Exam

Cyanosis

Petechiae

Edema

Pulses

Heart sounds

Murmurs

Bruits

Blood pressure

Neck vein distention

Skin color

Hair distribution on

extremities

Lesions

Clubbing

dysrhythmias


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Postural BP Changes

Compare and contrast normal

and abnormal blood pressure

responses to postural position

changes.

What do orthostatic changesindicate?


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Assessment of Clubbing

Schamroth Method

Place fingernails of the ring fingers

together and hold up to light If a diamond shape can be seen between

the nails findings are normal

Absence of the diamond shape indicatesclubbing


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Assessing for Clubbing


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Diagnostic Tests

Cardiac Biomarkers

Chemistries

CXR & Fluroscopy

ECG

Continuous Cardiac

Monitoring

Cardiac StressTesting

Echocardiography

Radionuclide imaging

Cardiac

catheterization

Angiography

Hemodynamic

monitoring


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Important Markers ofMyocardial

Damage

Creatine Kinase

specific to brain, myocardial, and skeletalmuscle cells

Presense in blood indicates tissuenecrosis or injury

Isoenzymes identify specific source

CK-MB activity is most specific forMI withpredictable rise over 3 days (peak at 24 hoursafter onset of chest pain)


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Early Markers

CK-MB antibody assay can detectmyocardial necrosis within 3 hours ofEDadmission

CK-MB subforms 1 and 2 (early andspecific indicators)

Myoglobin (early, sensitive, but non-

specific) Troponin T and I (early with wide

diagnostic time frame)


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Additional Labs

Blood Chemistries

Coagulation studies

Hematologic studies Lipid Profile

Cholesterol and Triglycerides

BNP CRP

Homocysteine


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Other Diagnostic Tests

ECG

Continuous electrocardiographic monitoring Hardwire vs. Telemetry

Signal averaged

Continuous Ambulatory ECG (HolterMonitor)

Echocardiography Traditional vs. Transesophageal

Cardiac Stress Testing Exercis, Pharmacologic, Mental

Radionuclide Imaging Myocardial Nuclear Perfusion Imaging

ERNA (aka MUGA) Computed Tomography (CT)

Positron Emission Tomography (PET)

Heart Catheterization /Angiography

Electrophysiologic Studies


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Cardiac Catheterization

Provides:

Visualization of coronary blood flow

Measurement of pressures in heart chambers

Determination of O2 saturation of the blood Visualization of the valves

Procedure:

One or more catheters inserted (femoral;brachial)

Dye injected

Takes about 1 hour


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Before the test:

ECG

Chest x-ray

Urine Blood

BUN/Creatinine

Fast 8-12 hours

IV started

Patient Education Length of procedure

May feel palpitationsand flushing

Basic Pre-oppreparation


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Indications:

Confirm suspected

disease

Determine locationand extent of disease

To assess stable

angina, uncontrolled

HF

To determine best

therapeutic options

To evaluate effects of

treatment

Complications

Rt: thrombophlebitis, PE,vagal response

Lt: MI, Stroke, arterialbleeding or thrombo-

embolism, dysrhythmias

Rt. or Lt.: cardiac

tamponade, hypovolemia,pulmonary edema,

hematoma, contrast

media reaction


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During the test:

May be asked to cough or deep breathe

After the test:

Firm pressure over site observe for bleeding,hematoma

Circulatory checks every 15 minutes for 1-2hours then every 1-2 hours after stable

Observe for dysrhythmias

Keep leg or arm straight for several hours

Increase fluids to flush out dye

Watch for orthostatic hypotension when first up


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Hemodynamic Monitoring

Invasive system used in critical care toprovide quantitative information aboutvascular capacity, blood volume, pump

effectiveness, and tissue perfusion. Directly measures pressures in heart and

great vessels

CV

P, PA,I

ntraarterial BP Provides more accurate measurements ofblood pressure, heart function and volumestatus


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Involves significant risks, informed consent

is required

Components Catheter with infusion system

Transducer

Monitor


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Central Venous Pressure (CVP)

Pressure in vena cave or right atrium Indirect measurement of right ventricular pressure

Normal 0-8 mm Hg

Elevated: hypervolemia, Heart failure

Low:

decreased preload related to hypovolemia

Complications Infection, Pneumothorax, Air embolism


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Pulmonary Artery Pressure

Normal: 25/9; mean 15 mm Hg

Measurement helpful: Assesses LV function

Assists in determining etiology of shock

Evaluates response to medical interventions

Capable of measuring: RA pressure

PA systolic pressure

PA diastolic pressure Mean pulmonary artery pressure (4.513 mm Hg)

Pulmonary artery wedge pressure


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Pulmonary Artery Pressure

Elevated PA wedge pressure:

LV failure; hypervolemia; regurgitation;

intracardiac shunt

Low PA wedge pressure:

Hypovolemia; afterload reduction

Complications:

Infection, PA rupture, Pulmonary thrombo-

embolism, Pulmonary infarction, Catheter

kink, Dyrhythmias, Air embolism


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Intrarterial BP Monitoring

Direct and continuous BP measurement

Provides access for ABG or blood

samples Must have collateral circulation

Allen test

Ultrasound Doppler study

Complications: Local obstruction, air embolism, pain and arterial

spasm, infection

Assessment of Cardiac Function Chapter 26 WEB

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