Anatomy & Physiology Review

Cardiovascular system

Heart

Pumps 1000 gallons of blood daily

Beats 100,000 times a day

Located in the mediastinum between the lungs

4 chambered pump Known as double pump

Tissue Layers

Epicardium—outer layer Myocardium—middle layer (bulk of heart,

muscle tissue) Endocardium—inner layer (thin, smooth,

epithelial cells) Pericardium=tough membrane surrounding

heart (double membrane) protects heart from injury d/t infection, trauma

Chambers

Atria=upper chambers act as reservoir Ventricles=lower chambers Right & Left side separated by septum Right atrium receives deoxygenated blood from

entire body Right ventricle receives deoxygenated blood from

right atrium & pumps blood to lungs via the pulmonary artery

Right side receives deoxygenated blood, pumps it to the lungs via pulmonary arteries

(gas exchange in alveoli)

Left side receives oxygenated blood from the lungs via pulmonary veins & pumps it throughout the body

Chambers

Left atrium receives oxygenated blood from the lungs via pulmonary veins

Left ventricle receives oxygenated blood from left atrium, & pumps blood through aorta to all parts of the body

Heart Valves

4 valves in the heart keep blood moving forward & prevent backflow

AV VALVES Tricuspid (3 flaps) located between right

atrium & right ventricle

Mitral (bicuspid) has 2 cusps & is located between left atrium & left ventricle

Chordae Tendineae

Small cordlike structures that connect the AV valves to the walls of the heart

Work with Papillary muscles to make tight seal & prevent backflow with ventricular contraction

Valves Con’t

Semilunar valves located where blood exits ventricles

Composed of 3 cusps that resemble half moon

Pulmonary semilunar valve located between right ventricle & pulmonary artery

Blood exits right ventricle & travels to the lung via pulmonary artery

Valves Con’t

Aortic semilunar valve located between left ventricle and aorta

When left ventricle contracts, blood is forced into aorta, and semilunar valve closes.

VESSELS

Arteries=carry blood FROM the heart

Veins=carry blood back TO the heart

Arterioles=smallest arteries

Venules=smallest veins

Capillaries=smallest vessels—connect arterioles & venules

Electrical Conduction System

SA node Located in posterior wall of Right Atrium Known as pacemaker of the heart Initiates impulses that cause contraction Produces impulses between 60-100 times/min Average of 72 beats/min Normal heartbeat called normal sinus rhythm

Conduction

Cardiac impulse spreads through atria over intra-nodal & intratrial pathways

When all cells in atria are excited, they contract in unison

Impulse then reaches AV node (atrio-ventricular ) which stimulates ventricles (like the atria were)

Conduction

Impulse then travels to bundle of HIS & R&L bundle branches

Then to Purkinje fibers….. Then ventricles contract

SA nodeAV nodebundle of HISR &L bundle branchesPurkinje fibers

Cardiac Cycle

Refers to a complete heartbeat

Atria contract while the ventricles relax

Contraction phase=systole (depolarization)

Relaxation phase=diastole (polarization)

Complete diastole & systole takes 0.8 sec

Cardiac Cycle

LUBB-DUBB= heart sounds

LUBB= heard when AV valves close

DUBB=heard when semilunar valves close

MURMER=swishing sound heard with ineffective closure of the valves

Cardiac Output

Defined as the amount of blood ejected from the left ventricle in 1 minute(Average norm=3.5-8.0 L/min) Can be increased 2 ways—By increasing heart rate, and increasing stroke volume

Stroke volume=amt of blood pumped per contraction

Stroke Volume × Heart Rate = CO

Ejection Fraction (EF) is a measure of ventricular efficiency Important indicator in heart failure

Normal EF=60%

Regulation

Nervous system can change the heart rate Medulla contains C V centers Sympathetic nerve impulses increase rate &

force of contractions Parasympathetic nerve impulses along vagus

nerve decrease heart rate

Electrolyte Balance

Necessary for cardiac function

Potassium & Calcium especially

↑ potassium decreases heart rate ↓potassium =disturbed rhythm ↑calcium causes increase & prolonged

contractions ↓ calcium = decreased heart function

Hormones and Heart (cont’d)

Aldosterone Regulates Sodium/Potassium

Atrial Natriuretic Peptide Hormone secreted by atria Increases excretion of Sodium

Hormones and Heart

Epinephrine

Increases: Heart Rate Force of Contraction Cardiac Output Systolic BP

VESSELS

Arteries=carry blood FROM the heart

Veins=carry blood back TO the heart

Arterioles=smallest arteries

Venules=smallest veins

Capillaries=smallest vessels—connect arterioles & venules

Blood Pressure

Force of Blood Against Blood Vessel Walls Measured in mm/Hg Normal

Systolic 90 to 135 mm Hg Diastolic 60 to 85 mm Hg

Pulse pressure=difference between systolic & diastolic

Blood Presure

Systolic—measures pressure during ventricular contraction (systole)

Affected by size of lumen of arteries, arterioles, (elasticity )

affected by athero & arterio sclerosis Under regulation by autonomic nervous

system (sympatheticvasoconstriction Diastolic– measures pressure during

ventricular relaxation (diastole)

Renin-angiotension mechanism

If blood flow through kidney decreases, so does renal filtration & urinary output

Decreased BP stimulates kidneys to secrete renin This sets off the angiotensin-aldosterone mechanism Renin splits the plasma protein angiotensinogen (made

in liver) to angiotensin I Angiotensin I is converted to angiotension II by an

enzyme found in lung tissue Angiotensin II causes vasoconstriction & stimulates the

adrenal cortex to secrete aldosterone Aldosterone increases reabsorption of sodium ions by

the kidneys…water follows sodium back to blood, increasing blood volume….and blood pressure

Coronary Circulation

Blood flows through heart muscle by way of two small vessels--Left & Right coronary arteries

If an artery becomes occluded, tiny branches provide collateral circulation.

If occlusion is severe, surgery may be needed.

Pathways of Circulation

Pulmonary Circulation—deoxygenated blood passes through R atrium to R ventricle, to pulmonary arteries to the lungs

Pulmonary Veins bring oxygenated blood to L atrium

Systemic Circulation---Blood is pumped from left ventricle of heart through Aorta, out to body and returns via the Vena Cava to the Right atrium

Hepatic Portal Circulation

Special part of the circulation –blood from capillaries in digestive tract & spleen flows through portal vein into capillaries in the liver before returning to heart

Allows liver to regulate blood levels of glucose, amino acids and iron & remove toxins (drugs, alcohol) from circulation

Aging and Cardiovascular system

Older Adult Changes in cardiac musclereduced cardiac

output Decreased tissue perfusion d/t decreased

cardiac output Sclerotic changes to vesselsdecreased

elasticity, hypertension Coronary artery changes lead to collateral

coronary circulation Polypharmacytoxicity

Nursing Assessments (Data Collection)

Health History (WHAT’S UP?”) Medications Family history Health promotion

Objective data VS Pulses Clubbing Homan’s Sign

Diagnostic Examinations

Fluroscopy

Angiogram

Aortogram

X-ray

CT, MRI

Cardiac Catheterization

Long catheter inserted into vein or artery of arm or leg

Used to visualize chambers, valves, vessels, and arteries, determine patency

Contrast dye is used Performed under sterile asepsis NI:

determine if sensitivity to iodine exists Pressure (sandbag) to insertion site to prevent

hemorrhage Monitor V/S, takes 1 1/2 – 3 hrs

Electrocardiography (EKG)

Record of electrical currents generated by the heart muscle. 12 leads placed on chest & limbs

EKG has 3 distinct waves—P,QRS,T P wave (occurs with spread of impulse from SA node

throughout atria PR interval= time it takes for impulse to reach

ventricles & START contracting

EKG

QRS complex= occurs during time necessary for the impulse to spread through bundle of HIS & Purkinje fibers and cause ventricles to contract

S-T segment=indicates beginning of ventricular recovery

T wave=complete recovery & relaxation of the ventricle

EKG (con’t)

Helps determine the nature of MI & interpret dysrhythmias

Not definitive dx of MI

NI: explain help patient undress, dress

wipe off paste

Ambulatory EKG

Holter monitor Small portable recorder attached to patient by

1-4 leads Records patterns & rhythms continuously for

24 hrs Used in conjunction with patient “log” or diary Note any chest pain, SOB Scanned for problems by Dr.

Cardiac Monitors

Visual display of the cardiac electrical activity of the heart

Can set alarms to warn of abnormal rate or rhythm

Can run a “strip” (EKG) of activity

Telemetry=transmission of data to a distant location such as the nurses station

Stress testing

Monitoring of the heart’s capability during exercise

Uses treadmill, stair climbing, etc Patient is monitored carefully, and coaxed to

a limit of exertion to evaluate ischemia (decreased oxygen to heart)

Can use Persantine or adenosine, injection instead of exercise

Stress test

Normal finding=no ST segment depression or arrythmia upon exercise

Based on theory that patients with CAD will have ST segment depression when exercising.

Abnormal Finding=>1mm ST depression NI: no smoking, caffeine, alcohol, 2-3 hrs prior. Eat

light meal Stop if patient becomes dyspneic, fatigued, chest

pain, > pulse, bp, or arrythmias

Echocardiogram

Ultrasound of the heart

Shows structures of the heart

Including valves

Non-invasive

Thallium Scan

Injection of Thallium 201 (ion) that is actively transported into normal cells.

If cell ischemic (without oxygen), thallium not picked up on image

“cold Spot” image is produced

Injected while patient exercises on a treadmill

PET Scan

Positron Emission Tomography=computerized xray technique using radioactive substance to examine the metabolic activity of body structures

Can distinguish between viable and non viable heart muscle to identify best candidates for bypass surgery

Lab studies

Blood Cultures to diagnose infective endocarditis Blood Chemistry

Cholesterol (desirable < 200mg/dl total) Mod risk-- 200-240 High risk240 LDL—60-160 (Desired <130) HDL—29-77 (desire > 60) 1/3 of Americans have levels <200

Triglycerides

10-190 (goes up with age) Most common reason for elevation=diabetes Instructions: Fast prior for 12 hrs Normal diet for 2 days prior No alcohol 24 hrs prior NI: avoid excess sugars & CHO

Serum Enzymes & Cardiac Markers

SGOT,AST=found in heart muscle & liver primarily

Increased in acute MI or liver damage Elevated in 6-10 hrs Peaks in 24-48 hrs Decreased in 4-6 days NI: no IM’s before test

Markers Con’t

CPK, CK MB=found in heart muscle Elevated in acute MI Elevated in 4-6 hrs Peaks in 12-24hrs Decreases in 3-4 days

Troponin I, Troponin T

Highly specific indicators of MI

Rises in 4-6 hrs

Remains elevated for 2 weeks

Hemodynamic Monitoring

To assess volume and pressure of blood within the heart & vascular system

Uses multi- or triple lumen catheters Inserted into a central artery or vein

Arterial Lines

Used to draw arterial blood samples, (ABG’s) and do continuous BP monitoring

Used in radial, brachial or femoral artery Catheter tip contains sensor that transmits fluid

pressure to a transducer which converts data to a visual waveform

Eliminates need for auscultating bp

CVP

Central Venous Pressure= Pressure in R atrium. Normal =4-10cm/H2O. Uses 3 way stop-cock, need to “zero” at levle of patient’s R atrium—Patient in supine position.

Used to detect excess or deficits in venous blood volume

Swan-Gans Catheter

Catheter with balloon at the tip used for measuring pulmonary arterial pressures, right atrial pressures, left atrial pressures and left ventricular end diastolic pressures

Pulmonary Artery Monitoring

Catheter (swan-gans) inserted into pulmonary artery

Measures pulmonary artery pressure & right atrial pressure, & CVP

Used to aid in early treatment of fluid imbalances & left sided congestive heart failure, Pulmonary Edema (↑ PAP)

Pulmonary Wedge Pressure

Tiny balloon on end of swan-gans inflated with tiny amt (0.8cc) fluid & “wedged” to obstruct flow of pulmonary artery blood for few seconds. Pressure is measured (norm =4mm/hg)

Increase PWP seen in ↓ cardiac output

Balloon must then be deflated immediately to prevent pulmonary infarction

Electrophysiology studies

Study of the electrical impulses which control the pumping action of the heart.

When the impulses “misfire” can cause arrhythmias

Electrodes placed in the heart to deliberately provoke arrhythmias in controlled environment

Cardiac Output

Cardiac output= amount of blood pumped out of the ventricle each min.

Average normal = 3.5-8.0L/min Can be increased in 2 ways

Increasing the heart rate Increasing the stroke volume (amt of blood

pumped per contraction (norm=65-70 ml)