cardiacintro
TRANSCRIPT
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)