CARDIOVASCULAR AND
CIRCULATORY FUNCTION
Overview of Anatomy and Physiology
Three layers: endocardium,
myocardium, epicardium
Four chambers: Right atrium
and ventricle, left atrium and
ventricle
Atrioventricular valves:
tricuspid and mitral
 Semilunar valves:
aortic and pulmonic
 Coronary arteries
 Cardiac conduction
system
(electrophysiology)
 Cardio hemodynamics
Anatomy of the Heart
Greater Vessels, Heart Chambers and Pressures
Cardiac Conduction System: Electrophysiology
Cardiac Conduction
 Two types of electrical cells in the heart
– nodal cells and Purkinje cells
o Nodal cells are the “pacemakers” of
the heart that initiate impulses
o Purkinje cells transmit impulses
across the heart
Cardiac Conduction
 Properties of electrical cells
o Automaticity – can initiate an impulse
o Excitability - response to a stimulus.
Pacemaker cells do not need a stimulus.
o Conductivity – Can transmit impulses from
one cell to another
Cardiac Action Potential
 Depolarization: electrical activation of cell
caused by influx of sodium into cell while
potassium exits cell
 Repolarization: return of cell to resting state
caused by reentry of potassium into cell
while sodium exits
Cardiac Action Potential
 Refractory periods
o Effective refractory period: phase in
which cells are incapable of depolarizing
o Relative refractory period: phase in
which cells require stronger-than-normal
stimulus to depolarize
Cardiac Action Potential Cycle
Cardiac Cycle
 Refers to the events that occur in the heart
from the beginning of one heartbeat to the next
 Number of cycles depends on heart rate
 Each cycle has three major sequential events:
o Diastole
o Atrial systole
o Ventricular systole
Cardiac Output #1
 Ejection fraction: percent of end diastolic
volume ejected with each heart beat (left
ventricle)
 Cardiac output (CO): amount of blood
pumped by ventricle in liters per minute
 CO = SV × HR
CARDIAC OUTPUT #2
 Stroke volume(SV): amount of blood ejected
with each heartbeat
o Preload: degree of stretch of cardiac muscle
fibers at end of diastole
o Afterload: resistance to ejection of blood from
ventricle
o Contractility: ability of cardiac muscle to
shorten in response to electrical impulse
Influencing Factors
 Control of heart rate
o Autonomic nervous system, baroreceptors
 Control of stroke volume
o Preload: Frank–Starling Law
o Afterload: affected by systemic vascular
resistance, pulmonary vascular resistance
Contractility
Contractility increased by catecholamines,
SNS, certain medications
Increased contractility results in increased
stroke volume
Decreased by hypoxemia, acidosis, certain
medications
Cardiovascular Assessment
Health history/personal habits
Demographic information
Family/genetic history
Cultural/social factors
 Risk factors
o Modifiable/Non-modifiable
Cardiovascular Assessment
 Health history
 Common symptoms
o Chest pain/discomfort
o Pain/discomfort in other areas of the upper body
o SOB/dyspnea
o Peripheral edema, wt gain, abd distention
o Palpitations
o Unusual fatigue, dizziness, syncope, change in LOC
Past Health, Family, and Social History
 Medications
 Nutrition/Elimination
 Activity, exercise/Sleep, rest
 Self-perception/self-concept
 Roles and relationships
 Coping and stress
Cardiovascular Physical Assessment
 General appearance
 Skin and extremities
 Pulse pressure/blood pressure; orthostatic changes
 Arterial pulse
 Jugular venous pulsations
 Heart inspection, palpation, auscultation
 Assessment of other systems
Cardiovascular Physical Assessment
 Blood pressure
o MAP
o Pulse Pressure
o Postural Blood Pressure Changes
Physiologic Changes with Aging
 Heart: Left ventricular hypertrophy, increase in
systolic blood pressure, valvular degeneration
 Arteries: Degenerative changes in vessel walls
affecting blood flow
Physiologic Changes with Aging
 Conduction system: Prolonged atrioventricular
(AV) conduction, rate and rhythm disturbances
 Exercise and cardiovascular response:
Decreased rate response with increased cardiac
workload
Heart Sounds
 S1 and S2
 S3 and S4
 Gallop sounds
 Snaps and clicks
 Murmurs
 Friction Rub
Laboratory Tests
 Cardiac biomarkers
 Blood chemistry, hematology, coagulation
 Lipid profile
 Brain (B-type) natriuretic peptide
 C-reactive protein
 Homocysteine
Refer to Table 25-4
Electrocardiography
 12-lead ECG
 Continuous monitoring
o Hardwire
o Telemetry
o Lead systems
o Ambulatory monitoring
Cardiac Stress Testing
Exercise stress test
o Pt walks on treadmill with intensity
progressing according to protocols
o ECG, V/S, symptoms monitored
o Terminated when target HR is achieved
Pharmacologic stress testing
o Vasodilating agents given to mimic exercise
Indications for Stress Test
Diagnostic Tests
 Radionuclide imaging:
o Myocardial perfusion imaging
o Positron emission tomography
o Test of ventricular function, wall motion
o Computed tomography
o Magnetic resonance angiography
Echocardiography
 Noninvasive ultrasound test that is used to:
o Measure the ejection fraction
o Examine the size, shape, and motion of
cardiac structures
 Transthoracic
 Transesophageal
Conditions Detected or Evaluated by
Echocardiography
Cardiac Catheterization
 Invasive procedure used to diagnose structural and
functional diseases of the heart and great vessels
 Right Heart Cath
o Pulmonary artery pressure and oxygen saturations
may be obtained; biopsy of myocardial tissue may
be obtained
 Left Heart Cath
o Involves use of contrast agent
Indications for Cardiac Catheterization
Electrophysiological Studies
 Diagnosis and treatment of serious dysrhythmias
 Venous catheterization of heart
 Induce dysrhythmias
Nursing Interventions-Cardiac Cath
 Observe cath site for bleeding, hematoma
 Assess peripheral pulses
 Evaluate temp, color, and cap refill of affected extremity
 Screen for dysrhythmias
 Maintain bed rest 2 to 6 hours
 Instruct patient to report chest pain, bleeding
 Monitor for contrast-induced nephropathy
 Ensure patient safety
Hemodynamic Monitoring
 Central venous pressure
 Pulmonary artery pressure
 Intra-arterial B/P monitoring
 Minimally invasive cardiac output monitoring devices
Phlebostatic Axis
Pulmonary Artery Catheter & Pressure
Monitoring System
Cardiac Function Measurements
 Cardiac index (CI) : means of assessing
tissue perfusion relevant to body size
 CI = CO (liter/min)/body surface area (m2)
 CO = stroke volume (SV) × heart rate (HR)
 SV = EDV – ESV-blood ejected by the
Left ventricle into the aorta per beat
 End Diastolic Volume (EDV) is the
amount of blood remaining in the L
Ventricle at the end of each filling cycle
(Diastole)
 End Systolic Volume (ESV) is the
amount of residual blood that is in the
Ventricle at the end of Systole
Ejection Fraction
 Ejection Fraction is the amount of blood
ejected during systole
 Ejection Fraction should be 2/3 of EDV
 Ejection Fraction may be measured noninvasively on Echocardiogram
 Normal is 60%
 40% or under is considered Congestive Heart
Failure