NEW Med Surg Exam 1 Review Chapter 25:
Introducing the Cardiovascular System 2022
Anatomy and physiology of the cardiovascular system
● Three layers: endocardium, myocardium, epicardium
● Four chambers: the right atrium, right ventricle, left atrium, left
ventricle
● Atrioventricular valves: tricuspid and mitral
● Semilunar valves: aortic and pulmonic
● Coronary arteries
● Cardiac conduction system (electrophysiology)
● Cardiac hemodynamics
● Notes:
○ “Myo” always means muscle
○ The left ventricle is thicker and larger than the other
chambers of the heart
Structures and functions of the cardiovascular system
● The heart
○ Four chambers
○ Composed of 3 layers:
■ Endocardium
■ Myocardium
■ Epicardium
○ Pericardium
○ The left ventricle wall is 2-3 times thicker than the right
● Notes:
○ “Chordae” are attached to the muscles of the heart
which makes it open and close
○ Inferior vena cava gets blood from the lower part of the body
○ Superior- head/brain
○ Percentage of blood ejected from the heart = ejection fraction
○ SA node is the natural pacemaker of the heart, it has an
inherent rate which means that is what is expected to
happen (60-100 bpm)
○ AV node is the secondary pacemaker, the rate is 40-60
bpm (backup system)
○ Ventricular pacemaker comes from small areas at the
bottom of the heart, the rate is 20-40 bpm
Electrocardiogram
● EKG is a graphic representation of the electrical part of the heart
● The straight line is called the isoelectric line (neutral line)
● P wave prints out with the firing of the SA node (it should be
rounded and peaked)
NEW Med Surg Exam 1 Review Chapter 25:
Introducing the Cardiovascular System 2022
,NEW Med Surg Exam 1 Review Chapter 25:
Introducing the Cardiovascular System 2022
● QRS: slight downward deflection before it rises up to the
R, follows the P wave, depolarization of the AV node from the
ventricle
● T wave represents depolarization
● Amplitude and height of the spikes
● Make sure it is complete, even, regular, what is the rate, are
there any interferences
The cardiac cycle
● Events that occur in the heart from the beginning of one heartbeat to
the next
● The number of cycles depends on the heart rate
● Each cycle has 3 major sequential events:
○ Diastole
○ Atrial systole
○ Ventricular systole
Cardiac Action Potential
● Depolarization
● Repolarization
● Refractory periods:
○ Effective refractory period
○ Relative refractory period
● Systole: contraction of myocardium
● Diastole: relaxation of myocardium
● Stroke volume
● Notes:
○ Systole: blood is being pushed out from the ventricles
○ Diastole: muscle is relaxing and filling
○ Stroke volume: the amount of blood ejected from the
ventricles with each heart rate
● Cardiac output: amount of blood pumped by each
ventricle in 1 minute (normal is 4-8L/min)
● CO = SV x HR
● Cardiac index: CO divided by body surface area (normal is 2.8-4.2
L/min/m2)
● Ejection fraction: % of end diastolic volume ejected
from the left ventricle with each heartbeat
● Notes:
○ Low ejection fraction means too much blood is left in the
ventricles
○ Echocardiogram records ejection fraction
Factors affecting cardiac output
● Preload:
○ Volume of blood in the ventricles at the end of diastole
NEW Med Surg Exam 1 Review Chapter 25:
Introducing the Cardiovascular System 2022
,NEW Med Surg Exam 1 Review Chapter 25:
Introducing the Cardiovascular System 2022
● Contractility
● Afterload:
○ Peripheral resistance against which the left ventricle must
pump
NEW Med Surg Exam 1 Review Chapter 25:
Introducing the Cardiovascular System 2022
, NEW Med Surg Exam 1 Review Chapter 25:
Introducing the Cardiovascular System 2022
Practice question
● A patient is receiving a drug that decreases afterload. To
evaluate the patient’s response to this drug, what is most
important for the nurse to assess?
○ A. Heart rate
○ B. lung sounds
○ C. blood pressure
○ D. jugular venous distention
Influencing factors (control of heart rate)
● Autonomic nervous system, baroreceptors, chemoreceptors
● Control of stroke volume
● Contractility increased by catecholamines, SNS, certain medications
● Increased contractility results in increased stroke volume
● Decreased by hypoxemia, acidosis, certain medications
● Preload: Frank-Starling Law
● Afterload: affected by systemic vascular resistance,
pulmonary vascular resistance
● Notes:
○ Catecholamines: hormones secreted by the adrenal
glands (put out adrenaline, cortisol, hormones that can
raise BP)
○ Medications that increase contractility (make the heart
beat faster): epinephrine, atropine, suphedrine, albuterol,
cocaine
○ Hypoxic: heart beats faster to try to get to the cells faster
Cardiovascular Assessment
● Health history
● Demographic information
● family/genetic history
● cultural/social factors
● Risk factors:
○ Modifiable
○ Non-modifiable
● Notes:
○ HPI: history of present illness (what brought
you to the hospital?) not what happened 10
years ago
○ Medical history: past surgeries (to find out if they have a
stent or pacemaker, or problems with anesthesia), what
medications they are on, any supplements, how long have
they had a disease (hypertension, diabetes, hyperthyroid)
○ Demographic information: where they live, lifestyle, what
the patient has access to (patient just had heart surgery,
NEW Med Surg Exam 1 Review Chapter 25:
Introducing the Cardiovascular System 2022
Introducing the Cardiovascular System 2022
Anatomy and physiology of the cardiovascular system
● Three layers: endocardium, myocardium, epicardium
● Four chambers: the right atrium, right ventricle, left atrium, left
ventricle
● Atrioventricular valves: tricuspid and mitral
● Semilunar valves: aortic and pulmonic
● Coronary arteries
● Cardiac conduction system (electrophysiology)
● Cardiac hemodynamics
● Notes:
○ “Myo” always means muscle
○ The left ventricle is thicker and larger than the other
chambers of the heart
Structures and functions of the cardiovascular system
● The heart
○ Four chambers
○ Composed of 3 layers:
■ Endocardium
■ Myocardium
■ Epicardium
○ Pericardium
○ The left ventricle wall is 2-3 times thicker than the right
● Notes:
○ “Chordae” are attached to the muscles of the heart
which makes it open and close
○ Inferior vena cava gets blood from the lower part of the body
○ Superior- head/brain
○ Percentage of blood ejected from the heart = ejection fraction
○ SA node is the natural pacemaker of the heart, it has an
inherent rate which means that is what is expected to
happen (60-100 bpm)
○ AV node is the secondary pacemaker, the rate is 40-60
bpm (backup system)
○ Ventricular pacemaker comes from small areas at the
bottom of the heart, the rate is 20-40 bpm
Electrocardiogram
● EKG is a graphic representation of the electrical part of the heart
● The straight line is called the isoelectric line (neutral line)
● P wave prints out with the firing of the SA node (it should be
rounded and peaked)
NEW Med Surg Exam 1 Review Chapter 25:
Introducing the Cardiovascular System 2022
,NEW Med Surg Exam 1 Review Chapter 25:
Introducing the Cardiovascular System 2022
● QRS: slight downward deflection before it rises up to the
R, follows the P wave, depolarization of the AV node from the
ventricle
● T wave represents depolarization
● Amplitude and height of the spikes
● Make sure it is complete, even, regular, what is the rate, are
there any interferences
The cardiac cycle
● Events that occur in the heart from the beginning of one heartbeat to
the next
● The number of cycles depends on the heart rate
● Each cycle has 3 major sequential events:
○ Diastole
○ Atrial systole
○ Ventricular systole
Cardiac Action Potential
● Depolarization
● Repolarization
● Refractory periods:
○ Effective refractory period
○ Relative refractory period
● Systole: contraction of myocardium
● Diastole: relaxation of myocardium
● Stroke volume
● Notes:
○ Systole: blood is being pushed out from the ventricles
○ Diastole: muscle is relaxing and filling
○ Stroke volume: the amount of blood ejected from the
ventricles with each heart rate
● Cardiac output: amount of blood pumped by each
ventricle in 1 minute (normal is 4-8L/min)
● CO = SV x HR
● Cardiac index: CO divided by body surface area (normal is 2.8-4.2
L/min/m2)
● Ejection fraction: % of end diastolic volume ejected
from the left ventricle with each heartbeat
● Notes:
○ Low ejection fraction means too much blood is left in the
ventricles
○ Echocardiogram records ejection fraction
Factors affecting cardiac output
● Preload:
○ Volume of blood in the ventricles at the end of diastole
NEW Med Surg Exam 1 Review Chapter 25:
Introducing the Cardiovascular System 2022
,NEW Med Surg Exam 1 Review Chapter 25:
Introducing the Cardiovascular System 2022
● Contractility
● Afterload:
○ Peripheral resistance against which the left ventricle must
pump
NEW Med Surg Exam 1 Review Chapter 25:
Introducing the Cardiovascular System 2022
, NEW Med Surg Exam 1 Review Chapter 25:
Introducing the Cardiovascular System 2022
Practice question
● A patient is receiving a drug that decreases afterload. To
evaluate the patient’s response to this drug, what is most
important for the nurse to assess?
○ A. Heart rate
○ B. lung sounds
○ C. blood pressure
○ D. jugular venous distention
Influencing factors (control of heart rate)
● Autonomic nervous system, baroreceptors, chemoreceptors
● Control of stroke volume
● Contractility increased by catecholamines, SNS, certain medications
● Increased contractility results in increased stroke volume
● Decreased by hypoxemia, acidosis, certain medications
● Preload: Frank-Starling Law
● Afterload: affected by systemic vascular resistance,
pulmonary vascular resistance
● Notes:
○ Catecholamines: hormones secreted by the adrenal
glands (put out adrenaline, cortisol, hormones that can
raise BP)
○ Medications that increase contractility (make the heart
beat faster): epinephrine, atropine, suphedrine, albuterol,
cocaine
○ Hypoxic: heart beats faster to try to get to the cells faster
Cardiovascular Assessment
● Health history
● Demographic information
● family/genetic history
● cultural/social factors
● Risk factors:
○ Modifiable
○ Non-modifiable
● Notes:
○ HPI: history of present illness (what brought
you to the hospital?) not what happened 10
years ago
○ Medical history: past surgeries (to find out if they have a
stent or pacemaker, or problems with anesthesia), what
medications they are on, any supplements, how long have
they had a disease (hypertension, diabetes, hyperthyroid)
○ Demographic information: where they live, lifestyle, what
the patient has access to (patient just had heart surgery,
NEW Med Surg Exam 1 Review Chapter 25:
Introducing the Cardiovascular System 2022
