Download The Cardiovascular System

The Cardiovascular System
Lecture Hours:
Lab Hours:
10 hours
10 hours
Credit Hours:
1.50 units
Reading assigned:
Fundamentals of Respiratory Care, chapter 9
Clinical Assessment in Respiratory Care, chapter 4
Basic Clinical Lab Competencies, chapter 6
Suggested reading:
Foundations of Respiratory Care, chapters 6, 7
Respiratory Care, Principles and Practice, chapter 17
Essentials of Respiratory Care, chapters 9, 10
Course Description
The student will learn the basic anatomy and physiology of the cardiovascular system, including cardiac
cycling, and be introduced to cardiovascular disorders.
Educational Objectives
At the end of the course, the student will be able to:
1. List the key anatomic structures of the heart and vascular system.
2. State the pathway of the flow of blood from the right atrium through the heart and vascular
system until it returns to the right atrium.
3. Identify the structures and pathway of the electrical system of the heart.
4. Identify the parts of the electrocardiogram.
5. Identify basic rhythms of the electrocardiogram, including major life-threatening arrhythmias.
6. Define cardiac output, cardiac index, stroke volume, systemic vascular resistance, mean arterial
pressure, end-systolic pressure, end-diastolic pressure, and ejection fraction, listing normal
values for each.
7. State the structures of the vascular system.
8. List the anatomic areas that control heart rate and factors that affect them.
9. List the components of the blood and the normal values for each.
10. List the major electrolytes of the body and the normal values for each.
11. List the common cardiac and vascular disorders.
Performance Objectives
At the end of the course, in a laboratory setting, the student will be able to successfully:
1. Obtain a blood pressure, heart rate, and respiratory rate.
2. Obtain an electrocardiogram.
3. Given the necessary data, calculate cardiac output, cardiac index, mean arterial pressure,
systemic vascular resistance, and ejection fraction.
Lesson Plan
I.
General information about the heart.
A. Size – about 4.8 inches high by 3.35 inches wide.
II.
III.
IV.
B. Weight – about .68 pounds in men and .56 pounds in women.
C. Number of beats – about 100,000 per day; 2.5 billion in 70 years.
D. Output – 2000 gallons per day; circulates blood through the system 1000 times per day.
E. System – 62,000 miles of arteries, veins, and capillaries.
F. Deaths – 7.2 million deaths per year from coronary artery disease.
Gross anatomy of the heart.
A. Pericardium.
1. Loose membranous sac in which the heart is located.
2. Minimizes friction during beating of heart.
B. Three layers.
1. Epicardium – outer layer continuous with the pericardium.
2. Myocardium – composed of bands of involuntary striated muscle fibers.
3. Endocardium – thin layer of tissue lining the inside of the heart.
C. Four chambers.
1. Two atria.
a. Thin-walled upper chambers.
b. Separated by the atrial septum.
c. Right side of septum has oval depression, the fossa ovalis cordis, the remnant of the
foramen ovale.
d. Function as receiving chambers for blood returning from the body and lungs.
2. The ventricles.
a. Lower chambers which make up the bulk of the muscle mass of the heart.
b. Left ventricle is ⅔ larger than right ventricle.
c. Right ventricle is thin-walled and oblong, like a pocket attached to the left ventricle.
d. Contraction of left ventricle pulls in right ventricle, aiding its contraction (called left
ventricular aid).
e. Separated by intraventricular septum.
D. Four valves.
1. Tricuspid valve – separates right atrium from right ventricle.
2. Pulmonic semilunar valve – separates right ventricle from pulmonary artery.
3. Bicuspid (mitral) valve – separates left atrium from left ventricle.
4. Aortic semilunar valve – separates left ventricle from aorta.
5. Chordae tendineae cordis.
a. Anchor free ends of A-V valves to papillary muscle.
b. Prevent A-V valves from pushing upward into the atria during ventricular
contraction.
Flow of blood.
A. Superior and inferior vena cava empty into right atrium.
B. Blood passes from right atrium through tricuspid valve to right ventricle.
C. Blood then goes through the pulmonic semilunar valve to pulmonary artery.
D. Blood then passes through the pulmonary capillary bed to pick up oxygen.
E. Blood then passes through the pulmonary vein and into the left atrium.
F. It continues through the mitral or bicuspid valve to the left ventricle.
G. From the left ventricle, the blood passes through the aortic semilunar valve to the ascending
aorta.
H. The blood travels through the various arteries to the capillary beds of the organs and tissue.
I. Veins carry the blood to the superior and inferior vena cava.
Coronary circulation.
V.
A. Arises from the root of the ascending aorta.
B. Left coronary artery.
1. Anterior descending artery – supplies anterior sulcus and apex.
2. Circumflex artery – supplies posterior side of left ventricle.
3. Together supply most of left ventricle, left atrium ⅔ of intraventricular septum, half of
intra-atrial septum, and part of right atrium.
C. Right coronary artery.
1. Posterior descending artery – supplies posterior intraventricular sulcus.
2. Has numerous smaller branches.
3. Together supply anterior and posterior portions of right ventricular myocardium, right
atrium, sinus node, posterior ⅓ of intraventricular septum, and portion of base of right
ventricle.
D. Coronary veins.
1. Closely parallel the arterial system.
2. Some coronary venous blood enters the heart through the Thebesian veins.
a. Thebesian veins empty directly into all chambers.
b. Those entering the left side of the heart create admixture with oxygenated blood
returning from the lungs, lowering the PaO2>
The vascular system.
A. Arteries.
1. Transport blood away from the heart.
2. Generally contain oxygenated blood; exception is the pulmonary artery.
3. Composed of three layers.
a. Tunica adventitia (external layer).
i.
Consists of connective tissue surrounding collagenous and elastic fibers.
ii.
Supports and protects the vessel.
iii.
Contains lymphatic vessels and nerve fibers.
iv.
Has fine vessels that provide its blood supply.
b. Tunica media (middle layer).
i.
Thickest layer.
ii.
Composed of concentrically arranged smooth muscle and elastic fibers.
iii.
Nerve fibers of tunica adventitia terminate in tunica media.
c. Tunica intima (internal layer).
i.
Thinnest layer of artery.
ii.
Consists of the epithelium – flat layer of simple squamous cells.
iii.
Common to all blood vessels including endocardium of the heart.
4. Large arteries termed conductance arteries or elastic arteries because tunica media has
less smooth muscle and more elastic fibers.
5. Medium sized arteries termed nutrient arteries because they control the flow of blood
to the various regions of the body; tunica media is composed almost entirely of smooth
muscle.
6. Arterioles.
a. Range in diameter from 20 – 50 µm.
b. Have thin tunica intima and adventitia, but a thick tunica media composed almost
entirely of smooth muscle.
c. Control blood flow to the capillary bed.
d. Called resistance vessels.
i.
Control rate of arterial runoff, rate at which blood leaves arterial tree).
VI.
ii.
Control arterial blood volume and, thereby, blood pressure.
B. Capillaries.
1. Consist of tunica intima.
2. Are the system of microcirculation.
3. Range in diameter from 5 to 10 µm.
4. Pre-capillary sphincter valves.
a. Smooth muscle rings at the proximal end of the capillary.
b. Contraction decreases blood flow.
c. Relaxation increases blood flow.
d. Responsive to local PaO2, PaCO2, pH, and temperature.
5. Called exchange vessels because they are the site of gas, fluid, nutrient, and waste
exchange.
C. Veins.
1. Transport deoxygenated blood back to the heart.
2. Generally contain deoxygenated blood; exception is pulmonary vein.
3. Composed of same layers as arteries, but are thinner.
4. Called capacitance or reservoir vessels because 70% to 75% of the blood volume is
contained in the venous system.
5. Peripheral veins contain one-way valves.
a. Valves formed by duplication of endothelial lining.
b. Found in veins > 2 mm in diameter.
c. Are in areas subjected to muscular pressure, e.g., arms and legs.
d. Prevent retrograde flow of blood.
6. Mechanisms aiding venous return to the heart.
a. Sympathetic venous tone.
b. Skeletal muscle pumping or “milking”, combined with one-way valves.
c. Cardiac suction.
d. Thoracic pressure differences created by respiratory efforts (thoracic pump).
The blood.
A. Functions of the blood.
1. Transport of respiratory gases to and from the tissue.
2. Provide antibodies for the defense mechanisms.
3. Carry nutrients to the cells and waste products from the cells.
4. Transport electrolytes, proteins, water, and hormones to allow the various functions of
the tissue to be accomplished.
5. Contains platelets and clotting factors for hemostasis.
B. Total blood volume: 60 – 80 mL/kg of body weight.
C. Components of the blood.
1. Plasma.
a. Whole blood minus the cellular component.
b. Pale yellow (straw-like) color.
c. Components of plasma.
i.
Water – approximately 90% of volume.
ii.
Proteins.
a) Approximately 7 – 9% of plasma.
b) Three types: albumin (60-80%), globulins, and fibrinogen
2. Erythrocytes or red blood cells (RBCs).
a. Generated in red bone marrow from the hemocytoblast, a common stem cell by the
process of erythropoiesis.
b. Bi-concave in structure.
c. Approximately 7 µm in diameter and 2 µm thick.
d. Mature RBCs have no nucleus (anucleated).
e. Have a semi-permeable membrane.
i.
If placed in hypotonic solution, will swell and rupture (hemolysis).
ii.
If placed in hypertonic solution, will shrivel (crenation).
f. Normal values.
i.
Males: 4.6 – 6.2 x 106/mm3.
ii.
Females: 4.2 – 5.4 x 106/mm3.
g. Contain hemoglobin, the molecule that allows transport of oxygen.
h. Normal hemoglobin values.
i.
Males: 13.5 – 16.5 g/dL.
ii.
Females: 12 – 15 g/dL.
i. Hematocrit.
i.
Percentage of RBCs in the whole blood by volume.
ii.
Normally three times hemoglobin.
iii.
Normal value.
a) Males: 42 – 54%.
b) Females: 38 – 47%.
3. Reticulocytes.
a. RBCs newly released from marrow that retain a small portion of the hemoglobin
forming endoplasmic reticulum.
b. Hemoglobin formation completed within two to three days of release, at which time
the endoplasmic reticulum disappears.
c. Percentage of RBCs that are reticulocytes indicates the rate of erythropoiesis.
d. Normal value: 0.5 – 1.5%.
4. Leukocytes or white blood cells (WBCs).
a. Formed in the myeloid tissue.
b. Perform phagocytosis.
c. Normal value: 4500 – 11,500/mm3.
d. Broken down into five types.
i.
Neutrophils.
a) Have a diameter of approximately 10 µm.
b) Highly phagocytic.
c) Normal value: 40 – 75%.
ii.
Eosinophils.
a) Have a diameter of approximately 10 µm.
b) Have a bilobed nucleus.
c) Absorb an acid stain.
d) Are present in parasitic and allergic processes.
e) Normal value: 0 – 6%.
iii.
Monocytes.
a) Have a diameter of 10 to 15 µm.
b) Have crescent-shaped nucleus.
c) Cytoplasm contains granules.
d) Highly phagocytic.
e) Normal value: 2 – 10%.
Lymphocytes.
a) Have a diameter of 6 to 9 µm.
b) Have a round nucleus.
c) Cytoplasm appears clear.
d) Form antibodies that remain intracellular or form antibodies that are
released into the bloodstream.
e) Normal value: 20 – 45%.
v.
Basophils.
a) Have a diameter of 10 µm.
b) Have a nucleus that contains three to four lobes.
c) Readily absorb stain.
d) Contain heparin which serves to prevent coagulation at sites of
inflammation.
e) Normal value: 0 – 1%.
5. Megakaryocyte.
a. Specialized type of blood cell.
b. Fragments into small irregular pieces of protoplasm called thrombocytes or
platelets.
c. Have a diameter of 2 to 4 µm.
d. Have no nucleus.
e. Have a granular cytoplasm.
f. Function in clot formation.
g. Normal value: 150,000 – 400,000/mm3.
Blood pressures.
A. Systolic pressure.
1. Pressure during contraction phase of the heart.
2. Normal value: 100 – 140 mm Hg.
B. Diastolic pressure.
1. Pressure during the contraction phase of the heart.
2. Normal value: 60 – 95 mm Hg.
C. Mean arterial pressure.
1. Average pressure in the arterial system over a given time.
iv.
VII.
(2 𝑥 𝑑𝑖𝑎𝑠𝑡𝑜𝑙𝑖𝑐 𝑝𝑟𝑒𝑠𝑠𝑢𝑟𝑒)+ (𝑠𝑦𝑠𝑡𝑜𝑙𝑖𝑐 𝑝𝑟𝑒𝑠𝑠𝑢𝑟𝑒)
2. MAP =
3
3. Normal value: 70 – 105 mm Hg.
𝑉𝑜𝑙𝑢𝑚𝑒
4. Can also be expressed as MAP = 𝐶𝑎𝑝𝑎𝑐𝑖𝑡𝑦
D. Central venous pressure (CVP).
1. Reflects right atrial pressure.
2. Influenced by changes in right ventricular function.
3. Measured by insertion of catheter via the subclavian vein, internal jugular vein, or
external jugular vein.
4. Distal tip of catheter in superior vena cava just above right atrium.
5. Purpose of CVP monitoring.
a. Assess blood volume status.
b. Administer fluids.
c. Sample blood.
d. Measure SvO2.
VIII.
e. Assess right ventricular preload.
6. Normal values.
a. CVP: < 6 mm Hg.
b. Right atrial pressure (RAP): 2 – 6 mm Hg.
E. Pulmonary artery pressure (PAP).
1. Used to assess the filling pressures of the left side of the heart.
2. Measured by use of a flow-directed, balloon-tipped catheter.
3. Catheter is inserted via a peripheral vein (internal jugular, external jugular, subclavian,
basilica, or femoral); catheter is advanced through the heart into the pulmonary artery.
4. Used to measure hemodynamic parameters.
a. Pulmonary artery pressures – systolic, diastolic, and mean.
b. Right ventricular preload (via right atrial pressure).
c. Right ventricular afterload (via PA systolic pressure).
5. Normal values.
a. Pulmonary artery pressure, systolic: 20 – 30 mm Hg.
b. Pulmonary artery pressure, diastolic: 6 – 15 mm Hg.
c. Pulmonary artery pressure, mean: 10 – 20 mm Hg.
d. Pulmonary artery wedge pressure, mean: 4 – 12 mm Hg.
Cardiac output (CO).
A. Definition – total amount of blood pumped by the heart per minute.
B. Cardiac output = Heart rate x Stroke volume.
C. Normal value: 4 – 8 L/min.
D. Cardiac index (CI).
1. Definition – volume of blood pumped by the heart per minute (CO) divided by body
surface area.
𝐶𝑎𝑟𝑑𝑖𝑎𝑐 𝑜𝑢𝑡𝑝𝑢𝑡
2. CI =
𝐵𝑜𝑑𝑦 𝑠𝑢𝑟𝑓𝑎𝑐𝑒 𝑎𝑟𝑒𝑎
E. Stroke volume (SV).
1. Definition – amount of blood ejected from the ventricle with each ventricular cycle.
2. End-systolic volume (ESV) – volume remaining after systole.
3. End-diastolic volume (EDV) – volume to which the ventricles fill during diastole.
4. SV = EDV – ESV
5. Normal value: 60 – 130 mL/beat.
6. Ejection fraction (EF).
a. Definition – proportion of EDV ejected on each stroke.
𝑆𝑡𝑟𝑜𝑘𝑒 𝑣𝑜𝑙𝑢𝑚𝑒
b. EF = 𝐸𝑛𝑑−𝑑𝑖𝑎𝑠𝑡𝑜𝑙𝑖𝑐 𝑣𝑜𝑙𝑢𝑚𝑒
c. Normal value: 64%.
7. Factors affecting stroke volume.
a. Preload.
i.
Definition – initial stretch of ventricle.
ii.
The greater the preload, the greater the tension on contraction.
b. Afterload.
i.
Definition – force against which the heart must pump.
ii.
In clinical practice, left ventricular afterload equals SVR.
c. Contractility.
i.
Definition – amount of systolic force exerted by heart muscle at any given
preload.
ii.
Increases in contractility lead to higher EF, lower ESV, and higher SV.
iii.
iv.
IX.
Decreases in contractility lead to lower EF, higher ESV, and decrease SV.
Positive inotropism – higher stroke volumes for a given preload indicating an
increase in contractility.
v.
Negative inotropism – decreased stroke volumes for a given preload indicate a
decrease in contractility.
d. Heart rate.
i.
Central factors are main controls.
ii.
Cardiac output directly proportional to heart rate.
a) Relationship exists up to 160 to 180 beats/minute.
b) Filling time for ventricles insufficient at higher rates.
Systemic vascular resistance (SVR).
A. Definition – sum of all frictional forces opposing blood flow through the vascular circulation.
𝑀𝑒𝑎𝑛 𝐴𝑜𝑟𝑡𝑖𝑐 𝑃𝑟𝑒𝑠𝑠𝑢𝑟𝑒−𝑅𝑖𝑔ℎ𝑡 𝐴𝑡𝑟𝑖𝑎𝑙 𝑃𝑟𝑒𝑠𝑠𝑢𝑟𝑒
B. SVR =
𝐶𝑎𝑟𝑑𝑖𝑎𝑐 𝑂𝑢𝑡𝑝𝑢𝑡
X.
XI.
a. Mean aortic pressure – use systolic pressure.
b. Right atrial pressure – use central venous pressure.
C. Normal value: 15 – 20 mm Hg.
Cardiovascular control centers.
A. Medulla.
1. Stimulus to vasoconstrictor area increases output to adrenergic receptors in the smooth
muscle, causing vasoconstriction and increase in SVR.
2. Stimulus to cardioaccelerator area increases sympathetic discharge to SA and AV nodes,
causing increase in heart rate.
3. Stimulus of the cardioinhibitory area increases vagal stimulation to the heart, causing a
decrease in heart rate.
4. Centers interact with each other to determine heart rate.
B. Cerebral cortex – send signals t the medulla in response to exercise, pain, or anxiety.
C. Hypothalamus – indirectly affects heart rate through medulla from its heat-regulating
function.
D. Peripheral receptors.
1. Baroreceptors.
a. One set located in aortic arch and carotid sinuses – monitor arterial pressures
generated by left ventricle.
b. Second set located in walls of atria and large thoracic and pulmonary veins –
respond to changes in vascular volume.
c. Response of receptors directly proportional to stretch on the vessel wall.
2. Chemoreceptors.
a. Located near the high pressure sensors in the aortic arch and carotid sinuses.
b. Sensitive to changes in blood chemistry.
c. Strongly stimulated by decreased oxygen tension.
d. Also stimulated by low pH or high carbon dioxide levels.
E. Central chemoreceptors.
1. Located in medulla.
2. Respond to hydrogen ions in the cerebral spinal fluid.
3. Indirectly respond to carbon dioxide level.
Properties of heart muscle.
B. Excitability – ability to respond to electrical, chemical, or mechanical stimulation.
C. Automaticity.
XII.
1. Ability of cardiac muscle to initiate a spontaneous electrical impulse.
2. Highly developed in specialized areas – pacemaker of nodal tissue.
D. Conductivity – ability to radiate electrical impulses.
E. Contractility – ability to contract in response to an electrical impulse.
Basic electrocardiography.
A. Terms.
1. Polarization – difference in electrical potential between two points in tissue; the resting
state of cardiac muscle.
2. Depolarization – influx of sodium into the interior portion of the cells.
3. Repolarization – rapid return of the cell to the polarized state.
B. Pathway of the electrical impulse.
1. Sino-atrial (SA) node.
a. Located in upper portion of right atrium.
b. Has greatest degree of automaticity.
c. Normal pacemaker of the heart.
2. Atrio-ventricular (AV) node.
a. Located in intraventricular septum.
b. Has second greatest degree of automaticity.
c. Backup to the SA node in the event of failure.
3. Bundle of His.
a. Located on right side of intraventricular septum.
b. Conducts the impulse from the AV node to the left and right bundle branches.
4. Bundle branches.
a. Located in the interventricular septum.
b. Divide into one right and two left bundle branches.
c. Conduct the impulse to the Purkinje fibers.
5. Purkinje fibers.
a. Located throughout the endocardial layer of both ventricles travelling in a superior
direction from the apex of the heart.
b. Depolarization begins when the electrical impulse leaves the Purkinje fibers and
travels from the endocardial layer outward toward the epicardium and from the
apex to the base of the ventricles.
C. The electrocardiogram.
1. ECG tracing.
a. Larger square – 0.2 seconds
b. Smaller square – 0.04 seconds
c. Determination of heart rate.
2. P wave.
a. Produced by atrial depolarization.
b. Normally 0.06 to 0.11 seconds in duration.
3. QRS complex.
a. Produced by ventricular depolarization.
b. Normally 0.03 to 0.12 seconds in duration.
c. Repolarization of the atria occurs simultaneously with the QRS complex and is
hidden by the QRS complex.
4. T wave.
a. Produced by ventricular repolarization.
b. Normally 0.14 to 0.26 seconds.
5. PR interval.
a. Time from beginning of atrial depolarization to beginning of ventricular
depolarization.
b. Normal interval is 0.12 to 0.20 seconds.
6. RR interval.
a. Time from peak of one QRS complex to the peak of the next QRS complex.
b. Normally 0.6 to 1.0 seconds.
c. Used to measure the total cardiac cycle.
7. PP interval.
a. Time from beginning of one P wave to the beginning of the next P wave.
b. Normally equal to the RR interval.
c. Also used to measure total cardiac cycle.
Event
Time
P wave
0.06 – 0.11 seconds
PR interval
0.12 – 0.20 seconds
QRS complex
0.03 – 0.12 seconds
T wave
0.14 – 0.26 seconds
PP/RR intervals
0.60 – 1.00 seconds
8. ECG leads.
a. Lead I – negative electrode on right arm, positive electrode on left arm.
b. Lead II.
i.
Negative electrode on right arm, positive electrode on left leg.
ii.
Used most commonly in acutely ill patients with leads placed on chest rather
than on limbs.
c. Lead III – negative electrode on left arm, positive electrode on left leg.
d. Leads I, II, and III comprise Einthoven’s triangle and represent electrical activity of
the heart from three different orientations.
e. Precordial leads.
i.
Leads V1, V2, V3, V4, V5, and V6.
ii.
V1 – positive electrode placed at right sternal margin and fourth intercostal
space.
iii.
Successive leads placed laterally to the left with V6 at mid-axillary line.
iv.
Electrical activity measured from six different locations and depicted
differently for each lead.
D. Basic rhythms.
1. Normal sinus rhythm.
2. Sinus bradycardia.
a. Rate less than 60/min.
b. Rhythm regular.
c. Causes.
i.
May be normal variation.
ii.
Trained athlete.
iii.
Sleep.
iv.
Sick sinus syndrome.
d. Symptoms.
i.
Syncope.
ii.
Lethargy.
iii.
Dizziness/lightheadedness.
iv.
Intolerance to exercise.
3. Sinus tachycardia.
a. Rate greater than 100.
b. Rhythm regular.
c. Causes.
i.
Anxiety.
ii.
Fever.
iii.
Pain.
iv.
Dehydration.
v.
Hypoxemia.
vi.
Anemia.
d. Symptoms.
i.
Anxiety, fear, or panic.
ii.
Pounding in chest.
4. Atrial fibrillation.
a. Rate of 100 to 160/min.
b. Rhythm irregular.
c. P waves absent or replaced by irregular activity.
d. QRS may be narrowed.
e. Most common arrhythmia.
f. Causes.
i.
Impulses originate in atria or pulmonary veins.
ii.
Hypertension.
iii.
Hyperthyroidism.
iv.
Primary heart disease.
g. Symptoms.
i.
Palpitations.
ii.
Shortness of breath.
iii.
Exercise intolerance.
iv.
Clot formation within heart, brain, lungs, legs, etc.
v.
Dizziness, somnolence, decreased level of consciousness.
h. Treatment.
i.
Anti-coagulants.
ii.
Beta blockers.
iii.
If symptomatic, oxygen, cardioversion.
5. Atrial flutter.
a. Rate of 110-140/min.
b. Regular rhythm.
c. P wave absent, replaced by “shark tooth” electrical activity.
d. Causes.
i.
Cardiomyopathy.
ii.
Hypertension.
iii.
Coronary artery disease.
iv.
Valvular disease.
e. Symptoms.
i.
Palpitations.
ii.
Shortness of breath.
iii.
Exercise intolerance.
iv.
Clot formation within heart, lungs, brain, legs, etc.
v.
Chest pain.
f. Treatment.
i.
Anticoagulants.
ii.
Beta blockers.
iii.
Anti-arrhythmic drugs.
iv.
Calcium channel blockers.
v.
If symptomatic, oxygen, medications, cardioversion.
6. Supraventricular tachycardia.
a. Rate of 140-220.
b. Rhythm is regular.
c. P wave absent.
d. Causes.
i. Coronary artery disease.
ii. Thyroid disease.
iii. COPD.
iv. Caffeine.
v. Stress.
e. Symptoms.
i.
Palpitations.
ii.
Dizziness.
iii.
Anxiety.
iv.
Chest pain.
v.
Loss of consciousness.
f. Treatment.
i.
Vagal maneuvers.
ii.
Carotid massage.
iii.
Cardioversion.
iv.
Medication – adenosine.
v.
Oxygen.
vi.
Ablation.
vii.
Pacemaker.
7. First degree heart block.
a. Rate is normal.
b. Rhythm is regular.
c. Normal P waves and QRS intervals.
d. P-R interval prolonged.
e. Causes.
i.
Conduction delay through the AV node due to nodal disease.
ii.
Acute MI.
iii.
Myocarditis.
iv.
Electrolyte imbalance.
f. Treatment – usually none; treat underlying cause.
8. Second degree heart block, type I (Wenckebach or Mobitz I).
a. Rate normal to slow.
b. Rhythm is irregular.
c. P waves normal, but faster than QRS.
d. P-R interval progressively lengthening until a QRS complex is dropped.
e. Causes.
i.
Primarily caused by disease of AV node.
ii.
High vagal tone, especially in athletes.
iii.
History of MI.
f. Symptoms – usually asymptomatic, but may have lightheadedness, dizziness, and
syncope.
g. Treatment – none if asymptomatic; if symptomatic, then pacemaker and atropine.
9. Second degree heart block, type II (Mobitz II).
a. Rate slow to normal.
b. Rhythm is regular.
c. P waves normal, but faster than QRS rate.
d. QRS interval prolonged.
e. PR interval normal or prolonged, but constant.
f. Cause – disease of distal conduction system (bundle of His, bundle branches,
Purkinje fibers.
g. Symptoms.
i.
Lightheadedness, dizziness, syncope.
ii.
Can lead to complete heart block, asystole, and death.
h. Treatment- none if asymptomatic; if symptomatic, then pacemaker, atropine, CPR.
10. Third degree heart block (complete heart block).
a. Rate slow.
b. Rhythm is regular.
c. P waves unrelated to QRS.
d. QRS interval prolonged.
e. PR interval variable.
f. Causes.
i.
Contractions result from a focus within the ventricle.
ii.
Acute anterior wall MI.
iii.
Concomitant dosages of beta blockers.
iv.
Vagal hypertonicity.
v.
Cardiomyopathy.
vi.
Electrolyte imbalance.
g. Symptoms.
i.
Lightheadedness, syncope, altered level of consciousness.
ii.
Chest pain.
iii.
Congestive heart failure.
iv.
Diaphoresis.
v.
Pallor.
vi.
Tachypnea.
vii.
Hypoxemia.
viii.
Decrease in cardiac output.
h. Treatment.
i.
Transcutaneous pacing.
ii.
Oxygen.
iii.
IV medication – atropine, dopamine, epinephrine.
iv.
CPR.
11. Monomorphic ventricular tachycardia.
a.
b.
c.
d.
e.
Rate of 180-180/minute.
Regular rhythm.
P waves not seen.
QRS interval prolonged.
Causes.
i.
Abnormal tissue in ventricles generating rapid, irregular heart rhythm.
ii.
Acute MI.
f. Symptoms.
i.
Decreased cardiac output leading to cardiogenic shock.
ii.
Asystole.
iii.
Cardiac arrest.
iv.
Hypotension.
v.
Decreased level of consciousness.
vi.
Hypoxemia.
vii.
Congestive heart failure.
viii.
Angina.
g. Treatment.
i.
If patient stable, then sedation with cardioversion, adenosine, oxygen.
ii.
If unconscious, immediate cardioversion, amiodarone, adenosine, oxygen.
12. Ventricular fibrillation.
a. Rate 300 +.
b. Irregular rhythm.
c. P waves not seen.
d. QRS complex unrecognizable.
e. Treatment.
i.
CPR.
ii.
Cardioversion.
iii.
Epinephrine.
iv.
Vasopressors.
13. Asystole/pulseless electrical activity (PEA).
a. Rate 0.
b. Flat line or non-perfusing rhythm.
c. No P waves.
d. QRS complex unrecognizable.
e. Treatment – immediate CPR.
14. Acute MI.
a. Rate varies.
b. Rhythm may be regular or irregular.
c. P waves may be normal or abnormal.
d. QRS complex may be normal or abnormal.
e. S-T segment does not go isoelectric – elevated S-T.
f. Causes.
i.
Coronary artery disease.
ii.
Psychological or physical stress.
iii.
Underlying risk factors.
g. Symptoms.
i.
Anxiety, feelings of fear or panic, altered level of consciousness..
ii.
Chest pain, sensation of pounding, radiating pain.
XIII.
iii.
Sweating, cold, clammy skin.
iv.
Shortness of breath.
v.
Hypoxemia.
h. Treatment.
i.
Thrombolytic therapy.
ii.
Coronary artery bypass graft (CABG).
iii.
Stents.
iv.
Angioplasty.
v.
Oxygen.
vi.
Anticoagulants.
vii.
Aspirin.
Cardiovascular pathophysiology.
A. Cardiac failure.
1. Definition – “an abnormality of cardiac function causes the heart to fail to pump blood
at a rate required for metabolizing tissues or when the heart can do so only with
elevated filling pressure” (National Heart, Lung, and Blood Institute).
2. Etiology.
a. Coronary artery disease.
b. Hypertension.
c. Idiopathic dilated cardiomyopathy.
d. Acute ischemia.
e. Valvular disease.
f. Arrhythmias.
g. Myocardial infarction.
3. Pathophysiology.
a. Primary impaired myocardial contractile failure.
i.
Ischemia.
ii.
Dilated cardiomyopathy.
iii.
Myocarditis.
b. Excessive ventricular load.
i.
Hypertension.
ii.
Aortic stenosis.
iii.
Pulmonary embolism.
iv.
Pulmonary hypertension.
v.
Mitral regurgitation.
vi.
Aortic regurgitation.
vii.
Pulmonary regurgitation.
viii.
Tricuspid regurgitation.
ix.
Septal defects.
c. Restricted ventricular filling.
i.
Restrictive cardiomyopathy.
ii.
Constrictive pericarditis.
iii.
Tamponade.
iv.
Mitral stenosis.
v.
Tricuspid stenosis.
d. Derangement results in excess pressure requirement of excess volume requirement.
e. Continued excess requirement leads to failure of adaptive mechanisms.
f. Failure of adaptive mechanisms leads to systolic dysfunction.
g. Failure of the left ventricle leads to back up of pressure and volume into the
pulmonary capillary bed.
i.
Increase in pulmonary capillary pressure (up to 28 mm Hg).
ii.
Increase in caliber of capillary vessels.
iii.
Engorgement of the lungs with blood.
iv.
Reduction in caliber of small airways due to pressure of vessels.
v.
Increase in lung elasticity, airway resistance, and work of breathing.
h. Increase in capillary pressure leads to leakage of blood into the alveoli.
i. Pulmonary edema (congestive heart failure) results.
4. Treatment.
a. Pharmacotherapy.
i.
Vasodilators.
ii.
Diuretics.
iii.
Digitalis.
iv.
Inotropic agents.
v.
Beta blockers.
vi.
Anti-arrhythmia agents.
vii.
Anti-coagulants.
b. Intra-aortic balloon pump.
c. Ventricular assist device.
d. Automated implantable cardioverter defibrillators.
B. Myocardial infarction (MI or heart attack).
1. Etiology – blockage or impairment of flow to coronary arteries.
2. Pathophysiology.
a. Formation of blood clot at the site of rupture of an atherosclerotic plaque on inner
wall of coronary artery.
b. Ischemic tissue distal to clot leads to areas of necrosis.
c. Presence of necrotic tissue impairs function of ventricles.
d. May lead to lack of blood flow to vital organs and/or back-up of blood in lungs
(pulmonary edema).
3. Risk factors.
a. Elevated cholesterol level.
b. Hypertension.
c. Smoking.
d. Diabetes.
e. Family history.
4. Treatment.
a. Pharmacotherapy.
i.
Anti-platelet therapy.
ii.
Anti-coagulant therapy.
iii.
Clot dissolving drugs.
iv.
Angiotensin converting enzyme (ACE) inhibitors.
v.
Beta blockers.
vi.
Oxygen therapy.
b. Surgical intervention.
i.
Coronary artery bypass graft (CABG).
ii.
Coronary angioplasty.
iii.
Coronary artery stints.
C. Cor pulmonale (right-sided heart failure).
1. Etiology – excessive pressure communicated to right ventricle.
2. Pathophysiology.
a. Increase in pressure in pulmonary vasculature leads to excessive work load for right
ventricle.
b. Increase in size of muscle of right ventricle (right ventricular hypertrophy).
c. Back up of blood into liver, jugular veins, extremities.
d. May lead to left-sided heart failure.
3. Risk factors.
a. Chronic obstructive pulmonary disease (COPD).
b. Pulmonary hypertension.
c. Pulmonary valvular stenosis.
d. Pulmonary embolism.
4. Treatment.
a. Pharmacotherapy.
b. Surgical intervention (in cases of stenosis).
D. Hypertension.
1. Etiology.
a. Primary (essential) hypertension – no specific cause; may be familial.
b. Secondary hypertension – caused by abnormality such as kidney disease.
2. Contributing factors.
a. High salt intake.
b. Obesity.
c. Lack of regular exercise.
d. Excessive alcohol of caffeine intake.
e. Smoking.
3. Pathophysiology.
a. Damage to blood vessels in the eye.
b. Arteriosclerosis.
c. Kidney failure.
d. Stroke.
e. Increased work load on cardiac muscle, leading to cardiac failure.
4. Treatment.
a. Pharmacological.
i.
Angiotensin converting enzyme (ACE) inhibitors.
ii.
Beta blockers.
iii.
Diuretics.
iv.
Calcium channel blockers.
v.
Alpha blockers.
vi.
Peripheral vasodilators.
b. Lifestyle changes.