Cardiac Structure And Function Flashcards
(151 cards)
1
Q
Primary function of the heart
A
Generate pressure to drive blood flow to tissues
2
Q
The sequence of events with each heartbeat including diastole and systole
A
Cardiac Cycle
3
Q
The total blood flow per minute in the cardiovascular circuit
A
Cardiac Output (CO)
4
Q
Cardiac output equation
A
CO = HR x SV
5
Q
What are the four chambers of the heart?
A
R atrium, R ventricle, L atrium, L ventricle
6
Q
The _____ side of the heart pumps blood to the lungs, while the _____ side of the heart pumps blood to the body
A
Right; left
7
Q
Structures that travel away from the heart carrying oxygenated blood to the tissues
A
Arteries
8
Q
Oxygen is transferred to tissues through
A
Diffusion
9
Q
The movement of molecules from an area of high concentration to an area of lower concentration
A
Diffusion
10
Q
Diffusion of water across a semipermeable membrane
A
Osmosis
11
Q
Deoxygenated blood returns to the _____ system
A
Venous
12
Q
Structures that travel towards the heart carrying deoxygenated blood
A
Veins
13
Q
What are the three layers of the heart wall?
A
Epicardium, myocardium, endocardium
14
Q
Visceral layer of the serous pericardium
A
Epicardium
15
Q
The middle and most prominent layer of the heart wall composed of cardiac muscle
A
Myocardium
16
Q
Why is the left side of the heart thicker than the right?
A
It pumps blood to the rest of the body, so it requires more muscle
17
Q
Layer of the heart wall that lines the cardiac chambers
A
Endocardium
18
Q
Structures that open and close valves
A
Papillary muscles
19
Q
The papillary muscles are connected to the heart valves via the
A
Chordae tendineae
20
Q
AV valves
A
Mitral and tricuspid
21
Q
Semilunar valves
A
Pulmonary and aortic
22
Q
Which valves close to make the S1 or “lub” sound?
A
Tricuspid and mitral
23
Q
Which valves close to make the S2 or “dub” sound?
A
Aortic and pulmonic
24
Q
Tips for listening to heart sounds
A
Concentrate, avoid auscultating through clothing or dressing, keep stethoscope tubing off body and other surfaces
25
S1 or “Lub” marks the beginning of
Systole (contraction)
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S2 or “dub” marks the beginning of
Diastole (relaxation/filling)
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Flow of blood through the heart
Superior and inferior vena cava, right atrium, tricuspid valve, right ventricle, pulmonic valve, pulmonary artery to lungs, pulmonary veins, left atrium, mitral valve, left ventricle, aortic valve, aorta, body
28
Which valve controls blood flow from the left atrium to the left ventricle?
Mitral (left AV valve)
29
Which valve controls blood flow from the right atrium to the right ventricle?
Tricuspid (Right AV valve)
30
Which valve controls blood flow from the right ventricle to the pulmonary artery and lungs?
Pulmonic valve
31
Which valve controls blood flow from the left ventricle to the aorta?
Aortic valve
32
Cardiac impulses pass from the atrium to the ventricles though the
Conduction pathway
33
Cardiac conduction pathway
SA node, AV node, bundle of his, left and right bundle branches, purkinje fibers
34
Spontaneous electrical activity generates
Regular rhythm of muscle contractions or heart rate
35
The heart’s pacemaker
Sinoatrial (SA) node
36
Typical rate of the SA node
60-100 bpm
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Typical rate of the atrioventricular (AV) node
40-60 bpm
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Function of AV node
Slows impulse conduction between atrium and ventricle, allowing atrium to fill ventricles with blood before ventricles contract
39
If SA and AV nodes fail, ventricles can generate their own impulse at a rate of
20-40 bpm
40
What shows electrical activity of the heart recorded by skin electrodes?
ECG
41
When the heart cells are resting or negatively charged on the inside, they are __________
Polarized
42
What causes contraction?
The movement of sodium inside cells due to increase permeability as a result of electrical changes.
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After contraction, sodium moves back out of cells causing relaxation or __________
Repolarization
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Concentration of ions inside and outside of cells
Primarily sodium (Na) outside, potassium (K) inside
45
What does a P-Wave represent?
Atrial depolarization
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Normal duration of P-Wave
<0.8 seconds
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PR interval is measured from
The beginning of P-Wave to the beginning of QRS
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What does the PR interval represent?
The time the electrical impulse takes to travel from SA node through AV node, His-pukinje system, to activate ventricular myocardial cells
49
Normal duration of PR interval
120-200 ms OR 0.12-0.20 seconds
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What does a longer PR interval indicate?
AV block (1st degree)
51
What does a shorter PR interval indicate?
The impulse is bypassing the AV node (ex: WPW syndrome)
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PR interval is typically _____, but may be depressed in pericarditis
Flat
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What does the QRS complex represent?
Ventricular depolarization
54
Normal duration of QRS complex
0.06-0.10 seconds
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What does a longer QRS complex suggest?
Disruption of conduction system (BBB, ventricular rhythms), and metabolic issues such as hyperkalemia and TCA OD
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The point at which QRS complex finished and ST segment begins
J point
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Negative deflections of QRS complex
Q (1st), S
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Positive deflection of QRS complex
R
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What does the ST segment represent?
The period when ventricles remain depolarized
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The ST segment is usually isoelectric, but may be depressed with
Ischemia, infarction, pericarditis
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What does the T-Wave represent?
Ventricular repolarization
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T-Waves are generally
Upright
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Inverted T-Waves can be a sign of
ischemia, LVH, metabolic abnormalities
64
Peaked T-Waves can be a sign of
Hyperkalemia or very early MI
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Normal duration of T-Wave
<160 ms
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Beginning of QRS complex to end of T-Wave
QT interval
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Normal duration of QT interval
<440 ms
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Prolonged QT interval is risk factor for
Ventricular arrhythmias and sudden death
69
Causes of prolonged QT interval
Genetics or SE of certain medications
70
What does a U-Wave represent?
Papillary mm repolarization
71
What is happening during systole?
Ventricles contract, increasing BP in ventricles closes AV valves and opens pulmonic and aortic valves ejecting blood from ventricles into pulmonary artery and aorta
72
What is happening during diastole?
Ventricles empty and relax, AV valves open and semilunar valves close, blood leaves atria and fills ventricles
73
When pressure in ventricles exceeds pressure in atria, ___ valves close and _____ begins
M/T; systole
74
When pressure in the ventricles decreased ___ valves close
A/P
75
What causes valves to open?
Rising pressure
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Ventricular contraction (systole) accounts for ___ of the cardiac cycle
1/3
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Ventricular relaxation (diastole) accounts for ___ of the cardiac cycle
2/3
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How do you know when systole has occurred on a EKG?
Pulse is present
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What effect does rapid heart rate have on diastole?
Diastole is shortened inhibiting adequate ventricular filling and ejection
80
The cardiac cycle is both electrical and mechanical. Which happens first?
Electrical
81
Physical signs of cardiac cycle
Pulse, heart sounds, hemodynamic waveforms (correlated with EKG)
82
5 step process for rhythm interpretation
Determine is rhythm is regular/irregular, determine rate, is there a P Wave for every QRS?, is the PR interval regular?, measure the QRS interval
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What does the width/appearance of QRS indicate?
Ventricular conduction
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Normal sinus rhythm
60-100 bpm
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HR less than 60 bpm originating from the sinus node
Sinus bradycardia
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Characteristics of sinus bradycardia
Regular rhythm, P wave for each QRS, regular PR interval
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HR greater than 100 bpm originating from the SA node
Sinus tachycardia
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Characteristics of sinus tachycardia
Normal conduction/activity just faster at a rate between 100-180 bpm, P Wave for each QRS, regular PR interval
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Causes of sinus tachycardia
Fever/infection, stress, exercise, fear/anxiety, drugs, pain, anemia, low BP
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Sinus tachycardia treatment
Treat the cause
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Disorganized, uncoordinated twitching of atria muscles caused by rapid production of atrial impulses
Atrial fibrillation
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Characteristics of atrial fibrillation
Irregular rate (rapid/uncontrolled or slower/controlled), non-identifiable P-Wave, immeasurable PR interval, irregular baseline (“irregularly irregular”), no A/V synchrony (atrial and ventricle contraction), narrow QRS
93
Causes of atrial fibrillation
Atherosclerosis, HF, congenital heart disease, COPD, hypo/hyperthyroidism
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Atrial fibrillation S/S
May be asymptomatic, palpitations, dyspnea, pulmonary edema, dizziness
95
Atrial fibrillation management
Decrease ventricular rate <100, eliminate/treat cause, may try to convert to NSR, anticoagulation may be necessary
96
The patient’s perception that they are having trouble breathing
Dyspnea
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Atrial fibrillation increases the risk for
Stroke
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Loss of AV synchrony results in decreased
Ventricular filling
99
Abnormal rhythm that occurs in the atria in which atrial rhythm is regular, but fast
Atrial flutter
100
Characteristics of atrial flutter
Sawtooth appearance, atrial rate 250-400 bpm, uniform QRS but irregular in rate (more Ps than QRS), no AV synchrony
101
Causes of atrial flutter
HR, tricuspid or mitral valve disease, PE, inferior MI, carditis, dig. Toxicity
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Management for unstable atrial flutter with rate >150 bpm
Synchronized cardioversion
103
Management for stable atrial flutter
Drug therapy such as CCB & BB (for rate control) and anticoagulants (due to pooling of blood in atria)
104
Conduction defects within the AV junction that impair conduction of atrial impulses to ventricular pathways
AV blocks
105
Types of AV blocks
1st degree, 2nd degree (type I and II), 3rd degree
106
Rhythms that originate above the AV junction usually have a __________ QRS. Those that originate below are usually _________.
Narrow; wide
107
Characteristics of 1st degree AV blocks
Regular, rate usually 60-100 bpm, regular but prolonged PR interval (>0.2 sec), asymptomatic
108
Causes of 1st degree AV block
Inferior wall MI or ischemia, hyper/hypokalemia, digoxin toxicity, hypoxemia, some medications
109
1st degree AV block management
Correction of underlying cause, atropine if symptomatic bradycardia develops
110
Medications that inhibit AV node conduction
BB, CCB, digoxin, amiodarone
111
Characteristics of 2nd Degree AV block Type I/Mobitz I
Regular atrial rhythm, irregular ventricular rhythm, PR interval progressively lengthens with each cycle until QRS is dropped for a cycle
112
Causes of 2nd degree AV block Type I/Mobitz I
Inferior wall MI, cardiac surgery, vagal stimulation, myocarditis, medications
113
S/S of 2nd degree AV Block Type I/Mobitz I AND Type II/Mobitz II
Asymptomatic, weakness, irregular pulse, vertigo
114
2nd degree AV Block Type I/Mobitz I management
Treat underlying cause, atropine or temporary pacemaker if symptomatic, discontinue digoxin if appropriate
115
Characteristics of 2nd degree AV block Type II/Mobitz II
Regular atrial rhythm, regular or irregular ventricular rhythm (depending on degree), constant PR interval, QRS periodically absent or disappears
116
Causes of 2nd degree AV block Type II/Mobitz II
Severe CAD, MI, idiopathic fibrosis, cardiac surgery, infections/inflammation, hyperkalemia, autoimmune disease
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2nd degree Type II/Mobitz II management
Transvenous or transcutaneous pacemaker, atropine, epinephrine, and dopamine if needed
118
Why is a pacemaker needed for 2nd degree AV block Type II/Mobitz II?
This rhythm can, and frequently does, progress to a third degree heart block (due to structural damage to conduction system of heart)
119
Characteristics of 3rd degree heart block
Regular atrial rhythm, regular ventricular rhythm slower than atrial rate, no relation between P waves and QRS (usually more P waves), no constant PR interval, QRS normal or wide/bizzare
120
Cause of 3rd degree heart block
Hypoxia, MI, dig. Toxicity, congenital abnormality, rheumatic fever
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S/S of 3rd degree heart block
Hypotension, angina, HF
122
3rd degree heart block management
Atropine, epinephrine, dopamine for bradycardia, pacemaker
123
Characteristics of junctional rhythm
Originates from AV node —> narrow QRS, absent P Wave, retrograde, behind QRS, or with short PR interval, loss of AV synchrony
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Typical junctional escape rhythm
40-60 bpm
125
Junctional bradycardia
<40 bpm
126
Junctional tachycardia
>100 bpm
127
Accelerated junctional rhythm
60-100 bpm
128
Junctional rhythm S/S
Asymptomatic, dizziness, dyspnea, syncope, fatigue
129
Junctional rhythm management
Treat cause if possible, medications, may require permanent pacemaker
130
Causes of junctional rhythm
Chest trauma, sick sinus syndrome, myocarditis, radiation therapy, medications, hypothyroidism, sleep apnea, increased ICP, neuromuscular disorders
131
Medications that can cause junctional rhythm
BB, CCB, digoxin, opioids, clonidine, adenosine, lithium, amitriptyline
132
Any rhythm faster than 100 bpm with 3 or more irregular beats in a row that originates distal to the bundle of his
Ventricular tachycardia
133
General characteristics of ventricular tachycardia
Fast rate, loss of atrial contraction resulting in incomplete ventricular filling, can be with or without pulse; responsible for most of the sudden cardiac deaths in US
134
Characteristics of short periods of ventricular tachycardia
Asymptomatic, can cause dizziness, CP, palpitations, hypotension, or other s/s of poor perfusion
135
Characteristics of longer periods of ventricular tachycardia
Dangerous, can lead to cardiac arrest and death
136
Causes of ventricular tachycardia
CAD, valve abnormalities, cardiomyopathy, electrolyte imbalance, MI, medications
137
Ventricular tachycardia WITH pulse management
Medications or synchronized cardioversion
138
Ventricular tachycardia WITHOUT a pulse management
IMMEDIATE defibrillation
139
Disordered electrical activity causing ventricles to quiver instead of contracting normally resulting in the inability of ventricles to pump blood forward
Ventricular fibrillation
140
Characteristics of ventricular fibrillation
Chaotically irregular pattern, initially course (easier to convert), becomes finer, fatal within minutes without treatment
141
Causes of ventricular fibrillation
CAD/ischemia, MI, scarring, cardiomyopathy, drug toxicity, electrical injury, heart surgery, extreme hypo/hyperkalemia,
142
Ventricular fibrillation S/S
Loss of consciousness, no pulse/respiration
143
Ventricular fibrillation management
Immediate defibrillation, followed by anti-arrhythmic medications. Survivors will likely require placement of implantable cardioverter-defibrillator (ICD)
144
Common dysrhythmia occurring in patient with/without heart disease caused by an ectopic cardiac pacemaker in the ventricle
Premature ventricular contractions (PVCs)
145
Characteristics of premature ventricular contractions (PVCs)
Premature and bizzarely shaped QRS complexes that are unusually long and appear wide on ECG, not preceded by P Wave; most often asymptomatic
146
Causes of premature ventricular contractions (PVCs)
Hypoxia, ischemia, myocarditis, CM, meds/illicit substances, electrolyte abnormalities
147
Premature ventricular contractions (PVCs) treatment
Treat causes, may require medication
148
Contractions of the atria that are triggered by atrial myocardium, but do not originate from SA nodes
Premature atrial contractions
149
Characteristics of premature atrial contractions
Typically have normal QRS, commonly idiopathic, often discovered incidentally
150
Causes of premature atrial contractions
CAD, CM, valvular heart disease, medications, CHF, MI, COPD
151
Premature atrial contractions S/S
Often asymptomatic, may experience SOB, anxiety, palpitations
