EKG Interpretation Flashcards
1
Q
What are the BEST leads for continous monitoring of ST segments depression?
A
V3-5, III, aVF - in this order
2
Q
What does lead II assess?
A
narrow QRS complexes
3
Q
What is conductance?
A
The ability to transmit electrical current - ions require open channels to move across membranes
4
Q
What is the Gate Theory?
A
consists of electrostatic gates – activated/inactivated depending on the electrical potential of the cell membrane
Gates for Na, K, Cl, and Ca
5
Q
What pump is on the cardiomyocyte? What does it do - how many Na vs K move? What is the source of energy?
A
Na-K pump; help with active transport of Na & K; energy source is 1 molecule of ATP; 3 Na ions out (increase extrecell) and 2 K ions in (increase intracell)
6
Q
What is the Na intracellular concentration?
A
10 mmol
7
Q
What is the Na extracellular concentration?
A
145 mmol
8
Q
What is the Na equilibrium potential?
A
60 mV
9
Q
What is the K intracellular concentration?
A
135
10
Q
What is the Na extracellular concentration?
A
4
11
Q
What is the K equilibrium potential?
A
-94
12
Q
What is the Cl intracellular concentration?
A
4
13
Q
What is the Cl extracellular concentration?
A
114
14
Q
What is the Cl equilibrium potential?
A
-97
15
Q
What is the Ca intracellular concentration?
A
10^-4
16
Q
What is the Ca extracellular concentration?
A
2
17
Q
What is the Ca equilibrium potential?
A
132
18
Q
How many phases in the LV action potential?
A
5 (phases 0-4)
19
Q
What happens at phase 0?
A
Na in
20
Q
What is the normal resting membrane
A
-90 mV
21
Q
What is the threshold potential?
A
-70 mV
22
Q
What ionic change happens at Phase 0?
A
Na in
23
Q
What antiarrhythmics function at Phase 0?
A
Class Ia (quinidine, procainamide)
Class Ib (lidocaine)
Class Ic (flecainide)
24
Q
What is the mV at Phase 1?
A
20
25
What ionic change happens at pahse 1?
K out
26
What are the correlating phases to depolarization, plateau, and repolarization?
P0 = depolarization
P1 = plateau
P2 = repolarization
27
What is ionic change is happening at phase 2?
Ca in, K out
28
What antiarrythmic class works at P2?
Class IV (calcium channel blockers)
29
What is the action potential between P2 and P3?
5 mV
30
What antiarrythmic class works at P3?
Class 3 (amiodarone)
31
What ionic change is occuring at P3?
K out
32
What antiarrythmic class works at P4?
Class II beta blockers & Class 1b Lidocaine
33
What potential does P0 start at, reach, and end?
Starts at -90 mV, reaches threshold potential of -70 mV to -65 mV, and ends at +20 mV
34
Are sodium channels fast or slow?
Fast
35
What part of the EKG does P0 correlate with?
QRS
36
What is the absolute refractory period? Are sodium channels active or inactive? Can an early depolarization be initiated?
Cardiac cell is completely unresponsive to any electrical stimulus; inactive; NO
37
The absolute refractory period lasts from phase ___ to phase ___
0 to 3
38
The relative refractory period lasts from middle of phase ____ to beginning of phase ____
middle of phase 3; beginning of phase 4
39
What is the membrane potential of phase 4?
-60 mV to -90 mV
40
Can a strong electrical stimulus cause depolarization?
Yes, if strong enough;
41
What does synchronized cardioversion do for the relative refractory period?
prevents the delivery of a shock during the T wave
42
Commotio Cordis
A sudden blow to the chest during the relative refractory period (e.g., in sports injuries) can induce ventricular fibrillation, leading to cardiac arrest.
43
P1 vs P2: which is repolarization and which is rapid/initial repolarization?
P1 is rapid/initial repolarization; P2 is repolarization
44
At P1: ____ gates close, slower influx of ____ begins, ____ moves out
Na; Ca; K
45
At P2: ____ moves in, ____ moves out
Ca in, K out
46
Are calcium channels slow or fast?
slow
47
Does Ca influx delay or expedite repolarization? Does Ca prolong or shorten absolute refractory period? How does this affect heart contraction time?
Delays; prolongs; increases time to contract
48
What phase if the terminal/rapid repolarization/recovery?
P3
49
P3: slow ____ channels close, ____ leaves the cell rapidly causing a ____decline in potential back to normal resting potential (-90 mV).
Ca; K; rapid
50
What phase is diastolic repolarization/resitng membrane potential?
P4
51
____ pump re-establishes the ionic balance. Are these pumps energy dependent?
Na-K; yes, they require ATP
52
What pump does digoxin inhibit?
Na-K pump
53
What ion is IMPORTANT in re-establishing the resting membrane potential?
K
54
What drug class antiarrythmic is Quinidine/Procainamide? What phase do they work on? What ion is blocked?
Class 1a; P0; Na
55
Quinidine/Procainamide ____ QT and ____duration of the AP
prolongs; increases
56
What syndrome can Procainamide diagnose? What other 2 cardiac condition can it be used for?
Brugada; VT and WPW
57
What is Brugada syndrome? What intervention can be used?
A genetic channelopathy affecting Na channels leading to disruption > syncope and sudden death. Place an ICD
58
What class antiarrhythmic is lidocaine?
Class Ib antiarrhythmic
59
What phases do Class Ib antiarrhythmics work on?
P0 & P4;
60
Class Ib antiarrhythmics block ____ channels and _____ duration of P4, _____ the duration of the AP causing _____QT
Na; lengthens; decreases; shortened
61
Class Ib antiarrhythmic ____ rate of HR
Decrease
62
Are class Ib antiarrhythmic useful for arterial arrythmias?
NO
63
What class antiarrythmic is Flecanide?
Class Ic antiarrhythmic
64
Do Class Ic antiarrhythmics affect AP duration or change QT interval?
NO
65
In what situations can Flecanide (Class Ic antiarrhythmic) be used?
SVT, AF & WPW w/o structural heart disease
66
What class antiarrythmic are BBs?
Class II
67
Class II antiarrythmics _____ the slope of phase ___ spontaneous depolarization
Decrease; 4
68
In what situations can BB (Class II antiarrhythmic) be used?
Rate control situations (Afib/Aflutter/ symptomatic SVT)
69
BB (Class II antiarrhythmic): inhibit ____ adrenergic activation of _____ cyclase and _____ intracellular _____ levels.
Inhibit beta adrenergic activation of adenylate cyclase and reduce intracellular cAMP levels – decreased SA node activity
70
Do BB increase of decrease SA node activity?
decrease
71
What class antiarrythmic are Potassium channel blockers?
Class III
72
Class III decrease _____ efflux out of the cell and _____ QT interval
K; prolongs
73
Amiodarone blocks what 3 ionic channels?
sodium, calcium, and potassium
74
Which medication is part BB and part K channel blocker? What is it used for?
Sotalol; prevention of AF and suppress ventricular arrhythmia
75
Does amiodarone increase or decrease SA/AV node conduction
decrease
76
What antiarrhythmic drug class are CCBs?
Class IV antiarrythmics
77
What medication are non dihydropyridine CCB?
Diltizem and verapamil
78
On what phases do Class IV (CCBs) work?
Phase 0 and 4 nodal AP & Phase 2 - myocardial AP
79
CCBs ____ conduction velocity and ____conduction through the AV node
decrease; slow
80
In what situations do you use CCBs (Class IV)?
Atrial tachycardias and SVT ventricular rate control
81
What is contractility? What is conductivity? What is automaticity?
Contractility: ability of the cardiac myocytes to contract
Conductivity: ability of cardiac cells to transmit electrical impulses
automaticity: cardiac cells to generate spontaneous action potentials without external stimulation
82
Cardiac action potentials are associated with what cells?
pacemaker cells
83
How many phases of Cardiac Pacemaker cells are there?
3 (P0, P3, P4)
84
Pacemaker: What phase is depolarizatoin, repolarization, and gradual repolarization?
P0 = depolarization
P3 = repolarization
P4 = gradual repolarization
85
Pacemake Cells P0: begin at what threshold potential?
-40 mV
86
Pacemaker Cells P0: influx of ____ ions results in a gradual stroke in membrane potential from ____ mV to ___ mV
Ca; upstroke; -40 mV to +10
87
Pacemaker Cells P3: ___ channels close, ___ moves out of the cell, rapid ____ of membrane potential from ___ mV to ___ mV
Ca; K; decrease; +10 to -60mV
88
Pacemaker Cells P4: slow influx of ___ ions, membrane potential changes from ___ mV (resting membrane potential) to ___ mV (threshold potential)
Na; -60 mV to -40 mV,
89
Pacemaker Cells: Does the slope of P4 determine HR?
Yes
90
What is the SA node rate; AV node rate; Bundle of HIS/Purkinje fibers rate?
SA: 60-100 bpm
AV: 40-60 bpm
Bundle of HIS/Purkinje: 20-40 bpm
91
Cardioplegia
Arrests the heart in diastole by preventing repolarization - locked Na channels
92
What is Ca IV used for in regards to the heart?
Used for hyperkalemia to protect heart and increase the period between RMP and TP
93
Where does the nervous system of the heart originate?
The NTS of the medulla oblongata
94
What are the 3 sensory inputs to the heart?
Proprioceptors, chemoreceptors, Baroreceptors
95
What is the overall goal of autonomic regulation of the heart?
Maintain CO
96
Define: Inotroppy, Chronotropy, Lusotropy, Dromotropy
Inotropy - increased contractility
Chronotropy - increased HR
Lusotropy - increased relaxation time
Dromotropy - increase AV impulse conduction
97
Cardiac: Is the the SNS located subepicardially? Innervates what? Does the gradient travel apex to base or base to apex?
Yes; innervates atria and ventricles; base to apex
98
Is the stellate ganglia the efferent or afferent component of the sympathetic trunk?
efferent
99
Which nerves receive impulse to cause NE release?
Cardioaccelerator (T1-T4)
100
Binding of NE to B1 causes increased ___ entry through the slow ___ channels in contractile fibers of the ___ & ___ ventricles AND intrinsic rate of discharge of ___node
Ca; Ca; atria & ventricles AND increases; SA
101
With increased Ca, does the the slope of P4 increase or decrease?
increase
102
With increased intrinsic rate, is there an increase or decrease of spontaneous depolarization? Does this cause pacemaker cells to fire impulses quicker or slower? Does this slow or increase the HR?
Increase; quicker; increases
103
What percent of Beta receptors are B1? Which B type is predominant?
70%; B1
104
B1 increase or decrease: Automaticity, contractility, conduction velocity, HR/SA node firing?
All INCREASE
105
From what ganglia do postganglionc sympathetic cardiac neurons release NE?
Stellate ganglia
106
What percent of B receptors are B2
30%
107
Do B2 receptors cause vasodilation or vasoconstriction of cornary arteries, increase or decrease contractility, and increase or decrease HR?
vasodilation; increase; increase
108
Can B2 compensate for downregulated B1 receptors in CHF?
Yes
109
What NTs activate B2?
Epi and NE
110
Are B3 receptors active? Do they stimulate negative or positive inotropic effects?
Inactive; negative
111
Where can you find A1 receptors?
Near major arteries (Aorta, Pulmonary Arteries, Mesenteric Vessels and Coronary Arteries)
112
What is Prinzmetal’s angina?
Epicardial coronary artery vasoconstriction
113
What happens with vascular A2 stimulation and central A2 stimulation
Vascular and Central
114
What happens with vascular alpha 2 stimulation?
transient vasoconstriction
115
What happens with central alpha 2 stimulation?
decrease in blood pressure by inhibiting central sympathetic outflow
116
Which histamine stimulation causes Increases intracellular calcium, Coronary artery vasoconstriction, and Decreased conduction through AV node
H1 stimulation
117
Which histamine stimulation causes Coronary artery vasodilation, Increased myocardial contractility
Increased HR
H2
118
What is direct stimulation of SNS
119
What are 3 indirect stimulations of the SNS?
- Adrenal medulla releases Epi & NE > activate A1, B1, B2 in the heart
120
Which NT has a greater effect on increasing CO
NE
121
SNS stimulation of heart manifestations
Increased HR, Increased Contractility
122
Does SNS stimulation cause increased metabolic rate?
Yes
123
Will the coronary arteries dilate or constrict to increase flow according to metabolic needs of heart
dilate
124
The PNS innervates ___ & ___ nodes and ___
125
is there PNS activity in the ventricles?
No, not really
126
What CN mediates the PNS?
Vagus - CN X
127
Is the PNS predominant when the heart is active or at rest?
at rest
128
What is the goal of the PNS in regards to the heart
to slow the HR via vagal impulse
129
What muscarinic recepetor is released in the heart by the PNS?
M2
130
PNS indirect or direct: ____ stimulation by centers located in spinal cord, brain stem, and hypothalamus
direct
131
Is there indirect PNS stimulation form adrenal medulla
NO
132
SNS stimulation of heart manifestations
Decreased HR & Decreased Contractility
133
PNS stimulation results in _____ Myocardial O2 consumption (MVO2) and indirectly _____ coronary arteries
decreased; constricts
134
Hypokalemia EKG Changes (ST, T wave, U wave)
depressed ST segment, inverterd T wave, Prominent U wave
135
Hyperkalemia EKG Changes (ST, T wave, PR, QRS)
ST segemnet elevation, Peak T wave, Prolonged PR, Widened QRS complex
136
Hypocalcemia EKG Changes (QT, ST wave, arrhythmias)
prolonged QT, prolonged ST, V tach
137
Hypocalcemia EKG Changes (QT, ST wave, T wave)
Short QT interval, short ST segment, wide T wave
138
Hypomag EKG Changes (ST wave, T wave, Prolonged QT )
Depressed ST segment, inverested T wave, prolonged QT interval
139
Hypermag EKG Changes (QRS, PR interval )
Widened QRS, prolonged PR interval
