ECG Flashcards
(202 cards)
1
Q
Steps for 12-lead ECG evaluation
A
- Axis 2. ST elevation, ST depression, inverted T’s 3. P wave characteristics 4. QRS complex, evidence of blocks, R wave progression 5. Ventricular hypertrophy? 6. QT interval
2
Q
Causes of Right Axis Deviation
A
RVH, Lateral wall MI, COPD, pulmonary embolus
3
Q
Causes of Left Axis Deviation
A
LVH, L anterior hemiblock, LBBB
4
Q
What is the physiologic reasoning for the pathologic causes of right axis deviation?
A
Acute or chronic cor pulmonale/ increased pulmonary venous pressures/vasoconstriction
5
Q
What is classified as ECG evidence of ischemia?
A
T wave inversion, ST depression >1mm
6
Q
What is classified as ECG evidence of injury?
A
ST segment elevation >1mm
7
Q
What is considered ECG evidence of Q Wave MI infarction?
A
ST elevation >1mm, T wave inversion, Q wave >25% of the R wave and >/= 0.4s
8
Q
What is considered ECG evidence of a non-Q-wave MI?
A
T wave inversion, ST depression >1mm
9
Q
What leads will show ECG changes in an anterior MI?
A
V1-6, mostly V3-5
10
Q
What leads show wave changes in an inferior MI?
A
II, III, aVF
11
Q
What leads show wave changes in a lateral MI?
A
I, aVL, V5, V6
12
Q
What leads show wave changes in a posterior MI?
A
V7-9, V1, V2 show tall broad initial R wave, ST segment depression, and tall upright T waves
13
Q
What leads show wave changes in an inferior posterior MI?
A
II, III, aVF, V6
14
Q
What leads show wave changes in an anteroseptal MI?
A
V1-4
15
Q
What leads show wave changes in an antero-posterior lateral MI?
A
V1-5, I aVL, V6
16
Q
Which leads show wave changes in a right ventricular MI?
A
ST elevation in V4R
17
Q
Which leads show wave changes in an anterolateral MI?
A
I, aVL, V4-6
18
Q
What is the criteria for diagnosis of MI in the setting of a LBBB or v-pacing?
A
Sgarbossa’s Criteria: ST segment elevation >/= 1mm in the same direction of primary QRS deflection, ST segment depression >/= 1mm in V2 & 3 (V1 also?), ST segment elevation >/= 5mm in the opposite direction of primary QRS deflection *suggested S wave mod: ST elevation greater than 1/4 depth of the S wave
19
Q
ECG criteria for Right Atrial Hypertrophy
A
Peaked in II, III, aVF (>2.5mm tall); biphasic V1 and V2 with upright > terminal
20
Q
ECG criteria for Left Atrial Hypertrophyyes
A
Wide in the limb leads (>/= 0.11mm); notched in II, III, and V4-6; biphasic V1 with terminal portion >1mmWhere should V1 be placed?
21
Q
What are the criteria for a left anterior fasicular block?
A
Left axis deviation >/= 30 degrees, qR in leads I and aVL, rS in leads II, III, and aVF
22
Q
ECG criteria for a left posterior fasicular block?
A
right axis deviation >120 degrees, rS in leads I and aVL, qR in leads II, III, aVF
23
Q
LBBB criteria
A
QRS >.1, notched/slurred R and no Q wave in lead I, notched/slurred R and no Q wave in aVL, rS or QS in V1, notched/slurred R and no Q in V6
24
Q
RBBB criteria
A
QRS >.1, tall R/slurred S in lead I, wide slurred S in aVL, rSR or Rabbit ears/wide notched R in V1, wide slurred S in V5, tall R/slurred S in V6
25
RVH criteria
Poor R wave progression with right axis deviation, R\>S/T wave inversion in V1, R
26
LVH criteria
left axis deviation, V6 R + V1 S = 35mm, S\>R V1-2, Tall R/R\>S in V5-6
27
What ECG changes are evidence of right ventricular strain?
ST depression and T wave inversion in leads III, aVF, V1-2
28
What ECG changes are evidence of left ventricular strain?
ST depression and T wave inversions in I, aVL, V5-6
29
What is the best way to calculate the QT interval?
1. Find the lead with the longest QT interval (usually V2-3) 2. Find and measure the length of the longest R-R interval in that lead (in seconds) 3. Measure the QT interval after the longest R-R (in seconds) 4. If HR \<60 use this QT measurement 5. If HR \>60 use the square root of the R-R interval
30
What type of cells primarily compose the SA node?
P cells
31
At what rate does the SA node generate impulses?
60-100 bmp
32
By which arteries is the SA node perfused?
55-60% RCA, remaining population perfused by a branch of the circumflex artery
33
Type of cells which comprise the AV node
T cells/Transitional cells
34
What is the purpose of the AV node?
To slow down impulses on the way to the ventricles (see PR segment), allows for complete atrial contraction prior to ventricular stimulation, leading to 15-20% greater volume/cardiac output
35
Coronary artery which supplies the AV node in 85-90% of people
RCA
36
Which bundle branch divides into an anterior/superior/thin and posterior/inferior/broad fascicle?
left
37
Coronary artery which supplies the anterior fascicle
LAD
38
Coronary arteries which supply the posterior fascicle
RCA and circumflex artery
39
Coronary arteries which perfuse the bundle of his
LAD and posterior descending coronary artery
40
Type of cells that make up the his bundle, bundle branches, and purkinje fibers
Purkinje cells
41
True or false: there are also nodal cells present in the ventricles
True, this is how ventricular rhythms occur when other pacemakers fail (usually results in a rate \<40)
42
What is unique about the automaticity of cardiac cells?
Any cell in the heart can exhibit it and generate a rhythm or dysrhythmia under the right circumstances
43
What kind of permeability does the sarcolemma exhibit?
Selective, via channels and gates
44
Name of the junctions which connect cardiac cells
Intercalated discs
45
Resting voltage of a cardiac cell
-60mV, primarily negative inside cell
46
What happens to a cell during depolarization?
Charge swaps from negative to positive inside
47
What four qualities do all cardiac muscle cells possess?
Automaticity, excitability, conductivity, contractility
48
What allows the sinus node to be the pacemaker and have the fastest rate of automaticity?
The high number of nodal cells which comprise it
49
What are the secondary or lateral pacemakers?
His bundle, junctional cells, ventricular purkinje cells
50
How does a cell depolarize?
Increased slow influx of sodium or calcium with decreased efflux of potassium until the membrane reaches its threshold of approximately -40mV (Phase 4) initiating an action potential
51
What do voltage do slow response cells reach as a result of threshold being reached and an action potential being initiated, disseminating an electrical impulse to other muscle cells?
0 mV (Phase 0)
52
What is phase 0 followed by in a pacemaker cell?
Phase 3 (Phases 1 & 2 do not exist): rapid depolarization caused by rapid efflux of potassium
53
Which cells are slow response cells?
Pacemaker cells
54
What are fast response cells?
All other cells
55
When purkinje cells (fast response cells) are at rest what is the membrane permeability like?
Permeable to potassium, relatively impermeable to sodium; allows for concentration gradient based potassium efflux causing relative intracellular negativity and extracellular positivity (approx a 90mV difference)
56
What is Phase 0 in fast response cells?
Rapid depolarization: impulse generated by pacemaker cells causes a sudden increase in sodium permeability in excitable myocardial and purkinje cells, causing sodium influx and cells to reach threshold at approximately -60 mV, opening fast sodium channels causing intracellular depolarization to 20 mV
57
What is phase 1 in fast response cells?
Channels for quick sodium influx close (H gates), a small efflux of potassium and a small influx of chloride occurs, causing decreased intracellular positivity until it is equal with the extracellular environment (~0 mV)
58
What occurs in phase 2 of fast response cells?
Plateau phase(\>100ms): slow calcium channels allow calcium in with some sodium, potassium exits cell allowing the maintenance of 0 mV membrane potential, calcium influx occurs triggering muscle contraction (excitation contraction coupling)
59
Where on an ECG are phases 1 and 2 represented?
ST segment
60
What is phase 3 in fast response cells?
Rapid repolarization: potassium efflux combined with channel inactivation returns cells to relative negativity
61
What part of the ECG represents rapid repolarization?
T wave
62
What occurs during phase 4 in fast response cells?
Activation of the sodium potassium pump to actively remove sodium and bring in potassium at a ratio of 3:2 returning the cell to its resting membrane potential, remaining stable at -90 mV until the next impulse is generated
63
In which direction does the heart depolarize?
From endocardium to epicardium
64
What does the P wave represent?
Atrial depolarization
65
How do the ventricles depolarize?
Beginning at the septum from left to right, down to the apex, and ending at the basal portion of each ventricle and septum
66
What does the QRS represent?
Ventricular depolarization
67
In which direction does the myocardium repolarize?
Epicardium to endocardium with all areas of the ventricles recovering simultaneously
68
What on an ECG represents ventricular repolarization?
ST segment and T wave
69
Why is there no visual representation of atrial repolarization on an ECG?
It is obscured by the QRS complex
70
What is a refractory period?
Recovery period where myocardial cells are unable to be electrically stimulated (from phase 0 - phase 3, or QRS to the top of the T wave)
71
At what point in the electrical cycle is the cell able to be depolarized again?
Phase 3/halfway down the downslope of the T wave
72
What is the isoelectric line on an ECG?
Represents no current flow in the heart
73
What is seen on an ECG if electrical current flow is parallel to the lead axis with the current moving toward the positive pole?
Monophasic positive deflection
74
If the electrical current is parallel to the lead axis but the current is moving toward the negative pole what will the visual result on an ECG?
Monophasic negative deflection
75
If the electrical current is moving perpendicularly to the lead axis and moving toward neither the positive or negative pole what is the visual result on an ECG?
Biphasic deflection
76
Which leads result in larger deflection amplitude?
Parallel leads \> perpendicular leads
77
What are two conditions that can affect the magnitude of electrical current?
MI may decrease the amplitude, hypertrophy increases amplitude
78
What is the axis of lead I?
From RA to LA
79
What is the axis of lead II?
From RA to LL
80
What is the axis of lead III?
From LA to LL
81
What is a QS wave?
Totally negative deflection with no R wave present (not normal)
82
What are the unipolar limb leads?
aVR, aVL, aVF
83
How are unipolar limb leads defined?
Consist of only one positive electrode, connected to a common central terminal, other end of the axis is at the center of the electrical field/approximate center of the heart
84
Where should lead V1 be placed?
4th ICS R of sternum
85
Where should V2 be placed?
4th ICS just L of sternum
86
Where should V3 be placed?
Midway between V2 and V4
87
Where should V4 be placed?
5th ICS in the L MCL
88
Where should lead V5 be placed?
Horizontal to v4 in the L AAL
89
Where should V6 be placed?
Horizontal to V4 in the L MAL
90
Why should limb leads be placed on the trunk rather than the limbs during continuous ECG monitoring?
To minimize artifact from patient motion
91
What color is the L arm electrode?
Black
92
What color is the R arm electrode?
White
93
What color is the L leg electrode?
Red
94
What color is the R leg electrode?
Green
95
What color are the precordial electrodes?
Brown
96
What electrodes is MCL 1 composed of?
RA placed on the L shoulder just below the clavicle, LA placed on the R shoulder just below the clavicle, LL when placed at the 4th ICS just R of the sternal border
97
What does lead MCL 1 show?
Right sided view of the heart allowing for differentiation between RBBB and LBBB, L PVCs from R PVCs, R VT from L VT, and supraventricular beats from ventricular escape beats
98
What is MCL 6?
Modfied bipolar chest lead approximating V6 and provides a left sided view of the cardiac electrical activity and does the same things as MCL1
99
What electrodes make up the MCL 6 lead?
RA/white placed on the L shoulder just below the clavicle, LA/black placed on the R shoulder just below the clavicle, LL/red when placed horizontal to the to the 5th ICS in the L mid-axillary line
100
what are the possible morphologies of the P wave?
Positive, negative, or biphasic depending on lead
101
Define the PR segment?
Isoelectric line from the end of the P wave to the beginning of the QRS complex representing the electrical impulse traveling through the AV node where it is delayed and then through the ventricular conduction system prior to ventricular depolarization
102
Define PR interval
End of the P wave to the beginning of the QRS complex (typically 0.12-0.2 seconds in duration)
103
What is the QRS complex?
Represents time required for ventricles to depolarize, from the end of the PR segment to the J point, usually 0.04-0.10 seconds
104
What does the ST segment represent?
Early ventricular repolarization, corresponding to phases 1 & 2 of the action potential
105
What affects the length of the ST segment?
HR changes, medications, electrolyte disturbances
106
What is an abnormal deviation of the ST segment from the isoelectric line?
Elevation greater than 1 mm or depression greater than 0.5 mm in relation to TP segment or PR segment when measured at a point 2 mm beyond the J point
107
What are ST elevation changes typically caused by?
Myocardial ischemia/injury, conduction abnormalities, medication
108
What does the T wave represent?
Ventricular repolarization, typically has a positive deflection and is rounded and slightly asymmetrical
109
What affects T wave morphology?
MI, potassium or calcium, medications, ANS effects
110
What does a U wave represent?
Potentially slow repolarization of purkinje fibers
111
What characteristics make up a U wave?
Follows T wave, same polarity as T wave but smaller, most common in V3, abnormal prominence suggests electrolyte abnormality or other disturbance
112
What causes changes in the length of the QT interval?
Age, sex, changes in HR (slower HR = longer, faster HR = shorter), medications, prinzmetal's angina, SAH; typical length is 0.32-0.40 for a HR between 60-95
113
What can a prolonged QT interval lead to?
Torsades de Pointes
114
What are the characteristics of the TP segment?
Isoelectric, follows T or U wave, shortens as HR increases and lengthens as HR decreases
115
What is the measurement of each small box on an ECG?
1 mm x 1 mm
116
What is the time measurement of each small block on an ECG?
0.04 s
117
What is the time measurement of each large block on an ECG?
0.2 seconds
118
How many large blocks equal one second on an ECG?
5
119
What is the voltage equivalent of one small block on an ECG?
0.1 mV (1 mm)
120
What should each P wave be inspected for?
Morphology, P before every QRS?, regular P-P interval, atrial rate
121
What characteristics should each QRS complex be analyzed for?
Morphology, R-R interval regular?, ventricular rate
122
Which leads is the QT interval longer in?
V2 and V3
123
How is the QT interval measured?
Measure the lead with the tallest T waves or in an irregular rhythm the QT interval that follows the longest R-R interval, do not include the U wave if present
124
What is the rule of thumb for a measured QT interval?
For heart rates 60-100 bpm, a normal QT interval does not exceed half the R-R interval
125
What is a QTc?
QT corrected for a HR of 60 bpm using Bazett's formula (QT interval/the square root of the R-R interval)
126
True or false, the QT interval is not affected by HR in post menopausal women or gender in children.
True
127
What are the criteria for a sinus arrhythmia and what is it the result of?
Changes in intrathoracic pressure during breathing; irregular rhythm with the shortest P-P and R-R intervals varying by at least 0.12s from the longest P-P and R-R intervals, rate may be normal or \< 60, QT interval varies with HR but all other measurements are normal
128
What are the characteristics of tachydysrhythmias?
HR \> 100 bpm; Shortenes diastolic time and coronary perfusion time, initially increases CO but eventually results in decreased CO and BP d/t decreased stroke volume, decreases aortic pressure, increases the work of the heart
129
What are the characteristics of a bradydysrhythmia?
HR \< 60 bpm; diastole is prolonged resulting in adequate coronary perfusion time but may decrease if HR is too slow, reduced MVO2 (work of the heart)
130
What are the characteristics of premature complexes?
Occur early d/t ectopy and are followed by a pause; characteristically bigeminy, trigeminy, or quadrigeminy
131
What are the characteristics of an escape complex or rhythm?
Occurs after a pause and serves as a latent pacemaker, originates from the AV node, junctional tissue, or ventricular tissue, stop when SA node regains function
132
What are the criteria of a BBB?
Rhythm usually regular, ventricular and atrial rates usually equal, consistent P wave morphology with a P wave before every QRS, normal or prolonged PR interval, QRS usually wide (0.12-0.14s) and is constant or has slight variation, ST-T in the opposite direction to the QRS
133
What is the normal ECG configuration of lead I?
Positive P wave, small q with R\>S, positive T wave, isoelectric ST segment
134
What is the normal ECG configuration of lead II?
Positive P wave, small q and R\>S, positive T wave, isoelectric ST segment
135
What is the normal ECG configuration of lead III?
Variable P wave, small or absent q with R\>S, variable T wave, isoelectric ST segment
136
What is the normal ECG configuration for lead aVR?
Negative P wave, small/absent/large Q with small/absent r and a large S that may be a QS, variable T wave, and isoelectric ST segment
137
What is the normal ECG configuration for lead aVL?
Variable P wave, small/absent/large Q with small/absent/large R and absent or large S, variable T wave, and isoelectric ST segment
138
What is the normal ECG configuration of lead aVF?
Positive P wave, small/absent q with small/absent/large R and absent to large S, variable T wave, isoelectric ST segment
139
What is the normal ECG configuration of lead V1?
Variable P wave, absent Q, absent/small r, R
140
What is the normal ECG configuration of lead V2?
Variable P wave, QRS same as V1 with the R\>R in V1, variable T wave, isoelectric ST segment
141
What is the normal ECG configuration of lead V3?
Variable P wave, small/absent q, R\>/=S, R\>R in V2, positive T wave, isoelectric ST segment
142
What is the normal ECG configuration of lead V4?
Positive P wave, small/absent q, R\>S, R\>R in V3, positive T wave, isoelectric ST segment
143
What is the normal ECG configuration of lead V5?
Positive P wave, small q, large R (\<26 mm), R\>R in V4, S
144
What is the normal ECG configuration of lead V6?
Positive P wave, small q, large R (\<26 mm), S
145
What are the normal measurements of a P wave?
Measures 0.08-0.11 seconds in width, \<2.5 mm in amplitude
146
What are the normal measurements of the Q wave?
Typically \<0.04s in duration, depth no more than 2mm in leads I/II/aVL/aVF/V4-6, depth 2-6mm in lead III, large Q in aVR, absent in leads V1-V3
147
What are the criteria for a pathological Q wave?
\>0.04s in duration, 1/3 the height of QRS amplitude, \>25% of R wave amplitude in leads I/II/III/aVF, \>15% of R wave amplitude in leads V4-V6, \>50% of R wave amplitude in lead aVL; new Q waves are typically associated with the loss of R waves in the same leads
148
What constitutes a pathological ST segment?
Elevation \>1mm above isoelectric in \>/= 2 contiguous leads, depression \>0.5-1mm below isoelectric in \>/= 2 contiguous leads, convex or coved ST elevation indicative of AMI, concave ST elevation indicative of pericarditis, upsloped ST depression considered non-specific but may indicate CAD, horizontal or downsloping ST depression is significant for UA or NSTEMI
149
What are the normal characteristics of a T wave?
Does not exceed 5mm in limb leads and 10 mm in precordial leads, upstroke longer than downstroke, positive in leads I/II/V3-6, variable in leads III/aVL/aVF/V1-V2, and negative in aVR
150
What are the characteristic findings in myocardial ischemia and NSTEMI?
Symmetrical T wave inversion, ST depression
151
What is typical of myocardial injury?
Convex ST elevation
152
What is typical of myocardial infarction/STEMI?
Pathological Q waves
153
What is the difference between subendocardial ischemia and transmural injury?
Subendocardial ischemia causes ST depression because the repolarization is still occurring in the usual direction but is then delayed at the area of injury, transmural injury causes completely altered repolarization in which the electrical activity is still moving in the direction of the epicardium
154
What are the stages of infarction?
Normal -\> ischemia -\> injury -\> infarction
155
True or false, early repolarization is a normal variant in young adults.
True, this causes ST elevation
156
What measurements of ST elevation are pathological in limb leads vs precoridal leads?
1mm in limb leads, 2mm in precordial leads
157
List the primary causes of ST elevation
Ventricular aneurysm, pulmonary embolism, intracranial hemorrhage, acute MI, early repolarization, pericarditis
158
What are the primary causes of ST depression?
Myocardial ischemia, LVH, intraventricular conduction defects, medication (Digoxin), reciprocal changes in leads opposite the area of acute injury, unstable angina
159
What are the typical findings of a posterior MI?
Tall R waves and ST segment depression in leads V1-V4 (apply leads V8-9 for definitive diagnosis), may also have tall T waves, associated with lateral and inferior MIs
160
What are the steps to ECG analysis?
Rate, rhythm, P waves, QRS complex, PR interval, QRS duration, QT interval, determine QTc (\>0.44 associated with 8x risk CVS mortality)
161
What are the criteria for WPW syndrome?
Rate dependent on underlying rhythm, regular rhythm unless associated with afib, normal p waves unless afib present, short PR interval, wide QRS with delta wave present
162
What are the criteria for PAC's?
Rate nonspecific, rhythm irregular, P waves present but may be morphologically different in PAC, variable PR interval in the PAC but normal otherwise, normal QRS
163
What are the criteria for atrial tachycardia?
Rate 150-250 bpm, regular rhythm, normal P waves but differ in shape from normal sinus P waves, PR interval may be short, normal QRS interval
164
What are the criteria of a supraventricular tachycardia?
Rate 150-250, regular rhythm, P waves often buried in proceeding T waves, usually not possible to measure PR interval, normal QRS unless conducted through ventricles abnormally
165
What are the criteria for a paroxysmal supraventricular tachycardia?
Rate 150-250, irregular rhythm, P waves frequently buried in preceding T wave, usually cannot measure PR interval, normal QRS but may be wide if abnormally conducted through the ventricles
166
What are the criteria for atrial flutter?
Atrial rate of 250-350, ventricular rate is variable, atrial rhythm regular, ventricular rhythm variable, P waves saw-toothed, variable PR interval, QRS usually normal but may look wider if flutter waves are buried inside of it
167
What are the criteria for atrial fibrillation?
Atrial rate of 350 per minute or greater, ventricular rate variable, irregular rhythm, no true P waves only chaotic electrical activity, no PR interval, normal QRS
168
What are the criteria for a premature junctional contraction?
Rate variable, rhythm irregular, no P wave or retrograde P wave, no PR interval, normal QRS
169
What are the criteria for an accelerated junctional rhythm?
Rate 61-100, rhythm regular, buried or retrograde P waves, no PR interval, normal QRS
170
What are the criteria for a junctional tachycardia?
Rate 101-180, rhythm regular, buried or retrograde P waves, no PR interval, normal QRS
171
Criteria for a junctional escape rhythm
Rate \<60, rhythm regular, buried or retrograde P waves, no PR interval, normal QRS
172
Define bigeminy
Ectopy every other beat
173
Define trigeminy
Ectopy every third beat
174
Define quadrigeminy
Ectopy every fourth beat
175
Criteria for monomorphic ventricular tachycardia
Rate 100-250, rhythm regular, no P waves or not associated with the QRS complex, no PR interval, wide QRS
176
criteria for polymorphic ventricular tachycardia
Rate 100-250, regular or irregular, no P wave or not associate with the QRS complex, no PR interval, wide QRS
177
Criteria for ventricular fibrillation
Indeterminate rate, chaotic rhythm, no P waves, no PR interval, no QRS
178
Criteria for first degree AV block
Rate dependent on underlying rhythm, regular rhythm, normal P waves, prolonged PR interval, normal QRS complex
179
Criteria for a second degree AV block type I (Wenckebach)
Rate dependent on underlying rhythm, regular atrial rhythm, irregular ventricular rhythm, normal P waves but more P waves than QRS complexes, progressively longer PR interval until one P wave is blocked and the QRS is dropped, normal QRS
180
Criteria for a second degree AV block type II (mobitz II)
Atrial rate usually between 60-100, slower ventricular rate, regular atrial rhythm, regular or irregular ventricular rate, PR interval normal or prolonged but constant, QRS may be normal but is usually wide
181
Criteria for third degree AV block
Atrial rate 60-100, ventricular rate 40-60 (slower than atrial rate), usually a regular rhythm with independent atria and ventricles, normal P waves but more than QRS complexes, PR interval varies greatly, normal or wide QRS
182
BBB Criteria
Usually regular rhythm, any rate but equal atrial and ventricular, normal or prolonged PR interval, wide QRS, ST-T in opposite direction to terminal portion of QRS complex
183
RBBB QRS Morphology
V1: rSR' with the R rabbit ear taller than the L, VAT \>0.02 s, inverted T wave; V6: qRS with large broad S wave also seen in leads I and aVL, normal VAT, upright T wave
184
RBBB Criteria
QRS \>0.10s, normal or R axis deviation, broad S in leads I/aVL/V5/V6, RSR' in lead V1 with R' taller than R, qRS pattern in V5 and V6, ST-T opposite of terminal portion of QRS
185
RBBB etiologies
Normal variant, congenital heart disease, RVH with pulmonic stenosis or pHTN, acute dilation of the R ventricle, coronary insufficiency, degenerative disease in conduction system
186
LBBB QRS Morphology
V1: negative complex with QS or rS with deep/wide S sharply downsloping, normal VAT, upright T; V6: positive complex with R or M complex and absent septal q wave, VAT markedly delayed, T wave inverted
187
LBBB Criteria
wide QRS (\>0.10), QRS predominantly negative in leads V1 and V2, predominantly positive in V5 and V6 and often notched, absence of small q waves in leads I/aVL/V5/V6, wide monophasic R waves in I/aVL/V1/V5/V6
188
LBBB etiologies
MC organic heart disease (HTN, ASCVD), anterior MI, valvular disease (AS, etc), rheumatic heart disease, cardiomyopathy, HF, LVH, coronary insufficiency, trauma, cardiac tumors, fibrosis of conduction system
189
What are the ECG features of LVH?
Tall R waves in L ventricular leads, deep S waves in R ventricular leads, delayed intrinsiciod deflection in V6 (time from QRS onset to peak R is \>/= 0.05sec), widened QRS/T angle (L ventricular strain pattern or ST-T oriented opposite to QRS direction), L shift in frontal plane QRS axis, evidence of L atrial enlargement
190
What are the Estes criteria for LVH?
Diagnostic requires 5 points, probable requires 4 points: R or S in limb leads \>/= 20 mm (3 points) S in V1 or V2 \>/= 30 mm (3 points) R in V5 or V6 \>/= 30 mm (3 points) ST-T abnormalities with Digitalis (3 points) ST-T abnormalities without Digitalis (1 point) Left atrial enlargement in V1 (3 points) Left axis deviation (2 points) QRS duration 0.09 seconds (1 point) Delayed intrinsicoid deflection V5 or V6 (\>0.05s) (1 point)
191
What are the Cornell Voltage criteria for LVH?
Sensitivity of 22%, specificity of 95% S in V3 + R in aVL \> 24mm (men) S in V3 + R in aVL \> 20 mm (women)
192
What are the limb lead voltage criteria for LVH?
R in aVL \>/= 11 mm If LAD, R in aVL \>/= 13 mm plus S in III \>/= 15 mm R in lead I + S in lead III \> 25 mm
193
What are the chest lead criteria for LVH?
S in V1 + R in V5 or V6 \>/= 35 mm
194
What are the common diagnostic criteria for RVH?
R in V1 \>/= 0.7mV QR in V1 R/S in V1 \>1 with R \>0.5mV R/S in V5 or V6 \>0.7mV R in V5 or V6 \>/=0.4mV with S in V1 \>/= 0.2mV RAD \>/= 90 degrees S1Q3 pattern S1S2S3 pattern P pulmonale
195
What must there be at least one of in the presence of a narrow QRS for the diagnosis of RVH?
RAD greater than 90 degrees in the presence of a disease capable of causing RVH, R in aVR \>/= 5mm, R in aVR \> Q in aVR
196
What are the specific features of RVH found in lead V1?
R/S ratio \> 1 and negative T wave, qR pattern, R \> 6 mm OR S \<2mm OR rSR' with R' \>10mm
197
What are chest lead criteria for RVH?
R in V1 + S in V5 or V6 10mm R/S ratio in V5 or V6 \<1 R in V5 or V6 \< 5mm S in V5 V6 \> 7mm \*ST segment depression and T wave inversion in R precordial leads is usually seen in severe RVH such as in pulmonary stenosis and pulmonary hypertension
198
What is the simplified ECG criteria for RVH?
V1-2: R taller than S, strain pattern V5-6: deep S wave, no strain pattern RAD \*strain pattern denotes a change in repolarization shown by a downward sagging ST segment with inverted T wave when seen in any lead with a tall R wave (leads III, aVF, V1-2)
199
What is the simplified ECG criteria for LVH?
V1-2: deep S wave, no strain pattern V5-6: tall R wave, strain pattern, also in leads I and aVL \*sum of S in V1 or V2 + R in V5 or V6 = 35 mm or more LAD
200
What does RVH commonly result from?
COPD, pulmonic stenosis, and systemic hypertension
201
What does LVH typically result from?
Chronic systemic HTN, AS \*increased risk for MI and/or SCD, more likely to have ventricular ectopy which additionally may be difficult or impossible to suppress with medication
202
What are the characteristics of a normal Q wave?
Generally \<0.04s in duration Depth \< 2mm in leads I, II, aVL, aVF, V4-6 Depth 2-6mm in lead III Large Q in aVR Absent Q in leads V1-3
