12 Lead EKGs Flashcards
Current moving toward the positive pole will produce a
positive deflection on the EKG
Current moving toward the negative pole will produce a
negative deflection on the EKG
A lead that has a negative pole and a positive pole is
a bipolar lead
Unipolar leads
utilize the center of the heart as the negative point and the lead is the positive pole.
When the current is flowing perpendicular to the lead, it produces what kind of wave?
biphasic.
What leads are in the heart’s frontal plane and what kind of electrode are they
Leads I, II, III, aVR. aVL, and aVF.
Bipolar
What leads are in the heart’s horizontal plane and what kind of electrode are they
V1, V2, V3, V4, V5, V6.
Unipolar
What is Eintoven’s Triangle
Its made up by leads I, II, and III. (Rule of Ls)
What are the Augmented Limb Leads
aVR, aVL, and aVF.
aV stands for augmented vector.
What is the systematic approach to reading EKGs
- ) Rate
- ) Rhythm
- ) Axis
- ) Intervals
- ) Morphology
What is the Axis looking at?
The overall direction of electrical conduction through the heart.
What is the normal axis?
-30 degrees (aVL) to 90 degrees (aVF). (downward and leftward).
Abnormal axis suggests what?
A change in shape or orientation of the heart, or a defect in the conduction system that causes the ventricles to depolarize in an abnormal way.
If I and aVF have positive deflections of a QRS it is a
normal axis
If I and aVF do not have positive deflections, what do you do to determine axis?
Look at the most isoelectric/eqiphasic lead, and the axis is perpendicular to that lead.
In the rule of thumbs, which lead is which
Left thumb is lead I
Right thumb is lead aVF
Left axis deviation can mean what?
Left anterior fascicular block LBBB LV hypertrophy Inferior MI Ventricular Ectopy Paced rhythm WPW
Right axis deviation can mean what?
Can be normal Left posterior fascicular block Lateral MI RV Hypertrophy Acute lung disease (PE) Chronic lung disease (COPD) Ventricular ectopy Hyperkalemia Na channel blocker toxicity WPW
P wave can be biphasic in which lead?
V1
T wave should always be what direction
Should always be upright.
What shows right atrial enlargement?
Peaked P wave in V1 or inferior leads.
Greater than 1.5 mm in V1
Greater than 2.5 mm in II
What is the most common cause of right atrial enlargement?
Pulmonary hypertension
Left atrial enlargement
Wider terminal negative portion of the P wave in V1, at least 0.04
Notched wide P waves in inferior leads (II, 0.12 seconds long)
Biatrial enlargement
Peaked and broad Ps in the inferior leads, at least 2.5 mm tall and 0.12 s wide.
V1 is broad and biphasic with terminal negative deflection at least 1mm deep and 0.04 seconds wide.
If a QRS complex is longer than 0.12 seconds there is what present and what lead do you have to look at.
a complete bundle branch block
V1
If Q wave is larger than 2mm
pathologic finding of old MI.
If the QRS duration is 0.1 to 0.12 seconds, what is most likely going on?
an incomplete bundle branch block.
In a right bundle branch block, what should you see on an EKG
V1 will be upright
V1-V2 will have “bunny ears” (rSR’)
What are the two R peaks in a right bundle branch block
r is the LV depolarizing
R’ is the RV depolarizing
Frequently, the axis deviation will be in which direction of the bundle block?
The same direction
If the patient has a left bundle branch block, what can you not do
You cannot reliably evaluate for an ST elevation.
The ST segment represents what?
The time between ventricular depolarization and repolarization.
ST elevation in one spot represents what?
an acute myocardial infarction (STEMI)
Diffuse ST elevation represents what?
Pericarditis
ST depression represents what?
myocardial ischemia
What are the symptoms of a STEMI for males
chest pain, SOB, diaphoresis, L arm or jaw pain, back pain between shoulder blades.
May present with syncope, CHR, stroke, or shock.
What are the symptoms of a STEMI for females
vague, generally feeling poor, indigestion, heart burn, jaw or back pain, nausea.
More likely to be diabetic. May present with CHR, stroke, syncope, or shock.
What is a STEMI a result of?
An occlusive coronary thrombus at the site of a preexisting atherosclerotic plaque.
Treatment of a STEMI
ASA/ plavix loading
immediate angiography and percutaneous intervention. (if not available, thrombolytics).
Also morphine, beta blockers, and nitrates.
How does the EKG evolve with a STEMI
develop Q waves that can be permanent.
T waves are inverted.
The T wave should always be what direction
Upward
If negative or inverted, suggests ischemia or evolving MI.
If T waves are peaked, what does it mean?
Hyperkalemia
Long QT syndrome
QT segment is longer than 0.48 and they aren’t on QT prolonging meds. Congenital. need genetic testing.
What are the sudden cardiac death causes
Long QT syndrome
Brugada
ARVD
Brugada syndrome
genetic condition causing RBBB with ST elevation in V1-V3. Need genetic testing.
Arrhythmogenic Right Ventricular Displasia ARVD
RV myocardium replaced by fibrous and fatty tissue. Leads to VT/SCD of RV origin. Need an MRI to diagnose.
Symptoms of SCD
Syncope due to VF or sudden death.
What is left ventricular hypertrophy?
thickening of the myocardium in the left ventricle.
What causes left ventricular hypertrophy?
HTN
Left ventricular hypertrophy
Large QRS spikes because lots of voltage in the thickened muscle.
Someone with hypertrophy also needs a cardiac echo. Why?
EKG is insensitive and not reliable. Needs an echo to measure the thickness of the septum.
What are the two common pacemaker leads and what do they cause?
RA lead causing the “normal” P wave.
RV lead causes a LBBB. (originating from the RV)
What may you see on a strip with a pacemaker
pacing spikes.
What level is potassium to result in peaked T waves
5.5. As the level rises, the conduction system slows, atria first, then ventricles: loss of P waves and then a new BBB and then bradycardia leading to asystole.
Hypokalemia
Prolonged QT interval
ST depression
T wave inversion
Sometimes large U waves
Hypercalcemia
Shortened QTcinterval
Hypocalcemia
Prolonged ST segment and QTc
Hypomagnesia
Prolonged QT interval
Hypermagnesia
Prolonged AV conduction, eventual heart block.
What is the classic EKG finding for pericarditis
diffuse ST elevation and PR depression.
Symptoms of pericarditis
Pleuritic chest pain, relieved by sitting forward, may have preceding viral syndrome, fever, pericardial rub on exam. SOB
Treatment for pericarditis
Anti-inflammatories
Possibly drain the effusion.
WPW
Short PR interval
Delta waves
Widened QRS
What happens in the WPW
Direct connection to the ventricle through bundle of Kent
What is the one instance when WPW can be fatal
If there is a bundle of Kent because it can cause Afib.
Symptoms of WPW syndrome
palpitations
syncope
near syncopy
(Ablation of accessory pathway is indicated).
What happens in a PE
most commonly caused by an embolus from the deep venous circulation to the pulmonary artery.
Risk factors for DVT
Virchow’s triad:
Venous stasis, injury to a vessel wall, and hyper coagulability.
Symptoms of a PE
Dyspnea, tachycardia, Hypoxia, tachypnea, pleuritic chest pain, can be vague.
PE
Sinus tachycardia
S1Q3T3 abnormalities
How do you diagnose a PE
CT scan with contrast (pulmonary artery CT angiography)
Treatment for PE
anticoagulation, may require thrombolytic therapy.