Normal EKG Flashcards
What is normal heart rate?
Normal for SA node= 60-100 bpm
What are all of the leads on a 12 lead EKG?
Lead I: right arm (-), left arm (+) Lead II: right arm (-), left leg (+) Lead III: left arm (-), left leg (+) avR: right arm (+) avL: left arm (+) avF: feet (+) Precordial leads V1-V6: all of these should be (+), takes snapshot of the heart
What leads correspond to which sections of the heart?
Lateral: I, aVL, V5, V6
Anterior: V3, V4
Septal: V1, V2
Inferior: II, III, aVF
What are basics of EKG paper?
Vertical axis= amplitude
1mm per square so one box= 5 mm
Horizontal axis= time
1mm=0.04 sec so 1 box= 0.2 sec
Easiest way to think of it is that each box is a 5x5
What is axis deviation and where can we see it at?
Average direction of depolarization as impulse travels through ventricles.
Axis refers to the direction of depolarization of QRS complex.
Examine leads: I, II, III AND aVR, aVF, aVL
DONT USE PRECORDIAL LEADS TO LOOK AT AXIS DEVIATION
Sandy tells us to look at limb lead I and aVF to calculate it
What are values for axis deviation?
Normal: between -30 and +90
Left axis: more negative than -30
Right axis: more positive than 90
What are some causes for extreme axis?
Emphysema Hyperkalemia Lead transposition Artificial cardiac pacing V tach
What are causes of right axis deviation?
Normal finding in kids and tall thin adults RVH Chronic lung disease Anterolateral MI Left posterior hemiblock Pulmonary embolus Atrial septal defect Ventricular septal defect
What are causes of left axis deviation?
Left anterior hemiblock Q waves of inferior MI Artificial cardiac pacing Emphysema Hyperkalemia
What is difference between an interval and a segment?
Interval always has a wave form associated with it.
Segment is usually isoelectric
T/F: if there is a p wave for every QRS and they are in same direction it is considered sinus rhythm?
True
What are characteristics of P wave and what is normal amplitude?
Represents depolarization of atrial myocardium.
Normal= not wider than 3 little boxes (0.11 sec) and not talker than 3 mm, not notched or peaked
What does the P wave look like on the different leads?
Positive and rounded in I, II, aVF
Upright in V4-V6
Negative in aVR
Positive, negative, or biphasic in leads III, aVL, V1-V3
What are characteristics of PR interval?
Represents atrial depolarization plus normal delay at AV node (to optimize filling)
Normal: 0.12-0.20 sec/no longer than one large box
What are characteristics of PR segment?
Should be isoelectric
Can be elevated with atrial infarction or pericarditis
What are characteristics of QRS complex? Normal characteristics?
Represents depolarization of ventricular myocardium
Normal width= 0.07-0.11 sec (best to look at I and V1)
Normal amplitude= no smaller than 6mm in I, II, III and no taller than 25-30 mm in precordial leads
What are normal characteristics of Q wave?
Represent septal depolarization and must be distinguished between pathological Q waves which indicate a MI.
Normal: present only in leads I, aVL, V5, V6; small in leads aVF and V5 (normal variant)
Normal width= 0.04 sec (one tiny box)
Normal amplitude= not deeper than 1/3 of QRS complex
What are characteristics of ST segment?
Represents time when ventricle cells are in plateau phase, and when ventricles are in absolute refractory period and will not response to stimulation.
Should be isoelectric.
What causes ST elevation?
Vessel occlusion
T/F: ST deviation and T wave abnormalities are seen with MI.
True
What are characteristics of T waves?
Represent repolarization of ventricles.
Should have same polarity as QRS complex.
T waves are very fickle and not as reliable as ST depression or elevation in dx of ischemia.
