Flashcards in Diagnostic Features of the EKG Deck (49):
Qtc = QT/ sqrt(RR)
Cause of the P wave
Cause of the PR interval
index of conduction time across the AV node
PR Interval Length
0.12 - 0.20 seconds
Less than 0.44 s
Light Lines on EKG represent what amount of time?
Heavy Lines on EKG represent what amount of time?
Heart Rate Equation from EKG
HR = 300 / # heavy lines between 2 QRS's OR HR = 1500 / # mm between 2 QRS's
Positive Deflection results from?
Depolarization moving towards a positive electrode
QRS will be upwards in which leads?
Left and Lateral Leads
QRS will be downwards in which leads?
# of Bipolar Leads and Locations?
3 Total. I, II, III. They are located on the right and left arms, and the left foot/leg.
Lead II direction of positivity?
Right hand (negative) towards left foot (positive)
Lead I direction of positivity?
Right hand (negative) towards left hand (positive)
Lead III direction of positivity?
Left hand (negative) towards left foot (positive)
Augmented Limb Leads?
aVR (augmented right hand), aVL (left hand), and aVF (left foot)
V1 - V6.
aVR Deflection Direction? Positive, Negative or both?
Directionality from heart towards RAISED right hand produces a completely negative EKG. (p, qrs and t all negative)
II, III and AVF are all referred to as...?
Inferior Leads. Give information about the inferior wall of the heart. Damage to this region would best be seen in these leads.
I and AVL are referred to as....?
Lateral Leads. Lateral infarcts in the upper/higher portion of the left ventricle would be seen here.
Note: Almost all infarcts occur in the left ventricle.
This means you, Soliman.
Right Sternal Border. Near SA node. Shows right ventricular Abnormalities and septum.
Left Sternal Border. Also looking at right side of the heart. Shows right ventricular Abnormalities and septum.
Left Sternal Border below V2. Shows septal defects and a portion of the left ventricular free wall.
Below Pec Major in 4th intercostal space. Shows septal defects and a portion of the left ventricular free wall.
Placed Lateral to V5 in 4th intercostal space. Left ventricular lead.
What is the plane of the precordial leads?
Horizontal Plane. Take a "slice" of the heart.
Below Pec Major in 4th intercostal space. Exclusively left ventricular lead.
Ventricular Hypertrophy EKG
Increased Volts/Amplitude of QRS complex in certain leads.
Left Ventricular Hypertrophy Leads
Big R Waves in left sided leads (I, aVL, V5 and V6)
Right Ventricular Hypertrophy Leads
Big R Waves in right sided leads (V1 and V2)
Insufficient blood supply to meet demands (in the ventricles)
Ischemia EKG Effects
-Depression of the ST segment (Due to inc O2 demand in face of fixed coronary obstruction)
-T Wave Inversion (due to acute coronary artery obstruction during low O2 demand)
ST elevation is usually due to...?
Current Transmural Injury (Infarction)
Sign of Past Infarction?
Q wave on a completely R positive lead.
Significant Q Wave Definition
1) Greater than 1/4 the amplitude of the R wave
2) One small box wide (0.04 seconds)
3) Seen in usually at least 2 leads reflecting the same region of the left ventricle.
Transmural Myocardial Infarct Progression on EKG
1) Peaked T-Wave (rare and short)
2) T-Wave Inversion (no damage yet)
3) ST Elevation (injury has occurred)
4) Q-Wave, ST-Elevation, T-Inversion (seen all together- too late!)
Subendocardial Infarct causes what on the EKG?
ST Depression... NO Q WAVE!
Infarct Location if seen in V1-V2?
Infarct in Anterospetal Wall
Infarct Location if seen in V3-V4?
Infarct in Anterior Wall
Infarct Location if seen in V5-V6?
Infarct in Anterolateral Wall
Infarct Location if seen in II, III, aVF?
Infarct in Inferior Wall
Infarct Location if seen in I, aVL?
Infarct in High Lateral Wall
Prolonged QT interval Definition
QT Interval is longer than half of the R-R interval
Causes of Long QT
Hypocalcemia, hypokalemia, hypomagnesemia
Class 1A or 3 Anti-arrhythmic Drugs
Congenital Long QT Syndrome
Flattened T Wave with Presence of merging with U wave. Long QT interval!
Shortened QT interval!
Hyperkalemia EKG (3 stages)
5.5-7.5 (mmol/L) - Tall T Waves (peaked and symmetrical)
7.5-9.0- P&R waves flatten, QRS&T broaden and big S Waves develop
9.0+ - P&R waves gone, S&T Waves Broaden in a sine wave pattern