Microsoft word - 12 and 15 lead ecg interpretation

12 and 15 lead ECG Interpretation
Lead Placement: even if you are not performing the test itself, knowledge of the correct lead
placement is useful in troubleshooting an ECG test.
V2 : feel for the space between the left clavicle and the rib beneath, place your baby finger there and feel down with
subsequent fingers until your index is resting on the 4th rib space (4th intercostal space, left sternal border)
V1 : place this lead directly across from V2 on the right side of the sternum (4th intercostal space, right sternal
border)
V4 : feel for the midway point of the left clavicle and then come straight down to the rib space beneath V1’s level
(midclavicular 5th intercostal space)
V3 : midway between V2 and V4 on a curve
V6 : feel straight down below the armpit to the same rib space that V4 sits on; “where a woman’s bra would sit”
(mid-axillary 5th intercostal space)
V5 : midway between V4 and V6 on the same plane/rib space (anterior axillary 5th intercostal space)
Breast/Adipose Tissue: move soft tissue aside, if possible, to place leads close to chest wall. Otherwise, if the
correct placement will be compromised – place the lead on the tissue directly above the correct landmark.
Ground/limb/reference leads: place at your discretion, leg leads can occupy the same limb (ie: amputee,
cellulitis), or lowest part of the trunk.
The QRS Complex: brief explanation of what is normal and what is not. (Note: on the 12 lead
paper; 1 tiny square=.04 sec and 1 big square=.20sec)
P wave: initiated by the sinus node, if it is not present then the beat is being paced from another area
(accessory/abhorrent pathway)
PR interval: time it takes the sinus beat to be transmitted to the AV node (normally .12-.20 sec or 3-5 tiny squares),
measured from the beginning of the P wave to the beginning of the R wave
Q wave: negative deflection just prior to R spike, may be subtle or absent. Appears 4-6 hours after an infarct, may
represent old damage but treat as new tissue insult if patient has symptoms and has ST changes
Pathological Q wave: the negative wave depth is more than 1/3 the height of the positive R wave, denotes tissue
death – old or current
R wave: any positive spike in the main body of the QRS, tall R denotes ventricular hypertrophy
QRS: normally .12 sec or less, otherwise considered a wide QRS which indicates a Bundle Branch Block (hides
acute changes, may permanently change the T)
S wave: negative deflection just after the R spike, may be subtle or absent
ST interval: measured from where the S wave is ending (returning to baseline/neutral) to the end of the T wave
T wave: positive wave after the QRS
QT interval: measured from the start of the Q wave to the end of the T wave, should be ½ of the R-R interval
(*MANY COMMON DRUGS CAN PROLONG*)
R wave progression: normal phenomenon where in leads V1-V4 the S wave prominence gradually gives rise to
R wave being prominent, if not – denotes infarct
-no progression = Q wave MI (ie: if the R is difficult to see, the deflection is not an S wave but a Q wave = infarct) -poor progression = smaller MI (ie: R is small/subtle and increases slightly as you move through to V4) R-R interval: the measurement of the distant from one R spike to the next
R on T phenomenon: if the QT interval is prolonged ie:> ½ R-R interval (*MANY COMMON DRUGS CAN
PROLONG) then a T wave and R wave may occur simultaneously causing Torsades de Pointes
T elevation: means complete occlusion, Q wave will appear, needs thrombolytics
T depression: means partial or impending occlusion, ACS is termed, T may elevate, treat also.
Basic Lead groups: T changes(inversion) or elevation/depression in ST segment
Inferior Wall - leads II, III, aVF (* 45-55% of Inferior Infarcts affect the Right Ventricle, VERIFY WITH 15 LEAD) NOT AS CLINICALLY SIGNIFICANT: aVR (Q inverted, T inverted) Blood work: most useful ~ 4 hours post infarct, pericarditis or myocarditis will not cause
increase in these levels
Myoglobin: earliest to spike, false positives more likely (MVA, trauma, ARF) Troponin: small changes even with angina, stays elevated > week after damage/infarct CK-MB: most significant, normalizes in 3-5 days, heart muscle specific SYSTEM FOR ECG INTERPRETATION (“RIRI”):
RATE: count the # of beats on the bottom rhythm strip from far left to mid way through the
column containing V3, multiply by 10
INTERVALS:
~PR: AV block, sinus rhythm, or alternate beat pathway ~QRS: widened? may mean drugs, pacemaker, PVC, LBBB (negative deflection on V1) or RBBB (rSR/positive deflection on V1) ~Sinus (brady/tachy), AV blocks, BBB (LBBB hides acute changes more than RBBB; treat as acute MI if pt has symptoms) ~Atrial Flutter/Fibrillation, PVCs, Paced beats ~ If Unstable Use Electricity: slow = pace, fast = shock ISCHEMIA: check for ST changes and which leads they appear
~ ST should be at baseline in EVERY lead ~ T waves should be upright in all leads except aVR ACUTE CORONARY SYNDROME:
Stable Angina: stable unless exerting themselves
*Chest pain, no ST changes, no changes in Trop/CK Unstable Angina: symptoms at rest, come and go, increasing frequency
*Chest pain, ST depression, no changes in Trop/CK NSTEMI: symptoms at rest, may come and go with increasing frequency or persist/remain until
treated
*Chest pain. ST depression, Trop and CK elevated * Platelet rich, partially-occlusive clot, infarct occurs STEMI: symptoms at rest, usually remain once they appear until treated
*Chest pain, ST elevation, Trop and CK elevated *Platelet rich, occlusive clot, infarct occurs TREATMENT: “NOAH” or “MONA”
Heparin/Anticoagulants
Morphine
Nitro * do not give if on Viagra/Cialis, or suspect a Right Heart Infarct (ie: inferior
lead changes = 15 lead, should receive fluid)

Source: http://www.bcsrt.ca/wp-content/12-and-15-lead-ecg-interpretation.pdf