EKG 101 (Help, I’m a Doctor!) Scott Ewing, D.O. July 5, 2006

The EKG Paper Time intervals indicated for the thick and thin vertical grid lines on the ECG paper are appropriate for the standard paper speed of 25 mm/sec Amplitudes indicated for the thick and thin horizontal grid lines are appropriate for the standard gain of 10 mm/mV Each small square is therefore 0.04 s × 0.1 mV, and each large square is 0.20 s × 0.5 mV

Normal EKG Normal individual's 12-standard ECG leads are presented in the classical format of four columns consisting of three leads each Arrows indicate the small Q waves that may normally occur in leads I, II, aVL, V4, V5, and V6 Asterisk in lead V3 indicates the minute Q wave that may rarely occur normally

Rate

Rhythm

Axis Normal axis (NA) Right-axis deviation (RAD) Left-axis deviation (LAD) Extreme axis deviation (EAD) +60 degrees +150 degrees –30 degrees –60 degrees –120 degrees

P Wave

PR Interval

QRS Complex

ST Segment

Normal R Wave Progression Typical panoramic display of the six precordial leads of the ECG, illustrating the normal progression and regression of R- and S-wave amplitudes

Normal QRS Complex 25-year-old normal woman 48-year-old man with acute chest pain of noncardiac origin 54-year-old woman with acute chest pain of noncardiac origin 20-year-old normal man 63-year-old man with aortic valve disease

Acute Ischemia – ST Depression

Acute Ischemia – ST Depression

Acute Ischemia – ST Depression

Acute Ischemia - T Wave Changes

Infarct - ST Elevation

Inferior Infarct – ST Elevation

Inferior Infarct – ST Elevation

Posterior Infarct – ST Elevation!!!

Old Infarct - Anterior Q Waves

Old Infarct - Inferior Q Waves

Persistent ST Changes

Persistent T Wave Changes

34 Year Old Male With Chest Pain

60-year-old Male

Anterior Ischemia ECG shows sinus rhythm with ventricular ectopy, left axis deviation, consistent with left anterior fascicular block (hemiblock), and T wave inversions in V2-V5 with subtle upward bowing of the ST segments ST-T abnormalities in I and aVL Symmetric T wave inversions, especially with upward bowing of the ST segments is highly suggestive of ischemia in the left anterior descending distribution (LAD) in this context Most expeditious test to order is a cardiac catheterization, which showed significant LAD (and obtuse marginal) disease

Elderly Male

Severe Ischemia ECG shows sinus rhythm at about 65 bpm with profound ischemic ST segment depression, most marked in the precordial leads, consistent with severe subendocardial ischemia and probable non-Q wave myocardial infarction QT interval is not prolonged (0.41 second at rate of 65 bpm) and the PR interval is at the upper limits of normal (0.20 second) Broad P waves are present (biphasic in lead V1) consistent with left atrial abnormality Q waves in the infero-lateral leads are consistent with prior myocardial infarction(s) Profound ST depressions of this type usually indicate severe multivessel disease, and sometimes left main coronary disease The patient experienced severe chest pain and was transferred from an outside facility in cardiogenic shock En route to the cardiac catheterization laboratory, he developed refractory pulseless electrical activity and ventricular fibrillation.

84-year-old Female

NQWMI ECG shows left ventricular hypertrophy (LVH) plus left atrial abnormality (LAA) QRS axis is somewhat leftward (-7 degrees) Although LVH alone may be associated with ST-T abnormalities (sometimes referred to as a "strain pattern"), like those in lead aVL, the prominent horizontal or downsloping ST depressions in other leads (I, II, aVF, V5, V6) here are strongly suggestive of ischemia superimposed on LVH The patient had positive cardiac enzymes and underwent cardiac catheterization showing left main and three vessel coronary disease, followed by coronary artery bypass graft surgery.

34-year-old male

Acute Anterior MI Classic findings of acute anterior wall Q wave myocardial infarction Reciprocal inferior ST depressions Hyperacute T waves Distribution of changes is consistent with a proximal LAD occlusion Confirmed at cardiac catheterization and treated with PTCA and stenting Premature atherosclerosis with multiple risk factors including hypertension, hyperlipidemia, family history and tobacco.

68-year-old female

Acute Anterior MI Note Q waves and loss of R waves V1 - V4 ST elevation in V2 - V5/V6 Left anterior fascicular block is also present, but does not account for the loss of R wave progression The patient had had a very recent anterior MI Cardiac catheterization revealed 3-vessel disease with a 90% mid-LAD "culprit" lesion

53-year-old female

Acute Lateral MI ST elevations in I and aVL Probable reciprocal ST depressions inferiorly consistent with acute lateral MI Remember: ST elevations like this are never reciprocal but indicate the primary region of ischemia (diagonal or circumflex lesion) Confirmed left circumflex occlusion at catheterization

36-year-old male

Acute Pericarditis Always consider myocardial infarction first when you see ST elevations But don't forget the differential diagnosis of ST elevations Ischemic heart disease Pericarditis Left bundle branch block (LBBB) Normal ("early repolarization") variant Two features here point to pericarditis First, diffuseness of the ST elevations (I, II, III, aVF, V3-V6) Second, PR depression in II, aVF, V4-V6 and PR elevation seen in aVR (attributed to subepicardial atrial injury)

49-year-old male

Acute Pericarditis Diffuse ST segment elevations (I, II, aVF, V2-V6) Subtle PR segment deviations (elevated in aVR and depressed in the inferolateral leads) ST elevations are due to a ventricular current of injury from the pericardial inflammation PR changes are due to an associated atrial current of injury Note that the PR and ST segment vectors point in opposite directions, i.e., PR up and ST down in aVR and PR down and ST up in inferolateral leads Resting sinus tachycardia is noted. The patient had a fever but no pericardial effusion

Middle aged female

Acute Myocardial Infarction Marked inferior and lateral ST segment elevation ST segment depression in anterior leads V1-V4 ST elevations (“current of injury” pattern) indicate transmural ischemia of the infero-lateral wall ST depression most consistent with reciprocal change from the ST elevation generated by the acute posterior and lateral ischemia Remember, acute pericarditis causes diffuse ST segment elevation (e.g., leads I, II, III, aVL, aVF, and the precordial leads) Reciprocal ST depressions of the type seen here (V1-V4), are never a feature of pericarditis alone Cardiac catheterization revealed acute occlusion of a dominant left circumflex coronary artery (along with occlusion of a smaller RCA)