Premature Ventricular Complex: Wide QRS
ST elevation/ST depression/flipped T waves
ST elevation throughout leads
Right Bundle Branch Block: wide QRS and “rabbit ears” or R-R in V1 or V2
Associated with absent Q waves in leads I, aVL, and V6; a large, wide, and positive R wave in leads I, aVL, and V6; Wide QRS and “rabbit ears” or RSR' in V5 or V6.
and prolongation of the QRS complex to greater than 0.12 seconds.
Delta wave = slurred upswing on QRS
First degree A-V block?
Prolonged P-R interval (0.2 second)
Second degree A-V block?
Dropped QRS; not all P waves transmit to produce ventricular contraction
Second-degree block with progressive delay in P-R interval prior to dropped beat
Third-degree A-V block?
Complete A-V dissociation; random P wave and QRS
Prolongation of QT interval on ECG (QTc >450 msec in males or >470 msec in females).
Ischemic changes in the anterolateral leads (ST-segment depression and T-wave inversion).
Third-degree atrioventricular block, or complete heart block, refers to a lack of atrioventricular conduction (characterized by lack of conduction of all atrial impulses to the ventricles),
Acute myocardial infarction manifesting as a new left bundle branch block on electrocardiogram and complicated by ischemic mitral regurgitation and heart failure. Electrocardiographically, left bundle branch block is associated with absent Q waves in leads I, aVL, and V6; a large, wide, and positive R wave in leads I, aVL, and V6; and prolongation of the QRS complex to greater than 0.12 seconds. Repolarization abnormalities are present and consist of ST-segment and T wave vectors directed opposite to the QRS complex.
Second-degree atrioventricular block is diagnosed by the presence of isolated P waves that are not followed by a QRS complex. There are two possible forms: Mobitz type I (Wenckebach), with progressive prolongation of the PR interval until the dropped beat, and Mobitz type II, with a constant PR interval and periodic dropped beats.
Atrial fibrillation is caused by rapid and uncoordinated electrical activation within the atria. The electrocardiogram shows an absence of P waves and an irregular ventricular response.
Ventricular preexcitation by an accessory atrioventricular connection, with a short P-R interval, prolonged QRS duration, and slurred onset of the QRS (delta wave) interval. With paroxysmal tachyarrhythmias, this pattern is diagnostic for Wolff-Parkinson-White syndrome.
Atrial flutter is characterized by a saw-tooth pattern on electrocardiogram that is most noticeable in the inferior leads.
Multifocal atrial tachycardia is characterized on electrocardiograms by three or more P wave morphologic patterns and variable P-R intervals.
In a patient with a wide-complex tachycardia with a history of coronary artery disease or cardiomyopathy, ventricular tachycardia is the most likely diagnosis.
Previous inferior wall myocardial infarction on electrocardiogram (Q waves in leads II, III, and aVF).
Atrial tachycardia is distinguished from atrial flutter by:
Its somewhat slower atrial rate (150-250 bpm as opposed to 250-350 bpm).
Electrocardiogram showing abnormal Q waves in leads V3-V5 and ST-segment elevation in leads V2-V5.
ECG Leads and Anatomic Correlates
II, III, aVF Inferior - RCA
V1-V3 Anteroseptal - LAD
V4-V6; possible elevations in I and aVL Lateral and apical - LCx
V1-V3 (ST depression) Posterior walla - “Dominant” vessel (RCA or LCx)
V4R Right ventriclea - Right coronary artery
ECG Criteria for STEMI
Two or More Contiguous ECG Leads
II, III, aVF ≥0.1 mVa at J-point for most leads
V1-V3 ≥0.15 mV for V2-V3 for women
V4-V6 ≥0.2 mV for V2-V3 for men ≥ 40 y
I, aVL ≥0.25 mV for V2-V3 for men <40 y
ST-segment depression (indicates true posterior wall MI)
V1-V3 ≥0.1 mV (Often has tall R waves in V1-V3)
New LBBB New finding or presumed new
Rate, Rhythm (P before each QRS)
P-R (120-200ms or 3-5 little boxes)
QRS < 120ms (3 little boxes)
QT (50-500ms or < .5 R-R
P wave for atrial
R wave for ventricular