ECG Stampede:
Glossary
![book_course_icon@2x](https://www.ecgstampede.com/wp-content/uploads/2022/11/book_course_icon@2x.png)
![Accelerated Idioventricular Rhythm](https://www.ecgstampede.com/wp-content/uploads/2022/11/aivr@2x.png)
AIVR is a rhythm that occurs under conditions of enhanced automaticity. An enhanced ectopic ventricular pacemaker outpaces more superior pacemakers (e.g. sinus node) and, thus, becomes the dominant pacemaker by...
![Acute Pericarditis](https://www.ecgstampede.com/wp-content/uploads/2022/11/pericarditis@2x.png)
The diagnosis is made by meeting 2 of 4 criteria: Typical symptoms (pleuritic, sharp chest pain relieved when leaning forward) New pericardial effusion Presence of friction rub Typical ECG findings...
![Ashman Phenomenon](https://www.ecgstampede.com/wp-content/uploads/2022/11/ashman@2x.png)
This is a phenomenon first described in 1947 in which the refractory period of the conduction system is proportional to the length of the preceding cycle, resulting in aberrant conduction...
![Atrial Fibrillation](https://www.ecgstampede.com/wp-content/uploads/2022/11/afib@2x.png)
Atrial fibrillation occurs when the atria fibrillate and send rapid impulses to the atrioventricular node. The atrioventricular node serves as the "gatekeeper," deciding which signals get through to the infranodal...
![Atrial Fibrillation with WPW](https://www.ecgstampede.com/wp-content/uploads/2022/11/afib-wpw@2x.png)
Normally, the atrioventricular node serves as the “gatekeeper” for signals arising from the atria – it has a refractory period that does not allow ventricular rates much faster than about...
![Atrial Flutter](https://www.ecgstampede.com/wp-content/uploads/2022/11/aflutter@2x-1.png)
Atrial flutter occurs from a reentrant circuit around the tripcuspid valve in the right atrium. It is an organized rhythm that is generally characterized by an atrial rate around 300...
![Atrial Tachycardia](https://www.ecgstampede.com/wp-content/uploads/2022/11/atrial-tachycardia@2x.png)
Atrial tachycardia, or focal atrial tachycardia, is result of a micro-reentrant circuit or an automatic focus. The atrial rate is greater than 100 bpm and less that 250 bpm. Atrial...
![Atrioventricular Nodal Reentrant Tachycardia](https://www.ecgstampede.com/wp-content/uploads/2022/11/avnrt@2x.png)
Atrioventricular nodal reentrant tachycardia (AVNRT) is caused by a reentrant loop within the atrioventricular node. With AVNRT, the atrioventricular node has two pathways, fast and slow, which allows for a...
![Atrioventricular Reentrant Tachycardia](https://www.ecgstampede.com/wp-content/uploads/2022/11/svt@2x.png)
Atrioventricular reentrant tachycardia, or atrioventricular reciprocating tachycardia, is a type of supraventricular tachycardia in which an accessory pathway provides an abnormal connection between the atria and ventricles. Patients with an...
![Bifascicular Block](https://www.ecgstampede.com/wp-content/uploads/2022/11/bifascicular@2x.png)
When two of three fascicles are blocked, it is termed bifascicular block. While a left bundle branch block (LBBB) technically involves disruption of two fascicles, this term is typically reserved...
![Brugada Syndrome](https://www.ecgstampede.com/wp-content/uploads/2022/11/brugada@2x.png)
Brugada syndrome is a sodium channelopathy with a characteristic ECG pattern (pseudo-right bundle branch block pattern with down sloping ST segment elevation in V1 and/or V2) and an increased risk...
![Cerebral T waves](https://www.ecgstampede.com/wp-content/uploads/2022/11/cerebral@2x.png)
Cerebral T waves are large T wave inversions and are likely the result of a sympathetic surge causing repolarization abnormalities. Cerebral T waves are rare and generally resolve over time.
![Dextrocardia](https://www.ecgstampede.com/wp-content/uploads/2022/11/dextrocardia@2x.png)
A rare congenital condition where the heart is on the right side of the thorax. Electrocardiographically, this results in right axis deviation and positive QRS complex in aVR with upright...
![Digoxin Toxicity](https://www.ecgstampede.com/wp-content/uploads/2023/01/digoxin@2x.png)
Digoxin, or digitalis, is associated with several electrocardiographic changes and, in toxicity, can precipitate a myriad of tachydysrhythmias and bradydysrhythmias. Increased intracellular calcium increases automaticity, and atrioventricular blockade increase vagal...
![Early Repolarization](https://www.ecgstampede.com/wp-content/uploads/2022/11/ber@2x.png)
Electrocardiographic features of early repolarization include diffuse ST elevations that are most pronounced in the precordial leads (typically V2-5) and in proportion to the amplitude of the QRS complex. The...
![First Degree Atrioventricular Block](https://www.ecgstampede.com/wp-content/uploads/2022/11/av1@2x.png)
First degree blocks are characterized by a prolonged PR interval (greater than 200 ms) and are usually seen it active, healthy patients without heart disease. It usually represents high vagal...
![Global Subendocardial Ischemia](https://www.ecgstampede.com/wp-content/uploads/2022/11/global-ischemia@2x.png)
Multilead ST-segment depression with ST-segment elevation in aVR is a pattern that has been recognized as a strong predictor of left main coronary artery or 3-vessel disease; however, occlusive coronary...
![Hyperacute T Waves](https://www.ecgstampede.com/wp-content/uploads/2022/11/hyperacute@2x.png)
Hyperacute T waves are seen early in occlusive myocardial infarction and are characterized by a broad base and rounded top; they are large in amplitude when compared to the QRS...
![Hypercalcemia](https://www.ecgstampede.com/wp-content/uploads/2022/11/hypercalcemia@2x.png)
The identification of ECG changes associated with electrolyte derangements including hypercalcemia is critical as the associated conduction abnormalities carry the risk of progression to fatal ventricular dysrhythmias (such as ventricular...
![Hyperkalemia](https://www.ecgstampede.com/wp-content/uploads/2022/11/hyperkalemia@2x.png)
Electrocardiographic findings of hyperkalemia tend to follow a progression as toxicity progresses. Often, the earliest finding is narrow-based, peaked T waves, and at the extreme end of the hyperkalemia spectrum,...
![Hypertrophic Cardiomyopathy](https://www.ecgstampede.com/wp-content/uploads/2022/11/hcm@2x.png)
Hypertrophic cardiomyopathy is the most common cause of sudden cardiac death among individuals under 40 years of age, and a cause of outflow obstruction. A systolic murmur along the left...
![Hypocalcemia](https://www.ecgstampede.com/wp-content/uploads/2022/11/prolonged-qt@2x.png)
Hypokalemia, hypomagnesemia, and hypocalcemia can all cause a prolongation of the QT interval. While hypokalemia and hypomagnesemia both delay the repolarization phase (phase 3) of the of the cardiac action...
![Hypokalemia](https://www.ecgstampede.com/wp-content/uploads/2022/11/hypokalemia@2x.png)
Hypokalemia, hypomagnesemia, and hypocalcemia can all cause a prolongation of the QT interval. While hypokalemia and hypomagnesemia both delay the repolarization phase (phase 3) of the of the cardiac action...
![Hypothermia](https://www.ecgstampede.com/wp-content/uploads/2022/11/hypothermia@2x.png)
Hypothermia can cause J waves, or Osborn waves, bradycardia, a prolonged QT, and motion artifact from shivering.
![Left Anterior Fascicular Block](https://www.ecgstampede.com/wp-content/uploads/2022/11/lafb@2x.png)
The normal infranodal conduction system divides into the right and left bundles, the latter is further subdivided into anterior and posterior divisions or “fascicles.” Disruption of both fascicles produces the...
![Left Atrial Enlargement](https://www.ecgstampede.com/wp-content/uploads/2022/11/laa@2x.png)
Atrial enlargement can be determined by analyzing the P waves in leads II and V1. The first half of the P wave represents right atrial depolarization, while the second half...
![Left Bundle Branch Block](https://www.ecgstampede.com/wp-content/uploads/2022/11/lbbb@2x.png)
Left bundle branch block (LBBB) occurs when the left bundle no longer conducts, and the signal must pass to the left ventricle via myocyte-to-myocyte conduction. This pattern of conduction is...
![Left Posterior Fascicular Block](https://www.ecgstampede.com/wp-content/uploads/2022/11/lpfb@2x.png)
The normal infranodal conduction system divides into the right and left bundles, the latter is further subdivided into anterior and posterior divisions or “fascicles.” Disruption of both fascicles produces the...
![Left Ventricular Aneurysm](https://www.ecgstampede.com/wp-content/uploads/2022/11/lva@2x.png)
In the age of reperfusion, left ventricular aneurysms have become quite rare, but in the absence of reperfusion, it is a common structural complication of acute myocardial infarction, occurring in...
![Left Ventricular Hypertrophy](https://www.ecgstampede.com/wp-content/uploads/2022/11/lvh@2x.png)
There are several criteria out there for left ventricular hypertrophy, and none of them are particularly sensitive. They’re all less than 50% sensitive, but they’re usually quite specific - 85...
![Lewis Lead](https://www.ecgstampede.com/wp-content/uploads/2022/11/lewis@2x.png)
The Lewis lead describe a different positioning of the limb leads in order to better visualize atrial activity. The Lewis lead can help better visualize atrial activity. Lead placement...
![Limb Lead Reversal](https://www.ecgstampede.com/wp-content/uploads/2022/11/dextrocardia@2x-1.png)
Between 0.4 and 4% of ECG’s obtained in various settings demonstrate features of lead misplacement. Lead misplacement may either obscure important findings or simulate the appearance of ectopic rhythms, conduction...
![Low Voltage](https://www.ecgstampede.com/wp-content/uploads/2022/11/low-voltage@2x.png)
The traditional definition of low voltage is QRS amplitudes less than 5 mm in all limb leads or less than 10 mm in all precordial leads. The differential for low...
![Multifocal Atrial Tachycardia](https://www.ecgstampede.com/wp-content/uploads/2022/11/mfat@2x-1.png)
Multifocal atrial tachycardia (MAT) is an irregularly irregular rhythm, typically between 100-150 beats per minute, that arises from multiple ectopic foci within the atria. It is a rare condition that...
![Paced Rhythms](https://www.ecgstampede.com/wp-content/uploads/2022/11/paced@2x.png)
Pacemakers are programmed with five variables, the first three are relevant to emergency physicians. Pacemaker codes....
![Pacemaker Malfunction](https://www.ecgstampede.com/wp-content/uploads/2022/11/pace-failure@2x.png)
Failure to pace occurs when the paced stimulus is not generated when expected. Pacemaker spikes are decreased or absent. It is usually caused by oversensing but can also be caused...
![Pacemaker Mediated Tachycardia](https://www.ecgstampede.com/wp-content/uploads/2022/11/pmt@2x.png)
Pacemaker-mediated tachycardia (PMT), or endless loop tachycardia, is a reentrant tachycardia in which the pacemaker forms the anterograde pathway and the atrioventricular node forms the retrograde pathway, leading to a...
![Persistent Juvenile T Wave Pattern](https://www.ecgstampede.com/wp-content/uploads/2024/01/juvenile-t@2x.png)
The T waves in the right precordial leads (V1 through V3) are asymmetrically inverted in childhood and become upright (except for V1 and occasionally V2) by adulthood. In predominantly black...
![Polymorphic Ventricular Tachycardia](https://www.ecgstampede.com/wp-content/uploads/2022/11/pvt@2x.png)
Polymorphic ventricular tachycardia (PVT) is a form of ventricular tachycardia in which there are multiple ventricular foci with the resultant QRS complex varying in amplitude, axis, and duration. The most...
![Poor R-wave Progression](https://www.ecgstampede.com/wp-content/uploads/2023/02/prwp@2x.png)
Poor R wave progression is a non-specific finding that is suggestive of prior anterior myocardial infarction. It is a poorly defined term that implies diminished amplitude of the R wave...
![Posterior Myocardial Infarction](https://www.ecgstampede.com/wp-content/uploads/2022/11/posterior-stemi@2x.png)
Posterior myocardial infarction is commonly confused with anterior subendocardial ischemia; however, the T waves are expected to be negatively deflected with anterior subendocardial ischemia (unless early on when they can...
![Prolonged QT](https://www.ecgstampede.com/wp-content/uploads/2022/11/prolonged-qt@2x-1.png)
Measuring the QT can be challenging, and many different methods exist. One simple method is the “half the RR” rule – the QT interval is prolonged if it occupies more...
![Pulmonary Embolism](https://www.ecgstampede.com/wp-content/uploads/2022/11/pe@2x.png)
Tachycardia, S1Q3T3, tall P wave in II, ST elevation in right-sided leads (aVR, V1, III), right axis deviation, new right bundle branch block, new incomplete right bundle branch block, and...
![Right Atrial Enlargement](https://www.ecgstampede.com/wp-content/uploads/2022/11/rae@2x.png)
Atrial enlargement can be determined by analyzing the P waves in leads II and V1. The first half of the P wave represents right atrial depolarization, while the second half...
![Right Bundle Branch Block](https://www.ecgstampede.com/wp-content/uploads/2022/11/rbbb@2x.png)
Right bundle branch block (RBBB) occurs when the right bundle no longer conducts, and the signal must pass to the right ventricle via myocyte-to-myocyte conduction. This pattern of conduction is...
![Right Heart Strain](https://www.ecgstampede.com/wp-content/uploads/2022/11/rhs@2x.png)
Tachycardia, S1Q3T3, tall P wave in II, ST elevation in right-sided leads (aVR, V1, III), right axis deviation, new right bundle branch block, new incomplete right bundle branch block, and...
![Second Degree Atrioventricular Block 2:1](https://www.ecgstampede.com/wp-content/uploads/2022/11/av2-2-1@2x.png)
With 2:1 atrioventricular block, it is impossible to know whether it is Mobitz I (nodal) or Mobitz II (infranodal) based on the surface ECG; therefore, 2:1 AV block is simply...
![Second Degree Atrioventricular Block – Mobitz I](https://www.ecgstampede.com/wp-content/uploads/2022/11/av2-1@2x.png)
Mobitz I occurs when conduction is progressively delayed through the AV node and eventually fails. It is represented by progressively prolonging PR intervals followed by a “dropped” P wave. It...
![Second Degree Atrioventricular Block – Mobitz II](https://www.ecgstampede.com/wp-content/uploads/2022/11/av2-2@2x.png)
Mobitz II occurs when the infranodal conduction system intermittently fails, resulting in intermittently “dropped” P waves but consistent PR intervals when conducted. Mobitz II usually occurs with preexisting conduction disease...
![Sgarbossa Criteria](https://www.ecgstampede.com/wp-content/uploads/2022/11/sgarbossa@2x.png)
With left bundle branch block, expected ST/T changes include discordant ST depression and T wave inversion in the lateral leads (I, aVL, V5, V6). Discordance describe ST deviation in the...
![Sinus Node Dysfunction](https://www.ecgstampede.com/wp-content/uploads/2022/11/sa-dysfunction@2x.png)
Sinus node dysfunction is historically referred to as sick sinus syndrome. It is due to age-related fibrotic degeneration of the sinus node resulting in impaired signal generation and propagation which...
![Sodium Channel Toxicity](https://www.ecgstampede.com/wp-content/uploads/2022/11/na@2x.png)
Classily, sodium channel toxicity was described in tricyclic overdoses,96 but many drugs can cause toxic sodium channel effects including antiarrhythmics (e.g., lidocaine, phenytoin, propafenone, flecainide, amiodarone, sotalol), antiepileptic medications (e.g.,...
![ST-elevation Myocardial Infarction](https://www.ecgstampede.com/wp-content/uploads/2022/11/stemi@2x.png)
ST-elevation myocardial infarction (STEMI) is a term used to describe a transmural myocardial infarction that benefits from immediate percutaneous intervention. According to the fourth universal definition, STEMI is defined as...
![Supraventricular Tachycardia](https://www.ecgstampede.com/wp-content/uploads/2022/11/svt@2x-1.png)
In the setting of regular, narrow complex tachycardia, P waves can aid the diagnosis but are often absent. At faster rates, sinus tachycardia can be obscured when P waves are...
![Supraventricular Tachycardia with Aberrancy](https://www.ecgstampede.com/wp-content/uploads/2022/11/svt-a@2x.png)
The differential for wide complex tachycardia includes ventricular tachycardia (VT), supraventricular tachycardia (SVT, e.g., atrial flutter, atrial tachycardia, or atrioventricular nodal reentrant tachycardia) with aberrancy (i.e., bundle branch block), antidromic...
![T-wave Inversions](https://www.ecgstampede.com/wp-content/uploads/2022/11/twi@2x.png)
The differential diagnosis for T-wave inversions is broad and includes, but is not limited to: ischemia, hypertrophy, bundle branch blocks, early repolarization variants, persistent juvenille T wave pattern, cardiac memory,...
![Third Degree Atrioventricular Block](https://www.ecgstampede.com/wp-content/uploads/2022/11/av3@2x.png)
Third degree, or complete, heart block is characterized by atrioventricular dissociation - atrial impulses fail to conduct to the ventricles and, therefore, the atria and ventricles act independently of each...
![Torsade de Pointes](https://www.ecgstampede.com/wp-content/uploads/2022/11/torsades@2x.png)
Torsades de pointes (TdP) is a specific form of polymorphic ventricular tachycardia occurring in the context of QT prolongation — it has a characteristic morphology in which the QRS complexes...
![Trifascicular Block](https://www.ecgstampede.com/wp-content/uploads/2022/11/trifascicular@2x.png)
The term “trifascicular block” is a misnomer as a true block of all three fascicles (the right bundle branch, left anterior fascicle and left posterior fascicle) would result in complete...
![Ventricular Fibrillation](https://www.ecgstampede.com/wp-content/uploads/2022/11/vfib@2x.png)
Ventricular fibrillation is a chaotic, disorganized rhythm in which the ventricles rapidly and asynchronously quiver. It is fatal and warrants immediate electrical cardioversion; otherwise, asystole is imminent. Mechanisms of ventricular...
![Ventricular Pre-excitation](https://www.ecgstampede.com/wp-content/uploads/2022/11/preexcitation@2x.png)
Pre-excitation is a condition in which an accessory pathway exists between the atria and the ventricles, often referred to as the bundle of Kent. When the accessory pathway conducts in...
![Ventricular Tachycardia](https://www.ecgstampede.com/wp-content/uploads/2022/11/vtach@2x.png)
Ventricular tachycardia (VT) can be difficult to differentiate from supraventricular tachycardia with aberrancy. When in doubt, it is safest to treat most wide complex tachycardia as VT. Up to 80%...
![Wellens Syndrome](https://www.ecgstampede.com/wp-content/uploads/2022/11/wellens@2x.png)
Wellens syndrome comes in two electrocardiographic varieties – biphasic T waves (up then down, type A) or deeply inverted and symmetric T waves in the anterior precordial leads V1-V3 (type...