ECG - visuals Flashcards
Name this rhythm?
sinus bradycardia
HR < 60 bpm (here, about 30 bpm)
pacemaker: SA node
P waves, QRS complexes and PR intervals appear normal
Name this rhythm?
sinus bradycardia
HR < 60 bpm (here, about 40 bpm)
pacemaker: SA node
P waves, QRS complexes and PR intervals appear normal
Name this rhythm?
sinus tachycardia
HR > 100 bpm (but under 180-200, as SA can only go to about 200 as a pacemaker)
HR > 100 bpm healthy in kids and exercising adults
otherwise normal
BONUS: Name some causes of sinus tachycardia?
- naturally high in children
- normally high in adults during exercise
- normally high in adults during emotional event
- could be due to volume depletion (ex. dehydration, blood loss, etc)
- could be due to increased energy demands (hyperthyroid, pheochromocytoma, hyperthermia)
- impaired cardiac filling (pericardial tamponade, tension pneumothorax)
- decreased afterload (septic shock, anaphylaxis)
Name this rhythm?
sinus tachycardia
HR >100 bpm
pacemaker: SA node
Name this rhythm?
First Degree Heart Block
hallmark: wide PR interval, but all P waves conducted
(slow conduction in the AV node, delay in AV node, SA function normal)
possible causes: ischemia, firbrosis
Name this rhythm?
First Degree Heart Block (here with sinus bradycardia)
hallmark: wide PR interval, but all P waves conducted
(slow conduction in the AV node, delay in AV node, SA function normal)
possible causes: ischemia, firbrosis
Name this rhythm?
Second Degree Heart Block Type I (Wenckebach)
Hallmarks: irregular rhythm with pattern
P appearing at regular interval, with some “missing” QRS complexes ( P> QRS)
PR intervals increase, then reset; repeat
Some but not all P waves are conducted to ventricles
As PR intervals increase, they become so long they can no longer “reach” ventricle -> depolarization stops at AV node , thus QRS does not happen. After a “dropped” beat, the AV node “restarts” and QRS complexes re-appear until PR is too long again.
Name this rhythm?
Second Degree Heart Block Type I (Wenckebach)
Hallmarks: irregular rhythm with pattern
P appearing at regular interval, with some “missing” QRS complexes ( P> QRS)
PR intervals increase, then reset; repeat
Some but not all P waves are conducted to ventricles
As PR intervals increase, they become so long they can no longer “reach” ventricle -> depolarization stops at AV node , thus QRS does not happen. After a “dropped” beat, the AV node “restarts” and QRS complexes re-appear until PR is too long again.
Name this rthythm?
Second Degree Heart Block Type II
Hallmarks: More Ps than QRS complexes (regular Ps with some “dropped” QRS complexes). Consistent with type I block, some but not all P waves make it to ventricles
Unline second degree heart block type I, type II has constant PR intervals.
2nd degree block Type II is more dangerous, as it is more likely to progress to 3rd degree block.
Name this rhythm?
Third Degree Heart Block
Hallmarks: P waves and QRS complexes completely dissociated from each other: atrial rate is different from ventricular rate
Complete P wave block, no P waves make it to ventricules
Wide QRS complexes (usually)
Pacemaker for atria: SA node
Pacemaker for ventricles: usually ventricular ectopic (non AV) -> slow travel time for electrical impulses (travelling through myocardium and not through “normal” electrical conducting system -> wide QRS
Pacemaker for ventricles can be low AV (rarely), in which case QRS complexes will be normal
Name this rhythm?
Third Degree Heart Block (complete)
Hallmarks: P waves and QRS complexes completely dissociated from each other: atrial rate is different from ventricular rate
Complete P wave block, no P waves make it to ventricles
Wide QRS complexes (usually)
Pacemaker for atria: SA node
Pacemaker for ventricles: usually ventricular ectopic (non AV) -> slow travel time for electrical impulses (travelling through myocardium and not through “normal” electrical conducting system -> wide QRS
Pacemaker for ventricles can be low AV (rarely), in which case QRS complexes will be normal
Name this rhythm?
Atrial Flutter
“sawtooth” pattern of P waves, many more P waves than QRS complexes
= extreme atrial tachycardia, atrial rates of 300 (much higher than AV node can pick up and conduct) -> AV node blocks every X number of atrial impulses. If AV blocks 1 out of every 2 atrial impulses, 2:1 block (common), there is also 3:1, 4:1 etc
Since atrial contraction can reach 300, sometimes P waves may not be obvious at all. Suspect atrial flutter anytime ventricular rates are above 150.
Name this rhythm?
Atrial Flutter
“sawtooth” pattern of P waves, many more P waves than QRS complexes
= extreme atrial tachycardia, atrial rates of 300 (much higher than AV node can pick up and conduct) -> AV node blocks every X number of atrial impulses. If AV blocks 1 out of every 2 atrial impulses, 2:1 block (common), there is also 3:1, 4:1 etc
Since atrial contraction can reach 300, sometimes P waves may not be obvious at all. Suspect atrial flutter anytime ventricular rates are above 150.
Here atrial flutter with 2:1 block, P waves difficult to see because of high rate.
Name this rhythm?
Atrial Fibrillation (a.fib or AF)
Hallmarks: HR> 80 (but not required), no P waves, very “noisy” patterns
Atrial has multiple “pacemakers” with multidirectional electrical activity quivering, loss of P waves. This uncoordinated electrical activity keeps stimulating AV node until it is out of refractory period and responds with signal propagation - > pattern is irregular and often tachycardic (since so many electrical impulses present in atria)
Be very careful about blood clots! Atria are fibrillating, NOT contracting - > blood is not moving well and can easily form clots -> danger of emboli in other parts of the body (brain, kidneys, …) -> put patient on anti-coagulants & control heart rate
Name this rhythm?
Atrial Fibrillation (a.fib or AF)
Hallmarks: HR> 80 (but not required), no P waves, very “noisy” patterns
Atrial has multiple “pacemakers” with multidirectional electrical activity quivering, loss of P waves. This uncoordinated electrical activity keeps stimulating AV node until it is out of refractory period and responds with signal propagation - > pattern is irregular and often tachycardic (since so many electrical impulses present in atria)
Be very careful about blood clots! Atria are fibrillating, NOT contracting - > blood is not moving well and can easily form clots -> danger of emboli in other parts of the body (brain, kidneys, …) -> put patient on anti-coagulants & control heart rate
Name this rhythm?
Ventricular Fibrillation (V.fib or VF)
Hallmark: No heartrate, no P waves or QRS complexes - uncoordinated waves only
reminder: fibrillation is NOT contraction
there is no ventricular contraction -> no cardiac output -> no blood pressure + no pulse -> no tissue perfusion -> call the code (and use DEfibrillator)
A.fib still leads to perfusion and QRS waves, V. fib - no perfusion at all
Name this rhythm?
Ventricular Fibrillation (V.fib or VF)
Hallmark: No heartrate, no P waves or QRS complexes - uncoordinated waves only
reminder: fibrillation is NOT contraction
there is no ventricular contraction -> no cardiac output -> no blood pressure + no pulse -> no tissue perfusion -> call the code (and use DEfibrillator)
A.fib still leads to perfusion and QRS waves, V. fib - no perfusion at all
Name this rhythm?
Sick Sinus Syndrome (SSS)
= SA dynsfunction, can include sinus bradycardia, tachycardia, block (no impulses exit SA) and arrest (no impulse at all). No P waves exist in the case of sinus block or sinus arrest, as no “travelling” electrical activity generated.
Common SSS causes: hypoxia, myocardial ischemia or infarction, hyperkalemia and digoxin toxicity.
If sinus brady, block or arrest, “escape” beats common due to delay in heart contractions. “Escape” beats are generated by a pacemaker that is not SA node (atrial or ventricular in origin)
Name this rhythm?
Junctional (Escape) Rhythm
SA node or its conduction impaired -> escape rhythms from other pacemakers
In junctional rhythm, the pacemaker is the AV node or proximal bundle of His. Notice rhythm of 40-60 bpm (if more, “accellerated junctional rhythm) and inverted or missing P waves.
Impulse path: AV - > down to ventricles (normal direction) + up to atria (retrograde), causing inverted P waves
Since impulses travel to both ventricles and atria at the same time, there are 3 options:
1) the atria beat first -> inverted P waves, short PR interval, since ventricles contract immediately following atria
2) the atria and ventricles beat
simultaneously -> P waves fuse with QRS complex and are not visible
or 3) the ventricles beat first -> P waves show in ST segment (small, inverted)
Here note “missing” P waves, “buried” in QRS
Name this rhythm?
Junctional (Escape) Rhythm
SA node or its conduction impaired -> escape rhythms from other pacemakers
In junctional rhythm, the pacemaker is the AV node or proximal bundle of His. Notice rhythm of 40-60 bpm (if more, “accellerated junctional rhythm) and inverted or missing P waves.
Impulse path: AV - > down to ventricles (normal direction) + up to atria (retrograde), causing inverted P waves
Since impulses travel to both ventricles and atria at the same time, there are 3 options:
1) the atria beat first -> inverted P waves, short PR interval, since ventricles contract immediately following atria
2) the atria and ventricles beat
simultaneously -> P waves fuse with QRS complex and are not visible
or 3) the ventricles beat first -> P waves show in ST segment (small, inverted)
In this ECG P waves are buried in ST
Name this rhythm?
Junctional (Escape) Rhythm
SA node or its conduction impaired -> escape rhythms from other pacemakers
In junctional rhythm, the pacemaker is the AV node or proximal bundle of His. Notice rhythm of 40-60 bpm (if more, “accellerated junctional rhythm) and inverted or missing P waves.
Impulse path: AV - > down to ventricles (normal direction) + up to atria (retrograde), causing inverted P waves
Since impulses travel to both ventricles and atria at the same time, there are 3 options:
1) the atria beat first -> inverted P waves, short PR interval, since ventricles contract immediately following atria
2) the atria and ventricles beat
simultaneously -> P waves fuse with QRS complex and are not visible
or 3) the ventricles beat first -> P waves show in ST segment (small, inverted)
In this ECG P waves are present, but inverted. Notice short PR intervals
Name this rhythm?
Ventricular Escape Rhythm = Idioventricular Rhythm
An idioventricular rhythm- rhythm generated by a
ventricular ectopic pacemaker (20-40 bpm) when traditional pacemakers (ex. SA and AV) fail. Characterized by wide QRS complex, since electrical impulses are generated in ventricular myocardium.
An idioventricular rhythm can be thought of as “ventricular
bradycardia.
Name this rhythm?
Premature beats
common even in healthy individuals, can be of atrial, ventricular or junctional (AV) origin
Bigeminy - rhythm in which each normal sinus beat is folowed by a premature beat (via ectopic pacemaker)
Trigeminy - 2 healthy beats : 1 premature beat
Atrial premature beats - generated by atrial pacemaker other than SA. Expect early P wave with unusual shape (since electric current not travelling from SA). QRS may be normal or non-existent (if impulse reaches AV during its refractory period)
Ventricular premature beats - generated by ectopic ventricular pacemaker. Expect widened QRS, as impulse is travelling through myocytes (vs fast Purkinje fibers). No related P waves present.
Example 1: ventricular bigeminy. Early beat is from the ventricle. Premature beat is wide with no P wave (don’t confuse the T wave of the sinus beat).
Name this rhythm?
Premature beats
common even in healthy individuals, can be of atrial, ventricular or junctional (AV) origin
Bigeminy - rhythm in which each normal sinus beat is folowed by a premature beat (via ectopic pacemaker)
Trigeminy - 2 healthy beats : 1 premature beat
Atrial premature beats - generated by atrial pacemaker other than SA. Expect early P wave with unusual shape (since electric current not travelling from SA). QRS may be normal or non-existent (if impulse reaches AV during its refractory period)
Ventricular premature beats - generated by ectopic ventricular pacemaker. Expect widened QRS, as impulse is travelling through myocytes (vs fast Purkinje fibers). No related P waves present.
Example 2: atrial trigeminy. The P waves of the premature beat are very slightly different. Early beats are from the atrium. 3rd and 6th beats are the atrial beats. All other beats are sinus beats.
What is AV Nodal Reentrant Tachycardia?
AV Nodal Reentrant Tachycardia (AVNRT) is a common form of Paroxysmal (sudden onset) Supraventricular Tachycardia.
AV node may have several pathways to conduct impulse. In some people, these pathways conduct at different velocities. A fast pathway conducts quickly, but has long refractory period. A slow pathway takes longer, but has a short refractory period.
Normally a stimulus will arrive at AV and take fast pathway through the ventricle. By the time the impulse from slow pathway reaches the bundle of His, it is already in refraction from the fast pathway, stopping slow impulse from conducting futher.
However, if a premature beat occurs, it will likely find fast pathway still in refractory period from previous healthy beat. It will thus take slow pathway, propagating throughout the ventricle, AND in retrograde direction via fast pathway. As it the impulse reaches the top of fast pathway, slow pathway is again ready to conduct, picking up and looping this electric signal over and over again. This creates a reentrant loop, seen on ECG as tachycardia, normal QRS complexes and hidden or inverted P waves that appear after QRS (since signal travels in retrograde manner to the atria).
Name this rhythm?
Torsade de Pointes
Torsade de pointe means “twisting of points”. It is a deadly form of ventricular tachycardia, seen on ECG as QRS complexes of different height and direction, similar in shape to a twisted ribbon. Patients with prolonged QT interval are especially at risk for this condition.
QRS variation happens because electrictrical conduction of each impulse is slightly different from the one before.
Although there is electrical activity, it does not generate needed mechanical contraction of the ventricles - > loss of cardiac output, pulse and blood pressure -> ventricular fibrilation ->death
