Define specific rhythms

Question 1

Sinus Tachycardia
define

Answer 1

Sinus Tachycardia is a fast heartbeat related to a rapid firing of the SA node. The electrical signals from your heart’s SA node are telling your heart to beat faster than normal. Sinus Tachycardia most often results from increased sympathetic stimulation (i.e. due to pain, fever, increased oxygen demand, and/or hypovolemia).

Question 2

Sinus Tachycardia
rate/rhythm ect.

Answer 2

Rate: >100bpm but under <150
Rhythm: Atrial (P-P): regular/Vent.
(RR): regular
P-Wave: present, upright
P-R Interval: 0.12 - 0.20sec / (3-5 small squares)
QRS Complex: <0.12sec / (<3 small squares)
ST Segment: Level w isoelectric line
T-wave: rounded, slightly asymmetrical

Question 3

Sinus bradycardia
define

Answer 3

Sinus bradycardia is a regular but unusually slow heartbeat (less than 60 bpm). Sinus bradycardia is often seen as a normal variation in athletes, during sleep, or in response to a vagal maneuver. Not normally a problem unless the rate is < 50 bpm, a slow rhythm reduces cardiac output.

Question 4

Sinus bradycardia
rate/rhythm ect.

Answer 4

Rate: <60bpm – problem <50
Rhythm: Atrial (P-P): regular / Vent. (R-R): regular
P-Wave: present, upright
P-R Interval: 0.12 - 0.20sec / (3-5 small squares)
QRS Complex: <0.12sec / (<3 small squares)
ST Segment: Level w isoelectric line
T-wave: rounded, slightly asymmetrical

Question 5

Sinus arrhythmia
define

Answer 5

Sinus arrhythmia is a normal physiological phenomenon, most commnonly seen in young, healthy people. It is characterised by the P-P (time between heartbeats) interval gradually lengthening and shortening in a cyclical (regularish) fashion. The irregular pattern of this rhythm fluctuates with inspiration (HR increases) and expiration (HR decreases).

Sinus arrhythmia results from intrathoracic pressure changes during breathing:
- Inspiration decreases intrathoracic pressure which increases venous return. Vagus nerve stimulation decreases during inspiration leading to a heart rate increase
- Expiration increases intrathoracic pressure again which decreases venous return. Vagus nerve stimulation increases again during expiration leading to heart rate decrease.

Question 6

Sinus arrhythmia
rate/rhythm ect.

Answer 6

Rate: 60-100 or <60bpm
Rhythm: Atrial (P-P): irregular / Vent. (R-R): irregular (varies 0.08sec)
P-Wave: present, upright
P-R Interval: 0.12 - 0.20sec / (3-5 small squares)
QRS Complex: <0.12sec / (<3 small squares), narrow
ST Segment: Level w isoelectric line
T-wave: rounded, slightly asymmetrical

Question 7

Atrial tachycardia
define

Answer 7

Atrial tachycardia is a form of supraventricular tachycardia (SVT), originating within the atria but outside of the sinus node. If observing the rhythm when it begins, there will likely be a noticeable sudden change in heart rate, in this case, there are ‘P waves’ but these look quite different to normal P waves. They might be flatter or, commonly, more peaked (see rhythm strip below). The pathophysiology of atrial tachycardia involves the abnormal firing of electrical impulses from an area in the atria other than the sinus node.

Question 8

Atrial tachycardia
rate/rhythm ect.

Answer 8

• Rate: >100bpm (commonly >120bpm)
• Rhythm: Atrial (P-P): regular / Vent. (R-R): regular
• P-Wave: abnormal, may be hidden (abnormal including tall and peaked, flattened and biphasic
  (having two phases; at more rapid firing rates P wave can become hidden in QRS)
• P-R Interval: <0.12sec, may vary (<3 small sq.), may not be measurable
• QRS Complex: <0.12sec (<3 small sq.)
• ST Segment: Level w isoelectric line
• T-wave: rounded, slightly asymmetrical (However, the T-wave morphology may be distorted by the fast atrial rate, making it difficult to interpret)

It is important to note that the presence of P waves on the ECG is a key feature that helps distinguish atrial tachycardia from other supraventricular tachycardias, such as atrial fibrillation or atrial flutter, where P waves may not be visible.

Question 9

Alternative pacemakers than the SA node: atrial
define and what happens

Answer 9

The SA node is the normal and preferred pacemaker to initiate each QRS and each cardiac rhythm

Where the alternative pacemaker is within the atria and above the AV node, there will be some sort of different ‘P’ wave evident. Frequently the different beats will be either in isolation, a short salvo (run or group) or a longer burst that reverts back to the normal underlying rhythm. Where this occurs, a comparison between the two different P waves can be made

From the AV node onward, conduction will follow the normal pathway through the ventricles. This means there will be a normal-looking QRS complex following

Question 10

Wandering atrial pacemaker (WAP)
define

Answer 10

Wandering atrial pacemaker (WAP) is a type of cardiac arrhythmia that is characterized by an irregular heartbeat due to the presence of multiple pacemaker sites in the atria, which results in a shifting of the dominant pacemaker site. The SA node, located in the right atrium, is the heart’s natural pacemaker and generates the electrical impulses that regulate the heartbeat. However, in WAP, additional pacemaker sites in the atria may become active, resulting in an irregular heartbeat.

The electrical impulses generated by these multiple pacemaker sites can result in an irregular rhythm. Different appearing P waves, PR intervals and sometimes even no P waves. Clinically these rhythms are rarely a problem

Question 11

Multifocal atrial tachycardia (MAT)
define

Answer 11

Multifocal atrial tachycardia (MAT) is a type of cardiac arrhythmia that is characterized by an irregularly irregular rhythm with at least three different P-wave morphologies (shape) on the electrocardiogram (ECG). The pathophysiology of MAT involves the presence of multiple ectopic foci (abnormal pacemaker sites within the heart (outside of the SA node) that display automaticity) in the atria that are firing at a rate faster than the SA node.

This is a tachycardia version of a wandering atrial pacemaker.

Clinically, this rhythm is rarely a problem in itself but occasionally might require ventricular rate control if it persists. It is however commonly associated with hypoxia and COPD.

Question 12

Wandering atrial pacemaker (WAP)
rate/rhythm ect.

Answer 12

Rate: 60-100bpm
Rhythm: Atrial (P-P): irregular / Vent. (R-R): Regular
P-Wave: differing in shape, may not be visible (due to the shifting of the dominant pacemaker site)
P-R Interval: will vary, differing in shape; may vary with each beat due to the shifting of the dominant pacemaker site
QRS Complex: <0.12sec (<3 small squares)
ST Segment: Level w isoelectric line
T-wave: rounded, slightly asymmetrical

Question 13

Multifocal atrial tachycardia (MAT)
rate/rhythm ect.

Answer 13

Rate: >100bpm
Rhythm: Atrial (P-P): irregular / Vent. (R-R): regular
P-Wave: abnormal, may be hidden (at high rate range P wave can become hidden in QRS)
P-R Interval: <0.12sec, may vary (<3 small sq.), may not be measurable (longer or shorter)
QRS Complex: <0.12sec (<3 small sq.), may be narrow (indicating that the arrhythmia is originating above the ventricles)
ST Segment: Level w isoelectric line (ST depression)
T-wave: rounded, slightly asymmetrical (maybe inversion)

Question 14

Atrial flutter
define

Answer 14

Atrial flutter is a type of cardiac arrhythmia that is characterized by a rapid and regular atrial rhythm with an atrial rate typically between 250-350 beats per minute, and a ventricular rate that may be regular or irregular depending on the degree of atrioventricular block.

The pathophysiology of atrial flutter involves the presence of a re-entrant circuit within the atria that causes the rapid and regular atrial contractions.

The circuit is usually initiated by a premature atrial beat or a focus of automaticity that generates an ectopic impulse that travels along a slower conducting pathway, creating a loop of conduction. The loop of conduction can continue to circulate around the atrium at a very fast rate, producing a regular, sawtooth-shaped pattern of flutter waves on the electrocardiogram.

Determine the number of impulses conducted through the AV node – expressed as a conduction ratio e.g. 2:1 3: 1 4:1etc.
The most common presentation is 2:1 making a heart rate of 150bpm typical finding

Question 15

Atrial flutter
rate/rhythm ect.

Answer 15

Rate: Atrial: 250-400bpm / Vent.: variable (may be slower in patients with atrioventricular block around 150bpm)
Rhythm: Atrial (P-P): regular / Vent. (R-R): regular (The atrial and ventricular rates may be different due to varying degrees of atrioventricular block)
P-Wave: many, regular, sawtooth (sawtooth-shaped pattern of flutter waves on the ECG, with a repeating sequence of negative and positive deflections)
P-R Interval: variable
QRS Complex: <0.12sec (<3 small squares)
ST Segment: Level w isoelectric line
T-wave: rounded, slightly asymmetrical

Question 16

Atrial Fibrillation
define

Answer 16

Atrial fibrillation (AF) is a supraventricular tachycardia (SVT) and is the most common sustained dysrhythmia in the elderly and is characterised by multiple pacemaker focal points in the atria resulting in an “irregularly irregular” ventricular response (no pattern). Atrial fibrillation is a chaotic rhythm with recognizable QRS complexes. The chaotic rhythm pattern and the absence of P waves are the hallmarks of this dysrhythmia.

Atrial Fibrillation can become problematic when very fast with the combination of reduced time for ventricular filling and loss of atrial input

There is a huge association between atrial fibrillation and acute stroke. The fibrillating atria have small pockets within them where static blood, normally ejected with contraction, allows clots to form. These emboli can break off, particularly with reversion and be ejected into the aorta. This allows high likelihood of the clot travelling upward into the brain. Anticoagulant drugs are used to minimize the risk of this happening

Atrial fibrillation can spontaneously appear and revert. It is a common rhythm for patients to briefly deteriorate into when hypothermic and post-return of spontaneous circulation.

Question 17

Atrial Fibrillation
rate/rhythm

Answer 17

Rate: will vary
Rhythm: Atrial (P-P): irregular / Vent. (R-R): irregular “regularly irregular”
P-Wave: many/non-discernable (absent however
may actually look like there are lots of different-looking P waves, known as the fibrillation baseline)
P-R Interval: <0.12/unmeasurable/ (<3 small squares)
QRS Complex: <0.12sec (<3 small squares) can be narrow (the electrical activity is originating from the atria rather than the ventricles)
ST Segment: Level w isoelectric line
T-wave: rounded, slightly asymmetrical

Question 18

Junction rhythm
define

Answer 18

A junctional rhythm is when the electrical impulses are generated in the AV node rather than the SA node or surrounding tissues and travel retrogradely (moving backward) towards the atria and anterogradely (moving forward) towards the ventricles. The pathophysiology of a junctional rhythm involves a disruption in the normal cardiac conduction system, leading to an alternate pacemaker site taking over the role of the SA node.

Question 19

Junction rhythm
rate/rhythm ect.

Answer 19

Rate: 40 - 60 bpm
Rhythm: Vent. (R-R): regular
P-Wave: absent/hidden or inverted after QRS
P-R Interval: non-discernible / abnormal P waves
QRS Complex: <0.12sec (<3 small squares)
ST Segment: Level w isoelectric line
T-wave: rounded, slightly asymmetrical

Question 20

Accelerated junctional rhythm (AJR)
define

Answer 20

Accelerated junctional rhythm (AJR) is a type of arrhythmia that originates in the AV junction, specifically in the area of the AV node or the His-Purkinje system. The exact pathophysiology of AJR is not fully understood, but it is thought to be due to increased automaticity or triggered activity in the AV junctional tissue. Normally, the SA node is the primary pacemaker of the heart and controls the heart rate. However, in cases of AJR, the AV junctional tissue is able to generate electrical impulses at a faster rate than the SA node. This can occur due to several reasons such as an increase in sympathetic tone, electrolyte imbalances, or structural abnormalities in the heart.

Question 21

Accelerated junctional rhythm (AJR)
rate/rhythm ect.

Answer 21

Rate: 60 -100 bpm
Rhythm: Vent. (R-R): regular
P-Wave: absent/hidden or inverted after QRS
P-R Interval: non-discernible, very short if P wave present
QRS Complex: <0.12sec (<3 small squares) can be narrow
ST Segment: Level w isoelectric line
T-wave: rounded, slightly asymmetrical

Question 22

Junctional Tachycardia rhythm
define

Answer 22

Is a type of arrhythmia that originates in the AV junction, specifically in the area of the AV node or the His-Purkinje system. The exact pathophysiology of junctional tachy is not fully understood, but it is thought to be due to increased automaticity or triggered activity in the AV junctional tissue. Normally, the SA node is the primary pacemaker of the heart and controls the heart rate. However, in cases of junctional tachy , the AV junctional tissue is able to generate electrical impulses at a faster rate than the SA node. This can occur due to several reasons such as an increase in sympathetic tone, electrolyte imbalances, or structural abnormalities in the heart.

The QRS complexes are usually narrow and have a regular or slightly irregular rhythm, with a ventricular rate typically between 100-180 beats per minute.

Question 23

Junctional Tachycardia rhythm
rate/rhythm ect.

Answer 23

Rate: >100 bpm
Rhythm: Vent. (R-R): regular
P-Wave: absent/hidden or inverted after QRS
P-R Interval: non-discernible
QRS Complex: <0.12sec (<3 small squares), can be narrow
ST Segment: Level w isoelectric line
T-wave: rounded, slightly asymmetrical

Question 24

Junctional P waves
define the 3 and how

Answer 24

Junctional P waves
If the origin is close to the atria, they will still depolarise before the ventricles and the P wave will appear inverted before the QRS.

If the origin is further away, the ventricles will depolarise before the atria, and the P wave will appear inverted after the QRS.

If the ventricles and atria depolarise at a similar time, the P wave will be buried within the QRS and not visible.

Question 25

Av node re-entrant rhythms
define overall

Answer 25

The AV node has the role of slowing conduction between the atria and the ventricle to allow time for blood to flow and fill the chambers ready for ejection.

Within the AV node are fast and slow channels – these allow for variable conduction and repolarisation within the AV node itself. They also allow the potential for re-entrant rhythms.

A quickly arriving electrical impulse can arrive and trigger the faster repolarising cells in the AV node to set up a new QRS complex before the SA node is itself ready to go again. An atrial ectopic beat is an example of such a quickly arriving impulse

Question 26

Atrial re-entrant tachycardia
define

Answer 26

Atrial re-entrant tachycardia involves the impulse spreading from the AV node, through the ventricle and finding an aberrant way to return to the atria. This is usually via an accessory pathway. This allows it to travel a loop and return to the AV node before the SA node has fired again. It enters the AV node and stimulates the faster repolarising cells that are ready. In this fashion a rapid loop is established between AV node – aberrant channel – AV node again forming an SVT

Typically involves an accessory pathway outside the AV node. In AVRT, there is an abnormal conduction pathway that connects the atria and ventricles, bypassing the AV node. This accessory pathway can create a reentry circuit that causes the rapid heart rate characteristic of SVT

Question 27

Atrial re-entrant tachycardia
rate/rhythm ect.

Answer 27

Rate: 140-250
Rhythm: Vent. (R-R): irregular / regular
P-Wave: hidden, non-discernible
P-R Interval: unmeasurable
QRS Complex: <0.12sec (<3 small squares), a delta wave, which is an early upstroke of the QRS complex due to pre-excitation of the ventricles by an accessory pathway (bypassing AV)
ST Segment: Level w isoelectric line
T-wave: rounded, slightly asymmetrical

Question 28

AV nodal re-entrant tachycardia
define

Answer 28

The AV nodal re-entrant tachycardia is a fast channel repolarised and ready to conduct. It can trigger the slow channel thus setting up not only a new QRS, but also starting a loop within the AV node itself

In AVNRT, there is a reentry circuit within the AV node that allows electrical impulses to continuously cycle through it and cause a rapid heart rate

Question 29

AV nodal re-entrant tachycardia
rate/rhythm ect.

Answer 29

Rate: 150-250
Rhythm: Vent. (R-R): regular
P-Wave: hidden, non-discernible
P-R Interval: unmeasurable
QRS Complex: <0.12sec (<3 small squares), narrow
ST Segment: Level w isoelectric line
T-wave: rounded, slightly asymmetrical

Question 30

Idioventricular rhythm
define

Answer 30

Idioventricular rhythm is a cardiac rhythm in which the ventricles of the heart become the primary pacemaker, resulting in a slow and regular ventricular rate between 15-40 beats per minute. The pathophysiology of idioventricular rhythm is the abnormalities in the SA node (the SA node fails to generate an impulse or when the impulses from the SA node are blocked from reaching the ventricles).

The ventricular tissue has an increased ability to generate electrical impulses. There is a delay in the conduction of electrical impulses through the ventricles which leads to reentry. This leads to the QRS complex being wider than normal since origin within the ventricles means electrical current flow will not follow the most efficient bundle branch pathways and take longer to travel. Idioventricular rhythm (IVR) occurs when the SA and AV nodes are either NOT firing or firing slower than the ventricular pacemaker rate.

Question 31

Idioventricular rhythm
rate/rhythm ect.

Answer 31

Rate: 20-40bpm
Rhythm: Vent. (R-R): regular and slow
P-Wave: absent (or they may be dissociated from the QRS complexes, as the ventricles are the primary pacemaker and are not being activated by the atria)
P-R Interval: unmeasurable (no p-wave)
QRS Complex: >0.12sec (>3 small sq.) wide and bizarre, different shape (because the ventricles are being activated by a different conduction system than in normal sinus rhythm)
ST Segment: none
T-wave: deflection

Question 32

Accelerated idioventricular rhythm
define

Answer 32

Accelerated idioventricular rhythm (AIVR) is a type of ventricular arrhythmia characterized by a regular, wide complex rhythm with a ventricular rate of 40-100 beats per minute.
The pathophysiology of AIVR involves the presence of an ectopic focus (an excitable group of cells that causes a premature heart beat outside the normally functioning SA node of the heart) within the ventricles that fires at a faster rate than the normal sinus rhythm. This ectopic focus can arise from the Purkinje fibers or ventricular myocardium.

Occasionally the pacemaker of this rhythm will fire faster than this, particularly post reperfusion during myocardial infarction. Where idioventricular rhythm responds faster than the inherent 40 per minute, it is referred to as accelerated idioventricular rhythm. This is so right up until its rate is 100 per minute

Question 33

Accelerated idioventricular rhythm
rate/rhythm ect.

Answer 33

Rate: 40-100bpm
Rhythm: Vent. (R-R): regular
P-Wave: absent (as ventricular rhythm)
P-R Interval: unmeasurable (no p-wave)
QRS Complex: >0.12sec (>3 small sq.) wide and have a bizarre appearance due to the ventricular origin of the rhythm
ST Segment: none
T-wave: deflection

Question 34

Ventricular tachycardia (VT)
define

Answer 34

Ventricular tachycardia (VT) is a potentially life-threatening arrhythmia that originates from the ventricular myocardium (mussel tissue). The pathophysiology of VT is characterized by the presence of a reentry circuit within the ventricular tissue, which causes the electrical impulses to circulate repeatedly through the ventricles at a rapid rate, resulting in a wide QRS complex on the electrocardiogram (ECG).

Ventricular tachycardia is more than just simply accelerated idioventricular rhythm even faster. The rate of 100 per minute is carefully chosen when discussing the cut off point between one and the other

At 100 or less, the sinus node, at least in theory, can depolarise that quickly and remain the dominant pacemaker in the heart

The strategy to deal with that slower arrhythmia is then based on the fact that the SA node has not taken over and looking for ways to deal with it

With VT on the other hand, it is firing faster than the SA node will normally fire. In this case, the response strategy is to eradicate the VT and let the SA node have a chance to reassert itself.

If high in the ventricle and near the AV node, the QRS may point in a similar direction to the normal observed pathway in that lead. Conversely, if low in the ventricle Purkinje network, the QRS might appear to be entirely in the opposite direction

Question 35

Ventricular tachycardia (VT)
rate/rhythm ect.

Answer 35

Rate: >100bpm (101 - 250 bpm)
Rhythm: Vent. (R-R): regular and irregular
P-Wave: absent or not associated with the QRS
P-R Interval: unmeasurable (no p-wave)
QRS Complex: >0.12sec (>3 small sq.) wide and bizarre
ST Segment: none
T-wave: none

Question 36

Torsades de pointes (TdP)
define

Answer 36

Torsades de pointes (TdP) is a type of ventricular tachycardia (VT) characterized by a specific pattern of QRS complexes that twist around the baseline, giving the appearance of a “polymorphic” VT. The pathophysiology of TdP involves an abnormality in cardiac repolarization, specifically prolongation of the QT interval. In TdP, the prolonged repolarization creates a “vulnerable window” during which early afterdepolarizations (EADs) can occur. EADs are abnormal depolarizations that occur during the repolarization phase of the action potential, and can cause premature depolarization of the ventricles. When EADs occur in the presence of an early depolarization, they can trigger a reentrant arrhythmia that causes TdP. The twisting appearance of the QRS complexes in TdP is due to changes in the location of the area of depolarization within the ventricles, which occurs as the arrhythmia progresses.

Question 37

Torsades de pointes (TdP)
rate/rhythm ect.

Answer 37

Rate: >100bpm 150 - 300 bpm (normally between 200 and 250 beats per minute)
Rhythm: Vent. (R-R): regular
P-Wave: absent or not associated
P-R Interval: unmeasurable (no p-wave)
QRS Complex: >0.12sec (>3 small sq.) wide, bizarre (some deflecting downward, some deflecting upward)
ST Segment: none
T-wave: none

Question 38

Ventricular fibrillation (VF)
define

Answer 38

Ventricular fibrillation (VF) is a life-threatening cardiac arrhythmia in which the ventricles of the heart quiver or fibrillate instead of contracting properly. This results in an ineffective pumping of blood and can quickly lead to cardiac arrest and death if not treated immediately.
The pathophysiology of VF involves a chaotic electrical activity in the ventricles, which disrupts the normal coordinated contraction of the myocardium. It usually arises from the disorganized activation of multiple foci of electrical activity within the ventricles, which create a rapidly changing, irregular, and unpredictable wave pattern on the ECG.

Chaotic, disorganised, irregular
Rapid but with no identifiable P wave, PR interval, T wave. No prospect of a pulse

Question 39

Ventricular fibrillation (VF)
rate/rhythm ect.

Answer 39

Rate: not discernible, rapid
Rhythm: irregular, chaotic, unorganized, rapid
P-Wave: absent, not associated
P-R Interval: unmeasurable (no p-wave)
QRS Complex: not discernible (rapid, small, and irregular deflections)
ST Segment: none
T-wave: none

Question 40

premature atrial contraction (PAC)
define

Answer 40

A premature atrial contraction (PAC) is a type of cardiac arrhythmia that originates from an ectopic focus (abnormal pacemaker sites within the heart (outside of the SA node) that display automaticity) in the atria, causing an early depolarization of the atria before the next expected sinus beat. PACs may occur due to various reasons, including increased sympathetic activity, caffeine consumption, alcohol use, or underlying heart disease. When a PAC occurs, it generates a premature P wave on the electrocardiogram (ECG) that is typically different in morphology (interpretation/shape) from the sinus P wave, indicating that the impulse originated from a different part of the atria.

Abnormal P wave, originating at an ectopic pacemaker, followed usually by normal QRS

Question 41

premature atrial contraction (PAC)
rate/rhythm ect.

Answer 41

Rate: Underlying rhythm
Rhythm: Underlying rhythm regular; PAC: Irregular (The PAC interrupts the normal rhythm, causing a brief pause before the next sinus beat
or a compensatory pause followed by a shortened RR interval)
P-Wave: present, upright; appears earlier than expected PAC: abnormal size, shape, direction
P-R Interval: 0.12 - 0.20sec (3-5 small squares)
PAC: <0.12sec (<3 small sq.)
QRS Complex: <0.12sec (<3 small squares)
ST Segment: Level w isoelectric line
T-wave: rounded, slightly asymmetrical (In some cases, a PAC can cause changes in the T wave, including inversion or a tall, peaked T wave)

Question 42

Premature junctional contraction (PJC)
define

Answer 42

A premature junctional contraction (PJC) is a cardiac arrhythmia that occurs when the electrical impulse that initiates a heartbeat originates from the atrioventricular (AV) node or the tissue just above or below it, instead of the sinoatrial (SA) node. This results in a premature contraction of the atria or ventricles, depending on where the electrical impulse originates. The mechanism of PJC is similar to that of PAC, except that the electrical impulse originates from the AV node instead of the atria. The premature contraction may occur in a single beat or in a series of beats and can occur in people with or without underlying heart disease.

Originates at the AV node - P wave can be present, absent or ‘retrograde’
Usually followed by a normal QRS if normal conduction pathway used

Question 43

Premature junctional contraction (PJC)
rate/rhythm ect.

Answer 43

Rate: Underlying rhythm
Rhythm: Underlying rhythm regular; PJC: Irregularly Irregular
P-Wave: present, upright; PJC: inverted, before/ after or hidden by QRS
Following the PJC, there is a pause that is equal to twice the normal R-R interval.
P-R Interval: 0.12 - 0.20sec (3-5 small squares) PJC: <0.12sec (<3 small sq.)
QRS Complex: <0.12sec (<3 small squares)
ST Segment: Level w isoelectric line
T-wave: rounded, slightly asymmetrical

Question 44

Premature ventricular contractions (PVCs)
define

Answer 44

Premature ventricular contractions (PVCs) occur when the ventricles contract earlier than usual in the cardiac cycle, resulting in a premature heartbeat. This is due to the generation of an impulse in the ventricles that bypasses the normal electrical conduction system. PVCs can disrupt the normal rhythm of the heart, and frequent or sustained PVCs can increase the risk of more serious arrhythmias or cardiac complications.
Originating from a ventricular pacemaker, an extra beat with abnormally wide QRS – not using normal conduction pathway

Originating from a ventricular pacemaker, an extra beat with abnormally wide QRS – not using normal conduction pathway so is wide and in a different direction

Question 45

Premature ventricular contractions (PVCs)
rate/rhythm ect.

Answer 45

Rate: Underlying rhythm
Rhythm: Underlying rhythm regular; PVC: Irregular
P-Wave: present, upright; PVC: not associated,
before/ after/hidden by QRS
P-R Interval: 0.12 - 0.20sec (3-5 small squares)
PVC: not measurable
QRS Complex: <0.12sec (<3 small squares)
PVC: >0.12sec (>3 small sq.) wider and taller and occurs earlier than the next expected heartbeat
ST Segment: Level w isoelectric line
PVC: deflected
T-wave: rounded, slightly asymmetrical
PVC: deflected and in the opposite direction (inverted)

Question 46

escape beat
define

Answer 46

The pathophysiology of an escape beat involves a failure of the SA node to generate an action potential, which may be due to damage, ischemia, or other factors that disrupt the normal electrical activity of the heart. In response to this failure, a subsidiary pacemaker located further down the conduction system of the heart takes over (AV node, the bundle of His, or the Purkinje fiber) and generates an action potential, which then spreads through the myocardium to trigger a contraction of the heart. This helps to maintain cardiac output and prevent a potentially life-threatening decrease in blood pressure.

Question 47

escape beat
rate/rhythm ect.

Answer 47

Rate: Underlying rhythm
40-60 beats per minute (in the case of an AV nodal escape beat)
or 20-40 beats per minute (in the case of a His-Purkinje escape beat)
Rhythm: Underlying rhythm regular;
Escape Beat: Irregular
P-Wave: present, upright;
Escape Beat: dropped
P-R Interval: 0.12 - 0.20sec (3-5 small squares) Escape Beat: not measurable
QRS Complex: <0.12sec (<3 small squares)
Escape Beat: occurs late and wide >0.12sec (>3 small sq.)
ST Segment: Level w isoelectric line
Escape Beat: deflected
T-wave: rounded, slightly asymmetrical
Escape Beat: deflected

Question 48

bigeminy
define

Answer 48

When an ectopic beat occurs ‘every other beat’, it is called bigeminy. Bigeminy is a cardiac arrhythmia characterized by alternating normal beats and premature beats occurring in a repetitive pattern. The premature beats can originate from either the atria or the ventricles and are typically caused by an irritable focus in the heart that fires before the normal cardiac pacemaker. This results in the heart contracting too early and inefficiently, leading to a beat that is often weaker than a normal beat. The premature beat then triggers a compensatory pause before the next normal beat occurs, leading to the alternating pattern of normal and premature beats. Bigeminy can be caused by a variety of factors, including electrolyte imbalances, medications, heart disease, and stress.

Question 49

bigeminy
rate/rhythm ect.

Answer 49

Rate: Underlying rhythm (100 bpm)
Rhythm: Underlying rhythm regular;
Every 2nd QRS (PVC) early - Irregular
P-Wave: present, upright;
PVC: not associated, before/ after/hidden by QRS
P-R Interval: 0.12 - 0.20sec (3-5 small squares) PVC: not measurable
QRS Complex: <0.12sec (<3 small squares)
Every 2nd QRS (PVC) >0.12sec (>3 small sq.)
Every other beat is wide and bizarre; compensatory pause
ST Segment: Level w isoelectric line
PVC: deflected
T-wave: rounded, slightly asymmetrical
PVC: deflected

Question 50

salvo
define

Answer 50

When three or more ectopic beat occur in a row, it is called a salvo. A salvo rhythm is a type of cardiac arrhythmia that occurs when there is a group of three or more consecutive premature ventricular contractions (PVCs). The pathophysiology of a salvo rhythm is similar to that of PVCs, which occurs when there is an early electrical impulse originating from a ventricular site other than the normal conduction pathway in the heart, resulting in premature ventricular depolarization and contraction.

Question 51

salvo
rate/rythm ect.

Answer 51

Rate: Underlying rhythm regular (PVC: Variable and irregular)
Rhythm: Underlying rhythm regular; PVC: early - regular
P-Wave: present, upright;
PVC: not associated, before/ after/hidden by QRS
P-R Interval:0.12 - 0.20sec (3-5 small squares) PVC: not measurable
QRS Complex: <0.12sec (<3 small squares)
PVC: 3 or more >0.12sec (>3 small sq.) wide and bizarre
The PVCs are often preceded by a compensatory pause, resulting in a regular rhythm interrupted by the salvo of PVCs
ST Segment: Level w isoelectric line / PVC: deflected
T-wave: rounded, slightly asymmetrical / PVC: deflected

Question 52

Asystole
define

Answer 52

Asystole is the absence of electrical and mechanical activity in the heart. The pathophysiology of asystole involves a complete cessation of the heart’s electrical activity, which leads to the cessation of the heart’s mechanical activity. As a result, blood flow to vital organs is severely compromised, and the absence of circulation can rapidly lead to irreversible brain damage and death.

Question 53

Asystole
rate/rhythm ect.

Answer 53

Rate: Atrial (P-P): regular / Vent. (R-R): 0 bpm
Rhythm: Atrial (P-P): regular / Vent. (R-R): absent
P-Wave: if present, upright
P-R Interval: unmeasurable (no r-wave)
QRS Complex: absent
ST Segment: none
T-wave: none

Question 54

Agonal rhythm
define

Answer 54

Agonal rhythm, also known as agonal pulseless electrical activity (PEA), is a cardiac rhythm that occurs in the setting of severe cardiac dysfunction, often in the final stages of cardiac arrest. It is not a true rhythm, but rather a disorganized electrical activity that occurs in the absence of a coordinated cardiac contraction. The pathophysiology of agonal rhythm is not well understood, but it is thought to be caused by a combination of severe myocardial dysfunction, ischemia, and acidosis.
During agonal rhythm, the heart may generate electrical activity that is visible on an electrocardiogram (ECG), but there is no effective cardiac output or blood pressure. The ECG may show a variety of patterns, including a slow, wide QRS complex, or a flat or nearly flat line, which may represent asystole.

Question 55

Agonal rhythm
rate/rhythm ect.

Answer 55

Rate: <20bpm
Rhythm: Vent. (R-R): irregular
P-Wave: absent or not associated
P-R Interval: unmeasurable (no p-wave)
QRS Complex: >0.12sec (>3 small sq.) wide, bizarre and unrecognisable
ST Segment: none
T-wave: deflection

Question 56

sinus pause
define

Answer 56

A sinus pause occurs when the SA node, which is the natural pacemaker of the heart, fails to generate an electrical impulse for a brief period of time. During a sinus pause, the heart may skip a beat or two, causing a brief pause in the heart rate. A sinus pause usually lasts for only a few seconds and is often harmless, especially if it occurs infrequently. For Sinus pause <3 otherwise it is a sinus arrest.

Question 57

sinus pause
rate/rhythm ect.

Answer 57

Rate:60-100bpm
Rhythm: Regular, irregular during pause
P-Wave: present, upright, absent during pause
P-R Interval: 0.12 - 0.20sec / (3-5 small squares)
QRS Complex: <0.12sec (<3 small squares) absent during pause
ST Segment: slight depression
T-wave: rounded, slightly asymmetrical

Question 58

Sinus arrest
define

Answer 58

Sinus arrest is where the sinus pause extends for more than three missing beats, when the SA node fails to fire. The resulting pause is often NOT equal to the multiple of P-P intervals >3. Instead, often an escape pacemaker such as the AV junction will assume control of the heart. Sinus arrest is a more serious condition where the SA node fails to generate electrical impulses for a period, leading to a complete cessation of the heart’s electrical activity. This can result in a prolonged pause in the heart rate, often lasting for several seconds or even minutes.

Question 59

Sinus arrest
rate/rhythm ect.

Answer 59

Rate: 60-100bpm
Rhythm: Regular, irregular during pause
P-Wave: present, upright, absent during pause
P-R Interval: 0.12 - 0.20sec / (3-5 small squares)
QRS Complex: <0.12sec (<3 small squares) absent during pause
ST Segment: This example, slight depression
T-wave: rounded, slightly asymmetrical

Question 60

First-degree atrioventricular (AV) block
define

Answer 60

First-degree atrioventricular (AV) block is an arrhythmia where there is a constant delay in electrical impulse conduction through the AV node. It may not be serious and in many cases does not require treatment. The pathophysiology of first-degree heart block is related to a delay in the conduction of electrical impulses from the atria to the ventricles (PR). A prolonged transmission of the electrical impulse through the AV junction (AV node and the Bundle of His). The significant finding of this rhythm is a prolonged PR interval of more than .20 (one square) seconds.

Question 61

First-degree atrioventricular (AV) block
rate/rhythm ect.

Answer 61

Rate: underlying rhythm
Rhythm: Atrial (P-P): regular / Vent. (R-R): regular
P-Wave: present, upright
P-R Interval: >0.20sec (>5 small squares)
QRS Complex: <0.12sec (<3 small squares)
ST Segment: Level w isoelectric line
T-wave: rounded, slightly asymmetrical

Question 62

Second-degree, type 1 AV block (Wenckebach)
define

Answer 62

Second-degree, type 1 AV block (Wenckebach) is an arrhythmia with progressive lengthening (delay) of the PR intervals until a QRS complex fails to appear after a P wave (the AV node completely blocks the impulse from passing to the ventricles). The pathophysiology in second-degree heart block is, there is a delay in the conduction of the electrical impulses from the atria to the ventricles. This is due to a delay or blockage within the AV node.

Question 63

Second-degree, type 1 AV block (Wenckebach)
rate/rhythm ect.

Answer 63

Rate: underlying rhythm
Rhythm: Atrial (P-P): regular / Vent. (R-R): irregular with the dropped beat
P-Wave: present, upright, precede each QRS complex when they are present
P-R Interval: progressively lengthens until missed QRS
QRS Complex: <0.12sec (<3 small squares)
ST Segment: Level w isoelectric line
T-wave: rounded, slightly asymmetrical

Question 64

Second-degree, type II AV block (Mobitz type II)
define

Answer 64

Second-degree, type II AV block (Mobitz type II) is similar to type I except there is no progressive lengthening of the PR interval before the QRS is missed. Second degree heart block type 2 is a type of heart block in which some atrial impulses are not transmitted to the ventricles, resulting in occasional dropped beats. Unlike in type 1, the PR interval remains constant before the dropped beat. This is because the block is located below the level of the AV node, typically in the bundle branches or the His-Purkinje system. It may progress quickly to complete heart block and require prompt intervention.

Question 65

Second-degree, type II AV block (Mobitz type II)
rate/rhythm ect.

Answer 65

Rate: Atrial (P-P): 2 or more / Vent. (R-R): 1
Rhythm: Atrial (P-P): regular / Vent. (R-R): usually regular
P-Wave: present, upright
P-R Interval: >0.12 and consistent (>3 small squares) (more P waves than QRS)
QRS Complex: <0.12sec (<3 small squares) slightly wider than normal as this AV block involves part of the underlying bundle branch as well
ST Segment: Level w isoelectric line
T-wave: rounded, slightly asymmetrical

Question 66

Third-degree AV
define

Answer 66

Third-degree AV (or complete) block is the complete absence of conduction of electrical impulses through the AV node, bundle of His, or bundle branches. It is the most serious of AV blocks and may be transient or persist.
In third degree (complete) heart block, there is complete dissociation between the atria and ventricles, resulting in independent electrical activity of the two chambers. The atria and ventricles beat independently, and the ventricular rate is typically slower than the atrial rate. The key ECG characteristic of third degree heart block is a regular atrial rhythm with a ventricular rhythm that is slower and usually regular, but can also be irregular.

Question 67

Third-degree AV
rate/rhythm ect.

Answer 67

Rate: Atrial (P-P): 60-100 / Vent. (R-R): <60
Rhythm: Atrial (P-P): regular / Vent. (R-R): regular No relationship
P-Wave: present, upright (do not relate to the QRS)
P-R Interval: varies, inconsistent
QRS Complex: <0.12sec (<3 small squares) usually wider given its origin in the ventricles; may be normal if the point of origin is in the AV junction
ST Segment: Level w isoelectric line
T-wave: rounded, slightly asymmetrical

Question 68

Second-degree 2:1 and advanced AV block
define

Answer 68

Are arrhythmias caused by the defective conduction of electrical impulses through the AV node or the bundle branches or both. This produces an AV block characterized by regularly or irregularly absent QRS complexes, commonly producing an AV conduction ratio of 2:1, 3:1, or greater, with or without a bundle branch block. 2:1 and advanced AV blocks are not considered to be of the classic type I or type II AV block.

Question 69

A right bundle branch block (RBBB)
define

Answer 69

A right bundle branch block (RBBB) occurs when there is an obstruction in the right bundle branch of the heart’s electrical conduction system. The right bundle branch is responsible for transmitting electrical impulses from the atrioventricular node to the right ventricle. When this pathway is blocked or delayed, the impulse is forced to travel through the left bundle branch first before reaching the right ventricle, resulting in a characteristic pattern on the electrocardiogram (ECG). MORROW (“RR” right, QRS W shape) (V2)
The pathophysiology of RBBB is characterized by the delayed depolarization of the right ventricle due to the blockage of electrical impulses through the right bundle branch. The left ventricle is activated first, followed by the right ventricle, which results in a delay in the onset of the QRS complex.

Question 70

A right bundle branch block (RBBB)
rate/rhythm ect.

Answer 70

Rate: underlying rhythm
Rhythm: Atrial (P-P): regular / Vent. (R-R): regular
P-Wave: present, upright
P-R Interval: 0.12 - 0.20sec (3-5 small squares)
QRS Complex: >0.12sec (>3 small squares)
- RSR’ pattern in V1-3 (“M-shaped” QRS complex)
- Wide, slurred S wave in lateral leads (I, aVL, V5-6) resulting in a rabbit ear appearance.
ST Segment: Level w isoelectric line
T-wave: rounded, slightly asymmetrical (the ST-segment depression and T-wave inversion in leads V1 to V3, reflecting delayed ventricular depolarization)

Question 71

Left bundle Branch (LBBB)
define

Answer 71

(LBBB)
In a healthy heart, electrical signals start in the SA node in the right atrium, travel through the atria, and then pass through the AV node to reach the ventricles. The ventricles then contract, pushing blood out to the body. The left and right bundle branches are specialized structures that conduct the electrical signals to the left and right ventricles, respectively.

In left bundle branch block (LBBB), the electrical signals to the left ventricle are delayed or blocked as they travel through the left bundle branch. This results in the left ventricle contracting later than the right ventricle (delayed depolarization), which can cause a number of changes on the electrocardiogram (ECG).
WILLAM (“LL” left , QRS M shape) (V1)