Cardiac Rhythms
Practice strips
An opportunity to test your skills
Identify cardiac pacemakers and their role in the cardiac cycle.
Define parameters of normal in a cardiac cycle.
objectives
Apply systematic approach to identifying cardiac rhythms.
Identify cardiac rhythms.
Conduction:
Pacemakers are the sites where the electrical signal in the heart begins. The sinoatrial (SA) node is the heart's primary, or main, pacemaker. There are several backup pacemakers that take over if the SA Node isn't working properly.
Electrical Pathway
Atrial Ventricular AV Junction The AV junction is located between the AV Node and above where the left and right bundle branches separate. When the AV Junction is the pacemaker for the heart, the "normal" rate is 40-60 beats per minute. You may or may not see a P wave when the AV Junction is the heart's pacemaker. If the electrical signal does travel up to the atria from this pacemaker, the P wave appears inverted on the monitor. Many times, when the AV Junction is the pacemaker, the electrical signal doesn't make it to the atria and the P wave does not appear on the monitor at all. Conduction to the ventricles is "normal" so the QRS is narrow when the AV Junction is pacing the heart.
Click button again to close window.
AV Junction
Click button again to close window.
SA Node The main pacemaker of the heart, located in the right atrium. When it fires normally, the heart beats at a rate of 60-100 beats per minute. When it fires, P waves are visible on the ECG and the QRS complex is usually within normal limits.
Purkinje Fibers or Ventricular Conduction System This is the last option for pacemaker in the heart. When ventricular conduction is the heart's primary pacemaker, the heart beats at a "normal" rate of 20-40 beats per minute. On the monitor, you will never see a P wave when the ventricles are acting as the primary pacemaker for the heart. The electrical signal doesn't make it up to the atria. With ventricular conduction, the QRS is wide.
Click button again to close window.
Click each button to review the heart's pacemakers
Purkinje Fibers or Ventriclar Conduction
Interactive question
The ECG readout is the visualization of the electrical activity in the heart. Remember: electrical activity comes before the actual muscle contraction. The start of the P wave is the message, actual contraction of the atria happens about mid P wave.
ecg readout
Take a moment to review the graphic. Make sure to compare each image to its corresponding location (identified by number) in the cardiac cycle.
ECG Complex
Let's take a moment to review features of a normal ECG feature in one cardiac cycle. The cardiac cycle is one cycle (or wave) of depolarization and repolarization from the atria all the way through the ventricles. Click the buttons for more information about each key feature.
Baseline
PR Interval
QRS Complex
Text
Normal Values
Measurements help us define parameters for a normal sinus rhythm. They also helps us identify when a rhythm is not normal, and understand what part of the cardiac cycle is not normal.
Normal Values: - P Wave < 2.5mm height and < 0.11 seconds - PR interval between 0.12 - 0.20 seconds - QRS complex between 0.06 - 0.10seconds - ST segment - should return to baseline - T wave usually < 5mm height & smooth or rounded
To figure out what a particular cardiac rhythm is, use a systematic approach. Questions you should ask yourself are:
Systematic Process
1. Is the rhythm regular? 2. Are there P waves? 3. Are there QRS complexes? 4. Does every P wave have a QRS complex and vice versa? 5. How long is the PR interval (does it fall in the normal range)? 6. How wide is the QRS complex (does it fall in the normal range)? 7. Are there any abnormalities?
Our first step is to identify if a rhythm is regular. Why? Because rhythm regularity immediately narrows down the possible diagnoses. Determining whether an ECG rhythm is regular or irregular is the foundation of rhythm interpretation—it guides every subsequent step and helps quickly distinguish between life-threatening arrhythmias and benign variations.
REGULAR
Regularity
IRREGULAR
Assessing the presence of P waves helps to determine the pacemaker site.
If you DO have a P wave, look at your PR interval: -PR interval is between 0.12 and 0.2 seconds (e.g., looks normal), then your pacemaker is either the SA Node or in the Atria (** P wave is usually upright in lead II) - PR interval is less than 0.12 seconds (e.g. looks short), then your pacemaker is in the AV Junction (** P wave is usually inverted in lead II) If you DON'T have a P wave, look at your QRS complex: - QRS complex is < or = 0.1 seconds (e.g., looks normal), then your pacemaker is in the AV Junction - QRS complex is > 0.1 seconds (e.g. looks wide), then your pacemaker is in the Ventricles
P Waves, PRI, and QRS
If your rhythm is REGULAR, and you've evaluated the P Wave to determine the pacemaker site, look at the rate.
Evaluate Rate
Remember your "normal" values for each pacemaker site: - SA Node/Atrial 60-100 bpm - AV Junction 40 - 60 bpm - Ventricular 20 - 40 bpm
Refer to the chart to identify names.
Wait!
My rhythm is regular, I have P waves, but my PR interval is > 0.20 seconds.
That describes a First Degree Heart Block. It looks like normal sinus rhythm, it is regular, but there is a prolonged PR interval, which means the electrical signal from the atria to the ventricles is slower than "normal" but still passes through to the ventricles without interruption. First Degree Heart Block is often asymptomatic.
Let's Practice!
See if you can identify the rhythms over the next few screens.
Name the rhythm
Rationale
Name the rhythm
Rationale
Name the rhythm
Rationale
Name the rhythm
Rationale
Name the rhythm
Rationale
Name the rhythm
Rationale
Name the rhythm
Rationale
Name the rhythm
Rationale
Name the rhythm
Rationale
Name the rhythm
Rationale
Name the rhythm
Rationale
The next question in our systematic process involves the relationship between P waves and QRS complexes.
If you do NOT have an even number of P waves and QRS complexes on your strip then you have some type of block. You need to take a closer look and see if there is a trend. Does the PR interval get longer and longer until it drops a QRS complex? Second degree heart block, type 1 (also known as Wenckebach) Does the PR interval stay the same and then it fails to conduct a QRS complex? Second degree block, type 2 Are you unable to detect a pattern? Is there no relationship between P waves and QRS complexes? Third degree block
P Wave to QRS Ratio
Premature Beats
Finally, your job is to identify if there are any abnormalities. This usually requires more detailed detective work. Does your strip look essentially normal, but there are early beats? If your early beat has: - a P wave, then it originated in the atria and is a premature atrial contraction (PAC) - an inverted or absent P wave, but the QRS complex looks "normal" (e.g. narrow), then it originated in the AV Junction and is a premature junctional contraction (PJC) - no P wave and the QRS complex looks "wide and bizarre" then it originated in the ventricles and is a premature ventricular contraction (PVC)
PAC
ABnormalities
Atrial Irregularities
There are other irregular rhythms that originate in the atria that have distinct features: Atrial fibrillation - does not have P waves because the atria are "quivering" choatically. The ECG baseline reflects the disorganized electrical activity in the atria. Electrical conduction to the ventricles is sporadic, resulting in irregular QRS complexes/heart beats. *Atrial fibrillation may have a normal rate or may have Rapid Ventricular Response (RVR) which is a tachy arrhythmia (faster than normal rate). Atrial flutter - has a very characteristic sawtooth pattern of P waves. It is caused by an abnormal electrical circuit in the atria which causes it to contract 250-350 beats per minute. Ventricular contraction may also be faster than normal. Atrial flutter is a more organized rhythm than fibrillation.
Atrial Fibrillation
ABnormalities
Atrial Flutter
Ventricular Irregularities
Similarly, in a heart that doesn't have atrial conduction, you may find other ventricular abnomalities. It's important to keep in mind that if you see this, you need to consider immediate intervention. These rhythms are from a very sick heart. Ventricular tachycardia (V Tach) - is characterized by bizarre widened QRS complexes, no P waves and usually a rate over 100 beats per minute. It may be monomorphic (where all the waves look the same) or polymorphic. Torsades de Pointes (TdP) - is a specific type of ventricular tachycardia, with a characteristic "twisting" around the baseline. It can quickly degrade into V Fib and cause sudden cardiac death. Patients with Torsades are often treated with magnesium or electrocardioverson. Ventricular fibrillation (V Fib) - is characterized by a chaotic wave pattern and no pulse. The ventricles are quivering chaotically and will quickly degrade to asystole if untreated. Treatment is usually defibrillation. (Remember: V Fib needs D-fib)
Ventricular Tachycardia
ABnormalities
Torsades de Pointes
Ventricular Fibrillation
Abnormalities: Cardiac ischemia
T Wave Inversion
ST Segment Elevation
ST Segment Depression
T waves alone do not indicate an ischemic event, but if they are an ongoing condition, they represent a prior ischemic event. When present with ST depression, may indicate an acute ischemic event.
Non-STEMI involves a partial blockage of a coronary artery, and usually represents less extensive damage to the heart muscle. This may be treated with medication before considering reperfusion.
ST segment elevation is important to recognize. It is related to cardiac ischemia, indicates a complete vessel occlusion, and requires immediate intervention. Usually treated with a reperfusion procedure.
Beyond normal: Identifying Abnormal
There are many strategies to help identify the abnormal rhythm. One is to use an algorithm or flowchart such as the one shown here. Take a moment to review this flowchart, note the names for each abnormal rhythm and the parameters associated with each one.
Click here to view a more complete flowchart.
Click link to download either version of the flowchart
This algorithm provides a quick guide but note that it is not all inclusive. It doesn't address every abnormal rhythm.
There are additional resources to consult that you may find helpful. This one is from nurselabs.com.
Identifying abnormal
Click the link to open the Electrical Node Pacemaker Handout that we referenced earlier in this lesson or the EKG Interpretation Cheat Sheet from Nurselabs.com.
Let's Practice!
See if you can identify the rhythms over the next few screens.
Name the rhythm
Rationale
Name the rhythm
Rationale
Name the rhythm
Rationale
Name the rhythm
Rationale
Name the rhythm
Rationale
Name the rhythm
Rationale
Name the rhythm
Rationale
Name the rhythm
Rationale
Name the rhythm
Rationale
Name the rhythm
Rationale
Name the rhythm
Rationale
Name the rhythm
Rationale
Name the rhythm
Rationale
Name the rhythm
Rationale
Name the rhythm
Rationale
Name the rhythm
Rationale
Name the rhythm
Rationale
Name the rhythm
Rationale
Need more practice?
There are many resources available if you need more practice. Two suggestions: - Go to Vanderbilt's Learning Platform (like Learning Exchange) and enter arrhythmia or cardiac rhythm. - Go to the internet and search for cardiac rhythm, ECG (or EKG) practice strips, or cardiac rhythm strips. There are many great practice sites out there.
Thank you!
Click the X in the upper right corner to close lesson.
1. Is the rhythm regular? No2. Are there P waves? Yes 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? Yes 5. How long is the PR interval (does it fall in the normal range)? Normal 6. How wide is the QRS complex (does it fall in the normal range)? Normal 7. Are there any abnormalities? Yes - there is a premature beat This is an irregular rhythm with premature beats. The premature beat has P waves a normal QRS complex so it originates in the SA Node. This is a Premature Atrial Complex (PAC).
Baseline
When there is no electrical activity in the heart, a flat line appears on the ECG/EKG. Recognizing baseline is a key element for rhythm interpretation. It helps determine angle changes for proper measurements, recognition of positive and negative deflections, and the presence of elevation and depression.
1. Is the rhythm regular? Yes2. Are there P waves? No 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? No 5. How long is the PR interval (does it fall in the normal range)? No 6. How wide is the QRS complex (does it fall in the normal range)? Wide 7. Are there any abnormalities? No This is a regular rhythm without P Waves. The QRS complex is wide and bizarre. So the pacemaker for this rhythm is Ventricular. Consult your Pacemaker - Measurement - Heart Rate - Name reference. Based on this being a regular rhythm, originating in the Ventricles, and the rate, this is Accelerated Ventricular.
1. Is the rhythm regular? No2. Are there P waves? Yes 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? No 5. How long is the PR interval (does it fall in the normal range)? Not normal 6. How wide is the QRS complex (does it fall in the normal range)? Normal 7. Are there any abnormalities? Yes - there is a dropped beat This is an irregular rhythm with a dropped beat. The PR interval gets progressively longer in subsequent cardiac cycles until it fails to conduct a beat (no QRS). This is a Second Degree Block, Type 1.
ST Segment
ST Segment is the beginning of repolarization of the ventricles. Note that the position of the ST segment relative to the baseline is very important. In a healthy heart the ST segment returns to baseline. Deflection (either above or below the baseline) may indicate when there is damage to the heart, usually related to hypoxia or blocked circulation (like during a myocardial infarction / heart attack).
1. Is the rhythm regular? No2. Are there P waves? Yes 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? Yes 5. How long is the PR interval (does it fall in the normal range)? Normal 6. How wide is the QRS complex (does it fall in the normal range)? Normal 7. Are there any abnormalities? Yes - there is a premature beat This is an irregular rhythm with premature beats. The premature beat has P waves a normal QRS complex so it originates in the SA Node. This is a Premature Atrial Complex (PAC).
1. Is the rhythm regular? Yes2. Are there P waves? Yes 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? Yes 5. How long is the PR interval (does it fall in the normal range)? Normal 6. How wide is the QRS complex (does it fall in the normal range)? Normal 7. Are there any abnormalities? Yes - the ST segment is elevated (above baseline) This is a regular rhythm with ST Elevation. This is a patient with a myocardial infarction (heart attack) and they need immediate intervention to reduce the damage to the heart from ischemia. This is ST Elevation Myocardial Infarction (STEMI).
1. Is the rhythm regular? Yes2. Are there P waves? Yes 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? Yes 5. How long is the PR interval (does it fall in the normal range)? Normal 6. How wide is the QRS complex (does it fall in the normal range)? Normal 7. Are there any abnormalities? No This is a regular rhythm, with P waves. The QRS complex is normal (narrow). So the pacemaker for this rhythm is the SA Node. Consult your Pacemaker - Measurement - Heart Rate - Name reference. Based on this being a regular rhythm originating in the SA Node, and the rate, this is Sinus Tachycardia.
1. Is the rhythm regular? Yes2. Are there P waves? No 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? No 5. How long is the PR interval (does it fall in the normal range)? No 6. How wide is the QRS complex (does it fall in the normal range)? Normal 7. Are there any abnormalities? No This is a regular rhythm but there are no P Waves. The QRS complex is normal (narrow). So the pacemaker for this rhythm is the AV Junction. Consult your Pacemaker - Measurement - Heart Rate - Name reference. Based on this being a regular rhythm, originating in the AV Junction, and the rate, this is Junctional Rhythm.
1. Is the rhythm regular? Yes2. Are there P waves? No 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? No 5. How long is the PR interval (does it fall in the normal range)? No 6. How wide is the QRS complex (does it fall in the normal range)? Wide 7. Are there any abnormalities? Yes This is a regular rhythm without any P waves. The QRS complex is wide. So the pacemaker for this rhythm is Ventricular. Consult your Pacemaker - Measurement - Heart Rate - Name reference. Based on this being a regular rhythm, originating in the Ventricles, and the rate, this is Ventricular Tachycardia. Remember, this rhythm requires immediate intervention!
1. Is the rhythm regular? Yes2. Are there P waves? Yes - but they are inverted 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? Yes 5. How long is the PR interval (does it fall in the normal range)? No, it is shorter than normal 6. How wide is the QRS complex (does it fall in the normal range)? Normal 7. Are there any abnormalities? No This is a regular rhythm with inverted P Waves. The PR interval is shorter than normal but the QRS complex is normal (narrow). So the pacemaker for this rhythm is the AV Junction. Consult your Pacemaker - Measurement - Heart Rate - Name reference. Based on this being a regular rhythm, originating in the AV Junction, and the rate, this is Junctional Tachycardia.
1. Is the rhythm regular? Yes2. Are there P waves? Yes 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? Yes 5. How long is the PR interval (does it fall in the normal range)? Normal 6. How wide is the QRS complex (does it fall in the normal range)? Normal 7. Are there any abnormalities? No This is a regular rhythm with P waves. The QRS complex is normal (narrow). So the pacemaker for this rhythm is the SA Node. Consult your Pacemaker - Measurement - Heart Rate - Name reference. Based on this being a regular rhythm originating in the SA Node, and the rate, this is Sinus Tachycardia.
1. Is the rhythm regular? Yes2. Are there P waves? Yes 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? No 5. How long is the PR interval (does it fall in the normal range)? No 6. How wide is the QRS complex (does it fall in the normal range)? No 7. Are there any abnormalities? Yes This is a regular rhythm with P waves but wide QRS complex, There are more P waves than QRS complexes and no relationship between the two. This is a Third Degree Block.
1. Is the rhythm regular? No2. Are there P waves? Yes 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? No 5. How long is the PR interval (does it fall in the normal range)? Normal 6. How wide is the QRS complex (does it fall in the normal range)? Normal 7. Are there any abnormalities? Yes - there are early beats This is an irregular rhythm with premature beats. The premature beat does not have a P wave but has a normal QRS complex so it originates in the AV Junction. This is a Premature Junctional Complex (PJC).
1. Is the rhythm regular? Yes2. Are there P waves? Yes 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? Yes 5. How long is the PR interval (does it fall in the normal range)? Normal 6. How wide is the QRS complex (does it fall in the normal range)? Normal 7. Are there any abnormalities? No This is a regular rhythm with P Waves. The QRS complex is normal (narrow). So the pacemaker for this rhythm is the SA Node. Consult your Pacemaker - Measurement - Heart Rate - Name reference. Based on this being a regular rhythm, originating in the SA Node, and the rate, this is Normal Sinus Rhythm.
NOTE: This algorithm is for instructional purposes, it does not address all arrhythmias.
P Wave
P Wave is when depolarization starts in and passes through the atria. Remember - what you see on the ECG is the electrical signal. The atria actually contract approximately mid-way through the P Wave.
1. Is the rhythm regular? Yes2. Are there P waves? Yes 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? Yes 5. How long is the PR interval (does it fall in the normal range)? Normal 6. How wide is the QRS complex (does it fall in the normal range)? Normal 7. Are there any abnormalities? Yes - the ST segment is depressed below baseline This is an regular rhythm with P waves and narrow QRSs, but the ST segment is depressed. This is probably an Non-STEMI, with a partially occluded vessel. This is a ST Depression, NSTEMI.
T Wave
Ventricular repolarization is complete by the end of the T Wave and then ventricular relaxation (diastole) begins. There's a return to baseline after the T Wave, then the cardiac cycle begins again and repeats continuously.
1. Is the rhythm regular? Yes2. Are there P waves? Yes 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? Yes 5. How long is the PR interval (does it fall in the normal range)? Yes 6. How wide is the QRS complex (does it fall in the normal range)? Normal 7. Are there any abnormalities? No This is a regular rhythm with P waves. The QRS complex is normal (narrow). So the pacemaker for this rhythm is the SA Node. Consult your Pacemaker - Measurement - Heart Rate - Name reference. Based on this being a regular rhythm, originating in the SA Node, and the rate, this is Sinus Tachycardia.
1. Is the rhythm regular? Yes2. Are there P waves? Yes 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? Yes 5. How long is the PR interval (does it fall in the normal range)? Normal 6. How wide is the QRS complex (does it fall in the normal range)? Normal 7. Are there any abnormalities? Yes - the ST segment is elevated This is a regular rhythm with P waves and narrow QRS complex. The signal originates in the SA Node. This may be mistaken for normal sinus, but this patinet needs treatment. The ST Segment is elevated indicating ischemia. This is ST elevation myocardia infarction (STEMI). This patient needs an immediate intervention to reduce the amount of ischemic damage to the heart.
QRS Complex
QRS complex is when depolarization passes through the ventricles. Repolarization of the atria occurs somewhere within the QRS complex but is masked. Ventricular contraction occurs shortly into the QRS complex and lasts through repolarization (through the T wave).
1. Is the rhythm regular? No2. Are there P waves? No 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? No 5. How long is the PR interval (does it fall in the normal range)? No 6. How wide is the QRS complex (does it fall in the normal range)? Normal 7. Are there any abnormalities? The baseline is "fibrillating" This is an irregular rhythm with no obvious P waves but normal looking QRS complexes. The baseline looks variable and is fibrillating. This is atrial fibrillation.
1. Is the rhythm regular? No2. Are there P waves? Yes 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? No 5. How long is the PR interval (does it fall in the normal range)? Normal 6. How wide is the QRS complex (does it fall in the normal range)? Normal 7. Are there any abnormalities? Yes - there is a premature beat This is an irregular rhythm with premature beats. The premature beat does not have a P wave but has a normal QRS complex so it originates in the AV Junction. This is a Premature Junctional Complex (PJC).
1. Is the rhythm regular? Yes2. Are there P waves? No 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? No 5. How long is the PR interval (does it fall in the normal range)? No 6. How wide is the QRS complex (does it fall in the normal range)? Normal 7. Are there any abnormalities? No This is a regular rhythm, but no P waves are present. The QRS complex is normal (narrow). So the pacemaker for this rhythm is the AV Junction. Consult your Pacemaker - Measurement - Heart Rate - Name reference. Based on this being a regular rhythm, originating in the AV Junction, and the rate, this is Junctional Rhythm.
1. Is the rhythm regular? Yes2. Are there P waves? Yes 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? Yes 5. How long is the PR interval (does it fall in the normal range)? Normal 6. How wide is the QRS complex (does it fall in the normal range)? Normal 7. Are there any abnormalities? No This is a regular rhythm, with P waves. The QRS complex is normal (narrow). So the pacemaker for this rhythm is the SA Node. Consult your Pacemaker - Measurement - Heart Rate - Name reference. Based on this being a regular rhythm, originating in the SA Node, and the rate, this is Sinus Bradycardia.
1. Is the rhythm regular? Yes2. Are there P waves? No 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? No 5. How long is the PR interval (does it fall in the normal range)? No 6. How wide is the QRS complex (does it fall in the normal range)? Normal 7. Are there any abnormalities? No This is a regular rhythm but there are no P Waves. The QRS complex is normal (narrow). So the pacemaker for this rhythm is the AV Junction. Consult your Pacemaker - Measurement - Heart Rate - Name reference. Based on this being a regular rhythm, originating in the AV Junction, and the rate, this is Junctional Tachycardia.
1. Is the rhythm regular? No2. Are there P waves? Yes 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? No 5. How long is the PR interval (does it fall in the normal range)? Not normal 6. How wide is the QRS complex (does it fall in the normal range)? Normal 7. Are there any abnormalities? Yes - there is a dropped beat This is an irregular rhythm with a dropped beat. The PR interval gets progressively longer in subsequent cardiac cycles until it fails to conduct a beat (no QRS). This is a Second Degree Block, Type 1.
1. Is the rhythm regular? No2. Are there P waves? No 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? No 5. How long is the PR interval (does it fall in the normal range)? No 6. How wide is the QRS complex (does it fall in the normal range)? Wide 7. Are there any abnormalities? Yes This is an irregular rhythm with no P Waves and the QRS complex is wide and bizarre. There's also a pattern that looks like the waves are rotating or revolving around the baseline. This is Torsades de Pointes. This can quickly degrade to V Fib, so this patient needs an intervention.
1. Is the rhythm regular? No2. Are there P waves? No 3. Are there QRS complexes? No 4. Does every P wave have a QRS complex and vice versa? No 5. How long is the PR interval (does it fall in the normal range)? No 6. How wide is the QRS complex (does it fall in the normal range)? No 7. Are there any abnormalities? Yes - there are no P Waves or QRS Complexes This is an irregular rhythm with no organized beats. This ventricles are quivering without any organized electrical signal. This is a very sick heart that requires immediate life-saving measures. This is a Ventricular Fibrillation (V Fib), remember this is treated with D Fib.
1. Is the rhythm regular? No2. Are there P waves? No 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? No 5. How long is the PR interval (does it fall in the normal range)? No 6. How wide is the QRS complex (does it fall in the normal range)? Normal 7. Are there any abnormalities? The baseline is "fibrillating" This is an irregular rhythm with no obvious P waves but normal looking QRS complexes. The baseline looks variable and is fibrillating. This is atrial fibrillation.
1. Is the rhythm regular? Yes2. Are there P waves? Yes 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? No 5. How long is the PR interval (does it fall in the normal range)? No 6. How wide is the QRS complex (does it fall in the normal range)? No 7. Are there any abnormalities? Yes This is a regular rhythm with P waves but wide QRS complex, There are more P waves than QRS complexes and no relationship between the two. This is a Third Degree Block. This patient is severly bradycardic and probably symptomatic. This patient most likely needs a pacemaker intervention.
PR Interval
The PR interval is associated with the electrical impulse passing through the AV Junction to the ventricles. This measurement helps identify when/if there's a block (something that slows down or prevents the electrical signal from moving from the atria to the ventricles).
1. Is the rhythm regular? No2. Are there P waves? Yes 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? No 5. How long is the PR interval (does it fall in the normal range)? No 6. How wide is the QRS complex (does it fall in the normal range)? Normal 7. Are there any abnormalities? Yes - there are sawtooth patterned P waves This is an irregular rhythm, with multiple P waves that present in a sawtooth pattern. This is a Atrial Flutter.
1. Is the rhythm regular? Yes2. Are there P waves? No 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? No 5. How long is the PR interval (does it fall in the normal range)? No 6. How wide is the QRS complex (does it fall in the normal range)? Wide 7. Are there any abnormalities? No This is a regular rhythm, but no P waves are present. The QRS complex is wide and bizarre. So the pacemaker for this rhythm is Ventricular. Consult your Pacemaker - Measurement - Heart Rate - Name reference. Based on this being a regular rhythm originating in the Ventricles and the rate, this is Idioventricular.
1. Is the rhythm regular? No2. Are there P waves? Yes 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? No 5. How long is the PR interval (does it fall in the normal range)? Normal 6. How wide is the QRS complex (does it fall in the normal range)? Mixed, normal + wide and bizarre. 7. Are there any abnormalities? Yes - there is a premature beat with a wide QRS This is an irregular rhythm with premature beats. The premature beat does not have P waves and the QRS complex is wide so it originates in the Ventricles. This is a Premature Ventricular Complex (PVC).
Cardiac Rhythms-Practice Strips
VHRHC Education
Created on October 20, 2025
Start designing with a free template
Discover more than 1500 professional designs like these:
View
Smart Presentation
View
Practical Presentation
View
Essential Presentation
View
Akihabara Presentation
View
Pastel Color Presentation
View
Visual Presentation
View
Relaxing Presentation
Explore all templates
Transcript
Cardiac Rhythms
Practice strips
An opportunity to test your skills
Identify cardiac pacemakers and their role in the cardiac cycle.
Define parameters of normal in a cardiac cycle.
objectives
Apply systematic approach to identifying cardiac rhythms.
Identify cardiac rhythms.
Conduction:
Pacemakers are the sites where the electrical signal in the heart begins. The sinoatrial (SA) node is the heart's primary, or main, pacemaker. There are several backup pacemakers that take over if the SA Node isn't working properly.
Electrical Pathway
Atrial Ventricular AV Junction The AV junction is located between the AV Node and above where the left and right bundle branches separate. When the AV Junction is the pacemaker for the heart, the "normal" rate is 40-60 beats per minute. You may or may not see a P wave when the AV Junction is the heart's pacemaker. If the electrical signal does travel up to the atria from this pacemaker, the P wave appears inverted on the monitor. Many times, when the AV Junction is the pacemaker, the electrical signal doesn't make it to the atria and the P wave does not appear on the monitor at all. Conduction to the ventricles is "normal" so the QRS is narrow when the AV Junction is pacing the heart.
Click button again to close window.
AV Junction
Click button again to close window.
SA Node The main pacemaker of the heart, located in the right atrium. When it fires normally, the heart beats at a rate of 60-100 beats per minute. When it fires, P waves are visible on the ECG and the QRS complex is usually within normal limits.
Purkinje Fibers or Ventricular Conduction System This is the last option for pacemaker in the heart. When ventricular conduction is the heart's primary pacemaker, the heart beats at a "normal" rate of 20-40 beats per minute. On the monitor, you will never see a P wave when the ventricles are acting as the primary pacemaker for the heart. The electrical signal doesn't make it up to the atria. With ventricular conduction, the QRS is wide.
Click button again to close window.
Click each button to review the heart's pacemakers
Purkinje Fibers or Ventriclar Conduction
Interactive question
The ECG readout is the visualization of the electrical activity in the heart. Remember: electrical activity comes before the actual muscle contraction. The start of the P wave is the message, actual contraction of the atria happens about mid P wave.
ecg readout
Take a moment to review the graphic. Make sure to compare each image to its corresponding location (identified by number) in the cardiac cycle.
ECG Complex
Let's take a moment to review features of a normal ECG feature in one cardiac cycle. The cardiac cycle is one cycle (or wave) of depolarization and repolarization from the atria all the way through the ventricles. Click the buttons for more information about each key feature.
Baseline
PR Interval
QRS Complex
Text
Normal Values
Measurements help us define parameters for a normal sinus rhythm. They also helps us identify when a rhythm is not normal, and understand what part of the cardiac cycle is not normal.
Normal Values: - P Wave < 2.5mm height and < 0.11 seconds - PR interval between 0.12 - 0.20 seconds - QRS complex between 0.06 - 0.10seconds - ST segment - should return to baseline - T wave usually < 5mm height & smooth or rounded
To figure out what a particular cardiac rhythm is, use a systematic approach. Questions you should ask yourself are:
Systematic Process
1. Is the rhythm regular? 2. Are there P waves? 3. Are there QRS complexes? 4. Does every P wave have a QRS complex and vice versa? 5. How long is the PR interval (does it fall in the normal range)? 6. How wide is the QRS complex (does it fall in the normal range)? 7. Are there any abnormalities?
Our first step is to identify if a rhythm is regular. Why? Because rhythm regularity immediately narrows down the possible diagnoses. Determining whether an ECG rhythm is regular or irregular is the foundation of rhythm interpretation—it guides every subsequent step and helps quickly distinguish between life-threatening arrhythmias and benign variations.
REGULAR
Regularity
IRREGULAR
Assessing the presence of P waves helps to determine the pacemaker site.
If you DO have a P wave, look at your PR interval: -PR interval is between 0.12 and 0.2 seconds (e.g., looks normal), then your pacemaker is either the SA Node or in the Atria (** P wave is usually upright in lead II) - PR interval is less than 0.12 seconds (e.g. looks short), then your pacemaker is in the AV Junction (** P wave is usually inverted in lead II) If you DON'T have a P wave, look at your QRS complex: - QRS complex is < or = 0.1 seconds (e.g., looks normal), then your pacemaker is in the AV Junction - QRS complex is > 0.1 seconds (e.g. looks wide), then your pacemaker is in the Ventricles
P Waves, PRI, and QRS
If your rhythm is REGULAR, and you've evaluated the P Wave to determine the pacemaker site, look at the rate.
Evaluate Rate
Remember your "normal" values for each pacemaker site: - SA Node/Atrial 60-100 bpm - AV Junction 40 - 60 bpm - Ventricular 20 - 40 bpm
Refer to the chart to identify names.
Wait!
My rhythm is regular, I have P waves, but my PR interval is > 0.20 seconds.
That describes a First Degree Heart Block. It looks like normal sinus rhythm, it is regular, but there is a prolonged PR interval, which means the electrical signal from the atria to the ventricles is slower than "normal" but still passes through to the ventricles without interruption. First Degree Heart Block is often asymptomatic.
Let's Practice!
See if you can identify the rhythms over the next few screens.
Name the rhythm
Rationale
Name the rhythm
Rationale
Name the rhythm
Rationale
Name the rhythm
Rationale
Name the rhythm
Rationale
Name the rhythm
Rationale
Name the rhythm
Rationale
Name the rhythm
Rationale
Name the rhythm
Rationale
Name the rhythm
Rationale
Name the rhythm
Rationale
The next question in our systematic process involves the relationship between P waves and QRS complexes.
If you do NOT have an even number of P waves and QRS complexes on your strip then you have some type of block. You need to take a closer look and see if there is a trend. Does the PR interval get longer and longer until it drops a QRS complex? Second degree heart block, type 1 (also known as Wenckebach) Does the PR interval stay the same and then it fails to conduct a QRS complex? Second degree block, type 2 Are you unable to detect a pattern? Is there no relationship between P waves and QRS complexes? Third degree block
P Wave to QRS Ratio
Premature Beats
Finally, your job is to identify if there are any abnormalities. This usually requires more detailed detective work. Does your strip look essentially normal, but there are early beats? If your early beat has: - a P wave, then it originated in the atria and is a premature atrial contraction (PAC) - an inverted or absent P wave, but the QRS complex looks "normal" (e.g. narrow), then it originated in the AV Junction and is a premature junctional contraction (PJC) - no P wave and the QRS complex looks "wide and bizarre" then it originated in the ventricles and is a premature ventricular contraction (PVC)
PAC
ABnormalities
Atrial Irregularities
There are other irregular rhythms that originate in the atria that have distinct features: Atrial fibrillation - does not have P waves because the atria are "quivering" choatically. The ECG baseline reflects the disorganized electrical activity in the atria. Electrical conduction to the ventricles is sporadic, resulting in irregular QRS complexes/heart beats. *Atrial fibrillation may have a normal rate or may have Rapid Ventricular Response (RVR) which is a tachy arrhythmia (faster than normal rate). Atrial flutter - has a very characteristic sawtooth pattern of P waves. It is caused by an abnormal electrical circuit in the atria which causes it to contract 250-350 beats per minute. Ventricular contraction may also be faster than normal. Atrial flutter is a more organized rhythm than fibrillation.
Atrial Fibrillation
ABnormalities
Atrial Flutter
Ventricular Irregularities
Similarly, in a heart that doesn't have atrial conduction, you may find other ventricular abnomalities. It's important to keep in mind that if you see this, you need to consider immediate intervention. These rhythms are from a very sick heart. Ventricular tachycardia (V Tach) - is characterized by bizarre widened QRS complexes, no P waves and usually a rate over 100 beats per minute. It may be monomorphic (where all the waves look the same) or polymorphic. Torsades de Pointes (TdP) - is a specific type of ventricular tachycardia, with a characteristic "twisting" around the baseline. It can quickly degrade into V Fib and cause sudden cardiac death. Patients with Torsades are often treated with magnesium or electrocardioverson. Ventricular fibrillation (V Fib) - is characterized by a chaotic wave pattern and no pulse. The ventricles are quivering chaotically and will quickly degrade to asystole if untreated. Treatment is usually defibrillation. (Remember: V Fib needs D-fib)
Ventricular Tachycardia
ABnormalities
Torsades de Pointes
Ventricular Fibrillation
Abnormalities: Cardiac ischemia
T Wave Inversion
ST Segment Elevation
ST Segment Depression
T waves alone do not indicate an ischemic event, but if they are an ongoing condition, they represent a prior ischemic event. When present with ST depression, may indicate an acute ischemic event.
Non-STEMI involves a partial blockage of a coronary artery, and usually represents less extensive damage to the heart muscle. This may be treated with medication before considering reperfusion.
ST segment elevation is important to recognize. It is related to cardiac ischemia, indicates a complete vessel occlusion, and requires immediate intervention. Usually treated with a reperfusion procedure.
Beyond normal: Identifying Abnormal
There are many strategies to help identify the abnormal rhythm. One is to use an algorithm or flowchart such as the one shown here. Take a moment to review this flowchart, note the names for each abnormal rhythm and the parameters associated with each one.
Click here to view a more complete flowchart.
Click link to download either version of the flowchart
This algorithm provides a quick guide but note that it is not all inclusive. It doesn't address every abnormal rhythm.
There are additional resources to consult that you may find helpful. This one is from nurselabs.com.
Identifying abnormal
Click the link to open the Electrical Node Pacemaker Handout that we referenced earlier in this lesson or the EKG Interpretation Cheat Sheet from Nurselabs.com.
Let's Practice!
See if you can identify the rhythms over the next few screens.
Name the rhythm
Rationale
Name the rhythm
Rationale
Name the rhythm
Rationale
Name the rhythm
Rationale
Name the rhythm
Rationale
Name the rhythm
Rationale
Name the rhythm
Rationale
Name the rhythm
Rationale
Name the rhythm
Rationale
Name the rhythm
Rationale
Name the rhythm
Rationale
Name the rhythm
Rationale
Name the rhythm
Rationale
Name the rhythm
Rationale
Name the rhythm
Rationale
Name the rhythm
Rationale
Name the rhythm
Rationale
Name the rhythm
Rationale
Need more practice?
There are many resources available if you need more practice. Two suggestions: - Go to Vanderbilt's Learning Platform (like Learning Exchange) and enter arrhythmia or cardiac rhythm. - Go to the internet and search for cardiac rhythm, ECG (or EKG) practice strips, or cardiac rhythm strips. There are many great practice sites out there.
Thank you!
Click the X in the upper right corner to close lesson.
1. Is the rhythm regular? No2. Are there P waves? Yes 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? Yes 5. How long is the PR interval (does it fall in the normal range)? Normal 6. How wide is the QRS complex (does it fall in the normal range)? Normal 7. Are there any abnormalities? Yes - there is a premature beat This is an irregular rhythm with premature beats. The premature beat has P waves a normal QRS complex so it originates in the SA Node. This is a Premature Atrial Complex (PAC).
Baseline
When there is no electrical activity in the heart, a flat line appears on the ECG/EKG. Recognizing baseline is a key element for rhythm interpretation. It helps determine angle changes for proper measurements, recognition of positive and negative deflections, and the presence of elevation and depression.
1. Is the rhythm regular? Yes2. Are there P waves? No 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? No 5. How long is the PR interval (does it fall in the normal range)? No 6. How wide is the QRS complex (does it fall in the normal range)? Wide 7. Are there any abnormalities? No This is a regular rhythm without P Waves. The QRS complex is wide and bizarre. So the pacemaker for this rhythm is Ventricular. Consult your Pacemaker - Measurement - Heart Rate - Name reference. Based on this being a regular rhythm, originating in the Ventricles, and the rate, this is Accelerated Ventricular.
1. Is the rhythm regular? No2. Are there P waves? Yes 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? No 5. How long is the PR interval (does it fall in the normal range)? Not normal 6. How wide is the QRS complex (does it fall in the normal range)? Normal 7. Are there any abnormalities? Yes - there is a dropped beat This is an irregular rhythm with a dropped beat. The PR interval gets progressively longer in subsequent cardiac cycles until it fails to conduct a beat (no QRS). This is a Second Degree Block, Type 1.
ST Segment
ST Segment is the beginning of repolarization of the ventricles. Note that the position of the ST segment relative to the baseline is very important. In a healthy heart the ST segment returns to baseline. Deflection (either above or below the baseline) may indicate when there is damage to the heart, usually related to hypoxia or blocked circulation (like during a myocardial infarction / heart attack).
1. Is the rhythm regular? No2. Are there P waves? Yes 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? Yes 5. How long is the PR interval (does it fall in the normal range)? Normal 6. How wide is the QRS complex (does it fall in the normal range)? Normal 7. Are there any abnormalities? Yes - there is a premature beat This is an irregular rhythm with premature beats. The premature beat has P waves a normal QRS complex so it originates in the SA Node. This is a Premature Atrial Complex (PAC).
1. Is the rhythm regular? Yes2. Are there P waves? Yes 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? Yes 5. How long is the PR interval (does it fall in the normal range)? Normal 6. How wide is the QRS complex (does it fall in the normal range)? Normal 7. Are there any abnormalities? Yes - the ST segment is elevated (above baseline) This is a regular rhythm with ST Elevation. This is a patient with a myocardial infarction (heart attack) and they need immediate intervention to reduce the damage to the heart from ischemia. This is ST Elevation Myocardial Infarction (STEMI).
1. Is the rhythm regular? Yes2. Are there P waves? Yes 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? Yes 5. How long is the PR interval (does it fall in the normal range)? Normal 6. How wide is the QRS complex (does it fall in the normal range)? Normal 7. Are there any abnormalities? No This is a regular rhythm, with P waves. The QRS complex is normal (narrow). So the pacemaker for this rhythm is the SA Node. Consult your Pacemaker - Measurement - Heart Rate - Name reference. Based on this being a regular rhythm originating in the SA Node, and the rate, this is Sinus Tachycardia.
1. Is the rhythm regular? Yes2. Are there P waves? No 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? No 5. How long is the PR interval (does it fall in the normal range)? No 6. How wide is the QRS complex (does it fall in the normal range)? Normal 7. Are there any abnormalities? No This is a regular rhythm but there are no P Waves. The QRS complex is normal (narrow). So the pacemaker for this rhythm is the AV Junction. Consult your Pacemaker - Measurement - Heart Rate - Name reference. Based on this being a regular rhythm, originating in the AV Junction, and the rate, this is Junctional Rhythm.
1. Is the rhythm regular? Yes2. Are there P waves? No 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? No 5. How long is the PR interval (does it fall in the normal range)? No 6. How wide is the QRS complex (does it fall in the normal range)? Wide 7. Are there any abnormalities? Yes This is a regular rhythm without any P waves. The QRS complex is wide. So the pacemaker for this rhythm is Ventricular. Consult your Pacemaker - Measurement - Heart Rate - Name reference. Based on this being a regular rhythm, originating in the Ventricles, and the rate, this is Ventricular Tachycardia. Remember, this rhythm requires immediate intervention!
1. Is the rhythm regular? Yes2. Are there P waves? Yes - but they are inverted 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? Yes 5. How long is the PR interval (does it fall in the normal range)? No, it is shorter than normal 6. How wide is the QRS complex (does it fall in the normal range)? Normal 7. Are there any abnormalities? No This is a regular rhythm with inverted P Waves. The PR interval is shorter than normal but the QRS complex is normal (narrow). So the pacemaker for this rhythm is the AV Junction. Consult your Pacemaker - Measurement - Heart Rate - Name reference. Based on this being a regular rhythm, originating in the AV Junction, and the rate, this is Junctional Tachycardia.
1. Is the rhythm regular? Yes2. Are there P waves? Yes 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? Yes 5. How long is the PR interval (does it fall in the normal range)? Normal 6. How wide is the QRS complex (does it fall in the normal range)? Normal 7. Are there any abnormalities? No This is a regular rhythm with P waves. The QRS complex is normal (narrow). So the pacemaker for this rhythm is the SA Node. Consult your Pacemaker - Measurement - Heart Rate - Name reference. Based on this being a regular rhythm originating in the SA Node, and the rate, this is Sinus Tachycardia.
1. Is the rhythm regular? Yes2. Are there P waves? Yes 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? No 5. How long is the PR interval (does it fall in the normal range)? No 6. How wide is the QRS complex (does it fall in the normal range)? No 7. Are there any abnormalities? Yes This is a regular rhythm with P waves but wide QRS complex, There are more P waves than QRS complexes and no relationship between the two. This is a Third Degree Block.
1. Is the rhythm regular? No2. Are there P waves? Yes 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? No 5. How long is the PR interval (does it fall in the normal range)? Normal 6. How wide is the QRS complex (does it fall in the normal range)? Normal 7. Are there any abnormalities? Yes - there are early beats This is an irregular rhythm with premature beats. The premature beat does not have a P wave but has a normal QRS complex so it originates in the AV Junction. This is a Premature Junctional Complex (PJC).
1. Is the rhythm regular? Yes2. Are there P waves? Yes 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? Yes 5. How long is the PR interval (does it fall in the normal range)? Normal 6. How wide is the QRS complex (does it fall in the normal range)? Normal 7. Are there any abnormalities? No This is a regular rhythm with P Waves. The QRS complex is normal (narrow). So the pacemaker for this rhythm is the SA Node. Consult your Pacemaker - Measurement - Heart Rate - Name reference. Based on this being a regular rhythm, originating in the SA Node, and the rate, this is Normal Sinus Rhythm.
NOTE: This algorithm is for instructional purposes, it does not address all arrhythmias.
P Wave
P Wave is when depolarization starts in and passes through the atria. Remember - what you see on the ECG is the electrical signal. The atria actually contract approximately mid-way through the P Wave.
1. Is the rhythm regular? Yes2. Are there P waves? Yes 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? Yes 5. How long is the PR interval (does it fall in the normal range)? Normal 6. How wide is the QRS complex (does it fall in the normal range)? Normal 7. Are there any abnormalities? Yes - the ST segment is depressed below baseline This is an regular rhythm with P waves and narrow QRSs, but the ST segment is depressed. This is probably an Non-STEMI, with a partially occluded vessel. This is a ST Depression, NSTEMI.
T Wave
Ventricular repolarization is complete by the end of the T Wave and then ventricular relaxation (diastole) begins. There's a return to baseline after the T Wave, then the cardiac cycle begins again and repeats continuously.
1. Is the rhythm regular? Yes2. Are there P waves? Yes 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? Yes 5. How long is the PR interval (does it fall in the normal range)? Yes 6. How wide is the QRS complex (does it fall in the normal range)? Normal 7. Are there any abnormalities? No This is a regular rhythm with P waves. The QRS complex is normal (narrow). So the pacemaker for this rhythm is the SA Node. Consult your Pacemaker - Measurement - Heart Rate - Name reference. Based on this being a regular rhythm, originating in the SA Node, and the rate, this is Sinus Tachycardia.
1. Is the rhythm regular? Yes2. Are there P waves? Yes 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? Yes 5. How long is the PR interval (does it fall in the normal range)? Normal 6. How wide is the QRS complex (does it fall in the normal range)? Normal 7. Are there any abnormalities? Yes - the ST segment is elevated This is a regular rhythm with P waves and narrow QRS complex. The signal originates in the SA Node. This may be mistaken for normal sinus, but this patinet needs treatment. The ST Segment is elevated indicating ischemia. This is ST elevation myocardia infarction (STEMI). This patient needs an immediate intervention to reduce the amount of ischemic damage to the heart.
QRS Complex
QRS complex is when depolarization passes through the ventricles. Repolarization of the atria occurs somewhere within the QRS complex but is masked. Ventricular contraction occurs shortly into the QRS complex and lasts through repolarization (through the T wave).
1. Is the rhythm regular? No2. Are there P waves? No 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? No 5. How long is the PR interval (does it fall in the normal range)? No 6. How wide is the QRS complex (does it fall in the normal range)? Normal 7. Are there any abnormalities? The baseline is "fibrillating" This is an irregular rhythm with no obvious P waves but normal looking QRS complexes. The baseline looks variable and is fibrillating. This is atrial fibrillation.
1. Is the rhythm regular? No2. Are there P waves? Yes 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? No 5. How long is the PR interval (does it fall in the normal range)? Normal 6. How wide is the QRS complex (does it fall in the normal range)? Normal 7. Are there any abnormalities? Yes - there is a premature beat This is an irregular rhythm with premature beats. The premature beat does not have a P wave but has a normal QRS complex so it originates in the AV Junction. This is a Premature Junctional Complex (PJC).
1. Is the rhythm regular? Yes2. Are there P waves? No 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? No 5. How long is the PR interval (does it fall in the normal range)? No 6. How wide is the QRS complex (does it fall in the normal range)? Normal 7. Are there any abnormalities? No This is a regular rhythm, but no P waves are present. The QRS complex is normal (narrow). So the pacemaker for this rhythm is the AV Junction. Consult your Pacemaker - Measurement - Heart Rate - Name reference. Based on this being a regular rhythm, originating in the AV Junction, and the rate, this is Junctional Rhythm.
1. Is the rhythm regular? Yes2. Are there P waves? Yes 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? Yes 5. How long is the PR interval (does it fall in the normal range)? Normal 6. How wide is the QRS complex (does it fall in the normal range)? Normal 7. Are there any abnormalities? No This is a regular rhythm, with P waves. The QRS complex is normal (narrow). So the pacemaker for this rhythm is the SA Node. Consult your Pacemaker - Measurement - Heart Rate - Name reference. Based on this being a regular rhythm, originating in the SA Node, and the rate, this is Sinus Bradycardia.
1. Is the rhythm regular? Yes2. Are there P waves? No 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? No 5. How long is the PR interval (does it fall in the normal range)? No 6. How wide is the QRS complex (does it fall in the normal range)? Normal 7. Are there any abnormalities? No This is a regular rhythm but there are no P Waves. The QRS complex is normal (narrow). So the pacemaker for this rhythm is the AV Junction. Consult your Pacemaker - Measurement - Heart Rate - Name reference. Based on this being a regular rhythm, originating in the AV Junction, and the rate, this is Junctional Tachycardia.
1. Is the rhythm regular? No2. Are there P waves? Yes 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? No 5. How long is the PR interval (does it fall in the normal range)? Not normal 6. How wide is the QRS complex (does it fall in the normal range)? Normal 7. Are there any abnormalities? Yes - there is a dropped beat This is an irregular rhythm with a dropped beat. The PR interval gets progressively longer in subsequent cardiac cycles until it fails to conduct a beat (no QRS). This is a Second Degree Block, Type 1.
1. Is the rhythm regular? No2. Are there P waves? No 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? No 5. How long is the PR interval (does it fall in the normal range)? No 6. How wide is the QRS complex (does it fall in the normal range)? Wide 7. Are there any abnormalities? Yes This is an irregular rhythm with no P Waves and the QRS complex is wide and bizarre. There's also a pattern that looks like the waves are rotating or revolving around the baseline. This is Torsades de Pointes. This can quickly degrade to V Fib, so this patient needs an intervention.
1. Is the rhythm regular? No2. Are there P waves? No 3. Are there QRS complexes? No 4. Does every P wave have a QRS complex and vice versa? No 5. How long is the PR interval (does it fall in the normal range)? No 6. How wide is the QRS complex (does it fall in the normal range)? No 7. Are there any abnormalities? Yes - there are no P Waves or QRS Complexes This is an irregular rhythm with no organized beats. This ventricles are quivering without any organized electrical signal. This is a very sick heart that requires immediate life-saving measures. This is a Ventricular Fibrillation (V Fib), remember this is treated with D Fib.
1. Is the rhythm regular? No2. Are there P waves? No 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? No 5. How long is the PR interval (does it fall in the normal range)? No 6. How wide is the QRS complex (does it fall in the normal range)? Normal 7. Are there any abnormalities? The baseline is "fibrillating" This is an irregular rhythm with no obvious P waves but normal looking QRS complexes. The baseline looks variable and is fibrillating. This is atrial fibrillation.
1. Is the rhythm regular? Yes2. Are there P waves? Yes 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? No 5. How long is the PR interval (does it fall in the normal range)? No 6. How wide is the QRS complex (does it fall in the normal range)? No 7. Are there any abnormalities? Yes This is a regular rhythm with P waves but wide QRS complex, There are more P waves than QRS complexes and no relationship between the two. This is a Third Degree Block. This patient is severly bradycardic and probably symptomatic. This patient most likely needs a pacemaker intervention.
PR Interval
The PR interval is associated with the electrical impulse passing through the AV Junction to the ventricles. This measurement helps identify when/if there's a block (something that slows down or prevents the electrical signal from moving from the atria to the ventricles).
1. Is the rhythm regular? No2. Are there P waves? Yes 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? No 5. How long is the PR interval (does it fall in the normal range)? No 6. How wide is the QRS complex (does it fall in the normal range)? Normal 7. Are there any abnormalities? Yes - there are sawtooth patterned P waves This is an irregular rhythm, with multiple P waves that present in a sawtooth pattern. This is a Atrial Flutter.
1. Is the rhythm regular? Yes2. Are there P waves? No 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? No 5. How long is the PR interval (does it fall in the normal range)? No 6. How wide is the QRS complex (does it fall in the normal range)? Wide 7. Are there any abnormalities? No This is a regular rhythm, but no P waves are present. The QRS complex is wide and bizarre. So the pacemaker for this rhythm is Ventricular. Consult your Pacemaker - Measurement - Heart Rate - Name reference. Based on this being a regular rhythm originating in the Ventricles and the rate, this is Idioventricular.
1. Is the rhythm regular? No2. Are there P waves? Yes 3. Are there QRS complexes? Yes 4. Does every P wave have a QRS complex and vice versa? No 5. How long is the PR interval (does it fall in the normal range)? Normal 6. How wide is the QRS complex (does it fall in the normal range)? Mixed, normal + wide and bizarre. 7. Are there any abnormalities? Yes - there is a premature beat with a wide QRS This is an irregular rhythm with premature beats. The premature beat does not have P waves and the QRS complex is wide so it originates in the Ventricles. This is a Premature Ventricular Complex (PVC).