Cardiopulm Unit 2 Electrocardiography Flashcards
What is Sinus Rhythm?
Any cardiac rhythm in which depolarizes of the cardiac muscle begins at the sinus node
Abnormal cardiac rates/rhythms can occur if what?
- The SA node fails to function normally (e.g., sinus bradycardia or tachycardia)
- Other pacemaker sites within the atria or ventricles (e.g., ectopic pacemakes) trigger depolarization
- Conduction of electrical impulses between the hearts atria and ventricles is delayed or interrupted (AV block)
- Abnormal conduction pathways are followed (e.g., accessory pathways between atria and ventricles)
What happens as the wave of depolarization moves toward a positive electroid?
A positive deflection is observed on the ECG
What happens as the wave of depolarization moves away from a positive electroid?
A negative deflection is observed on the ECG
What happens as the wave of depolarization moves perpendicular to the positive electroid?
An isoelectric deflection is observed on the ECG (i.e., a deflection with both positive and negative components)
Lead 1, “looks” at what aspect of the heart?
It looks at the lateral aspect of the heart
Lead 2, “looks’’ at what aspect of the heart?
The base of the heart
Lead 3, looks at what aspect of the heart?
The inferior medial aspect of the heart
What do precordial leads do?
The provide a view of the heart in the transverse plane
(Labled V1-V6)
In an ECG, what is a segment?
The region between two waves
In an ECG, what is an Interval?
A duration of time that includes one segment and one or more waves
What does the P wave represent?
Depolarization of both atria. The P wave is the first ECG Deflection
What is the P-R Interval?
This is the electrical transmission from the atria to the ventricles
This typically takes 0.12-0.20sec
What does the QRS Complex represent?
The QRS complex indicates ventricular depolarization
- The R wave is the initial positive deflection
- The Negative deflection before the R wave is the Q wave
- The negative deflection after the R wave is the S wave
This typically takes 0.06-0.10sec
What does the S-T segment and T wave represent?
Both represent Ventricular Repolarization
- The S-T segment extends from the S wave to the beginning of the T wave
- The T-wave represents the repolarization of both ventricles
What are the S-T segments and T wave sensitive indicators of?
They are sensitive indicators of the oxygen supply status of the ventricular myocardium
What does R-R Wave represent?
Ventricular Depolarization (Ventricular systole)
- The measurment between each R-R wave give you sense on how regular or irregular the rhythm is
What is Sinus Bradycardia?
This is characterized by a sinoatrial (SA) node discharge rate less than 60bpm with normal P waves and QRS complexes
When is Sinus Bradycardia normal in/at?
- Rest
- Sleep
- Well-trained athletes due to increased vagal tone and stroke volume
- With some medications (e.g., beta- or calcium channel-blockers)
What are some Pathologic Causes of Sinus Bradycardia?
- Depressed intrinsic SA node automaticity due to ischemic heart disease or cardiomyopathy
- Heart blocks
- Metabolic dysfunction (e.g., hypothyroidism)
- TBI and increased intracranial pressures (Cushings’ reflex)
What is important to know about Mild Sinus Bradycardia?
- Its usually asymptomatic and does not require treatment. More pronounced HR decline, usually in the setting of a pathological condition, could produce a fall in cardiac output with Sx of fatigue, light-headedness, confusion, and/or syncope
What is the significance of Symptomatic Sinus Bradycardia?
The key clinical question is whether the bradycardia caused the patients Sx, or some other illness is causing bradycardia
- All bradycardias that present with signs or symptoms (hypotension, signs of heart failure, ventricular arrhythmias) should be evaluated at a higher level of medical care
What is Sinus Tachycardia Characterized by? What does this often result from?
Its characterized by a sinoatrial (SA) node discharge rate greater than 100bpm with normal P waves and QRS complexes
- This most often results from increased sympathetic and/or decreased parasympathetic (vagal) tone
When is Sinus Tachycardia appropriate? When is it from a pathological conditions?
- Its appropriate in response to exercise (~10bpm per MET)
Pathological conditions such as:
- Fever
- Pain
- Infections
- Hypoxemia
- Hyperthyroidism
- Hypovolemia (e.g., hemorrhage, dehydration)
- Amenia
- Low Cardiac output
What might Sinus Tachycardia lead to? What signs should we look for?
If the heart rate is too high, cardiac output may fall due to the markedly reduced ventricular filling time. In these cases, look for signs of:
-Hypotension
-Acute Altered Mental status (AMS)
-Ischemic chest discomfort due to increasing myocardial oxygen demand but reduced coronary blood flow
-Acute Heart Failure
- In these cases, a higher level of medical attention is necessary in order to determine whether the patient’s tachycardia is producing hemodynamic instability and other S/S or whether the S/S are producing tachycardia
What is Supraventricular Tachycardia (SVT)?
Rapid heart rhythm originating above the hearts ventricles, typcially involving the atria or atrioventricular node
What are Ectopic beats/focus?
Areas where the heart contracts itself; outside the normal conduction pathway.
- They typically have weaker contractions
Supraventricular Tachycardia
What is Atrial Tachycardia?
Abnormal heart rhythm that is characterized by a series of three or more consecutive ectopic beats originating in the atria
Supraventricular Tachycardia
What is Atrial Flutter?
This is characterized by a rapid, organized, and regular atrial rhythm. It has a unique re-entrant circuit, usually in the right atrium, which leads to the classic “Sawtooth” patten seen on the ECG
- Usually has a rate of 250-350bpm
- Usually has more than 1 P wave before every QRS complex
Re-entrant Circuit: Self-sustaining electrical pathway in the heart in which the impulse continues to circle through the tissue, causing repeated stimulation and a rapid heartbeat
How can Atrial Flutter occur? What type of patients can this occur in?
The structural and functional changes to the atrial myocardium following an Myocaridal Infarction or other sources of myocardial injury (e.g., surgery) can alter normal electrial conduction paths and set up a reentrant circuit.
- Atrial flutters can occur in individuals with other pre-existing heart conditions (e.g., valvular disease, pericarditis), have renal failure, hypertension, or chronic lung disease
Supraventricular Tachycardia
Is Atrial Flutter Permanent?
This may be paroxysmal/transient, persisting (lasting days or weeks), or permanent.
Supraventricular Tachycardia
What is Atrial Fibrillation?
The most common type of Serious Arrhythmia. This is characterized by a very fast and disorganized atrail rhythm, resulting from multiple ectopic foci and/or multiple reentry circuits generating electrical impulses in a chaotic manner. This leads to irregular rhythm known as “irregularly irregular” pulse.
- Erratic quivering or twitching of the atrial muscle
How can you tell the difference between Atrial Flutter and Atrial Fibrillation?
- Atrial Flutter is a more organized and REGULAR atrial rhythm
- Atrial Fibrillation, has no true P waves are found. The AV node acts to control the most of the impulses that initiate QRS complex; therefore a totally irregularly irregular rhythm exist
Is this picture an example of Atrial Flutter or Atrial Fibrillation?
Atrial Fibrillation
- There are no true P waves
Is this picture an example of Atrial Flutter or Atrial Fibrillation?
Atrial Flutter
- The P waves are organized and in rhythm, it also makes a “Sawtooth” like pattern
What can Atrial Flutter and Atrial Fibrillation result in?
Although they are not, in and of themselves, considered lifethreatening, they can lead to serious and potentially life-threatening complications if not properly managed:
- Stroke risk due to blood stasis
- Induce heart failure via tachycardia-induced cardiomyopathy
During exercise with atrial fibrillation/flutter, the signs & symptoms that may develop will largely depend on:
Sx of both atrial flutter and atrial fibrillation will largely depend on underlying ventricular rate
Individuals with untreated atrial fibrillation are at risk for which of the following disorders?
Thromboembolic Events
What are the Medical Options for treating Atrial Flutter and Fibrillation?
Cardioversion: A medical procedure that aims to restore a normal heart rhythm
Medications:
- Rate control medications: Beta-blockers and calcium channel blockers
- Rhythm control medications: Antiarrhythmic drugs work by altering the electrical signals in the heart to maintian a normal rhythm
- Anticoagulant: Prevent the formation of blood clots in the heart
What is Premature Ventricular Contactions (PVC)?
This occurs when an ectopic focus (or foci, in the case of mulifocal PCVs) creates an impulse from somewhere in one of the ventricles. It occurs early in the cardiac cycle before the SA node actually fires
The QRS complex is wide and bizarre and occurs earlier than normal sinus beat would have occurred. There are no P waves.
- It is wide because of slow cell to cell connections rather than through the normal rapidly conducting His-Purkinje system
What may PVCs be an indication of?
Can be an indication of an underlying cardiac disorder and take on added significance in that case. In those cases, due to increased risk of life-threatening ventricular arrhythmias, placement of an implantable cardioverter-defibrillator (ICD) is typically recommended
- PVCs are common even among healthy people and are often asymptomatic and benign.
When are PVCs considered serious?
- When they are paired together
- When they are mulifocal in orgin
- When they are more frequent than 10 per minute at rest
- When they are more present in triplets or more
What is common with those patients with Atrial Flutters and Fibrillations when they exercise? What Sx can be exacerbated by exercise?
They may experience reduced exercise tolerance, becoming fatigued more quickly or find that their usual level of physical activity is more strenuous than before.
- Sx like palpitations, SOB, or even chest pain can be exacerbated by exercise
Those patients with Atrial Fibrillations, how should you capture their heart rate instead of using a Pulse Oximeter?
Pulse oximeters may not be accurate due to the irregular rhythm. Instead consider assessment of the physical pulse for a full minute.
- If unsure about the ability to take radial pulse, with the stethoscope assess it apically.
In this pic, what is the name of the ECG?
Trigeminy
- Theres a PVC every 3rd
In this pic, what is the name of the ECG?
Bigeminy
- There is a PVC everyother
In this pic, what is the name of the ECG?
Couplet
- Theres 2 PVCs in a row
In this pic, what is the name of the ECG?
Triplet
- There are 3 PVCs in a row
What is Ventricular Tachycardia (VT)?
This is defined as a series of three or more PVCs in a row.
What does Ventricular Tachycardia indicate? What Sx are usually involved?
It indicates increased irritability and is an emergency situation because cardiac output can be significantly diminished, as is the blood pressure. Sx usually involve lightheadedness and syncope
What can Ventricular Tachycardia progress to?
VT can be tolerated at lower HR, it is a highly dangerous arrhythmia because it can progress to Ventricular Fibrillation (VF), particularly in the setting of decreased myocardial contractility (e.g., after an MI)
How is Ventricular Fibrillation characterized by?
What can VF progress to?
- Erratic quivering of the ventricular muscle and a cessation of cardiac output
- VF can further deteriorate to asystole if not treated
What are AV Heart Blocks?
Disorders of the heart’s rhythm due to an obstruction - a block - in the electrical conduction system of the heart. There are 3 types of AV Blocks:
- First Degree
- Second Degree
- Third Degree
What is a First Degree AV Block?
A stable prolongation of the PR Interval to more than 200ms and represents delay in conduction at the level of the AV node
What is a Second Degree AV block, Type 1?
Mobitz Type 1 (Wenckebach): Progressive prolongation of the PR interval before an atrial impulse fails to stimulate the ventricle (e.g., a P wave is nonconducted and a QRS is dropped). Usually occurs at the level of AV node
What is a Second Degree AV block, Type 2?
Mobitz Type 2: Fixed PR interval with some P waves not conducted. Usually occurs below the bundle of His and may be a bilateral bundle branch block
What is a Third Degree AV block?
(Complete Block), Abesence of AV conduction (all P waves are nonconducted) and complete disassociation of the atrial and ventricular rhythms (ventricular rate less than atrial rate)
What is a Cardiac Rhythm assessment used for? What are some considerations for this?
To identify and understand common to life-threatening arrhythmias. A regular rhythm expected during exercise; changes in arrhythmia with activity require careful evaluation
- Considerations for decision-making:
–Is the arrhythmia new or changing with increased activity?
–Is the arrhythmia benign or life-threatening?
–Is the arrhythmia producing new or worsening Sx?
What does the ST segment represent?
The period between the end of ventricular depolarization and the beginning of ventricular repolarizaation
What can changes in the ST-segment indicate?
This can be crucial indicator of myocardial ischemia or injury
- Ischemia can also manifest as T-wave inversions or flattening
What does this picture represent when talking about the T-wave?
This is Ischmia, without subendocardial injury (i.e. necrosis of myocardium - cell death) can present as T-Wave Inversion
What does this picture represent when talking about the T-wave?
This is Ischmia, with subendocardial injury (i.e. necrosis of myocardium - cell death) can present as ST segment depression
With the ST Segment, what can Upsloping represent??
Upsloping ST Segment depression ≥ 2.00 mm may represent Myocardial Ischemia, especially in the presence of angina. However this reponse has a low positive predictive value; it is often categorized as equivocal
With the ST Segment, what can Downsloping represent?
Downsloping ST Segment Depression ≥ 1.00mm is a strong indicator of myocardial ischemia
What is a ST Segment depression at a low workload associated with?
This is associated with worse prognosis and increased likelihood for multivessel disease
With ST-Segment Depression, what should be present in order for it to be “Clinically meaningful”?
ST-Segment Depression should be present in at least 3 consecutive cardiac cycles within the same lead. The level of the ST-segment should be compared relative to the end of the PR segment
- Clinically significant ST-segment depression that occurs during Post-exercise recovery is an indicator of myocardial ischemia
What is the difference between ST-Segment Elevation and ST-Segment Depression?
ST-Segment elevation is generally considered a medical emergency requiring immediate intervention, whereas ST-Segment depression may or may not be immediately life-threatening depending on the clincial contex
- ST-Segmetn Elevation MORE STRONGLY correlates with myocardial injury that has extended through the full thickness of the myocardium (i.e., transmural - “across the wall”)
How do you know if there is a Pathologic Q wave?
When the Q wave is 0.06 second in duration wide (one small square on the ECG tracing) or is one-third the size (height and depth included) of the QRS complex, the Q wave is considered significant and indicative of a pathologic condition (it persists as a permanent electrocardiographic “scar” from infarction)
The date of the infarction is not able to be determined
What is the function of a Pacemaker?
These create an artificial electrical voltage difference between 2 electrodes
- Marked by a pacer spike on ECG
What are different conditions that use Pacemakers?
Pacemakers are used for a variety of conditions which include: Sick Sinus Sydrome, 2nd degree or complete heart block, cardiac denervation (after transplant), severe sinus rhythm, easily provoked angina, CHF
- Symptomatic Bradycardia is a common theme
When it comes to Pacemakes, what should the focus of the PT be?
PTs should be monitoring ECG, Sx, and BP at rest and during exercise and/or functional training
When montioring ECG, what are signs of Pacemaker Failure?
- Lack of Spike
- Spike in wrong location
What are some Post-Op Recautions with Pacemakers?
Immediately after permanent pacemake placement:
- Ipsilateral AROM should be < 90° for 4 weeks
- Arm sling may be used
What are Automatic Implantable Cardioverter Defibrillator (AICD/ICD) used for?
Used to manage uncontrollable, life-threatening ventricular arrythmias by sensing the heart rhythm and defibrillating the myocardium
- Knowing the discharge rate allows for safe prescription of exercise
–Stay ~20-30 bpm under this rate
With the AICD/IDC, what are some questions we should ask the patient before prescribing exercises?
- Do you know your precautions?
- Do you know you BPM limitations?
With the AICD/ICD, what is the LifeVest used for?
- This is increasingly used as bridge to AICD placement or heart transplant
- Gives a warning alarm
After a diagnosis of ventricular tachycardia, a patient has an ICD implanted. The purpose of the ICD is to:
Prevent sudden death due to Ventricular Tachycardia
In general, Arrythmias that increase in frequency or complexity with progressive activity/exercise are associate with what?
Associated with Ischemia or with Hemodynamic instability, these are more likely to cause a poor outcome than isolated arrhythmias
In general, Frequent and Complex Ventricular Ectopy during exercise, especially in recovery is associated with what?
Associated with increased risk for Cardiac Arrest
This ECG is an example of what?
A. Ventricular Tachycardia
B. Ventricular Fibrillation
C. Atrial Flutter
D. Sinus Tachycardia
D. Sinus Tachycardia
This ECG is an example of what?
A. Ventricular Fibrillation
B. Atrial Fibrillation
C. Atrial Flutter
D. Sinus Tachycardia
B. Atrial Fibrillation
This ECG is an example of what?
A. 3rd degree Heart Block
B. Couplet
C. Sinus Bradycardia
D. Asystole
C. Sinus Bradycardia
This ECG is an example of what?
A. Atrial Flutter
B. Atrial Fibrillation
C. 2nd degree Heart Block, Type 1
D. Premature Ventricular Contraction (PVC)
A. Atrial Flutter
“Sawtooth” presentation
This ECG is an example of what?
A. Ventricular Tachycardia
B. Triplet
C. Bigeminey
D. Premature Ventricular Contraction (PVC)
D. Premature Ventricular Contraction (PVC)
This ECG is an example of what?
A. Ventricular Fibrillation
B. Ventricular Tachycardia
C. Asystole
D. Atrial fibrillation
B. Ventricular Tachycardia
This ECG is an example of what?
A. Ventricular Fibrillation
B. Ventricular Tachycardia
C. Asystole
D. Atrial fibrillation
A. Ventricular Fibrillation
This ECG is an example of what?
A. Ventricular Fibrillation
B. Ventricular Tachycardia
C. Asystole
D. Atrial fibrillation
C. Asystole
Can you “shock” or defibrillate someone in Asystole?
No, only if they are in V-Fib or V-Tach
What type of Heart block is shown in this ECG?
A. 1st degree AV heart block
B. 2nd degree Type 1
C. 2nd degree Type 2
D. 3rd degree (complete block)
A. 1st degree AV heart block
What type of Heart block is shown in this ECG?
A. 1st degree AV heart block
B. 2nd degree Type 1
C. 2nd degree Type 2
D. 3rd degree (complete block)
B. 2nd degree Type 1
What type of Heart block is shown in this ECG?
A. 1st degree AV heart block
B. 2nd degree Type 1
C. 2nd degree Type 2
D. 3rd degree (complete block)
C. 2nd degree Type 2
What type of Heart block is shown in this ECG?
A. 1st degree AV heart block
B. 2nd degree Type 1
C. 2nd degree Type 2
D. 3rd degree (complete block)
D. 3rd degree (complete block)
This ECG is an example of what?
A. Normal Sinus Rhythm
B. Sinus Bradycardia
C. Pacemaker
D. 1st degree heart block
C. Pacemaker
