Dysrhythmias- Cardiovascular Nursing
This post will review the most common dysrhythmias that nursing students will need to know in order to be successful on their nursing school exams, the NCLEX examination, and in the clinical setting.
In this post we will be reviewing the following:
- Tachydysrhythmias
- Bradydysrhythmias
- Sinus tachycardia
- Sinus bradycardia
- Premature atrial complexes (PAC)
- Supraventricular tachycardia (SVT)
- Atrial fibrillation
- Premature ventricular complex (PVC)
- Ventricular tachycardia
- Ventricular fibrillation
- Asystole
- Pulseless electrical activity
- AV Blocks
For each dysrhythmia, we will explore the characteristics, causes, clinical manifestations, and treatments that you will need to know as a nursing student and future nurse.
Once you are done reading this post you can download the FREE study guide that contains all the important information in this post.
Brief Electrocardiogram (ECG or EKG) Review
Provides a graphic representation of the electrical activity of the heart
P wave- represents atrial depolarization- generated from the SA node
PR segment- from the end of the P wave to the beginning of the QRS complex- when the electrical impulse is travelling through the AV node
PR interval- measured from the beginning of the P wave to the end of the PR segment (0.12-0.20)
QRS complex- represents ventricular depolarization- QRS duration is the time required for depolarization of both ventricles (0.06-0.10 seconds)
ST segment- early ventricular repolarization
T wave- ventricular repolarization
U wave- may result from slow repolarization of ventricular Purkinje fibers
QT interval- represents the total time required for ventricular depolarization and repolarization
For a more in-depth review of the electrical conduction system of the heart, check out this video from MedCram:
Dr. Seheult has put together a whole ECG interpretation playlist together that you should definitely check out if you want some extra practice. You can find that playlist here.
Normal Sinus Rhythm (NSR)
Characteristics:
- 60-100 beats per minutes
- Atrial and ventricular rhythms are regular
- P waves are present with consistent configuration, one before each QRS complex
- PR interval- 0.12-0.20 seconds and constant
- QRS duration is 0.04-0.10 seconds and constant
Sinus arrhythmia
Variant of NSR; results from the change in intrathoracic pressure during breathing
Hear rate slightly increases with inspiration and decreases slightly during expiration
Charactersistics:
- 60-100 bpm
- Atrial and ventricular rhythms are irregular
- P waves are present with consistent configuration, one before each QRS complex
- PR interval is normal and constant
- QRS duration is normal and constant
Tachydysrhythmias
Characteristics:
- Heart rate is greater than 100 bpm
- Cardiac output and blood pressure begin to decrease
- Decreased coronary perfusion time
- Increased work of the heart
S/S:
- Palpitations
- Chest discomfort
- Restlessness and anxiety
- Pale, cool skin
- Syncope from hypotension
May lead to heart failure
Bradydysrhythmias
Characteristics:
- Heart rate is less than 60 bpm
- Myocardial oxygen demand is reduced
If heart rate is too slow, cardiac output may not be adequate
If blood pressure is adequate, the patient may be able to tolerate
If blood pressure is NOT adequate, it may lead to myocardial ischemia or infarction, dysrhythmias, hypotension, and heart failure
Premature Complexes
Occur when a cardiac cell or cell group, other than the SA node, fires an impulse before the next sinus impulse. This is called an ectopic focus
The patient may experience palpitations or may be unaware
May occur in a repetitively, rhythmic fashion
- Bigeminy- normal and premature complexes occur alternate in a repetitive two-beat pattern
- Trigeminy- repeated three-beat pattern– usually occurs as two normal complexes followed by a premature complex and a pause
- Quadrigeminy– four-beat pattern– usually occurs as three normal complexes followed by a premature complex and a pause
Sinus Dysrhythmias
Sinus tachycardia:
Characteristics:
- >100 beats per minute
- Decreased coronary perfusion
- Increased myocardial oxygen demand
Causes:
- May be normal physiologic response to activity such as exercise
- Anxiety
- Pain
- Stress
- Hypoxemia
- Hyperthyroidism
- Drugs- epinephrine, atropine, caffeine, alcohol
S/S:
- Patient may be asymptomatic
- Fatigue
- Weakness
- SOB
- Orthopnea
- Decreased oxygen saturation
- Decreased blood pressure
- Restlessness and anxiety- due to decreased cerebral perfusion
- Decreased urine output- due to impaired renal perfusion
Treatment:
- Treat underlying cause
Sinus bradycardia
Characteristics:
- <60 beats per minute
- Increased coronary perfusion time but may decrease coronary perfusion pressures
- Decreased myocardial oxygen demand
Causes:
- Valsava maneuvers
- Suctioning
- Vomiting
S/S
- May be asymptomatic
- Syncope
- Dizziness and weakness
- Confusion
- Decreased blood pressure
- Diaphoresis
- SOB
- Chest pain
Treatment:
- Treat underlying cause
- If cause cannot be determined- IV fluids, oxygen therapy
- Pacing may be needed
Atrial Dysrhythmias
Premature Atrial Complexes (PAC)
Occurs when atrial tissue becomes irritable
Causes:
- Anxiety
- Stress
- Fatigue
- Caffeine, nicotine, alcohol
- Myocardial ischemia
- Electrolyte imbalance
S/S
- Likely asymptomatic
- Palpitations
No intervention is needed unless there is a cause such as heart failure
Supraventricular tachycardia (SVT)
Rapid stimulation of atrial tissue at 100-280 beats per minute
May be intermittent or sustained
Sustained:
- Palpitations
- Chest pain
- Weakness
- Fatigue
- SOB
- Nervousness
- Anxiety
- Hypotension
- Syncope
Cardiac deterioration can occur and cause angina, heart failure, and cardiogenic shock
Nonsustained (intermittent)
- May be asymptomatic
- Occasional palpitations
Treatment:
- No intervention needed in a patient who is healthy and which SVT stops on its own
- Preferred treatment for recurrent SVT is radiofrequency catheter ablation
- Antidysrhythmic medications
Atrial fibrillation (A. Fib)
Associated with atrial fibrosis and loss of muscle mass
Multiple rapid impulses from the atria depolarize in a disorganized manner at a rate of 350 to 600 times per minute
Risk factors:
- Hypertension
- Previous ischemic stroke
- Transient ischemic attack
- Coronary artery disease
- Diabetes
- Heart failure
- Mitral valve disease
Characteristics:
- Chaotic rhythm
- No clear p waves
- No atrial contractions
- Loss of atrial kick
- Irregular ventricular response
- The atria simply quiver
- Decreased ventricular filling
- Decreased cardiac output
Thrombus formation can occur and increases the risk of stroke or other embolic events
S/S:
- Some patients may be asymptomatic
- Fatigue
- Weakness
- SOB
- Dizziness
- Anxiety
- Syncope
- Chest discomfort
Treatment:
- Antidysrhythmic drugs
- Calcium channel blockers- diltiazem, amiodarone, dronedarone
- Beta blockers- metoprolol and esmolol to slow ventricular response
- Digoxin for patients with A.Fib and heart failure
- Anticoagulants
- Heparin
- Enoxaparin (Lovenox)
- Warfarin (Coumadin)
- Cardioversion
- When drug therapy is not effective
- Anticoagulation for 6 weeks
- Transesophageal echocardiogram (TEE) before to check for atrial clots
- Other alternatives
- Percutaneous radiofrequency catheter ablation
- Biventricular pacing
- Surgical maze procedure (for patients with A. Fib and heart failure)
Ventricular Dysrhythmias
Premature Ventricular Complex (PVC)
Early ventricular complexes followed by a pause
Frequently occur in repetitive rhythms such as bigeminy or trigeminy
Can be insignificant or occur with issues such as MI, COPD, or chronic heart failure
S/S
- May be asymptomatic
- Palpitations
- Chest discomfort
- Decreased peripheral perfusion
Treatment:
- Eliminate contributing factors such as caffeine or stress
- Amiodarone and oxygen therapy can be used with acute myocardial ischemia
- Beta-blockers for severe cases (>5000 PVCs in a 24 hour period)
Ventricular Tachycardia (V. tach)
May be nonsustained or sustained
Causes:
- Ischemic heart disease
- MI
- Cardiomyopathy
- Hypokalemia
- Drug toxicity
V. tach is commonly the initial rhythm before V. fib in people who go into cardiac arrest
Manifestations partially depend on ventricular rate- slower rates are better tolerated
Treatment:
- Stable V. tach= elective cardioversion or antidysrhythmic drug such as mexiletine
- Unstable V. tach without pulse= same treatment as v. fib (see below)= DEFIBRILLATE
Ventricular fibrillation (V. Fib)
LIFE THREATENING!!
Characteristics:
- Ventricular contraction cannot occur
- Ventricles merely quiver
- NO cardiac output
- Life threatening if not ended within 3-5 minutes
Causes:
- MI
- Hypokalemia
- Hypomagnesemia
- Hemorrhage
- Rapid SVT
- Shock
- Surgery
- Trauma
S/S:
- Patient loses consciousness
- No pulse
- No breathing
- No blood pressure
- No heart sounds
- Seizures may occur
- Pupils become fixed and dilated
- Skin is cold and mottled
Treatment:
- DEFIBRILLATE
- If AED is not available, perform CPR until defibrillator arrives
- Airway management, oxygen therapy
- Drug therapy- vasopressin, epinephrine, amiodarone, lidocaine, magnesium sulfate
Asystole
Characteristics:
- No electrical activity
- No cardiac output
- No pulse
- No blood pressure
- No respirations
FULL CARDIAC ARREST
Treatment:
Do NOT shock– will not be effective
Drug therapy- epinephrine, atropine
*must be confirmed on two leads*
Pulseless electrical activity (PEA)
No pulse, but electrical activity on the screen may be sinus rhythm
Has underlying treatable cause
Causes:
| The 6 H’s | The 6 T’s |
| Hyperkalemia | Tamponade |
| Hypoxia | Tension pneumothorax |
| Hypothermia | Thrombosis (pulmonary embolus) |
| Hydrogen ion excess (acidosis) | Thrombosis (myocardial infarction) |
| Hypovolemia | Toxins |
| Hypoglycemia | Trauma |
Treat as without pulse- initiate CPR but do NOT shock
Treat underlying cause once the patient is stable
AV Blocks
Supraventricular impulses are block or delayed in the AV node or ventricular conduction system
- SA node continues to function normally
- P waves occur regularly
- QRS complex are delayed or blocked
1st degree- all sinus impulses eventually reach the ventricles
2nd degree- some sinus impulses reach the ventricles, but others are blocked
3rd degree- complete heart block- none of the sinus impulses reach the ventricles
Treatment:
- Oxygen
- Drug therapy
- Pacing/permanent pacemaker
NEED TO KNOW:
| Rhythm | Treatment |
| Ventricular tachycardia | Cardioversion Mexiletine |
| Pulseless ventricular tachycarida | DEFIBRILLATE |
| Ventricular fibrillation | DEFIBRILLATE (Defib the V.fib) |
| Pulseless Electrical Activity (PEA) | Initiate CPR DO NOT SHOCK |
| Asystole | Initiate CPR DO NOT SHOCK Meds- epinephrine, atropine |
That’s going to wrap up this information about dysrhythmias. I hope this was helpful for you.
Be sure to also check out my study tips, clinical guide, and other study material here on the site.
Happy Nursing!