SA Node Electrical Impulses Beats per minute
60-100 BPM
AV Node Electrical Impulses Beats per minute
40-60 BPM
Bundle of His Electrical Impulses Beats per minute
40 -55 BPM
Bundle Branches Electrical Impulses Beats per minute
25-40 BPM
Purkinje Fibers Electrical Impulses Beats per minute
25-40 BPM
What is going on during one cardiac cycle?
P Wave = Atrial Depolarization
QRS complex = Ventricular Depolarization and masked Atrial Repolarization
T wave = Ventricular Repolarization
The QT interval is the vulnerable period for dysthrymias!
How much is one small box on EKG graph paper?
0.04 seconds
How much is one large box on EKG graph paper?
5 small boxes and = 0.20 seconds
How much is 5 large boxes on EKG graph paper?
1 second
How much is 30 large boxes on EKG graph paper?
6 seconds
What is a normal PR Interval?
0.12-0.20 seconds, from the beginning of the P wave to the beginning of the QRS
What is a normal QRS Complex?
Less than or equal to 0.12 seconds,
Narrow
Normal Sinus Rhythm characteristics
- Rate: 60–100 (ventricular and atrial)
- Rhythm: regular
- P waves: uniform and upright
- P to QRS Ratio: 1:1
- PR Interval: 0.12–0.20 seconds
- QRS Complex: less than 0.12 seconds
What causes sinus bradycardia?
- Lower metabolic needs: such as sleep, athletic training, hypothermia
- Vagal stimulation: such as vomiting, suctioning, severe pain, bowel movements
- Medications: such Calcium channel blockers, Beta-blockers
- Other: increased intracranial pressure, coronary artery disease, inferior wall MI, decompensated heart failure
Sinus Bradycardia Rhythm characteristics
- Rate: less than 60bpm in the adult (ventricular and atrial)
- Rhythm: regular
- P waves: Normal and consistent, in front of QRS
- P to QRS Ratio: 1:1
- PR Interval: Consistent, between 0.12–0.20 seconds
- QRS Complex: less than 0.12 seconds
What are the signs of sinus bradycardia?
Altered mental status
Hypotension
Chest discomfort
What is treatment for sinus bradycardia?
Correct the cause:
Think STOP MEDS, WARM pt, STOP Nausea or Vomiting
If the patient is symptomatic
give Atropine 0.5 mg IV via bolus. Repeat this every 3-5 minutes with a max dose of 3 mg
If atropine is ineffective:
Transcutaneous pacing
Dopamine or Epinephrine
Sinus Tachycardia Rhythm characteristics
- Rate: Greater than 100 bpm in the adult, usually less than 120 (ventricular and atrial)
- Rhythm: regular
- P waves: Normal and consistent, in front of QRS, may be buried in the preceding T
- P to QRS Ratio: 1:1
- PR Interval: Consistent, between 0.12–0.20 seconds
- QRS Complex: less than 0.12 seconds
What are the signs of sinus tachycardia?
- Dizziness
- Palpitations
- Shortness of breath
- Nausea
- Lightheadedness
- Chest pain
- Syncope
What causes sinus tachycardia?
- Physiologic: Acute blood loss, anemia, shock, hypervolemia, hypovolemia, heart failure, pain, hypermetabolic states, fever, exercise
- Psychological stress: anxiety
- Medications: Cold meds-pseudoephedrine, NSAIDs, Bronchodilators-albuterol, ADHD-Ritalin & Adderall, antidepressants-Cymbalta, Thyroid meds-Synthroid, Antibiotics-Zithromax, Levaquin
- Stimulants: Caffeine, nicotine. Illicit drugs: Amphetamines, cocaine, ecstasy
- Enhanced automaticity of the SA node-inappropriate sinus tachycardia
- Autonomic dysfunction: Postural orthostatic tachycardia syndrome (POTS) POTS (tachycardic with position changes but no change to BP)
What is treatment for sinus tachycardia?
- Correct cause: give fluids, blood products, pain medications, reduce anxiety, discontinue meds or stimulants
If patient is unstable:
- Vagal maneuvers
- Carotid massage
- Gagging
- Valsalva maneuve
- Coughing
- Face in ice waterAdenocard (Adenosine)
- Adenocard (Adenosine
Dose 6 mg, 12 mg, 12 mg fast push rapid IVP
- Synchronized cardioversion
Synchonized shock