Cardiac Rhythm Disturbances (Johsnton) Flashcards
What drugs/electrolytes are associated with bradycardia?
Digitalis, quinidine, hyperK
Drugs used for HTN to inhibit sympathetic tone –> clonidine, methyldopa, reserpine
B blockers
HR __ with inspiration
HR __ with expiration
Increases
Decreases
Can cause sinus arrhythmia and waxes/wanes with phases of respiration
Describe the following components of bradycardia:
- P wave:
- Rate:
- PR interval
P wave of sinus origin (normal axis)
Rate < 60/min
Constant and normal PR interval (.12-.20 sec)
Sinus bradycardia is commonly seen in ___, especially in the 1st few hrs. This is related to sinus node ischemia or to a vagal reflex initiated in ischemic area
Acute inferior MI
To tx bradycardia with hemodynamic compromise/unstable acute situations, use:
Atropine- .3–> .5 , 1 mg–> 2 mg IV, repeate 10 min
___ is a property of a cardiac cell to depolarize spontaneously during phase 4 of action potential/leads to generation of an impulse
Automaticity
___ are seen in absence of significant heart disease, is associated with stress, alcohol, tobacco, coffee, COPD, and CAD
Atrial arrhythmias, PAC
Describe the QRS with a PAC with aberrant ventricular conduction
Wide QRS
Describe the QRS in a non-conducted PAC
No QRS
How can you tx PACs if symptomatic?
Reverse causes
Beta blocker
Metoprolol 25-50 mg BID-TID
___ is a sudden HR greater than 100, usually rate of 150-250/min
Paroxysmal Atrial Tachycardia
Identify the “irritable focus”; P’ wave
In PAT with AV block, you will have ___ P’ wave/QRS complex and should suspect ___ toxicity
2 P’ waves for each QRS (2:1 ratio of P’:QRS) –> rapid rate, spiked P’ waves
Digitalis
Describe the following components of Multifocal Atrial Tachycardia:
- Amount of P waves
- PR interval
- Ventricular rhythm
- Atrial rate
3 or more different P waves
PR interval varies
Irregular ventricular rhythm
Atrial rate > 100
Should see at least 3 consecutive P waves with varying morphologies present with a rate over 100/min
Multifocal Atrial Tachycardia is associated with:
COPD/pneumonia/Ventilator theophylline Beta agonists Electrolyte abnormalities (decreased K and Mg) Digitalis toxicity Sepsis
How can you tx MAT?
CCB –> Non-DHP such as Diltiazem IV and Verapamil IV (avoid if EF <40%)
MgSO4 IV
Caution with B blockers
What are some etiologies of sinus tachycardia?
Emotion, anxiety, fear, drugs, hyperthyroid, fever, pregnancy, anemia, CHF, hypolvolemia
Physiologic/pathologic process
Describe the following components of A Fib:
- Atrial rate
- Baseline
- P waves
- ventricular rhythm
Atrial rate > 350-600/min
Undulating baseline
No discernible P waves
“Irregularly irregular” ventricular rhythm –> irregular RR interval (QRS complex)
What does A flutter look like on EKG? Which leads are they often best seen? Whats the rate>
“Saw tooth appearance”
Leads II, III, aVF, V, often best leads
250-350/min
A junctional automaticity focus may cause retrograde atrial depolarization. What does each P’ wave look like in leads with an upright QRS?
Inverted P’ waves
Describe the following components in Paroxysmal Junctional Tachycardia:
- Rate
- P waves
Rate 150-250/min
P wave may be lost (buried), inverted before or after each QRS
Describe the P waves in AV Nodal Re-entrant Tachycardia
No P waves
Describe the following components of Premature Ventricular Contraction’s:
- QRS complex
- P wave
Premature, bizarre, Wide QRS
No preceding P wave; may produced a retrograde P wave in ST segment
The ST-T wave moves in opposite direction of QRS
Usually full compensatory pause
What are some drugs/sources that can cause ventricular rhythm disturbances?
Nicotine Caffeine Thyroid Aminophylline Digitalis intoxication
What usually happens after a premature ventricular contraction?
Compensatory pause
