7: Dysrhythmias Flashcards
Arrhythmias- SA node
1: sunus bradycardia
2: sinus tachycardia
3: sinus dysrhythmia
4: sinus arrest
Normal Sinus rhythm
- there must always be a P wave
- the P wave should be a rounded shape
- each P wave should be the same shape
- each P wave should be followed by a QRS of normal morphology
- the P-R interval should be 3-5 small squares and constant
- the rhythm should be regular
Arrhythmias- Atria
1: wandering pacemaker
2: premature atrial contractions (PAC)
3: atrial tachycardia (AT)
4: Paroxysmal supraventricular tachycardia (PSVT)
- AVNRT
- AVRT
5: atrial flutter
6: atrial fibrillation
Arrhythmias- AV junction
1: junctional rhythm
2: premature junctional contractions
3: junctional ectopic tachycardia
Arrhythmias- Ventricles
1: ventricular escape complexes and rhythm
2: premature ventricular complexes
3: ventricular tachycardia
4: ventricular fibrillation
Arrhythmias- Conduction
1: AV blocks
- 1-4th degree blocks
2: Bundle branch blocks
- RBBB
- LBBB
- Hemi-blocks
dysrhythmia- dx
Holter monitor
-portable ECG recorder for 24hr recording- for arrhythmia that occur less than daily
Treadmill testing
-dysrhythmias exacerbated by stress
Electrophysiologic studies (EP)
-electrodes are placed inside the right atrium and ventricle using catheter
-dx of abnormal foci or tract, SA, AV node disorder, placement of permanent pacemaker
Sinus arrhythmia
Phasic variation of R-R interval with respiration
Heart rate increases during inspiration and decreases during expiration
Sinus arrest
Failure of sinus node to initiate impulse- normal rhythm followed by an absent P wave and an absent ORS causes -sick sinus syndrome -ischemia -digitalis toxicity -excess vagal tone
Sick sinus syndrome
causes: degenerative process damaging the sinus node
-Sarcoidosis
-Amyloidosis
-Chaga’s disease
-Cardiomyopathies
sx: sinus bradycardia, sinus arrest or SA block, alternating episodes of tachyarrhythmia and bradycardia
Tx: no tx for asymptomatic, permanent pacing for symptomatic pts
Wandering atrial pacemaker (WAP)
Transient shifts in location of dominant pacemaker
EKG
-continual changes in the P-wave morphology. P waves vary in size, shape, and directions
-at least 3 different P waves must be present
-varying P-R intervals
Tx: not needed
Multifocal atrial tachycardia (MAT)
WAP associated with tachycardia (>100bpm)
Narrow QRS complexes
causes
-cor pulmonale, digitalis toxicity, CAD, elderly
Atrial tachycardia (AT)
heart rate: 120-250bpm AV block (by adenosine) does not terminate tachycardia
Premature atrial complexes
Common and benign
Premature P wave (buried in the preceding T wave)
Paroxysmal supraventricular tachycardia (PSVT)
sudden onset, usually initiated by a premature beat and the arrhythmia stops abruptly
Could result in decreased CO, angina, hypotention, CHF
types
1: AV node reentry (AVNRT)- 90%
2: AV reentrant tachycardia (AVRT)
AVNRT- info
Slow AV nodal pathway for anterograde conduction and Fast AV nodal pathway for retrograde conduction
P-wave buried in QRS and not seen
-if P wave is seen: pseudo ‘r’ wave at the end of QRS complex in V1, V2; or pseudo ‘S’ waves maybe seen in LEAD II, III, aVF
-Tachycardia associated with prolongation of PR interval
AVNRT- management
Initial maneuvers -carotid sinus massage -gagging -valsalva maneuver If fails -Adenosine (DOC)** If hemodynamic compromise (hypotension) -DC cardioversion** Chronic -Beta blocker -Ca channel blockers -Class IC antiarrhythmics -Radiofrequency catheter ablation of slow tract
AVRT- info
AV node and 1 or more bypass tracts
Orthodromic tachycardia (narrow qrs complex tachycardia)
-anterograde via AV node and retrograde via accessory pathway
Antidromic tachycardia (wide qrs complex tachycardia)
-anterograde via accessory pathway and retrograde via bundle of His and AV node