Arrhythmias Flashcards
Sinus bradycardia etiology
Normal response to CV conditioning
Can also result from sinus node dysfunction or from B-blocker or CCB excess.
Signs/Symptoms of Sinus brady
May be Asx. May present with lightheadedness, syncope, chest pain or hypotension
ECG findings in sinus brady
Sinus rhythm
Ventricular rate less than 60bpm
Tx for sinus brady
None if ASx
Atropine may be used to increase HR
Pacemaker placement is the definitive tx in severe cases.
First degree AV block etiology
Can occur in normal individuals
Associated with increased vagal tone and with B-blocker or CCB use
Signs of First degree AV Block
Asx
ECG findings for First degree AV block
PR interval greater than 200ms
Tx for First degree AV block
None needed
Second degree AV block (Mobitz I/Wenckebach) etiology
Drug effects (Digoxin, B-blockers, CCBs) or increased vagal tone; R coronary ischemia or infarction
Mobitz I signs
Usually ASx
ECG findings for Mobitz I
Progressive PR lengthening until a dropped beat occurs; the PR interval then resets
Tx for Mobitz I
Stop offending drugs
Atropine as clinically indicated
Second degree AV block (Mobitz II) etiology
Results from fibrotic disease of the conduction system or from acute, subacute, or prior MI
Signs of Mobitz II
Occasionally syncope
Frequent progression to third-degree block
ECG findings of Mobitz II
Unexpected dropped beats without a change in PR
Tx for Mobitz II
Pacemaker placement
Third degree AV block (complete) etiology
No electrical communication between the atria and ventricles
Signs of complete heart block
Syncope, dizziness, acute heart failure, hypotension, cannon A waves
ECG for complete heart block
No relationship between P waves and QRS complexes
Tx for complete heart block
Pacemaker placement
Sick sinus syndrome/tachycardia-bradycardia syndrome etiology
A heterogeneous disorder that leads to intermittent SVT and bradyarrhythmias
Signs and symptoms of SSS
Secondary to tachycardia or bradycardia; may include syncope, palpitations, dyspnea, chest pain, TIA, and stroke
Sinus tachycardia etiology
Normal physiologic response to fear, pain, and exercise
Can be secondary to hyperthyroid, volume contraction, infection, or Pulm Embolus
This is supraventricular at Atria
Sinus tachycardia signs
Palpitations, SOB
ECG sinus tachy
Sinus rhythm, ventricular rate above 100bpm
Tx of sinus tachy
treat underlying cause
AFib etiology
Acute = PIRATES.
1) Pulmonary disease
2) Ischemia
3) Rheumatic heart disease
4) Anemia/Atrial myxoma
4) Thyrotoxicosis
5) Ethanol
6) Sepsis
Chronic - HTN and CHF
This is supraventricular at the atria
Signs of AFib
Often ASx, but may present with SOB, CP or palpitations
Physical exam reveals an irregularly irregular pulse
ECG AFib
No discernible P waves, with variable and irregular QRS response
Tx for AFib
Estimate risk of stroke using CHADS2 score. Anticoagulate if at or above 2.
Anticoagulation if more than 48h (to prevent CVA); rate control (B-blockers, CCBs, digoxin)
Initiate cardioversion only if new onset (less than 48h) or TEE shows no LA clot. OR after 3-6w of warfarin tx with a satisfactory INR of 2-3.
Atrial Flutter etiology
Another SVT with atrial origin
Circular movement of electrical activity around the atrium at a rate of approximately 300 times per minute
Signs of Atrial flutter
Usually ASx, but can present with palpitations, syncope, and lightheadedness
ECG for Atrial flutter
Regular rhythm; “sawtooth” appearance of P waves can be seen. The atrial rate is usually 240-320bpm and the ventricular rate is about 150 bpm
Treatment of Atrial flutter
Anticoagulation, rate control, and cardioversion guidelines just like in AFib
Multifocal atrial tachycardia etiology
Another SVT with atrial origin
Multiple atrial pacemakers or reentrant pathways; COPD, hypoxemia
Signs of MAT
May be ASx.
At least 3 different P-wave morphologies
ECG for MAT
3 or more unique P wave morphologies
Rate above 100bpm
Tx of MAT
Treat underlying disorder
Verapamil of B-blockers for rate control and suppression of atrial pacemakers (not very effective)
AV nodal reentry tachycardia (AVNRT) etiology
an SVT with AV junction origin
A reentry circuit in the AV node depolarizes the atrium and ventricle nearly simultaneously
Signs of AVNRT
Palpitations, SOB, Angina, Syncope, lightheadedness
ECG for AVNRT
Rate 150-250bpm
P wave is often buried in QRS or shortly after**
Tx of AVNRT
Cardiovert if hemodynamically unstable.
Carotid massage, valsalva, or adenosine can stop the arrhythmia
Atrioventricular reciprocating tachycardia (AVRT) etiology
an SVT with AV junction etiology
An ectopic connection between the atrium and ventricle that causes a reentry circuit. Seen in WPW.
Signs of AVRT
Palpitations, SOB, Angina, Syncope, lightheadedness
ECG for AVRT
A retrograde P wave is often seen after a normal QRS.
A preexcitation delta wave is characteristically seen in WPW
Tx for AVRT
Same as AVNRT
Paroxysmal atrial tachycardia
an SVT with AV junction origin
Rapid ectopic pacemaker in the atrium (not sinus node)
Signs of PAT
Palpitations, SOB, Angina, Syncope, lightheadedness
ECG for PAT
Rate over 100bpm
P wave with an unusual axis before each normal QRS
Tx for PAT
Adenosine can be used to unmask underlying atrial activity
Premature ventricular contraction etiology
a VT
Ectopic beats arise from ventricular foci. Associated with hypoxia, electrolyte abnormalities and hyperthyroidism
Signs of PVC
Usually ASx but may lead to palpitations
ECG for PVC
Early, wide QRS not preceded by a P wave
PVCs are usually followed by a compensatory pause
Tx for PVC
Treat underlying cause. If symptomatic give B-blockers or occasionally other antiarrhythmics
Ventricular tachycardia etiology
a VT (clearly)
Can be associated with CAD, MI, and structural heart disease
Signs of VTach
Nonsustained VT is often ASx
Sustained VT can lead to palpitations, hypotension, angina, and syncope
Can progress to VFib and death
ECG for VT
3 or more consecutive PVCs
Wide QRS complexes in a regular rapid rhythm
May see AV dissociation
Tx for VT
Cardioversion and antiarrhythmics (amiodarone, lidocaine, procainamide)
VFib etiology
a VT
Associated with CAD and structural heart disease. Also associated with cardiac arrest (together with asystole)
Signs of VFib
Syncope, absence of BP, pulselessness
ECG for VFib
Totally erratic wide-complex tracing
Tx for VFib
Immediate electrical cardioversion and ACLS protocol
Torsades de pointes etiology
a VT
Associated with long QT syndrome, proarrhythmic response to meds, hypokalemia, congenital deafness and alcoholism
Signs of Torsades
Can present with sudden cardiac death; typically associated with palpitations, dizziness, and syncope
ECG of Torsades
Polymorphous QRS; VT with rates between 150 and 250 bpm.
Tx for Torsades
Give magnesium initially and cardiovert if unstable
Correct hypokalemia
Withdraw offending drugs
