8 Arrhythmias- Clinical aspects Flashcards
What is this EKG showing?
Atrial fibrillation
What are some possible complications from atrial fibrillation?
Blood stasis in the atrium can lead to thrombus formation with risk of embolization and stroke
Patients with AF have 5x risk of stroke!!
How do you treat atrial fibrillation?
- anticoagulation
- acute at time of cardioversion
- chronic based on CHADSVasc score
- rate control
- beta blocker
- Ca channel blocker
- digoxin
- restoration of sinus rhythm
- carioversion
- antiarrhythmic drugs
- catheter ablation
What are the criteria of the CHADSVASc score?
- Congestive heart failure
- Hypertension
- Age >75 (2 points)
- Diabetes
- Stroke (2 points)
- Vascular disease
- Age >65
- Sex Category (female= 1 point)
**0= no therapy, 1= aspirin or oral anticoagulant, 2+ = oral anticoagulant
What is the benefit of NOACs over warfarin?
Decreased stroke risk (significant decrease in hemorrhagic strokes specifically)
What do you expect to find on EKG post versus pre initiation of sotalol?
Heart rate slowed and QTc interval prolonged (can lead to EADs and/or Torsades de pointes)
What are 5 factors that can contribute to torsades de pointes?
- sotalol
- acute renal insufficiency
- hypokalemia
- hypomagnesemia
- azithromycin
How do you treat torsades des pointes?
- Shock if sustained
- Supplement electrolyte imbalances if nonsustained (will stop on its own)
What is this EKG showing?
SVT (no clear P wave/atrial activity, it’s hidden within the QRS)
What is the most common cause of SVT?
AVNRT (typically slow pathway is antegrade and retrograde reentrant circuit is over the fast pathway)
What is “concealed” AVRT?
When an AP conducts only retrograde (can still promote SVT), but it’s “concealed” because signal travels antegrade down the AV node/bundle of His as normal
What is ventricular pre-excitation syndrome?
When the AP conducts antegrade in AVRT, creating a delta wave on EKG due to the early excitation of the ventricle through the AP
**e.g. WPW
What is the difference between orthodromic and antidromic tachycardia?
- orthodromic= retrograde conduction down AP (concealed)
- antidromic= antegrade conduction down AP (delta wave)
What is the valsalva effect?
- Forceful expiration against closed glottis
- Increases intrathoracic pressure -> increased external pressure on heart and thoracic vessels -> vagal efferents stimulated -> slows heart
- changes in HR are reciprocal to aortic pressures due to baroreceptor reflex
- Used as an easy first attempt to correct reentrant SVT
What is a common medication used to treat SVT?
Adenosine
**rapid acting, short lived/short decrease in HR
What is the mechanism of adenosine?
Activates K channels to slow phase 4 depolarization in AV node and block cAMP enhanced Ca channel activity
**overall blocks AV node conduction
What is this EKG showing?
Monomorphic V tach (typically wide QRS, rate >100 bpm)
What classifies sustained VT?
Ventricular tachycardia lasting longer than 30 seconds… shock to treat
What are some predisposing conditions to VT?
- coronary disease (with ischemia/infaction)
- congestive heart failure
- ventricular hypertrophy
- primary electrical disorders (e.g. long QT syndrome)
- valvular disease
- congenital heart disease
What is monomorphic VT? What can cause it?
- QRS complexes identical from beat to beat and rate is regular
- sustained monomorphic VT typically results from reentry due to slowed conduction through surviving myocardial cells within areas of myocardial scar
What is polymorphic VT? What can cause it?
- QRS complex continually changes shape and rate varies from beat to beat
- Caused by…
- long QT with Torsades de pointes
- acute ischemia/infarction
- rare inherited abnormalities of cardiac ion channels/Ca handling
**may cause syncope/cardiac arrest if sustained
How do you clinically manage VT?
**sustained VT= BAD (may degenerate into V fib)
- acute therapy for unstable patient
- cardioversion
- acute therapy for stable patient
- antiarrhythmic drugs (amiodarone)
- sedate/cardioversion
- long term
- determine/correct aggravating factor
- implantable cardioverter defibrillator (ICD)
- maybe antiarrhythmic drugs or VT ablation
What’s a major side effect of amiodarone?
- long half life and high volume of distribution allows accumulation of metabolite desethylamiodarone
- accumulates in…
- lungs (usually)
- liver, thyroid, nerves and skin
What is this EKG showing?
Atrial flutter
**regular 2:1 atrial: ventricular depol and sawtooth pattern
How do you treat atrial flutter?
- similar to atrial fibrillation treatment (including anticoagulants and cardioversion to correct rhythm)
- long term therapy=
- ablation between the tricuspid annulus and IVC
- antiarrhythmic drugs (flecanide)
- A fib results ~50% of the time after atrial flutter ablation
What is the common cause of atrial flutter?
Reentry around the tricuspid annulus in the right atrium
**typically counterclockwise rotation
