Cardiology - Arrhythmias Flashcards
reversible causes of bradycardia?
#elevated intracranial pressure #hypothyroidism #hyperkalemia #Lyme disease #medications (beta-blockers, digoxin)
Most common INTRINSIC cause of pathologic sinus bradycardia? Extrinsic?
age-related myocardial fibrosis near the sinus node
medication effect
#R sided ischemia #intracranial hypertension #Post-surgical #Infiltrative/Inflammatory disease
Why is 1st degree AV block a problem?
#increased risk of afib #increased need for pacemaker #increased all-cause mortality
Heart block with generally benign prognosis?
Mobitz type I (wenckebach)
In patients with minimal symptoms, when are the (non-conduction block) indications for a permanent pacemaker?
#HR under 40 #Pauses over 3 seconds #AFib with 5 second pauses
When to place a pacemaker in patients with AV block?
#Asymptomatic complete heart block #Mobitz type 2 second-degree atrioventricular block #Alternating bundle branch block
This type of conduction abnormality only has a 1-3% chance of progression to complete AV block and therefore does not need a pacemaker?
Intraventricular conduction delay
All ICDs have pacemaker functions except?
subcutaneous ICDs
CRT-P vs CRT-D?
pacing only vs pacing/ATP/defibrillating
Only devices that can ATP?
non-subcutantous ICD and CRT-D
SVT with wide QRS complexes - differential?
#bundle branch block #aberrancy #pacing #anterograde accessory pathway conduction (antidromic trachycardia)
Antidromic tachycardia - mechanism?
accessory AV connection is used as the antegrade limb and the AV node or a second pathway serves as the retrograde limb of the circuit.
SVT arise from (with examples)?
Atrial - APCs, Afib, flutter, multifocal atrial tachycardia
ECG classification of SVTs?
short-RP (RP less than PR; P closely follows QRS) - typical AVNRT, AVRT, and junctional tachycardia
Maneuvers that can terminate SVTs?
#valsalva #carotid massage #facial immersion in cold water
Patient with (true) SVT given adenosine - possible outcomes?
Termination - suggests AV nodal rhythm
APCs increase risk for?
Treatment if symptomatic?
Afib
beta-blockers or CCBs
Atrial tachycardia - first line treatment? Second line?
β-blocker or nondihydropyridine calcium channel blocker (diltiazem or verapamil)
Most common type of SVT?
AVNRT
Typical AVNRT - pathway? General ECG findings? Specific ECG finding?
electrical conduction goes down the slow pathway and conducts back up toward the atrium over the fast pathway (slow-fast).
Short RP interval with a retrograde P wave inscribed very close to the QRS complex.
QRS complexes may appear as a pseudo R′ wave in lead V1 and a pseudo S wave in the inferior leads.
Atypical AVNRT - pathways? General ECG findings?
Conduction goes down the fast pathway and returns to the atrium via the slow pathway (fast-slow); this leads to a long RP interval.
Rarely, AVNRT can involve conduction over more than one slow pathway (slow-slow AVNRT).
Treatment to prevent recurrent AVNRT?
β-blockers or nondihydropyridine CCBs
AVRT - ECG findings?
Orthodromic vs antidromic?
shortened PR interval +/- slurred QRS (delta wave)
Anterograde conduction over AV node/His-purkinje system vs accessory pathway
Clinical importance in treatment of orthodromic vs antidromic AVRT?
Adenosine vs NO adenosine (can cause VF)
WPW is often seen in patients with this anomaly?
Ebstein anomaly (right heart enlargement and severe tricuspid valve regurgitation)
Non-invasive risk stratification for patients with preexcitation? Low risk if what findings?
exercise stress testing. Loss of preexcitation with exercise
First line therapy for patients with preexcitation with symptoms?
catheter ablation
