Cardiac rhythm monitors & equipment 4 Flashcards
A patient with Wolff-Parkinson-White syndrome develops atrial fibrillation during surgery. Select the BEST treatment for this situation. (select 2)
a. cardioversion
b. verapamil
c. digoxin
d. procainamide
a. cardioversion
d. procainamide
Wolff-Parkinson White is the most common
pre-excitation syndrome
The defining feature of WPW consists of
an accessory conduction pathway (Kent’s bundle) that bypasses the AV node & the conduction delay associated with it
A key diagnostic feature of WPW on the EKG is
a delta wave
The most common tachydysrhythmia associated with WPW is
AV nodal reentry tachycardia
AV nodal reentry tachycardia can be classified as
orthodromic or antidromic
The most common AV nodal reentry tachycardia is
orthodromic
Orthodromic AV nodal reentry tachycardia is associated with
a narrow QRS complex
Treatment for orthodromic AV nodal reentry tachycardia includes
increasing the refractory period at the AV node (vagal maneuvers, amiodarone, adenosine, beta-blockers, verapamil, or cardioversion)
Antidromic AV nodal reentry tachycardia is associated with
a wide QRS complex
Treatment for antidromic AVNRT includes
increasing the refractory period of the accessory pathway (procainamide or cardioversion)
With antidromic AVNRT, these agents should be avoided:
agents that increase the refractory period of the AV node
Common characteristics observed on the EKG of a WPW include:
delta wave caused by ventricular preexcitation
short PR interval (<0.12 seconds)
wide QRS complex
possible T wave inversion
Drugs to avoid with antidromic AVNRT include
adenosine
digoxin
calcium channel blockers
beta-blockers
lidocaine
The combination of AF & WPW can precipitate
CHF, ventricular fibrillation, & death
Definitive treatment for WPW is
ablation of the accessory pathway
A complication of radiofrequency ablation of the left atrium is
thermal injury to the left atrium and esophagus
monitor esophageal temperature & let cardiologist know if it rises
Is orthodromic AVRNT or antidromic AVRNT more dangerous in the patient with atrial fibrillation? Why?
antidromic AVRNT- the AV node is bypassed and the ventricular rate can increase dramatically (up to 300 bpm) causing CHF and ventricular fibrillation
All of the following increase the likelihood of torsades de pointes in the patient with long QT syndrome EXCEPT:
a. hyperventilation
b. furosemide
c. methadone
d. metoprolol
d. metoprolol
Torsades de pointes is a
polymorphic ventricular tachycardia
Torsades de pointes is typically
self-limiting but it can deteriorate into ventricular fibrillation
Torsades de pointes is usually associated with a
prolonged QT interval
Conditions that prolong the QT interval include
hypokalemia
hypomagnesemia
methadone
droperidol
ondansetron
amiodarone
hypertrophic cardiomyopathy
bradycardia
Acute treatment for torsades de points includes
magnesium sulfate & cardiac pacing
What genetic syndrome can prolong QTc?
Romano-Ward Syndrome
Timothy syndrome
The mnemonic for QTc prolongation is
POINTES
POINTES stands for
phenothiazines
other meds
intracranial bleed
no known cause
type 1 antiarrhythmic drugs
electrolyte disturbances
syndromes
A prolonged QT interval is defined as
> 0.45 seconds in men
0.47 seconds in women
Prevention of torsades de points in patients with a long QT interval includes
patients with long QT syndrome may require beta-blocker prophylaxis and/or IC placement
avoid SNS stimulation
All drugs that prolong the QTc interval include
methadone
droperidol
haloperidol
ondansetron
halogenated agents
amiodarone
quinidine
What type of electrical stimulus can initiate torsades de pointes?
A PVC or poorly timed pacer discharge during the second half of the T wave (R on T phenomenon)
Name 3 electrolyte disturbances that can prolong the QTc.
hypomagnesemia
hypokalemia
hypocalcemia
A pacemaker consists of a
pulse generator & pacing leads that deliver electrical current to the heart
Pacemakers are characterized by a
5 letter code
Position 1 indicates
chamber paced
Position 2 indicates
chamber sensed
Position 3 indicates
response to sensed native cardiac activity
Position 4 indicates
programability options
Position 5 indicates
the pacemaker can pace multiple sites
Common pacing modes include
asynchronous pacing
single-chamber pacing
dual-chamber pacing
Failure to capture occurs when the
pacemaker delivers an electrical stimulus but fails to trigger myocardial depolarization
Indications for pacemaker insertion include
symptomatic diseases of impulse formation
symptomatic disease of impulse conduction
long QT syndrome
dilated cardiomyopathy
hypertrophic obstructive cardiomyopathy
The pneumonic for pacemakers is
PaSeR
chamber Paced
Chamber Sensed
Response
O in the positions stands for
none
Position 3 can have the following letters:
O= none
T= triggered
I= inhibited
D= dual (triggered & inhibited)
Position 4 can have the following letters:
o= none
R= rate modulation
Single-chamber demand pacing can be thought of as
a backup mode- it only fires when the native heart rate falls below a predetermine rate
Asynchronous pacing delivers
a constant rate
The most common mode of pacing is
dual-chamber AV sequential demand pacing - improves AV synchrony
A patient undergoing a bunionectomy has a VOO pacemaker with a rate of 80 bpm. During the procedure, there is a failure to capture and the heart rate decreases to 50 beats per minute. Which of the following BEST explains why this complication occurred?
a. the EtCo2 was 20 mmHg
b. an ultrasonic harmonic scalpel was used
c. the patient was hyperthermic
d. the electrocautery setting was changed from “coagulation” to “cutting”
a. the EtCo2 was 20 mmHg
