February 2, 2016 - Bradyarrhythmias Flashcards Preview

COURSE 3 > February 2, 2016 - Bradyarrhythmias > Flashcards

Flashcards in February 2, 2016 - Bradyarrhythmias Deck (16):

Causes of Bradycardia

1. Insufficient impulse formation... such as sinus node dysfunction

2. Insufficient impulse conduction... such as AV block


Sinus Node Dysfunction (SND)

Inappropriately slow sinus rate

ECG and clinical judgement are required for this diagnosis


Sick Sinus Syndrome (SSS)

Symptoms due to sinus node dysfunction (SND).

For example, an asymptomatic 70 year old with resting sinus bradycardia of 50 bpm likely has sinus node dysfunction, BUT, doesn't have SSS until symptoms develop.


Sinus Pause

A gap of more than 3 seconds between QRS complexes.

Commonly seen in normal people when sleeping, but is abnormal when awake.


Gold Standard for Diagnosing SSS

Symptom-rhythm correlation.

Record inappropriately low sinus rate during symptoms.


Holter Monitor

Can be used to continuously monitor a patient for 24-48 hours.


Chronotropic Incompetence

Heart rate does not respond appropriately to exercise.

Failure to achieve 80% of age predicted heartrate.

Age predicted heartrate = 220 - age


Symptoms of Sinus Node Dysfunction

The most common is syncope.

Can also present as falls in the elderly, effort intolerance, or chronic fatigue.


Tachy-Brady Syndrome

Is a variant of Sick Sinus Syndrome (SSS) in which slow arrhythmias and fast arrhythmias alternate.

50% of patients with SSS will develop this.


Cause of SND

Most common cause is aging and fibrosis of the sinus node.


Treatment of SND

Reverse the correctable causes.

If this cannot be done, consider using a permanent pacemaker.


First Degree AV Block

AV delay

PR interval is longer than 200ms

Every p-wave is conducted

Blockage is in either the AV node or the His-Purkinje fibers


Third Degree AV Block

Atria and ventricles are not communicating.

Hopefully an escape rhythm in the ventricles.

Blockage is either in the AV node or the His-Purkinje fibers.

Can see cannon A waves because when the atrium contracts and the valve to the ventricles does not open, all the blood shoots back into the venous system.

Indications for a pacemaker.


Second Degree AV Block - Type I

Mobitz I

Usually a block in the AV node.

The PR interval gradually lengthens before a P-wave block, and the cycle begins again.


Second Degree AV Block - Type II

Mobitz II

The PR interval remains constant before a P-wave blocks, and the cycle begins again.

Usually a conduction block in the His-Purkinje fibers.

This is worse than Type I. Indications for a pacemaker.


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