Cardiac Arrhythmia- Bradycardia

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1. Heart Block Definition

First Degree - PR interval > 0.2 seconds

Second Degree - Intermittent AV conduction

Third Degree - Atrial impulses do not conduct

2. Bradycardia

Heart Rate < 60 beats/min.

·Asymptomatic

Athletic conditioning

Sinus bradycardia

·Symptomatic

Inadequate cardiac blood flow

Loss of atrial augmentation

Dizziness, syncope (inadequate cerebral blood flow)

3. Heart Block - Complete

·Causes

Congenital- often asymptomatic

Valvular calcification- Aortic, Mitral

Myocardial infarction- inferior, anterior septal

Surgical- VSD repair, subvalvular stenosis resection, valve replacement (IHSS)

4. Sinus Node Dysfunction

Amyloid deposition

·Surgical damage

Fontan repair, atrial switch, Maze II, superior approach for Mitral valve repair

·Sick sinus syndrome

Tachycardia, bradycardia

Diagnosis by prolonged ambulatory ECG

5. Carotid Sinus Syndrome

·Cardio-inhibitory- Carotid sinus stimulation

3 second or greater pauses

pacemaker appropriate

·Vasodepressor- Carotid sinus depression with Atropine

BP drops without slowing

pacemaker may not help symptoms

6. Indications

·Symptomatic bradycardia

Syncope, dizziness, exercise intolerance, CHF

·Asymptomatic bradycardia

profound bradycardia, usually brief

congenital third degree heart block with wide QRS complex

BBB?? with intermittent second degree heart block post-MI

bifasicular block with intermittent second degree heart block

IHSS

CARDIAC PACING NBG Code

I	II	III	IV
Chamber Paced	Chamber Sensed	Response to Sensing	Programmable Function
V- Ventricle	V- Ventricle	T- Trigger pacing	P- Simple programmable
A- Artium	A- Atrium	I- Inhibits pacing	M- Multi-programmable
D- Dual (A&V)	D- Dual (A&V)	D- Dual (T&I)	C- Telemetry
O- None	O- None	O- None	R- Rate responsive
			O- None

7. Lead placing

·Atrial

Threshold

Pacing

Sensing >/= 2 mVolt

·Ventricular

Threshold

Pacing

Sensing >/= 5 mVolts

Slow rate >/= 0.8 mVolts/sec.