Arrhythmias

Front 1

what is automaticity

Back 1

cell's ability to depolarize itself to a threshold voltage and generate a spontaneous action potential

Front 2

what are pacemaker cells

Back 2

specialized cardiac cells that are capable of automaticity and generate the electircal impulse in the heart. The leader is the cells capable of fastest depolarization (usually SA node)

Front 3

what is the heart's native pacemaker

Back 3

SA node

Front 4

what are some causes of conduction block

Back 4

ischemia, fibrosis, drugs (e.g. Beta blockers suppressing AV node)

Front 5

characteristics of sinus bradycardia

Back 5

decreased firing of SA node causes rate <60bpm. Sinus rhythm remains normal (P before every QRS). Not always pathological.

Front 6

causes of sinus bradycardia

Back 6

1. aging (SA node cells die)
2. Beta blockers (suppress SA node activity)
3. hypothyroidism (suppress SA node activity)
4. trained athletes (high vagal tone)

Front 7

in what pt population is sick sinus syndrome frequently seen

Back 7

elderly pts

Front 8

what is the cause of sick sinus syndrome

Back 8

an overdrive suppression of the SA node during tachyarrythymia, causes a period of profound sinus bradycardia

Front 9

what is the treatment for sick sinus syndrome

Back 9

anti-arrythmic drugs plus a permanent pacemaker

Front 10

characteristic ECG findings in junctional escape rhythms

Back 10

no P waves, slow rate (bradycardia), narrow QRS note: AV is pacemaker

Front 11

characteristic ECG findings in ventricular escape rhythms

Back 11

no P waves, slow rate (bradycardia), wide QRS with RR'. note: SA and AV shut down and His/purkenje are pacemakers

Front 12

characteristic ECG finding in 1st degree AV block

Back 12

long PR interval (>200msec or >1 big box), normal rhythm

Front 13

causes of 1st degree AV block

Back 13

reversible: increased vagal tone, beta blockers
irreversible: MI, aging

Front 14

sx of 1st degree AV block

Back 14

usually asymptomatic and benign

Front 15

characteristic ECG findings in Mobitz type I 2nd degree AV block (Wenkebach)

Back 15

progressively longer PR interval and then a dropped beat (no QRS)

Front 16

Wenkeback AV block (2nd degree Mobitz type I) is usually seen in which pt populations

Back 16

kids, trained athletes, during sleep. Usually benign

Front 17

treatment for Wenkeback AV block (2nd degree Mobitz type I)

Back 17

typically not necessary

Front 18

Wenkeback AV block (2nd degree Mobitz type I) pathophysiology

Back 18

impaired conduction of AV node

Front 19

2nd degree AV block Mobitz type II: ECG findings

Back 19

sudden intermittent loss of QRS, PR intevals before and after the dropped beat are the same length, normal rhythm

Front 20

2nd degree AV block Mobitz type II: cause

Back 20

usually caused by conduction block beyond AV node

Front 21

2nd degree AV block Mobitz type II: treatment

Back 21

pacemaker

Front 22

2nd degree AV block Mobitz type II: complications

Back 22

can progress to complete heart block

Front 23

3rd degree AV block: pathophysiology

Back 23

atria and ventricles completely dissociated, escape rhythm drives ventricles

Front 24

3rd degree AV block: ECG findings

Back 24

no relationship between P waves and QRS, T waves have abnl morphology because P wave can occur at same time and distort the T, wide QRS due to escape rhythm

Front 25

3rd degree AV block: treatment

Back 25

permanent pacemaker almost always needed

Front 26

3rd degree AV block: etiology

Back 26

acute MI or degeneration of conduction system with age

Front 27

sinus tachycardia: ECG findings

Back 27

nl sinus rhythm but rate > 100bpm

Front 28

sinus tachycardia: cause

Back 28

increased sympathetic or decreased vagal tone from a primary pathological cause (like infection)

Front 29

sinus tachycardia: txt

Back 29

treat the underlying cause

Front 30

ectopic atrial tachycardia: ECG findings

Back 30

looks like sinus tachycardia but abnl P waves (some positive, some negative. Should be + in I, avF)

Front 31

ectopic atrial tachycardia: cause

Back 31

increased automaticity from ectopic atrial site

Front 32

ectopic atrial tachycardia: txt

Back 32

beta blockers, calcium channel blockers, anti-arrythmics

Front 33

atrial flutter: ECG findings

Back 33

rapid regular atrial activity at a rate of 180-350bpm, saw tooth appearance, regular rhythm, regular extra Ps (atrial to vent depol can be 2:1 or 3:1)

Front 34

atrial flutter: cause

Back 34

reentry over a large anatomical fixed circuit

Front 35

atrial flutter: txt

Back 35

ablation or drugs (anti arrythmics, rate control agents)

Front 36

AV nodal reentry: ECG findings

Back 36

fast rate, P waves inside QRS

Front 37

AV nodal reentry: cause

Back 37

fast beta pathway in AV node refractory so slow alpha pathway depolarizes first and goes back up the beta side thereby producing simultaneous atrial and ventricular depolarization

Front 38

ECG characteristics of Wolff-Parkinson-White syndrome

Back 38

shortened PR interval, widened QRS, delta waves

Front 39

atrial fibrillation: ECG findings

Back 39

chaotic atrial rhythm (irregularly irregular) with no discernible P waves

Front 40

atrial fibrillation: txt

Back 40

rate control drugs (beta blockers, CCB), anti-arrythmics, anti-coag

Front 41

atrial fibrillation: complications

Back 41

thrombis because stagnate blood

Front 42

mutli focal atrial tachycardia: ECG findings

Back 42

irreg rhythm, >100bpm, multiple P wave morphologies

Front 43

mutli focal atrial tachycardia: cause

Back 43

abnl automaticity in several foci within atria (often occurs in setting of severe pulm ds because high RAP stretches condunction sys)

Front 44

mutli focal atrial tachycardia: txt

Back 44

verapamil

Front 45

ventricular tachycardia: ECG findings

Back 45

wide QRS that occur at rate of 100-200bpm (hard to see Ps and Ts)

Front 46

ventricular tachycardia: cause

Back 46

in pts with severe structural heart dz, have severe sx like syncope

Front 47

ventricular tachycardia: txt

Back 47

cadioversion or anti-arrythmic drugs

Front 48

torsades: ECG

Back 48

varying amplitude of QRS

Front 49

torsades: cause

Back 49

electrolyte disturbance (hypokalemia, hypomagnesium), severe bradycardia, anti-arrhythmic drugs

Front 50

torsades: txt

Back 50

IV magnesium

Front 51

ventricular fibrillation: ECG

Back 51

disordered rapid stimulation of ventricles with no coordinated contractions

Front 52

ventricular fibrillation: cause

Back 52

can be from acute MI- major cause of death in these pts

Front 53

ventricular fibrillation: txt

Back 53

prompt electrical defib and ICD if they survive