Bradycardia

Question 1

What are some modulators of heartrate?

Answer 1

age, gender, physical training, activity of pharmacologic agents

Question 2

intrinsic causes of sinus node dysfunction

Answer 2

disorder of impulse formation

failure of conduction

causes: age associated fibrosis, coronary atherosclerosis, fibrosis due to hypertension and diabetes, cardiovascular disease, familial disease, pericardial disease, amyloidosis

Question 3

extrinsic causes of sinus node dysfunction

Answer 3

increased vagal tone

medications

electrolyte abnormalities

severe hypotension or hypoxemia

Question 4

pharmacologic agents that can suppress sinus node function

Answer 4

beta-blockers, calcium blockers, digoxin, antiarrhythmic drugs, and psychotropic medications

Question 5

treatment of external dysfunction

Answer 5

removing offending stimulus

Question 6

treatment of internal dysfunction

Answer 6

pacemaker implantation

Question 7

estimation of maximum sinus rate

Answer 7

220 - age

Question 8

sinus bradycardia ECG

Answer 8

normap p-wave axis with heart rate of <60 bpm

every P wave is followed by a QRS complex

Question 9

sinus arrest

Answer 9

normal P-wave axis

every P-wave followed by a QRS complex

pauses of >3 seconds without atrial activity

Question 10

SA exit block

Answer 10

normal P-wave axis

progressive shortening of PP interval until one P wave fails to conduct or sinus pause is an exact multiple of the baseline PP interval

Question 11

bradycardia-tachycardia syndrome

Answer 11

alternating periods of atrial tachycardia and bradycardia

Question 12

types of AV block

Answer 12

first-degree

second degree - mobitz I and II

2:1 AV block

high-grade

complete heart block

Question 13

symptoms of bradyarrhythmia

Answer 13

syncope

presyncope/dizziness

poor exercise tolerance/fatigue

congestive heart failure

can also have no symptoms

Question 14

What is the depolarization rate of the AV node?

Answer 14

40-60 bpm

Question 15

What is the depolarization rate of the ventricles?

Answer 15

20-40 bpm

Question 16

first-degree AV block

Answer 16

delay, no dropped beats

Question 17

second degree AV block - Mobitz Type I (Wenckebach)

Answer 17

progressive delay with dropped beats

Question 18

2nd degree AV block - Mobitz Type II

Answer 18

fixed delay with dropped beats

block is in the His-Purkinje system, which is more severe than the Type I block

Question 19

3rd degree AV block

Answer 19

complete AV block, no conduction from atria to ventricles

Question 20

right bundle branch block

Answer 20

left bundle and left ventricle depolarize normally and rapidly

right ventricle depolarizes slowly via cell-to-cell mechanism

leads to a wide QRS complex and rabbit ears phenomenon

Question 21

left bundle branch block

Answer 21

right bundle and right ventricle depolarize normally and rapidly

left ventricle depolarizes slowly via a cell-to-cell mechanism

wide QRS, low and lobbing in lead V1