Cardiology

Question 1

Sinus node dysfunction: causes of bradycardia

Answer 1

Fibrodegenerative
Prior surgery
Collagen vascular disease
Infiltration disease

Question 2

Causes of bradycardia: vagal mediated and other

Answer 2

Athletic heart
Infection
CNS (increased ICP)

Question 3

Causes of bradycardia: Metabolic/endocrine

Answer 3

Hyperkalemia
Hypermagnrsemia
Hypothyroidism
Hypothermia
Hypoglycemia
Hypoxia

Question 4

Tachy-Brady syndrome

Answer 4

Alternating episodes of SVT with prolonged sinus pauses after conversion to sinus rhythm due to sinus node dysfunction

Place pacemaker

Question 5

Atropine

Answer 5

To treat bradycardia

0.5 mg in q3-5min for max of 3 mg

Use cautiously in acute MI as increased heart rate can worsen ischemia or zone of infarction

Use cautiously in heart transplant as it may be ineffective or you can get a paradoxical response

Question 6

Bradycardia medical treatment

Answer 6

Atropine
Epinephrine
Dopamine
Isoproterenol
Glucagon: to be used in bradycardia due to beta blockers It CCB overdose

Question 7

Persistent bradycardia

Answer 7

-atropine can be ineffective for second degree type 2 AV block or complete heart block either new BBB
-dopamine and epi can be useful for Brady associated with hypotension
-dopamine has beta adrenergic activity at 5-10 and alpha at >10

Question 8

Atrial tachycardia

Answer 8

Can look like AV block but is different. Look at atrial rate. The AV node is healthy

Question 9

Classification of AV block

Answer 9

First degree: prolonged PR interval
Second degree type 1: progressive elongation of PR and then dropped QRS
Second degree type 2: fixed PR with dropped QRS
Third degree: complete heart block

Question 10

AV block and tx

Answer 10

Place pacemaker if infra-nodal conduction: second degree type 2 and third degree

Question 11

Bradyarrhythmia after acute MI

Answer 11

Sinus Brady: in 50% of pts
Due to disruption of blood flow in SA node artery
Due to increased vagal tone in first 6 hours after inferior wall MI

Question 12

AV Block after MI

Answer 12

First degree: <15%
Second degree: 10%, type 2 a/w anterior wall infarction
Third degree: 5-10%: transient with inferior wall infarction due to vagal tone

Question 13

Tx of post MI Brady

Answer 13

Treat if symptomatic, sinus pause >3 sec, HR <40 and hypotensive

Atropine
Pacing

Question 14

Indications for TV Temp pacing

Answer 14

-asystole
-alternating right and left BBB
-second degree type 2 AV block with new BBB
-second degree type 2 block with fascicular block (right or left axis deviation) and RBBB
-third degree av block

Question 15

Common pacing modes

Answer 15

AAI: used for sinus node dysfunction with intact AV conduction. Maintains AV synchrony

VVI: used when AV conduction is not intact. Useful for backup pacing for actual arrhythmias. Does not maintain AV synchrony

DDD: used for all degrees of AV block and maintains AV synchrony

Question 16

AV Synchrony

Answer 16

Accounts for 25% of cardiac output

Question 17

Magnet Mode

Answer 17

Useful to stop pacemaker mediated tachycardia or to prevent inappropriate pacing inhibition from electrical noise (bovie knife)

Magnet over an ICD inhibits shocks but doesn’t affect pacing mode

Question 18

Causes of inappropriate ICD firing

Answer 18

Electromagnetic interference on sensing lead
Lead malfunction (fracture)
SVT with rapid ventricular conduction
Placing magnet over ICD