ECG

Question 1

Sinus pause

Answer 1

normal sinus node fails to pace for at least one cycle

Question 2

AV block

Answer 2

Delay or block in the impulse as it spreads from the atria to ventricles resulting in a dropped QRS complex

Question 3

Potential causes of AV block

Answer 3

rate-slowing medications including calcium channel blockers, beta blockers, digoxin, and anti-arrhythmic medications.

Question 4

Four types of AV block

Answer 4

first degree, second degree type 1, second degree type 2, and third degree or complete heart block

Question 5

First degree AV block

Answer 5

DELAY in the spread of an impulse from the sinus node to the AV node

PR interval greater than 200 ms (0.2 sec) or one large square on EKG

Question 6

Second degree AV block - Mobitz Type I

Answer 6

progressive lengthening of PR interval from cycle to cycle prior to a dropped QRS complex

As the impulse becomes more and more delayed, the AV node eventually and temporarily becomes more and more delayed, the AV node eventually is no longer able to carry the electrical message from the SA node.

PR interval gradually lengthens and the QRS is normal

Question 7

Symptoms and treatment of mobitz type I

Answer 7

Asymptomatic unless there is a very slow ventricular response or if the dropped QRS is associated with a long pause.

Tx: reversible if associated with rate-slowing medication. In asymptomatic individuals, there is no specific treatment.

Question 8

Second degree AV block - Mobitz type II

Answer 8

more serious but less common type of heart block associated with a punctual P wave followed by intermittently dropped QRS complexes.

The PR interval is fixed and the QRS duration is wider than normal.

Question 9

Anatomic location of mobitz type I and type II

Answer 9

Type 1: AV node

Type II: infra-hisian, originating distal to the AV node

Question 10

Treatment of mobitz type II

Answer 10

irreversible and pacemaker is usually recommended

Question 11

blocked premature atrial contraction (PAC)

Answer 11

similar to mobitz type II resulting in a premature P wave that is not followed by a QRS. When the next P wave comes through, it results in a resetting of the overall atrial cycle length.

Question 12

2:1 AV block

Answer 12

every other QRS is dropped

Question 13

third degree AV block

Answer 13

complete heart block

Question 14

third degree AV block

Answer 14

more p waves than QRS complexes, no consistent PR interval, AV dissociation, and ventricular rate is often 20-30 bpm

Question 15

Complication of complete heart block

Answer 15

myocardial infarction, at risk for death from asystole, and bodily injury from syncope

Question 16

Right and Left bundle branch block

Answer 16

QRS duration greater than 120 ms

Question 17

Right bundle branch block (RBBB)

Answer 17

“classic bunny ear” appearance - left ventricle contracts before the right ventricle, resulting in two joined but out of sync QRS complexes on the EKG

Causes an RR’ pattern

Question 18

causes of RBBB

Answer 18

Normally: occurs as a result of normal aging in patients with fibrocalcific conduction disease

Abnormally: occurs in any condition that may affect the right side of the heart (atrial septal defect, right ventricular hypertrophy, pulmonary stenosis, pulmonary arterial hypertension, or pulmonary embolus)

Question 19

Left bundle branch block (LBBB)

Answer 19

widened QRS complex (just like rbbb) but with an inverted T wave due to the change in repolarization that occurs

Question 20

causes of LBBB

Answer 20

associated with structural heart disease. LBBB is commonly associated with coronary artery disease or valvular heart disease but it also occurs as a result of fibrocalcific changes