bundle branch blocks and abberation

Question 1

what are bundle branch blocks caused by?

Answer 1

lesions or pathologic conditions in the HIS bundle fibres as they join into the bundle branches or more commonly, in the bundle branches themselves.

myocardial ischemia, infarctions or fibrosis. can occur in either branch

Question 2

what are the bundle branches also referred to as ? how many branches on each side?

Answer 2

fascicles.right has a single fascicle and left has 2, referred to as the anterior and posterior fascile

Question 3

are bundle branch blocks temporary or perm?

Answer 3

permanent intraventricular (within the vesicles) conduction problem or delays

Question 4

what gives us clues regarding which bundle branch is blocked?

Answer 4

certain leads.

Question 5

how would the QRS look if there is a BBB

Answer 5

wide QRS cause impulse is delayed.

Question 6

do BBB occur in any rhythm?

Answer 6

any supra ventricular rhythm such as SR or afib so SR with BBB. so normal p wave an wide QRS

Question 7

how would afib with BBB look

Answer 7

usual clues with afib (fib line w irregular R-R intervals) and wide QRS

Question 8

what is the 3 fascicle intraventricular conduction system also called?

Answer 8

trifasciular

Question 9

where is the left (superior division) and right bundle branch located?

what does this mean for MIs

Answer 9

both anterior structures so vulnerable to anteroseptal MI

Question 10

the posterior division of the LBB is supplied by what coronary artery?

Answer 10

right

Question 11

what are some ECG clues for BBB

Answer 11

QRS .12 or greater and wide QRS can also occur w any supra ventricular rhythm

t wave opposite to terminal wave of fQRS

perm

right BB QRS morphology in V1 rSr and V6 qRs

left BB QRS morph . V1 mainly neg complex QS or rS
V6 always positive

Question 12

causes of BBB?

Answer 12

myocardial ischemia/infarct

drugg iduced

fibrosis

RBBB usually associated with anterior MI (left anterior descending- LAD vessel feeds the r. bundle)

LBBB associated with inferior or anterior MI (right coronary artery feeds thicker posterior fascicle of left bundle)

LAD coronary artery feeds thiner anterior fascicle of left bundle

Question 13

what are the hemodynamic effects of BBB

Answer 13

dep on underlying rate or rhythm

if rate inc e.g. sinus tach - less time for filling so dec SV, CO, BP

if afib then loss of atrial kick so dec SV, BP, and CO

if rate slow same as above

Question 14

treatment for BBB

Answer 14

pacemaker if signs of intermittent or perm conduction failure

if no conduction failure then treatment is aimed at underlying rhythm as nec

Question 15

what is aberration?

Answer 15

term used to describe a supra ventricular beat that finds one of the bundle branches not ready to conduct.

abberant means ‘straying away from the right way or wandering’

Question 16

what do aberrant beats produce?

Answer 16

changing QRS complexes which are wide and appear in ventricular in origin

Question 17

what is a non-conducted PAC?

Answer 17

abberation betts are commonly premature supraventricular impulses (usually PACs) that have deviated from normal ventricular conduction. normally when a PAC reaches the ventricles, it is uniformly conduced down he BB and there is a normal QRS but if the PAC is very premature, bundle branches may be refractory (not ready to conduct) and PAC will not be conduced at all and no QRS is produced

Question 18

what happens if the PAC finds the BB partially refractory? what is this called?

Answer 18

impulse may be conduced with delay, deviation or both.

abberant conduction

Question 19

what BB has the longest refractory period? what does this mean for conduction? what is it called

Answer 19

right BB so aberrantly conducted PAC usually find the right BB refractory or unable to conduct so impulse travels down the LBB and then back up the right (now no longer refractory)

called right bundle branch block pattern (RBBB) bc makes fun pattern

Question 20

is aberration pathological?

Answer 20

no usually temporary or transient and often rate related

Question 21

is there usually a p wave before the beat or no? what does this mean for PJCs?

Answer 21

yes usually before the aberrant beat although the PJCs can be conducted aberrantly as well

Question 22

are QRS complexes wide in BBB and aberration beats?

Answer 22

yes because intraventriclar conduction is delayed

Question 23

are both ventricles conducted at the same time in aberration and BBB?

Answer 23

no at different times which is not normal so depolarization is also abnormal . so t wave will be opposite QRS

Question 24

what lead gives you the best picture with wide QRS patients?

Answer 24

MCL1 or V1. allows you to differentiate between BBB, aberration and PVCs

Question 25

ECG clues with aberration?

Answer 25

wide WRS between .12-.14 usually

premature atrial contractions

sudden onset of SVT afib

can be rate related

t wave opposite to terminal wave of QRS

tends to be transient or temp

RBBB and LBBB same as previous

Question 26

possible causes of aberration?

Answer 26

sudden or premature stimulation of bundle branches while one bundle is still depolarizing (phase 3)

long pause in conduction (slow rate) where the beat finds the bundle already depolarized

retrograde concealed conduction (common cause in afib) integrate or normal conduct is blocked for example in left bundle so next beat goes back up left bundle once it is ready (retrograde)

Question 27

hemodynamic effects of aberration?

Answer 27

dep or underlying supraventrcular rythym

if rate inc or atrial kick lost then dec SV, CO, BP

Question 28

tx for aberration?

Answer 28

12 lead

treat underlying rhythm with med