4,199
edits
Intraventricular Conduction: Difference between revisions
Jump to navigation
Jump to search
m
→Left Posterior Fasicular Block (LPFB)
| (10 intermediate revisions by 3 users not shown) | |||
| Line 4: | Line 4: | ||
|Supervisor= | |Supervisor= | ||
}} | }} | ||
=Conduction delay= | |||
[[Image:geleidingssysteem.jpg|thumb| If the conduction system is dysfunctional, the QRS widens beyond 0.12 seconds.]] | [[Image:geleidingssysteem.jpg|thumb| If the conduction system is dysfunctional, the QRS widens beyond 0.12 seconds.]] | ||
If the QRS complex is wider than 0.12 seconds this is mostly caused by a delay in the conduction tissue of one of the bundle branches: | If the QRS complex is wider than 0.12 seconds this is mostly caused by a delay in the conduction tissue of one of the bundle branches: | ||
| Line 14: | Line 14: | ||
*[[#Left_Posterior_Fasicular_Block_.28LPFB.29| Left posterior fascicular block (LPFB)]] | *[[#Left_Posterior_Fasicular_Block_.28LPFB.29| Left posterior fascicular block (LPFB)]] | ||
Sometimes this conduction delay is ''' | Sometimes this conduction delay is '''rate-dependent ''': the bundle branch block occurs only at higher heart rates and disappears at slower heart rates. | ||
{{clr}} | {{clr}} | ||
= LBBB vs RBBB = | |||
[[Image:LBTB_RBTB_en.png|thumb| A bundle branch block causes a delay in the depolarization of the right (RBBB) or left (LBBB) ventricle. In RBBB the QRS complex shows a second peak or R' in V1.]] | [[Image:LBTB_RBTB_en.png|thumb| A bundle branch block causes a delay in the depolarization of the right (RBBB) or left (LBBB) ventricle. In RBBB the QRS complex shows a second peak or R' in V1.]] | ||
Check V1 when QRS > 0.12 sec. | Check V1 when QRS > 0.12 sec. | ||
| Line 25: | Line 25: | ||
{{clr}} | {{clr}} | ||
=Left Bundle Branch Block (LBBB)= | |||
{{:LBBB}} | {{:LBBB}} | ||
{{clr}} | {{clr}} | ||
=Right Bundle Branch Block (RBBB)= | |||
{{:RBBB}} | {{:RBBB}} | ||
=Left Anterior Fascicular Block (LAFB)= | |||
{{Box| | {{Box| | ||
;Criteria for | ;Criteria for Left Anterior Fascicular Block | ||
#Frontal plane axis between −45° and −90°. | |||
#qR pattern in lead aVL. | |||
#R-peak time in lead aVL of 45 ms or more. | |||
#QRS duration less than 120 ms. | |||
These criteria do not apply to patients with congenital heart disease in whom left-axis deviation is present in infancy. | |||
}} | }} | ||
[[Image:LAHB.png|thumb|Left anterior hemiblock]] | [[Image:LAHB.png|thumb|Left anterior hemiblock]] | ||
| Line 46: | Line 46: | ||
{{clr}} | {{clr}} | ||
=Left Posterior Fasicular Block (LPFB)= | |||
[[File:E0003194.png|thumb|A patient with [[RBBB]] and left posterior Fascicular block]] | |||
{{Box| | {{Box| | ||
;Criteria for posterior fascicular block: | ;Criteria for posterior fascicular block: | ||
#Frontal plane axis between 90° and 180° in adults. Owing to the more rightward axis in children up to 16 years of age, this criterion should only be applied to them when a distinct rightward change in axis is documented. | |||
#rS pattern in leads I and aVL. | |||
#qR pattern in leads III and aVF. | |||
#QRS duration less than 120 ms. | |||
:Right ventricular [[hypertrophy]] and previous [[Ischemia#Lateral|lateral myocardial infarction]] have been excluded | :Right ventricular [[hypertrophy]] and previous [[Ischemia#Lateral|lateral myocardial infarction]] have been excluded | ||
}} | }} | ||
=Mechanisms of aberrant conduction= | |||
[[Image:E000573.jpg|Rate dependant left bundle branch aberration|thumb]] | |||
{{box| | {{box| | ||
;Aberrant ventricular conduction is defined as | ;Aberrant ventricular conduction is defined as | ||
| Line 79: | Line 82: | ||
This is the most common mechanism for sustained aberrancy during tachycardia. The sequence of QRS widening that is often observed is phase 3 aberration in the first premature beat. This can leave the left bundle (for example) refractory for the next complex. This next beat is conducted by the right bundle and once it reaches the apex, it is conducted retrograde by the left bundle. This can continue until a new premature ventricular complex causes a compensatory pause and 'resets' the system. | This is the most common mechanism for sustained aberrancy during tachycardia. The sequence of QRS widening that is often observed is phase 3 aberration in the first premature beat. This can leave the left bundle (for example) refractory for the next complex. This next beat is conducted by the right bundle and once it reaches the apex, it is conducted retrograde by the left bundle. This can continue until a new premature ventricular complex causes a compensatory pause and 'resets' the system. | ||
===Fixed Bundle Branch Block=== | ===Fixed Bundle Branch Block=== | ||
[[File:Fixed_LBBB.svg|thumb|LBBB due to fixed bundle branch block | [[File:Fixed_LBBB.svg|thumb|LBBB due to fixed bundle branch block]] | ||
Complete or marked conduction delay in a bundle branch leading to complete ventricular activation over the contralateral bundle branch. | Complete or marked conduction delay in a bundle branch leading to complete ventricular activation over the contralateral bundle branch. | ||
{{clr}} | {{clr}} | ||
{{Box| | {{Box| | ||
=References= | |||
<biblio> | <biblio> | ||
#Garcia isbn=0763722464 | #Garcia isbn=0763722464 | ||