12 Lead ECG Interpretation – Part 2

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This is the second installment into the 12 Lead ECG Interpretation Series for my Paramedic Students.

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12 Lead ECG Interpretation – Part 2:

12 Lead ECG Interpretation – Part 2 Understanding Bundle Branch Blocks P. Johnson; BA, NREMT-P, WV-MCCP

Review notes from today’s in-class lecture :

authorstream.com pjohnson_ALSEDU Review notes from today’s in-class lecture Course Textbooks: Bob Page’s 12 Lead ECG Interpretation, & Barbara Aehlert’s Paramedic Practice Today

Objectives::

Objectives: Understanding bundle branch blocks Describe differentiation of right and left bundle branch block using lead V 1 Describe the clinical significance of bundle branch blocks Understand diagnostic problems associated with LBBB

Conduction Pathway Review::

Conduction Pathway Review:

Conduction Pathway Review::

Conduction Pathway Review: Atrial Conduction SA node AV node Bundle of His Typically THE connection between the atria and ventricles Connects the bundle branches Bundle Branches Conduct electricity to the Purkinje fibers on the right and left ventricle

Conduction of Electricity to the Right Ventricle:

Conduction of Electricity to the Right Ventricle Travels through the interventricular septum Only one fascicle to contract the entire right ventricle

Conduction of Electricity to the Left Ventricle :

Conduction of Electricity to the Left Ventricle Travels through the interventricular septum Overcomes greater pressures to contract & push blood out of the aorta Divides into two fascicles Anterior Fed by the LAD Posterior Fed by the RCA and Circumflex

Conduction Pathway Review:

Conduction Pathway Review Under normal conditions: Left and Right ventricle will depolarize simultaneously If a blockage occurs in a bundle branch… The ventricles will depolarize at separate intervals

Finding That Bundle Branch Block!:

Finding That Bundle Branch Block!

BBB Criteria::

BBB Criteria: QRS duration Greater than 0.12 Greater than 120 millisec . REMINDER: 12 Lead ECG Machine CAN measure the Intervals Accurately

Diagnosing Bundle Branch Blocks:

Diagnosing Bundle Branch Blocks V1 is the lead to use to call a bundle branch block. Go to lead V1 Find the J point Draw a line back toward the complex Shade up or down in the direction of the deflection

Turn Signals:

Turn Signals Shade up: Right Bundle Branch Block Shade down: Left Bundle Branch Block

Bob Page Charting:

Bob Page Charting

What’s the Big Deal Anyway?!?!?:

What’s the Big Deal Anyway?!?!?

Significance of a BBB:

Can be permanent or temporary In the setting of an AMI, BBB indicates extensive coronary artery occlusion and wall damage. The problem with a Left BBB LBBB obscures ST segments making ECG diagnosis of an AMI difficult. Many cardiologists don’t even try to diagnose an AMI in this case! Significance of a BBB

Significance of a BBB:

RBBB coupled with a hemiblock is referred to as a bifascicular block (two of three fascicles are blocked) LBBB is also a bifascicular block If a bifascicular block exists: Drugs such as lidocaine , procainamide , amiodarone , and morphine can further slow conduction causing complete heart blocks, and asystole ! Significance of a BBB

Hemodynamic effects of BBB:

BBB cause the ventricles to fire out of sync, which can: decrease preload. delay conduction and depolarization time . QRS complex greater than 170ms (0.17 sec) with a BBB have an ejection fraction less than 50% NOTE: Normal ejection fraction 60-75%. Vasodilation meds… ie : NTG can cause drop in BP of these patients....which ultimately causes the patient to loose their compensatory abilities! Hemodynamic effects of BBB

Time to Practice!:

Reviewing interpretation of Bundle Branch Blocks Time to Practice!

Left Bundle Branch Block:

Left Bundle Branch Block

Right Bundle Branch Block:

Right Bundle Branch Block

No Bundle Branch Block Present!:

No Bundle Branch Block Present!

Let’s Incorporating Axis/Hemiblock, and Bundle Branch Blocks:

Infusion of lectures: part 1 and part 2 Let’s Incorporating Axis/ Hemiblock , and Bundle Branch Blocks

authorstream.com:

authorstream.com pjohnson_ALSEDU For review of this and other power point presentations after completion of your course, please visit me at: authorstream.com Channel: paramedicedu

Thank you!:

Thank you! Pictures from: Course Text-Bob Page: 12 Lead ECG Interpretation textbook, Barbara Aehlert : ECG Made Easy & Paramedic Practice Today, Microsoft clip art, and Personal ECG stock

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