Leads, Leads and More Leads….

The question is..

where does this all “lead” us?

Silver Cross EMS Continuing Education1st Trimester January 2013

By Laurie Carroll, RN, Adventist Bolingbrook Hospital Silver Cross EMS Education Staff.

Our Agenda Today

• System announcements• Cardiac anatomy and physiology• EKG review (ALS)• 12-lead review (ALS)• Mini-CME: Autism

Silver Cross EMSS announcements

• New 1st Quarter Region 7 QA – 12 lead use. – Consider 12-leads for:

• Chest/arm/jaw/back pain (non-trauma)• Unexplained diaphoresis• Vomiting w/o fever or diarrhea• SOB/dizzy/syncope/weakness/fatigue• Epigastric pain (non-trauma)• Unexplained fall in elderly• Unexplained brady/tachy

– And document your decision to use/not use

Cardiac Anatomy Review

The Heart• Four chambers• Hollow• Muscular• Dual Circulation

– feeds the heart muscle itself– circulates blood outside the

heart• lungs for oxygenation and

CO2 offload• peripheral supply to

tissues, organs and organ systems

Right Heart• Receives unoxygenated

blood from– systemic circulation

• vena cavae– coronary circulation

• coronary sinus

• Blood passes from – right atrium– through tricuspid valve– right ventricle– pulmonic valve– pulmonary artery– to lungs

Left Heart

• Receives oxygenated blood from pulmonary vein

• Blood passes from – left atrium– mitral valve– left ventricle– aortic valve– aorta

Aorta• Oxygenated blood in the

aortic root enters the coronary arteries

• Most myocardial blood supply occurs during diastole– the aortic valve leaflets are

closed and do not obstruct the coronary artery roots

– the subendocardial blood vessels are not compressed (as they are during systole) allowing blood to flow into the myocardium itself

– in the normal cardiac cycle, diastole is longer than systole

Coronary Artery Disease• Any narrowing of the

coronary arteries causes– diminished blood supply– restriction of delivery of

electrolytes and nutrients

Who Supplies What? 

It is often helpful to understand where the supply of blood is

coming from, to help us understand which areas of the heart are affected

by various strictures/occlusions.

LCA• Left

– Left main divides into two branches

– Left Anterior Descending (LAD)• Anterior wall of LV• RBB and portions of LBB• Associated with Anterior Wall

MI– Circumflex (Cx)

• Lateral and Posterior walls of LV

• Left atrium• SA node in ~ 30%• Associated with Lateral Wall MI

RCA RightRight

Right Atrium (RA)Right Atrium (RA) Right Ventricle (RV)Right Ventricle (RV) Inferior and Posterior LVInferior and Posterior LV SA node in ~60%SA node in ~60% AV nodeAV node Associated with Associated with

right ventricular MI right ventricular MI or or dysrhythmias affecting dysrhythmias affecting SA and AV nodesSA and AV nodes

Area of Injury

• Infarct = dead or necrosis

• Blockage = causes ischemia

Collateral Circulation

• If coronary artery disease and stenosis develop slowly, collateral circulation can develop

• When the stenosis is acute, collateral circulation does not have time to develop

Cardiac Rhythm Disturbances

• CO (cardiac output) = HR (heart rate) x SV (stroke volume)

• Rhythm disturbances can hamper delivery of blood to the myocardium

Normal ECG ReviewP wave

Smooth, rounded, upright

P-R Interval.12 - .20 seconds

QRSSymmetrical< .10 seconds

S-T SegmentIsoelectric

T waveUpright, rounded

 

Hook ‘em up: Where do the stickies go,

and why?

A lead is a record of electrical activity between two electrodes. Each lead records the average current flow at a specific time in a portion of the heart.

•Skin preparation: dry, hair-free

•Placing the electrode. Be sure that the electrode has adequate gel and is not dry.

 

Trouble shooting EKG Clarity

• Equipment Grounded?• Cables attached?• Patient in reclining or semi fowler position?• Patient sitting still?• Skin clean and dry?• Limb leads in place or reversed?

There are three kinds of leads:

•Standard Limb Leads •Augmented Leads •Precordial Leads

Standard Limb Leads (Remember: “lead” may refer to a direction, or placement.)

•Lead I: The positive lead is above the left breast or on the left arm and the negative lead is on the right arm.Records the difference of potential between the Left arm and Right arm.

•Lead II: The postive lead is on the left abdomen or left thigh and the negative lead is also on the right arm.Records the difference of potential between the left leg and the right arm.

•Lead III: The postive lead is also on the left abdomen or left lower lateral leg but the negative lead is on the left arm.Records the difference of potential between the left leg and the right arm.

Augmented Leads

•The four limb leads go on the four extremities as follows: The upper extremities need placement of the electrodes

on the area of the lateral humoral aspect of the arms.

The lower extremities need placement of the electrodes on the lateral lower legs near the lateral mallelous.

•Lead aVR faces the heart from the right shoulder and is oriented to the cavity of the heart.

•Lead aVL faces the heart from the left shoulder and is oriented to the Left Ventricle. •Lead aVF face the heart from the left hip and is oriented to the inferior surface of the Left Ventricle.

Precordial Lead Placement• v1 - 4th ICS, R sternal border• v2 - 4th ICS, L sternal border• v3 - midway between v2 & v4• v4 - 5th ICS, L MCL• v5 - 5th ICS, between v4 & v6• v6 - 5th ICS, L mid-axillary line

TipSome find it easier to putthe leads on in this order v1, v2,

v4, v6Then v3 and v5

You Lookin’ at Me?It is important to look at

contiguous leads to determine which area of the heart is

affected. Each lead is like a camera lens that “looks” at an

area of the heart.

And how do I know if I have the leads in the right place?

If everything in Lead I (P, QRS & T wave) is inverted, RA and RL are reversed.Watch for the progression of the R wave in the precordial leads.

“R” WAVE PROGRESSION•The right ventricle depolarizes faster than the left ventricle because it is smaller. •The left ventricle sits to the left and posterior to the right ventricle. •As current spreads leftward through the left ventricle, the height of the R wave in the precordial leads progressively increases. •Normally, in V1 the R wave is more

negative and as it progress to V6 the R

wave becomes more positively deflected.•“R” wave progression indicates that current is flowing normally through the anterior plane of the heart. (Conover)

 

ECG Patterns• As contiguous leads look at different

parts of the heart, you may see an ischemic pattern that covers a large area or border area between two regions.

– For example, if there is ST-segment elevation in leads II/III/aVF/V5/V6, the ischemia appears to be on both the inferior and lateral areas, referred to as inferolateral.

– Likewise, there are anterolateral and anteroseptal (like the illustration here) ischemic patterns.

• What is an ischemic pattern? The AHA cites “typical ST-segment elevation” as “> 1 mm in 2 or more contiguous leads”

Injury=Elevated ST segment

•Signifies an acute process; ST returns to baseline with time •Location of injury can be determined in same manner as infarct location

•Usually associated with reciprocal ST depression

in other leads •If ST elevation is diffuse and unassociated with Q waves or reciprocal ST depression, consider pericarditis

Anterior MILAD

•Most lethal with highest mortality•Can suddenly develop CHB, VF, VT•If present with hemiblocks or BBB, •Can extend to septum and/or lateral

walls•Nitrates are desired over fluids

 

Anterior Infarction

Anterior Infarction

•ST elevation without abnormal Q wave •Usually associated with occlusion of the left anterior descending branch of the left coronary artery (LCA)

 

Lateral or Septal Wall MI

Rarely seen alone, usually an extension of anterior or inferior MI

Septal – Left Anterior DescendingLateral – Left Circumflex

Pre Intervention Post Intervention

Lateral Infarction

Inferior Wall

• RCA• The most common type of MI• Nausea is common • Frequent re-infarction or extends to lateral wall• SA / AV node• SB, sinus arrest, HB - 1st or 2nd degree AV blocks, PVC’s• Nitrates if BP stable• Medical control may ask crew to hold nitro for inferior wall MI

until right sided infarct is ruled out.

Pre PCI Post PCI

•ST elevation with/without abnormal Q wave Usually associated with right coronary artery

(RCA) occlusion

Inferior Infarction

Right Ventricular MI

• Rare• RCA • LAD or Left circumflex could also cause• Right sided heart failure• Fluids – JVD with hypotension• Watch for inferior wall MI too!

Right Ventricular Infarction

•Usually accompanies inferior MI due to proximal occlusion of the RCA

•Best diagnosed ST elevation in lead V4R •An important cause of hypotension in inferior MI recognized by

jugular venous distension with clear lung fields Aggressive therapy is indicated including:

reperfusion, adequate IV fluids for right heart filling, and pacing to maintain A-V synchrony

Posterior Wall

• RCA • Left Circumflex• Seen with Inferior or lateral wall

Posterior Infarction

•Tall, broad (>0.04 sec) R wave and ST depression in V1 and V2 (reciprocal changes)

•Frequently associated with inferior MI •Usually associated with obstruction of

RCA and or left circumflex coronary artery

Reciprocal Changes

Region of ST Elevation

Region of ST Depression

Anterior (leads V1-V4)

Inferior (true posterior)

Inferior (leads II, III, aVF)

Anterior (leads V1-V3 or lateral lead 1. aVL)

Lateral ( leads I, aVF, V5, V6)

Inferior ( leads II, III, aVF)

True Posterior Anterior (leads V1-V3)

Making the accurate Field Diagnosis:

•There are elevations (1 mm) in two contiguous or connecting leads:

(Leads adjacent to each other)•There is at least one lead with reciprocal

changes.. Reminder: •ECG would have changes in the area where the heart is being affected.• All other areas would look normal, without elevation or depression unless there is an "old MI." •In that case, the prior damage would show up as a depressed segment.

Treat The Patient…Not The Monitor

• If the patient’s symptoms do not match the ECG, you need to do more detective work

• ECG is “nondiagnostic” in ~ 50% of patients with chest discomfort

#1

12 Lead Review

#1

Normal 12 Lead / #1

#2

Acute Anterior Lateral Acute Anterior Lateral Infarct/ #2Infarct/ #2

#3

Anterolateral Infarct/ #3Anterolateral Infarct/ #3

#4

Acute Inferior Wall Infarct Acute Inferior Wall Infarct / #4/ #4

#5

Inferior Wall MI / Afib / #5

The EKG reveals an irregularly irregular rhythm suggestive of atrial fibrillation. The rate is variable, with a controlled or slow ventricular response. The axis is physiologic. ST-T changes suggestive of ischemia/ injury are present in leads II, III, and aVF. ST elevation of >1mm in limb leads is indicative of a possible inferior wall myocardial infarction. Reciprocal changes are seen in leads one and aVL.

#6

Anterio-lateral / #6

A 55 year old man with 4 hours of “crushing” chest pain.

A 55 year old man with 4 hours of “crushing” chest pain.

Acute inferior myocardial infarction (with reciprocal changes)

ST elevation in the inferior leads II, III and aVF

reciprocal ST depression in the anterior leads

A 63 Year Old woman with 10 hours of chest pain and sweating

Can you guess her diagnosis?

A 63 Year Old woman with 10 hours of chest pain and sweatingCan you guess her diagnosis?

Acute anterior-lateral myocardial infarction

ST elevation in the anterior leads V1 - 6, I and aVL

reciprocal ST depression in the inferior leads

Conduction Abnormalities

Bundle Branch BlocksRight Bundle Branch Block

Right Bundle Branch Right Bundle Branch BlockBlock

Pre PCI Post PCI

Mini-CME: Autism

• Many patients we encounter in EMS have some form of autism or fall somewhere on the autism spectrum of disorders.

• This month, please register for and complete the course Autism 101, found at: http://www.autism-society.org/living-with-autism/how-we-can-help/online-courses.html#autism101

• Submit the completion certificate to your EMS coordinator (or Silver Cross EMSS Operations if you are an independent provider).

•Thank you!

•Any further questions? If you are viewing the live presentation, please feel free to type them in the message box now. •Otherwise, feel free to call or email the EMS office or visit our website, ww.silvercrossems.com.