EKG Conferences – 2019 - 2020Steven R. Lowenstein, MD, MPH

ECG TOPICS• INFERIOR MI

• Anterior MI

• Posterior MI

• Shortness of breath

– PE, tamponade,

myocarditis, COPD

• Confusing conditions

– ST↑ and ST↓

• Review (Unknowns)

• Atrial fibrillation

• Supraventricular

tachycardias

• Wide complex

tachycardias

• Heart block and SCSD

• Syncope

• Review (Unknowns)

Year 2

Emergency physicians must advance beyond the stage of “competent”

electrocardiographer. Basic competence is not sufficient. Front-line

emergency physicians must recognize … acute myocardial infarctions in

their early, subtle stages when they are not obvious. It is not enough that

the emergency physician is able to recognize an acute inferior wall myocardial

infarction when there are 7 mm “tombstone” ST-segment elevations in the

inferior leads. Expert diagnosticians recognize that ST-segment

straightening in lead III may be the only abnormality that warns of an

impending infarction, and that isolated depression of the ST-segment in

aVL may also herald the development of an inferior wall STEMI. A critical

objective is to enable emergency physicians to make life-saving diagnoses

before others can.

ecgtracings.com

37 y.o. man with chest pain and diaphoresis

It’s not just about II, III and aVF

• Lead aVL – clue to early, not-so-obvious IMI

• 3 key complications – ECG findings that

change prognosis and management

– A-V block

– Posterior wall involvement

– Right ventricular infarction

• Predicting the culprit artery

• Detecting IMI early, and in challenging

conditions

The monitoring limb leads

Is it Normal Sinus Rhythm ?

50 y.o. female with acute

chest tightness;

Admitted as “possible MI”

The importance of aVL

• ST depression in aVL … is found in the majority of

patients with evolving inferior wall myocardial infarction

and … may be the sole ECG sign of the inferior MI.

Transient ST depression in aVL is a sensitive, early ECG

marker of acute IMI.

» Birnbaum, 1993

• Whenever a change resembling this is found in aVL in a

patient under suspicion of angina pain, that patient

should be kept under wraps until the diagnosis is

clarified.

» Marriott, 1997

When aVL shows ST-

depressions• Subtle ST-elevation in lead III is real

– A STEMI

– Cath lab activation

• May be the earliest ECG evidence of STEMI

• It cannot be acute pericarditis

• It cannot be early repolarization pattern

New Patient: 56 Y.O. man with chest pain

•Describe this M.I.

V1

Lead III Lead II

aVL

PDA → branch to

post-medial

papillary m.

Complications of Inferior STEMI: The Big Three

The Big Three Complications: Cases

63 Y.O. man with 1 week

exertional C.P. & SOB,

now at rest

35 Y.O. man with severe chest pain, radiation to jaw,

N/V, SOB; MR murmur. Alert with stable vital signs.

RIGHT-SIDED LEADS

DIFFERENT CASE

52 Y.O. man with bilateral arm pain/numbness,

fullness in throat. Also nausea, diaphoresis

Sinus tachycardia

DIAGNOSIS?

Diagnosing RVMI

CLINICAL

• Triad: Hypotension, JVP

elevation, clear lungs

– Variable, depends on

patient’s volume status and

LV function

– Sometimes: S3 gallop,

tricuspid insufficiency are

variable

• Severe hypotension after

nitroglycerin

ECG

• V4R ST-elevation in patient

with inferior STEMI

– 80-90% specific & sensitive

– Often transient; if last > 6 hours,

→ more RV dysfunction

– Identifies subset w/ 7-fold ↑↑

rate of shock, mortality

– Identifies ↑ need for reperfusion

– Helps avoid complications

during treatment

30-50% of IMI patients have an RVMI

Treatment principles• RVMI impairs RV systolic and diastolic function

– Under-filling of LV and decreased cardiac output

• Maximize RV filling and systolic function

– Avoid nitrates, diuretics, opiates

– Administer 200-300 cc boluses of fluids

– Dopamine or dobutamine (5 mcg/kg/min) are effective

• Correct bradycardia/heart block (often co-exist):

• Worsen pump failure: ischemic RV has fixed stroke

volume and RV output is entirely rate dependent.

– IMMEDIATE coronary artery reperfusion

– Long-term prognosis is good (RVMI a misnomer)

• Right ventricle is thin-walled with low 02 demand;

• Coronary perfusion in diastole + systole

• Lower RV afterload

•With excessive fluid administration:

– Dilated RV bulges into inter-ventricular septum and

impairs LV filling and decreases cardiac output.

– UpToDate: Septum intrudes into volume-deprived L.V.

Miscellaneous complications of

R.V. Infarction• Tricuspid regurgitation

• RV thombus and pulmonary embolism

• Increased right atrial pressure → A.Fib.

• RV is thin-walled

– Increased incidence of pericarditis

– RV rupture

51 Y.O. Man with chest pain

AV Block in Inferior STEMI

• 20-30% of patients

• AV-node ischemia

• 1st, 2nd, 3rd – degree

• Transient, variable

need for pacing

• Usually responds to

atropine (intra-nodal)

• Often narrow-

complex escape

• Accelerated

junctional rhythm

(NPJT)

IMI: The patient in shock

• AV block, bradycardia

• RV Infarction (impaired preload)

• Extensive LV dysfunction (inferior-posterior-

lateral MI)

• Papillary muscle rupture

– Postero-medial papillary muscle rupture most common

– Single blood supply from posterior descending artery

– Don’t miss mechanical cause of cardiogenic shock

Papillary Muscle Rupture

• Can be devastating – Is a mechanical cause of

cardiogenic shock

– Accounts for 5% of mortality from MIs

• More common with inferior MI, usually occurs days 2-7

and incidence likely lower with lytics and PCI treatments

• Posteromedial papillary muscle more commonly

involved, due to single blood supply (PDA)

• Anterolateral papillary muscle supplied by both the

LAD and Left Circumflex

• Often (not always) hear a pansystolic murmur; dx is

easy with ECHO

• Treatment with vasodilators and often IABP bridge

Less Obvious Inferior Infarcts

55 Y.O. man with intermittent chest

pain and mild dyspnea

41 Y.O. female with 3 days of chest pain, cough – she attributed

symptoms to sitting in front of computer all day. “Mild discomfort,

slightly anxious.”

DIAGNOSIS?

17 minutes later

•BER

•Pericarditis

•Normal men

•LVH

Acute M.I.

• DOES THE SHAPE OF THE ST-SEGMENT MATTER?

• Sure.

• Regional pattern & reciprocal changes matter more

Predicting the Culprit Occlusion

• RCA clot in ~ 85%

• Injury current directed

inferiorly and rightward

– Toward lead III

– Away from lead II, aVL

– ECG usually shows:

• ST-elevation III > II

• Marked (> 0.1 mV) ST-

depression in aVL, I

• Higher likelihood of

– RVMI and AV block

– In-hospital complications

Circumflex

and

obtuse

marginal

III II

aVL

V5-6RCA

Predicting the Culprit Occlusion

• Left Circ clot in ~ 15%

• Injury current directed

inferiorly leftward

– Toward lead II and aVL, I

– Away from lead III

• ECG may show:

– ST-elevation II > III

– Minimal ST-depression in

aVL or even ST-elevation

– ECG changes of posterior

or lateral STEMI

Circumflex

and

obtuse

marginal

III II

aVL

V5-6RCA

37 year-old man without medical history, presented with severe sub-sternal

chest pain radiating to left arm and throat, shortness of breath. (Intake ECG)

ECG taken 18 minutes later. First troponins: 0.00 and 0.02.

Special diagnostic challenges

53 yo man presented with right-sided chest pain after minor MVC.

ECG obtained because he “didn’t feel good or look good.”

•~ 60 YEAR-OLD MAN PRESENTED IN CARDIAC ARREST

•RHYTHM STRIP TAKEN DURING 1 HOUR OF ATTEMPTED

RESUSCITATION FROM CARDIAC ARREST

63 Y.O. man with chest pain, SOB; WBC=18,000; Dx in ED with pneumonia.

Initial troponin=0.3. ED note: EKG shows RBBB and possible anterior ischemia

and indeterminate trop – we will treat him for ACS and Non-STEMI

75 year-old female with a syncopal episode at DIA. Asymptomatic in ED;

examination normal except for forehead laceration

REVIEW TRACINGS

54 y.o. man from New York, with hypertension, diabetes,

hypercholesterolemia. Had intermittent SSCP for two months, then acute,

severe pain for past 4 hours.

47 year old man with chest pain, some radiation to arms and

right jaw, resolved after ASA, then returned.

89 year old man with dyspnea and confusion

79 y.o. female with a history of hypertension, c/o chest pain, shortness of breath,

diaphoresis. Awoke with severe substernal pressure at 3AM, with nausea.

59 y.o. female, history of IDDM, graves disease, awoke with chest pain at

4AM, presented to ED 5 hours later.