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ONTARIO BASE HOSPITAL GROUP Chapter 12 for 12 Lead Training -STEMI MimicsOntario Base Hospital Group Education Subcommittee 2008 TIME IS MUSCLE STEMI Mimics AUTHOR REVIEWERS/CONTRIBUTORS Greg Soto, BEd, BA, ACP Neil Freckleton, AEMCA, ACP Hamilton Base Hospital Niagara Base Hospital Jim Scott, AEMCA, PCP Sault Area Hospital Ed Ouston, AEMCA, ACP Ottawa Base Hospital Laura McCleary, AEMCA, ACP SOCPC Tim Dodd, AEMCA, ACP Hamilton Base Hospital 2008 Ontario Base Hospital Group Dr. Rick Verbeek, Medical Director SOCPC OBHG Education Subcommittee STEMI Mimics: Say what? K Mimics in 12 Lead ECG interpretation refer to physical or electrical factors that can make interpretation difficult. K Also referred to as imitators, mimickers and maskers K These factors can either hide or mimic ECG patterns consist with an ACS OBHG Education Subcommittee Mimics – The List a. b. c. d. e. f. g. Bundle Branch Blocks Left Ventricular Hypertrophy (LVH) Electrolyte disturbances Digitalis effects Pericarditis Benign Early Repolarization Pacemaker rhythms OBHG Education Subcommittee ONTARIO BASE HOSPITAL GROUP a. Understanding Bundle Branch Blocks a. Objectives K Describe the properties of the intraventricular conduction system K Describe the clinical and reperfusion relevance for BBB identification K Using turn signal method, determine the presence and location of bundle branch block K Describe the hemodynamic and conduction system problems associated with a bundle branch block OBHG Education Subcommittee Bundle Branch A&P K Block of left or right bundle branch K Fascicle of the conduction system K “Functional syncytium” K Bundle branch blocks = ventricles out of sync OBHG Education Subcommittee Pathophysiology of BBB K Caused by ischemia acutely K Can be a result of congenital defects K Can be secondary to hypertension or degenerative heart disease K Some people live with a BBB and the limitations OBHG Education Subcommittee Bundle Branch Block (BBB) K New z or presumably new Candidate for acute reperfusion therapy K How do we know it is a new onset? K May mask or mimic acute ECG changes K How do we triage and treat? OBHG Education Subcommittee What happens in a BBB? K Unaffected bundle branch depolarizes normally K Diseased bundle branch does not deliver the impulse to the ventricle K Wave of depolarization is spread from the unaffected side, cell to cell, to the other ventricle K It takes longer to depolarize in this fashion, so the QRS is widened as a result OBHG Education Subcommittee BBB Identification KSupraventricular rhythm in origin KWide QRS (120ms or more) OBHG Education Subcommittee Diagnosing BBB K Use VI K Circle the J point K Find the terminal deflection K Shade in an arrowhead pointing up or down K Apply “turn signal” criteria OBHG Education Subcommittee Real-world step by step From ECG interpretation or initial 12 lead look you will likely find wide looking QRS with notching 2. This should clue you into look for QRS duration in 12 Lead info section at top of printout 3. Determine LBBB or RBBB in a wide complex SVT by using VI 1. OBHG Education Subcommittee Example: LBBB OBHG Education Subcommittee Example: LBBB OBHG Education Subcommittee Example: RBBB OBHG Education Subcommittee Example: RBBB OBHG Education Subcommittee Practice Cases Bundle Branch Blocks OBHG Education Subcommittee Left BBB OBHG Education Subcommittee Right BBB OBHG Education Subcommittee Incomplete Left BBB OBHG Education Subcommittee Left BBB OBHG Education Subcommittee Right BBB OBHG Education Subcommittee Right BBB OBHG Education Subcommittee Left BBB OBHG Education Subcommittee Right BBB OBHG Education Subcommittee Left BBB OBHG Education Subcommittee Right BBB OBHG Education Subcommittee Left BBB OBHG Education Subcommittee Left BBB OBHG Education Subcommittee Clinical Significance of BBB KBBB caused by AMI z 60%-70% association with pump failure z 40%-60% mortality without reperfusion OBHG Education Subcommittee Clinical Significance of BBB KCan mimic ACS KCan hide evidence of ACS OBHG Education Subcommittee Bundle Branch Block K May Produce z ST elevation z ST depression z Tall T waves z Inverted T waves z Wide Q waves K May Hide z ST elevation z ST depression z Tall T waves z Inverted T waves z Wide Q waves OBHG Education Subcommittee The Solution Lives Saved (per 1 ,0 0 0 ) Fibrinolytic Therapy Trialists’ (FIT) Collaborative Group, 1994 OBHG Education Subcommittee The Problem K Critical to reperfuse patients with new or presumably new BBB produced by ACS K ACS harder to identify on ECG when BBB present (how do you know it is new?) OBHG Education Subcommittee Clinical Significance of BBB KCan mimic ACS KCan hide evidence of ACS KUsually not to be trusted! OBHG Education Subcommittee The Solution New or presumably new BBB is an indication for thrombolytic therapy z Base your triage decision on the patient presentation. i.e.: on suspicion of AMI z CTAS with hospital notification - not necessarily a Cardiac or STEMI Alert OBHG Education Subcommittee ONTARIO BASE HOSPITAL GROUP b. Left Ventricular Hypertrophy (LVH) b. Objectives KIdentify evidence of left ventricular hypertrophy and strain KDescribe the clinical implications of ventricular enlargement OBHG Education Subcommittee Left Ventricular Hypertrophy K LVH-increased pressure or volume K Found in mitral and aortic stenosis, cardiomyopathy, hypertension, IHD K Experts disagree on ECG accuracy K Nonetheless, the criteria are proven K Definitive Dx: echocardiography OBHG Education Subcommittee LVH Voltage Criteria – Rule of 35’s K If they add up to more than 35 mm, and the patient is over 35 years old, then voltage criteria for LVH is met K Measure deepest S wave in either V1 or V2; add to tallest R wave in V5 or V6 K Look for aVL pattern K Then look for “strain” OBHG Education Subcommittee LVH Voltage Criteria 17 26 OBHG Education Subcommittee LVH Voltage Criteria KR wave in aVL is >11 mm OBHG Education Subcommittee Strain Pattern Ka pattern of asymmetrical ST depression & Twave inversion most commonly seen in V5 & V6 (sometimes in I, aVL, V4) K Increases sensitivity of voltage criteria for LVH OBHG Education Subcommittee Why high amplitude QRS in LVH? K voltage of QRS complex is proportional to amount of muscle being depolarized K higher voltage suggests overgrowth of muscle in that chamber K LV larger muscle mass = larger pattern in QRS OBHG Education Subcommittee LVH w/strain – rule of 35 OBHG Education Subcommittee LVH w/strain – rule of 35 OBHG Education Subcommittee None OBHG Education Subcommittee LVH w/strain/aVL > 11mm OBHG Education Subcommittee None OBHG Education Subcommittee LVH – aVL > 11mm OBHG Education Subcommittee ONTARIO BASE HOSPITAL GROUP c. Electrolyte Disturbances Page, 12-Lead ECG for Acute and Critical Care Providers © 2006 by Pearson Education, Inc. Upper Saddle River, NJ c. Objectives K List the causes and clinical implications of various electrolyte abnormalities K Describe ECG changes in hyperkalemia & hypokalemia OBHG Education Subcommittee Effects of Potassium K Potassium (K+) Prevents shortened action potential z Allows for organized fast heart rates z Protects from excitability z Slows heart in vagal responses z OBHG Education Subcommittee Hyperkalemia K K 1. 2. 3. Hyperkalemia is a potentially lifethreatening metabolic problem Caused by: inability of the kidneys to excrete potassium impairment of the mechanisms that move potassium from the circulation into the cells or a combination of these factors. OBHG Education Subcommittee Hyperkalemia K Symptoms are fairly nonspecific, and generally include malaise, palpitations and muscle weakness K SOB may indicate metabolic acidosis K Potentially life-threatening problem K Lethal injection: Along with pancuronium (NMB) and thiopental, potassium chloride is used in 37 states of the US to execute prisoners. OBHG Education Subcommittee Hyperkalemia K Serum levels above normal range K Most common cause is renal failure K Sinus node can quit at 7.5 mEq/L K VF or asystole at 10–12 mEq/L OBHG Education Subcommittee Hyperkalemia – ECG K Tall T waves with a narrow base K QRS widens K Broad S waves in V leads OBHG Education Subcommittee Hyperkalemia – ECG K ST segment disappears K “T wave grows, P wave goes” K Sine waves in severe cases OBHG Education Subcommittee Hypokalemia K Serum level below 3.5–5.0 mEq/L K Caused by vomiting, diarrhea, diuretics, gastric suctioning K Hypomagnesemia K Muscle weakness, polyuria K Digitalis can take advantage and cause Torsades de pointes OBHG Education Subcommittee Hypokalemia K ECG Changes ST segment depression z T waves flatten or join U waves z U waves get larger than Ts z QT interval appears to lengthen z PR interval increases z OBHG Education Subcommittee Hypokalemia K Potassium KU normal waves overtake T OBHG Education Subcommittee ONTARIO BASE HOSPITAL GROUP d. Digitalis Effects d. Objectives KRecognize the signs and symptoms of digitalis toxicity KDescribe the ECG criteria for digitalis effect OBHG Education Subcommittee Digitalis Toxicity K also known as digoxin and digitoxin (trade name = Lanoxin) K strengthens contraction of the heart muscle K slows the heart rate (via PNS stimulation) K helps eliminate fluid from body tissues K used to treat congestive heart failure and is also used to treat arrhythmias such as Atrial Fib. K derived from the foxglove plant OBHG Education Subcommittee Digitalis Toxicity K Potential for serious adverse effects K Narrow window between therapeutic & toxic effect S&S of toxicity: K Headache, nausea, vomiting, diarrhea K Altered colour perception: halo vision K Generalized malaise, delirium OBHG Education Subcommittee 12 Lead & Digitalis Effect K K K K K 60% of those on “Dig” have it ST segment depression Scooped out appearance Best seen in inferior/lateral leads Not pathologic but result of dig toxicity OBHG Education Subcommittee Digitalis effect OBHG Education Subcommittee ONTARIO BASE HOSPITAL GROUP e. Pericarditis e. Pericarditis K Describe the pathology and pattern of signs and symptoms K Demonstrate the assessment steps to recognized pericarditis K Describe ECG evidence of pericarditis pacemaker rhythms early repolarization OBHG Education Subcommittee Pericarditis K Inflammation of the pericardium K Occurs in younger patients without history of CAD K You should pick this up from assessment more than 12 Lead ECG interpretation OBHG Education Subcommittee Normal Pericardium OBHG Education Subcommittee Causes of Pericarditis K Infection: viral, bacterial, fungal, parasitic K Ideopathic K Neoplastic K Immune disorder K Traumatic K Iatrogenic: CPR, radiation injury, instrumentation, drugs OBHG Education Subcommittee Pericarditis K Signs and Symptoms Chest pain, dyspnea, tachycardia, fever, weakness, chills z Chest pain sharp, radiating to back, neck, jaw z Made worse by lying flat, twisting z Made better by leaning forward z OBHG Education Subcommittee Pericarditis K Often pleuritic pain, worse on inhalation K Pain can last for hours or days K Pericardial friction rub z Heard over left lower sternal border OBHG Education Subcommittee Pericarditis ECG Criteria K ST segment elevation K Concave in all leads K T wave elevation K PR depression OBHG Education Subcommittee Pericarditis OBHG Education Subcommittee Pericarditis: Diagnosis Physical Criteria: (CP, relieving criteria, pleuritic) z No response to NTG z Pericardial rub z ECG changes that do not localize z OBHG Education Subcommittee ONTARIO BASE HOSPITAL GROUP f. Other STEMI mimics Ventricular Rhythms Paced OBHG Education Subcommittee Early Repolarization K Occurs in young, healthy people K African American males K Notched J point K Concave elevation K Leads II, III, aVF, V4–V6 K Lateral leads OBHG Education Subcommittee Benign Early Repolarization • Look for notch at J-point – ST segment and J-point create a “fish hook” appearance OBHG Education Subcommittee Benign Early Repolarization OBHG Education Subcommittee ONTARIO BASE HOSPITAL GROUP PRACTICE ECGs AFib w/ PVCs and RBBB OBHG Education Subcommittee A Fib w/ RBBB OBHG Education Subcommittee Hyperkalemia OBHG Education Subcommittee NSR – No STEMI OBHG Education Subcommittee NSR – Extensive Anterior AMI OBHG Education Subcommittee NSR w/ LVH w/strain OBHG Education Subcommittee NSR – old Septal MI OBHG Education Subcommittee S Brad – Lateral STEMI w/RCs OBHG Education Subcommittee NSR w/LBBB OBHG Education Subcommittee BER OBHG Education Subcommittee NSR – Inferior STEMI 15 lead OBHG Education Subcommittee SVT w/RBBB OBHG Education Subcommittee 1st° Block w/PVCs – RBBB OBHG Education Subcommittee NSR – Inferior STEMI w/RCs = 15 lead OBHG Education Subcommittee LVH – rule of 35 OBHG Education Subcommittee NSR, digitalis effect, prolonged QT OBHG Education Subcommittee 2nd° Type I - LBBB OBHG Education Subcommittee LBBB OBHG Education Subcommittee A Fib – RBBB OBHG Education Subcommittee Pericarditis OBHG Education Subcommittee NSR – old Inferior MI OBHG Education Subcommittee 3rd° block – broad Ischemia OBHG Education Subcommittee S Brad – Anteroseptal & Inferior STEMI OBHG Education Subcommittee ONTARIO BASE HOSPITAL GROUP QUESTIONS? ONTARIO BASE HOSPITAL GROUP Well Done! Education Subcommittee START QUIT