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ECG Interpretations in Anesthesiology
Brian C. Weiford M.D., FACCPostgraduate Symposium on
AnesthesiologyApril 11, 2014
ECG Interpretations for the Anesthesia Professional
• ECG skills are valuable at every phase of the continuum of care– Preoperative: PAT clinic, etc– Intraoperative– Postoperative
Topics
• The normal ECG• Arrhythmias
– Ectopy– Supraventricular– Ventricular
• Coronary Ischemia, Injury, and Infarct• Pacemakers• Miscellaneous fun with ECGs
Components of the ECG - ReviewP – Wave: Atrial Depolarization.
• Can be positive, biphasic, negative.
QRS Complex: Ventricular Depolarization.
• Q – Wave: 1st negative deflection wave before R-Wave.
• R – Wave: The positive deflection wave.
• S – Wave: 1st negative deflection wave after R – wave.
T – Wave: Ventricular Repolarization.
• Can be positive, biphasic, negative.
Normal Sinus Rhythm with Normal ECG Normal variant Juvenile T wave pattern
From Braunwald’s Heart Disease, 7th Ed.
Sinus Arrhythmia/Dysrhythmia
Two forms of Sinus Dysrhythmia: 1) more commonly, due to respiratory variability and changes in
vagal tone
2) In elderly subjects with heart disease, and probably related to sinus node dysfunction
Sinus Bradycardia
•Sinus rate < 60 bpm, but usually not clinically significant unless < 50 bpm•Sinus rate is usually > 40 bpm in normal subjects•HR < 40 bpm can be seen commonly in normal subjects during sleep and in well-trained athletes•Sinus rate affected by numerous medications
•Beta blockers, calcium channel blockers, digoxin, antiarrhythmics, clonidine, neostigmine, etc.
•For sinus rates < 40-50 in the absence of medications:•consider sinus node dysfunction (SSS), hypothyroidism, hypothermia, ischemia, and infarction.
Sinus Tachycardia
•Most often, a physiologic reactive phenomenon (to extracardiac stimuli: e.g., hypotension, pain, fever, hypoxia, anemia, anxiety, thyrotoxicosis, etc)•Rarely, “inappropriate sinus tachycardia” observed, with elevated resting sinus rate and exaggerated acceleration of sinus rate with physiologic stimulation.
•Can be treated with radiofrequency ablation/SN modification
Sinus Tachycardia
• Age predicted maximal HR (APMHR) = 220-age
• That rate can be exceeded in intense physiologic exercise, stress, or exaggerated adrenergic stimulation
• Differentiation from supraventricular dysrhythmias (atrial tachycardia, Aflutter) can sometimes be challenging
Premature Atrial Complexes (PACs)
• A supraventricular impulse that occurs earlier than expected and originates in an atrial focus, not in the SA node
• Due to increased automaticity of an atrial focus
• Typically they are clinically insignificant– Can serve as triggers for sustained
dysrhythmias like SVT or AFib/flutter
Premature Atrial Complexes (PACs)
• Based on multiple ambulatory ECG studies, PACs are common findings in healthy subjects, being observed in:– ~15% of infants <10 days old– 13% of 10-13 year old boys– Nearly 2/3 of healthy 22-28 year old women
and > 1/2 of asx male medical students– 100% of 19-29 year old long distance runners– 100% of apparently healthy octogenarians
Wagner, Marriott’s Practical Electrocardiography, 9th ed.
PAC Generation
Courtesy of St. Jude Medical
PAC Morphology
• QRS complexes, ST segments, and T waves should be normal or unchanged from baseline.
• P wave morphology will be different than sinus P wave.
• Shorter PR intervals than sinus PR interval– Due to location of the foci– Shorter routes for
their depolarization waves
Junctional beats/escape Ectopic Atrial Rhythm
Note negatively directed P wave in II
Ectopic Atrial Rhythm
• Often transient• Can occur in individuals with and without
structural heart disease• Distinguish from sinus rhythm by
comparing P wave morphologies, P wave vector
PVC(Premature Ventricular Complex)
Frequency of PVCs in General Population
• Based on the ARIC study (of almost 16000 45-65 year olds in 4 US communities), overall prevalence was– 8% in African American males– 7% in white males– 7% in African American females– 5% in white females– In older, African American males with heart disease,
prevalence ~20%– Strong association between HTN and prevalence of
PVCsSimpson: Am Heart J 2002;143:535-40
Frequency and Significance of PVCs in General Population
• In the ARIC study, there was a more than 3x increase in coronary heart disease (CHD) mortality in subjects with PVCs
• After controlling with CV risk factors and therapy, subjects with PVCs were twice as likely to die from CHD than those without PVCs
Massing: Am J Cardiol 2006;98:1609 –1612
Quadrigeminal PVCs Actual Advertisement
Functional LBBB (with underlying sinus tachycardia and HR 115 bpm)
Atrial Fibrillation with elevated ventricular response
Note irregularly irregular and rapid R-R pattern with absence of P waves
Ventricular pacing with underlying Atrial Flutter
2nd Degree AV block (Mobitz II)
•Note predominant 2:1 association of P waves and QRS complexes•Note wide complex QRS
2nd Degree AV block
• Mobitz I (Wenckebach) 2nd degree AV block can be seen in normals and in subjects with heart disease– 2nd degree AV block present in 11% of healthy 10-13
year old boys and 40% of distance runners based on holter/ambulatory ECG studies
• QRS is prolonged 80% of the time with Mobitz II block (infranodal block—within or below bundle of His)
• 2:1 AV block can be due to to a Mobitz I or Mobitz II block mechanism
Sinus rhythm with complete heart block (in setting of acute inferior MI)
Note regular R-R intervals and lack of 1:1 association with P waves (plus ST elevation in inferior leads)
Atrial Fibrillation with complete heart block
Note absence of P waves and coarse baseline with regular R-R intervals
Note marked bradycardia, scalloped/sagging ST depression in inferior leads, flattened T waves in lateral leads, and prominent U waves in V2-3.
Digoxin effect and toxicity: complete heart block with junctional escape rhythm
WPW (underlying sinus rhythm)
From Braunwald’s Heart Disease, 7th Ed.
• Aberrant conduction of supraventricular impulses. Note association of P waves with QRS
• Refractory period of bundle branches is related to preceding R-R interval. – Long-short initiation sequence finds right bundle in
refractory period and QRS is conducted aberrantly (RBBB)
• Ashman’s phenomenon– Common cause of “pseudo VT”
Multifocal Atrial Tachycardia
•Irregularly irregular tachycardia with 3 or more distinct P wave morphologies•Important to differentiate from atrial fibrillation•Highly associated with lung disease such as COPD
From Braunwald’s Heart Disease, 7th Ed.
ECG Changes in Acute Coronary Syndromes (ACS)
• ST depression = Ischemia– Digoxin effect, Repolarization changes with LVH
• ST elevation = Injury (threatened infarction)– Pericarditis, Coronary vasospasm
• Q waves = Infarction– Pseudo Q waves
Prevalence of ECG post surgery• Based on the VISION study
– New T wave inversions most common (in 23%), but not likely clinically significant
– New ST depression of > or =1mm (in 16%)– New ST elevation of > or =1mm (in 2.3%)– New LBBB (in 0.5%)
• Three findings independently associated with 30 day mortality: ST elevation, anterior ST depression, and new LBBB
• Most new ischemic ECG changes in POD#1
Biccard: Curr Opin Anesthesiol 2014, 27:000–000
Pseudo-infarct Patterns (Q-waves in absence of MI)
• WPW• Hypertrophic CM• LVH• LBBB• RVH• LAFB• Chronic lung disease• Amyloid, sarcoid, & infiltrative
cardiomyopathies• Chest deformity• Pulmonary Embolus• Myocardial contusion• Acute CNS ischemia
• Myocarditis• Myocardial tumors• Hyperkalemia• Pneumothorax• Pancreatitis• Lead reversal• Corrected transposition• Muscular dystrophy• Mitral valve prolapse• Left/right atrial enlargement• Atrial flutter• Dextrocardia
Ischemia
Diffuse Ischemia Ischemia?
• 23 year old with hypertrophic cardiomyopathy• Note high QRS voltage Injury Pattern
Location in Acute ST-Segment elevation MI (STEMI)
• Anterior:- rS complex in V1 followed by ST segment elevation in leads V2-V4
• Anteroseptal:– abnormal Q or QS deflection in V1-V3 and sometimes V4 with ST
segment elevation• Anterolateral:
– abnormal Q waves with ST segment elevation in leads V4-V6• Lateral/High Lateral:
– abnormal Q wave in lead I and aVL with ST segment elevation• Inferior:
– abnormal Q wave in at least 2 of leads II, III, aVF with ST segment elevation
• Posterior:– initial R wave in V1-V2 >0.04s with R>S, and ST segment
depression (usually >2mm) with upright T waves.
Location
Diffuse Mild ST elevation: Pericarditis
Note PR segment depression in multiple leads, and PR elevation in aVR
Anteroseptal STEMI Inferior STEMI
Inferior STEMI (with probable RV involvement) Inferior STEMI (with probable posterior involvement)
Lateral STEMI Extensive Injury (posterior, inferior, lateral, and anterolateral)
True Posterior Injury/Infarct Criteria Extensive Injury (anteroseptal, anterolateral, lateral and inferior)
Extensive inferior and anterolateral STEMI
Acute MI with chronic LBBB
Single Chamber Pacing System
AAI Pacemaker VVI Pacemaker
Dual Chamber pacing
Real or Artifactual?
Thanks
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