ECG Interpretation Review #143 (ECG Guru - Dawn Altman - Dr. Stephen Smith)

     One of the reasons why I have decreased the frequency of my own ECG Blog posts — is that for the past few years I have actively been commenting on Dawn Altman’s ECG Guru site — as well as on many of the wonderful ECG posts put forth by Dr. Steven Smith on his most excellent blog site. 

For those desirous of additional sources of detailed ECG commentary — I suggest you check out:

• The Instructors’ Collection of ECGs on Dawn’s ECG Guru site.
• Any of the superb clinical cases posted on Dr. Smith’s ECG Blog.

I’ve attached below links to some of my earlier posts from both of these sites for which I’ve left detailed commentary. For anyone with a real “passion” for ECG/Arrhythmia interpretation — reading through these posts ought to keep you busy for a good while. Happy reading!

 

-------------------------------------------

NOTE (10/26/2020) — For an UPDATED version with LINKS to all of my comments on Dr. Smith's ECG Blog and on the ECG Guru site — Please LOOK for the icon in the right-hand column of any page on this web site !!!

-------------------------------------------

 

Note: Below the Figure from Dawn’s most recent Instructors’Collection ECG. I’ve added my labels in Figure-1. Detailed commentary by me supplements Dawn’s initial interpretation. Enjoy!

Figure-1: ECG from a 75yo man with new chest pain. How would you interpret this ECG? What is the “culprit” artery? Do you need the bottom ECG to tell? And, WHAT is the rhythm?

-------------------------------------------

Figure-2: Addition of labels to Figure-1 (Please CLICK HERE for my detailed analysis of this case).

-------------------------------------------

For My ECG Guru Comments:

• Selected Comments by Me on ECG Guru ...
• LBBB with almost certain LVH — Comment #441 -
• Acute Occlusion of the 1st or 2nd Diagonal — Comment 664 - 
• LBBB with some Interesting Findings — Comment #860 -
• Drawing Laddergrams — Comment #861 - #877 -
• Mobitz I or Mobitz II (RBBB) — Comment #862 -
• 99+% Likelihood of VT — Comment #866 -
• Regular SVT without sinus P waves (180/min) — Comment #867 -
• LMain Disease vs Occlusion (Using aVR) — Comment #876 -
• Acute RCA Occlusion/Retrograde Wenckebach — Comment #878 -
• AFib with Complete AV Block — or Is It? — Comment #879 -
• LVH but No History — and Anything Else? — Comment #880 -
• Mobitz 2 with 3:1 AV Conduction (+ RBBB/LAHB) — Comment #884
• AFlutter with a Variable Ventricular Response — Comment #888
• Atrial Bigeminy or Something Else? (SA Wenckebach) — Comment #973
• CHALLENGE: AFib or Sinus Rhythm with PACs? — Comment #1006
• Where does the ST "end" and the T "begin" — Comment #1010
• Rapid AFib: Effect on Cardiac Output ...  — Comment #1011
• Anterior MI with Interesting Features (? Wellens) — Comment #1012
• LADDERGRAM Review: Basic Arrhythmia Elements — Comment #1018
• A "Nearly Normal" ECG (What is "normal"? ) — Comment #1021
• AFlutter with a PVC or Aberrant Beat? — Comment #1025
• ECG Changes of Hyperkalemia (serum K+ = 7.4) — Comment #1026
• Complete AV Block at AV Nodal Level — Comment #1033
• Some Fine Points about LAHB / RBBB — Comment #1034
• RBBB plus some Subtle-but-Real Changes — Comment #1056
• SA Block — or Maybe Not? — Comment #1058
• ST Elevation MI from Which "Culprit" Artery? — Comment #1068
• LVH — Fragmentation and Strain vs Ischemia — Comment #1072
• Acute Inferior MI + Bradycardia (culprit artery) — Comment #1074
• AVRT in a 13yo with WPW (long RP' ) — Comment #1075
• Chest Pain & Giant T Wave Inversion — Comment #1081
• Does the Patient have a Pacemaker? — Comment #1086
• False Capture Pacing (Transcutaneous Pacer) — Comment #1091
• Acute Infero-Postero STEMI (Pos "Mirror" Test) — Comment #1093
• Anything Acute Going On? (subtle ST-T abns.) — Comment #1095
• AFib and Antero-Septal MI with an Early Beat — Comment #1096
• PACs with Varying Degree of Aberrancy — Comment #1099
• Assessing some Technical ECG Aspects — Comment #1102
• Mobitz I plus Dual AV Nodal Pathways — Comment #1104
• Bradycardia and Sinus Pauses in 59yo Man — Comment #1106
• Suspected 1st Diagonal Occlusion — Comment #1107
• Large Anterior MI after the Event — Comment #1108
• The Cause of Extreme QRS Widening — Comment #1178
• How I Use a Normal ECG for Teaching — Comment #1183
• Giant T Waves of Uncertain Cause — Comment #1186
• A 42yo with NSVT and Prolonged PR Interval — Comment #1187
• A Regular WCT with Atypical QRS Morphology — Comment #1189
• Acute STEMI: What a Difference 10 Minutes Make — Comment #1198 
• IVCD, ST Changes, Torsades and More! — Comment #1199
• "Aunt Minnie" with a High & Low (Lytes, renal) — Comment #1298
• Regular WCT with LBBB Morphology — Comment #1302
• Ischemia on ECG: Systematic Approach — Comment #1303
• 6th ECG in a Series (new chest pain in 87yo man) — Comment #1305
• Acute Pericarditis (not Acute MI ) — Comment #1316
• AV Block not Following the Rules ... — Comment #1321
• Differential Diagnosis of a Regular SVT — Comment #1326
• Complete AV Block in a 78yo Woman — Comment #1328
• Recognizing Rate-Related Conduction Defects — Comment #1354
• Is there "Tri-Fascicular" Block? — Comment #1356
• Is this Mobitz 1 or Mobitz 2? —Comment #1357
• Hyperkalemia on ECG (mod-to-marked ...) — Comment #1358
• Paced Tracing showing Acute STEMI — Comment #1463
• The Basics of BBB — Comment #1478 
• High-Grade vs Mobitz II 2nd-Degree AV Block — Comment #1483
• A Worrisome ECG without any History ... — Comment #1511 
• How Many Findings of Ant. STEMI are There? — Comment #1512
• Peaked T Waves in a Few Leads ... — Comment #1605
• Why Did this Patient Arrest? — Comment #1606
• An ECG Pattern to Remember (Brugada) — Comment #1608 -
• STEMI Alert Indicated Despite Wide QRS — Comment #1609 - 
• I Was Surprised by the Cath Findings — Comment #1621 -
• Acute Inf-Post-Lat MI + RBBB — Comment #1664 - 
• RBBB, LAA, Computerized ECGs — and MORE! — Comment 1796 -
• Acute RV MI (with Inf. STEMI and AV Block) — Comment #1800 -
• Is this Really High-Grade AV Block? — Comment #1809 -
• Elderly Woman with Takotsubo Cardiomyopathy — Comment #1824 -
• Atrial Pacing + RBBB + acute STEMI — Comment #1919 -
• Remember the 2 Steps in ECG Interpretation — Comment 1926 -
• Looks like STEMI/Normal Cath (myocardial bridge?) — Comment 1934 -
• Why Did this Patient Die? (What is the QTc? ) — Comment 1946 -
• Low Atrial vs Junctional Rhythm in 86yo (Peaked T) — Comment 1949 -
• More Questions than Answers (Ant. MI/PVCs) — Comment 1954 -
• Fragmented RBBB — but Nothing Acute — Comment 1956 -
• Fragmented RBBB in a Woman with Sepsis — Comment 1958 -
• Some Thoughts on a PEDIATRIC ECG — Comment 1959 -
•  A 55yo Man with Syncope + Tachycardia — Comment 1961 -
• Acute STEMI + AFib + What Else? — Comment 1963 -
• Sinus Arrhythmia in a Patient — Comment 1966 -
• Bi- vs Tri-Fascicular Block (a real term?) — Comment 1967 -
• First Check Serum K+ — THEN consider IVCD — Comment 1976 -
• Something is Wrong — But I Don't Know What! — Comment 1983 -
• A Funky Rhythm/Peaked T Waves & RBBB+ in V1 — Comment 1986 -
• Can you Localize Ischemia on ECG? (My Reply) — Comment 1992 -
• Lots of Findings to Talk About/No History — Comment 1993 -
• Acute Proximal LAD Occlusion (STEMI-LAHB) — Comment 1994 -
• Impending Ventricular Standstill (bradyarrhythmia) — Comment 1997 -
• "Shark Fin" ST Elevation — Comment 2003 -
• Is this Incomplete LBBB? (acute MI? ) — Comment 2005 -
• XXX  — XXX
•  
   

-------------------------------------------
For My Comments on Dr. Steve Smith's Blog:

• Subtle Change with Acute Inferior MI — January 7, 2012
• Which Artery? — RCA vs LAD? (Acute RV Infarct) — November 14, 2014
• Persistent Juvenile T Waves (When is it normal?) — January 7, 2015 -
• Echo before ECG for Chest Pain — January 28, 2015 -
• Not Brugada in V1,V2 — but HyperKalemia! — August 9, 2015 -
• Terminal QRS Distortion vs Early Repol (in V2,V3) — October 6, 2015 -
• LVH with Anterior ST Elevation (vs Ant. STEMI?) — December 29, 2015 -

• Chest Pain & Flu (STEMI vs Localized Myocarditis) — March 18, 2016 -
• Acute Prox LAD Occlusion (RBBB/LAHB- Lambda) — March 21, 2016 -
• A Pathognomonic ECG (long QT, peaked T — Ca++) — March 24, 2016 -
• Acute LMain Occlusion (ECG recognition) — March 26, 2016 -
• Acute STEMI despite Permanent Pacing — April 2, 2016 -
• Resuscitation Pearls / LCx vs RCA "Culprit" — April 17, 2016 -
• DeWinter-like T waves — Should NOT be Missed! — April 20, 2016 -
•    10 Examples to TEST Recognition (Ant. T Waves) — April 23, 2016 -
•    10 Examples of Inferior Hyperacute T Waves — May 1, 2016 -
• ECG Distinction between Acute PE vs Chronic RVH — May 27, 2016 -
• Fusion, Capture beats: "2 Wrongs may make a Right" — June 3, 2016 -
• RBBB and ST Elevation (new STEMI vs LV Aneurysm) — June 6, 2016 -
• Hyperacute Inferior T Waves or Reciprocal ST Changes — June 10, 2016 -
• Anterior STEMI vs Benign Early Repolarization? — June 17, 2016 -
• The Computer Missed WPW (re the Concertina Effect) — June 20, 2016 -
• Terminal QRS Distortion with Acute LAD Occlusion — June 24, 2016 -
• Acute Inferior STEMI — or Is It? — July 1, 2016 -
• Acute Anterior Stemi, Saddleback, Early Repol? — July 8, 2016 -
• Convex ST Elevation not due to STEMI — July 14, 2016 -
• WCT in a 12-Year Old — July 20, 2016 -
• ST Elevation in V1,V2 — RV MI, Brugada or Hyper-K ? — July 24, 2016 -
• Bifascicular vs Trifascular Block / Acute Changes? — July 30, 2016 -
• Proportionality of ST-T and the QRS (Ant. STEMI ) — August 5, 2016 -
• Is this Brugada-1 or a Saddleback? (syncope) — August 10, 2016 -
• Bidirectional VT vs AVNRT with Alternating RBBB? — August 25, 2016 -
• RVH vs RBBB vs Both? — Acute PE? (large RV on Echo) — Sept. 1, 2016 -
• Subtle LCx Occlusion or Not? — Sept. 4, 2016 -
• LAD Occlusion vs Early Repol (interpolated PVC) — Oct. 18, 2016 -
• Right Precordial T Wave Inversion (benign) — Dec. 5, 2016 -
• Changing ST Elevation Distribution (Spasm) — Dec. 7, 2016 -
• Computer Reads "Non-specific" Abnormalities — Dec. 10, 2016 -
• Cabrera Format at 50mm/sec (a patient with chest pain) — Dec. 29, 2016 -
• LVH with Marked ST Depression + Chest Pain — Jan. 6, 2017 - 
• Wide Tachycardia with Cyanosis (VT vs SVT ...) — Jan. 10, 2017 -
• LBBB, Chest Pain and Evolving ST-T Changes — Jan. 20, 2017 -
• A Fast SVT in a Child (rate ~220/minute) — Jan. 22, 2017 -
• Cocaine Overdose and Brugada ECG Pattern — Jan 25, 2017 - 
• Group Beating & Hyperkalemia (Brugada Phenocopy) — Jan. 27, 2017 -
• Use of the ECG with Severe DKA (U waves) — Feb. 2, 2017 -
• Inferior MI, LVH or Both? (a patient with chest pain) — Feb. 5, 2017 -
• ST Elevation, Neg Troponin but NOT Early Repol! — Feb. 10, 2017 -
• Subtle Use of Smith-Sgarbossa Criteria with LBBB — Feb. 20, 2017 -
• Unstable WCT not responding well to Cardioversion — Feb. 23, 2017 -
• 40yo Man with Chest Pain and "Funny" ST-T Waves — March 1, 2017 -
• Another 40yo Man with Chest Pain (recurring "theme" ) — March 3, 2017 -
• Impending LAD Occlusion (recognizing subtle Wellens) — March 9, 2017 -
• Do Computerized Interpretations Miss Acute STEMIs? — March 10, 2017 -
•   — Related Post: EMS 12-Lead (on Triaging ED ECGs) — March 11, 2017 -
• VT vs SVT with Aberration in a 20yo with DKA - March 17, 2017 -
• T Peaking and "Pseudo-Infarction" with Dehydration - March 19, 2017 -
• Alternating Fascicular Block Aberrancy (and LSFB! ) - March 31, 2017 -
• RBBB with Transient ST Elevation (Rhythm?) - April 2, 2017 -
• Acute or Recent Anterior MI vs LV Aneurysm? - April 21, 2017 -
• 16yo Girl with Overdose: LBBB vs WPW? - April 23, 2017 -
• 40yo Woman with Chest Pain (KEY subtle findings! ) - April 27, 2017 -
• LVH Pseudo-Infarction Pattern vs Wellens? - May 3, 2017 - 
• ST Elevation in V1,V2 in a Patient with LVH - May 6, 2017 -
• TQRSD (Terminal QRS Distortion) - May 13, 2017 - 
• Dialysis Patient with Bradycardia ... - May 18, 2017 -
• Acute STEMI in a post-Op Paced Tracing - May 19, 2017 -
• "Busy at Triage" (subtle-but-real LCx signs ... ) - May 26, 2017 -
• Chest Pain, GE Reflux and Subtle ST-T Wave Changes - May 29, 2017 -
• ST Elevation with Reciprocal Change due to ? (MI vs K+?) - June 1, 2017 - 
• Peaked T Waves in 35yo with DKA/Something Else? - June 17, 2017 -
• Peaked T waves in a 20yo. Anything Else? - June 21, 2017 - 
• Pulmonary Edema on Echo + Interesting ECG LVH - July 7, 2017 -
• Subtle ECG Changes in an 82yo with Syncope - July 12, 2017 -
• The Computer says, "AFib". Do you agree? - August 11, 2017 - 
• Effect of Adenosine on this Rhythm? (AFlutter? ) - August 23, 2017 -
• To Thrombolyse after 15 Hrs of Chest Pain? - Sept. 1, 2017 -
• DeWinter T Waves / AIVR - Sept. 24, 2017 - 
• A 30yo Woman with Chest Pain. Is her ECG Normal? - Sept 30, 2017 -
• VT or Supraventricular with LBBB? - Oct. 14, 2017 -
• Syncope in an Elderly Man ( ? Wellens ? ) - Oct. 25, 2017 -
• Chest Pain but a Non-Diagnostic ECG ... - Nov. 1, 2017 -
• How to Convince the Cardiologist ??? - Nov. 6, 2017 -  
• Chest Pain & a "Normal ECG" by Computer Report - Nov. 10, 2017 - 
• 50yo with Chest Pain (Concept of "Competing Conditions") - Nov 15, 2017 - 
• 30yo with Chest Pain and this ECG (S1Q3T3; IRBBB,ST) - Nov. 22, 2017 - 
• About the QTc Interval (Using the Rule of Thumb for QTc) - Nov. 24, 2017 - 
• RBBB, Missed Occlusion on ECG, What is the Rhythm? - Nov 25, 2017 - 
• Subtle Abnormality in a 54yo with Chest Pain - Nov. 27, 2017 - 
• Post Cardiac Arrest ECG (Acute MI vs something else?) - Nov. 30, 2017 -   
• Why the Inf. ST Depression? What's the Rhythm? - Dec. 1, 2017 - 
• 30yo with Pulmonary Hypertension and this ECG - Dec. 13, 2017 -
• A Challenging Wide Rhythm (Syncopal patient) - Dec. 16, 2017 -
• Wellens' ST-T Waves or Something Else? - Dec. 18, 2017 -
• Serial Tracings tell the Tale (Cancellation Effect) - Dec. 23, 2017 -
• Not a "STEMI", but NOT Normal! (Ed Burns, LITFL) - Dec. 27, 2017 -
• Subtle Findings in a Patient with Chest Pain - Dec. 29, 2017 -
• There is nothing subtle about this ... Right? - Jan. 2, 2018 - 
• Acute MI or Something Else? - Jan. 5, 2018 -
• ST Elevation: STEMI vs Early Repol vs Pericarditis? - Jan. 8, 2018 -
• Use of Terminal QRS Distortion (acute stemi- AIVR) - Jan. 11, 2018 -
• Chest Pain and ST Elevation (old inf MI? Pericarditis?) - Jan. 17, 2018 -
• Repolarization Variant? LVH? and/or Acute STEMI? - Jan. 24, 2018 -
• STEMI? Need for Acute Cath? — or Not? - Jan. 26, 2018 - 
• The Importance of Comparison Tracings (subtle! ) - Jan. 28, 2018 -
• Artifact in a Dialysis Patient (Not hyperacute ST-T ! ) - Jan. 30, 2018 -
• Subtle Changes in a Patient with CP (but no doubts! ) - Feb. 1, 2018 - 
• Acute LCx Occlusion despite Non-Diagnostic ECG! — Feb. 5, 2018 -
• Cardiac Trauma — Now ST Elevation (on Pericarditis) — Feb. 7, 2018 -
• LBBB + CP — Is there Acute Coronary Occlusion? - Feb. 11, 2018 - 
• Subtle Abnormality (in leads III,T inversion in aVL) - Feb. 15, 2018 -
• What's the Temperature? (from an unresponsive woman) - Feb. 19, 2018 -
• Hyperacute ST-T Waves in an evolving STEMI - Feb. 22, 2018 -
• RBBB with Subtle Ischemic Changes ... - Feb. 24, 2018 -
• Diffuse ST Depression + ST Elevation in aVR - Feb. 28, 2018 -
• Anterior ST Elevation: To Activate or Not? - March 5, 2018 -
• Alcohol Withdrawal + a very Long QTc - March 8, 2018 -
• Seizure + a somewhat long QTc Interval - March 9, 2018 - 
• A Pattern To Recognize! ( = Acute PE! ) - March 12, 2018 -
• LBBB Criteria Redefined? Acute STEMI? - March 14, 2018 -
• Not Wellens, but V1,V2 Too High on Chest - March 16, 2018 -
• STEMI vs Pericarditis/Early Repol - May 14, 2011/March 18, 2018 -
• SVT & Retrograde Atrial Activity (AVNRT vs AVRT?) - March 20, 2018 -
• You had 2 Hours to Save this Patient (missed STEMI ) - March 24, 2018 -
• A Tale of 2 STEMIs- Step-by-Step (computer report) - March 27, 2018 -
• NOT an OMI despite HUGE Anterior S Waves! (Superb! ) - April 4, 2018 -
• Regular Wide Tachycardia due to HyperKalemia! - April 6, 2018 - 
• ST Elevation + Hyperthyroidism + LVH + Repol - April 9, 2018 - 
• U Wave Inversion — Clinical Significance ... - April 14, 2018 -
• RBBB with HyperKalemia — Anything Else? - April 16, 2018 -
• Pseudonormalization of ST-T wave and QRS changes - April 20, 2018 -
• Subtle Hyperkalemia on Serial ECG Findings ... - April 22, 2018 -
• Isolated ST Elevation in aVL (cardiac spasm) - April 23, 2018 -
• Cardiac Arrest / "Shark Fin" ST Elevation (Me on ETT ) - April 25, 2018 -
• Abnormal T (U) Waves in an Alcoholic - May 4, 2018 -
• Fascicular VT vs Bundle Branch Reentrant VT - May 8, 2018 -
• AV Dissociation in a Young Man (AV block? ) - May 11, 2018 -
• Isolated Posterior STEMI (Mirror Test - LCx) - May 19, 2018 -
• Cardiac Arrest and an Abnormal 12-Lead (RVH/LVH) - May 24, 2018 -
• Acute Posterior MI despite RBBB (posterior leads Not) - May 26, 2018 -
• LIST: A Long QT/QU + U Waves (Drugs/Lytes/CNS) - May 27, 2018 -
• Paced ECG + Primary ST-T Wave Changes! (Acute MI) - May 29, 2018 - 
• Repost of this 2015 WCT Rhythm: Is the QRS Wide??? - May 30, 2018 -
• LBBB with LA-LL Lead Reversal + Suble ST Changes - June 4, 2018 -
• Bradycardia, Wide QRS, Pointed T, Hypotension (artifact) - June 6, 2018 - 
• Is the QRS really so Wide? (shark fin) - June 11, 2018 - 
• Inf. STEMI vs Constrictive Pericarditis (Schamroth sign) - June 17, 2018 -
• WPW or AIVR? Why AIVR? ( = Sinus Brady ...) - June 18, 2018 -
• What is Terminal QRS Distortion (Pericarditis @ Peril) - June 20, 2018 -
• LBBB, modified Sgarbossa, Qualitative ST-T Changes - June 22, 2018 -
• Does this ECG help Manage Insulin Overdose? (low K+) - June 24, 2018 -
• Early Repol vs OMI vs Pericarditis (AFib/Group Beating) - June 26, 2018 -
• Wellens' Syndrome + Change in Serial Tracings! - June 28, 2018 -
• Type 1 MI with a Normal Cath (isolated high lateral MI) - July 1, 2018 - 
• Use of Terminal QRS Distortion to make the Diagnosis! - July 3, 2018 -
• Slower-than-Expected AFib + Syncope (about SSS!) - July 5, 2018 -
• When Should the OMI Dx have Been Made? - July 8, 2018 -
• Acute Inf. OMI + RV MI (Hyperacute ST-T / Mirror-Image) - July 11, 2018 -
•    — Also — ischemia-induced J waves (My July 11 Comment)
• Acute High Lat. OMI (only seen in aVL) - July 13, 2018 -
• Recognizing LQTS (Long QT Syndrome) on ECG - July 17, 2018 -
• Sodium-Channel Blockade on ECG (Long QTc) - July 20, 2018 -
• ECG Findings of Hypokalemia — and — Anything Else? - July 22, 2018 -
• ECG Findings of Hyperkalemia (Eiffel Tower/Rhabdo) - July 24, 2018 -
• Is there ST Elevation? (Acute PE/Simultaneous Leads) - July 26, 2018 -
• Paramedic recognition of subtle OMI (V1,2 malposition) - July 28, 2018 - 
• Limb Lead and Chest Lead Misplacement (Recognition!) - July 29, 2018 -
• CP in 30yo Woman (Subtle Abns in 11/12 leads/Compare) - July 31, 2018 -
• A Regular SVT — How to Diagnose AFlutter? - August 3, 2018 -
• A Regular WCT with an LBBB-like Pattern ... - August 5, 2018 -
• A 13yo with SOB (WPW - arrhythmias - localization) - August 7, 2018 -
• Lots of ST Elevation: Repol vs STEMI? ("mirror-image") - August 9, 2018 -
• Acute LMain Occlusion! — and a subtle initial tracing ... - August 30, 2018 -
• 2 Occlusions (Good and less good ECG interpretation ... ) - Sept. 2, 2018 -
• Reverse Takotsubo and an Unusual ECG - Sept. 4, 2018 -
• Subtle Post-Lat OMI (LCx) + VT with AV Diss/Capture - Sept. 7, 2018 -
• 50yo Woman with CP & "Normal" Triage Tracings - Sept. 11, 2018 -
• Acute PE (ECG & Echo findings) - Sept. 12, 2018 -
• Idiopathic VT — Fascicular VT (See My Comment) - Sept. 14, 2018 -
• Subtle Serial ECG Changes in a 30yo with CP - Sept. 15, 2018 -
• Hyperacute T Waves (The Wrong Question was Asked) - Sept. 20, 2018 -
• AFlutter with subtle Anterior STEMI (Use calipers! ) - Sept. 24, 2018 -
• Cabrera Format - 50mm/second speed - Chest Pain ... - Sept. 26, 2018 -
• Dialysis Patient — "Pseudonormalization" ST-T Waves - Sept. 29, 2018 - 
• Giant T Waves / Origin of an Atrial Rhythm - October 1, 2018 -  
• Paced ECG with Acute Anterior STEMI (Sgarbossa) - October 3, 2018 -  
• Subtle Acute High-Lat STEMI (aVL-mirror image) - October 6, 2018 -  
• Acute STEMI diagnosed ONLY by PVC Morphology - October 8, 2018 -  
• Another Invalid Study on Triage ECGs in the ED - October 9, 2018 -  
• Subtle OMI in a Triage ECG (PR vs TP Baseline) - October 14, 2018 - 
• Anterior MI + PVCs (Subtle rhythm-junctional escape) - Oct. 19, 2018 - 
• 80yo man with sudden PEA (no clear "culprit" on ECG) - Oct. 22, 2018 -
• Normal Troponin & Acute Occlusion (ischemic J waves) - Oct. 24, 2018 - 
• Inf. ST Elev but No MI! (ST straightened- a "normal" ST) - Oct. 27, 2018 - 
• Diffuse ST Dep/ST Elev in aVR (Recognize this pattern! ) - Oct. 31, 2018 - 
• Q waves in V1,V2 = Septal MI? (or V1/V2 Misplacement?) - Nov. 4, 2018 -
• Recognition of a Long QTc (Assessing the QTc- LIST ) - Nov. 7, 2018 - 
• A Case-Based Study of Pacer Malfunction (bradycardia) - Nov. 9, 2018 - 
• 2 ECGs Texted to Dr. Meyers (Acute STEMI or not?) - Nov. 12, 2018 - 
• Serial ECG Changes over 10 tracings in Acute STEMI - Nov. 15, 2018 - 
• Hyperacute T waves - new LAHB + Inf. Q waves = OMI - Nov. 18, 2018 -
• RBBB + Chest Pain: New vs Old? - Nov. 21, 2018 - 
• Acute STEMI missed by the Computer - Nov. 21, 2018 -
• Are these Hyperacute T waves? (Computer says stemi) - Nov. 24, 2018 - 
• Regular SVT at 200/min. + acute STEMI? (Semantics) - Nov. 26, 2018 - 
• ST Elev. in V1,V2 — STEMI? Brugada-2? (or leads?) - Nov. 28, 2018 - 
• Shock, LVH and/or Diffuse Subendocardial Ischemia - Nov. 30, 2018 -
• 2 ECGs without a History: Acute Changes or Not? - Dec. 5, 2018 - 
• Not Bigeminy — But a Problem with K+ & Ca++ (DKA) - Dec. 11, 2018 - 
• Can this be Wellens' Syndrome without an Infarct? - Dec. 14, 2018 -
• A Regular WCT: VT vs AFlutter + Flecainide Toxicity? - Dec. 16, 2018 - 
• The Computer Called this Normal (Subtle STEMI ) - Dec. 19, 2018 - 
• Subtle ST-T wave changes (Normal vs Flat ST segment) - Dec. 24, 2018 - 
• ST Elevation in V1-3: Ant MI vs Strain (ECG Dx of LVH) - Dec. 27, 2018 - 
• ST Elevation in V3: Is it Normal? (More on ECG Dx LVH) - Dec. 29, 2018 - 
• Benign T Wave? Hypertrophic CardioMyopathy? - Jan. 2, 2019 - 
• "Who Done It? = HyperKalemia + HypoCalcemia - Jan. 3, 2019 - Jan 7 -
• Dynamic ST-T Wave Changes (Myocarditis, LVH) - Jan. 9, 2019 -
• Isolated RV MI + unusual pointed ischemic T waves - Jan. 11, 2019 -
• Bradycardia & AV Block from Hyper-K (Rhythm Pearls) - Jan. 13, 2019 - 
• The Regular WCT: VT vs SVT with Aberrancy? - Jan 24, 2019 - 
• Junctional vs Low Atrial Rhythm? (neg P  or part QRS?) - Jan. 28, 2019 - 
• Hyperthermia and ST Elevation in V1,V2 (Brugada-1) - Jan. 30, 2019 - 
• Diffuse ST Dep/ST Elev in aVR not due to CAD (low K+) - Feb. 2, 2019 - 
• Subtle OMI diagnosis by ECG Comparison (pos Trop) - Feb. 5, 2019 - 
• Right-Sided HF and an SVT (Why is this AFlutter?) - Feb. 9, 2019 -
• RVH - IRBBB: Is Ant T Inversion New or Old? - Feb. 12, 2019 - 
• How Long Will You Wait for OMI to become STEMI? - Feb. 16, 2019 - 
• Coved ST Elevation in Chest Leads: Acute or Not? - Feb. 18, 2019 -
• Cardiac Arrest, ROSC and now RBBB? (very wide! ) - Feb. 28, 2019 - 
• LVH, diffuse ST dep/ST elev in aVR (Sickle Cell ) - March 2, 2019 - 
• Monitor Leads for ST Elevation? (Filter Settings! ) - March 4, 2019 -
• Recognizing abnormal ST elevation in V1,V2 - March 6, 2019 - 
• Subtle Acute MI (Is complex A or B in aVL correct?) - March 8, 2019 - 
• Resp. Failure + a "Normal" Computer ECG ("smiley" ) - March 11, 2019 - 
• What is the Rhythm? (2 Regular WCTs vs 1 Rhythm?) - March 13, 2019 - 
• The SHAPE in lead V2 — Acute OMI - March 15, 2019 - 
• Acute OMI Dx'd by Speckle Echo (an unusual IVCD) - March 18, 2019 - 
• Electrolytes — Pathognomonic ECG (hypoCa/hyperK) - March 19, 2019 - 
• Junctional Escape (Laddergram)/SubEndo Ischemia - March 26, 2019 -
• Subtle High-Lat OMI + 3 False Pos (ST elev in aVL) - March 29, 2019 -  
• 3 ECG shown to Dr. Meyers (To Activate Cath Lab? ) - March 31, 2019 - 
• Acute LAD Occlusion in an Elderly Patient - April 3, 2019 - 
• ECG Findings & Clinical Diagnosis of Acute PE - April 5, 2019 - 
• A Pt with Abdominal Pain and LBBB (qualitatively + ) - April 7, 2019 -
• Acute OMI missed because it wasn't a "STEMI" - April 12, 2019 - 
• Type 2 MI + Myocardial Bridging + Tachy/ST Elev - April 15, 2019 - 
• Acute Pericarditis or a Repolarization Variant ECG? - April 19, 2019 -
• OMI despite no STEMI ( + V2 lead malposition) - April 20, 2019 - 
• CP & ST Depression only in leads I and aVL ... - April 22, 2019 -
• A WCT Rhythm with Alternating Wide-Narrow Beats - April 23, 2019 - 
• Dx of Acute STEMI despite being a Paced Tracing - April 25, 2019 - 
• Terminal QRS Distortion (T-QRS-D) - LVH Voltage - April 27, 2019 - 
• LBBB vs WPW (LBBB criteria- All about WPW) - April 30, 2019 - 
• Tachyarrhythmias: Use of Monitor vs a 12-Lead ECG - May 1, 2019 -
• De Winter T Waves (Typical & Atypical Features) - May 2, 2019 - 
• Brugada ECG Patterns vs Acute Anterior STEMI - May 6, 2019 - 
• Don't Overlook this OMI (Be Systematic/Computer Use) - May 7, 2019 -
• Another Anterior OMI/Not Repol (the Visual Picture) - May 11, 2019 - 
• Chest Pain in a Pt with a Paced Rhythm (2:1 ATach?) - May 13, 2019 - 
• Peaked T Waves despite serum K+ = 2.4 mEq/L - May 15, 2019 -
• LVH and/or Acute OMI (Nit-Picking Serial Tracings/LVH) - May 19, 2019 - 
• LBBB: Recognizing Acute OMI (Smith-Mod-Sgarbossa) - May 24, 2019 - 
• Acute Ant. OMI (What will Cardiologist do Next Time?) - May 26, 2019 - 
• A Complex ECG and No Clinical Info (Laddergram) - May 28, 2019 - 
• Superimposed Changes on Prior Antero-Lat STEMI? - June 2, 2019 - 
• Cardiologist & Computer said "Normal" (acute OMI) - June 4, 2019 -  
• Is ST-T wave SHAPE normal? (Cath lab activation? ) - June 7, 2019 -
• How Not to Miss WPW (Reviews My Approach) - June 8, 2019 - 
• Hyperacute T Waves (on way down) - Computer - June 9, 2019 - 
• 20yo with Chest Pain: Early Repol or Something Else?- June 11, 2019 - 
• A Patient with SOB (Systematic-LVH-QTc-hyper-K+) - June 15, 2019 - 
• Dr. Smith's 3- and 4-Variable Formula (Ant STEMI? ) - June 17, 2019 - 
• Repolarization Variants vs LVH-HCM-STEMI? (blacks) - June 20, 2019 - 
• "Smiley"-shape ST Elevation (Using this Concept! ) - June 22, 2019 - 
• Very Subtle Inferior Lead ST-T Wave Change - June 23, 2019 -
• Quick Recognition of Acute Proximal LAD Occlusion - June 26, 2019 -
• A System needed to pick up all Findings! (Inf OMI ) - June 28, 2019 - 
• 2 Cases of RBBB (My Approach for ECG Dx of BBB) - July 1, 2019 - 
• CP Onset 24-48 Hrs Ago (2 Post MIs- Correlate to Hx) - July 5, 2019 - 
• Subtle-but-definite acute LAD OMI (artifact! ) - July 11, 2019 - 
• ST Elevation only in V6/Recip in V1 (LCx-Post MI ) - July 15, 2019 - 
• Doubling Size of Complexes Facilitates OMI Dx! - July 17, 2019 - 
• Subtle LAD OMI: New vs Old? (Brugada-like) - July 19, 2019 - 
• Acute Myocarditis vs OMI vs Repol (Serial Tracings) - July 21, 2019 - 
• The ECG was Correct; the Angiogram was Not! - August 13, 2019 - 
• 5 Cardiologists say No STEMI — Is in an OMI? - August 15, 2019 - 
• CP in a 50yo with a "Normal" ECG — Or an OMI? - August 18, 2019 - 
• Evidence of Acute OMI on this Pacer Tracing? - August 20, 2019 - 
• Are these Hyperacute T Waves? - August 26, 2019 - 
• Short QTc Syndrome vs Hyperkalemic T Waves - Sept. 2, 2019 - 
• Recognize this ECG? (HyperK- Brugada Phenocopy) - Sept. 8, 2019 - 
• Non-Cardiac Ischemia on ECG (+ a few questions) - Sept. 12, 2019 - 
• Troponin Trajectory: New Ant MI vs LV Aneurysm? - Sept. 17, 2019 - 
• When the QRS is Wide — the J-Point will Hide! (VSD) - Sept. 20, 2019 - 
• Why do beats "A" and "B" look so different? (artifact) - Sept. 22, 2019 - 
• 7 mm of ST Elevation with LBBB = Acute? What Else? - Sept. 25, 2019 - 
• Acute MI diagnosis by Chest CT (+ suble ECG/Artifact) - Sept. 27, 2019 - 
• Subtle Inf. OMI / MAT at normal Rate - Sept. 30, 2019 - 
• ST Depression in a 30yo (Atrial Repol Wave/Tachycardia) - Oct. 2, 2019 - 
• Shark Fin Morphology (Don't Forget to look for P waves! ) - Oct. 4, 2019 - 
• Interplay between Post MI and acute RV MI! - Oct. 9, 2019 - 
• Do You Understand these T Wave Inversions? - Oct. 10, 2019 - 
• Regular SVT (AVRT — 30yo with WPW — Mgmt) - Oct. 16, 2019 - 
• Acute Inf-Lat OMI (QS inf leads-Tall R V1-Silent MI ) - Oct. 20, 2019 - 
• Causes of ST Depression ("scooped" ST/Dig/LIST ) - Oct. 21, 2019 - 
• SCAD (Spontaneous Coronary Artery Dissection) - 30f - Oct. 24, 2019 - 
• Look at All ECGs done Serially! (Subtle clues! ) - Nov. 1, 2019 - 
• Diffuse Subendocardial Ischemia (not always cardiac! ) - Nov. 3, 2019 - 
• Vagotonic AFib in 30yo (The RATE of AFib - D.D.) - Nov 5, 2019 - 
• Subtle Changes = an ECG non-diagnostic of OMI (Lytics?) - Nov. 8, 2019 - 
• What is this SVT @ 150/min? (AFlutter — MY POST ) - Nov. 12, 2019 -
• Repolarization Variants vs Acute OMI (T-QRS-D) - Nov. 14, 2019 - 
• Seizures — Review of HypoKalemia - Nov. 18, 2019 - 
• CP in a 30yo — Acute OMI? (Serial ECGs) - Nov. 20, 2019 -
• Cardiac Arrest — Shark Fin/ Osborn Waves/ Low Atrial - Nov. 22, 2019 -  
• Is there Global ST Depression? — or Atrial Flutter? - Nov. 26, 2019 - 
• Acute Pancreatitis/LVH and Repol vs Acute OMI? - Nov. 27, 2019 - 
• Distinguishing New vs Old MI (vs superimposed MI) - Nov. 29, 2019 - 
• A 30yo woman with Fever-Induced Brugada-1? - Dec. 5, 2019 - 
• CO Poisoning — Prox LAD Occlusion (T-QRS-D ) - Dec. 9, 2019 - 
• Acute Myocarditis vs Repol vs OMI (Serial ECGs) - Dec. 10, 2019 - 
• Acute PERICARDITIS (detailed discussion! ) - Dec. 13, 2019 - 
• Acute OMI despite LBBB (Smith-Sgarbossa- subtle! ) - Dec. 16, 2019 - 
• More on HypoKalemia - Dec. 18, 2019 - 
• A Regular WCT (Wide-Complex Tachycardia) - Dec. 23, 2019 - 
• Don't Overlook AFlutter! (Regular SVT at ~150/minute) - Dec. 24, 2019 - 
• Mobitz II in an Asymptomatic 80yo (AV Blocks) - January 1, 2020 -  
• Hypothermia with Osborn Waves! - Jan. 2, 2020 - 
• MAT - the Computer - Aberrant Conduction (Ashman) - Jan. 5, 2020 - 
• Crochetage Sign — Is there an ASD? - Jan. 8, 2020 - 
• Acute Pericarditis (Myocarditis)? Acute OMI? Repol? - Jan. 10, 2020 - 
• Acute MI + Post-Infarction Pericarditis (Review) - Jan. 14, 2020 - 
• Acute LMain Occlusion (ECG Recognition) - Jan. 16, 2020 - 
• Acute Inf OMI (Complex Rhythms-Ladder-Mobitz I ) - Jan 19, 2020 - 
• RBBB + 1° ST-T changes/AFib + AV Block (SSS? ) - Jan 22, 2020 - 
• "Shark Fin" / Myocardial "Stunning" ==> Low Voltage - Jan. 24, 2020 - 
• Hyperkalemia (Ventricular Escape - ECG Changes) - Jan. 26, 2020 - 
• 20-ish yo with Chest Pain (distal LAD OMI - subtle) - Jan. 29, 2020 - 
• Hx of Stents with Chest Pain (RBBB-Fragmentation) - Jan. 31, 2020 - 
• 7 Tracings: Which 3 have Acute Inferior OMI? - Feb. 2, 2020 - 
• Cardiology would Not Cath this Patient! (Ant. OMI ) - Feb 4, 2020 -
• ST Elevation in V1,V2 — due to LVH (not ACS) - Feb. 6, 2020 -
• ST Elevation in aVR (Coronary Occlusion?/SVT? ) - Feb XXX, 2020 - - -
• Ischemia vs Lead Misplacement (How to Recognize) - Feb. 11, 2020 - 
• A 50s Man with "Gas Pain" (Early LAD Occlusion) - Feb. 14, 2020 -
• HypoThermia — Shark Fin (Causes of Myocarditis) - Feb. 16, 2020 -
• 32yo with CP — Hyperacute T waves MISSED - Feb. 18, 2020 - 
• What are these Wide Complexes (AV Diss- AIVR) - Feb. 20, 2020 - 
• A Man in his 60s with CP (Subtle OMI) - March 2, 2020 -
• Anterior T Inversion (Not Wellens- PE vs Ischemia) - Feb. 28, 2020 - 
• Sinus Tach with a VERY Long PR Interval - March 4, 2020 -
• ATach vs AVNRT of the Fast-Slow Type - March 6, 2020 -
• ST Elevation in aVR/Diffuse ST Dep (normal cath) - March 9, 2020 -
• A Scenario to Recognize (Irregular WCT-AFib/WPW) - March 12, 2020 - 
• Cardiac Arrest/ECMO — Shark Fin (rhythm) - March XXX, 2020 - - - 
• Differential Diagnosis of a Regular WCT - March XXX, 2020 - - -
• 
  
•  

-------------------------------------------

ECG Interpretation Review #142 (Ischemia - MI - Posterior - Dating Infarction - Chest Pain).

The ECG in Figure-1 was obtained from a 48-year old man who presented to the ED (Emergency Department) with a 3-day history of chest discomfort. It shows evidence of a MI (Myocardial Infarction).

• How would you “date” this MI?
• Which areas of the heart are involved?

Figure-1: 12-lead ECG obtained from a 48-year old man with 3 days of chest discomfort.

-----------------------------------------------------------

Interpretation: The rhythm is fairly regular at 85-90/minute. Upright sinus P waves are seen in lead II. The PR, QRS, and QT intervals are normal. The axis is leftward, but not by enough to qualify as LAHB (ie, the net QRS deflection in lead II is not predominantly negative). There is no chamber enlargement.

---------------------------------

• Terminology Definitions: Before assessing for Q-R-S-T Changes in Figure-1 — it may be helpful to review terminology (See ECG Blog #94). We favor use of the lower case designation “q” wave when the initial negative deflection of a QRS complex is relatively smaller (ie, <3mm in depth). If the initial negative deflection of the QRS complex is larger (ie, ≥3mm in depth) — we favor the upper case designation “Q” wave. When the QRS deflection is entirely negative — the designation “QS” complex is used, since without any upright deflection in the QRS, one can’t tell if the all-negative deflection occurs “before” or “after” the R wave.

---------------------------------

Returning to Figure-1: Regarding Q-R-S-T Changes ...

• Q waves are present in multiple leads. Small, narrow (probably septal) q waves are seen in leads I and aVL. The Q wave in lead II is narrow but deep (ie, it is virtually as deep as the height of the R wave in this lead). Of note, there may be a tiny initial positive deflection (r wave) in at least some of the beats in lead III. However, in lead aVF — the QRS complex is clearly all negative, which defines this as a QS complex. There is also a distinct notching (called fragmentation) on the upslope of this QS complex in lead aVF. Finally, there are Q waves in leads V4, V5, and V6. Although narrow, the Q waves in leads V5, V6 are somewhat deeper-than-expected to be simple “septal” q waves.

---------------------------------

• Clinical Note on Q Wave Significance: In general, the larger and wider a Q wave is — the more likely this Q wave is to be “significant” (ie, indicative of infarction at some point in the patient’s history). That said, numerous exceptions exist — such that reliable generalizations about the clinical significance of Q wave appearance are difficult to make. It is common to see small narrow q waves in one or more of the lateral leads. These “normal septal q waves” reflect the normal direction of septal activation, which moves from left-to-right. That said, distinction between normal septal q waves and Q waves indicative of previous lateral infarction may be challenging when q wave width and/or depth appears to be more-than-expected, as is seen here for the 3mm deep Q waves in leads V5 and V6. On the other hand, we can definitely say that QRS appearance in the 3 inferior leads (leads II, III, aVF) in Figure-1 IS strongly suggestive of prior infarction. In the context of a surprisingly deep Q wave in lead II and, an all-negative QS complex with notching (fragmentation) in lead aVF — even if a tiny initial positive deflection is present in some of the beats in lead III, the most likely explanation for this combination of findings has to be prior inferior infarction.

---------------------------------

Returning to Figure-1:

• R Wave Progression — is not normal in the chest leads. Normally, there should be a predominant negative deflection (S wave) in lead V1 — with the area of “transition” (where R wave amplitude supersedes S wave depth) not occurring until after V2,V3. Instead, R wave amplitude in lead V1 = S wave depth in this lead, and relatively prominent R waves are already seen by lead V2. Although there are a number of entities that may produce a Tall R Wave in Lead V1 (See ECG Blog #81) — recent posterior infarction should be at the top of this list, considering the ECG evidence of previous inferior infarction we have just discussed, and the ST-T wave changes we are about to assess.
• ST-T Waves — There is ST segment coving, with fairly deep T wave inversion in each of the inferior leads. In addition, there is 1-2mm of ST depression in leads V3-thru-V6, with a definite ST segment “shelf” in these leads. This strongly suggests ischemia. A final, admittedly subtle finding — is ST segment straightening with angulation of the junction between the straight ST segment and the beginning of the T waves in leads I and aVL. This makes these T waves (especially in lead aVL) appear more prominent than one might normally expect, given R wave amplitude in this lead.

---------------------------------

• Dating an Infarct: A picture “tells 1,000 words”. Rather than QRST appearance in one or two leads — it is the composite picture of the entire 12-lead tracing, in context with the clinical history that “tells a story”. That said, it is good to appreciate that our ability to “date” an infarct from assessment of a single 12-lead ECG is far from perfect. Practically speaking, we are limited to classifying ECG signs of MI as being: i) Acute ( = onset within the past few hours); ii) Old (occurrence more than several days ago); or iii) of Uncertain Age (ie, likely onset being intermediate between “acute” and “old” ) — which includes MIs that may be fairly recent, or of completely uncertain duration.

---------------------------------

Impression: The overall ECG picture that we see in Figure-1 is strongly suggestive of infero-postero (and possible lateral) infarction of uncertain age. In view of the history (ie, that chest pain began 3 days earlier) — there is an excellent chance that onset of the event corresponds to the onset of symptoms that began several days earlier.

• Against calling this infarction “acute” (ie, onset within the past few hours) — is the lack of ST elevation in Figure-1, and the presence already of large inferior Q waves. Yet persistence of ST coving with deep T wave inversion in these inferior leads — in conjunction with ST segment flattening and depression in many of the remaining leads strongly suggests that the event may indeed be recent. Careful questioning of this patient regarding the precise onset and nature of his symptoms over the past week is likely to be revealing.
• PEARL: With acute and/or relatively recent inferior infarction — there is almost always a reciprocal relationship in ST-T wave appearance between leads III and aVL. This is because electrical activity assessed by these 2 leads is almost completely opposite (lead aVL at -30 degrees; lead III lying 150 degrees away at +120 degrees in the frontal plane). Awareness of this relationship often provides an invaluable clue as to whether subtle ST elevation in inferior leads is likely to indicate an acute or recent event. Early repolarization should not produce reciprocal ST depression in lead aVL. Although subtle — there is a reciprocal ( = “mirror” image) relationship in this tracing between the ST coving with deep T wave inversion that is seen in lead III — and the subtle ST segment straightening with somewhat prominent T wave appearance in lead aVL.
• ST-T wave changes of “reperfusion” typically manifest the appearance seen here — that is, with no more than minimal residual ST segment elevation, and with deep T wave inversion in lead groups that overlie the area of infarction. Since anterior leads (ie, leads V1, V2, V3) provide a mirror-image perspective of posterior events — the prominent T waves we see in leads V2, V3 are most likely to represent recent posterior reperfusion. This is consistent with the presence of a disproportionately tall R wave in lead V1, with prominent R wave forces already evident by V2, V3. These findings all support the presence of recent posterior as well as inferior infarction.
• As suggested earlier, deeper-than-expected Q waves in leads V5, V6 may indicate lateral infarction of uncertain age. It is difficult to know if the lateral chest lead ST depression reflects reciprocal change or ongoing ischemia.
• The “Culprit” Artery: Statistically, we would suspect the RCA (Right Coronary Artery) to be the “culprit” artery of infarction in this case — since the large majority of patients have a right dominant circulation (See ECG Blog #141). That said, given the lack of ST segment elevation at this time, the criterion that compares the relative amount of ST elevation in lead III vs lead II cannot be used. Given the possibility of lateral infarction, and absence of ECG evidence suggesting right ventricular infarction — one cannot rule out the possibility of recent LCx (Left Circumflex) occlusion without cardiac catheterization.

---------------------------------
Case Follow-Up: Cardiac catheterization revealed severe multi-vessel disease, including diffuse involvement of the LAD (Left Anterior Descending) artery, diffuse LCx disease with prior occlusion of obtuse marginal branches that now show collateral filling — and, 100% occlusion with fresh thrombus in the RCA. Thus, the RCA was the “culprit” artery in this patient with preexisting extensive and severe coronary disease.

• BOTTOM LINE: The process of determining the onset of acute infarction is not always straightforward. The answer may not be forthcoming from assessment of a single ECG. Instead, careful integration of the clinical history, interpreted in light of the timing of troponin rise and ECG evolution on serial tracings is often needed. The process may be further complicated when a new event is superimposed on severe preexisting coronary disease. This case illustrates how helpful the history can be — even in a patient with preexisting disease, for deducing the likely onset of the most recent event.

-----------------------------------------------------------

Acknowledgment: My thanks to MG for allowing me to use this tracing and clinical case.
-----------------------------------------------------------

NOTE: The following ECG Blogs review material relevant to this case:

• ECG Blog #94 (regarding Q wave terminology; assessment of QRST Changes).
• ECG Blog #81 (regarding differential diagnosis of a Tall R in Lead V1).
• ECG Blog #80 (regarding distinction between LCx vs RCA culprit; Coronary Circulation; the "Mirror Test" ).
• ECG Blog #141 (regarding assessment of the "culprit" artery).

ECG Blog #141 (Anatomy - Lat - Post - Inf - MI)

The ECG in Figure-1 was obtained from a man in his 50s, who presented with new severe chest pain.

• How would you interpret this­­ tracing?
• What area(s) of the heart are involved?
• What is the likely “culprit” artery?

Figure-1: 12-lead ECG obtained from a man in his 50s with chest pain. What is the likely “culprit” artery? 

-----------------------------------------------------------

Interpretation: The underlying rhythm is sinus at a rate of 75-80/minute. Intervals and axis are normal. There is no chamber enlargement. Regarding Q-R-S-T Changes:

• Narrow but fairly deep Q waves are seen in leads III and aVF. There is also a small and narrow q wave in lead II, and a tiny q wave in lead V6.
• Overall R wave progression across the chest leads is appropriate — although R wave amplitude in lead V2 is a bit taller-than-expected. Small s waves persist through to leads V5, V6.
• There is dramatic ST elevation in each of the inferior leads (leads II,III,aVF) with a “check-mark” appearance that strongly suggests acute injury. As a subtle finding, there appears to be slight ST segment elevation in lead V1. The ST segment in this lead is coved and clearly more prominent than is usually the case.
• There is marked reciprocal ST depression in leads I and aVL. Note how the shape of this ST depression in lead aVL is a precise “mirror-image” picture of the ST elevation in lead III.
• There is at least 4mm of “shelf-like” ST depression in lead V2 — which surprisingly largely resolves by lead V3. There is a hint of J-point depression in leads V3-thru-V6.

Impression: In a patient with new-onset chest pain — the ECG appearance in Figure-1 is virtually diagnostic of a large acute infero-postero STEMI (ST Elevation Myocardial Infarction). In addition, there is almost certainly acute RV (Right Ventricular) involvement. This strongly suggests acute RCA (Right Coronary Artery) occlusion. In support of this conclusion — we make the following points:

• Statistically, approximately 80-90% of patients have a “right-dominant” circulation (Figure-2). This means that after supplying the RV (right ventricle) — the RCA continues as the PDA (Posterior Descending Artery) along the undersurface of the heart to supply the posterior and inferior walls of the LV (left ventricle). In contrast, about 15% of patients have a left-dominant circulation, in which the RCA is less prominent. To compensate, the LCx (Left Circumflex) artery is a relatively larger vessel, and it (rather than the RCA) provides most (or all) of the blood supply to the PDA. As a result not only the lateral, but also the inferior and posterior walls of the LV are predominantly supplied by LCx artery in patients with a left-dominant circulation. Bottom Line — Statistically then, even before looking at the ECG, we can predict that the “culprit artery” for the vast majority of patients with acute inferior STEMI is likely to be the RCA (See also ECG Blog #80).

Figure-2: Overview of normal coronary anatomy. Panel A — the most common situation (80-90%), in which the RCA is a dominant vessel that supplies the RV as well as the posterior and inferior walls of the LV. The RCA also provides blood supply to the RV. The LAD (Left Anterior Descending) artery normally supplies the anterior wall of the heart (via diagonal branches); part of the cardiac apex; and a major portion of the conduction system (via septal perforators that run vertically down through the septum). The LCx (Left Circumflex) artery supplies the lateral wall of the LV. Panel B — represents a left-dominant circulation, in which the LCx (rather than the RCA) supplies the posterior and inferior walls of the left ventricle.

-----------------------------------------------------------

ECG features in Figure-1 that further support the likelihood of the RCA as the “culprit artery” are: i) ST elevation in lead III > II; ii) Marked reciprocal ST depression in lead aVL; iii) Relatively less (or no) lateral ST elevation, with the amount of ST elevation in lead III > V6; and, iv) Evidence of acute RV involvement.

• PEARL: The LCx does not supply the right ventricle. Therefore, if there is ECG evidence suggesting acute RV involvement in association with inferior STEMI — this is virtually diagnostic of the RCA being the culprit artery. While ST elevation in right-sided leads (especially in lead V4R) is clearly the best indicator of acute RV MI — lead V1 is a right-sided lead, and on occasion it may provide insight as to whether or not there is likely to be significant associated RV infarction. Normally the ST segment in lead V1 is flat or slightly depressed. With acute inferior STEMI — ST segments in leads V1, V2 and V3 often show ST depression due to accompanying posterior infarction and/or reciprocal changes due to the inferior STEMI. Typically, such ST depression is maximal in lead V2 — but it should also be present in V1. If ever there is ST segment coving (especially if accompanied by some ST elevation) in lead V1 — there is almost certainly acute RV involvement.
• In this case, the marked ST depression in lead V2 (Figure-1) indicates acute posterior involvement. This is supported by the taller-than-expected R wave in lead V2 (positive “mirror test” — See Figure 2 in ECG Blog #80). However, rather than ST depression in lead V1 — there is prominent ST segment coving with suggestion of slight elevation. In the setting of acute inferior STEMI — this is almost certainly the net result of right-sided ST elevation from acute RV infarction attenuating (opposing) the ST depression that should also be seen in lead V1 from acute posterior infarction. And, since the LCx does not provide blood supply to the RV — this finding of ST coving with slight elevation in lead V1, but with marked ST depression by V2 incriminates the RCA as the culprit vessel. It most often indicates proximal RCA occlusion.
• Note that the extent of acute infarction is obviously large in this case — since the amount of ST elevation is profound; ST elevation is accompanied by marked reciprocal ST depression; inferior Q waves have already formed; and inferior, posterior and right ventricular walls are involved.

BOTTOM LINE: Due to the possibility of anatomic variants and/or collateral circulation — definitive identification of the “culprit” artery is only possible with cardiac catheterization. That said, recognition of probable proximal RCA occlusion in this case with associated acute RV involvement is clinically important — because hemodynamics may differ compared to predominant LV infarction (ie, nitroglycerin is not advised because it may excessively lower BP; hypotension in the setting of acute RV involvement responds well to volume infusion).

-----------------------------------------------------------

Acknowledgment: My thanks to MG for allowing me to use this tracing and clinical case.

-----------------------------------------------------------

• See also ECG Blog #80.

ECG Blog #140 – (PVC – Atrial Bigeminy – PAC – LAHB – RBBB – LPHB – Aberration).

The ECG in the Figure-1 was obtained from an otherwise healthy 20-year old man. The patient was asymptomatic. This ECG was obtained when an irregular heartbeat was noted on routine exam.

• How would you interpret this­­ tracing?
• Are these multifocal (multiform) PVCs?
• How certain are you of your answer?

Figure-1: 12-lead ECG obtained from a previously healthy 20-year old man with an irregular heartbeat. Are these multiform PVCs?

-----------------------------------------------------------

Interpretation: The underlying rhythm is sinus. Virtually every-other-beat occurs early and looks different, with at least some degree of QRS widening. That said, these are not PVCs (Premature Ventricular Contractions). Instead, the rhythm is atrial bigeminy, in that every-other-beat is a PAC (Premature Atrial Contraction).

• We know that the different-looking beats here are not PVCs — because: i) these early beats are preceded by premature P waves (RED arrows in lead II of Figure-2); and, ii) QRS morphology of the early beats is highly characteristic for aberrant conduction (See below). 

Distinguishing between early-occurring wide beats that are ventricular in etiology (ie, PVCs) vs PACs that are wide because of aberrant conduction is at times a challenging task! 

• We have previously reviewed this topic in detail in earlier ECG Blog posts (See ECG Blog #14 and Blog #15). This particular case applies principles brought forth from those previous ECG Blog posts that convincingly demonstrates the widened beats in Figure-1 are PACs with aberration.

Figure-2: The ECG from Figure-1 has been labeled (See text for full explanation).

 

Why We KNOW that Aberration is Present in Figure-2:
The most convincing evidence for establishing that aberrant conduction is the etiology of early-occurring widened beats in this tracing lies with recognition of premature P waves. In contrast, PVCs are not preceded by premature P waves. RED arrows in lead II of Figure-2 highlight the presence of a premature P wave with constant PR interval before each early beat (ie, beats #1,3,5,7).

• The fact that deflections highlighted by red arrows in lead II occur at this exact point in virtually all other simultaneously-recorded limb leads establishes that these deflections are real and not artifact.
• Note: It is common to see PR interval prolongation for PACs (as is the case here) — since early-occurring atrial activity is clearly more likely to encounter some delay as it traverses an AV node that may not yet have recovered full conduction properties.

Aberrant Conduction is most likely to take the form of some type of bundle branch block and/or hemiblock pattern. As a result — attention to QRS morphology may sometimes help to distinguish between aberrancy vs ventricular beats.

• By far — the most common form of aberrant conduction manifests a RBBB (Right Bundle Branch Block) pattern. This is because under normal circumstances, the right bundle branch tends to have the longest RP (Refractory Period) — which means, that an early-occurring impulse (ie, a PAC) has the greatest chance to arrive at the AV node at a time when the right bundle branch is still refractory. That said, any form of conduction defect may be seen with aberrant conduction — depending primarily on the relative length of the RP for the various conduction fascicles in a given patient. As a result — there may be LBBB (Left Bundle Branch Block) aberration; aberration of either hemifascicle ( = LAHB or LPHB = Left Anterior HemiBlock or Left Posterior HemiBlock aberration) — or, any combination thereof (ie, RBBB/LAHB or RBBB/LPHB aberration).
• KEY POINT: If early beats manifest highly typical QRS morphology for any one or any combination of conduction defect — this is highly suggestive that the widened beat (or run of beats) is supraventricular with aberrant conduction. The converse, however — is not true! That is, aberrant conduction is still possible even if QRS morphology of early beats does not resemble any form of conduction defect(s). In such cases — other ECG criteria will have to be used for distinguishing between ventricular vs supraventricular etiology. 

Unfortunately, Figure-2 does not provide us with an uninterrupted long-lead rhythm strip. That said, it should be obvious that every-other-beat (ie, each odd-numbered beat) manifests a different and widened QRS morphology.

• Attention to premature beats #9 and 11 in lead V1 reveals a highly characteristic RBBB morphology, especially for beat #9 — which shows initial small, narrow r wave; followed by S wave that descends below the baseline in V1; followed by a terminal tall R’ (ie, taller “right rabbit ear”).
• Note the presence of a terminal wide S wave in simultaneously-occurring beats #9 and #11 in lead V6. In contrast, beat #13 in lead V1 is only minimally different in morphology from normally conducted beats #8,10 and 12. As might be expected, there is no terminal wide S wave for beat #13 in simultaneously-occurring lead V6. ECG recognition of this very highly characteristic RBBB morphology in leads V1 and V6 for early-occurring beats #9 and 11 is virtually diagnostic of RBBB aberration.
• Turning our attention to the limb leads — we know (even without seeing a simultaneously-recorded lead V1) that beats #1, 3, 5 and 7 are also all conducted with a typical RBBB pattern, because each of these beats manifests a terminal wide S wave similar to that we have already intermittently seen in lead V6. What is especially fascinating about this tracing — is that while early beats #1 and 3 only manifest RBBB aberration — beat # 5 manifests RBBB/LPHB aberration — and, beat #7 manifests RBBB/LAHB aberration. We say this, because of the typical very deep straight S wave in lead I of beat #5 that occurs in association with a qR pattern in leads II,III (highly typical of LPHB!) — whereas we see an rS complex with predominant negativity in leads II and III for beat #7 (highly typical of LAHB!).
• And then there is beat #13 — which despite being early, occurs without a RBBB pattern, and with no more than minimal aberration.

BOTTOM LINE: PVCs do not do what we see here. More than the already diagnostic presence of premature P waves preceding each early beat (best seen in the limb leads) — changing QRS morphology of every-other-beat manifesting multiple variations of highly typical conduction defect morphology establishes with 100% certainty that the rhythm in Figures-1,2 is Atrial Bigeminy with varying forms of Aberrant Conduction.

• Otherwise, judging from QRST morphology in the normally conducted beats — there do not appear to be any acute changes on this tracing.

-----------------------------------------------------------

Additional Reading: 

-----------------------------------------------------------

• See also ECG Blog #14 and Blog #15).