Monday, May 2, 2022

ECG Blog #302 (QC) — An ECG Quick Case ...


NOTE (5/2/2021): 
I'm adding a feature to my ECG Blog — namely, some ECG "Quick Cases" ( = EQCs) — in which I'll provide "quick answers" to short ECG cases, with my impression of the "essentials" that come to me within the first few seconds that I see the tracing.
  • While I always encourage a systematic approach to ECG assessment — my goal is to help expedite clinical decision-making.
  • I'll add LINKS at the bottom of each case where more detailed discussion can be found on related cases.

I WELCOME your feedback on this new feature!
Ken Grauer, MD (ekgpress@mac.com)

===========================================

The ECG in Figure-1 was obtained from a patient with chest pain.
  • How would YOU interpret this tracing?

Figure-1: ECG obtained from a patient with chest pain.


MY Thoughts on the ECG in Figure-1:
The rhythm is sinus at ~80/minute. The PR interval is normal. The QRS is wide (I measure the QRS to be at least 0.14 second in duration).
  • The most time-efficient way to interpret a sinus rhythm with a wide QRS — is to figure out WHY the QRS is wide before proceeding further. There are 3 Possibilities (ECG Blog #204). These are: i) RBBB; ii) LBBB; or, iii) Neither RBBB nor LBBB — which defines the reason for QRS widening as IVCD (IntraVentricular Conduction Defect).
  • The 3 KEY leads to determine the type of conduction defect are left-sided leads I and V6 — and right-sided lead V1. The ECG in Figure-1 is consistent with complete RBBB because: i) There is an rSR' in lead V1; and, ii) There are upright R waves with a wide terminal S wave in lateral leads I and V6.
Resuming my systematic approach:
  • Finishing "Intervals" — the QTc does not appear excessively prolonged given the presence of RBBB.
  • There is no chamber enlargement.
  • Q Waves: There is no more than a tiny q wave in lead V6.
  • R Wave Progression: Not relevant given the RBBB.

ST-T Wave Changes:
Normally with RBBB — the ST segment and T wave are oppositely directed to the last QRS deflection in the 3 KEY leads:
  • Instead of the expected ST-T wave depression that should normally be seen in lead V1 with RBBB (ie, oppositely directly to the last QRS deflection, which is the positive R' complex) — there is ST elevation in lead V1 (above the dotted RED line in this lead — See Figure-2).
  • Instead of a purely upright T wave that should normally be seen in left-sided leads I and V6 with RBBB (ie, oppositely directed to the last QRS deflection, which is the negative wide terminal S wave) — there is a down-up biphasic T wave (BLUE — then RED arrows in these leads).
  • Biphasic T waves are seen in a number of other leads (including leads II, aVL; V2-thru-V5). This is not a normal finding — and suggests ischemia.
  • Normally with RBBB — the ST-T wave depression that is expected in anterior leads — does not continue into the lateral chest leads. It certainly should not increase, as it does here in lateral leads V5 and V6. ST depression should also not be seen in the limb leads as is seen here.
  • The other lead that manifests ST elevation is lead aVR — which shows slightly more ST elevation than is seen in lead V1.
  • The final finding of note in Figure-1 — is excessive fragmentation, in the form of extra notching that is most marked in leads V2, V3.

Figure-2: I've labeled the ECG in Figure-1 (See text).


Clinical IMPRESSION:
The ECG in Figure-1 shows sinus rhythm with QRS widening due to complete RBBB. The QRS is very wide and fragmented. There are abnormal biphasic T waves — diffuse ST depression beyond that expected for RBBB — and ST elevation in leads aVR and V1.
  • This patient almost certainly has significant underlying heart disease. 
  • The finding of ST depression with biphasic T waves in multiple leads, with ST elevation in lead aVR > V1 — strongly suggests diffuse subendocardial ischemia. Given the history of chest pain — cardiac cath is indicated to define the anatomy.
  • This ECG picture does not suggest acute coronary occusion. But severe (possibly multi-vessel) coronary disease should be suspected until proven otherwise.


P.S. I was asked if this ECG indicates prior "septal" infarction? Close observation of lead V1 reveals there is a very small-but-present initial positive deflection (r wave) in this lead — so although highly likely that this patient has significant underlying heart disease — we cannot make the diagnosis of "prior septal infarction" from this ECG alone.


==============================
Relevant ECG Blog Posts to Today's Post:
  • ECG Blog #204 — Reviews the ECG diagnosis of BBB (reviewed in the Video Pearl).
  • ECG Blog #271 — Reviews the concept of diffuse subendocardial ischemia.
  • ECG Blog #162 — Reviews a case of LBBB with acute STEMI.
  • ECG Blog #221 — How to diagnose acute MI when there is RBBB (reviewed in the Audio Pearl).
  • ECG Blog #298 — Reviews a case of RBBB/LAHB + Post. MI.





2 comments: