This document provides a crib sheet for interpreting electrocardiograms (ECGs). It outlines the key steps and parameters to evaluate including rate, rhythm, intervals, axis, hypertrophy, and signs of infarction. Parameters like P waves, QRS width, PR and QT intervals, and ST segments are assessed. Reference values are provided to identify abnormalities. The crib sheet emphasizes a systematic approach and describes how certain conduction defects can alter the criteria used to diagnose conditions.
This document provides a crib sheet for interpreting electrocardiograms (ECGs). It outlines the key steps and parameters to evaluate including rate, rhythm, intervals, axis, hypertrophy, and signs of infarction. Parameters like P waves, QRS width, PR and QT intervals, and ST segments are assessed. Reference values are provided to identify abnormalities. The crib sheet emphasizes a systematic approach and describes how certain conduction defects can alter the criteria used to diagnose conditions.
This document provides a crib sheet for interpreting electrocardiograms (ECGs). It outlines the key steps and parameters to evaluate including rate, rhythm, intervals, axis, hypertrophy, and signs of infarction. Parameters like P waves, QRS width, PR and QT intervals, and ST segments are assessed. Reference values are provided to identify abnormalities. The crib sheet emphasizes a systematic approach and describes how certain conduction defects can alter the criteria used to diagnose conditions.
This document provides a crib sheet for interpreting electrocardiograms (ECGs). It outlines the key steps and parameters to evaluate including rate, rhythm, intervals, axis, hypertrophy, and signs of infarction. Parameters like P waves, QRS width, PR and QT intervals, and ST segments are assessed. Reference values are provided to identify abnormalities. The crib sheet emphasizes a systematic approach and describes how certain conduction defects can alter the criteria used to diagnose conditions.
Rate Divide 300 by the number of boxes in R-R Interval.
Rhythm First ensure that the patient is hemodynamically stable. Then assess the rhythm by use of the 5 KEY parameters which are most easily remembered by Watching your P's & Q's and the 3 R's ! Are there P waves? If so Are P waves upright in lead II? P waves should always be upright in lead II IF there is sinus rhythm (unless there is lead reversal/dextrocardia). Is the QRS complex wide or narrow? What is the Rate? Is the rhythm Regular? Are P waves Related (ie, "married" with fixed PR interval) to the QRS? IF P waves are married then they are being conducted to the ventricles.
Intervals Look at intervals early in the process! The PR Interval is prolonged IF >0.20-0.21 second (if clearly more than a LARGE box in duration). The QRS Complex is wide IF >0.10 sec. (if more than HALF a large box). The QT Interval is prolonged IF clearly more than half the R-R interval (provided that heart rate is not more than 100 beats/minute). IF the QT is prolonged Think Drugs- Lytes-CNS (List #3).
KEY Point IF the rhythm is sinus, but the QRS is wide then STOP and figure out why it is wide (RBBB, LBBB, IVCD,WPW) before proceeding further. Criteria for infarction, ischemia, and chamber enlargement will all be different IF there is a conduction defect
Axis Determine the axis quadrant by looking at lead I (at 0 ) and lead aVF (at +90 ): The axis is normal IF the net QRS deflection is positive in leads I and aVF (defines axis to be between 0 to +90 ). There is RAD IF the net QRS deflection is negative in I, but positive in aVF (Think RVH, LPHB or normal variant). There is LAD IF the net QRS is positive in I, but negative in aVF. There is pathologic LAD = LAHB IF the net QRS deflection is more negative than positive in lead II. The axis is indeterminate IF the net QRS deflection is negative in leads I and aVF (Think RVH, COPD, obesity).
- Open or Close BOOKMARKS -
Hypertrophy (chamber enlargement): The "magic numbers" for LVH are 35 (deepest S in V1,V2 plus tallest R in V5,V6 in a patient at least 35 years of age) and 12 (for the R in aVL). True chamber enlargement is much more likely IF "strain" also present! There is RAA (P Pulmonale) IF P waves are prominent (2.5 mm tall) and peaked (ie, "uncomfortable to sit on") in the pulmonary leads (II, III, and aVF ). There is LAA (P Mitrale) IF P waves are notched ("m"-shaped) in mitral leads (I, II, or aVL) or if the P in V1
has a deep terminal negative component. Consider pulmonary disease IF there is RAA, RAD (or indeterminate axis), incomplete RBBB (or rSr' pattern in lead V1), low voltage, or persistent precordial S waves. Consider RVH IF there is also a tall R wave in V1 and right ventricular "strain". Criteria for LVH/RVH are different when there is BBB.
Infarct (= Q-R-S-T changes) Look at all leads (except perhaps lead aVR ) for the following: Q Waves Small (normal septal q waves) are commonly seen in lateral leads (I,aVL,V4,V5,V6); moderate or large-sized Q waves are normal (as an isolated finding) in leads III, aVF, aVL, and V1. R Wave Progression Does transition occur as it normally should between leads V2-to-V4? Is there a Tall R in Lead V1? (List #6). Normally the QRS is predominantly negative in right-sided lead V1. Is there an rSr' pattern in lead V1? (which could be a normal variant or incomplete RBBB). ST Segments Judge ST segment deviation (elevation or depression) with respect to the PR segment baseline. Much more than the amount of ST segment deviation Focus on shape ("smiley" or "frowny). T Waves May normally be inverted in leads III, aVF, aVL, and V1 (these are the same leads that may normally manifest isolated Q waves). Remember that criteria for ischemia/infarction are different when there is BBB.
Suggested Approach: Use the above as a guide for descriptive analysis; then formulate your clinical impression. Whenever possible WRITE OUT your findings (but even when time is short be systematic).
(CIPS Series on the Boundaries of Psychoanalysis) Harriet I. Basseches, Paula L. Ellman, Nancy R. Goodman - Battling the Life and Death Forces of Sadomasochism_ Clinical Perspectives-Karnac Books (201