EKG / ECG basics
Formal Definition
EKG (German: Elektrokardiogramm) and ECG (English: electrocardiogram) — interchangeable abbreviations for the surface recording of cardiac electrical activity using electrodes placed on the limbs and chest wall, capturing the heart's depolarization and repolarization sequence as a 12-lead tracing (10 electrodes producing 12 distinct views of electrical activity); fundamental tool for evaluating rhythm, rate, axis, intervals, ischemia/infarction (ST elevation/depression, T-wave inversion, Q waves), chamber enlargement, and congenital abnormalities; standard reference for cardiac emergencies (STEMI activation).
How It's Used on the Ward
"EKG" or "ECG" — the rhythm strip/performed on essentially every inpatient admission and any cardiac-related complaint; tells the team (1) rate, (2) rhythm, (3) axis, (4) intervals (PR, QRS, QTc), (5) acute ischemic changes (STEMI), (6) prior changes (Q waves from old MI, LVH patterns, BBB); "telemetry" — continuous EKG monitoring in real time for inpatients on monitored units.
Example
""62-year-old man, acute crushing chest pain x45 minutes, presenting to ED. Acutely endorsed EKG within 10 minutes: rate 88, sinus rhythm, normal axis, PR 142, QRS 92, QTc 412. ST elevation 3 mm in leads II, III, aVF with reciprocal depressions in I and aVL. Pattern is consistent with inferior STEMI. Code STEMI activated: cardiology paged, cath lab activated within 15 minutes, patient directly to cath lab for primary PCI; LAD-distal culprit lesion stented.""
Clinical Context
Leads: standard 12-lead EKG includes 6 limb leads (I, II, III, aVR, aVL, aVF) and 6 precordial leads (V1-V6). Each lead shows the heart from a different electrical viewpoint. Special leads: posterior leads V7-V9, right-sided leads (V3R-V5R) for RV infarction, lead-monitoring in real time (telemetry) typically only shows leads II and V (or whatever two are best). Reading approach: (1) Rate (count QRS complexes in 6 seconds ×10, or large boxes method). (2) Rhythm (regular vs irregular, P wave before each QRS, P wave morphology consistent). (3) Axis (lead I positive = leftward axis; lead aVF positive = inferior axis; quadrant method). (4) Intervals (PR 120-200ms; QRS <120ms; QTc <450ms in men, <460ms in women). (5) Morphology (R-wave progression V1-V6; Q waves pathologic if >40ms in two contiguous leads); ST elevation (STEMI criteria: ≥1 mm in 2 contiguous leads except men V2-V3 ≥2 mm; for posterior MI: ST depression in V1-V3 with upright T wave). ST depression, T-wave inversion = ischemia/reperfusion/other causes. Q waves ~ pathologic if >1mm wide and >2mm deep. Common acute findings requiring code-level action: ST elevation MI (activation of cath lab), unstable bradycardia, sustained VT, complete heart block, new LBBB with symptoms suggestive of MI (Sgarbossa criteria for STEMI in LBBB). Documented daily in ICU, on telemetry floors, prior to cardiac procedure/contrast, after any rate/rhythm complaint. Pre-procedence note: in many countries and at most US institutions, "ECG" and "EKG" are synonymous; the German EKG persists as historical tradition.