II. Definitions

  1. QRS Interval
    1. Electrical signal on EKG representing depolarization of the ventricle (immediately preceding contraction)
    2. Interval from the start of the Q Wave to the end of the S Wave

III. Normal findings: Duration

  1. Limb leads (I, II, III): 0.05 to 0.10
  2. Precordial leads (V1 to V6): 0.06 to 0.12

IV. Causes: Wide QRS or Prolonged QRS Complex (over 0.12)

  1. Abnormal interventricular conduction (e.g. Left Bundle Branch Block)
    1. See Bundle Branch Block
    2. Hypothermia
    3. Hyperkalemia
    4. Wolff-Parkinson-White Syndrome (WPW)
    5. Ventrciular ectopy
    6. Ventricular Tachycardia
  2. Medications (e.g. Toxin Ingestion or Overdose)
    1. Results from Sodium channel blockade
    2. Emergency management
      1. See Toxin Ingestion
      2. See Tricyclic Overdose
      3. Sodium Bicarbonate 1-2 amps IV push with repeat bolus until QRS narrows (adults)
    3. Causes
      1. Tricyclic Antidepressants
        1. Dry and sedated
      2. Cocaine
        1. Diaphoretic and agitated
      3. Diphenhydramine (Benadryl)
      4. Local Anesthetics (esp. Bupivacaine)
      5. Antiarrhythmics (e.g. Quinidine, Flecainide)
      6. Propoxyphene (not available in U.S.)
      7. Digoxin Toxicity
        1. Associated with frequent PVCs and sagging ST depression

V. Causes: Low QRS amplitude (<5 mm in limb leads)

VI. Causes: High QRS amplitude

  1. Evaluate for Left Ventricular Hypertrophy (LVH)
    1. Avoid using QRS amplitude alone to diagnose LVH in age <40-45 years old
  2. High Left Ventricular Voltage (HLVV)
    1. Large amplitude QRS Complexes are a normal finding in young, healthy athletes (not LVH)

VII. References

  1. Mattu (2016) Crit Dec Emerg Med 30(8):16
  2. Mattu (2021) Crit Dec Emerg Med 35(5):16

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Related Studies

Ontology: QRS complex duration (observable entity) (C0429025)

Concepts Organism Attribute (T032)
SnomedCT 251208001
LNC LP31031-5, MTHU019811
English QRS complex duration (observable entity), QRS duration, QRS complex duration
Spanish duración del complejo QRS (entidad observable), duración del complejo QRS

Ontology: QRS complex feature (C0429097)

Definition (NCI) An electrocardiographic finding that represents depolarization of the ventricular myocardium. Normally the ventricles are activated simultaneously.
Concepts Finding (T033)
SnomedCT 142119004, 164949005
LNC LP31569-4, MTHU024513
Dutch QRS-complex
French Complexe QRS
German QRS-Komplex
Italian Complesso QRS
Portuguese Complexo QRS
Spanish Complejo QRS, característica del complejo QRS (entidad observable), característica del complejo QRS, complejo QRS (entidad observable), complejo QRS
Japanese QRS群, QRSグン
Czech QRS komplex
English qrs complex, QRS Complex, QRS complex (observable entity), QRS complex, QRS complex feature (observable entity), QRS complex feature
Hungarian QRS komplex

Ontology: Electrocardiogram QRS complex (C0429098)

Concepts Finding (T033)
SnomedCT 164954001, 142126004
English ECG: QRS complex NOS, ECG: QRS complex NOS (observable entity), ECG QRS, Electrocardiogram QRS complex, electrocardiogram QRS complex, electrocardiogram: QRS complex, electrocardiogram: QRS complex (procedure), Electrocardiogram: QRS complex NOS, Electrocardiogram: QRS complex NOS (observable entity), ECG: QRS complex NOS (finding)
Italian Complesso QRS dell'elettrocardiogramma
Japanese 心電図QRS群, シンデンズQRSグン
Czech QRS komplex na elektrokardiogramu
Hungarian Elektrokardiogram QRS komplex
Spanish ECG: QRS complex NOS, electrocardiograma: complejo QRS, SAI, electrocardiograma: complejo QRS, SAI (entidad observable), electrocardiograma: complejo QRS, SAI (hallazgo), ECG: complejo QRS, SAI, Complejo QRS del electrocardiograma
Portuguese Complexo QRS (ECG)
Dutch elektrocardiogram QRS-complex
French Complexe QRS à l'électrocardiogramme
German Elektrokardiogramm QRS-Komplex

Ontology: electrocardiogram: QRS interval (C2168881)

Concepts Finding (T033)
English electrocardiogram intervals QRS, ECG intervals QRS, QRS interval on ECG, QRS interval, electrocardiogram: QRS interval (procedure), electrocardiogram: QRS interval