All ICD10 Codes
Chapter 9

I00–I99: Diseases of the Circulatory System

Diseases of the Circulatory System diagnostic classification updated for 2026.

Chapter Instructions

Excludes2(Not included here. Code separately if applicable.)
  • certain conditions originating in the perinatal period (P04-P96)
  • certain infectious and parasitic diseases (A00-B99)
  • complications of pregnancy, childbirth and the puerperium (O00-O9A)
  • congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
  • endocrine, nutritional and metabolic diseases (E00-E88)
  • injury, poisoning and certain other consequences of external causes (S00-T88)
  • neoplasms (C00-D49)
  • symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
  • systemic connective tissue disorders (M30-M36)
  • transient cerebral ischemic attacks and related syndromes (G45.-)
All CodesBillable Only
Internal Codes
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  • I44.4—

    Left anterior fascicular block

  • I44.5—

    Left posterior fascicular block

  • I44.6—

    Other and unspecified fascicular block

  • I44.60—

    Unspecified fascicular block

  • I44.69—

    Other fascicular block

  • I44.7—

    Left bundle-branch block, unspecified

  • I45—

    Other conduction disorders

  • I45.0—

    Right fascicular block

  • I45.1—

    Other and unspecified right bundle-branch block

  • I45.10—

    Unspecified right bundle-branch block

  • I45.19—

    Other right bundle-branch block

  • I45.2—

    Bifascicular block

  • I45.3—

    Trifascicular block

  • I45.4—

    Nonspecific intraventricular block

  • I45.5—

    Other specified heart block

  • I45.6—

    Pre-excitation syndrome

  • I45.8—

    Other specified conduction disorders

  • I45.81—

    Long QT syndrome

  • I45.89—

    Other specified conduction disorders

  • I45.9—

    Conduction disorder, unspecified

  • I46—

    Cardiac arrest

  • I46.2—

    Cardiac arrest due to underlying cardiac condition

  • I46.8—

    Cardiac arrest due to other underlying condition

  • I46.9—

    Cardiac arrest, cause unspecified

  • I47—

    Paroxysmal tachycardia

  • I47.0—

    Re-entry ventricular arrhythmia

  • I47.1—

    Supraventricular tachycardia

  • I47.10—

    Supraventricular tachycardia, unspecified

  • I47.11—

    Inappropriate sinus tachycardia, so stated

  • I47.19—

    Other supraventricular tachycardia

  • I47.2—

    Ventricular tachycardia

  • I47.20—

    Ventricular tachycardia, unspecified

  • I47.21—

    Torsades de pointes

  • I47.29—

    Other ventricular tachycardia

  • I47.9—

    Paroxysmal tachycardia, unspecified

  • I48—

    Atrial fibrillation and flutter

  • I48.0—

    Paroxysmal atrial fibrillation

  • I48.1—

    Persistent atrial fibrillation

  • I48.11—

    Longstanding persistent atrial fibrillation

  • I48.19—

    Other persistent atrial fibrillation

  • I48.2—

    Chronic atrial fibrillation

  • I48.20—

    Chronic atrial fibrillation, unspecified

  • I48.21—

    Permanent atrial fibrillation

  • I48.3—

    Typical atrial flutter

  • I48.4—

    Atypical atrial flutter

  • I48.9—

    Unspecified atrial fibrillation and atrial flutter

  • I48.91—

    Unspecified atrial fibrillation

  • I48.92—

    Unspecified atrial flutter

  • I49—

    Other cardiac arrhythmias

  • I49.0—

    Ventricular fibrillation and flutter

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