Diseases of the circulatory system
This chapter covers ICD-10-CM codes in the range I00-I99 for diseases of the circulatory system. Covers diseases of the heart and blood vessels including hypertension, ischemic heart disease, and cerebrovascular diseases.
Chapter Overview
Key Statistics
- •Contains 10 categories and 49 total codes
- •Includes 4 billable codes and 45 non-billable codes
- •Chapter range: I00-I99
Clinical Relevance
Critical for cardiovascular conditions including hypertension, heart disease, and stroke. Extensively used in cardiology, emergency medicine, and primary care.
Documentation Requirements
Requires blood pressure readings, ejection fraction, vessel involvement, and acute vs chronic status. MI documentation needs timing and vessel specificity.
Special Considerations
Hypertension coding includes controlled vs uncontrolled status. Acute MI has specific time-based coding rules and requires vessel specification.
Categories in this Chapter
Acute rheumatic fever
Chronic rheumatic heart diseases
Hypertensive diseases
Ischemic heart diseases
Pulmonary heart disease and diseases of pulmonary circulation
Other forms of heart disease
Cerebrovascular diseases
Diseases of arteries, arterioles and capillaries
Diseases of veins, lymphatic vessels and lymph nodes
Other and unspecified disorders of the circulatory system
Chapter-Specific Coding Guidelines
General Guidelines for Diseases of the circulatory system:
- Hypertension coding requires documentation of type and severity
- Acute myocardial infarction has specific time-based coding rules
- Heart failure requires specification of systolic vs diastolic dysfunction
- Combination codes exist for hypertension with related conditions
Documentation Requirements:
- •Specific type of cardiovascular condition
- •Acute vs chronic manifestation
- •Location and extent of condition (e.g., vessel involved)
- •Functional status and symptoms
- •Underlying causes when applicable
Sequencing Rules:
- Acute conditions typically sequenced before chronic
- Use combination codes when available
- Complications sequence according to treatment focus
- Multiple cardiovascular conditions require careful sequencing
When to Use:
- ✓For primary cardiovascular conditions
- ✓When cardiovascular disease affects treatment
- ✓For acute cardiac events
- ✓When monitoring chronic cardiovascular conditions
When NOT to Use:
- ✗Personal history without current symptoms (use Z87.- codes)
- ✗Normal cardiac function findings
- ✗Screening encounters without abnormalities
- ✗Congenital heart conditions (use Q20-Q28 codes)
Special Considerations:
- ⚠AMI codes have 4-week initial period rules
- ⚠Hypertension may be controlled or uncontrolled
- ⚠Heart failure staging affects code selection
- ⚠Postoperative complications have specific coding
Version Updates
2025 updates emphasize precision cardiology, genetic cardiomyopathies, and advanced heart failure management.
Recent Updates:
Heart Failure Phenotyping
Enhanced codes for heart failure with preserved ejection fraction (HFpEF) subtypes
Impact: Better classification of heart failure phenotypes
Genetic Cardiomyopathy Markers
New codes for specific genetic variants in cardiomyopathies
Impact: Improved precision medicine in cardiology
Implementation Guidance:
- •Update heart failure documentation practices
- •Train on genetic testing documentation
- •Review cardiac catheterization coding
- •Implement quality measures for cardiovascular coding
Upcoming Changes:
- →Expanded structural heart disease codes in 2026
- →Enhanced coding for cardiac devices and monitoring
- →New categories for artificial intelligence-guided diagnosis
Related Resources
Essential resources for cardiovascular coding, clinical guidelines, and quality measures.
Official Documentation:
Tools and References:
Frequently Asked Questions
How do I distinguish between different types of heart failure?
Document ejection fraction, diastolic dysfunction, and clinical symptoms. Use I50.1 for left ventricular failure, I50.9 for unspecified heart failure.
What's the difference between acute and chronic myocardial infarction coding?
Acute MI (I21.-) is used for the first 4 weeks. After 4 weeks, use I25.2 for old myocardial infarction.
How do I code hypertension with related conditions?
Use combination codes when available (e.g., I11.- for hypertensive heart disease). Otherwise, code hypertension and related condition separately.