The Anatomy of Congestive Heart Failure

May 11, 2021


In a normally functioning heart, oxygen-poor blood enters the right side of the heart through the inferior and superior vena cava and enters the right atrium.  As the atrium contracts, blood flows from the right atrium into the right ventricle through the open tricuspid valve.

When the ventricle is full, the tricuspid valve closes to prevent blood from flowing back into the right atrium when the ventricle contracts. As the ventricle contracts, blood leaves the heart through the pulmonic valve, into the pulmonary artery and to the lungs where it is oxygenated.

On the left side of the heart the pulmonary vein empties oxygen-rich blood from the lungs into the left atrium of the heart. As the atrium contracts, blood flows from the left atrium into the left ventricle through the open mitral valve.

When the ventricle is full, the mitral valve closes to prevent blood from flowing back into the left atrium when the ventricle contracts. As the ventricle contracts, oxygen-rich blood leaves the heart through the aortic valve, into the aorta and to the arteries, then into the veins.

However not all hearts function at optimal levels. Congestive heart failure occurs when the heart isn’t able to pump enough blood to meet the needs of the body. This results in a decrease in blood supply to the body tissue which leads to a decrease in oxygen and a failure to meet other metabolic requirements.

When this happens, less blood is being filtered by the kidneys which results in less fluid being circulated into urine. The extra fluid in circulation can build up in the lungs, the liver, around the eyes, and in the legs and result in pulmonary and/or circulatory congestion.


Symptoms of congestive heart failure can be shortness of breath, fatigue, edema in legs/ankles/feet, persistent cough or wheezing, rapid weight gain from fluid retention and chest pains.


The two most common causes of heart failure are:

  • Coronary artery disease: Narrowing or blockage of the small blood vessels that supply blood and oxygen to the heart can weaken the heart muscle over time, which can then lead to a decreased ability to pump blood out of the heart.
  • Hypertension: If hypertension is not well controlled, it can lead to muscle weakening.

While coronary artery disease and hypertension attribution to the most common causes, other heart conditions that can cause or contribute to heart failure include:

  • Congenital heart disease
  • Myocardial infarction
  • Leaky or narrowed heart valves
  • Severe infection that weakens heart muscle
  • Arrhythmias


Congestive heart failure can be diagnosed with the use of one or more of the following diagnostic studies:

  • EKG- Atrial and ventricular arrhythmias may be common findings in patients with congestive heart failure
  • Chest x-ray- Cardiomegaly or signs of increased pulmonary venous pressure
  • Echocardiography- Helps assess the size, mass and function of the left ventricle
  • Angiography- Can provide detailed measurements of ventricular filling pressures and indices of left ventricular diastolic relaxation rate
  • Labs- serum B-type natriuretic peptide (BNP)

What is Ejection Fraction?

The measurement of ejection fraction is often used to aid in diagnosing congestive heart failure. Ejection fraction is a measurement of the percentage of blood leaving your heart each time it contracts. The ejection fraction is usually measured only in the left ventricle.  The left ventricle is the heart’s main pumping chamber.

  • If the ejection fraction is 60%, this means the heart is pumping 60% of the blood from the left ventricle with each contraction.
  • Left ventricular ejection fraction of 55% or higher is considered normal.
  • Left ventricular ejection fraction of 50% or lower is considered reduced.

Types of Congestive Heart Failure

There are three main types of congestive heart failure – systolic heart failure, diastolic heart failure & a combination of systolic and diastolic heart failure.

  1. Systolic heart failure: Occurs when the ability of the heart to contract decreases. This may also be referred to as:
  • Heart failure with reduced ejection fraction (HFrEF)
  • Heart failure with low ejection fraction
  • Heart failure with reduced systolic function
  1. Diastolic heart failure: Occurs when the heart has a problem relaxing between contractions to allow enough blood to enter the ventricles
  • May also be referred to as heart failure with preserved ejection fraction (HFpEF)
  1. Combined systolic and diastolic heart failure: Occurs when the heart has both decreased abilities to contract and problem relaxing between contractions

Heart failure is differentiated by whether it affects the right or left ventricle.

  • Left-sided heart failure: Due to the accumulation of excess fluid behind the left ventricle
    • 1, Left ventricular failure, unspecified
      • Includes dyspnea, orthopnea, bronchospasm, cardiac asthma, edema of lung with heart disease, edema of lung with heart failure, left heart failure, pulmonary edema with heart disease, and pulmonary edema with heart failure. (No additional codes assigned for these conditions)
    • Right-sided heart failure: ordinarily follows left-sided failure
      • 814, Right heart failure due to left heart failure
        • Code also the type of left ventricular failure, if known
      • 82, Biventricular heart failure
        • Right heart failure with left heart failure, but not due do left heart failure


All codes for heart failure include any associated pulmonary edema – no additional code is assigned.

Code assignment may be based on documentation of HFrEF (heart failure with reduced ejection fraction) or HFpEF (heart failure with preserved ejection fraction).

  • Acute: Occurs when there has been sudden damage to the heart.
    • May be caused by myocardial infarction, thrombus in the heart, or severe infection.
  • Chronic: Occurs slowly over time. Usually due to an underlying condition such as hypertension or heart disease.
  • Acute on chronic: Occurs when the patient with chronic congestive heart failure suffers an acute exacerbation.
    • May be documented as acute decompensation.

When a patient has a known history of diastolic or systolic congestive heart failure, a code for chronic heart failure is assigned:

  • 22, Chronic systolic (congestive) heart failure
  • 32, Chronic diastolic (congestive) heart failure

Heart dysfunction without mention of heart failure: It is not appropriate to assume the patient is in heart failure if only “diastolic dysfunction” or “systolic dysfunction” is documented.  This takes us to I51.89, Other ill-defined heart diseases. In this case, you should query physician for clarification.


ICD-10-CM presumes a causal relationship between hypertension and heart involvement. The two conditions are linked by the term “with” in the Alphabetic Index. They should be coded as related even if the physician documentation does not explicitly link them. One exclusion would be: physician documentation that clearly states the hypertension is unrelated to the heart disease or another cause is identified.

Hypertension with heart conditions classified to I50.- or I51.4 – I51.7, I51.89, I51.9 are assigned to a code from category I11, Hypertensive heart disease. Use additional code(s) from category I50, Heart failure, to identify the type(s) if heart failure.


  • American Academy of Family Physicians, Essentials of the Diagnosis of Heart Failure, March 1, 2000, Fadi Shamsham, M.D. and Judith Mitchell, M.D.
  • ICD-10-CM and ICD-10-PCS Coding Handbook, Chapter 27, Heart Failure
  • ICD-10-CM Official Guidelines for Coding and Reporting, Section I.C.9.a.1).


Author: Sandy Hall, CCS, COC, CPC