How Does the Heart Work?
The heart is a muscle about the size of your fist that pumps blood through your circulatory system to deliver oxygen and nutrients to all parts of the body. When the body's cells get all the nutrients they need, the body can function normally.
The heart has four chambers, two upper chambers (atria) and two lower chambers (ventricles). Between the chambers are flaps called valves, which ensure that the blood flows in the right direction.
The heart pumps blood in a synchronized four-step process:
- Oxygen-poor blood enters the heart through the right atrium (the upper chamber closest to your right hand).
- The blood then passes down into the right ventricle and through the pulmonary artery to the lungs, where it receives oxygen.
- The oxygenated blood then returns to the heart, this time through the pulmonary veins into the left atrium.
- The blood passes through the left ventricle into the aorta, from which it is pumped out to the rest of the body.
What Is Heart Failure?
Heart failure, also known as congestive heart failure (CHF), is a syndrome associated with symptoms and signs of excess fluid. There are two main types of heart failure classification:
- Systolic Heart Failure: The heart's lower chambers (ventricles) become too weak to contract and pump out enough blood to meet the body's needs, resulting in shortness of breath and other heart failure symptoms.
- Diastolic Heart Failure: The heart muscle becomes too stiff to relax and expand to fill with enough blood. This causes the heart to pump less blood, resulting in the backup of fluid in the lungs and other heart failure symptoms.
The heart can attempt to compensate for either of these conditions by:
- Stretching its chambers to hold more blood
- Increasing in muscle mass to increase its pumping power
- Pumping faster to increase its output
The body can also try to compensate for the decreased blood flow, either by narrowing the veins and arteries to keep blood pressure up, or by diverting blood away from less essential tissues to ensure that the most vital organs receive enough blood flow.
These temporary measures may mask the problem—which is why many people with heart failure are at first unaware of their condition—but they do not solve it. Eventually the heart simply cannot keep up and the patient begins to experience the symptoms of heart failure such as fatigue and shortness of breath.
What Are the Stages of Heart Failure?
There are four main stages of heart failure:
Stage A (pre–heart failure)
- The patient is at a high risk for developing heart failure in the future.
- The patient may have:
- Coronary artery disease
- Family history of cardiomyopathy
Stage B (asymptomatic heart failure)
- The patient has been diagnosed with heart failure but exhibits no symptoms of the disease.
- The patient may have:
- Had a prior heart attack
- Left ventricular systolic dysfunction (difficulty of the left ventricle to empty or eject the blood from its chamber)
- Been diagnosed with valvular disease.
Stage C (symptomatic heart failure)
The patient has been diagnosed with heart failure and is experiencing symptoms such as:
- Shortness of breath
- Reduced tolerance for physical activity
Stage D (end-stage heart failure)
The patient continues to show progressive signs and symptoms of heart failure even after standard treatment.
Learn more about heart failure:
- Causes of Heart Failure
- Symptoms of Heart Failure
- How Heart Failure Is Diagnosed
- Treatment for Heart Failure
For more information about heart failure treatment at the Houston Methodist DeBakey Heart & Vascular Center or to make an appointment, please call us at 713-DEBAKEY (713-332-2539) or complete our online contact us form.