Heart Failure: Compensation by the Heart and Body
Heart failure means that your heart muscle doesn't pump as much blood as your body needs. Because your heart cannot pump well, your heart and your body try to make up for it. This is called compensation.
Your body has a remarkable ability to compensate for heart failure. The body may do such a good job that many people don't feel symptoms in the earlier stages of heart failure. It is only when your body isn't able to compensate enough that you will begin to experience symptoms.
Compensation may help your body adjust to the effects of heart failure in the short term. But over time it can make heart failure worse by further enlarging the heart and reducing the pumping ability of the heart.
How does the body compensate?
With heart failure, the heart doesn't pump as well as it should. So your body doesn't get enough blood and oxygen. When this occurs, the body believes that there isn't enough fluid inside its vessels. The body's hormone and nervous systems try to make up for this by increasing blood pressure, holding on to salt (sodium) and water in the body, and increasing heart rate. These responses are the body's attempt to compensate for the poor blood circulation and backup of blood.
How does the heart compensate?
Your heart's goal in compensating for heart failure is to maintain your cardiac output. Cardiac output is the amount of blood your heart is able to pump in 1 minute. The problem in heart failure is that the heart isn't pumping out enough blood each time it beats (low stroke volume). To maintain your cardiac output, your heart can try to:
How does the heart know to beat faster? Your brain signals your heart to beat faster by sending messages to your heart's electrical system, which controls the timing of your heartbeat. When your cardiac output is low, your adrenal glands also release more norepinephrine (adrenaline), which travels in the bloodstream and stimulates your heart to beat faster. Although beating faster helps to maintain cardiac output as the stroke volume falls, a faster heart rate can be counterproductive because it allows less time for the ventricle to fill with blood after each heartbeat. Also, a very fast heart rate can itself weaken the heart muscle over time.
How does the heart increase its stroke volume? To increase its stroke volume, your heart can try to:
What happens when your body can no longer compensate?
If your body can no longer compensate for heart failure, you will begin to have symptoms, which consist of two major types:
How long does it take before the body stops compensating for heart failure? Your body can compensate for heart failure for a long time, often for many years. But the duration of compensation can be extremely variable and depends on the cause of your heart failure and whether you have other medical problems.
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