CHF Deep Dive

Congestive heart failure makes your heart weak. It makes you feel tired and worn-down. It makes it hard to breathe. And your legs swell. And, CHF can give you pneumonia.

CHF is a terminal heart condition, or a heart condition that can end with the patient dying. Patients with advanced CHF have severely limited activities. They are homebound and need help with basic daily activities like bathing, dressing and toileting.

CHF patients get worn out quickly, or have decreased exercise tolerance (in medical talk, exercise refers not just to sports, but also to normal activities like walking or getting out of a chair):

CHF is a terminal heart condition, or a heart condition that can end with the patient dying. Patients with advanced CHF have severely limited activities. They are homebound and need help with basic daily activities like bathing, dressing and toileting.

CHF patients get worn out quickly, or have decreased exercise tolerance (in medical talk, exercise refers not just to sports, but also to normal activities like walking or getting out of a chair):

Heart failure is complicated. But the answer to that question comes down to one thing, and one thing only—Oxygen.

Our bodies need oxygen for everything they do. Our muscles use oxygen when they move (and they can’t move without oxygen). Our brains use oxygen to think, and we can’t think without using oxygen. Our intestines use oxygen to help them digest food, and they can’t…well, you probably get the picture.

Think about oxygen this way. We breathe about 12 times a minute, 720 times an hour, and 17,280 times a day, all of those breaths for one reason—to get oxygen out of the air. Then our lungs hand that oxygen over to our blood, which carries that oxygen to the heart, which pumps that oxygen-rich blood, through our blood vessels, all around our body with each one of its 115,200 beats a day—Between the breathing and the heartbeats, that’s a lot of resources just to send oxygen around the body. But oxygen is that important.

It’s bad. When our brain doesn’t get enough oxygen we get confused, dunder-headed and depressed. When our muscles don’t get enough oxygen, they get weak and ache. Our digestive system stops digesting food. Overall, we feel run down.

And, obviously, we feel short of breath.

Some people with CHF experience all this stuff all the time. It’s terrible.

But it’s especially bad when we exert energy (by walking up stairs, for example) and need extra oxygen to support our extra effort. They we’ll feel really wiped out and our muscles will feel really achy and weak.

The heart has one job-- to pump oxygen-rich blood through our blood vessels, all around our body to the places that need it.

If our heart is weak and pumping weakly and slowly, it doesn’t matter how much oxygen is in the blood. Not enough blood (or oxygen) will be moving around the body fast enough. Not enough oxygen will get to your brain — you’ll feel confused, dunder-headed and depressed. Not enough oxygen will get to your muscles — your muscles will feel achy and weak. Not enough oxygen will make it to your digestive system—you’ll digest your food too slowly. And etc.

And you won’t be able to do things that require a lot of energy, like climbing stairs or taking out the garbage, without feeling really wiped out.

You might even feel really wiped out when you’re just sitting in a chair watching TV.

CHF involves one of two forms of heart damage, both of which lead to the exact same problem - reduced cardiac output - With each beat, the heart pumps less blood than normal.

A normal heart pumps out a little more than ¼ cup of blood with each beat. That ¼ cup is the normal stroke volume of a heartbeat. (A stroke is a single heartbeat, and volume refers to the amount of blood pumped with each stroke/heartbeat—1/4 cup.)

Here’s another way to look at it. The heart is a chamber, just like a balloon is a chamber. While a balloon holds air, a heart holds blood. The average heart holds about ½ a cup of blood (right before it beats), and then beats out about 65% of that ½ cup, or a little more than ¼ cup with each beat.

That “65%” is each beat’s ejection fraction, or the percentage of blood held by the heart (right before it beats) that is pumped out.

Here are the two things that cause reduced cardiac output - “dilated cardiac myopathy” and “heart failure with preserved ejection fraction and remodeling.” Remember, a person with heart failure has one or the other, but not both:

When a heart has dilated cardiac myopathy - In the same way, when a heart has dilated cardiac myopathy, it has become stretched larger than normal. Like the stretched balloon, it has become flabby and weak. When it squeezes to push blood out with each beat, it pushes, or pumps, weakly: not so much blood is pushed out.

[If you’re interested in what those ten-dollar-words mean: dilated (made large, or spread out) cardiac (heart) myopathy (injured muscle).]

Hearts that have heart failure because of dilated cardiac myopathy have what’s called heart failure without preserved ejection fraction. The heart is a chamber, just like a balloon. While a balloon holds air, a heart holds blood. The average heart holds about ½ cup of blood (right before it beats), and then beats out about 65% of that ½ cup, or a little more than ¼ cup with each beat.

But a heart with dilated cardiac myopathy pumps out less than 50% of the blood it’s holding, even as little as 12%. So a heart with dilated myopathy can pump out anywhere from just 8 tablespoons, to as little as 2 tablespoons of blood with each beat.

That remodeled heart, is just as strong as a normal heart (unlike a heart with dilated cardiac myopathy, which is weak). That’s what preserved ejection fraction is about. The heart works by filling up with blood, and then pumping, or squeezing it out. The average heart squeezes out about 65% of its contents (the blood in it) with every beat.

The most obvious place is in those swollen legs.

But the most dangerous place is in the lungs. (A main reason for this is that water in the lungs puts people at risk for pneumonia, but we’ll talk about that later.)

Loss of appetite - After having a weak heart, the main thing that happens to people with CHF is that they collect water in their bodies.

When you have water collecting in your lungs, it can be really hard to breath. The reason is simple—The water blocks oxygen. Remember how the lungs hand oxygen over to the blood so it can be delivered, through the blood vessels, all over the body.

Weight loss - After having a weak heart, the main thing that happens to people with CHF is that they collect water in their bodies.