How well is your heart working? Let's talk about Cardiac Output!

Today we are going to talk about the heart, which is a very important organ in our body. Specifically, we are going to talk about how efficiently the heart pumps blood throughout our body, which is called cardiac output . Although these words may seem a bit new to you, they are actually quite simple. Let's see what this actually means, shall we?

What is cardiac output? Simply put...

Simply put, cardiac output is the total amount of blood your heart pumps throughout your body in one minute. This is usually measured in liters. Doctors calculate this with a simple equation. It requires two things:

1. Stroke Volume: This is the amount of blood your heart pumps into your body each time it beats, that is, with one heartbeat. This amount can vary. This amount of blood can increase or decrease depending on the health of your heart and whether you are at rest or engaged in some activity.

2. Heart Rate: You've probably heard of this one. This is the number of times your heart beats per minute. Normally, a healthy person's heart rate should be between 60 and 100 beats per minute when they are at rest. This increases when you exercise and decreases when you are at rest.

So, knowing both of these, we can find the total value using the equation Cardiac Output = Stroke Volume x Heart Rate .

Think of it this way. You're climbing a flight of stairs faster. Your muscles need more oxygen, right? So your heart rate increases, and your heart tries to increase the amount of blood it pumps at a time (stroke volume). That's when your cardiac output increases, because your body needs more blood and oxygen.

When do doctors look for this cardiac output?

Okay, now you have a question, at what point do doctors look for this cardiac output, right? There can be a number of reasons.

• If you find it difficult to exercise like you used to , or if you find it hard to breathe even with a little exertion.
• If your doctor suspects that you have a condition like heart failure , which is a condition in which the heart is unable to pump blood properly.
• If you need to accurately diagnose a disease.
• This is also measured to make sure that any medication, device, or treatment you've been given is working properly .

What symptoms can occur if cardiac output decreases?

If the amount of blood pumped by the heart to the body, or cardiac output, decreases, various parts of our body do not receive enough oxygen and nutrients. This can cause symptoms such as:

• It's very difficult to exercise: I feel dizzy and tired even after walking a short distance.
• Feeling very tired: Feeling exhausted even when just standing still.
• Swelling in your arms and legs: The legs, especially the ankles, may swell.
• Shortness of breath: Sometimes it can be difficult to breathe even when lying down.
• Nausea and vomiting.
• Abdominal pain.

Having these symptoms does not always mean that you have low cardiac output. However, if these symptoms persist, it is best to seek medical advice.

How do doctors measure cardiac output? There are several methods!

There are several methods doctors use to measure cardiac output. Some are very simple, while others require special equipment. Let's take a look at what they are:

• Oxygen consumption measurement: This measures how much oxygen a particular organ or tissue in your body is using. It is calculated by looking at the difference between the amount of oxygen in your arteries and the amount of oxygen in your veins, and then calculating it with the speed of blood flow.
• Comparing blood temperature: A special catheter is inserted into different parts of the heart, for example, the vena cava or the right atrium, and the temperature of the blood there is compared with the temperature of the blood in the pulmonary arteries that carry blood to the lungs. This is also called the thermodilution method .
• Measuring pressure and resistance: This can be found by taking the average pressure in your arteries (Mean Arterial Pressure) and dividing it by the resistance to blood flow through the blood vessels (Systemic Vascular Resistance).
• Portable devices: There are also portable devices that have special types of gases that you can breathe through your mouth.
• Using Electrodes: There is a test that involves placing about six electrodes on the chest. This measures heart rate and stroke volume, and calculates cardiac output.
• Transthoracic Echocardiography: This is a scan of the heart. It can give a good idea of ​​stroke volume.
• Heart MRI: Information about this can also be obtained from an MRI scan of the heart.
• Dye injection: This is done by injecting a special dye into the right side of the heart as blood enters it, and measuring how much dye comes out of the left side of the heart.

What should you expect when taking this test?

To most accurately measure cardiac output, your doctor will need to measure how much oxygen you breathe in and take blood samples from your artery and a special catheter placed in your lung artery (Catheter in Pulmonary Artery). This is usually done during a test called Right Heart Catheterization . On the day of this test, you will be able to know your cardiac output and the different pressures inside your heart.

What are the results? What do they tell us?

Okay, now let's see what these results say.

The cardiac output of a healthy person at rest is usually between 5 and 6 liters per minute .

However, in the case of a well-trained athlete, this value can be more than 35 liters per minute during exercise! This means that their hearts are working very efficiently.

Cardiac output increases when a non-athlete exercises, but not as much as an athlete. Also, during pregnancy, women's cardiac output increases above normal levels , because at that time, both the mother's body and the growing baby need blood supply.

What things affect our cardiac output?

Our cardiac output is not always the same. There are several factors that affect it. Let's look at the main factors that affect it:

• High Blood Pressure: If you have high blood pressure, your heart has to work harder to push blood through your arteries. Think of it like walking in a strong wind, because the pressure inside your arteries is higher. Also, if your blood pressure is higher in your lungs (perhaps due to scarring in your lungs or a condition like emphysema ), your heart has to work harder to pump blood there. This can reduce your cardiac output.
• Older age: As we age, the walls of our heart become thicker and stiffer. The heart does not fill with blood as quickly or as well as it used to. This can reduce the amount of blood it pumps to the body.
• If the heart has been damaged by a heart attack: If this happens, the heart may not be able to pump as much blood as it did before the heart attack. Also, an infection of the heart muscle called myocarditis can reduce the heart's pumping ability.
• Abnormal heart rhythms, such as atrial fibrillation: In this condition, the upper chambers of the heart (atria) are unable to pump blood properly and send it to the body through the lower chambers (mitra). Cardiac output is also reduced.
• Aortic Stenosis: This is a narrowing of the valve leading to the aorta: The aorta is the main blood vessel that carries blood to the body. So if the valve leading to it narrows, it cannot send enough blood to the body.
• Constrictive Pericarditis: If the protective sac around the heart, the pericardium , becomes tight, the heart cannot relax properly, fill with blood, and pump properly. This also impairs cardiac output.

How do we keep our cardiac output at a good level?

Okay, now we know why Cardiac Output is important and what factors affect it. So, what can we do to keep it at a good level? Keeping our heart strong and our blood vessels healthy is the key. Here are some things that can help with that:

• Regular exercise: Do something like walking, running, or cycling for at least 30 minutes a day.
• Control your cholesterol levels: Reduce your "bad" cholesterol (LDL) in particular, and keep your "good" cholesterol (HDL) levels at a healthy level.
• If you have diabetes , it is important to follow your doctor's instructions and maintain a healthy lifestyle.
• Minimize fatty and fried foods as much as possible: These can cause fat to build up in the blood vessels.
• Maintaining a healthy weight: Obesity puts extra strain on the heart.
• Avoid using tobacco products: Smoking is very harmful to the heart and blood vessels.
• If necessary, take medication as directed by your doctor and control your blood pressure.

Finally, things to remember (Take-Home Message)

It's important for your doctor to know how much blood your heart pumps, called cardiac output . It can help diagnose a disease, see if a treatment is working, or give you an idea of ​​your heart's health.

Once you have this information, your doctor can decide what the best options are to help you. If you are not sure about something, don't be afraid to ask your doctor questions. The more informed you are about your health, the better your chances of getting the best results. So, take care of your heart!

` Cardiac Output, Heart Rate, Stroke Volume, Heart Health, Heart Failure, Blood Pressure, Blood Circulation