Cardiac arrest, or sudden cardiac arrest, is when your heart suddenly stops beating. There is no pulse so without enough blood flow, your brain and body stop getting oxygen. Call 911 right away and start CPR if you think this is happening. It’s a life-threatening emergency.

You’ll quickly lose consciousness, collapse, and stop breathing. Your pulse stops. You might feel dizzy or lightheaded before it happens. You may also get chest pain, a sick feeling, or shortness of breath. Your heart may beat really fast right before it stops. But cardiac arrest can happen without any warning signs.

Your heart runs on electricity. Certain problems can mess up the signals that keep it pumping like it should. These glitches can cause irregular heartbeats, or arrhythmias. There are different kinds of arrhythmias. Most aren’t harmful. But there’s one called ventricular fibrillation, or v-fib, that’s most likely to trigger cardiac arrest.

Most people who have cardiac arrest also have coronary artery disease, or ischemic heart disease. The plaque that builds up in your blood vessels can slow or stop blood from flowing into your heart. That can cause a heart attack that hurts your heart’s cells and electrical system. 

Hypertrophic cardiomyopathy (HCM) can thicken your heart muscle, which lessens blood flow through your heart. That can disrupt your heart’s electrical system. You may get an abnormal heart rhythm called ventricular arrhythmia. It may happen because of your genes, high blood pressure, or for unknown reasons.

Unlike cardiac arrest, your heart usually keeps beating during a heart attack. But blood flow gets cut off, which means your heart doesn’t get enough oxygen. That can damage your heart muscle. While these are two distinct conditions, they’re also linked: a heart attack can disrupt your heart’s electrical system and lead to cardiac arrest. 

Cardiac arrest is a sudden, life-threatening event. Heart failure is serious, but it doesn’t mean your heart has stopped. It’s just that your heart muscle is weak. At some point, it won’t be able to pump enough oxygen-rich blood to the rest of your body. That can leave you feeling out of breath and tired when you do anything active, including doing chores or walking around your house.

Your chances of cardiac arrest are highest if have heart disease. But your odds go up if you:

• Have a personal or family history of arrhythmias
• Are an older male
• Smoke or misuse drugs or alcohol
• Have had one or more heart attacks
• Have diabetes, high blood pressure, heart failure, or kidney disease
• Have obesity or aren’t very active

Sudden strong feelings can cause deadly arrhythmias in some people. Out-of-control anger is the most common one linked to cardiac arrest. But extreme shock (good or bad), powerful sadness, and other negative emotions may mess with your heart’s electrical system. Tell your doctor if you have anxiety, depression, or can’t control your emotions. A mental health professional can help manage your moods.

Cardiac arrest can cause death within minutes, so you’ll need medical help ASAP. If done fast enough, a device called a defibrillator can shock your heart into beating again. Police or other emergency responders usually have these devices on hand and know how to use them. If you’re in a public place, there may be an automated external defibrillator (AED) nearby. You don’t need training to use these. 

First, call 911 or have someone else go for medical help. Then follow the directions that come with the automated external defibrillator (AED). The AED can check the activity in the person’s heart. The device will tell you if, when, and how you need to deliver the pre-programmed electric shock. An AED may be able to send more than one pulse. After you shock the person’s heart, you may need to do CPR until help arrives.

Your medical team will monitor your heart for a while. They’ll try to figure out what caused your cardiac arrest so they can lessen the chances it’ll happen again. You may need an implantable cardioverter defibrillator (ICD). If you have heart disease, you may need to take medicine, make lifestyle changes, or have surgery to open your narrowed or blocked vessels.

A heart doctor, or cardiologist, can help you come up with a long-term treatment plan. You may also need to see a cardiac electrophysiologist. Those are doctors who specialize in electrical problems that affect the heart. But no matter who you go to, they’ll likely give you some blood tests and check the electrical activity in your heart. 

 Several tests can help detect your chances of cardiac arrest:

• Electrocardiogram (EKG): Records the heart’s electrical activity.
• Echocardiography: Uses sound to show locations of heart damage or poor blood flow.
• Cardiac MRI: Uses magnets and radio waves for detailed pictures of a beating heart.
• Multiple gated acquisition (MUGA): Cameras track small amounts of a radioactive substance in the blood to measure the heart’s pumping action.

Your doctor will put a soft, hollow tube called a catheter into a large blood vessel in your arm or upper thigh that goes to your heart. They may put a special dye through the tube that shows up on X-rays (angiography). This shows if you have narrowed or blocked coronary arteries. They may also check how your heart responds to certain drugs or electrical signals. They may use the catheter to open your blocked arteries (angioplasty).

An automated defibrillator goes under your skin. It sends electric shocks to your heart whenever it senses irregular heartbeats. It’s different from a pacemaker, which prevents slow heart beats. You may need both to regulate your heart’s rhythm. 

You may need one if you’ve had:

• Serious heart disease
• Cardiac arrest or a heart attack
• Repeat arrhythmias or other electrical problems with your heart
• Certain neuromuscular disorders

You can’t always prevent cardiac arrest, but you can make some lifestyle changes to lower your chances of heart disease or serious events like a heart attack. For starters, it’s best to eat a balanced diet low in added sugar, salt, and processed foods. Eat plenty of vegetables, fruits, healthy fats, whole grains, and lean meats. Your doctor or a dietitian may suggest the Dietary Approach to Stop Hypertension (DASH) eating plan.

You should also:

• Get regular physical activity: At least 150 minutes of exercise a week.
• Learn relaxation techniques to manage stress.
• Quit smoking to lower your odds of heart disease and make heart attack recovery easier.
• Maintain a healthy weight. Obesity may play a larger role in heart disease if you’re 34 or younger.
• Manage health problems. Unmanaged high blood pressure, high cholesterol, and diabetes can all hurt your heart.

Cardiac arrest may have an intense effect on your emotions. You might have anxiety, depression, or posttraumatic stress disorder (PTSD) after you leave the hospital. Later on, you could feel afraid, lonely, or moody. Tell your doctor if you’re having emotional challenges. They can refer you to a mental health professional. You can also lean on your spiritual counselor or your friends and family.