Dear Doctor: Our mom is 66 years old and has always been healthy. She was diagnosed with atrial fibrillation during her last physical. She says she feels fine, so she hasn’t followed up with her doctor. What can happen if she doesn’t get treatment?

Dear Reader: Atrial fibrillation is a common heart rhythm disorder, or arrhythmia, that affects anywhere from 2.5 million to 6 million people living in the United States. Also referred to as AFib or AF, the condition causes a rapid and irregular heartbeat. People living with AFib have an increased risk of stroke, heart failure and other heart-related complications. The good news is that there are several effective treatment avenues for the condition. Without treatment, however, the symptoms of AFib often get worse.

The condition gets its name from an electrical malfunction in the upper chambers of the heart, known as atria, which pump blood into the ventricles, the two lower chambers of the heart. It occurs due to a glitch in the sinus node, a cluster of specialized cells in the upper wall of the right atrium, which act as the heart's natural pacemaker. Instead of producing a steady, rhythmic contraction, the atria quiver, or fibrillate. The result is a disorganized heartbeat, rapid and irregular, which interferes with optimal blood flow. It often causes blood to pool in the left atrium, which can lead to the formation of blood clots. If a blood clot breaks free, it can circulate and block blood flow to other parts of the body. A blood clot that travels to the brain can cause a stroke.

Many people with AFib -- and it sounds as though your mother may be one of them -- don’t experience any noticeable symptoms. Those who do will feel a jittery, racing heartbeat; the sensation of a skipped heartbeat followed by a “thump” within the chest; exhaustion; shortness of breath; dizziness; chest pain or pressure; or unusual fatigue during exertion. The condition runs the gamut from mild to severe. Occasional episodes, known as paroxysmal AFib, last from a few seconds to a few hours, and the heart recovers on its own. AFib that requires medication or an electric shock to return to normal rhythm is labeled as persistent. Permanent AFib is when normal heart rhythm cannot be restored.

Treatment depends on which specific type of AFib a person has, as well as on any additional medical issues that may be present. In all types of AFib, the dual goals are to restore normal heart rate and to prevent blood clots. Medications such as digoxin, beta blockers and calcium channel blockers may be used to restore heart rate. Blood thinners, including Warfarin and newer anticoagulants, are often prescribed to prevent stroke. If medications don’t work, procedures to inactivate the sinus node cells causing the arrhythmia may be used. In some cases, a pacemaker is the best option.

Even though your mother can’t feel the symptoms of her AFib, the condition is dangerous when it goes untreated. We strongly urge her to see a cardiologist and begin a potentially lifesaving therapy.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10880 Wilshire Blvd., Suite 1450, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: Our city has asked us to wear a face mask when we leave the house. Needless to say, my wife and I have never done this before. Does our 5-year-old son need a mask, too? Any guidance or how-tos would be greatly appreciated.

Dear Reader: Your local government is following the updated recommendation from the Centers for Disease Control and Prevention, which urges people to wear a cloth covering over their nose and mouth whenever they go out in public. These face coverings don’t serve as protection from becoming infected with the virus. Rather, they are a physical barrier that may prevent someone who is infected from spreading it. This is particularly valuable in cases where someone is infected but has no symptoms.

This is very important, so imagine our voices as stern and serious when you reach the uppercase words in the next sentence. A face mask should only be used IN ADDITION TO and never INSTEAD OF the other important steps we’re all taking right now. These include social distancing, frequent and thorough hand-washing, not touching your face, and cleaning high-touch surfaces such as door handles, light switches, phones, eyeglasses and sunglasses. (And don’t forget about the handles of your car doors and your steering wheel.)

Face coverings should be snug but comfortable, fit against the sides of the face and beneath the chin, and allow for unrestricted breathing. They can be secured by ear loops or ties and should include multiple layers of fabric. Make sure the masks you choose can be washed and machine dried without damaging the mask or changing its shape.

When putting on a mask, start with clean hands. Always hold it by the strings or straps, not by the mask itself. Place it over your nose and mouth and adjust the straps so that you have a snug but comfortable fit. If your mask has a bendable metal clip over the bridge of the nose, gently adjust it to the contour of your face. If you wear glasses, put them on after the mask. It’s important that any facial covering you use, even if it’s just a bandanna, completely covers both your nose and mouth, and also the bottom of your chin. It’s helpful to practice at home to get optimal fit and comfort.

Before you remove your mask, clean your hands. Again, you’ll be handling it only by the ties or straps. If it’s disposable, throw it away. If it’s reusable, wash it with soap in hot water and machine dry thoroughly on medium or high heat. And please, never use medical-grade N95 masks. These are in short supply and are desperately needed to keep frontline workers safe.

Yes, your son should wear a mask in public as well. The CDC recommends everyone 2 years of age and older wear a mask that covers their nose and mouth. Due to the risk of suffocation, face coverings should not be used on anyone younger than 2. We hope this helps, and that you and your family stay vigilant, safe and healthy.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10880 Wilshire Blvd., Suite 1450, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Hello again, dear readers, and thank you for joining us for this month’s letters column. It’s a difficult and challenging time, and we’re more grateful than ever for the community that has sprung up in response to Ask the Doctors.

-- A reader from Ohio, Illinois, who is her dad’s caregiver, asked for guidance on expiration dates on food items. “He buys more food than he needs, and it stays in the refrigerator well past the ‘sell-by’ date,” she wrote. “I’ve brought it up several times, but we just argue because he thinks it’s OK.”

You’re correct that it’s important to be vigilant about food freshness and safety. Older adults are at increased risk of hospitalization, and even death, due to food-borne illness. You mentioned your father’s handling of prepared foods, like baked chicken, as well as staples like eggs and bacon. It’s helpful to know that the sell-by dates on packaged foods refer to food quality rather than food safety. Eggs that remain refrigerated are safe to use for up to three weeks beyond the sell-by date. A package of bacon can be kept refrigerated for up to a week beyond the sell-by date. With prepared foods, however, the window becomes much smaller. When refrigerated properly, cooked chicken will last for three to four days. After that, it’s not safe and should be thrown away.

-- A reader from Omaha, Nebraska, wondered about health benefits attributed to a few teaspoonfuls of apple cider vinegar per day. It’s an age-old folk remedy, and while many of the claims are far-fetched -- no, you can’t replace blood pressure meds with apple cider vinegar -- there is some evidence that it can be helpful. For instance, studies have shown that apple cider vinegar may play a modest role in control of blood sugar. It may also aid in weight loss by suppressing appetite. However, apple cider vinegar is an acid, which can erode tooth enamel. Be sure to always rinse your mouth thoroughly after having any.

-- A reader from Dallas, Pennsylvania, sent us an ingredient label from his favorite food, a prepared meal of Salisbury steak with macaroni and cheese. He asks if it contains dangerous ingredients. Although the ingredients themselves are benign, the nutritional information has some bad news. One serving contains 1,110 milligrams of sodium, which is almost half the recommended daily value. The saturated fat content is also a bit high, at 30%. Rather than a daily meal, it would be wise to make this a weekly treat. Instead, add some lean meat, fresh vegetables, whole grains and healthy oils to your diet. Your body -- and your family doctor -- will thank you.

-- After reading a column about improving indoor air quality during a wildfire, a reader from Tulsa, Oklahoma, was baffled by the advice to refrain from dusting or vacuuming. “How do you keep the house clean?” he wrote. “Isn’t it impossible?” Those tasks kick up significant particulates, so it’s wise to defer them when air quality is bad, as during a wildfire. Once the outdoor air has cleared, it’s safe to dust and vacuum.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10880 Wilshire Blvd., Suite 1450, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)