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Spoiler alert: Stop reading if you haven’t watched the show and don’t want to find out details of the plot.
It’s revealed Jack Pearson suffered a cardiac arrest in the hospital after helping his family escape their burning home, with a doctor telling his stunned wife that smoke inhalation put stress on his lungs and heart.
Here’s what you need to know about the conditions mentioned on the show:
In a cardiac arrest, the heart’s electrical system fails, causing the organ to suddenly stop beating and unable to pump blood to the brain, lungs and other parts of the body, according to the American Heart Association. A person becomes unconscious within seconds, no longer has a pulse and stops breathing. Starved for oxygen, brain cells start dying quickly and many people who do survive a cardiac arrest end up with brain damage.
The odds of surviving are slim: Four out of five cardiac arrests happen in the home, and more than 90 percent of the victims die before reaching the hospital, according to an Institute of Medicine report.
A cardiac arrest is distinct from a heart attack, where blood flow to the heart is blocked, but the two conditions are linked.
When a sudden cardiac arrest occurs, a heart attack is a common cause, although most heart attacks don't lead to a sudden cardiac arrest, the American Heart Association explains.
Some of the characters in the “This Is Us” episode call what happened to Jack a “widowmaker,” which references a type of heart attack that involves major blockage in the left anterior descending (LAD) artery, one of three arteries that supply blood flow to the heart, the Cleveland Clinic notes.
This particular type of heart attack has a low survival rate, thus earning it the grim nickname. "The Biggest Loser" trainer Bob Harper suffered a "widowmaker" last year after a workout: "My heart stopped. Not to be dramatic, but I was dead. I was on that ground dead," he said. Harper was revived after bystanders performed CPR and administered a defibrillator.
Don’t be misled by the nickname's gender reference: Women can also suffer a “widowmaker” heart attack.
Smoke inhalation risks
When it comes to smoke, the biggest health threat is from fine particles, which can penetrate deep into your lungs and cause a variety of health problems, according to the U.S. Environmental Protection Agency. Fine particles in wood smoke can trigger heart attacks, stroke, irregular heart rhythms, and heart failure, especially in people who are already at risk for these conditions, it notes.
People who exercise or do strenuous activity during the smoky conditions — such as running into a burning house to save their family, "This Is Us"-style — may be particularly affected because they’re breathing hard and fast, taking in more of the fine particles.
Role of alcohol abuse
Jack’s wife mentions he’s a recovering alcoholic, which could play a role in heart health. Drinking more alcohol than the recommended amount — one to two drinks per day for men, and one drink per day for women — increases the risk of high blood pressure, obesity and stroke, the American Heart Association notes.
Long-term heavy drinking weakens the heart muscle, leading to alcoholic cardiomyopathy, where the organ can’t pump blood efficiently, according to the National Institutes of Health. It can also disturb the heart’s internal pacemaker system, causing it to beat too rapidly or irregularly.