What is a congenital heart defect?

The probable cause of Bronny James' sudden cardiac arrest last month was revealed on Friday night.

A James family spokesperson released a statement saying a congenital heart defect likely led to the USC basketball freshman collapsing during a July 24 practice at the Trojans' Galen Center.

The diagnosis was made after an initial evaluation at Cedars-Sinai Medical Center in Los Angeles and follow-up visits to the Mayo Clinic and New Jersey's Atlantic Health/Morristown Medical Center.

The defect is "anatomically and functionally significant" but one that "can and will be treated," the statement said. The James family is confident Bronny will make a full recovery and return to the court in the "very near future."

So what exactly is a congenital heart defect? Here's what to know.

What is the definition of a congenital heart defect?

A congenital heart defect (CHD) is the most common type of birth defect and can "affect the structure of a baby’s heart and the way it works," according to the CDC. CHDs can range from mild cases like a small hole in the heart to severe ones like missing or poorly formed parts of the heart, per the CDC.

CHDs are present at birth and can even be detected as early as during pregnancy, though there are instances where they go undiagnosed until adulthood.

There are an estimated two million-plus individuals in the United States living with CHD, according to the CDC.

What are the different types of congenital heart defects?

There are several different types of CHDs, with some being classified as critical. About 25 percent of babies born with a heart defect have a critical CHD, which requires surgery or other procedures within the first year of life, according to the CDC.

Here are the different types of CHDs that the Mayo Clinic lists:

• Atrial septal defect (ASD)
• Atrioventricular canal defect
• Coarctation of the aorta
• Congenital heart defects in children
• Congenital mitral valve anomalies
• Double-outlet right ventricle
• Ebstein anomaly
• Eisenmenger syndrome
• Hypoplastic left heart syndrome
• Long QT syndrome
• Partial anomalous pulmonary venous return
• Patent ductus arteriosus (PDA)
• Patent foramen ovale
• Pulmonary atresia
• Pulmonary atresia with intact ventricular septum
• Pulmonary atresia with ventricular septal defect
• Pulmonary valve stenosis
• Tetralogy of Fallot
• Total anomalous pulmonary venous return (TAPVR)
• Transposition of the great arteries
• Tricuspid atresia
• Truncus arteriosus
• Vascular rings
• Ventricular septal defect (VSD)
• Wolff-Parkinson-White (WPW) syndrome

It has not been revealed which type of CHD James was diagnosed with.

What causes congenital heart defects?

The causes of most CHDs are unknown, though some are inherited.

What are the symptoms of congenital heart defects?

The Mayo Clinic says common CHD symptoms in adults include:

• Irregular heart rhythms (arrhythmias)
• Blue skin, lips and fingernails (cyanosis)
• Shortness of breath
• Feeling tired very quickly with activity
• Swelling of body tissue or organs (edema)

What is the treatment for congenital heart defects?

Treatment for adults with CHDs can include regular checkups, medications or surgeries, according to the Mayo Clinic.

There are complications that can arise even well after a CHD has been treated, such as irregular heartbeats (arrhythmias), heart infection (endocarditis), stroke, high blood pressure in the lung arteries (pulmonary hypertension) and heart failure, according to the Mayo Clinic.

What athletes have congenital heart defects?

James isn't the first notable athlete with a CHD. Former USWNT midfielder/forward Lauren Holiday underwent open-heart surgery at the age of 3 to repair an atrial septal defect, while legendary snowboarder/skateboarder Shaun White had two open-heart surgeries before he turned 1 to treat tetralogy of fallot.

In 2005, New England Patriots three-time Super Bowl champion linebacker Tedy Bruschi suffered a stroke caused by a previously undiagnosed patent foramen ovale. Bruschi underwent a procedure to repair the defect and was back on the field later that same year.