Atrial Septal Defects
What's an atrial septal defect and how does it affect diving?
An atrial septal defect (ASD) results from the incomplete closing of the wall that separates the right and left atria (the two upper chambers of the heart) during embryonic development. This is not an uncommon phenomenon in the general population, and, if the hole is small enough, the average person will experience minimal physiologic consequences. Women are affected more commonly than men.
Surgical correction of the defect may be undertaken, especially if the person is experiencing symptoms secondary to blood flowing from the normally higher pressure left atrium to the right atrium. Early in life, symptoms may be few, but over a period of years, complications, such as abnormal heart beats and shunting (bypassing) of blood from left to right may occur.
On examination, the person with an ASD may have a significant murmur.
Fitness and Diving Issue: While the normal pressures in the chambers of the heart favor blood flowing from left to right through an ASD and VSD, periods in which this flow is reversed can occur, particularly for ASD. Although individual variations exist, Doppler studies have shown that most divers will have venous bubbles after a dive of significant depth and bottom time. These usually pose no significant threat, and the diver remains symptom-free.
Having a defect that allows bubbles to cross from the right side of the heart to the left is a whole different matter, however: once in the left side of the heart, bubbles may then be transported through the arteries to areas of the body where they can do some harm (e.g., to the brain, kidneys, and spinal cord). Several studies have demonstrated that the number of ASD’s (and other defects in the wall separating the right and left sides of the heart) in divers treated for decompression illness was higher than expected, compared to the general population.
Someone with an ASD or VSD who wants to take up scuba diving should be discouraged from doing so. The diver with a known ASD or VSD should know what the implications are on their chances of developing decompression illness make an educated decision whether to continue diving or not. Individuals with a VSD, where the shunt is small and runs uniformly from left to right, as determined by an echocardiogram, may be able to dive if it is determined to be safe by a physician knowledgeable in diving medicine.
Surgical correction of the defect may be undertaken, especially if the person is experiencing symptoms secondary to blood flowing from the normally higher pressure left atrium to the right atrium. Early in life, symptoms may be few, but over a period of years, complications, such as abnormal heart beats and shunting (bypassing) of blood from left to right may occur.
On examination, the person with an ASD may have a significant murmur.
Fitness and Diving Issue: While the normal pressures in the chambers of the heart favor blood flowing from left to right through an ASD and VSD, periods in which this flow is reversed can occur, particularly for ASD. Although individual variations exist, Doppler studies have shown that most divers will have venous bubbles after a dive of significant depth and bottom time. These usually pose no significant threat, and the diver remains symptom-free.
Having a defect that allows bubbles to cross from the right side of the heart to the left is a whole different matter, however: once in the left side of the heart, bubbles may then be transported through the arteries to areas of the body where they can do some harm (e.g., to the brain, kidneys, and spinal cord). Several studies have demonstrated that the number of ASD’s (and other defects in the wall separating the right and left sides of the heart) in divers treated for decompression illness was higher than expected, compared to the general population.
Someone with an ASD or VSD who wants to take up scuba diving should be discouraged from doing so. The diver with a known ASD or VSD should know what the implications are on their chances of developing decompression illness make an educated decision whether to continue diving or not. Individuals with a VSD, where the shunt is small and runs uniformly from left to right, as determined by an echocardiogram, may be able to dive if it is determined to be safe by a physician knowledgeable in diving medicine.
Posted in Dive Safety FAQ
Categories
2024
February
March
April
May
October
My name is Rosanne… DAN was there for me?My name is Pam… DAN was there for me?My name is Nadia… DAN was there for me?My name is Morgan… DAN was there for me?My name is Mark… DAN was there for me?My name is Julika… DAN was there for me?My name is James Lewis… DAN was there for me?My name is Jack… DAN was there for me?My name is Mrs. Du Toit… DAN was there for me?My name is Sean… DAN was there for me?My name is Clayton… DAN was there for me?My name is Claire… DAN was there for me?My name is Lauren… DAN was there for me?My name is Amos… DAN was there for me?My name is Kelly… DAN was there for me?Get to Know DAN Instructor: Mauro JijeGet to know DAN Instructor: JP BarnardGet to know DAN Instructor: Sinda da GraçaGet to know DAN instructor Trainer: Christo van JaarsveldGet to know DAN instructor: Gregory DriesselGet to Know DAN Instructor: Beto Vambiane
November
Get to know DAN Instructor: Dylan BowlesGet to know DAN instructor: Ryan CapazorioGet to know DAN Instructor: Tyrone LubbeGet to know DAN Instructor Trainer: Christo van JaarsveldGet to know DAN Instructor: Caitlyn MonahanSafety AngelsDiving With A PFODiving Anilao with Adam SokolskiScience Saves SharksUnderwater NavigationUnderstanding Dive Equipment Regulations
2023
January
March
Terrific Freedive ModeKaboom!....The Big Oxygen Safety IssueScuba Nudi ClothingThe Benefits of Being BaldDive into Freedive InstructionCape Marine Research and Diver DevelopmentThe Inhaca Ocean Alliance.“LIGHTS, Film, Action!”Demo DiversSpecial Forces DiverWhat Dive Computers Don\'t Know | PART 2Toughing It Out Is Dangerous
April
July
August
September
Mismatched Scuba Valves to Cylinder OutletsUnderwater Crime Scene InvestigatorsDive Boat Etiquette – From Yachts to rubber ducksTravel Smarter: Personal Safety While TravelingLiability in ContextLearning from Success. Learning from MistakeDive in the Fast Lane with DPVsKwaZulu Natal shipwrecks: The ProduceAvoid Diving With EarplugsThe Parting Shot
No Comments