Murmur vs. PFO

[Wendy]

What is the difference between a heart murmur and a PFO? And do each affect a diver?

Thanks!

 

[scubabamatxn]

I'm not a doctor, but here is the 'short version'. I'm sure someone else will add. PFO is a Patent Foramen Ovale. As fetuses, we all had a hole between the two heart atria--this allowed us to breath without developed lungs. After birth, the hole is supposed to close. Unfortunately, for a surprising number of people, sometimes the hole does not close completely. Why is this a problem for divers ? Simply stated, some bubbles in the bloodstream can 'cross-over' in the heart and go directly to the brain-- resulting in stroke or death potentially. There is a good article about this in the current "Alert Diver' magazine. A 'murmur' is the result of a heart valve working less than normally. The impact depends on the severity, I supose. It can get worse over time, and certainly needs to be monitored. Hope this'short version' helps.

 

[jbd]

I'm not a doctor, but here is the 'short version'. I'm sure someone else will add. PFO is a Patent Foramen Ovale. As fetuses, we all had a hole between the two heart atria--this allowed us to breath without developed lungs. After birth, the hole is supposed to close. Unfortunately, for a surprising number of people, sometimes the hole does not close completely. Why is this a problem for divers ? Simply stated, some bubbles in the bloodstream can 'cross-over' in the heart and go directly to the brain-- resulting in stroke or death potentially. There is a good article about this in the current "Alert Diver' magazine. A 'murmur' is the result of a heart valve working less than normally. The impact depends on the severity, I supose. It can get worse over time, and certainly needs to be monitored. Hope this'short version' helps.

Very good short version. I will add that murmurs are sounds made by blood flow through valves that have not closed completely. With good skills using a stethoscope you can tell which valves are affected.

Although I have never knowingly listened to someones heart that with a PFO I would guess that it could also be a cause of a murmur. Maybe DocVikingo or one of the others will be along to enlighten us a bit more.

 

[GoBlue!]

PFO is as described. I've listened to many patients with known PFOs, and have not detected murmurs. The flow through a PFO is normally so low that it'd be tough to hear. The larger atrial septal defects, however, can be picked up quite readily in most cases.

A heart murmur is really just an indication of turbulent blood flow. A murmur does not necessarily indicate a "leaky valve," although that could certainly be one cause. Certain people simply have anatomy that causes a bit more turbulence, and this is of no clinical significance. Any hyperdynamic state (e.g., pregnancy) in which the cardiac output is markedly increased can cause a murmur, but this is also entirely normal. In fact, I start to wonder if my ears are plugged up if I listen to a pregnant woman's heart who does NOT have a murmur!

Depending on the location, quality, and how the murmur changes with certain maneuvers, one can determine quite accurately whether the murmur is anything to worry about, what valves (if any) are likely affected, etc.

As for implications for diving, a heart murmur could have no significance (if a typical, benign "flow murmur," say of a thin-chest-walled young person) to a severe impact (e.g., bicuspid aortic valve with aortic stenosis & regurgitation). If the physician is concerned about the cause of a murmur, an echocardiogram is used to visualize the valves & bloodflow.

Jim

 

[jbd]

PFO is as described. I've listened to many patients with known PFOs, and have not detected murmurs. The flow through a PFO is normally so low that it'd be tough to hear. The larger atrial septal defects, however, can be picked up quite readily in most cases.

A heart murmur is really just an indication of turbulent blood flow. A murmur does not necessarily indicate a "leaky valve," although that could certainly be one cause. Certain people simply have anatomy that causes a bit more turbulence, and this is of no clinical significance. Any hyperdynamic state (e.g., pregnancy) in which the cardiac output is markedly increased can cause a murmur, but this is also entirely normal. In fact, I start to wonder if my ears are plugged up if I listen to a pregnant woman's heart who does NOT have a murmur!

Depending on the location, quality, and how the murmur changes with certain maneuvers, one can determine quite accurately whether the murmur is anything to worry about, what valves (if any) are likely affected, etc.

As for implications for diving, a heart murmur could have no significance (if a typical, benign "flow murmur," say of a thin-chest-walled young person) to a severe impact (e.g., bicuspid aortic valve with aortic stenosis & regurgitation). If the physician is concerned about the cause of a murmur, an echocardiogram is used to visualize the valves & bloodflow.

Jim

Didn't know that about pregnant women. Thanks for the added info.

 

[wpscortland]

PFO is as described. I've listened to many patients with known PFOs, and have not detected murmurs. The flow through a PFO is normally so low that it'd be tough to hear. The larger atrial septal defects, however, can be picked up quite readily in most cases.

A heart murmur is really just an indication of turbulent blood flow. A murmur does not necessarily indicate a "leaky valve," although that could certainly be one cause. Certain people simply have anatomy that causes a bit more turbulence, and this is of no clinical significance. Any hyperdynamic state (e.g., pregnancy) in which the cardiac output is markedly increased can cause a murmur, but this is also entirely normal. In fact, I start to wonder if my ears are plugged up if I listen to a pregnant woman's heart who does NOT have a murmur!

Depending on the location, quality, and how the murmur changes with certain maneuvers, one can determine quite accurately whether the murmur is anything to worry about, what valves (if any) are likely affected, etc.

As for implications for diving, a heart murmur could have no significance (if a typical, benign "flow murmur," say of a thin-chest-walled young person) to a severe impact (e.g., bicuspid aortic valve with aortic stenosis & regurgitation). If the physician is concerned about the cause of a murmur, an echocardiogram is used to visualize the valves & bloodflow.

Jim

I've heard a lot about PFO recently, but no real advice. I heard of one dive club that has all its members tested for PFO?? Should a diver be tested for this? What test would be done? And what would a diver do differently if they confirmed they had a PFO. I am going to post this as a new thread, but wanted your input since you explained it to some extent already.

 

[GoBlue!]

I see this has already popped up as a new thread, but I'll answer a bit here. My personal opinion is that I don't believe that every diver should be forced to undergo an echocardiogram to rule out a PFO prior to certification. While a transthoracic echocardiogram (not the gold standard for PFO, but would be the best non-invasive screening test) will not harm you, if we take the number of new divers each year & multiply that by the cost/echo & compound that with the uncertainty surrounding PFO & DCI risk, I think the cost:benefit analysis just doesn't support general screening yet.

If a diver needs to have an echocardiogram for another unrelated reason anyway, I think it'd be reasonable to ask their physician to also do the "contrast" portion (injecting agitated saline, essentially) to evaluate for possible PFO. This information could then be discussed in a conversation with a dive physician to discuss DCI-risk for an individual patient.

PFOs are quite common in the overall population. They are, of course, of different sizes which may be associated with different relative risks of DCI. Given the fact that the DCI incidence is so extraordinarily low, common sense dictates that while a PFO may increase the risk of DCI, the absolute risk will still be very, very low. Perhaps some of those on the forum who are further trained in dive medicine can comment.

I should say that anyone who has had stroke-like symptoms or other symptoms of arterial embolization of clot thought to originate from the venous circulation should definitely be evaluated for PFO, but should not be diving anyway!

(This is an opinion & for educational use only, not considered medical advice nor a doctor-patient relationship.)

Jim