Q:Thomas McGill had a follow-up question regarding a feature article I did a few months ago called “The Telltale Heart” (April 2010). Could you expand on some information on diving with pacemakers for me? The article states, in part, ‘there is no reason why a pacemaker should automatically disqualify anyone from recreational diving.’ I and the pacemaker manufacturers seem to agree with this. The article goes on, ‘the real issue is why the patient needs a pacemaker. If the device was implanted solely to correct a problem with the rhythm of the heart, then the candidate can dive. If, however, the heart showed other problems or disease, then the pacemaker candidate should not dive.’ Could you expand on that last sentence for me? My pacemaker was installed because of a slow heart rate. Otherwise, I have no heart difficulties, and I do maintain myself in reasonable physical condition for diving.”
A:Thomas, sorry I wasn’t able to answer your question fully in my earlier feature. The issue is not one of technology but the same concern we have with any medical condition: Might the underlying problem for which the pacemaker was installed affect one’s fitness to participate in scuba diving?
Pacemakers are installed to address abnormalities in the heart’s electrical conduction system. Often, though not always, patients with such abnormalities have some form of cardiac disease as the underlying cause of their abnormality. For example, congenital heart disease, certain valvular heart diseases (aortic stenosis with valvular and AV-ring calcification), cardiomyopathy and coronary heart disease all may be associated with chronic conduction system abnormalities. Any of these conditions can mean that an individual may lack the cardiovascular fitness required to safely participate in diving. In fact, according to the Divers Alert Network, the most common reason for a pacemaker is underlying ischemic heart disease. This is a huge concern in diving because an increasing number of recreational diving fatalities each year are attributable to coronary artery disease. Another complicating factor is that diving often takes place in remote locations far from facilities that provide emergency cardiac care.
In your case, it appears that there was no underlying heart disease, and the pacemaker was installed solely to correct an arrhythmia problem. Assuming you have sufficient exercise tolerance, you are exactly the type of individual who need not be disqualified from diving.
One other issue I also failed to address in the feature involves the pacemaker itself. Any device used while diving must be up to functioning in the underwater environment. Therefore, the pacemaker must be rated to perform at least to a depth of 130 feet (39 m), and must operate satisfactorily during conditions of wide pressure changes, such as during ascent and descent.
Q:Darlene Latamara writes for some direction on what her next step should be concerning training. “I’m a new diver but I really love it. In fact, I’d say I’m addicted. There’s just no other sport, or any leisure activity, that I enjoy as much. So, I want to get as good at it as possible. I’ve made a dozen dives since I was certified, so I’m nowhere near what you’d consider an expert. I loved my Open Water class, and was just about to sign up for an advanced class when one of my dive buddies suggested that I wait. His advice was that I’d get more out of my training if I waited and put a few more dives in my logbook before taking the next step. What do you think, wait or do it now?”
A:This is a debate that has raged among diving instructors for decades and we’re not likely to settle it here. I will give you my opinion, but let’s clarify a few matters. First, the term “advanced diver” can be a bit misleading. Most diver training organizations offer a course designed to introduce divers to advanced diving techniques, and it typically involves only five or six dives. Some programs require a bit more but, bottom line, you’re looking at no more dives than you’ve already amassed. So, the question begs, what’s the point? Or, from a different perspective, does such minimum experience really make you an advanced diver?
Some diving educators say that you really don’t get much out of any advanced training unless you have a reasonable base of experience to build upon. Thus, they encourage divers to defer additional training until their logbooks are a bit meatier. Personally, I don’t buy this.
My concern is over experience, and whether divers gain that experience under the supervision of a trained professional. My view — and it’s backed up by accident data — is that divers are far more likely to get into trouble very early on in their career than even a little bit later. Specifically, 25 dives seems to be the magic number. Get divers to that point, and they’re less likely to be an accident statistic.
So, if the initial phase of a diver’s career is the most potentially dangerous, then that’s when they’d benefit most from competent professional supervision. Furthermore, from a learning perspective, it’s more effective to learn something the right way first, rather than have to unlearn the wrong way and relearn.
There’s also another issue, and it’s one from the student’s perspective, rather than the instructor’s. Regardless of how firmly instructors caution divers that advanced diving doesn’t make them an expert, some students come out of advanced training believing that they’re the second coming of Jacques Cousteau. Leave the ego at home. You’ll never become an expert in 10, 20 or even 100 dives. In fact, researchers have been exploring just what’s required for expert-level performance in many fields, and what’s interesting is that, regardless of the field, it seems to come down to one thing: 10,000 hours of experience doing something. That’s right, 10,000 hours — the equivalent of five years of full-time work. So, don’t fool yourself into believing that any training alone — in any form or from any organization — will make you an expert.
My advice is to take the course, and take it now because now is when you want the guidance of who will, hopefully, be an expert. What designation appears on the c-card is irrelevant.
Q:Richard Werling writes with a concern about the recent devastation in the Gulf. “I’m both angered and sickened to watch the news about BP and the Deepwater Horizon Oil Spill. I can’t imagine how this will turn out, and my heart goes out to those whom this will so dramatically impact. On a more selfish note, I’m also planning to go diving in the Florida Keys in a few months. I keep hearing about how the Loop Current could carry this oil around the Keys, into the Gulf Stream and up the East Coast. So far, it seems that the Keys haven’t been affected, but I wonder what might happen in the near future. What are the effects of oil on coral reefs?”
A:Richard, this event is unprecedented in American history so there’s simply no way that anyone can give you an accurate answer to your question. What I can tell you is that, aside from some studies done after a tanker accident in Panama back in 1986, there hasn’t been a lot of research on the effects of oil on coral reefs. Many laboratory experiments have been conducted — some even indicating that crude oil alone may not be all that bad — but field studies where massive amounts of oil have spilled near coral reefs are, fortunately, pretty rare.
From the studies that have been done, it’s clear that coral reefs that are exposed to crude oil or chemical associates have shown the following list of problems: tissue death; impaired feeding, polyp retraction, sediment clearance ability, larval settlement and mucus production; reduction in calcification rates; gonad damage; larval death and premature extrusion of planulae (larvae); bleaching; and reduction in zooxanthellae primary production. As if this wasn’t bad enough, studies have also shown that the chemical used to disperse the oil can be more harmful to coral reefs than the crude itself.
A more recent experiment in the Keys wasn’t encouraging. Dr. James Cervino, a marine pathologist with the Woods Hole Oceanographic Institution, exposed coral samples to various concentrations of petroleum. He found that the oil interfered with zooxanthellae photosynthesis, making it more difficult for the corals to lay down reef structure. “They are slowly dying,” he said. “Oil would literally wipe out the corals. They are already stressed from temperature. The reefs are just hanging on, and this would tip them over the edge. There would be a mini-collapse of the food chain. If it does come here, there would be nothing we could do to help them.”
However, much may depend on the condition of the oil when it reaches the Keys. According to Dr. John McManus, professor and coral reef specialist at the University of Miami’s Rosenstiel School of Marine and Atmospheric Science, if the oil arrives as tar balls, it could just float over the reefs without causing much damage. The real problem is that an unknown amount of oil is in the form of undersea plumes, which could be more toxic.
As of now, no oil from Deepwater Horizon has reached us. The press reports about tar balls in the Keys have all been shown to come from other sources. Perhaps by the time you read this, we will know more; but with nothing to compare it with, right now no one really knows what will happen.