Cardiovascular Health

Can drinking wine provide benefits for divers?

Historically, alcohol was used to treat bends in Greek sponge divers. In the late 1980s attempts to verify the possible beneficial effects of ethanol on prevention of DCS led to prevailing opinions that there was no proven benefit and that divers should not drink and dive. On the other hand, the assumption that wine drinking has beneficial effects on general health is still propagated.

wine_shutterstock_85339912The so called “French paradox” fueled a search for possible healthful components in wine that, as some researchers posted, protect French people from heart disease despite their fat rich diet and high blood cholesterol levels. Tannins and phenolics, a large group of substances that together make up to 0.1% of wine mass and determine the color and the taste of wine, were identified as beneficial substances. The most intriguing and studied phenolic is resveratrol which is now also sold as a dietary supplement.

Studies of resveratrol in vitro (on cellular cultures or in various models of biochemical systems) have shown anti-oxidant and other effects that with basic biological processes may provide protection against aging, various diseases and death. Further animal studies appeared to confirm beneficial effects. Some of the suspected mechanisms involving resveratrol included functions of endothelial cells (inner lining of blood vessels) and platelets which are also affected in diving. If resveratrol could prevent endothelial cell dysfunction and platelet aggregation, it may help to avoid decompression sickness. Recent resveratrol studies claimed several additional health benefits that could be appealing to divers.

The first claim is that resveratrol has beneficial effects on
skeletal and cardiac muscle functions similar to what is seen with endurance exercise training.1  Wouldn’t it be nice to work on your fitness by relaxing and sipping wine after a long workday rather than going to the gym and sweating?

The second claim is that resveratrol improves brain perfusion and provides neuroprotection2, both of which may be helpful in reducing risk of decompression sickness. Why not drink wine before or after diving?

Unfortunately, there is only one problem with all these studies; the amount of resveratrolDelicious  portion of  fresh salmon fillet  with aromatic herbs, used is equivalent to drinking 50 to 3000 liters of wine per day. It is far more than is needed to get drunk. It’s enough to dive in. Thus, drinking red wine does not seem to be a practical prophylaxis of decompression sickness.

But don’t despair. Even French Paradox is not due to wine drinking as was believed forty years ago. Most population studies indicate that health and longevity may be associated with overall diet. The benefits of French diets appear to come from plenty of fresh vegetables, moderate caloric intake and physical activity rather than just from wine. The French diet has a lot in common with the so called Mediterranean Diet which is widely considered most favorable. In fact, in 2010 it was acknowledged by UNESCO as an Intangible Cultural Heritage of Humanity. (http://www.unesco.org/culture/ich/en/RL/mediterranean-diet-00884)

This story illustrates a common wisdom that there is no one single dietary supplement that could provide what mortals want. To stay healthy and fit for diving, adopt a healthy diet3 and, if you drink wine, limit yourself to one glass with your meal. More importantly, do not drink before the dive.

For quick orientation about healthy meal check MyPlate

http://health.gov/dietaryguidelines/2015/guidelines/chapter-3/strategies-for-action/#callout-myplate

 

References

  1. Dolinsky VW, Kelvin E. Jones EJ, Robinder S. Sidhu SS, Mark Haykowsky M, Michael P. Czubryt MP, Tessa Gordon T, and Jason Dyck   Improvements in skeletal muscle strength and cardiac function induced by resveratrol during exercise training contribute to enhanced exercise performance in rats. J Physiol 590.11 (2012) pp 2783–2799
  2. Otto MA. Resveratrol improves cerebral perfusion in type 2 diabetes. Clinical Endocrinology News Digital Network. January 17, 2016 http://www.clinicalendocrinologynews.com/specialty-focus/diabetes/single-article-page/wdc-resveratrol-improves-cerebral-perfusion-in-type-2-diabetes/1fe1ba3439a5ae9dc24b003d21793512.html
  3. US Department of Health and Human Services and US Department of Agriculture 2005 – 2020 Dietary Guidelines for Americans. 8th December 2015. Available at health.gov/dietaryguidelines/2015/guidelines/.

Can a coronary calcium scan improve the prediction of heart attacks in older divers?

In the July 2015 issue of Undercurrent, an article titled “A better heart-check tool than a stress test?” discusses the possible benefits of a coronary calcium scan for older divers to reduce the risk of experiencing a heart attack while diving.1 This article is a follow-up to a May 2015 Undercurrent report about an overweight 65-year-old diver who died shortly into his dive while on a dive trip.2 That article, which considered preventive options such as a stress test, also presented views from Dr. Alfred Bove and DAN’s Dr. Petar Denoble and Dr. James Chimiak, who agreed with the American College of Physicians (ACP) guidelines that recommend a graded and individualized approach to preventive testing and diagnostics.

Another physician suggests in the July 2015 article, however, that older divers should have a coronary calcium scan, which he claims may provide information that will help them avoid a heart attack on their dive trips. Many walk-in clinics offer the test at a low price. “A coronary calcium scan can tell you years before a positive stress test that you are headed in that direction [of significant coronary disease] so that you can do some kind of intervention,” he said. While the statement has merit, it may be misleading in this context.

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PFO Closure and Susceptibility to DCS

PFO_HeartArt_Final2In a recent paper published in the Journal of the American College of Cardiology, Jakub Honek and coauthors presented their findings concerning diving with PFO (patent foramen ovale) closures.

To examine PFO closure and susceptibility to DCS, the researchers focused their study on two groups: 19 divers who had large persistent PFOs and 15 divers who had their PFO surgically closed.

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SPUMS 2014 Consensus Consideration

02A132RXIt is the last day of the official SPUMS 2014 Scientific Conference, and recommendations regarding patent foramen ovale (PFO) and diving have been discussed.  The following is proposed for consideration as the SPUMS position (final paper not yet edited):

  1. Routine screening for PFO in divers is not indicated.
  2. PFO test should be considered in case of:
  • History of decompression sickness (DCS) with cerebral, spinal, inner ear or skin manifestations
  • Any history of migraine with aura
  • History of cryptogenic stroke
  • Family history of PFO or atrial septal defect (ASD) in first-degree relatives

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PFO and Inner Ear DCS

Does the selective vulnerability of the inner ear to DCS help explain the disconnect between a prevalent risk factor and a rare disease?

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In his presentation at SPUMS 2014, Dr. Simon Mitchell has summarized the work he and Dr. David Doolette have done regarding the pathophysiology of inner ear decompression sickness (IEDCS) as well as some recent publications from other authors.

Mitchell addressed the reservations some experts have when it comes to the causal relationship of patent foramen ovale (PFO) and decompression sickness (DCS). Some experts say there is a disconnect; PFO must be present in many divers (one quarter), but DCS occurs only in few. Wilmshurst responds to this disconnect asserting that only divers with a large PFO are at risk and this is generally in line with the DCS statistics.

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PFO: Is It Time to Change the Course?

wooden pointerPresentations at SPUMS continue…

Peter Wilmshurst’s series of cases shows that 79% of all skin DCS have PFO, 10% lung disease and only remaining cases occur in divers with closed PFO due to severe dive exposure. Similar statistics were provided for inner ear DCS and neurological DCS. Other authors dispute association of PFO with spinal form of DCS  and say only cerebral DCS appears to be associated. Nevertheless, a large number of DCS cases could be avoided if the diver was aware of PFO and exercised caution.

How safe is the option of transcatheter closure?

Mark Turner, another cardiologist from the United Kingdom, provided a detailed presentation of the procedure, pitfalls and outcomes. The overall outcome: Successful with very low rate of adverse events.

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Review of PFO and Diving at SPUMS Meeting 2014

PFO_HeartArt_Final2At the 43rd Annual Scientific Meeting of South Pacific Underwater Medical Society going on May 18 – 25, 2014, a key theme is PFO and diving. The keynote speaker is Dr. Peter Wilmshurst, the cardiologist and diving physician who first described the association between PFO and decompression sickness in 1986. Here, he presented his findings in several hundred cases of DCS.  His insight into this problem is most valuable and we are looking forward to the publication of a synthesis of his findings.

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