**EP344: Climate Change and CVD and PFO at PD 2024**
**Dr. Auric Bishop:** Welcome, my name's Dr. Auric Bishop. I'm a cardiologist, an author, and a keynote speaker. I'm CEO of the Healthy Heart Network. I'm all about trying to help people live as well as possible for as long as possible. Heart disease is huge in Australia. Every 20 minutes, someone suffers a heart attack. Most of these could probably have been avoided if only we knew what to do. This podcast is all about helping you understand blood pressure, weight, cholesterol, for better health. If you enjoy this podcast, I would be honoured for a five-star review. You can share it with your family and friends. It may well save someone you love.
**Warwick Bishop:** Hi, Warwick Bishop here, and welcome to my podcast and videocast station. I really do appreciate you tuning in. And look, if you find this podcast valuable, I'd be really grateful if you take a moment to share it with others who you think might get something from it.
Today, I'd like to follow up on the Port Douglas meeting. I've already done one podcast on that, but there was such a lot of information in there that I'd like to share a little bit more. Some of it, obviously, was very technical. Some of it was presentation of cases and discussion. Those discussions were with panels and offered different opinions. It's a stark reminder that often there isn't a single best answer when we're dealing with complicated and difficult individuals with multiple pathologies.
Having said all that, I probably won't go through any of the case presentations, but of course, I took plenty of notes. What I would like to do, though, is share some of the other highlights that you might find interesting. One of our presentations was by Bernard Gersh, who's a very famous cardiologist and a leading world researcher. He shaped some of the practices of today and is also based at the Mayo Clinic, which I mentioned previously. He gave a keynote on climate and health.
This was really interesting, and to be honest, I'd not engaged in this area, either in a great deal of reading or attended any talks about it. But Dr. Gersh really flagged a number of areas where change in climate and environment are likely to have a major impact in the cardiovascular health space in particular. I think we could easily recognise that air pollution, for example, would have a significant impact on lung-related issues, but this was really more directed towards cardiovascular health and the impact of climate change on our individual health.
Well, there are a number of main areas that are likely to be impacted as climate quality deteriorates. One of the first things is going to be the presence of inflammation and coagulability. Well, inflammation, we believe, is now closely linked to the progression of atherosclerosis or plaque within the arteries. Coagulability is an increase in the likelihood of blood clotting when an event occurs within an artery, such as a heart attack. An increase in the likelihood of forming a plaque because you are more likely to clot—you're hypercoagulable—would increase that risk of heart attack and potentially sudden death. So, poor climate is starting to be linked with increases in inflammation and increases in coagulation.
As you might imagine, as temperatures increase, thermoregulation becomes problematic. We know that significant variances in heat, particularly for people with cardiac issues and specifically things like cardiac failure, really are detrimental. So, thermoregulation and increased heat impacting cardiac failure—we see this. In fact, years ago, I used to see when I worked in Darwin the travelers who would head up north during the winter in the south to seek the warm weather in the north, only to be caught out with swollen ankles and shortness of breath as that increased temperature put greater demands on their cardiovascular system.
As you might imagine, if you're exposed to greater heat, you may be then needing to dissipate your own heat, and you'll do that through sweating and perhaps even increased breathing or respiration. Those changes with sweating, increased respiration, and fluid loss—potentially linked up with failure to drink adequate fluid—can lead to electrolyte imbalance. The easiest to imagine are things like climate change, changes in weather, overpopulation, and smog pollution, having an impact on physical and mental stress, and we know that feeds directly into cardiovascular risk.
Dr. Gersh also spoke about small particulate matter, and these are microplastics which are closely linked to cardiovascular outcomes, worsening those outcomes the higher those small particulate matter levels are. They're referred to as micro-nanoplastics, and interestingly, there appears to even be research supporting that these micro-nanoplastics are ending up in our bodies, in the plaque that's developing in our arteries, which is pretty scary, to be honest.
Secondhand smoke is an air pollutant that we are all aware of, and we've probably seen it. Dr. Gersh touched on a community in Pueblo, Colorado, where they actually prevented secondhand smoking by strict community-based regulations, stopping smokers from smoking in areas where non-smokers would be impacted. This was really one of the sentinel studies in this space, and we've seen these changes here in Australia now, where there are designated smoking areas and large areas where smoking is forbidden.
Well, the reason why we've embraced that is this particular study in Pueblo, Colorado, demonstrated somewhere around a 30% to 40% reduction in the risk of myocardial infarction or heart attack over the period of time that they implemented these changes. This is really significant public health initiatives to make super huge differences to the population and communities in terms of the risk of heart attack.
One of the other things that was really striking was that Dr. Gersh spoke about noise pollution. Noise pollution is increasing as populations increase, transport increases, and planes increase. All those things increase. Noise pollution is closely linked to blood pressure, and we know how important blood pressure is in cardiovascular risk. It drives heart attack, stroke, atrial fibrillation, cardiac failure, renal failure, and even drives dementia. So, climate and cardiovascular disease—it really is important.
This was a fascinating talk for me to be listening in on, and it really impacted me how significant these changes around us are and how they're going to really play out with people who have cardiovascular disease.
Look, the other presentation I wanted to touch on briefly was a presentation on the closure of PFO. I'm a little bit personally interested in this. I probably need to describe what a PFO is. Well, in medical speak, it's an abbreviation. Obviously, PFO stands for patent, which means open, foramen, which means hole, and ovale, just meaning round. A patent foramen ovale is something we all have. We need that patent foramen ovale when we're in utero before birth. Because we've got a circulation as an unborn child, we want to direct that circulation to the placenta, not to the lungs.
Because we're in the uterus, we're in amniotic fluid, and sending blood to the lungs makes absolutely no sense. So, we all have, before birth, a hole in our heart that allows blood to pass from the right side of our heart to the left side of our heart by passing the lungs and then heading out, being pumped out to the placenta where it gets oxygenated and carbon dioxide is removed.
Well, when you're born, that hole has a flap on it, and that flap is meant to close. Interestingly, it doesn't close in about 25% of people. It doesn't close properly. That flap still exists, but it can still open. If it can still open, we call that a patent foramen ovale. So, it's very common.
Why is this important? Well, it's important because it can allow blood to go from the right-hand side of the circulation, the venous circulation, if you like, to cross straight into the arterial circulation. One of the situations where this is super important is if you are a diver. If you potentially have bubbles in the blood from diving, from your scuba gear, those bubbles should go to the lungs where they are passed out as you breathe in and out. But if those bubbles cross over through that patent foramen ovale into the circulation, those bubbles can pass out into organs, the brain, and other organs, and give rise to the bends.
So, we see patent foramen ovale as a significant issue in professional divers. Remember, about 25% of the population will have this, which is astounding. One of the other really significant situations where patent foramen ovale is important, and this is the reason I'm particularly interested, is because if a small clot forms in the venous system—for example, you've been sitting for a long period of time, travelling, for example, kicking in the leg or a bump—and a small clot dislodges from somewhere peripheral in the body, comes back to the heart, if that small clot is directed to the lungs, it will be captured by the small capillaries within the lungs, literally filtering the blood going back into the left side of the heart and then being pumped around the arterial system.
So, no large particulate matter would go through the left side of the heart through that arterial system if all blood passes through the lungs, almost acting like a filter. If that small bit of particulate matter—a small clot or thrombus, if you like—comes to the heart and that patent foramen ovale is present, and for some reason the person has coughed or bent or moved or changed the pressures in their chest such that the flap moves, then that small particle, that thrombus or clot, could pass through that foramen into the arterial system and then be pumped around the body with a 25% chance it could go straight to the brain, giving rise to a stroke or an infarct, or lack of blood flow to anywhere else in the body where it lodges.
The reason I'm particularly interested in this is I had exactly an event like that occur in the beginning of April—on the 3rd of April, in fact—at nine o'clock in the morning. One tends to have that blaze into their memory. My foot stopped working properly. Well, after lots of investigation, my arteries were clear everywhere. I didn't have any irregular rhythm in particular, no atrial fibrillation. I then went on and had a study where they literally squirted agitated saline, which has little bubbles in it that show up very well on echocardiography. Those bubbles in that agitated saline were injected into my vein while someone imaged my heart and demonstrated that there was passage of those bubbles from the right side to the left side, not passing through the lungs, confirming in fact I have a patent foramen ovale, and that was the likely cause of the small stroke that I had.
Pleasingly, I've had no ongoing symptoms from that stroke; it's resolved. But I am going to get that patent foramen ovale hole fixed up, and the presentation was one talking about the techniques and some of the associations with that particular procedure, like an increased risk of developing atrial fibrillation, which you might imagine if you're putting something in the atria.
So, climate change and cardiovascular disease, patent foramen ovale, and closure of patent foramen ovale—all the closure devices, which I didn't mention, are implanted from the leg, so it's not major open-heart surgery. It can be done through a vein in the leg. A catheter or a tube is passed up into the heart. That tube easily goes from the right side to the left side. Then, if you like, an umbrella—or the equivalent of an umbrella—opens up on that left side and pulls back to hold the flap in place. Then a second umbrella is opened up in the right atrium, and those two umbrellas, if you like, are then cinched together. Those two discs or umbrellas pulling together act to close that patent foramen ovale, securing the flap so it doesn't move anymore.
Very effective. Pleasingly, a fairly low-risk procedure and with a high degree of success with deployment. Anyway, there you go—environmental change, cardiovascular disease, patent foramen ovale, which I'm particularly interested in myself. Hope you found that interesting.
For now, I'm going to jump. I'm going to wish you the very best. I hope you live as well as possible for as long as possible. Take care and bye for now.
Did you know that coronary artery disease kills one in four people? So most of us are likely to carry some risk or know someone who does. If you're interested in finding out more about how to evaluate that risk, check out www.virtualheartcheck.com.au. It'll give you information about risk and what else can be done to be even more precise.
