...and if Lt ventricular hypertrophy (cardiomyopathy)is a normal result from being a highly trained distance runner, why is it postulated as a cause of sudden cardiac death (e.g. Micah True, Ryan Shay, etc.). How can the same condition be both normal and dangerous?
I'm not an MD yet but I can weigh in here:There's a big difference between left ventricular hypertrophy and hypertrophic cardiomyopathy.Hypertrophic cardiomyopathy is an genetically inherited pathological condition where the septum between the ventricles of your heart is too thick. Additionally, the actual arrangement of the cardiomyocytes (heart muscle cells) is non-uniform and looks haphazard, so the heart does not necessarily contract efficiently anyway. In athletes, it is normal for the left ventricle to become concentrically and eccentrically hypertrophied (i.e. The walls get thicker and the chamber expands so the proportions are the same). In hypertrophic cardiomyopathy, the eccentric hypertrophy (the chamber itself getting bigger) doesn't really happen as much. Therefore you're in a situation where your heart is getting thicker and the amount of space for blood to pump through isn't getting big enough. Eventually, what kills people is that the outflow tract from the left ventricle becomes obstructed due to this thickening and you die suddenly.In normal endurance athletes, however, your heart becomes enlarged, but it does so proportionally. Therefore your heart chamber is bigger, but the walls are thicker as well to accommodate the larger volume. This is not a pathological condition nor is it risky. In fact, your heart is now healthier and stronger in every possible way!In individuals with congestive heart failure, due to excessive volume load the chamber gets bigger but the heart walls do not get thicker, so it continuously expands until it fails. In individuals with aortic stenosis or chronically high blood pressure, the heart walls get thicker but do not expand out, so the chamber space shrinks. This also happens in the hearts of weight lifters, and I explain why in another post if that interests you.
NorCalGal wrote:
...and if Lt ventricular hypertrophy (cardiomyopathy)is a normal result from being a highly trained distance runner, why is it postulated as a cause of sudden cardiac death (e.g. Micah True, Ryan Shay, etc.). How can the same condition be both normal and dangerous?
I am not a physician but have done a fair amount of reading in the literature on this particular question. Endurance athletes are at a heightened risk of left ventricular hypertrophy. Young endurance athletes die of hypertrophic cardiomyopathy at about three times the rate of similarly aged peers who are not endurance athletes. The overall rate of death from hypertrophic cardiomyopathy is still very low.
Among older endurance athletes the circumstances are somewhat different, as they are still at somewhat heightened risk of hypertrophic cardiomyopathy but the overall rate of heart risk is still dominated by coronary heart disease.
Your question about normal and dangerous relies on a poor understanding of what those terms mean. Yes, it is both normal and dangerous that endurance athletes develop hypertrophic cardiomyopathy and it kills some of them. It is the same as saying that it is normal that younger males are aggressive drivers (statistically true) and that it kills many of them (also true).
MS3 Runner, I'm interested in the continuation of your post (re: hearts of weight lifters). Is there a simple way to screen for hypertrophic cardiomyopathy? Do you have any scientific reference articles you can point me to re: "athlete's heart" ?
Mr Obvious, hypertrophic cardiomyopathy is not a condition that can be developed out of nowhere. It is something that you have a genetic predisposition towards. Specifically, autosomal dominant inheritance. A normal healthy individual who is an endurance athlete will NOT get it. It's prevalence is about 1 in every 500 people.-MS3 Runner
Mr. Obvious wrote:
I am not a physician but have done a fair amount of reading in the literature on this particular question. Endurance athletes are at a heightened risk of left ventricular hypertrophy. Young endurance athletes die of hypertrophic cardiomyopathy at about three times the rate of similarly aged peers who are not endurance athletes. The overall rate of death from hypertrophic cardiomyopathy is still very low.
Among older endurance athletes the circumstances are somewhat different, as they are still at somewhat heightened risk of hypertrophic cardiomyopathy but the overall rate of heart risk is still dominated by coronary heart disease.
Your question about normal and dangerous relies on a poor understanding of what those terms mean. Yes, it is both normal and dangerous that endurance athletes develop hypertrophic cardiomyopathy and it kills some of them. It is the same as saying that it is normal that younger males are aggressive drivers (statistically true) and that it kills many of them (also true).
p.s. I did find this but it's almost 7 years old:
Distinguishing hypertrophic cardiomyopathy from athlete’s heart: a clinical problem of increasing magnitude and significance
The simple way to screen for HoCM is to have an echocardiogram. They can directly see your interventricular septum in real time and if it's too thick then they can make the diagnosis then and there.When you actively lift weights you are increasing your peripheral vascular resistance because the muscles are squeezing the arteries and veins. The squeezing of the veins limits venous return to the heart, and the squeezing of the arteries increases the pressure that your heart has to pump against to get blood out of it. In that respect, the heart's response is not to accomadate increased flow as in endurance exercise, but to pump harder against an increased pressure. This is analogous to the individual with high blood pressure, and in both instances the heart concentrically hypertrophies (i.e. gets thicker) without a corresponding eccentric hypertrophy (i.e. gets a bigger chamber inside).Endurance athletes get to have a bigger heart (because of increased blood flow) AND a thicker heart (because of increased demand to pump), so everything is Kosher.Here is one resource on normal athletes' hearts:http://heart.bmj.com/content/89/12/1455.fullSome on hypertrophic cardiomyopathy:http://content.onlinejacc.org/cgi/content/full/36/7/2212http://content.onlinejacc.org/cgi/reprint/42/9/1687.pdfHope this helps.-MS3 RunnerBack to studying...
NorCalGal wrote:
MS3 Runner, I'm interested in the continuation of your post (re: hearts of weight lifters). Is there a simple way to screen for hypertrophic cardiomyopathy? Do you have any scientific reference articles you can point me to re: "athlete's heart" ?
MS3 Runner wrote:
Mr Obvious, hypertrophic cardiomyopathy is not a condition that can be developed out of nowhere. It is something that you have a genetic predisposition towards. Specifically, autosomal dominant inheritance. A normal healthy individual who is an endurance athlete will NOT get it. It's prevalence is about 1 in every 500 people.
-MS3 Runner
I am not disagreeing with you. As I stated I am not a doctor but I have done quite a bit of reading. I agree that there has to be a genetic inheritance involved in hypertrophic cardiomyopathy. Physiological and pathological hypertrophy can be confused. However the literature is clear that for those who are predisposed endurance training appears to induce hypertrophic cardiomyopathy. The increased rate of death in endurance athletes is well documented but still very low overall.
MS3 Runner--thanks for the article links and the information. Much appreciated.
I think my confusion has arisen over the seeming interchangeability with which the terms "enlarged heart", "cardiomyopathy", and "athlete's heart" are used in the media when reporting on stories such as Micah True and Ryan Shay's death.
Mr. Obvious, you're far too civil for this forum :). The reason that HoCM gets so much press is because it's the #1 cause of sudden cardiac death in individuals less than 30 years old. Older folks die from heart problems ALL the time (e.g. 500,000 per year), but it's especially shocking to see it in someone we perceive to be healthy.
As for the OP, yes these terms sometimes get thrown around interchangeably in the media, although they shouldn't. Glad to help.
[/quote]
I am not disagreeing with you. As I stated I am not a doctor but I have done quite a bit of reading. I agree that there has to be a genetic inheritance involved in hypertrophic cardiomyopathy. Physiological and pathological hypertrophy can be confused. However the literature is clear that for those who are predisposed endurance training appears to induce hypertrophic cardiomyopathy. The increased rate of death in endurance athletes is well documented but still very low overall.[/quote]
Yes an echo is the good standard for diagnosing HoCM, but in the real world you probably won't get an echo covered by insurance,nor will your doctor want to order one in a perfectly healthy young runner. It's not used for screening. The doctors physical exam, specifically listening to your heart, is the screening tool. Bring up your concern, they can have you do certain maneuvers like squatting, laying down, and squeezing your hands to help them hear things. At most, they may check an ecg ( your heart rhythm on a strip of paper) because it's quick and cheap. There is a lot of talk about using ecg's on every young athlete during screening physical exam. I actually just read an interesting article about it from a group of Stanford cardiologists a couple days ago. Hope this helps