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Thursday, April 23, 2015

Do we neeed to worry about the right ventricle in endurance exercise?

Is the right ventricle the Achilles heel of endurance exercise? I wrote briefly about this subject in 2007 .

In that regard there is more data now about which to fret.  A 2011 article by researchers in Australia and Belgium  gives reason to believe that endurance exercise affects the left and right ventricles differently and possibly  not in a good way .Could endurance exercise induce chronic changes in the structure of the right ventricle such that it is vulnerable to ventricular arrhythmias, similar to those related to an inherited cardiomyopathy (arrhythmogenic right ventricular cardiomyopathy).  See here. ARVC is very uncommon in the US but more commonly seen in Europe particularly in Italy where it is said to be the most common cause of sudden cardiac death in young athletes.

 The authors studied 40 well trained endurance athletes before an event , immediately afterwards and 6-11 days later.Echocardiograms were done at all three times and cardiac MRs were done at baseline. 

 Immediately post race, right ventricular ejection fraction was reduced  and RV volume was increased while comparable   changes were not present in the left ventricle. RV function did recover by one week except for an echo derived index  called "global strain".(In echo lingo strain means deformation which can be determined by tissue Doppler techniques)

Five of the 39 athletes demonstrated delayed gadolinium enhancement (DGE) in the ventricular septum. These changes believed to represent fibrosis were more common in the athletes who had  been competitive endurance athletes longer  and the authors suggested that the areas of  fibrosis noted on the gadolinium scan were in the area of the septum which bulges into the left ventricle as a result of the tissue deformation noted  in the right ventricle.

As the authors stated, the long-term clinical significance warrants further study.Will there be re-modelling of the RV in such a way as to predispose to ventricular arrhythmias?

Another publication by some of the same authors  had previously examined the prevalence of gene mutations in athletes with complex ventricular arrhythmias. Specifically they looked for desmosomal gene mutations of the type typical of ARVC ( Arrhythmogenic  Right Ventricular Cardiomyopathy). Desmosomes are complexes of protein that function to facilitate cell to cell adhesion. In 20 of the 47 cases no desmosome gene mutations was identified.A suggestion was made that prolonged endurance exercise could bring about remodeling of the right ventricle which would predispose to ventricular arrhythmias  even in some athletes who do not have the recognized desmosomal gene mutation..I wrote in more detail about this study here.

The right ventricular issue may well be worth worrying a bit about but the small but consistently  increased incidence of atrial fibrillation in long term exercisers has a more robust data base in its support


Michel Accad said...

Glad to find some helpful reviews on this topic here! Another disturbing study is the 2009 MRI findings in 102 marathon runners. http://www.ncbi.nlm.nih.gov/pubmed/19332846

Thank you!

james gaulte said...

Michel,Thanks for the reference.I thought I had blogged about that article but just realized I had left that commentary in a draft form for which which I am now hitting the publish button.Yeah, those area of presumed fibrosis bother me too.


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