Heart Conditions Don’t Just Affect Older Adults

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This article was written by Julianne Wyrick.

February is American Heart Month. Sponsored by the American Heart Association, American Heart Month is a time to battle cardiovascular disease and educate people on what they can do to live heart-healthy lives. Heart disease, including stroke, is the leading cause of death for men and women in the United States.

How much do you know about the condition of your heart? Heart health awareness typically focuses on heart disease in older adults caused by an unhealthy diet and a lack of exercise. But what if you could be at risk for cardiac arrest and sudden death even though you are young and in shape?

Image credit: Heart arrhythmia via Shutterstock

Long QT syndrome (LQTS) is one of several sudden arrhythmia death syndromes, a class of conditions affecting the heart’s rhythm. People can be born with an inherited form of the syndrome or acquire it during their life. LQTS can cause sudden, uncontrollable, dangerous heartbeats in response to exercise or stress. LQTS can arise from mutation of one of several genes, including Potassium Channel, Voltage-gated, KQT-like Subfamily, Member 1 (KCNQ1); Potassium Channel, Voltage-gated, Subfamily H, Member 2 (KCNH2); and Sodium Channel, Voltage-gated, Type V, Alpha Subunit (SCN5A).

LQTS is common; approximately one in every 2,500 people has the disorder [1]. Some people don’t discover they have LQTS until the sudden unexplained death of a family member. However, if identified, LQTS can be treated with medications, limited physical activity, or, in some cases, medical devices or surgery [2].

Dr. Brian Delisle, a faculty member of the University of Kentucky’s College of Medicine, is studying the genetic form of LQTS in order to identify new treatments. According to Delisle, there are several types of the genetic form of LQTS, each caused by a different gene mutation. One form of LQTS syndrome, LQT2 (which involves mutations of the human ether-a-go-go related gene (hERG), also known as KCNH2), is caused by a mutation in a gene that codes for potassium channels in the heart’s cells. The mutation prevents the potassium channels from being transported to their proper place at the cell’s surface. As a result, the potassium channels cannot function properly.

In a recent study published in the American Journal of Physiology Cell Physiology, researchers from Delisle’s laboratory found that a distinct cellular compartment in cardiac myocytes (heart cells) negatively regulates the production and movement of LQT2 [3]. Delisle said:

We do have a series of drugs that can correct this … in cell systems. But the problem right now is that most of the drugs that do this actually cause the acquired form of Long QT.

Delisle hopes that by better understanding the mechanism preventing the proper transport of the potassium channels to the cell’s surface, other therapeutic approaches can be identified to correct this problem.

About the author: Julianne Wyrick is a senior biochemistry major at Asbury University. A 2011 Kentucky Academy of Sciences award winner for scientific research, following graduation Julianne plans to enter a health and medical journalism graduate program.

References

1. Long QT Syndrome. Sudden Arrhythmia Death Syndrome (SADS) Foundation. Accessed 2012 Jan 28.
2. Long QT Syndrome. Mayo Clinic. Accessed 2012 Jan 28.
3. Smith et al. Trafficking-deficient hERG K? channels linked to long QT syndrome are regulated by a microtubule-dependent quality control compartment in the ER. Am J Physiol Cell Physiol. 2011 Jul;301(1):C75-85. Epub 2011 Apr 13.
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