MB is a 39 year old male, who works full time and cycles competitively in his spare time. Like many of us, MB began riding a bike at roughly the age of 5; and rode mountain bikes throughout his youth. He slowly increased the volume and intensity of his training over a period of time. MB first tried road cycling in 2008, and began racing at the age of 31, in 2009.
During a typical week of training and racing, MB rides anywhere between 300 and 400km, over a period of 10 to 14 hours. This training includes a combination of low intensity and high intensity efforts; as well as shorter criterium races of about 1 hour, and longer road races taking approximately 2.5 hours.
While teaching RPM classes in 2008, MB noticed an occasional cardiac arrhythmia. At random times, MB’s heart rate would rapidly increase to over 220 beats per minute for a short period of time, during which he would experience a “pounding pulse and heartbeat”. The arrhythmia would last for a short period, and usually cease after MB reduced the intensity of his effort on the bike. This arrhythmia continued to appear during periods of training and racing. MB self diagnosed the condition as supra-ventricular tachycardia.
WHAT IS SUPRA-VENTRICULAR TACHYCARDIA?
Normally, the heart beats at a fairly steady rate, dependent on the needs of the body. Your heart beat is controlled by regular, mild electrical impulses, which stimulate the tissue of the heart to contract. Supra-ventricular tachycardia (SVT) is where the electrical impulses, or the atrial tissue in the heart, produce an irregular, rapid heart beat.
Around 2 out of 1000 people have SVTs, which presents as reoccurring, unexplained periods of a very rapid heartbeat. SVTs often result in a pounding feeling in the head and neck; while some less common symptoms include chest pain, uncomfortable breathing, anxiety, lightheadedness and very rarely, a loss of consciousness. The severity of these symptoms varies depending on the intensity and length of the SVT, as well as individual patient health and perceptions.
SVTs appear very rapidly, and usually stop after a short period of time. Triggers can include caffeine and alcohol intake, bending over, sudden movements, stress, physical exertion and fatigue. Diagnosis of an SVT can be determined by patient history alone; although a proper examination and ECG are a good idea, to ensure no other heart problems are present. There are a few different types of SVTs, which all have a slightly different mechanism of action.
HOW ARE SVTs MANAGED?
When SVTs appear, the immediate goal is to try and stop the heart from beating rapidly. Applying a cold pack to the face, or trying to exhale against a closed airway (the Valsalva Manoeuvre), can help with this. In some cases, medications can be used to stop an SVT and get your heart rate back to normal.
For those who experience SVTs on a regular basis, treatment is available to try and prevent their appearance. Once the exact part of the heart responsible for an SVT is determined, this very small amount of tissue can be destroyed. This type of surgery usually cures SVTs in around 95% of cases. This type of surgery is not suitable for everybody though; so medications are available to prevent the appearance of SVTs.
More detailed information on SVTs can be found in this review from the Medical Journal of Australia.
ATHLETES WITH SVT
Many professional athletes have managed to compete at the highest level of their sport with SVTs.
Nathan Eagleton, a former Australian Rules Footballer, once collapsed on the field during a game. He was diagnosed and treated with Wolf Parkinson White Syndrome…a form of SVT.
Bobby Julich, a former cyclist, was diagnosed and treated….he went on to place third in the 1998 Tour De France, and won a bronze medal in the 2004 Summer Olympic games.
Two months before competing in the 2008 Summer Olympics, volleyball player Tayyiba Haneef-Park had surgery to treat an SVT.
Rebecca Soni and Dana Vollmer, both Olympic gold medallist swimmers, have been treated for SVT surgically.
Nathan Cohen, a two time world champion rower, was diagnosed with SVT in 2013, at the age of 27.
Quite simply, suffering from an SVT will not stop your from enjoying physical activity. The condition can usually be managed and treated successfully, without limiting your sporting endeavours.
WHAT ABOUT MB???
Due to another health issue, MB spent an extended period of time off the bike completely. During this extended period of rest, he did not experience any SVTs….the problem seemed to resolve itself! This may have been because MB was able to gain adequate rest, allowing his body to treat the condition on its own. MB has begun to ride his bike and train again, with no signs or symptoms of his SVT reappearing.
Ideally, MB should have sought advice from a cardiologist; in order to obtain a definitive diagnosis and consider different treatment options. Fortunately, it seems that all MB required to treat his condition was an extended period of rest. However, I have advised MB to keep a very close watch out for further symptoms; and if any appear, to head to a heart specialist as soon as possible.