Is this lesser-known arrhythmia making your heart race?
Since I was 13, my heart has jumped into marathon speeds with no warning while I’m doing nothing more exertive than sitting on a comfy chair watching TV. I thought everyone’s heart did this until I was diagnosed with Supraventricular tachycardia (SVT) at age 26. SVT is a rapid heartbeat that can start and stop suddenly with no warning, often for no apparent reason, and a new study estimates that 1 in 300 people in the U.S. have experienced it.
More serious irregular heartbeats such as AFib grab all the headlines but, statistically, you are more apt to need to know what to do if your heart suddenly races into SVT. Cape Cod Healthcare Cardiac Electrophysiologist Adam Mohmand-Borkowski, MD, PhD, has answers.
“SVT is seen in a wide range of ages, from young people to the very elderly. It’s related to abnormal electrical activity in the heart, starting in the upper chambers, the atria, and it can last for seconds or hours,” he said. “In addition to a rapid heart rate, other associated symptoms of supraventricular tachycardia can be light-headedness, dizziness, shortness of breath and chest pain. However, it is usually not a life-threatening condition.”
Diagnosing SVT
Diagnosing SVT involves documenting the cardiac event, which is unpredictable and can last for short periods. Dr. Mohmand-Borkowski detailed the progression of tests used to diagnose the condition:
- The first step is an electrocardiogram, an EKG, but this only records the heart’s electrical activity for a few seconds and is not portable, he explained.
- Portable Holter monitors record electrical activity continuously for a few days. Patches or electrodes are attached to your chest, and the monitoring device, which is about the size of a small cell phone, hangs from your neck in a pouch.
- If the patient has not experienced rapid heartbeat while wearing the Holter monitor, he said doctors can try a portable event monitor, which can be worn for a month or longer. Instead of recording continuously, it records when patients activate it. Nowadays, most event monitors will automatically start recording if an abnormal heart rhythm is detected.
- In rare cases, physicians can put a subcutaneous chip (implantable loop recorder) under the skin if episodes are very infrequent but associated with serious symptoms, such as syncope, and their irregular heartbeats cannot be documented otherwise.
According to Dr. Mohmand-Borkowski, wearable devices like smart watches that record patients’ heart rates can be very good initial screening tools.
“With SVT the heart rate is no longer under our brain control; the racing heartbeat starts and stops suddenly. Smart watches can tell us there is something unusual going on,” he said.
What to Do if Your Heart Races
What to do depends on the severity of your condition: the length and symptoms, according to Dr. Mohmand-Borkowski. Start with vagal maneuvers, he said. These are simple ways to try to stimulate the nervous system, which has a direct effect on the heart rate. Vagal maneuvers include certain body positions or pressing certain areas in the body, stimulating the gag reflux or bearing down as if to have a bowel movement. According to the National Institutes of Health, vagal maneuvers have a 20 to 40 percent success rate of conversion back to sinus rhythm.
“If your heart rhythm continues at a rapid pace for an extended period or if you experience any of the other symptoms, call an ambulance,” he said. EMTs are trained to deal with SVT and can be helpful in diagnosing SVT using an EKG.
According to a study published by the National Institutes of Health, SVT is common in clinical practice and a relatively common occurrence in the emergency department.
At the ER, you’ll be given an EKG, and Dr. Mohmand-Borkowski said patients can then be given medications to break the SVT rhythm and return the heartbeat to normal.
If SVT is symptomatic or occurs more frequently, doctors can prescribe calcium channel blockers or beta blockers that can be taken daily to better control the heart rhythm and prevent SVT, he said.
Additionally, heart ablation can be performed to correct the electrical circuitry problem within the heart. Dr. Mohmand-Borkowski said this procedure is usually very effective but reserved for individuals with significant symptoms or who experience recurrent SVT.
Living with SVT
If you’ve been suffering in silence or are frightened because your heart has taken you to the races once or twice, it may help to know you’re not alone. As someone whose heart has jumped into SVT dozens of times, I was the perfect candidate for surgery.
As a teenager, I said nothing because I thought it was normal to have a heart that occasionally felt as if it was going to beat out of my chest, then abruptly return to normal. I innately controlled my episodes of SVT by laying down and breathing in a way that I now understand were vagal maneuvers. That worked until the day when, at 26, the SVT refused to stop, and I asked a coworker to drive me to an emergency room. There, an EKG clearly confirmed SVT. The drug Verapamil given intravenously successfully cardioverted my SVT, and it felt great to finally feel my heart slow down gradually and begin to beat normally instead of the usual jerking stop I was used to.
After my second trip to the ER, doctors prescribed daily oral medication: first, calcium channel blockers, which caused severe side effects; then a beta blocker, which helped. Over the next six years, however, the incidence of SVT became increasingly frequent—ultimately averaging 11 trips to the ER a year. Eliminating caffeine and added sugars (goodbye chocolate!) from my diet helped. The threat of SVT kept me from eating even one M&M for 21 years.
When I was pregnant, I had to be cardioverted twice. Three years after my son was born, I knew it was time to try surgery, and the electrophysiologist was able to find an extra electrical circuit in my heart and use radiofrequency ablation to remove it. In the subsequent two decades, I’ve only jumped into SVT five times, and each time except the first, I was able to break the irregular beat in less than 10 minutes and without a trip to the ER. The first time was shortly after my heart surgery, and the cardiologist immediately re-prescribed beta blockers, which I rely on for a steady, comforting beat to this day.
Dr. Mohmand-Borkowski said that treating patients with SVT is particularly satisfying because the procedure and available treatments are highly effective and make a difference in people’s lives.
