A heart that suddenly starts racing can be frightening, especially when it happens mid-workout or during an otherwise normal day. Many people dismiss these episodes as anxiety, dehydration, or overexertion, but doctors say there can be a clear medical explanation behind such sudden spikes in heart rate.
Maryland-based physician Dr Kunal Sood, who specialises in Anesthesiology and Interventional Pain Medicine, recently explained this phenomenon in an Instagram post. According to him, these sudden episodes are often due to supraventricular tachycardia (SVT). As he described it, “If you’ve ever felt your heart suddenly take off mid-workout, this is likely what’s happening. What you’re seeing here is an episode of supraventricular tachycardia or SVT.”
Dr Sood elaborated on how SVT differs from a normal increase in heart rate, saying, “It’s the rhythm where the heart suddenly starts beating very fast, often 170 beats per minute or higher, without gradually speeding up.”
He explained the underlying mechanism as well: “SVT happens because of an electrical short circuit in the upper chambers of the heart. Instead of signals flowing normally, they loop rapidly, forcing the heart to beat much faster than it should.”
He also pointed out common triggers, noting, “Episodes can be triggered by things like exercise, stress, dehydration, lack of sleep, or stimulants such as caffeine. That’s why it can show up unexpectedly during a run or a workout.”
Importantly, Dr Sood also outlined immediate steps that may help when such an episode strikes. “When it happens, the best first step is to stop, rest, and stay calm,” he said. He added that certain techniques may help reset the heart rhythm: “Sometimes vagal manoeuvres like bearing down as if having a bowel movement, slow deep breathing, or gently splashing cold water on your face can help reset the rhythm.”
So, how can a person tell the difference between SVT and a normal fast heart rate?
Dr CM Nagesh, honorary secretary of the Indian College of Cardiology and Founder of Cardea Super Speciality Hospital, tells indianexpress.com, “A normal fast heart rate usually builds up gradually and settles down once the trigger, such as exercise, stress, or excitement, passes. In contrast, SVT often starts and stops suddenly, without warning. People describe it as a switch being flipped, where the heart suddenly races very fast, often above 150 beats per minute, even while resting.”
He adds that SVT may also be accompanied by “symptoms such as dizziness, chest discomfort, shortness of breath, or a feeling of fluttering in the chest,” which are less familiar with a normal physiological increase in heart rate.
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Lifestyle factors that increase the risk of SVT episodes in otherwise healthy adults
Dr Nagesh informs, “Excessive caffeine intake from coffee, energy drinks, or pre-workout supplements is a common trigger, as it can overstimulate the heart’s electrical system. Poor sleep or chronic sleep deprivation increases stress hormones, making abnormal rhythms more likely. Dehydration and electrolyte imbalance, especially low potassium or magnesium, can also provoke SVT episodes. In some individuals, alcohol intake, smoking, and high emotional stress further increase susceptibility, even in the absence of underlying heart disease.”
Tests or evaluations recommended to understand the underlying cause
The first step is a detailed clinical history and physical examination, Dr Nagesh states, followed by an ECG to capture the heart’s rhythm. If episodes are intermittent, doctors may recommend a Holter monitor or event recorder to track the heart over several days or weeks.
“Blood tests are often done to check thyroid function and electrolyte levels. In selected cases, an echocardiogram is advised to assess heart structure. If episodes are frequent or severe, an electrophysiology study may be considered to identify the source of the abnormal rhythm precisely,” concludes Dr Nagesh.
DISCLAIMER: This article is based on information from the public domain and/or the experts we spoke to. Always consult your health practitioner before starting any routine.
