Heart palpitations don’t usually produce dramatic visible signs on the outside of your body. What they “look like” is mostly what they feel like: a sudden awareness of your heartbeat that can range from a gentle flutter to a hard, pounding sensation in your chest, throat, or neck. In some cases, you or someone nearby might notice a visible pulse jumping at the side of the neck, or a slight rhythmic movement in the chest wall, but most palpitations are an internal experience rather than something you can see.
What Palpitations Feel Like
People describe heart palpitations in a handful of consistent ways. Your heart may feel like it’s beating too fast, pounding hard enough to notice, fluttering rapidly, flip-flopping in your chest, skipping a beat, or adding an extra beat. Some people notice the sensation only in the chest. Others feel it rise into the throat or the sides of the neck, where large blood vessels sit close to the skin’s surface.
A skipped beat is one of the most common types. What’s actually happening is a premature heartbeat, a contraction that fires slightly early. The beat itself is often too weak to feel, so what you notice is the stronger-than-normal beat that follows, plus the brief pause before it. That pause-then-thump pattern is what creates the flip-flopping or “my heart just stopped for a second” sensation.
Pounding palpitations feel different. Instead of a skip, you’re aware of each heartbeat hammering in your chest, sometimes for seconds, sometimes for minutes. This can happen during exercise, after caffeine, or during a surge of adrenaline, and it often comes with an elevated heart rate you can confirm by checking your pulse.
What You Might See From the Outside
Most palpitation episodes produce no visible signs at all. When they do, the most common is a rapid or irregular pulse visible at the neck, where the carotid artery runs just beneath the skin. If you’re thin or the episode involves a fast heart rate, you might see a fluttering movement there. Occasionally, a strong pounding heartbeat can produce a faint visible movement on the left side of the chest wall, but this is uncommon in people with a normal body build.
More noticeable are the secondary signs that sometimes accompany palpitations: flushing, sweating, or looking pale. These aren’t caused by the palpitation itself but by the adrenaline response your body mounts when it senses something unusual happening in the chest.
What Palpitations Look Like on a Heart Monitor
If you’ve ever wondered what a doctor actually sees when they catch a palpitation on a heart tracing, it depends on the type of irregular beat involved.
Premature ventricular contractions (PVCs), the most common source of skipped-beat palpitations, show up as wide, oddly shaped spikes on an EKG that appear earlier than the next normal beat should. They’re followed by a noticeable pause before the rhythm resumes. PVCs can occur in patterns: every other beat (called bigeminy), every third beat (trigeminy), or in pairs. They’re considered frequent if they show up more than 5 times per minute on an in-office EKG, or more than 10 to 30 per hour on a portable monitor worn throughout the day.
Premature atrial contractions (PACs) look different. They originate higher up in the heart’s electrical system, so the spike on the tracing is narrower and closer to the shape of a normal heartbeat. PACs are extremely common and almost always harmless.
If the palpitation involves a sustained fast rhythm, such as a run of rapid beats lasting several seconds or longer, the tracing may show supraventricular tachycardia (a fast rhythm from the upper chambers) or, less commonly, ventricular tachycardia (a fast rhythm from the lower chambers). The distinction matters to your doctor because it changes how the episode is managed.
Smartwatch and Wearable Readings
Consumer devices like the Apple Watch and Fitbit can detect some palpitations, but they work differently from a medical EKG. Most use a light-based sensor on your wrist that measures the time between pulses. Algorithms then flag irregular intervals. These devices are reasonably good at detecting sustained irregular rhythms like atrial fibrillation, but they can produce inconclusive tracings that need a clinician to interpret. A single-lead EKG from a smartwatch gives less information than the standard 12-lead version used in a clinic, so a wearable reading is a useful screening tool, not a diagnosis.
What Causes Them
Roughly a third of palpitation cases trace back to stress, anxiety, or heightened body awareness rather than a heart rhythm problem. Another 16% are caused by atrial fibrillation, about 10% by other fast-rhythm conditions, and around 6% by medications or substances like caffeine, nicotine, or stimulant drugs. Structural heart disease accounts for only about 3% of cases, and dangerous ventricular arrhythmias for about 2%.
Caffeine is a frequent suspect, though the relationship is individual. Some people can drink several cups of coffee with no effect on their heart rhythm, while others notice palpitations after a single espresso. The same goes for alcohol, dehydration, poor sleep, and hormonal shifts during menstruation, pregnancy, or menopause. Low levels of potassium or magnesium can also make the heart more electrically irritable, increasing the chance of premature beats.
How Long Episodes Typically Last
A single skipped beat or flip-flop lasts less than a second. Brief clusters of premature beats might come and go over a few seconds to a minute. Sustained episodes where the heart races at 150 beats per minute or higher can last minutes to hours, depending on the underlying rhythm. In general, palpitations that last only a few seconds and resolve on their own are far less likely to reflect a serious problem than episodes lasting minutes or longer, especially if they come with other symptoms.
Signs That Need Urgent Attention
Palpitations on their own are usually benign, but certain combinations signal something more serious. A racing heart paired with dizziness or lightheadedness warrants emergency evaluation. So does a palpitation episode accompanied by chest pain, sudden collapse, or loss of consciousness. Palpitations that start abruptly during exertion and make you feel like you might faint fall into the same category. These combinations can indicate a rhythm disturbance that affects the heart’s ability to pump blood effectively.
How Doctors Catch Them
The challenge with palpitations is that they often vanish before you reach a doctor’s office. A standard 12-lead EKG captures only about 10 seconds of heart activity, so it works well if you’re having symptoms right then but misses intermittent episodes. For palpitations that come and go, doctors use portable monitors. A Holter monitor records continuously for 24 to 48 hours. Patch monitors can extend that to one or two weeks. For very infrequent episodes, an implantable loop recorder, a tiny device placed just under the skin of the chest, can monitor for up to three years.
The principle is straightforward: the less often your symptoms occur, the longer the monitoring period needs to be to catch them. Your doctor will also typically order blood work to check thyroid function and electrolyte levels, since both can trigger or worsen palpitations.