What Is Tachycardia? (podcast)

Heart rhythm disorders, including tachycardias, mean that the heart is going faster than 100 beats per minute.

When we say top or supraventricular tachycardias, we refer to heart rhythm disorders that originate in the top two chambers.

Ventricular tachycardias can also arise from the bottom chambers. Patients can develop pretty dramatic symptoms from both disorders.

Symptoms may include lightheadedness, palpitations, feeling dizzy, almost passing out or actually passing out. The bottom chamber ventricular tachycardias can be more dangerous and have been associated with sudden cardiac death.

There’s a wide variety of different supraventricular tachycardias or tachycardias that originate in the top chamber. There are a couple of supraventricular tachycardias that can be more dangerous because they’re inherently associated with the higher risk of stroke. Those rhythm disorders are atrial fibrillation and atrial flutter.

There are other tachycardias originating from the top chamber including atrial tachycardia and others that are problematic from a symptomatic perspective, but are a little bit less dangerous to the patient.

The sinus node is the node that is the primary pacemaker cell of the heart. When we say sinus tachycardia, that means we’re having a normal heart rate, a normal physiologic response to the body’s demands. The heart rate is going fast because it’s answering the metabolic demands of the body, which could be exercise. We also see it in conditions of anemia, thyroid disorders, pulmonary embolism or a clot in the lung. We see it in various entities so we need to be careful with the clinical context.

There is also a rare entity called inappropriate sinus tachycardia where someone’s heart rate is just running too fast inappropriately. This is a more rare phenomenon, but we do come across it clinically.

There are a number of risk factors for tachycardia including lifestyle choices, such as excessive alcohol, excessive caffeine, tobacco use.

There are many other electrical reasons why we see it. There are reasons of electrical aberrations including electrolyte disorders that may make the heart more irritable and more susceptible to having an arrhythmia.

There are also states that the body can be under, including emotional or physical stress, anemia, problems with the pulmonary system.

There is a wide variety of entities that can drive these heart rhythm abnormalities and require a comprehensive evaluation to look for an underlying cause.

Ventricular tachycardia patients are typically patients who have a cardiomyopathy or abnormal heart structurally. They might have a dilated heart. They may have coronary artery disease. We see these rhythm disorders, ventricular tachycardia, when someone has a scar on the heart. These are things we want to rule out when someone has this type of abnormality identified.

There also are lifestyle reasons why someone can present with either heart rhythm disorder or either tachycardia, and that would include tobacco use, excessive alcohol use and excessive exercise, dehydration, electrolyte derangement. Those are reasons that we would look for. We also evaluate for any endocrine problem, including thyroid disorders.

Any new unexplained symptom that develops, you should see your primary care physician about. They’ll be able to take an adequate history from you and they may choose to perform what’s called a 12-lead electrocardiogram, which is a way to assess heart rhythm and it gives us a lot of information that way.

Certainly we would have a low threshold to want to see you more urgently if symptoms arise very suddenly or you’re having new dramatic symptoms of a wide variety, if you pass out, or have new, unexplained palpitations or chest pain.

There's a wide variety of symptoms that can arise from different tachycardias specifically. Often they present as palpitations, heart pulsation in the neck, nausea, shortness of the breath, exerting yourself.

When it comes to top chamber or supraventricular tachycardias, we like to address any lifestyle issues that may be contributing.

Once those issues are adequately addressed, we want to make sure we know what rhythm disorder we’re treating and if there are identifiable symptoms associated with a certain supraventricular tachycardia. Then, we would consider institution of medical therapy, medicines that would slow down conduction through the electrical fibers.

In case medical therapy fails to relieve symptoms or the rhythm disorder is persistent or patients cannot tolerate medications, we would consider a referral to one of our heart rhythm experts.

These experts perform what’s called an electrophysiology study, where they put catheters inside the heart. They put little electrodes inside the different chambers to find where exactly the heart rhythm is originating from and where they can apply what’s called radiofrequency ablation or perform a little procedure to terminate the heart rhythm disorder.

Patients tend to develop fairly dramatic symptoms if there is a recurrent or persistent heart rhythm abnormality.

If your heart rate is going very fast, in excess of 150 beats per minute for hours or days, you’ll ultimately end up with swelling and shortness of breath. You’ll end up with excessive fatigue. You just won’t feel well. Fluid can back up into the lungs in that scenario.

In case of bottom chamber arrhythmia or ventricular tachycardia, where the heart rhythm abnormalities are initiating in the right or left ventricle, these can be more dangerous. We need to be very careful when we perform a comprehensive evaluation for patients. We need to make sure they’re closely monitored. Sometimes there are even device therapies that can terminate those heart rhythm abnormalities.

There are devices called implantable defibrillators that are implanted under the skin and monitor the heart rhythm at all times.

Should someone have a dangerous heart rhythm, the devices can shock the heart out of the heart rhythm back to a normal rhythm. It can be a life-saving technology.