What is Sinus Tachycardia?
Sinus tachycardia is a condition where your heart beats faster than usual, which results in your heart pumping more blood than normal. It’s normal to experience sinus tachycardia when exercising or feeling stressed, but it can be a sign of concern if it happens while you’re at rest. For adults, a normal resting heart rate varies but typically falls between 60 and 100 beats per minute. Factors such as physical fitness level and other existing health conditions can influence this rate. For children, the normal resting heart rate depends on their age but is usually higher than adults. In infants, it normally starts between 100 and 150 beats per minute and gradually slows down over the next six years.
If your heart rate is consistently high while at rest, it may be an early warning sign of a serious health problem. Therefore, it’s crucial for doctors to quickly figure out what’s causing the high heart rate and decide whether immediate medical attention or treatment is needed. This article aims to discuss the possible causes of a high heart rate and how doctors approach patients who have this condition.
What Causes Sinus Tachycardia?
Tachycardia, or a fast heart rate, can be caused by a variety of things. Normally, exercise, stress, pain, and anxiety can speed up your heartbeat. But sometimes, it’s a sign of a health problem related to your heart or another part of your body.
Heart-related causes of tachycardia include:
* Rapid heart rhythms that start in the upper chambers of the heart. This can show up on a heart rhythm test as a narrow peak. If the rhythm is steady, it might suggest conditions like an extra signal in the heart or diseased heart tissue. If the rhythm is irregular, it could suggest conditions like a quivering heart muscle, a rapidly beating section of the heart, a block in the electrical signals of the heart, and more.
* Rapid heart rhythms that start in the lower chambers of the heart. This can show up on the heart rhythm test as a wide peak. They can be brief or long-lasting. If the peak shape is constant, it’s classified as having one shape. If the peak shape changes, it’s classified as having multiple shapes.
* A form of rapid heart rhythm with many shapes that is caused by either a long peak-to-peak time on the heart rhythm test, resulting from birth defects or certain conditions. Certain factors can increase your risk for this rhythm, including medications that lengthen the time between heartbeats, being female, low potassium, low calcium, low magnesium, blocked arteries, and heart disease.
* Inflammation of the heart muscle, often due to a virus. Other causes of inflammation include infections like bacteria, medications, poison, reactions to medications or insect venom, autoimmune diseases, low body temperature, blocked arteries, radiation, and rejection of a heart transplant item.
* A build-up of fluid around the heart that increases pressure in the space around the heart. This can lead to symptoms like low blood pressure, swollen veins in your neck, dull heart sounds, changes in blood pressure during breathing, and a change in the shape of the wall that divides the chambers of your heart.
* Blocked blood flow to the heart. This can show up as chest pain, non-ST elevation myocardial infarction (NSTEMI), and ST-segment myocardial infarction (STEMI). You’re at a higher risk if you’re overweight, have high cholesterol, high blood pressure, diabetes, are older than 50, male, smoke tobacco, or have a family history of heart disease.
Other causes of tachycardia include:
Respiratory:
* Blockages in the lung blood vessels. These can be sudden, ongoing, or both. The most common event is when a clot breaks off from the deep veins and enters the lungs. But fat from an orthopedic injury, fluid from pregnancy, and air from putting a tube in a vein can also cause these blockages.
* Lack of oxygen in various body tissues. This can happen if your body can’t take in oxygen, carry the oxygen, or exchange gases properly.
Gastrointestinal/Renal/Electrolyte:
* Low glucose in the blood. This often comes as a side effect of medication. Other causes include serious illnesses, drinking alcohol, endocrine disorders, weight loss surgery, metabolic disorders, certain types of adrenal gland tumors.
* Body fluid imbalances. If your body doesn’t take in enough fluids or loses too many fluids, your heart rate can increase.
* High potassium in the blood. Most of the time, this is due to labs making mistakes like a blood sample breaking down. It can also happen if your kidneys aren’t working properly, if you’re breaking down muscle tissue, if you’re exercising too much, have metabolic acidosis (too much acid in the body), lack of insulin, cancer breaking down rapidly, medication-induced, and high potassium intake.
* Low magnesium in the blood. This can happen if you take in or absorb too little magnesium, and your kidneys filter out or excrete too much magnesium. This can be due to birth defects or conditions you get later in life. Conditions that can affect your magnesium level include prolonged suctioning through a nose tube, malabsorption, acute inflammation of the pancreas, refeeding syndrome, late pregnancy, breastfeeding, uncontrolled diabetes with sugar in the urine or kidney complications of diabetes, increased urine after a kidney injury, injury to the part of the kidney that first filters the blood, or medications that act on the kidney.
* Low calcium in the blood. This can happen if you don’t get enough sunlight, have a poor diet, malabsorption, surgery to prevent obesity, end-stage liver disease, chronic kidney disease, a form of rickets that depends on vitamin D, low magnesium, high phosphorus, certain medications, transferring a lot of blood with a substance that prevents clotting, serious illness, spread of cancer to the bone, inflammation of the pancreas, breakdown of muscle tissue, and unique mitochondrial gene defects (cells’ energy producers).
Infectious Disease:
* A body-wide inflammation due to an infection that causes organ damage. This is a common cause of death in the United States. This can be mild or severe. Early on in this condition, the inflammation will lower the resistance of your blood vessels. To make up for this, your body will speed up your heart rate. This is especially true in pediatric patients who might have blood pressures from normal to high during this period.
Vascular:
* An acute condition where not enough blood gets to your tissues leading to a lack of oxygen. There are four kinds of shock- distributive, hypovolemic, cardiogenic, and obstructive. Distributive shock is caused by low resistance in your body’s blood vessels secondary to sepsis, system-wide inflammation, severe allergic reactions, neurologic injuries, or endocrine disorders. Hypovolemic shock results from low blood volume and can be due to bleeding or dehydration. Cardiogenic shock is due to low output from the heart. This can be caused by heart attacks that cause significant dead heart tissue or rupture the heart muscle or valves, inflammation of the heart muscle, fluid around the heart, tearing of the main artery, acute heart rhythms, and medications harmful to the heart, especially in an overdose. Obstructive shock is caused by inappropriate heart output in the setting of normal blood volume and heart function. Common causes include collapsed lungs, fluid around the heart, rigid or crescent-shaped heart muscle, significantly blocked lung clots, a narrow aorta, or another heart blockage.
Hematologic (blood-related):
* Loss of a significant amount of blood due to an injury. There are four levels of bleeding. The highest level, Class IV, is more than 40% blood loss with significant tachycardia (an increase in pulse of 40%), low blood pressure, rapid breathing, no urine production, and lethargy (lack of energy).
* A condition where the body does not have the appropriate amount of oxygen-carrying protein or red blood cells. This can be sudden or long-term and can be microcytic, normocytic, and macrocytic. Microcytic anemia can be due to a lack of iron, lead exposure, or an inherited blood disease. Normocytic anemia can be due to cancers, bleeding, rupture of red blood cells, chronic diseases, aplastic anemia, bone marrow failure, and other syndromes. Macrocytic anemia can be from lack of vitamin B12 or folate, underactive thyroid, medications, alcoholism, liver disease, or a blood disorder where the bone marrow does not make enough healthy blood cells.
Toxicology:
* Ingesting certain substances can cause tachycardia, including: albuterol, amphetamines, medications that block certain signals in the body, antihistamines, atropine, caffeine, carbon monoxide, substances that deprive cells of oxygen, sedatives, antipsychotic medication, cocaine, medications that increase the force of muscle contractions, medications that cause blood vessels to dilate, drugs that increase heart rate, chemicals that are harmful when swallowed, medications for an overactive thyroid, medications for attention deficit hyperactivity disorder (ADHD), certain antipsychotic medications, potassium, decongestant drugs, medications for motion sickness, medications for asthma, certain antidepressant drugs.
* Withdrawal from certain substances or medications can also cause tachycardia, including: alcohol, benzodiazepines, beta-blockers, medications that act like the calcium channel blockers, epilepsy medications, a type of blood pressure medication, medications from a certain plant used to treat heart conditions, opioids, insecticides, a decongestant drug, certain rat poisons, sedative-hypnotics (class of drugs that includes sleeping pills and tranquilizers).
Endocrinologic (hormone-related):
* Pregnancy results in many changes to the body, including increased heart rate, cardiac output, and blood volume.
* Hyperthyroidism, or an overactive thyroid, often presents with a fast heartbeat, an involuntary shaking of your body, excessive sweating, swelling, overactive reflexes, weight loss, and changes to the skin and nails. It can also cause heart rhythm problems such as a quivering heart muscle.
* Tumors of the adrenal gland and extra-adrenal autonomic tissue produce chemicals that can cause tachycardia, excessive sweating, diarrhea, high blood pressure, weight loss, and worry.
Risk Factors and Frequency for Sinus Tachycardia
Sinus tachycardia is a condition where the heart rhythm is usually fast, irregular, and doesn’t last for a long time. There is a form of it called ‘inappropriate sinus tachycardia’ that doctors diagnose when they can’t find an underlying cause for the fast heart rate. It’s not a common condition and is often seen in young women and healthcare professionals. Another condition related to a fast heart rate is ‘Postural orthostatic tachycardia syndrome’. It is also commonly seen in young women and often occurs after stressful situations like infections, pregnancy, surgery, or physical injuries.
Signs and Symptoms of Sinus Tachycardia
Sinus tachycardia is a condition where the heart beats faster than normal but still maintains a regular rhythm. People with sinus tachycardia might not experience any symptoms. However, they might also feel their heart beating faster than usual, which is known as palpitations. There can be other symptoms too, depending on what’s causing the fast heartbeat. These could include shortness of breath (dyspnea), chest pain, feeling lightheaded or dizzy, fainting (syncope), and near fainting (presyncope).
A detailed medical history is essential in deciding how to manage sinus tachycardia. Key considerations would be potential triggers such as fever or exercise, recent medications, exposure to toxins, use of drugs or caffeine, previous illnesses, history of heart disease or recent heart surgery, and family history.
During a physical exam, it’s vital to assess the patient’s circulation (hemodynamic status). This helps to stabilize the patient and makes sure they’re not about to collapse due to a sudden drop in blood pressure (shock). The doctor will also listen to the heart for signs of tachycardia and check for distant heart sounds, which could indicate fluid buildup around the heart (pericardial effusion with tamponade), a larger amount of blood than usual leaving the heart during each heartbeat (pulsus paradoxus), third or fourth heart sounds or a double beat (gallop rhythm) indicating heart muscle dysfunction, and heart murmurs that could indicate structural heart disease.
Testing for Sinus Tachycardia
The process of assessing constant, high heart rate when at rest, known as sinus tachycardia, requires careful research. The first step for your doctor will be to check if a high heart rate is a normal reaction in the particular circumstance. Then, the focus shifts to finding the root cause of this condition.
Multiple tests can be done for this investigation. These include an electrocardiogram (a test that measures the electrical activity of the heartbeat), a 24-hour Holter recording (a continuous tape recording of a patient’s EKG for 24 hours), pulse oximetry (a test used to measure the oxygen level of the blood), an echocardiogram (an ultrasound of the heart), arterial blood gas (measures the levels of oxygen and carbon dioxide in the blood), lactic acid level, a chest x-ray, D-dimer (a small protein fragment present in the blood after a blood clot is degraded), a chest computed tomography with angiography (a type of imaging test), a ventilation-perfusion scan (a type of lung imaging test), cardiac enzymes levels, glucose level, electrolytes, complete blood count (a blood test used to evaluate your overall health), and/or a toxicology screen (a test that is used to check for drugs).
The electrocardiogram is often the first test done to confirm the presence of sinus tachycardia and to rule out other types of rapid heart rhythms. A 24-hour Holter recording is useful to confirm the ongoing presence of sinus tachycardia. Pulse oximetry is a quick way to find out if there is low oxygen in your blood. An echocardiogram can be used to see if heart failure could be the cause. Arterial blood gases are performed to determine the presence of acidity and if it is related to the level of carbon dioxide or a metabolic problem. Lactic acid levels can show if there is not enough oxygen reaching the tissues in the body.
A chest X-ray is useful to find a potential source of an infection, heart failure, or a collapsed lung. The D-dimer test, chest computed tomography scan, and ventilation-perfusion scans are used to look for the presence of a lung clot. The glucose and electrolyte levels tests are used to identify possible metabolic problems. A complete blood count can help identify the presence of anemia and infection. A toxicology test can detect the presence of legal, illegal, and harmful substances that could cause a high heart rate, including substances like cocaine or caffeine.
Treatment Options for Sinus Tachycardia
The key to managing a fast heart rate (known as sinus tachycardia) is to identify and address its root cause. It’s important to note that not all cases of sinus tachycardia are a cause for concern. For example, a fast heartbeat brought on by physical activity or stress often does not need specific heart treatments.
However, if a person’s sinus tachycardia is due to a serious medical condition that could potentially get worse (such as sepsis, shock, low oxygen levels, metabolic acidosis or a recent heart attack), it is crucial to admit the patient for an immediate check-up. In these cases, treatment should be centered around tackling the underlying issue causing the fast heartbeat.
What else can Sinus Tachycardia be?
If your heart beats super fast, or ‘tachycardia’, your healthcare provider will need to distinguish it from a normal heartbeat pattern or other fast heartbeat disorders. Here’s a look at how different conditions appear on an electrocardiogram (a test that measures your heart’s electrical activity):
- Normal sinus rhythm: Regular heartbeat pattern with a rate of 60 to 100 beats per minute.
- Sinus tachycardia: Same pattern as a normal heartbeat, but the rate is over 100 beats per minute.
- Supraventricular tachycardias: The heartbeat rate is over 100 beats per minute, and the electrical signal travelling through the heart (QRS) is quick, under 120 milliseconds.
- Atrioventricular nodal reentrant tachycardia: This type of fast heartbeat comes on and off suddenly. It has a rate of 120 to 220 beats per minute, and the EKG might show irregular P waves, ST depression, and T wave inversions.
- Atrial fibrillation: Your heart rhythm is irregularly irregular, meaning it’s unpredictable and chaotic. The EKG will not show clear P waves, and the rate at which the lower chambers of the heart beat can exceed 100 beats per minute.
- Atrial flutter: This condition is known for its “sawtooth” pattern on an EKG but doesn’t have visible P waves.
- Ventricular tachycardias: The heartbeats are fast (over 100 beats per minute) and the QRS complex is noticeably wide (over 120 milliseconds). This can appear in two forms: polymorphic (changing) or monomorphic (unchanging).
Then, there’s also ‘inappropriate sinus tachycardia’, where your heart beats over 100 times per minute even when you’re resting. This is not due to any physical, medical, or drug causes.
You might also have Postural Orthostatic Tachycardia Syndrome. It’s a condition where your heart rate increases by 30 beats or more per minute, or over 40 beats in 12 to 19-year olds, when you move from lying down to standing up. This usually happens in young women with no heart defects, and without any significant changes to your blood pressure or pulse rate.
Once the doctor spots that you have sinus tachycardia, they’ll work to find the root cause. This will involve ruling out serious cardiac and non-cardiac causes that may need urgent evaluation and treatment.
What to expect with Sinus Tachycardia
Constant rapid heart rate when at rest, known as persistent sinus tachycardia, should be assessed by a doctor. Detecting and addressing this condition early on may lead to positive results for the patient, although this largely depends on the root cause.
If the rapid heart rate is proven to be transient, meaning it only lasts for a short period due to a typical bodily response to stress or anxiety, it often gets better on its own.
Possible Complications When Diagnosed with Sinus Tachycardia
When continuous rapid heart rate due to a disease goes unnoticed, this can result in a decrease in blood flow to the heart, less time for the heart chamber to fill with blood, a drop in blood pump around the body and it can eventually lead to failure of various body systems. In more serious situations, it can cause heart muscle disease, heart failure, and even death.
Common Effects:
- Decrease in blood flow to the heart
- Shorter time for the heart’s chambers to fill with blood
- Drop in blood flow around the body
- Failure of various body systems
- Heart muscle disease
- Heart failure
- Potential death
Preventing Sinus Tachycardia
It’s important for patients to understand that while a fast heartbeat, or tachycardia, can sometimes be a normal body response, it can also be one of the first indications of a serious medical condition. Explaining to patients the root cause of tachycardia, especially the symptoms that come with it, is crucial for proper care and future check-ups.
If a patient experiences tachycardia along with additional symptoms such as chest pain or shortness of breath (known as dyspnea), they should be told to get medical help right away.
