Wide QRS Complex Tachycardia

What is Wide QRS Complex Tachycardia?

The human heart has its own electrical system which lets it beat at a specific rhythm and forms a pulse, one of the six main signs of life. The heart has a ‘pacemaker’, which sets the pace for the heartbeats. This intricate electrical system makes all the heart cells beat together. A heartbeat, or pulse, can be described as regular or irregular, fast or slow. If a person’s pulse is not within what is seen as normal, then we say they have an arrhythmia, a heartbeat disorder. Tools such as electrocardiograms (also known as EKGs or ECGs) are used to detect any irregularities in a patient’s heartbeat and pulse.

We can classify arrhythmias by the speed of the heart beats (tachycardia refers to a heart rate of over 100 beats per minute, while bradycardia means a slower heartbeat), the regularity of the heartbeats, and by the width of the QRS complex (a part of the heartbeat on the EKG).

In order to understand the condition called Wide QRS complex tachycardia (WTC), we need to explain some fundamental concepts. The QRS complex on an EKG represents a process in the heart called ventricular depolarization. To clarify, a normal heartbeat begins with an electrical signal from the sino-atrial (SA) node. This impulse then travels from the SA node to the atrioventricular (AV) node. The healthy pathway for this electrical signal goes from the AV node down to the bundle of His, Purkinje fibers and then to the ventricular myocardium causing them to contract. When changes to the heart form alternative conduction pathways, it can cause the electrical signal to go in reverse. Depending on which route the electrical signal takes, it will change how the QRS complex appears on the EKG.

A normal QRS on an EKG should be less than 0.12 seconds (120 milliseconds), therefore a wide QRS will be greater than or equal to 0.12 seconds. A Wide QRS complex tachycardia, or WCT, is a cardiac disorder that causes a heart rate of over 100 beats per minute with a wide QRS.

This article will discuss the causes of WCT, its occurrence, evaluation, management, treatment, outcomes, complications, and how to prevent it. It’s important to note that, in an emergency, when a patient’s health is unstable, the primary concern of doctors isn’t to perfectly interpret the type of WCT. Because of the numerous complications and difficult criteria to remember in an emergency, diagnosing WCT accurately and promptly remains an issue. The most essential step in such a situation is to stabilize the patient, and then diagnose the type of WCT later.

What Causes Wide QRS Complex Tachycardia?

When a patient is in a stable condition and there is enough time, understanding the cause of a fast heartbeat with wide QRS complex (a pattern shown on an electrocardiogram or heart monitor) can help doctors manage the patient’s care more effectively and greatly lower the risk of potential health issues or death. Here are some known causes of this type of fast heartbeat, which are also factors doctors consider when making a diagnosis:

“Sodium channel blockade” (this happens when the pathways that allow sodium ions to move in and out of your heart cells, which is necessary for normal heart rhythms, become blocked)
Excess levels of potassium in your blood (“Hyperkalemia”)
Abnormal levels of magnesium in your blood (“Hyper-” or “Hypo-magnesemia”)
“Supraventricular tachycardia” or SVT, a type of fast heartbeat that originates in the upper chambers of your heart, accompanied by pre-existing or a rate-related “Bundle branch block” or BBB (a blockage in one of the branches that carry electrical signals to parts of your heart)
SVT accompanied by abnormal conduction (or electricity flow) through the heart
A type of irregular heartbeat (“Atrial fibrillation” or Afib) accompanied by a rare heart disorder called “Wolff-Parkinson-White syndrome” or WPWS
“Mono-morphic ventricular tachycardia” or VT, a type of fast heartbeat that originates from the lower chambers of your heart
A life-threatening, irregular heartbeat (“Ventricular fibrillation” or VFib)
“Polymorphic VT” (a type of VT that presents with multiple different shapes of QRS complex, known as “torsades de pointes”)
“Pacemaker mediated tachycardia” or PMT, a type of fast heartbeat that may occur in people with a pacemaker

Drug overdose and toxicities (for example, from drugs such as TCAs, digitalis, cocaine, lithium, or diphenhydramine) can also cause this condition, as well as some disturbances in the EKG signals that can sometimes occur following the resuscitation of a patient.

Risk Factors and Frequency for Wide QRS Complex Tachycardia

Wide QRS complex tachycardia is a heart condition that can be caused by different factors. However, two of these causes, known as VT and VF, are responsible for most heart-related deaths in the U.S., with about 300,000 people dying from these conditions every year. Out of these two causes, VT is the most common, accounting for about 80% of all cases, especially in those with heart conditions like myocardial infarctions or coronary artery disease, where the likelihood increases to 90%. The third most likely cause is another type called SVT, although this is less common. Amongst the various types of SVT, the one most likely to cause wide QRS complex tachycardia is called conduction with aberrancy, which is responsible for approximately 21% of cases.

Signs and Symptoms of Wide QRS Complex Tachycardia

When a doctor first sees a patient with a wide complex tachycardia (WCT), they must quickly determine if the patient is stable or not. First, they’ll look at the patient’s airway, breathing, and circulation. If a patient is unstable due to WCT, they might have symptoms like confusion, low blood pressure, issues with their lungs, or other signs that their body isn’t getting enough oxygen. These can include paleness, bluish skin, and a lower body temperature.

Once a patient is considered stable, the doctor will need to quickly check their health history. This is crucial because a patient’s condition can worsen suddenly. During a WCT episode, patients often have persistent chest pain, which may be accompanied by:

Shortness of breath
Excessive sweating
Dizziness
Nausea

A patient’s medical history can provide useful information to help the doctor figure out what might be causing the WCT. For example, if a patient has a history of heart problems, like a heart attack, heart disease, or heart failure, this might make them more likely to have WCTs. The doctor will also need to know about any medication the patient is taking, especially if they are antiarrhythmic drugs, as these can also provoke arrhythmias. Additionally, if a patient has a pacemaker, it could be somehow causing the WCT.

Physical examinations can provide hints toward diagnosing VT, which can look very similar to WCT. The doctor will look for signs that the top and bottom parts of the heart are beating independently. While these signs won’t definitively confirm VT or dismiss SVT as a cause, they’re still worth checking for. Some physical techniques, known as vagal maneuvers, are also helpful in distinguishing between slow and fast heart rates.

Testing for Wide QRS Complex Tachycardia

Doctors need to closely monitor patients with wide complex tachycardia (WCT), an abnormal heart rhythm, as the patient’s condition can change suddenly, leading to serious complications like cardiovascular collapse. In this situation, an EKG, a test that measures the electrical activity of the heartbeat, is going to be a critical tool in diagnosing the exact cause of the WCT. In fact, any heartbeat irregularity that’s picked up by an EKG should be assumed to be ventricular tachycardia (VT), an alarming type of irregular heartbeat, until proven otherwise. Despite various methods and guidelines, accurate and quick diagnosis of WCT still poses a challenge as about 10% of cases remain misdiagnosed.

A technique called the Traditional Criteria was initially used to pin down the exact nature of WCTs. Later, new step-by-step processes followed that incorporated the principles of the Traditional Criteria, with the most popular one being the Brugada algorithm. Other algorithms that prove to be better than Brugada were developed but they take longer to go through, which can be a hindrance in emergency situations.

Medical associations like the American College of Cardiology (ACC), the American Heart Association (AHA), and the European Society of Cardiology (ESC) have also published a method for examining WCTs in patients stable enough to undergo such an assessment. This process involves paying close attention to elements of the patient’s medical background such as previous heart attack, history of congestive heart failure, chest pains, advanced age, structural heart disease, and certain physical symptoms.

When analyzing an EKG, certain patterns suggest VT. Some of these include, an irregular heartbeat, fusion beats and capture beats (indicating irregular rhythm), abnormal direction of the heart’s electrical activity (NW axis), and large R or Rs wave in limb lead aVR, absence of RS complexes in precordial leads (leads V1-V6).
On the other hand, supraventricular tachycardia (SVT), another type of abnormal heart rhythm, would be more likely if there is evidence of a typical bundle branch block (BBB) or fascicular block.

Another important thing to note is that if the pattern of the heartbeat during normal rhythm is similar to the pattern during an irregular heartbeat episode, this could possibly suggest either SVT or VT. The characteristics of the rhythm as well as a history of anti-arrhythmic medication use can be factors in this case. In instances where the irregular heartbeat has an uneven rhythm, there could be an underlying issue such as atrial fibrillation (AFib) with Wolff-Parkinson-White syndrome (WPWS), and incorrect management could lead to serious complications.

Physical tests like vagal maneuvers (for example, carotid sinus massage, Valsalva, coughing, etc.) that tend to reduce the heart rate can also be useful in distinguishing between SVT and VT. Tachycardia, a term for a fast heart rate, that goes away with these maneuvers is most likely due to SVT. While tachycardia caused by VT generally does not settle down with these maneuvers, VT can sometimes be stopped by them.

Treatment Options for Wide QRS Complex Tachycardia

When a patient arrives at the emergency room with a rapid heartbeat condition known as Wide Complex Tachycardia (WCT), doctors must take immediate steps to assess and stabilize the patient. They check the patient’s airway, breathing, and circulation, and also monitor the patient’s overall stability. If the patient isn’t able to maintain their airway or breathe, the doctors would insert a tube to help with breathing. If the patient’s oxygen level is low, supplemental oxygen would be provided. If the heartbeat can’t be detected, doctors would start CPR and follow advanced cardiac life support guidelines.

At this stage, they put in an intravenous line and start constant monitoring of the heart’s electrical activity and blood pressure. If the patient is found to be unstable with a rapid heartbeat condition called WCT, a procedure called cardioversion or defibrillation could be performed to get the heart back to a normal rhythm. How this is done depends on whether or not the patient has a pulse.

With a pulse, doctors would go for “synchronized cardioversion”, a method where the shock is timed according to the heart’s natural rhythm, reducing the risk of inducing a cardiac arrest. Without a pulse, it’s considered a cardiac arrest and “defibrillation” is immediately required, a process where an electric shock is given to the heart to restart its rhythm.

In patients who are stable, medication according to the latest guidance from the American Heart Association (AHA) would be given along with cardioversion. It’s extremely important for doctors to think about factors like heart attack, electrolyte imbalances, and medication side effects that could be causing the heart’s instability because some of these causes can be easily treated. When doctors are not sure of why the WCT has happened, they would manage it as if it is due to a dangerous fast heart rhythm condition involving the lower chambers of the heart called ventricular tachycardia (VT), as it’s the most common cause and has serious consequences if managed incorrectly.

In deciding which medication to use, doctors have to make an educated guess whether the WCT originates from the upper chambers (atria) or lower chambers (ventricles) of the heart. For a fast rhythm condition involving the upper chamber of the heart called supraventricular tachycardia (SVT), a drug called adenosine would be given. If it is atrial fibrillation (a fast, irregular rhythm) but with an abnormal conduction pattern, it would be treated with amiodarone, and if it’s atrial fibrillation with a normal conduction pattern, either a calcium channel blocker or a beta-blocker could be used. Conversely, for ventricular arrhythmia like VT or ventricular fibrillation, amiodarone would typically be the first choice, and lidocaine could be a second choice. However, lidocaine should never be used if the origin of WCT is not known. If the EKG shows a specific kind of abnormal heart rhythm known as Torsades de Pointes, then magnesium would be given, with an option to pace the heart at a faster rate (overdrive pacing) if Torsades de Pointes persists despite giving magnesium.

It’s crucial to accurately diagnose the cause of the patient’s WCT as the treatment may differ, for example, if a patient has a condition where the lower chambers of the heart beats fast and regularly (VT) as opposed to an upper chamber fast rhythm condition (atrial fibrillation), the treatment options would be different. Misdiagnosis could lead to serious complications. Similarly, it is crucial to correctly diagnose VT from SVT, as their treatments differ.

Another crucial aspect is to know if the patient may have an alternative conduction pathway in the heart that’s not typical. Some drugs could potentially worsen the heart rhythm, favorable to the abnormal circuit if this is the case. For patients with a known permanent pacemaker who presents with WCT, the pacemaker should be considered as a potential cause of the rapid heartbeat and would be managed differently. Here, a magnet would be placed over the pacemaker which could terminate this abnormal heart rhythm by disabling the pacemaker’s sensing of the tiny electrical signals of the top chamber of the heart (atria) and essentially make it work in an independent or asynchronous way.

When diagnosing Wide Complex Tachycardia (WCT), a type of rapid heart rhythm, doctors typically investigate various potential causes. Some of these could include:

Supraventricular tachycardia (SVT) with a pre-existing bundle branch block (BBB)
SVT with rate-related BBB
SVT with abnormal conduction
Atrial fibrillation (a heart rhythm disorder) with Wolff-Parkinson-White syndrome (a heart condition)
Ventricular tachycardia (a rapid heartbeat) and fibrillation (an irregular, rapid heart rate)
Polymorphic VT (a particular type of ventricular tachycardia)
Pacemaker-induced rapid heart rate
Drug overdose (i.e., specific medications like TCA’s, digitalis, cocaine, lithium, diphenhydramine)
Hyperkalemia (high potassium in the blood)
Either too much or too little magnesium in the body
Issues post-resuscitation
An artifact (mistake) on the EKG, a test that measures heart activity

In addition to these possibilities, certain genetic disorders that affect the heart may also be involved. These include:

Long QT syndrome and Short QT syndrome (heart rhythm conditions that can cause fast, chaotic heartbeats)
Hypertrophic cardiomyopathy (heart muscle disease)
Familial dilated cardiomyopathy (a heart condition affecting the heart muscle)
Brugada syndrome (a potentially harmful genetic condition that affects the heart’s electrical system)
Catecholaminergic polymorphic ventricular tachycardia (a condition that can cause a rapid heart rhythm in response to physical activity or emotional stress)
Arrhythmogenic right ventricular dysplasia (a heart disease that can cause irregular heartbeats)

fIt’s crucial for any healthcare professional to be thorough in their investigation to get an accurate diagnosis. They will consider all these potential causes when assessing a patient’s condition.

What to expect with Wide QRS Complex Tachycardia

While there are many reasons, or ’causes’, that might lead to a wide-complex tachycardia (WCT, a certain type of irregular heart rhythm), how well the patient will do can depend on how long the heart rhythm issue lasted, how it affected the stability of the patient’s normal bodily functions, and whether the patient experienced any complications after the event.

Patients who have normal bodily functions when they first experience WCT and have their irregular heart rhythm stopped quickly tend to recover better than those whose normal functions are affected because they are less likely to experience complications. Another important factor in recovering well is preventing the irregular heart rhythm from happening again.

Patients with a history of ventricular tachycardia (VT, an irregular heartbeat that originates in the bottom chambers of the heart) or at increased risk for it may be able to have an implantable cardioverter-defibrillator (ICD) device put in their body. This device helps regulate the heartbeat, improving both the patients’ chances of recovery and survival. Another possible treatment is catheter ablation, which can also help the patient recover properly.

Another potential issue during a WCT event is a heart attack, which can make the patient’s condition worse due to the increased risk of sudden death. The left ventricular ejection fraction (LVEF, a measure that shows how well the left side of your heart pumps with each beat) is strongly associated with how a patient might recover and can help determine those who are at risk for sudden cardiac death. Patients with an LVEF of less than 30% are considered to have an overall yearly risk of death that is close to 10%.

Possible Complications When Diagnosed with Wide QRS Complex Tachycardia

Ventricular Tachycardia, or VT, is the most common cause of Wide Complex Tachycardia (WCT). The impact of this heart condition depends on how long and how often the abnormal heart rhythm occurs, as well as any existing risk factors. It’s more common in individuals who have a history of heart conditions like artery disease or past heart attacks.

Common Problems Associated with Ventricular Tachycardia:

Frequent fainting spells and related physical injuries
Reduced blood flow due to heart’s decreased pumping ability, which can lead to heart failure

Although the history of heart disease can itself cause complications, it increases the risk for the most feared outcome of VT – sudden cardiac death. This is a sudden, unexpected death due to heart problems, often happening immediately or within an hour from the onset of symptoms. Sudden cardiac death often results from VT deteriorating into a deadly irregular heart rhythm, known as Ventricular Fibrillation, or Vfib.

In the United States, sudden cardiac death accounts for 15% of all deaths and over half of all heart-related deaths. It’s important to note that some sudden cardiac deaths are due to inherited familial disorders. Therefore, it’s crucial for people with family members who have died of sudden cardiac death at a young age to be thoroughly evaluated.

Preventing Wide QRS Complex Tachycardia

Heart disease is the biggest risk factor for Wide Complex Tachycardia (WCT), the most common type of rapid heart beat. So, to effectively fight against and prevent this condition, it’s important to cut down the risk of heart disease. You can achieve this by living a healthier lifestyle. This involves regular exercise, eating a balanced diet, losing weight, managing stress in a healthy way, quitting smoking, limiting how much alcohol you drink, and avoiding illegal drugs, such as cocaine.

For those who already have heart disease, the best way to stop this rapid heartbeat from happening is to frequently touch base with your regular doctor, take your prescribed medications correctly, keep a close eye on your blood pressure, and make sure your blood sugar and cholesterol levels are managed. Plus, don’t forget those healthy lifestyle changes. There’s a rare type of this fast heartbeat, known as idiopathic VT, that can affect people who have no history of heart disease.

Frequently asked questions

Wide QRS Complex Tachycardia (WCT) is a cardiac disorder characterized by a heart rate of over 100 beats per minute and a QRS complex on an EKG that is greater than or equal to 0.12 seconds. It occurs when there are changes to the heart's electrical conduction pathways, causing the electrical signal to go in reverse and altering how the QRS complex appears on the EKG.

Wide QRS Complex Tachycardia is responsible for approximately 21% of cases.

Signs and symptoms of Wide QRS Complex Tachycardia (WCT) can include: - Confusion - Low blood pressure - Issues with the lungs - Paleness - Bluish skin - Lower body temperature - Persistent chest pain - Shortness of breath - Excessive sweating - Dizziness - Nausea These symptoms indicate that the body is not getting enough oxygen, which can be a result of WCT. It is important for doctors to quickly determine if a patient with WCT is stable or not, as unstable patients may exhibit these symptoms and require immediate medical attention. Additionally, a patient's medical history, such as a history of heart problems or the use of certain medications, can provide useful information in diagnosing the cause of WCT. Physical examinations, including checking for signs of independent beating of the top and bottom parts of the heart and performing vagal maneuvers, can also aid in distinguishing between different types of tachycardia.

There are several known causes of Wide QRS Complex Tachycardia, including sodium channel blockade, excess levels of potassium or magnesium in the blood, supraventricular tachycardia (SVT) accompanied by bundle branch block or abnormal conduction, atrial fibrillation (Afib) accompanied by Wolff-Parkinson-White syndrome (WPWS), monomorphic ventricular tachycardia (VT), ventricular fibrillation (VFib), polymorphic VT, pacemaker mediated tachycardia (PMT), drug overdose and toxicities, and disturbances in EKG signals following resuscitation.

The doctor needs to rule out the following conditions when diagnosing Wide QRS Complex Tachycardia: 1. Supraventricular tachycardia (SVT) with a pre-existing bundle branch block (BBB) 2. SVT with rate-related BBB 3. SVT with abnormal conduction 4. Atrial fibrillation (a heart rhythm disorder) with Wolff-Parkinson-White syndrome (a heart condition) 5. Ventricular tachycardia (a rapid heartbeat) and fibrillation (an irregular, rapid heart rate) 6. Polymorphic VT (a particular type of ventricular tachycardia) 7. Pacemaker-induced rapid heart rate 8. Drug overdose (i.e., specific medications like TCA’s, digitalis, cocaine, lithium, diphenhydramine) 9. Hyperkalemia (high potassium in the blood) 10. Either too much or too little magnesium in the body 11. Issues post-resuscitation 12. An artifact (mistake) on the EKG, a test that measures heart activity 13. Long QT syndrome and Short QT syndrome (heart rhythm conditions that can cause fast, chaotic heartbeats) 14. Hypertrophic cardiomyopathy (heart muscle disease) 15. Familial dilated cardiomyopathy (a heart condition affecting the heart muscle) 16. Brugada syndrome (a potentially harmful genetic condition that affects the heart's electrical system) 17. Catecholaminergic polymorphic ventricular tachycardia (a condition that can cause a rapid heart rhythm in response to physical activity or emotional stress) 18. Arrhythmogenic right ventricular dysplasia (a heart disease that can cause irregular heartbeats)

The types of tests that are needed for Wide QRS Complex Tachycardia include: 1. EKG (Electrocardiogram): This test measures the electrical activity of the heartbeat and is critical in diagnosing the exact cause of the tachycardia. Abnormalities in the EKG can suggest ventricular tachycardia (VT) or supraventricular tachycardia (SVT). 2. Medical history assessment: This involves examining the patient's medical background, including previous heart attack, history of congestive heart failure, chest pains, advanced age, structural heart disease, and certain physical symptoms. 3. Physical tests: Vagal maneuvers, such as carotid sinus massage, Valsalva maneuver, and coughing, can be useful in distinguishing between SVT and VT. Tachycardia that goes away with these maneuvers is likely due to SVT, while tachycardia caused by VT generally does not settle down with these maneuvers. 4. Additional tests: Depending on the specific case, additional tests such as blood tests, echocardiogram, stress test, or cardiac catheterization may be ordered to further evaluate the condition and determine the appropriate treatment.

Wide QRS Complex Tachycardia (WCT) can be treated in several ways depending on the patient's stability and the presence or absence of a pulse. If the patient is stable, medication according to the latest guidance from the American Heart Association (AHA) would be given along with cardioversion. The choice of medication depends on whether the WCT originates from the upper chambers (atria) or lower chambers (ventricles) of the heart. For a fast rhythm condition involving the upper chamber of the heart called supraventricular tachycardia (SVT), a drug called adenosine would be given. If it is atrial fibrillation with an abnormal conduction pattern, it would be treated with amiodarone, and if it's atrial fibrillation with a normal conduction pattern, either a calcium channel blocker or a beta-blocker could be used. Conversely, for ventricular arrhythmia like ventricular tachycardia (VT) or ventricular fibrillation, amiodarone would typically be the first choice, and lidocaine could be a second choice. However, lidocaine should never be used if the origin of WCT is not known.

When treating Wide QRS Complex Tachycardia (WCT), there can be potential side effects associated with the medications used. The specific side effects may vary depending on the medication being administered. Some possible side effects include: - Adenosine: flushing, shortness of breath, chest discomfort, dizziness, headache - Amiodarone: nausea, vomiting, dizziness, fatigue, liver toxicity, lung toxicity - Calcium channel blockers: low blood pressure, dizziness, constipation, headache - Beta-blockers: low blood pressure, fatigue, dizziness, bronchospasm (in patients with asthma or chronic obstructive pulmonary disease) - Lidocaine: dizziness, confusion, numbness or tingling, seizures (in high doses) - Magnesium: flushing, warmth, low blood pressure, drowsiness, muscle weakness It's important to note that these are potential side effects and not everyone will experience them. The benefits of the medication should be weighed against the potential risks and side effects. Additionally, individual patient factors and medical history should be taken into consideration when determining the appropriate treatment and potential side effects.

The prognosis for Wide QRS Complex Tachycardia (WCT) depends on several factors, including the duration of the irregular heart rhythm, the impact on the patient's normal bodily functions, and the occurrence of complications. Patients who have normal bodily functions when they first experience WCT and have their irregular heart rhythm stopped quickly tend to recover better than those whose normal functions are affected. Preventing the irregular heart rhythm from happening again is also important for a good prognosis.

You should see a cardiologist for Wide QRS Complex Tachycardia.