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What is Narrow Complex Tachycardia?

Narrow Complex Tachycardia

Author:- Mr. Ritesh Sharma

Narrow Complex Tachycardia much like its name is a complex type of tachycardia. Just like other types of tachycardias, it is also characterized by rapid heart rate causing symptoms like heart palpitations. The arrhythmia is titled so because of its presentation of abnormal ECG on being tested. The heart abnormalities illustrated in this tachycardia showcase a narrow QRS complex. 

This narrow QRS complex arises due to the conduction of the heart’s upper chambers (atria) to the heart’s lower chambers (ventricles) through the normal electrical pathways. The study of narrow complex tachycardia is deeply intricate and rooted in the complexities of the cardiovascular system. There are several types of NCTs varying in symptoms, causes, and treatment methods.

Let’s decipher all the complexities of the narrow complex tachycardia through the topics covered in a detailed and comprehensive manner below.

Understanding Narrow Complex Tachycardia

The deep understanding of narrow complex tachycardia is rooted in the realm of the electrocardiogram. It is a medical term referring to rapid heartbeats originating from the heart’s upper chambers, i.e. atria. These heartbeats conduct normally through the specialized electrical pathways to the heart’s lower chambers, i.e. ventricles. Due to this, a narrow QRS shows up in the electrocardiogram test. 

The narrow QRS complex in the ECG/ EKG indicates that the electrical impulse is traveling through the normal conduction system of the heart. The different types of NCTs differ in their effects on cardiovascular health. Moreover, this cardiac arrhythmia has multiple causes, symptoms, and underlying risk factors. We will discuss all these characteristics of narrow complex tachycardia throughout this blog. 

Types of Narrow Complex Tachycardia

There are several types of narrow complex tachycardia depending on the origin and effect on the heart. Let’s discuss these different types of arrhythmias below:-

  1. Atrial Fibrillation (Afib):-
    In this condition of tachycardia, the atria quiver instead of contracting effectively. This leads to heart palpitations due to rapid heartbeats and the QRS complex shows up narrow in the ECG test. 
  2. Atrial Flutter:-
    Atrial Flutter is also characterized by a rapid contraction of atria. However, unlike Afib, the contractions are in a more organized and regular pattern. 
  3. Supraventricular Tachycardia:-
    In this type of narrow complex tachycardia, the rapid heart rhythms start above the ventricles. SVT is further classified into various other conditions of tachycardia. These tachycardias are- AV nodal reentrant tachycardia (AVNRT), atrial tachycardia, and atrioventricular reciprocating tachycardia (AVRT). 
  4. Atrioventricular nodal reentrant tachycardia (AVNRT):-
    This is a common type of narrow complex tachycardia in the category of SVT in which the rapid heartbeats are due to an abnormal circuit in the atrioventricular node (the pathway between the sinoatrial node and the bundle of HIS and Purkinje fibers in the heart’s conduction system). 
  5. Atrioventricular Reciprocating Tachycardia (AVRT):-
    This is another form of SVT characterized by rapid heartbeats. The cause of an elevated heart rate in this tachycardia is an extra electrical pathway between the atria and the ventricles. 

Narrow Complex Tachycardia causes

Narrow complex tachycardia can be caused by various factors. The most common factors out of these are underlying heart conditions, abnormalities in the heart’s electrical conduction system, and external factors. The following are the elaborated details on all of the causes of NCT:-

  • Various Arrhythmias:-
    Various arrhythmias like atrial fibrillation, atrial flutter, and supraventricular tachycardia can trigger narrow complex tachycardia through their presence in the cardiovascular system. 
  • Structural Heart Diseases:-
    Conditions such as hypertrophic cardiomyopathy, congenital heart defects, and valvular heart diseases can cause the situation of chaos in cardiac function and ultimately lead to narrow complex tachycardia. 
  • Thyroid Disorders:-
    Hyperthyroidism which occurs due to an overactive thyroid gland can lead to situations that cause NCT. 
  • Electrolyte Imbalances:-
    Heart abnormalities caused by abnormal levels of electrolytes such as sodium, potassium, and calcium in the blood can trigger narrow complex tachycardia. 
  • Stress and Anxiety:-
    Emotional stress and anxiety stimulate the sympathetic nervous system. Due to this, the heart rate abnormally elevates and in some cases, NCT develops. 
  • Medications and Stimulants:-
    Some medications contain caffeine, nicotine, and other stimulants that exacerbate other arrhythmias and lead to the development of narrow complex tachycardia. 
  • Alcohol and Substance Abuse:-
    Excessive intake of alcohol and other addictive substances can disrupt the conduction system of the heart and result in NCT. 
  • Idiopathic Causes:-
    Sometimes, NCT occurs without any identifiable cause. In this case, the healthcare professionals conclude that the medical condition is due to an idiopathic cause and refer to it as idiopathic narrow complex tachycardia.

Narrow Complex Tachycardia Symptoms

The symptoms of narrow complex tachycardia can vary from individual to individual depending on the underlying cause of an elevated heart rate. However, the following are some common symptoms associated with the arrhythmia:-

  • Palpitations:-
    In this tachycardia, the patients tend to feel a sensation of rapid, pounding, or fluttering heartbeat. Apart from this, the patients also find their heart racing or skipping a beat if they are affected by NCT. 
  • Shortness of Breath:-
    With rapid heartbeats, the body’s demand for oxygen also increases due to which, the condition of shortness of breath arises especially when performing a physical activity. 
  • Lightheadedness or Dizziness:-
    Due to rapid heartbeats, the blood flow to the brain significantly decreases. This situation leads to lightheadedness or dizziness in patients of NCT. 
  • Chest Pain or Discomfort:-
    Some patients experience symptoms mirroring angina or a heart attack, i.e. chest pain or discomfort if they are affected by NCT. 
  • Fatigue:-
    Unexplained fatigue is another common symptom of NCT. 
  • Reduced Exercise Tolerance:-
    Palpitations and shortness of breath cause reduced exercise tolerance in patients of NCT. 
  • Nausea or Vomiting:-
    The episodes of NCT can cause gastrointestinal symptoms such as nausea or vomiting. 
  • Neck Pulsations:-
    A visible pulsation in the neck is another prominent symptom of narrow complex tachycardia. 
  • Sweating:-
    Sweating occurring in the absence of physical exertion can also indicate NCT.

Narrow complex tachycardia risk factor

There are many underlying risk factors of narrow complex tachycardia that may further exacerbate it:-

  • Age:-
    People older in age tend to be affected by heart problems more. 
  • Heart Disease:-
    People who have heart conditions like coronary artery disease, hypertension (high blood pressure), valvular heart disease, myocardial infarction (heart attack), or cardiomyopathy are likely to be affected by NCT. 
  • Family History:-
    Individuals with a family history of heart abnormalities can develop narrow complex tachycardia. 
  • Smoking and Alcohol Consumption:-
    Smoking and alcohol consumption have an adverse effect on the heart and blood vessels, so people who engage in these bad habits in excess are prone to narrow complex tachycardia. 
  • Obesity:-
    Obesity is linked to diseases such as hypertension, diabetes, and dyslipidemia, so obese people are likely to develop narrow complex tachycardia. 
  • Sleep Apnea:-
    Obstructive sleep apnea can cause NCT in individuals due to its effect on cardiovascular health. 

Narrow Complex Tachycardia treatment

The treatment for narrow complex tachycardia highly depends on the underlying causes of the arrhythmia. However, there are some common treatment approaches used by healthcare professionals in this arrhythmia:-

  • Vagal Maneuvers:-
    Some physical maneuvers, such as the Valsalva maneuver (bearing down as if having a bowel movement), carotid sinus massage, or diving reflex (immersing the face in cold water) can help in mitigating the risks of narrow complex tachycardia. 
  • Medications:-
    In the case of NCT, healthcare professionals prescribe antiarrhythmic drugs and rate control agents to patients of NCT to reduce the episodes of arrhythmia. 
  • Cardioversion:-
    If the medicines fail to cure the patients, cardioversion is used by healthcare professionals to restore the normal heart rhythm. In this, the patients are given controlled electric shocks to rest the rhythm of the heart.
  • Catheter Ablation:-
    In this process, radiofrequency energy or cryotherapy is used to destroy the causes of NCT, i.e. electrical pathways or tissues. 
  • Implantable Devices:-
    In severe cases of NCT, implantable devices like a pacemaker and an Implantable Cardioverter-Defibrillator (ICD) are used. 
  • Treatment of Underlying Conditions:-
    If the narrow complex tachycardia is due to some underlying heart conditions then they must be treated first. 

Prevention Strategies for Narrow Complex Tachycardia

While mitigating narrow complex tachycardia showing abnormal ECG might not be entirely possible with mere strategies, by incorporating them into your lifestyle you can reduce the risk of arrhythmia. 

  • Take a Highly Nutritious Diet:-
    Take a diet high in nutrition to reduce the risk of NCT and maintenance of ideal heart health. 
  • Exercise Regularly:-
    Regular exercise helps maintain a good blood flow and reduces the chance of any arrhythmia affecting you. 
  • Take alcohol and caffeine in Moderation:-
    Caffeine and alcohol can potentially trigger narrow complex tachycardia, so limit their intake. 
  • Manage Stress:-
    With exercises like yoga, deep breathing, and yoga, you must manage stress. 
  • Stay Hydrated:-
    Drink a good amount of water daily to enhance the blood flow and reduce the chances of an elevated heart rate. 
  • Go for Regular Medical Check-ups:-
    You must visit healthcare professionals for regular medical check-ups to ensure the ideal state of your heart health. 

Narrow Complex Tachycardia can be a potentially dangerous arrhythmia with its effects on heart health. It is important to identify its prominent symptoms and promptly act to mitigate this arrhythmia. Apart from this, you must adopt a healthy lifestyle to steer clear of any symptoms of underlying risk factors of this tachycardia. Promote awareness about this heart problem and prevent others from being affected by it. Stay safe and heart healthy!


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