Pulseless ventricular tachycardia is when the heart beats too fast, so the ventricles cannot fill with enough blood. It is a life-threatening condition that requires immediate medical treatment.

The heart has four sections called chambers. There are two upper chambers called the atria and two lower chambers called the ventricles. When the heart contracts, the ventricles pump blood to the lungs and the rest of the body. When the ventricles beat too fast, they cannot fill with blood, affecting the cardiac output, which is the amount of blood pumped out by the heart each minute. If the ventricles do not fill with blood, the cardiac output is reduced, which means the heart is pumping out less blood. 

In pulseless ventricular tachycardia, the amount of blood pumped out by the heart decreases dramatically, which results in the absence of a pulse. This means that blood and oxygen cannot reach the rest of the body, which can lead to organ failure and sudden cardiac arrest. This is when the heart stops pumping unexpectedly. 

Ventricular tachycardia

In pulseless ventricular tachycardia, a pulse cannot be felt; however, ventricular tachycardia is not always pulseless. Ventricular tachycardia is a rapid heartbeat that starts in the lower chambers of the heart. It is defined as 3 or more consecutive heartbeats at a rate of, or over, 100 beats per minute. Symptoms of ventricular tachycardia may include chest pain, a fast heart rate, shortness of breath, and dizziness. People with pre-existing heart issues such as coronary artery disease or heart failure are at a greater risk of ventricular tachycardia.¹ 

Pulseless ventricular tachycardia is a specific type of ventricular tachycardia in which the heartbeat is rapid, but a pulse cannot be felt. Pulseless ventricular tachycardia can often lead to cardiac arrest, which is when the heart stops pumping suddenly, depriving the brain and vital organs of blood and oxygen. Without rapid treatment, this can cause severe brain damage or death.

How common is ventricular tachycardia?

Ventricular tachycardia is the cause of most sudden cardiac deaths in the United States. The number of cardiac deaths is approximately 300,000 deaths per year, with at least half of these being linked to ventricular arrhythmias (abnormal heart rhythms in the ventricles).^2,3 

Causes 

Pulseless ventricular tachycardia can be linked to many causes, including structural heart diseases, diseases affecting ion channels and certain medications.⁴ The most common cause is structural heart disease. These include:

• Coronary heart disease - coronary arteries supply the heart with blood. When these arteries are narrowed because of a build-up of fatty material, the heart’s blood supply is interrupted, affecting how much oxygen reaches the heart. 
• Heart attack (myocardial infarction) - this is when the heart’s blood supply is blocked, usually due to a blood clot.
• Congestive heart failure - this is when the heart cannot pump blood as effectively as it should. 

Diseases that cause defects in ion channels can also increase the risk of pulseless ventricular tachycardia. Ion channels are proteins that help the movement of ions into and out of our cells. Diseases affecting this movement include:

• Lange-Nielsen Syndrome 
• Romano-Ward Syndrome 
• Brugada Syndrome 

Electrolytes such as potassium, sodium and calcium affect the body’s water balance, muscle function and nervous system function. Conditions that disturb the normal electrolyte balance can result in pulseless ventricular tachycardia. These include: ⁴

• Hypocalcaemia (calcium deficiency)
• Hypokalaemia (potassium deficiency)
• Hypomagnesaemia (magnesium deficiency)

Some medications that affect the heart’s electrical activity can also cause pulseless ventricular tachycardia. These include:

• Haloperidol 
• Methadone 
• Erythromycin 
• Droperidol 

Symptoms 

Patients with pulseless ventricular tachycardia are present in an unconscious and unresponsive state and lack a pulse. Before the event, they may complain of:

• Chest pain (angina)
• Heart palpitations 
• Shortness of breath
• Light-headedness 
• Fainting  

Treatment 

Treatment of pulseless ventricular tachycardia may include:

• Defibrillation - use of an electric shock to help restore the heart to a normal rhythm 
• CPR (cardiopulmonary resuscitation)
• Oxygen delivery 
• Medications to correct an irregular heartbeat, usually administered through the veins (intravenously)

Complications 

Patients will be monitored closely after the event to look out for complications such as heart failure, organ failure or metabolic acidosis, which is a build-up of acid in the body, usually as a result of kidney failure. Doctors may also cool the body once a normal heart rhythm has been reached in case of potential neurological recovery.⁴ After a case of pulseless ventricular tachycardia, doctors may also monitor patients for signs of an acute heart attack. 

Patients might also be given certain medications like amiodarone or sotalol, which are used in the prevention of sudden cardiac death. For patients with a history of ventricular tachycardia, doctors might recommend the implantation of implantable cardiac defibrillators (ICDs).¹ This device detects irregular heartbeats (arrhythmias) that may be life-threatening and then delivers an electric shock to the heart to restore a regular heart rhythm. 

Outlook

The prognosis for pulseless ventricular tachycardia depends on how long it takes to restore a normal heart rhythm and blood flow to the organs. The sooner the heart is defibrillated, the better the chances of survival, with shorter delays in defibrillation associated with up to a 50% increase in survival rates.⁴ Delays in treatment can reduce the chances of survival to as low as 5%. The outlook is also dependent on the patient’s history and whether they have any underlying heart conditions. In some cases, patients can make a full recovery, but others may have long-term neurological and cardiac consequences. 

Prevention 

Pulseless ventricular tachycardia is a serious condition with a high mortality rate. In some cases, it cannot be prevented, but in others, the risk can be mitigated by adopting a healthy lifestyle or through optimisation and management of any underlying heart conditions. Lifestyle changes like quitting smoking, a low cholesterol and low salt diet, and regular exercise can all reduce the chances of developing a heart condition. 

Smoking  

The chemicals in tobacco can cause heart disease and cancer. Cigarette smoke reduces the oxygen levels in the blood, which can raise blood pressure and heart rate because the heart has to work harder to provide enough blood and oxygen to the rest of the body. The risk of developing heart disease or other conditions is reduced after quitting smoking. 

Diet 

Eating a nutritious diet is key in preventing and managing cardiovascular disease. The consumption of a wide variety of fruits and vegetables in your diet is good for your health. Consuming whole grains, nuts, fish and poultry and reducing the dietary intake of red meat, refined carbohydrates, added sugars, and salt is beneficial. Examples of whole grains include oats, brown rice and whole-grain bread or pasta. People with a diet similar to this pattern had a 31% reduced risk of heart disease, a 33% lower risk of diabetes, and a 20% lower risk of stroke.⁵ 

Exercise 

Regular exercise can improve cardiovascular health.⁶  Long-term studies have shown that increased physical activity is associated with a decline in the risk of developing cardiovascular and respiratory diseases.⁷ Exercise does this by lowering the heart rate and strengthening the heart muscle, making it more effective at pumping blood. It can also help to lower blood pressure, which is a risk factor for heart disease.

Stress

Chronic stress can contribute to heart disease. When stressed, the body releases the hormone adrenaline, which makes the heart beat faster and increases the blood pressure. Chronic stress increases inflammation within the body, and in the long term, inflammation can lower high-density lipoprotein (HDL) cholesterol, which is sometimes called ‘good’ cholesterol. HDL cholesterol takes the cholesterol through the blood and carries it back to the liver, which flushes it out of the body. High levels of HDL cholesterol can reduce the risk of heart disease. Finding ways to cope, such as through regular exercise, can help reduce stress levels. 

Sleep

Sleeping too little or too much has been associated with heart disease and can also impact weight, blood pressure and inflammation. When we sleep, our blood pressure goes down. Having problems with sleep means your blood pressure stays higher for a longer period, which is an important factor in contributing to the development of heart disease and stroke. Inadequate sleep, which may be the result of poor sleep hygiene, sleep disorders or shift work, can also lead to higher stress levels, unhealthy food habits and less energy for physical activity. Sticking to a regular sleep schedule, sunlight exposure in the mornings and avoiding artificial light and caffeine a few hours before going to bed are all habits that can improve your sleep hygiene. 

Summary 

Pulseless ventricular tachycardia is a life-threatening condition that requires immediate intervention. Timely treatment is essential in improving survival rates and reducing long-term outcomes and complications. It can be caused by structural heart diseases, such as coronary artery disease, or by electrolyte imbalances, or certain medications. People with pulseless ventricular tachycardia lack a pulse and are unconscious. Before this, they may complain of light-headedness, chest pain and shortness of breath. Treating underlying heart conditions and maintaining a healthy lifestyle can help prevent the condition.