What is Pulseless Ventricular Tachycardia?
Pulseless ventricular tachycardia is a severe heart condition where the regular contractions of the heart are replaced by fast but ineffective ones. This condition can reduce the flow of blood to the organs and can lead to heart failure. It is considered a medical emergency.
When the heart contracts quickly, the ability of the heart chambers to be filled with blood decreases, leading to a drop in blood flow from the heart. This is why a pulse may not be felt. Certain observations in heart’s electrical activity can help identify pulseless ventricular tachycardia: a heart rate exceeding 100 beats per minute, wide and abnormal heartbeats, disconnection between the upper and lower chambers of the heart, the occurrence of unusual heartbeats and certain electrical orientation in heart’s functioning. There are ways to distinguish this condition from other heart rhythm abnormalities with similar wide and abnormal heartbeats, but 90% of time, these symptoms point towards ventricular tachycardia.
Pulseless ventricular tachycardia can either have consistent (“monomorphic”) or changing (“polymorphic”) heartbeat patters. The main reason for this condition is a lack of sufficient blood supply to the heart.
What Causes Pulseless Ventricular Tachycardia?
Pulseless ventricular tachycardia (VT) is a condition where the heart beats at an unusually rapid pace, but no pulse is felt. This can be due to several reasons and conditions. These include diseases affecting the structure and function of the heart, abnormalities in blood mineral levels, specific drugs or medications, and inherited conditions causing problems with heart’s electrical activity.
The most common cause for fast heartbeats, including pulseless VT, is when a person has a disease affecting the structure of the heart. Here are some examples in each category:
Diseases working on heart structure:
* Coronary artery disease (narrowing or blockage of the heart’s blood vessels)
* Aortic stenosis (a narrowing of the heart’s main gateway)
* Cardiomyopathy (diseases of the heart muscle)
* Congestive heart failure (a chronic condition where the heart does not pump blood efficiently)
* Hypertrophic obstructive cardiomyopathy (abnormal growth in a part of the heart muscle that can obstruct blood flow)
* Myocardial infarction (heart attack)
Abnormal mineral levels in blood:
* Low potassium (hypokalemia)
* High potassium (hyperkalemia)
* Low magnesium (hypomagnesemia)
* Low calcium (hypocalcemia)
Inherited conditions affecting how the heart’s electrical system work:
* Lange-Nielsen Syndrome (an inherited disorder characterized by deafness and long QT interval, an abnormality of the heart’s electrical activity)
* Romano-Ward Syndrome (another type of long QT syndrome, but without deafness)
* Brugada Syndrome (a disorder characterized by abnormal electrocardiogram findings and an increased risk of sudden cardiac death)
Abnormal heart rhythms:
* Wolf-Parkinson-White Syndrome (an extra electrical pathway in the heart)
* Catecholamine Sensitive Polymorphic Ventricular Tachycardia (a condition where excitement or exercise triggers fast heartbeats)
Certain drugs or medications that can prolong the time taken for heartbeats:
* Antibiotics like Clarithromycin, Erythromycin, and Fluoroquinolone varieties, such as ciprofloxacin
* Metoclopramide, a medication used to treat stomach issues
* Certain psychiatric medications like Haloperidol
* Methadone, a medication used for pain relief or to help with withdrawal from opioids
* Droperidol, a medication mainly used against nausea
* Anti-vomiting medication (ondansetron)
* Medications used to correct heart rhythm
There’re other causes can also lead to pulseless VT:
* Low blood volume (hypovolemia)
* Low oxygen (hypoxia)
* Acidosis (high acid levels in body fluids)
* Low body temperature (hypothermia)
* Tension pneumothorax (a severe condition where air accumulates in a space around the lungs)
* Cardiac tamponade (fluid build-up in a layer of the heart, obstructing its action)
* Pulmonary embolism (a blockage in a blood vessel in the lung).
Risk Factors and Frequency for Pulseless Ventricular Tachycardia
Ventricular tachycardia, or VT, is a leading cause of sudden heart-related deaths in the United States, contributing to around 300,000 deaths every year. This condition tends to affect adults over 35 and is responsible for at least half of the deaths linked to irregular heart rhythms. It has been suggested that VT accounts for between 30% and 75% of cases where heart failure occurs outside of the hospital, even though we’ve seen more instances of electrical activity in the heart without a pulse recently. There isn’t a concrete incidence rate for VT because if it happens without witnesses, it quickly degenerates into a state of no heartbeat. While the death rate from heart artery disease is decreasing and lifesaving services are advancing, survival rates for VT incidents, especially those occurring outside hospital settings, remain low, with less than 10% of patients surviving.
polymorphic nature of the tachycardia, the long QT interval and the initiation
of the tachycardia with a late coupled P.V.C.
Signs and Symptoms of Pulseless Ventricular Tachycardia
Pulseless ventricular tachycardia is a serious heart condition. Prior to experiencing an attack, patients often suffer from chest pain, palpitations, shortness of breath, feeling faint, and fainting. During a physical exam, doctors might note poor blood circulation, low blood pressure, rapid breathing, a swelled neck vein, and an abnormal S1 heart sound. If not treated promptly, this can lead to a sudden collapse because of weak heart contractions and low blood flow.
During an attack, patients become unconscious and unresponsive, and no pulse can be felt. It’s of utmost importance to start defibrillation, a treatment to restore the heart’s normal rhythm, as soon as possible. Any delay can significantly decrease chances of survival, and the patient may die within minutes.
- Chest pain
- Palpitations
- Shortness of breath
- Feeling faint
- Fainting
- Poor blood circulation
- Low blood pressure
- Rapid breathing
- Swelled neck vein
- Abnormal S1 heart sound
- Sudden collapse due to weak heart contractions and low blood flow
- Unconscious and unresponsive state with no palpable pulse during an attack
- Urgent need for defibrillation to restore the heart’s rhythm
Testing for Pulseless Ventricular Tachycardia
Diagnosing pulseless VT, a type of irregular heart rhythm, depends on a physical exam and an electrocardiogram (ECG), which is a test that checks the electrical activity of your heart. Once this issue is confirmed, immediate life-saving steps, governed by the Advanced Cardiac Life Support guidelines, should be taken.
The ECG will typically reveal the following signs: consistent gaps between heartbeats (R-R intervals), a fast ventricular rate with an unclear atrial rate (meaning your lower heart chambers are beating quickly and it’s tough to see how fast the upper chambers are beating), AV dissociation (meaning your upper and lower heart chambers are not working together), and a wide QRS complex (referring to a specific pattern seen on the ECG when the lower heart chambers are activated).
There are specific ECG criteria designed to help diagnose VT. These include:
– Classical Criteria that look for signs like AV dissociation, abnormal heart beats (capture or fusion beats), negative or positive concordance, and certain changes in the QRS pattern.
– Brugada Criteria, which looks for the absence of certain ECG patterns, the length of certain intervals on the ECG, AV dissociation, and also assesses for the classical criteria above in specific ECG leads.
– Vereckei Criteria, which also observes for AV dissociation, and focuses heavily on the lead aVR (a specific viewpoint of the heart on ECG).
At the core, the American Heart Association suggests that the diagnosis of VT should consider the following signs: AV dissociation, a QRS complex longer than 0.14 seconds, a monophasic R wave in aVR, certain QRS morphologies, the absence of an RS complex in all precordial leads, and an RS interval longer than 100 ms in at least one precordial lead.
Treatment Options for Pulseless Ventricular Tachycardia
Pulseless ventricular tachycardia is a critical health emergency where proper medical treatment must follow specific protocols. In plain language, it’s a severe heart condition where the heart beats very fast, but in an irregular way, that it can’t pump blood effectively. It’s vital to treat this condition promptly, as delays could lower survival rates.
Immediate treatment often involves high-energy shocks delivered from a defibrillator, a machine that helps to restore the heart’s normal rhythm. After this treatment, it is crucial to perform cardiopulmonary resuscitation (CPR), a lifesaving procedure involving chest compressions and breaths, until the defibrillator is ready for use again. Providing oxygen and using certain medications are also part of the treatment.
Once the heartbeat returns to a normal rhythm, it’s essential to keep a close eye on the patient. If the heart’s irregular rhythm was corrected quickly within about a minute, the body doesn’t usually suffer from significant disorders caused by high acidity levels in the blood, a condition known as metabolic acidosis. However, if the patient remains unresponsive, a procedure known as therapeutic hypothermia might be initiated. This involves lowering the body’s temperature to aid in recovering neurological function if the event occurred outside the hospital.
In all cases of pulseless ventricular tachycardia, it’s common to consider a heart attack (or acute myocardial infarction) as a possible cause. In some feasible cases, a procedure known as coronary angiography and percutaneous coronary intervention (PCI), which helps open up blocked coronary arteries, might also be considered.
Alongside defibrillation, medical treatment usually involves the use of certain medications injected into a vein. These include medications that increase blood pressure (vasopressors) and those that help regulate the heart’s rhythm (antiarrhythmic drugs). One common drug in this situation is amiodarone, known for preventing sudden cardiac death. Sotalol, an alternative, may slightly decrease the efficacy of defibrillation. Still, people using beta-blocker medications generally have lower death rates.
For patients at a high risk of having their heart go into an irregular rhythm again, or those who have had this happen before, a device called an implantable cardiac defibrillator (ICD) might be recommended. ICD is an electronic device inserted into the chest that can help regulate fatal heart rhythm disorders, enhancing survival rates compared to just medication treatment.
What else can Pulseless Ventricular Tachycardia be?
Several signs can suggest that a person is experiencing ventricular tachycardia, which is a type of fast heart rate. These signs include:
- A QRS complex (a reading from an electrocardiogram, or EKG) that is greater than 0.14 seconds with right bundle branch morphology or greater than 0.16 seconds with left bundle branch morphology
- An RS interval (another EKG measurement) that is longer than 100 ms in a precordial lead
- AV dissociation (when your heart’s upper and lower chambers don’t work together as they should)
- Negative QRS concordance in the precordial leads (a specific pattern on an EKG)
- Ventricular fusion beats (where two different signals arrive at the ventricle, or lower chamber of the heart, at the same time)
However, if the patient’s condition allows, doctors may want to consider other potential causes of a fast heartbeat. This condition, known as wide-complex tachycardia, can sometimes be due to other issues like supraventricular tachycardia (SVT) with aberrant conduction, or SVT with pre-excitation and antidromic atrioventricular reentrant tachycardia (AVRT). That said, the majority of cases are due to ventricular tachycardia. As a rule, every wide complex tachycardia should initially be treated as ventricular tachycardia until proven otherwise.
What to expect with Pulseless Ventricular Tachycardia
The chances of recovery from pulseless ventricular tachycardia, a type of serious heart rhythm problem, greatly depend on how quickly the heart rhythm is restored to normal using a procedure called defibrillation. Survival rates increase if the defibrillation is done quickly, with as much as 50% of patients surviving if treated promptly. However, any delay in treatment can significantly lower the survival rate – waiting up to 15 minutes could drop survival to just 5%.
The patient’s outcome is not just about the speed of treatment; it’s also tied to their overall heart health and any other medical conditions they may have. This includes whether they have heart disease that’s causing a lack of blood flow to the heart (ischemic heart disease) or any physical changes or damage to the heart’s structure (structural heart disease).
Possible Complications When Diagnosed with Pulseless Ventricular Tachycardia
When ventricular tachycardia (a fast heart rate that begins in the ventricles) occurs without a pulse, it can lead to a heart attack and inadequate blood flow to organs, causing most complications. If the fast heart rate lasts longer than 3 minutes, it can lead to a lack of oxygen to the brain (anoxic brain injury), causing life-long neurological problems. Anoxic brain injury is one of the issues that can happen after a heart attack.
Other problems that can happen after a heart attack include heart dysfunction and a response of the body to a lack of blood flow and its restoration (systemic ischemia/reperfusion response). Heart dysfunction, caused by lack of blood supply, can lead to a temporary malfunction of the heart. This is a common cause of death soon after a heart attack. The restoration of blood supply after a period of lack of supply can lead to the activation of immune and blood clotting pathways, causing a risk of multiple organ failure and infections. This also reduces blood volume, impairs regulation of blood vessels, and disrupts oxygen delivery to organ tissues. The treatment for these conditions after a heart attack includes monitoring blood pressure, managing airways, and checking the brain function.
Common Problems After a Heart Attack:
- Fast heart rate that begins in the ventricles (ventricular tachycardia)
- Heart attack
- Inadequate blood flow to organs
- Anoxic brain injury
- Life-long brain damage
- Heart dysfunction
- Response to a lack of blood flow and its restoration
- Temporary heart malfunction (myocardial dysfunction)
- Multiple organ failure
- Infections due to immune activation
Treatments Include:
- Hemodynamic monitoring
- Airway management
- Brain function assessments
Preventing Pulseless Ventricular Tachycardia
Pulseless ventricular tachycardia, a potentially life-threatening heart condition, is most often caused by a lack of blood supply to the heart, also known as cardiac ischemia. If you have ischemic heart disease, it’s important to make lifestyle changes such as eating a low cholesterol and low salt diet and exercising regularly. If you smoke, it’s strongly recommended that you quit. It’s very important to see a heart specialist, called a cardiologist, regularly. This will ensure that the root cause of your heart condition is being properly treated and to prevent the condition from happening again. If your heart rhythm problem was caused by a side effect of a medication, it’s vital to understand properly how to use the medication. This will help you avoid this condition in the future.
