Background

The heart possesses an intricate electrical system that enables it to contract and circulate blood throughout the body in a synchronized rhythm. Normal heartbeats are orchestrated by specialized cells in the right atrium, known as the sinoatrial node. These cells transmit an electrical signal to another group of specialized cells called the atrioventricular node.

This electrical impulse then traverses through the bundle of His and Purkinje fibers to stimulate the ventricles, resulting in their contraction and the ejection of blood from the heart into the body’s arteries. A premature ventricular contraction disrupts this regular pattern by causing the heartbeat to originate from the Purkinje fibers instead of the SA node.

Because PVCs occur prior to a normal heartbeat, there is a brief pause before the next regular heartbeat. PVCs can manifest in isolated instances or as repeated patterns. When two consecutive PVCs occur, they are referred to as doublets, while three consecutive PVCs are known as triplets.

It is crucial to understand that when three or more consecutive PVCs happen, it is categorized as ventricular tachycardia. If PVCs intermittently alternate with regular sinus beats, the condition is termed bigeminy. Similarly, if every third heartbeat is a PVC, it is designated as trigeminy. In most patients, PVCs present as palpitations of the heart. Fortunately, they are typically harmless and do not necessitate any specific treatment.

Epidemiology

Premature ventricular contraction is relatively common, and they can occur in both healthy individuals and those with underlying heart conditions. The prevalence of PVCs in the general population varies, but they are often detected in individuals undergoing cardiac monitoring.

PVCs can affect individuals of all ages, but they tend to become more common with advancing age. They are often seen in older adults. There is no strong gender predilection, as both men and women can experience PVCs.

Anatomy

Pathophysiology

One key mechanism involves ectopic pacemaker cells that possess a subthreshold potential for firing. When the heart’s electrical activity reaches the threshold required for these cells to initiate a beat, an ectopic beat occurs. Another pathophysiologic rationale is associated with re-entry pathways in the cardiac conduction system.

If one pathway, such as the Purkinje fibers, is obstructed and an alternative pathway experiences slower conduction, this can trigger an ectopic beat to arise on the downstream side of the blockage.

Additionally, PVCs can be attributed to after-depolarizations that occur on a molecular level. These changes create conditions conducive to spontaneous depolarization of ventricular myocytes. Factors contributing to this include hypomagnesemia, hypokalemia, excess calcium, and excessive catecholamines.

Etiology

Advanced age

Bundle branch block

African American

Male gender

Hypomagnesemia

Hypertension

Hypokalemia

Underlying ischemic heart disease

Genetics

Prognostic Factors

Clinical History

The most prevalent sensation associated with premature ventricular contractions is the perception of a skipped heartbeat followed by a fluttering sensation. Patients frequently report experiencing heart palpitations. However, it is important to note that most patients do not exhibit any accompanying symptoms alongside these palpitations.

Nevertheless, some individuals may encounter additional sensations such as lightheadedness, chest discomfort, chest pain, shortness of breath, and anxiety. In rare cases, syncope may result from PVCs. When conducting a comprehensive patient assessment, it is essential to gather a detailed history.

This should encompass any associated symptoms related to the palpitations, the patient’s medical history, their current medications and supplement usage, and a thorough exploration of their social history. Furthermore, it is crucial to inquire about the potential use of illicit drugs, especially in patients who frequently experience PVCs, as this information can be vital in determining the underlying causes or triggers of the arrhythmia.

Physical Examination

During a physical examination, if a patient is experiencing premature ventricular contractions at the time, auscultation of the heart may reveal an irregular heart rhythm. In certain cases, the presence of cannon A wave may lead to sensations of chest or neck discomfort.

However, aside from these potential findings, there are typically no direct physical examination indicators. It is worth noting that in cases of prolonged run of PVCs, the patient may exhibit symptoms of low blood pressure.

Therefore, it is imperative to assess the patient’s vital signs and conduct a comprehensive examination of their cardiovascular system. In situations where the patient complains of dizziness, it is essential to explore other potential underlying causes, and performing an orthostatic examination to assess the patient’s response to changes in posture can be beneficial in the diagnostic process.

Age group

Associated comorbidity

Associated activity

Acuity of presentation

Differential Diagnoses

Bigeminy

Atrial fibrillation

Trigeminy

Quadrigeminy

Supraventricular tachycardia

Sinus arrhythmia

Sustained ventricular tachycardia

Laboratory Studies

Imaging Studies

Procedures

Histologic Findings

Staging

Treatment Paradigm

The treatment paradigm for premature ventricular contractions involves a tailored approach based on the frequency and symptoms of PVCs. Asymptomatic and infrequent PVCs often require no treatment or may be managed by minimizing stimulant intake, correcting electrolyte imbalances, and reducing stress. Symptomatic or frequent PVCs may be addressed with medications such as antiarrhythmics, beta-blockers, or calcium channel blockers.

In severe cases where pharmacological treatment is ineffective, radiofrequency catheter ablation may be considered, particularly for patients with very frequent or refractory PVCs, aiming to eliminate the source of abnormal electrical signals and potentially reverse PVC-induced cardiomyopathy. The treatment strategy should be individualized to each patient’s specific clinical presentation and needs.

by Stage

by Modality

Chemotherapy

Radiation Therapy

Surgical Interventions

Hormone Therapy

Immunotherapy

Hyperthermia

Photodynamic Therapy

Stem Cell Transplant

Targeted Therapy

Palliative Care

intervention-with-a-procedure

For some patients with an exceptionally high frequency or those with symptomatic PVCs that do not respond to pharmacological treatment, radiofrequency catheter ablation may be considered.

This specialized procedure is performed by an electrophysiologist, who targets and eliminates the specific area of heart tissue responsible for the ectopic beats. Successful ablation has been shown to reverse PVC-induced cardiomyopathy, providing significant clinical benefits. 

phase-of-management

• Asymptomatic Management 

Patients who encounter asymptomatic premature ventricular contractions typically do not necessitate treatment. In an emergency room setting, the approach for patients with hypoxia involves administering oxygen, addressing any electrolyte imbalances, and evaluating for potential drug toxicity.

Simultaneously, it is crucial to rule out the presence of an acute myocardial infarction. It’s essential to emphasize that the routine use of medications like lidocaine and other antiarrhythmic drugs is not advisable when dealing with acute MI.  

• Symptomatic Management 

In many instances, PVCs may be triggered by excessive consumption of stimulants or imbalances in potassium and magnesium levels. Managing these patients is often straightforward and involves reducing stimulant intake and restoring electrolyte balance.

These management strategies can also be applicable to individuals with asymptomatic and infrequent PVCs who still find them bothersome. Additionally, stress reduction can be beneficial for both groups of patients. 

Medications from various classes are employed in the treatment of frequent and symptomatic PVCs, including antiarrhythmics, calcium channel blockers, and beta-blockers. Commonly prescribed antiarrhythmics include amiodarone and flecainide. 

Medication

Future Trends

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References