OzEMedicine - Wiki for Australian Emergency Medicine Doctors

see also:

• cardiology
• cardiac arrhythmias

• a premature ventricular contraction or ventricular ectopic beat is a cardiac contraction that is generally premature or occurs before the expected sinus QRS complex and arises out of the ventricular tissue.
• when a PVC follows every atrial beat, it is called bigeminy
• when a PVC occurs every 3rd beat, it is called trigeminy
• when 2 PVCs occur in a row, they are called a couplet, when 3 or more occur in a row, then it is called a salvo
• PVCs and bigeminy may be a sign that all is not well with the heart and the patient is at risk of a ventricular fibrillation (VF) when they occur in the setting of acute myocardial ischaemia, hypoxia, prolonged QTc, drug overdoses or metabolic disturbances such as hypokalaemia
  • when the PVCs occur near the peak of the T wave of the preceding beat,these beats predispose the patient to ventricular tachycardia or fibrillation. This R-on-T pattern is often seen in patients with acute myocardial infarction or long Q-T intervals. In the latter case, the triggered arrhythmia would be torsade.
  • couplets, salvos or multifocal PVCs also suggest a higher risk
• on the other hand, in patients with no evidence of the above, PVCs and bigeminy are usually regarded as benign and not treated other than to advise avoidance of stimulants, manage any underlying hypertension, and if symptomatic consider a beta adrenergic blockers
  • recently however, evidence suggests that some patients with frequent ventricular ectopy may be at risk of developing dilated cardiomyopathy and that ablation of the ectopic focus appears to reverse this cardiomyopathy¹⁾

• the QRS complex is wide and often premature with increased amplitude and of a bizarre shape.
• the QRS width is 0.12 second or wider.
• the T wave is of opposite polarity to QRS complex.
• there is no related P wave (unless there is retrograde conduction back through the AV node, which causes the P wave to occur in or after the QRS complex).
• usually the PVC is followed by a fully compensated pause.
• they may be unifocal (all look the same) or multifocal

• the higher the grade the higher the risk of ventricular tachycardia (VT) or ventricular fibrillation (VF)

• search for a treatable underlying cause:
  • check oxygen saturation and ventilation.
  • check electrolytes – K+, Mg++
  • is the patient having an acute myocardial ischaemic event
  • uncontrolled hypertension
  • could there be a drug overdose, in particular, digoxin toxicity or theophylline and methylxanthine poisonings and overdoses
• Ensure appropriate or accessible intravenous cannula or drug line.
• In general, the treatment is to treat the cause and anti-arrhythmic agents should be avoided although in the setting of acute coronary syndrome or if they become symptomatic, beta adrenergic blockers may be considered if haemodynamically stable.
• lignocaine has fallen out of favour but may be considered if either:
  • symptomatic, complex ectopy in a patient having an MI
  • symptomatic ectopy in patient with prolonged QTc as most other agents such as amiodarone tend to further lengthen the QTc.
• amiodarone may be considered if ectopy is high risk and the patient is haemodynamically compromised and there is normal QTc.
• patients with low grade ectopy (including bigeminy) with no underlying cardiac, drug or metabolic cause on non-invasive investigations can usually be managed with reassurance ²⁾ and outpatient follow up by local doctor or perhaps cardiology if it is persistent and frequent as catheter ablation therapy may be indicated in some patients.
• in patients with chronic underlying cardiac disease, left ventricular dysfunction has a stronger association with increased mortality rate than do PVCs. Many now believe that PVCs reflect the severity of heart disease rather than contribute to arrhythmogenesis ³⁾

• Electrolyte imbalances: Changes in electrolyte levels, which can occur during and after pregnancy, may lead to arrhythmias.
• Hormonal changes: The post-partum period involves significant hormonal shifts that can affect the cardiovascular system.
• Increased cardiac output: Pregnancy and the post-partum period place increased demands on the heart, which can lead to arrhythmias in some women.
• Stress and sleep deprivation: The post-partum period can be stressful and may involve significant sleep deprivation, both of which can contribute to the development of arrhythmias.
• Underlying heart disease: Pre-existing or undiagnosed heart conditions, such as cardiomyopathy or ischemic heart disease, can manifest as arrhythmias post-partum.
• Medications: Certain medications used during or after delivery may have arrhythmogenic effects.
• Spontaneous Coronary Artery Dissection (SCAD): SCAD is a common and under-recognized cause of myocardial infarction during the post-partum period, which can lead to ventricular bigeminy due to the resulting ischemia.
• Coronary Vasospasm: Methylergonovine, a medication used to control bleeding after childbirth, can induce coronary vasospasm, which may lead to myocardial ischemia and subsequent ventricular bigeminy.
• Peripartum Cardiomyopathy (PPCM): PPCM is a form of heart failure that occurs during the last month of pregnancy or within five months after delivery. It can lead to left ventricular dysfunction and arrhythmias, including ventricular bigeminy.
• Pre-eclampsia and Hypertension: Pre-eclampsia and hypertension can cause chronic kidney disease and left ventricular hypertrophy, which may predispose to ventricular arrhythmias.
• Left Ventricular Noncompaction (LVNC): LVNC can be associated with ventricular arrhythmias, including bigeminy, and may be acquired during post-partum life.