Tachycardias (sinus & ventricular)

Question 1

Tachycardias (sinus & ventricular): Definition

Answer 1

• Sinus tachycardia:
  
  • HR >100bpm
  • an elevated sinus rhythm characterized by an increase in the rate of electrical impulses arising from the SAN
  • I think ST is pretty much just general tachycardia
  • I think, but am not sure, that ST is less serious than VT because the AV node can limit the impact of ST on the ventricles which VT is obv inherantly affecting the ventricles
• ventricular tachycardia
  
  • A type of regular, fast heart rate
  • Although a few seconds may not result in problems, longer periods are dangerous
  • VT can lead to Vfibrillation and then sudden death
  • ie.

ectopic focus in ventricle which depolarises with high frequency: can be life threatening. Diastole not long enough for proper ventricular filling

Question 2

Tachycardias (sinus & ventricular): Aetiology

Answer 2

• Sinus:
  
  • usually a response to physiological stress, such as exercise
  • or an increased sympathetic tone with increased catecholamine release, such as stress, fright, flight, and anger
• Ventricular:
  
  • CAD
  • cardiac scaring
  • aortic stenosis
  • cardiomyopathy
  • electrolyte problems
  • heart attack
  • long Q-T syndrome

Question 3

Tachycardias (sinus & ventricular): Risk factors

Answer 3

Pretty much what you’d expect

• Anemia.
• Diabetes.
• Heart disease.
• Heavy alcohol use.
• Heavy caffeine use.
• High blood pressure.
• Overactive or underactive thyroid.
• Psychological stress or anxiety.

Question 4

Tachycardias (sinus & ventricular): Pathophysiology

Answer 4

I’m just going to repeat the aetiologies here because I’m not sure about the pathophysiology and it’s not clear from research

• Sinus:
  
  • usually a response to physiological stress, such as exercise
  • or an increased sympathetic tone with increased catecholamine release, such as stress, fright, flight, and anger
• Ventricular:
  
  • CAD
  • cardiac scaring
  • aortic stenosis
  • cardiomyopathy
  • electrolyte problems
  • heart attack
  • long Q-T syndrome

Question 5

Tachycardias (sinus & ventricular): Cinical manifestations: key presentations, other symptoms and signs

Answer 5

I think both are relatively asymptomatic except for the expected feeling of the heart beating too fast

• Sinus tachycardia: palpitations, dizziness
• Ventricular tachycardia: often asymptomatic: palpitations, hypotension, syncope, angina, cardiogenic shock

Question 6

Tachycardias (sinus & ventricular): Investigations (diagnosis): 1st line, gold standard & other

Answer 6

• Both require ECG for diagnosis
• Sinus tachycardia:
  
  • regular rhythm, normal P waves, narrow QRS, rate > 100bpm
• Ventricular tachycardia:
  • No visible P waves, wide abnormal QRS, QRS rapid but regular (120-200bpm), T waves can’t be seen

Question 7

Tachycardias (sinus & ventricular): DDx

Answer 7

• I think just other tachycardias/ cardiac arrhythmias

Question 8

Tachycardias (sinus & ventricular): Management

Answer 8

• Sinus tachycardia:
  
  • beta-blockers if symptomatic
  • I think, because ST is pretty much just general tachycardia, it’s not too serious and so the the treatment isn’t too dramatic
• Ventricular tachycardia:
  
  • Hemodynamically unstable with pulse
    
    • cardioversion
  • Hemodynamically unstable without pulse
    
    • defibrillator
  • Hemodynamically stable
    
    • antiarrhythmics (amiodarone)
  • Long-term therapy
    
    • antiarrhythmics or ICD (implantable defibrillator)