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What is Cardiac syncope

Cardiac syncope is due to reduction in the cardiac output
Presyncope / Near syncope –Here the patient feels dizzy, weak and tends to lose postural tone, without loss of consciousness
Reduction of cerebral blood supply for 5 sec - presyncope
Reduction of cerebral blood supply for 10 sec – loss of consciousness
Reduction of cerebral blood supply for 15 sec -seizure.
Causes of cardiac syncope are
1.Electrical abnormalities
  • Extreme bradycardia
  • Heart block
  • Supraventricular or ventricular tachyarrhythmia
2. Mechanical causes
  • Aortic stenosis
  • Hypertrophic obstructive cardiomyopathy
  • Left atrial tumours and thrombus
  • Pulmonary stenosis
  • Pulmonary hypertension
  • Pulmonary embolism
  • Tetralogy of Fallot.
Heart rate < 40 and > 160 will produce hemodynamic symptoms in normal person.