A faster-than-normal heart rate comes from:

• excitation impulses of the heart contractions produced in the physiological pacemaker (sinus node)
  • sinus tachycardia (normal response during exertion, emotion, fever, anxiety, anaemia, dehydration, hypotension, inflammation, pulmonary embolism, heart failure, pheochromocytoma, taking CNS stimulating drugs)
• cardiac excitation impulses generated from other (than the sinus node) sites in the heart - tachyarrhythmias
  • supraventricular tachyarrhythmias (rhythm disturbances involving the atria of the heart, originating from ectopic foci of pathological atrial muscle cells)
    • atrial fibrillation,
    • atrial flutter
    • recurrent nodal tachycardia,
  • ventricular tachyarrhythmias (rapid and chaotic contractions do not allow the ventricles to fill properly with blood between contractions, resulting in reduced cardiac output, leading to complete cardiac arrest) - arrhythmias involving the ventricles, originating from ectopic foci of pathological ventricular muscle cells
    • ventricular tachycardia,
      • ventricular fibrillation.