Sinus Tachycardia Syndromes

If someone has a sinus tachycardia this means that their pulse rate is over 100 beats per minute (and the heartbeat comes from the normal place in the heart). This is normal in healthy people if, for example they are exercising. This can also happen if someone is poorly with, for example, an infection or fever.

Occasionally people can have a sinus tachycardia when they are resting (lying down, sitting or standing) with no obvious illness. These people can develop symptoms of palpitations, breathlessness, fatigue, dizziness and, occasionally, blackouts. When this happens they may have a sinus tachycardia syndrome such as inappropriate sinus tachycardia syndrome (ISTS) or postural orthostatic tachycardia syndrome (POTS).

ISTS and POTS are part of a group of conditions that come under the umbrella term “Cardiovascular autonomic disorders” and whilst they are not known to be life threatening they can cause debilitating symptoms and great emotional distress.

Sinus Tachycardia Syndromes

If someone has a sinus tachycardia this means that their pulse rate is over 100 beats per minute (and the heartbeat comes from the normal place in the heart). This is normal in healthy people if, for example they are exercising. This can also happen if someone is poorly with, for example, an infection or fever.

Occasionally people can have a sinus tachycardia when they are resting (lying down, sitting or standing) with no obvious illness. These people can develop symptoms of palpitations, breathlessness, fatigue, dizziness and, occasionally, blackouts. When this happens they may have a sinus tachycardia syndrome such as inappropriate sinus tachycardia syndrome (ISTS) or postural orthostatic tachycardia syndrome (POTS).

ISTS and POTS are part of a group of conditions that come under the umbrella term “Cardiovascular autonomic disorders” and whilst they are not known to be life threatening they can cause debilitating symptoms and great emotional distress.

Inappropriate Sinus Tachycardia Syndrome

What is it?

Inappropriate Sinus Tachycardia (IST) is a condition in which an individual’s resting heart rate is abnormally high – greater than 100 beats per minute or rapidly accelerating to over 100 beats per minute without an identifiable cause.

How is it diagnosed?

  • ECG for resting heart rate: for IST a resting heart rate generally must exceed 100bpm
  • 24hr ECG/ Holter monitor: for IST the average heart rate during 24 hrs is usually >90bpm
  • Exercise test: for IST there is an inappropriate heart rate response to exercise
  • Other known causes of sinus tachycardia must be excluded (e.g. infection, anaemia)What is it?How is it diagnosed?
  • Postural Orthostatic Tachycardia Syndrome (POTS) is a condition in which (1) There are frequent symptoms that occur with changing posture (usually lying/sitting to standing); (2) an increase in heart rate of more than 30 beats per minute (bpm) when moving from a recumbent to a standing position (or > 40 bpm in individuals 12 to 19 years of age); and (3) the absence of orthostatic hypotension (> 20 mm Hg drop in systolic blood pressure).
  • Postural Orthostatic Tachycardia Syndrome
  • ECG/heart monitor for heart rate when lying down and standing up
  • Tilt test
  • 24hr ECG can be useful to look at heart rate during a normal day
  • Other known causes of sinus tachycardia must be excluded (e.g. infection, anaemia)
  • Other conditions that are associated with POTS need to be looked for (e.g. hypermobility)

Helpful Resources

Please contact Dr Belham who specialises in Sinus Tachycardiac Syndromes at the Cambridge Heart Clinic. He provides outpatient clinics every Monday between 4-7pm.