Sinus Tachycardia

Exam Cram

• Sinus Tachycardia is the commonest cause of tachycardia

• Diagnosis: ECG- HR > 100, QRS < 120, regular, p waves present

• Broad range of causes from recent exercise, pain, anxiety, dehydration; infection, inflammatory response

• Management: DC shock if unstable, otherwise as per underlying cause

Outline

Assessment

History

• Recent movement/ exercise, pain, dehydration, 

• Infection, inflammatory condition, trauma, 

Examination

• Fluid status

• Infective screen

Investigations

• FBC, EUC, LFT with TFTs, calcium/ magnesium/ phosphate

• Septic screen- blood/ urine cultures; CXR, viral PCR; CRP/ PCT

• Weight

Diagnosis

Diagnostic criteria: ECG: (3/3)

• Heart rate > 100 bpm

• QRS < 120ms

• P waves present, regular QRS

Classification (aetiology):

• Exercise, pain, anxiety, dehydration

• Infection

• Cardiac: myocardial infarction, decompensated heart failure, pulmonary embolus, 

• Inflammatory conditions

• Endocrine: hyperthyroidism

Management

Acute 

1. Unstable

   • DC Cardioversion

   • Peri-arrest pager, senior support, HDU/ resus

2. Stable: 

   • Symptom control: analgesia, address concerns

   • Fluid status

     • Dehydration: fluids 

     • Overloaded: furosemide

   • Replace electrolytes

     • K+> 4.0

     • Mg > 1.0

   • Treat underlying cause

Med Reg Notes

Betablockers

There can be a temptation to give beta blockers. However there are commonly adverse effects from patients with an appropriate tachycardia of unknown cause given betablockers and then crash, therefore sinus tachycardia is treated by managing the underlying cause. 

Resources and References

Written in 2024