Tachycardias (>120 bpm)

CLINICAL DIAGNOSTIC MANUAL

Tachycardia, defined as a heart rate over 120 beats per minute, can be caused by fever, acute haemorrhage, hypoxia, thyrotoxicosis, severe anaemia, heart failure, pulmonary embolism, medications, or severe electrolyte imbalances. Symptoms often include shortness of breath, pallor, and weakness. Diagnostic tests include blood tests, echocardiogram, arterial blood gases, and imaging studies depending on the underlying cause.

Cause	Symptoms and Signs	Diagnostic Tests
Fever	Elevated body temperature, tachycardia	Temperature measurement, blood tests to identify the cause of fever
Acute Haemorrhage	Sudden blood loss, tachycardia, pallor	Blood tests, imaging studies
Hypoxia	Shortness of breath, cyanosis, tachycardia	Arterial blood gas analysis, pulse oximetry
Thyrotoxicosis	Weight loss, nervousness, tachycardia	Thyroid hormone levels, TSH receptor antibodies
Severe Anaemia	Fatigue, pallor, weakness, tachycardia	Complete blood count, ferritin, iron levels
Heart Failure	Shortness of breath, oedema, tachycardia	Echocardiogram, natriuretic peptides, electrocardiogram (ECG)
Pulmonary Embolism	Chest pain, shortness of breath, tachycardia	Pulmonary angiography, chest computed tomography (CT)
Medications and Drugs	Varies depending on the substance, possible tachycardia	Medical history, blood tests
Severe Electrolyte Imbalances	Dizziness, confusion, muscle weakness, tachycardia	Blood electrolytes, ECG