Paroxysmal Supraventricular Tachycardia
Cardiology (12%) Core Clinical Conditions
1B: Able to identify the condition as a possible diagnosis: may not have the knowledge or resources to confirm the diagnosis or to manage the condition safely, but can take measures to avoid immediate deterioration and refer appropriately
Jump to content
Definition Aetiology Pathophysiology Risk factor Sign and Symptoms Investigations Diagnosis Management
Definition
Paroxysmal supraventricular tachycardia (PSVT) is a rapid heart rate that begins above the ventricles. Paroxysmal refers to periodic occurrence, with episodes occurring either frequently or infrequently (years apart). In PSVT the heart rate is regular, rapid and it can start and stop suddenly.
Aetiology
Patients may develop PSVT due to a variety of medical conditions and medications:
● Hyperthyroidism
● Alcohol
● Chronic lung disease
● Chest wall trauma
● Digoxin toxicity
● Pericarditis
● Hypoxia
● Mitral valve prolapse
● Cardiomyopathy
● Pneumonia
● Myocarditis
● Hypovolemia
● Anxiety
● Salbutamol
● Cocaine
● Myocardial infarction
● Pulmonary embolism
● Verapamil
● Structural heart disease
● Caffeinated beverages
Pathophysiology
There are 3 main causes for a short circuit (an abnormal electrical pathway) in the heart. Each one results in PSVT.
● Atrioventricular Nodal Re-entrant Tachycardia (AVNRT)
This occurs when there is an “extra” signalling pathway in or near the AV node. This extra signal sends electrical impulses rapidly and it causes the sudden fast heart beat.
● Wolff-Parkinson-White Syndrome (WPW)
In this case there are additional muscle fibres connecting the upper (atria) and lower (ventricle) of the heart. This is an accessory electrical pathway causing a loop circuit. This a congenital disorder and if severe the only cure is catheter ablation.
● Atrial Tachycardia
This happens when an electrical impulse in the atria starts in an unexpected place and rapidly repeats, causing tachycardia.
Risk factors
● Women are twice likely to have PSVT
● Pneumonia.
● Current alcohol intoxication.
● Heart diseases
● Asthma medications can trigger PSVT
● Previous myocardial infarction.
● Digoxin toxicity.
● Previous heart surgery.
● Increasing age more likely after age of 65+
● Obesity
● Chronic lung disease (Asthma/COPD)
● high caffeine intake
● Illicit drugs
● Smoking
Sign and symptoms
● Palpitations symptoms
● Light-headedness
● Weakness
● Fatigue
● SOB
● Chest pressure
● Syncope
Investigations
● 12 lead ECG (see image 1)
● 24 hr ECG
● Troponin blood test - if patient present with chest pain symptoms
● Bloods - fbc, u/e, TFT
● Cxr - rule out other causes
● Echocardiogram
Image 1
The ECG demonstrates a regular but narrow complex tachycardia ECG of supraventricular tachycardia (STV).
Diagnosis
Physical examination:
Dizziness
Tachycardia
Management
● If acutely unwell - patient must be admitted to hospital
● Vagal manoeuvres: methods used to activate the vagus nerve and slow down the heart's electrical impulses.
● Medication: adenosine (if vagal manoeuvre fails) or verapamil
● Using electrical impulses for cardioversion while under a general anaesthetic
● Catheter ablation: performed by removing tissue from the heart's conduction pathway to stop abnormal stimulations.
Check out our youtube channel
