SVT

Symptoms

Supraventricular tachycardia may come and go suddenly, with stretches of normal heart rates in between. Symptoms may last anywhere from a few minutes to a few days, and some people have no symptoms at all.

• Shortness of breath
• Lightheadedness or dizziness
• Sweating
• Palpitations
• Syncope

Causes

• Heart failure
• Thyroid disease
• Heart disease
• Chronic lung disease
• Smoking
• Drinking too much alcohol
• Consuming too much caffeine
• Drug use, such as cocaine and methamphetamines
• Certain medications, including asthma medications and over-the-counter cold and allergy drugs
• Surgery
• Pregnancy
• Wolff-Parkinson-White syndrome

Risk factors

• Age. Some types of supraventricular tachycardia are more common in people who are middle-aged or older.
• Coronary artery disease,  previous heart surgery. myocardial infarction, Valvular heart disease, prior heart surgery, heart failure, cardiomyopathy.
• Congenital heart disease.
• Thyroid problems. Having an overactive or underactive thyroid gland can increase your risk of supraventricular tachycardia.
• Drugs and supplements. Certain over-the-counter cough and cold medicines and certain prescription drugs may contribute to an episode of supraventricular tachycardia.
• Anxiety or emotional stress
• Physical fatigue
• Diabetes. Your risk of developing coronary artery disease and high blood pressure greatly increases with uncontrolled diabetes.
• Obstructive sleep apnea. This disorder, in which your breathing is interrupted during sleep, can increase your risk of supraventricular tachycardia.
• Nicotine and illegal drug use. Nicotine and illegal drugs, such as amphetamines and cocaine, may profoundly affect the heart and trigger an episode of supraventricular tachycardia.

Diagnosis

• Electrocardiogram (ECG)
• Holter monitor
• Echocardiogram.
• Bloods (FBE, U & E, TSH, Glucose, Magnesium, Lipid profile)

Treatment

• Carotid sinus massage.
• Vagal manoeuvres.
• Cardioversion.
• Medications.- adenosine can be used to revert SVT. Administer adenosine as a bolus through a large proximal vein, with oxygen. The initial dose is 6 mg; this can be followed by 12 mg if the initial dose is unsuccessful. Adenosine causes a high grade, temporary AV block, and patients should be warned that they will experience an unpleasant sensation. Patients previously treated with adenosine may refuse it again. A small dose of midazolam (1.5 mg IV) may reduce the recall of unpleasant symptoms without adverse outcomes. There is evidence to suggest verapamil and adenosine have similar clinical outcomes.11 However, misinterpretation of the ECG is common and verapamil is contraindicated in broad complex arrhythmias. Therefore, adenosine may be safer.

• Catheter ablation.