Hi friend,
Welcome to Health Care Magic

Racing of heart beats needs to be documented by ElectroCardioGram (ECG / EKG).
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THE FIRST STEP IS TO SEE A CARDIOLOGIST
THE POSSIBLE DIAGNOSIS IS SVT (SUPRA VENTRICULAR TACHYCARDIA)
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Anxiety / Alcohol / Tobacco / Caffeine (too much coffee, cola) are common causes.
Medicines may be responsible – like phenlephrine, pseudoephedrine used for ‘cold’ / salbutamol, salmeterol used for asthma / Illicit ‘drugs’ like amphetamine are notorious to cause abnormal beats
In young age like your daughter, it could be from abnormal nerve paths (pass tracts) in the heart.
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It is advisable to investigate.
     A thorough history and physical examination is the first step -
     Routine 12-lead Electrocardiogram (ECG) is part of clinical examination.
     If a routine ECG does not show, 24 to 48 hour AMBULATORY MONITORING (Holter) is done to analyse and plan for further management
     ECHOcardiogram is necessary to see the heart valves (Mitral Valve Prolapse) / heart muscle (Cardiomyopathy) and heart function (Ejection fraction, wall motion abnormality).
     LABORATORY work-up is routine - like blood counts, sugar, urea, electrolytes (potassium in particular), thyroid (over-active) etc. The treating doctor will suggest based on the situation.

     There are advanced techniques of investigations of increasing complexity (some of them invasive), depending on need. The treating doctor may suggest them based on the situation. If there are no clues and if one is still bothered by it to the extent of interfering with life style - there are tests like Electro Physiological Studies (EPS) – it resembles angio > a catheter is put inside the heart, electrical activity recorded, stimulation and suppression tests are carried out, suitable medicine tested and so on. The test is invasive, and is not generally done unless there are compelling indications. The specialist is called ELECTROPHYSIOLOGIST.
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     The first line medicine is generally beta blockers – Metoprolol; slow release and small dose – will benefit. Your doctor will give proper prescription and follow up
     If they are not effective and if the problem is severe, several other classes of drugs are available – - acting by different mechanisms - the specialist will decide tailored to the individual / they may have side effects and need frequent follow up.

There are other advanced treatment modalities - like RF ABLATION by Electro-physiologist, which can often ensure permanent cure / often without need for medications.
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Relax. She is young; you sound intelligent. She stands an excellent chance of returning to normalcy.
She is tolerating the rate well - means that she may not have any basic disease of the valve, muscle and so on of her heart. Be in touch with your doctor - it is a question of time and she will be well. Medicine is well advanced nowadays – management is possible for almost all situations...

Take care
Wishing speedy recovery
God bless
Good luck

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