Paroxysmal tachycardia

Form of tachycardia which begins and ends in an acute (or paroxysmal) manner

Paroxysmal tachycardia
Synonyms	Paroxysmal supraventricular tachycardia, PSVT, paroxysmal SVT, episodic tachycardia
Pronunciation	par-ok-SIZ-mal tak-ee-KAR-dee-uh
Specialty	Cardiology, electrophysiology
Symptoms	Sudden episodes of rapid heart rate, palpitations, chest discomfort, shortness of breath, dizziness, lightheadedness, anxiety, sweating, fatigue, or fainting
Complications	Usually benign in structurally normal hearts, but prolonged or frequent episodes may cause hypotension, syncope, worsening heart failure, angina, rarely tachycardia-induced cardiomyopathy, or hemodynamic instability
Usual onset	Sudden onset; may occur at any age, including children, young adults, and older adults
Duration	Episodes usually start and stop abruptly and may last seconds, minutes, or hours
Types	Atrioventricular nodal reentrant tachycardia (AVNRT), atrioventricular reentrant tachycardia (AVRT), Wolff-Parkinson-White syndrome-associated tachycardia, focal atrial tachycardia, and less commonly other paroxysmal tachyarrhythmias
Causes	Abnormal cardiac electrical circuits, reentry pathways, accessory pathways, enhanced automaticity, or triggered activity arising above the ventricles
Risk factors	Prior episodes of supraventricular tachycardia, accessory pathway such as Wolff-Parkinson-White syndrome, family history of arrhythmia, structural heart disease, myocardial infarction, mitral valve prolapse, rheumatic heart disease, chronic lung disease, pneumonia, pericarditis, hyperthyroidism, stimulant use, excess caffeine, alcohol, stress, and some medications or drug toxicities
Differential diagnosis	Sinus tachycardia, atrial fibrillation, atrial flutter, ventricular tachycardia, wide complex tachycardia, panic attack, hyperthyroidism, pulmonary embolism, anemia, hypoglycemia, stimulant use, and medication-induced tachycardia
Prognosis	Generally good, especially in people without significant structural heart disease. Recurrent symptoms can affect quality of life, but many cases are controllable with lifestyle measures, medication, or curative catheter ablation.
Frequency	Estimated incidence of paroxysmal supraventricular tachycardia is about 2.5 per 1,000 people in the general population

Paroxysmal tachycardia is a form of tachycardia which begins and ends in an acute (or paroxysmal) manner.Here the ectopic pace-maker is located either in atrium, Avn junction or in the ventricle and rapidly discharges impulses varying from 150 to 250 beats per minute. According to the location of the pace-maker the condition is called paroxysmal atrial (PAT), AV junctional or ventricular tachycardia. In atrial and ventricular type the rate varies from 140-240 per minute; but in paroxysmal AV junctional tachycardia it is same as paroxysmal atrial tachycardia i.e. 140-240 per minute. However in non-paroxysmal AV junctional tachycardia the rate is usually less 60-130 per minute. Multifocal atrial tachycardia is called MAT.

It is also known as "Bouveret-Hoffmann syndrome" or Bouveret’s disease. Barbero ito

Cause

The cause of this condition is not accurately known, though it is probably of nervous origin and can be aggravated by physical wear and tear. The symptoms are sometimes very alarming but it is not considered in itself dangerous.PAT occurs in young individuals without any obvious organic heart disease. Supraventricular type may be seen in association with atrial septal defect, Ebstein’s anomaly, mitral valve disease, WPW syndrome, Sick sinus syndrome, Floppy mitral valve syndrome and rarely with ischaemic heart disease. Drugs like Digitalis may also cause it as its toxic effect

It has an increased risk of developing in WPW syndrome and LGL syndrome.

Diagnosis

ECG is helpful for final diagnosis. In atrial tachycardia the QRS complexes are normal but ‘P’ waves will have abnormal morphology. In paroxysmal AV junctional tachycardia the QRS complexes are normal but retrograde ‘P’ waves may be present which are not always visualized. His bundle electrogram or High right atrial electrocardiogram may be helpful. In ventricular type QRS is wide, bizarre and P waves are not clearly seen. A monophasic QS or R wave pattern in precordial leads with no transitional point and sometimes fusion beats or atrial capture beats may be seen. Torsade de pointes is a special form of VT where QRS morphology varies with typical twisting of the points, RR interval is irregular, ventricular rate may be 200-300 beats per minute. Sometimes the rate may be 400 beats per minute. The amplitude of the complexes vary and may be alternately above and below the baseline. This usually occurs in presence of a prolonged QT interval. It may occur spontaneously or after use of drugs which prolong QT duration e.g., Quinidine or in hypokalaemia, hypomagnesemia.PAROXYSMAL TACHYCARDIA.

Symptoms

• 1.Onset is sudden
• 2.Severe palpitation.
• 3.Fluttering sensation in the chest.
• 4.Sometimes dizziness or syncope.
• 5. Precordial pain.
• 6.Breathlessness

Classification

It can be divided by the origin:

• supraventricular tachycardia
• ventricular tachycardia

External links

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