| Paroxysmal supraventricular tachycardia (PSVT) is a disturbance of the normal heart rhythm (arrhythmia), resulting in a spontaneously occurring and sporadic (paroxysmal) rapid heart rate (tachycardia) of more than 100 beats per minute.
Normally, heart chambers (atria and ventricles) contract in a coordinated way. The signal to contract begins in the sinus (sinoatrial, or SA) node. It is conducted through the upper heart chambers (atria) and stimulates them to contract. It passes through the atrioventricular (AV) node and then travels throughout the ventricles (larger, lower chambers) and stimulates them to contract. PSVT occurs from changes in the electrical conduction pathway of the heart. The types of tachycardia that occur depend on where the change in the conduction pathway is initiated. PSVT can begin in the atria, the SA node, or the AV node.
The two types of PSVT are atrioventricular nodal reentry tachycardia (AVNRT) and atrioventricular reciprocating tachycardia (AVRT), also known as accessory pathway tachycardia. The most common type of PSVT is AVNRT. AVNRT occurs when there is an abnormal conduction pathway inside or next to the AV node. AVNRT is usually triggered by a premature atrial impulse. AVRT occurs when the AV node is bypassed completely and a "shortcut" conduction pathway is used, manifesting in a condition called Wolff-Parkinson-White (WPW) syndrome.
An underlying lung or heart disease may cause PSVT. It can occur after a heart attack (myocardial infarction), after lung or heart surgery, or with digitalis toxicity. The abnormal conduction seen in WPW syndrome, however, may be acquired at birth (congenital).Risk: AVNRT is present in women more often than men and usually occurs in middle-aged or older individuals. AVRT is more common in men then women and presents at a younger age, usually adolescence.
Risk factors include lifestyle activities such as smoking, excessive caffeine, and alcohol use. Incidence and Prevalence: Overall PSVT occurs in 1 to 3 individuals per 1,000 people. AVNRT is found in 50% to 60% of individuals with a tachyarrhythmia, and AVRT or WPW occurs in 0.1% to 0.3% of the general population (Ganz). |
Source: Medical Disability Advisor
| History: Individuals with PSVT may complain of a rapid heartbeat (tachycardia); dizziness; lightheadedness; fainting (syncope) or feeling like they may faint (near syncope); neck pounding; shortness of breath; sweatiness (diaphoresis); chest pain; chest tightness; or weakness, fatigue, and nausea. Many individuals with PSVT may complain of anxiety or feeling scared. Physical exam: Symptoms may start and stop suddenly and can last for a few minutes or as long as a day or 2. During an episode, the heart rate will be greater than 100 beats/minute, with rates of 150 to 200 beats/minute with AVNRT and 150 to 250 beats/minute for AVRT; between episodes, the heart rate will be normal (60 to 100 beats/minute). The individual will have a rapid pulse and may appear anxious. There may be signs of poor oxygen perfusion, such as pale skin (pallor), decreased oxygen levels, or confusion. Generally, no other specific physical findings are evident. Tests: Lab testing includes cardiac enzymes to assess for a heart attack in those individuals complaining of chest pain. Additional tests include blood sodium and potassium (serum electrolytes), thyroid hormone levels, a complete blood count (CBC) for anemia and serum digoxin levels for those individuals on digoxin to check for very high or low levels. A chest x-ray may be needed to check for possible fluid in the lungs (pulmonary edema, heart failure). An ultrasound of the heart (echocardiography) may be done to assess for structural heart defects.
An electrocardiogram (ECG) will confirm the diagnosis. Continuous ambulatory monitoring or a 24-hour Holter monitor may be needed to diagnose PSVT because of the sporadic nature of the disorder.
An intracardiac electrophysiology study (EPS) may be required to confirm that the arrhythmia is caused by PSVT. |
Source: Medical Disability Advisor
| Many individuals with PSVT require no treatment because the arrhythmia starts and stops spontaneously and may resolve spontaneously. If symptoms develop or there are underlying cardiac disorders, treatment may be initiated in an attempt to interrupt the arrhythmia and convert back to a normal sinus rhythm. Individuals are advised to avoid nicotine, caffeine, alcohol, fatigue, and stress, all of which are known to provoke tachycardia.
For those with PSVT, however, who experience light-headedness or near fainting (near-syncope), the doctor may initiate measures to interrupt the rapid heart rate (tachycardia) by gently massaging one of the carotid arteries (carotid massage) in the neck and prescribing medications (beta-blockers, calcium channel blockers). Symptomatic individuals may require a procedure to burn the area causing the arrhythmia (radiofrequency catheter ablation, catheter ablation), and those who are severely symptomatic may require immediate electric shock (cardioversion), which is successful in restoring (converting) PVST to a normal heart rhythm in many cases.
Pacemakers designed to interrupt or override the tachycardia may be an alternative to ablation or chronic medications for PVST; however, pacemakers are not normally used for re-entrant or triggered rhythms. Individuals also may learn self-help measures such as coughing, plunging their face in ice water (ice water immersion), or attempting to expel breath while deliberately closing the mouth and nose (Valsalva maneuver). |
Source: Medical Disability Advisor
| PSVT is generally not life-threatening unless other cardiac disorders are present. There is a wide variation in outcome for individuals with PSVT, but most have an excellent outcome, including those who undergo catheter ablation therapy. Success rates for catheter ablation are estimated at between 94% and 100%. |
Source: Medical Disability Advisor
| Complications of PSVT include atrial fibrillation, other arrhythmias, atrioventricular heart block, congestive heart failure, myocardial ischemia and/or infarction, syncope, and sudden death. |
Source: Medical Disability Advisor
| The individual may benefit from a less challenging and stressful job and schedule because stress and fatigue are known triggers for an attack. Until the arrhythmia is successfully treated, those who have jobs that entail the safety of others, such as pilots or bus or cab drivers, should be placed in a different job temporarily. Individuals should not work at jobs with a danger of falling from heights or operating moving or heavy machinery. Once the arrhythmia is controlled, no restrictions or accommodations may be required. |
Source: Medical Disability Advisor
| If an individual fails to recover within the expected maximum duration period, the reader may wish to consider the following questions to better understand the specifics of an individual's medical case. Regarding diagnosis:
- Does individual have a history of lung or heart disease?
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Has individual experienced a recent heart attack (myocardial infarction) or undergone lung or heart surgery?
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Does individual use nicotine, caffeine, and alcohol?
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Does individual take the medication digitalis for heart problems?
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Does individual complain of a rapid heartbeat (tachycardia), dizziness, fainting (syncope), shortness of breath, chest pain or tightness, or weakness?
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Does individual report the sensation of feeling his or her heartbeat (palpitations), light-headedness, feeling "neck-pounding," or feeling ready to faint (near-syncope)?
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Does individual report feeling anxious or scared?
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Was appropriate lab testing done to rule out other abnormalities diagnoses such as thyroid dysfunction, electrolyte imbalances abnormalities, low or high levels of digoxin, or anemia?
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Was an electrocardiogram (ECG) done?
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Was continuous ambulatory monitoring for 24 hours (Holter monitor) required due to the sporadic nature of the disorder?
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Was a diagnosis of PSVT confirmed?
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Was an intracardiac electrophysiologic study done? If so, what were the results?
Regarding treatment:
- Was individual treated with medications? Was the treatment successful?
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Was individual treated with catheter ablation? Were there any complications?
Regarding prognosis:
- Does individual have an underlying cardiac disorder?
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Are there any other underlying disorders that could prolong or prevent recovery?
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Is individual compliant with avoidance of caffeine, alcohol, nicotine, stress, and fatigue?
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Is individual compliant with all medication regimens?
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Have complications of PSVT developed? If so, how will the complication be treated, and what is the expected outcome with treatment?
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Source: Medical Disability Advisor
| Ganz, Leonard, and Monika Ahluwalia. "Paroxysmal Supraventricular Tachycardia." eMedicine. Eds. Alan D. Forker, et al. 27 Oct. 2004. Medscape. 15 Dec. 2004 <http://emedicine.com/med/topic1762.htm>. |
Source: Medical Disability Advisor
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