Inappropriate sinus tachycardia: Difference between revisions
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==Pathophysiology== | ==Pathophysiology== | ||
==Epidemiology and Demographics== | ==Epidemiology and Demographics== | ||
Revision as of 12:24, 10 September 2012
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Inappropriate sinus tachycardia Microchapters |
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Differentiating Inappropriate Sinus Tachycardia from other Medical Conditions |
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Diagnosis |
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Treatment |
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Case Studies |
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Inappropriate sinus tachycardia On the Web |
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American Roentgen Ray Society Images of Inappropriate sinus tachycardia |
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Directions to Hospitals Treating Inappropriate sinus tachycardia |
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Risk calculators and risk factors for Inappropriate sinus tachycardia |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Synonyms and keywords: IST; chronic nonparoxysmal sinus tachycardia
Overview
Historical Perspective
Pathophysiology
Epidemiology and Demographics
The disorder is uncommon.
Sex
More common in women.
Age
Most patients are in their late 20s to early 30s.
Differentiating Inappropriate Sinus Tachycardia from other Medical Conditions
The following medical conditions must be excluded as a cause of tachycardia:
Differentiating Inappropriate Sinus Tachycardia from other Supraventricular Arrhythmias
Diagnosis
Diagnostic Criteria
No formal diagnostic criteria exist. A diagnosis of Inappropriate sinus tachycardia is primarily a diagnosis of exclusion and the following must be observed:
- Exclusion of all other causes of sinus tachycardia
- Common forms of supraventricular tachycardia (SVT) must be excluded
- Normal P wave morphology
- A resting sinus tachycardia is usually (but not always) present
- A nocturnal reduction in heart rate from over 100 beats per minute to 80 - 90 beats per minute
- There is an inappropriate heart rate response on exertion so that the heart rate accelerates to 140 - 150 beats per minute with minimal exertion.
- The mean heart rate during 24 hrs of monitoring is > 95 bpm
- Symptoms are documented to be due to tachycardia
- Hypotension may occasionally be observed
- Syncope (fainting) is occasionally reported
Symptoms
Symptoms reported by patients vary in frequency and severity. Symptoms associated with Inappropriate sinus tachycardia include:
- Blurred vision
- Frequent palpitations
- Dyspnea (shortness of breath) and palpitations on exertion
- Pre-syncope (feeling as if about to faint)
- Fatigue
- Dizziness
- Exercise intolerance
- Occasional paresthesia and cramping
- Symptoms associated with autonomic nervous system disturbance, including GI disturbance
- Orthostatic hypotension with a drop in blood pressure on standing
Treatment
Treatments in the form of pharmacological therapy or catheter ablation are available, although it is currently difficult to treat successfully.
Beta-blockers
In so far as the pathophysiology of IST involves abnormal sensitivity to adrenaline, betaa-blockers can be helpful.
Calcium Channel Blockers
Although calcium channel blockers slow conduction through the AV node, they have been marginally effective in the treatment of IST.
Ivabradine
A new selective sinus node inhibitor Ivabradine is also being used to treat IST.
Treatments Related to Dysautonomia and POTS
In so far as the underlying pathophysiology may involve a dysautonomia and features of Postural orthostatic tachycardia syndrome (POTS), some therapies more commonly used to treat these disorders have been tried:
Fludrocortisone (Florinef)
POTS and dysautonomia have been associated with decreases in blood volume, and this drug promotes sodium retention.
Midodrine
Midodrine increases vasoconstriction, and prevents falls in blood pressure.
Serotonin-reuptake inhibitors (SSRIs)
SSRIs have proven effective in treating some patients with dysautonomia.
Catheter Ablation
Invasive treatments include forms of Catheter ablation has gained favor among electrophysiologists in the treatment of IST.
Sinus Node Modification
This procedure involves selective ablation of the sinus node. The rhythm reoccurs in 80% of cases.
Complete Sinus Node Ablation
This procedure requires implantation of a Permanent Artificial pacemaker)
AV Node Ablation
In cases resistant to sinus node ablation, AV node ablation with creation of an iatrogenic complete heart block, may be neccessary. This procedure requires implantation of a permanent artificial pacemaker.
See also
- Supraventricular tachycardia
- Sinus tachycardia
- Postural orthostatic tachycardia syndrome
- Dysautonomia
References