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Diagnostic Topic – Supraventricular Tachycardia (SVT)
1. What Is the Diagnosis?
The EKG demonstrates supraventricular tachycardia (SVT). SVT is characterized by a regular, rapid rhythm originating above the ventricles, with a narrow QRS complex (<120 ms). on the strip, rate is fast and qrs complexes are uniform narrow, p-waves usually absent or hidden within preceding t-wave. there no visible flutter waves fibrillatory waves, helping distinguish svt from atrial fibrillation. this combination of a fast, regular tachycardia with narrow classic for svt.
2. What Case Will Go Along With This EKG?
The typical clinical scenario is a patient presenting with:
Common triggers or associations include:
3. How Do You Treat SVT?
Initial treatment focuses on slowing the AV node to interrupt the reentry circuit most commonly responsible for SVT.
Step-by-step treatment:
1. Vagal maneuvers
(first-line)
These increase vagal tone and may terminate the rhythm.
2. Intravenous adenosine
(drug of choice)
If vagal maneuvers fail, adenosine is given as a rapid IV push. It transiently blocks AV nodal conduction and can stop the arrhythmia immediately. It is the most effective acute therapy.
3. If adenosine does not work
Use medications that slow AV nodal conduction:
4. If the patient is unstable
If there is hypotension, altered mental status, or signs of shock, immediate synchronized cardioversion is required.
1. What Is the Diagnosis?
The EKG demonstrates supraventricular tachycardia (SVT). SVT is characterized by a regular, rapid rhythm originating above the ventricles, with a narrow QRS complex (<120 ms). on the strip, rate is fast and qrs complexes are uniform narrow, p-waves usually absent or hidden within preceding t-wave. there no visible flutter waves fibrillatory waves, helping distinguish svt from atrial fibrillation. this combination of a fast, regular tachycardia with narrow classic for svt.
2. What Case Will Go Along With This EKG?
The typical clinical scenario is a patient presenting with:
- Sudden-onset rapid palpitations
- Lightheadedness or dizziness
- Possible shortness of breath, anxiety, or diaphoresis
- Symptoms that begin abruptly and may stop abruptly
Common triggers or associations include:
- Caffeine intake (coffee, energy drinks)
- Sympathetic stimulants (decongestants, cocaine, amphetamines)
- Psychological stress or anxiety
- Hyperthyroidism
- History of paroxysmal episodes of rapid heartbeat that resolve spontaneously
3. How Do You Treat SVT?
Initial treatment focuses on slowing the AV node to interrupt the reentry circuit most commonly responsible for SVT.
Step-by-step treatment:
1. Vagal maneuvers
(first-line)
- Carotid sinus massage (unilateral, gentle, after checking for carotid bruit)
- Valsalva maneuver
- Cold water immersion or face-in-ice-water technique
These increase vagal tone and may terminate the rhythm.
2. Intravenous adenosine
(drug of choice)
If vagal maneuvers fail, adenosine is given as a rapid IV push. It transiently blocks AV nodal conduction and can stop the arrhythmia immediately. It is the most effective acute therapy.
3. If adenosine does not work
Use medications that slow AV nodal conduction:
- Calcium channel blockers such as verapamil or diltiazem
- Beta blockers
- Digoxin (less commonly used today but historically included in exam materials)
4. If the patient is unstable
If there is hypotension, altered mental status, or signs of shock, immediate synchronized cardioversion is required.
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