1. Supraventricular Tachycardia: Mechanisms, Diagnosis, & Management
ECG Interpretation
Supraventricular Tachycardia: Mechanisms, Diagnosis, & Management
William A. Shapiro, M.D.
advancing health worldwide TM
Department of Anesthesia and Perioperative Care

2. Normal Sinus Rhythm
Normal sinus rhythm results from the initiation of an electrical signal (the cardiac impulse) by cells of the sinus node at a rate appropriate to the age and state of activity of the individual, and then the propagation of that signal in an orderly manner through the atria, A-V junction, ventricular specialized conducting system and the ventricular myocardium
There’s no number here

3. Cardiac Conduction System
Bachmann’s bundle
Sinus node
Internodal pathways
Left bundle branch
AV node
Bundle of His
Posterior division
Anterior division
Purkinje fibers
Right bundle branch

4. Arrhythmia
An arrhythmia reflects either abnormally rapid or slow impulse initiation by the sinus node, or interruption of the sinus rhythm by impulses originating from some other site in the heart, either for short or long periods of time
Define abnormal in terms of what deviates from the expected.

5. Mechanisms of Arrhythmias
Reentry
Automaticity
Altered normal automaticity
Abnormal automaticity
Triggered Rhythms due to DAD (delayed after depolarizations
At the bedside, watching a patient die is not the time to ponder the latest theories in the mechanisms of arrhythmia. This is the time to do the best you can do to restore cardiac rhythm and save a life.

6. Causes of Arrhythmias Physiologic and Pathologic Processes
Vagal stimulation, Fever, Hypothermia
Electrolyte abnormalities, CNS problems
Hypovolemia, Pain, anaphylaxis, etc.
Preexisting Cardiac & Pulmonary Disease
Acute coronary syndrome, HTN, AODM
COPD, hypoxia, hypercarbia
These are the things to think about. What’s going on with this patient, at this time, right now.

7. Supraventricular Tachycardia
Definition
All forms of tachycardia (rate > 100 bpm) that arise above the bifurcation of the His bundle. Paroxysmal = sudden onset.
Require AVN or atrial tissue, or both, for initiation and maintenance of the arrhythmia.
Typically (P)SVT has a narrow QRS complex, but the QRS complex may be wide at baseline, or become wide due to rate dependent BBB.
Most reviews exclude A-fib & A-flutter, and MAT.

8. Supraventricular Tachycardia
Incidence/Prevalence
Prevalence is distinct from incidence.
Prevalence is a measurement of all individuals affected by the disease within a particular period of time, whereas;
Incidence is a measurement of the number of new individuals who contract a disease during a particular period of time.
Reference:

9. Supraventricular Tachycardia
Incidence/Prevalence
Incidence (new cases): 35 cases per 100,000 persons per year.
Prevalence (all affected): 2.25 per 1000 (excluding atrial fibrillation, atrial flutter, and multifocal atrial tachycardia).
Increases with age and the presence of CV disease.
Not usually associated with structural heart disease.
Delacrétaz E. Supraventricular Tachycardia. N Engl J Med. 2006

10. Supraventricular Tachycardia
Symptoms
Palpitations: A trigger is usually not identified.
Feeling of heart pounding in the chest and neck.
Anxiety, light-headedness, dyspnea.
Syncope and chest pain are uncommon, but may indicate CAD, especially in older patients.
Psychological stress is very common.

11. Supraventricular Tachycardia
Mechanisms
Reentry- approx 90% of all SVT. Either reentry within the AVN (60%) or using an accessory bypass tract (30%). Almost all reentrant SVTs are started with a PAC.
Atrial focus- approx 10%. Automaticity or Triggered activity
Important concepts- conduction time and refractory period.
Fast conduction typically has a long refractory period.
Slow conduction typically has a sort refractory period.

12. Supraventricular Tachycardia
Onset of SVT

13. Supraventricular Tachycardia
Mechanisms
Ferguson JD. Contemporary Management of Supraventricular Tachycardia. Circulation. 2003

14. Supraventricular Tachycardia
Is this Sinus Rhythm or SVT?
What’s missing?

15. Supraventricular Tachycardia
What’s happening here?

16. Supraventricular Tachycardia
Classification
AV Node Dependent- Reentry- approx 90% of all SVT. Either reentry within the AVN (60%) or using an accessory bypass tract (30%).
AV Node Independent- Atrial focus- approx 10%. Automaticity or Triggered activity.
Thinking of SVT in this way can help with treatment.

17. Treatment of All Cardiac Arrhythmias
All arrhythmias that are hemodynamically significant require immediate cardioversion, defibrillation, or cardiac pacing

18. Supraventricular Tachycardia
Treatment
AV Node Dependent- Vagotonic maneuvers- CSM, facial emersion in water, coughing, straining, etc. Drugs- Adenosine: 6 or 12 mg., verapamil: 5 mg up to 15 mg Diltiazem, beta blockers may also be used on the AVN. Ibutilide, procainamide, and flecainide, affect the bypass tract
AV Node Independent- Heart rate control is the goal. Beta Blockers- sotalol.
Catheter ablation considered a long term option.

19. Supraventricular Tachycardia
Not Discussed
Atrial Fibrillation
Atrial Flutter
Multifocal Atrial Tachycardia
Sinus Node Arrhythmias

20. Supraventricular Tachycardia
References
Fox DJ, et al. Supraventricular Tachycardia: Diagnosis and Management. Mayo Clin Proc. 2008;83(12):
Delacrétaz E. Supraventricular Tachycardia. N Engl J Med. 2006;354:
ACC/AHA/ESC guide-lines for the management of patients with supra- ventricular arrhythmias. J Am Coll Cardiol Oct 15;42(8):
Ferguson JD, et al. Contemporary Management of Paroxysmal Supraventricular Tachycardia. Circulation 2003;107:
Salerno JC, et al. Supraventricular Tachycardia. Arch Pediatr Adolesc Med ;163(3):